Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Processing feature prior to imaging
Reexamination Certificate
2000-06-29
2002-02-19
Chapman, Mark (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Processing feature prior to imaging
C430S300000, C430S302000, C430S306000, C430S394000, C430S494000, C101S467000
Reexamination Certificate
active
06348300
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a process for treating the periphery of an unexposed photosensitive resin plate. More specifically, the present invention relates to a process for removing the stickiness of the periphery of an unexposed photosensitive resin plate.
While the production of printing plates from photosensitive resin plates generally includes steps of exposing, washing out, drying, post-exposing, etc, a step for handling unexposed photosensitive resin plates exists before the exposing step. The said step for handling unexposed plates means taking out unexposed plates from packing cases, cutting them according to the size of negative film, printing images an exposing table, and so on. In the presence of stickiness on the periphery of unexposed plates, the smooth processing of these steps will be prevented, giving rise to inconveniences in handling. The periphery here means the sides of an unexposed plate and is resin surfaces externally bare. For example, the periphery of an unexposed plate sticks to a package or cushion sheet during its removal from a packing case, the periphery of an unexposed plate sticks to a cutting table while the plate is being cut, and the periphery of an unexposed plate sticks to an exposing table or vacuum adhesion sheet during exposing. In addition, problems such as dust deposition on the periphery of unexposed plates, and stickiness of unexposed resin to hands during handling of plates occur, for which reasons a process for removing the stickiness of the periphery of an unexposed plate is desired.
In order to solve these problems, there have been proposed methods including a method in which an inorganic powder is deposited on the periphery of an unexposed plate to remove the surface stickiness, a method in which the periphery of an unexposed plate is covered with a non-adhesive sheet such as release paper, and so on. Of those, the method in which an inorganic powder is deposited on the periphery of an unexposed plate to prevent the stickiness of the surfaces requires a complicated manipulation of the steps for the deposit of the powder, and is of no practical use since it may produce unsatisfactory image quality in the steps of making printing plates, such as exposing, because of the powder deposited on the surfaces of the plate; and the method in which the periphery of an unexposed plate is covered with a non-adhesive sheet such as release paper is of no practical use either, since even if the method could prevent the peripheral resin of the unexposed plate from sticking to the package or cushion sheet, the peripheral resin of the unexposed plate can stick to an exposing table, vacuum adhesion sheet, and to hands during the exposing step.
When the photosensitive resin composition is a photosensitive elastomer containing a conjugated diene polymer, there is practically no appropriate methods in the conventional methods, since the resin of such composition is softer and stronger in stickiness. Accordingly, the present invention aims at developing an easy and effectively practical process for removing the stickiness of the peripheral resin of an unexposed photosensitive resin plate, which causes no problem during making printing plates.
SUMMARY OF THE INVENTION
The present inventors have made intensive studies for the purpose of developing a process for removing the stickiness of the peripheral resin of an unexposed photosensitive resin plate, whereby to improve the present situation, and found that an irradiation of light having a wavelength of 300 nm or below on the peripheral resin of the unexposed plate accomplishes the removal of the stickiness, and completed the present invention. That is, the present invention relates to a process for removing the stickiness of the periphery of an unexposed photosensitive resin plate, which comprises irradiation of light having a wavelength of not more than 300 nm on the periphery of an unexposed photosensitive resin plate until it is free of stickiness.
DETAILED DESCRIPTION OF THE INVENTION
The photosensitive resin plate to be used in the present invention is exemplified by those composed of a polyamide photosensitive resin with, as an essential component, a polyamide which can dissolve or swell in solutions for washing out, such as water, aqueous solutions of alkali, and alcohols, those made of a polyvinyl alcohol photosensitive resin with polyvinyl alcohol as an essential component, those made of a polyester photosensitive resin with, as an essential component, a polyester containing a low molecular unsaturated group, those made of an acrylic photosensitive resin with an-acrylic low molecular polymer as an essential component, and those made of a polyurethane photosensitive resin with polyurethane as an essential component. These photosensitive resins are imparted with photocurability by the addition of photopolymerizable unsaturated monomer, photosensitizer, etc.
Recently, there have been proposed photosensitive flexo plates which allow developing in an aqueous washing solution from the viewpoints of toxicity and safety. Examples thereof include those containing a copolymer of a conjugated diene hydrocarbon and &agr;, &bgr;-ethylenically unsaturated carboxylic acid or its salt as essential components, and a mono-olefin, unsaturated compound, those containing a copolymer of a conjugated diene hydrocarbon polymer or a conjugated diene hydrocarbon, and a mono-olefin unsaturated compound, those containing a photosensitive elastomer composition containing a hydrophilic polymer compound and a non-gaseous ethylenically unsaturated compound, those containing a hydrophobic oligomer containing an &agr;, &bgr;-ethylenically unsaturated group, and those containing an elastomer and a substance which can swell in water. All of these are imparted with photocurability by the addition of photopolymerizable unsaturated monomers, photosensitizers, and so on. While there are many examples of photosensitive resin to be used in the present invention, particularly preferred are those containing a hydrophobic polymer and a hydrophilic polymer which have a strong cohesiveness.
The present invention is preferably applied in particular to a photosensitive resin composition containing a polymer which can be dissolved or swollen in water or an aqueous developer, an ethylenically unsaturated monomer and/or a hydrophobic polymer, and a photoinitiator. For example, such a composition is disclosed in Japanese Unexamined Patent Publication Nos. 211451/1985 and 173055/1985.
Besides the above-mentioned photosensitive resin composition, examples thereof include those containing (A) a hydrophobic polymer having a glass-transition temperature not higher than 5° C. and (B) a hydrophilic polymer, particularly those containing particles having a phase composed mainly of component (A) and a phase composed mainly of component (B) in dispersion; those containing the aforementioned component (A), component (B), (C) an ethylenically unsaturated compound, (D) a solvent in which the solubility (by weight) of component (B) is greater than that of component (A), and (E) a photoinitiator; and those characterized in that particles containing a first phase composed mainly of a hydrophobic polymer which is surrounded by a second phase composed mainly of a hydrophilic polymer are present as a dispersed phase in the photosensitive resin layer. These compositions are particularly preferred in the present invention.
The hydrophobic polymer having a glass-transition temperature not higher than 5° C. as the above-described component (A) includes those which are used as general-purpose elastomers, examples of which are polymers obtained by the polymerization of a conjugated diene hydrocarbon, copolymers obtained by the copolymerization of a conjugated diene hydrocarbon with a mono-olefinically unsaturated compound, and polymers containing no conjugated diene hydrocarbons. As the conjugated diene hydrocarbon, 1,3-butadiene, isoprene, and chloroprene can be used alone or in combination with one another.
As the mono-olefinically u
Ariki Takamitsu
Nampei Masaru
Onodera Kosaku
Yamamoto Katsumasa
Chapman Mark
Leydig , Voit & Mayer, Ltd.
Toyo Boseki Kabushiki Kaisha
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