Abstract: Problem to be Solved To provide a photosensitive resin composition which has good processability even in a relatively low temperature condition near room temperature and exhibits good efficiency in removing debris generated while shaping a printing plate by laser engraving. Solution A photosensitive resin composition, characterized by comprising: (a) 100 parts by mass of a resin having a number average molecular weight of 1,000 or more; and (b) 0.1 to 10 parts by mass of ultrafine particles having a number average particle diameter of primary particles of 5 nm or more and 100 nm or less; wherein the photosensitive resin composition has a viscosity at 20° C. of 50 Pa·s or more and 10,000 Pa·s or less; and a precursor composition, which is obtained by excluding the component (b) from the photosensitive resin composition, has a viscosity at 20° C. of 5 Pa·s or more and 500 Pa·s or less.

Abstract: A photosensitive resin composition for a laser engravable printing substrate, comprising resin (a) having a polymerizable unsaturated group whose number average molecular weight is in the range of 1000 to 20×104, organic compound (b) having a polymerizable unsaturated group whose number average molecular weight is <1000 and organosilicon compound (c) having at least one Si—O bond in each molecule and having no polymerizable unsaturated group in molecules, wherein the content of organosilicon compound (c) is in the range of 0.1 to 10 wt. % based on the whole of photosensitive resin composition.

Abstract: Problem to be Solved To provide a photosensitive resin composition which has good processability even in a relatively low temperature condition near room temperature and exhibits good efficiency in removing debris generated while shaping a printing plate by laser engraving. Solution A photosensitive resin composition, characterized by comprising: (a) 100 parts by mass of a resin having a number average molecular weight of 1,000 or more; and (b) 0.1 to 10 parts by mass of ultrafine particles having a number average particle diameter of primary particles of 5 nm or more and 100 nm or less; wherein the photosensitive resin composition has a viscosity at 20° C. of 50 Pa·s or more and 10,000 Pa·s or less; and a precursor composition, which is obtained by excluding the component (b) from the photosensitive resin composition, has a viscosity at 20° C. of 5 Pa·s or more and 500 Pa·s or less.

Abstract: A process for producing a laser engravable printing substrate, comprising the step of forming a layer of photosensitive resin composition on a cylindrical support or sheeted support and the step of irradiating the formed layer of photosensitive resin composition with light to thereby provide a layer of cured photosensitive resin of 50 ?m to 50 mm thickness, wherein the light for irradiation of the photosensitive resin composition layer contains a ray of 200 to 450 nm wavelength and wherein the light illuminance on the surface of the photosensitive resin composition layer is in the range of 20 mW/cm2 to 2 W/cm2 when measured with the use of UV meter (trade name “UV-M02” manufactured by Ohku Seisakusho) and filter (trade name “UV-35-APR Filter” manufactured by Ohku Seisakusho) and in the range of 3 mW/cm2 to 2 W/cm2 when measured with the use of the above UV meter and filter (trade name “UV-25 Filter” manufactured by Ohku Seisakusho).

Abstract: A cushion for printing or a cushioning layer for printing plate manufactured using a cushioning material for printing having a storage elastic modulus (E?) of 1.0×108 Pa or greater at 20° C. and 1000 Hz enables high-speed printing while keeping a printing quality.

Abstract: A process for producing a cured product of a photosensitive resin, comprising the steps of forming a photosensitive resin composition layer having a thickness of not less than 50 ?m and not more than 50 mm using a photosensitive resin composition containing a hydrogen abstraction-type photopolymerization initiator (d) and an disintegration-type photopolymerization initiator (e), or a photopolymerization initiator (c) having in the same molecule a site, which functions as a hydrogen abstraction-type photopolymerization initiator and a site which functions as an disintegration-type photopolymerization initiator, and irradiating the photosensitive resin composition layer with light in the air to cure the photosensitive resin composition layer.

Abstract: A process for producing a laser engravable printing substrate, comprising the step of forming a layer of photosensitive resin composition on a cylindrical support or sheeted support and the step of irradiating the formed layer of photosensitive resin composition with light to thereby provide a layer of cured photosensitive resin of 50 ?m to 50 mm thickness, wherein the light for irradiation of the photosensitive resin composition layer contains a ray of 200 to 450 nm wavelength and wherein the light illuminance on the surface of the photosensitive resin composition layer is in the range of 20 mW/cm2 to 2 W/cm2 when measured with the use of UV meter (trade name “UV-M02” manufactured by Ohku Seisakusho) and filter (trade name “UV-35-APR Filter” manufactured by Ohku Seisakusho) and in the range of 3 mW/cm2 to 2 W/cm2 when measured with the use of the above UV meter and filter (trade name “UV-25 Filter” manufactured by Ohku Seisakusho).

Abstract: A photosensitive resin composition for a laser engravable printing substrate, comprising resin (a) having a polymerizable unsaturated group whose number average molecular weight is in the range of 1000 to 20×104, organic compound (b) having a polymerizable unsaturated group whose number average molecular weight is <1000 and organosilicon compound (c) having at least one Si—O bond in each molecule and having no polymerizable unsaturated group in molecules, wherein the content of organosilicon compound (c) is in the range of 0.1 to 10 wt. % based on the whole of photosensitive resin composition.

Abstract: Disclosed is a photosensitive resin composition for forming a laser engravable printing element, comprising: (a) 100 parts by weight of a resin which is a plastomer at 20° C., wherein the resin has a number average molecular weight (Mn) of from 1,000 to 100,000 and has a polymerizable unsaturated group in an amount such that the average number of the polymerizable unsaturated group per molecule is at least 0.7, (b) 5 to 200 parts by weight, relative to 100 parts by weight of resin (a), of an organic compound having an Mn of less than 1,000 and having at least one polymerizable unsaturated group per molecule, and (c) 1 to 100 parts by weight, relative to 100 parts by weight of resin (a), of an inorganic porous material. Also disclosed is a laser engravable printing element formed from the above-mentioned resin composition.

Abstract: A heat sensitive type plate material for forming lithography comprising a substrate (1) and, formed thereon, a heat sensitive layer (2), which in turn comprises a hydrophilic polymer (3) having a Lewis base moiety, lipophilic part forming particles (4) which form a lipophilic part on the surface of a plate through the change caused by heat, and polyvalent metal oxide particles (5), the lipophilic part forming particles (4) and the polyvalent metal oxide particles (5) being dispersed homogeneously in the heat sensitive layer (2). The plate material requires no developing process on forming a plate, and can form a lithography which has not only high mechanical strength, but also high printing durability, and further can be prepared with no significant increase of production cost.

Abstract: Disclosed is a photosensitive resin composition for forming a laser engravable printing element, comprising: (a) 100 parts by weight of a resin which is a plastomer at 20° C., wherein the resin has a number average molecular weight (Mn) of from 1,000 to 100,000 and has a polymerizable unsaturated group in an amount such that the average number of the polymerizable unsaturated group per molecule is at least 0.7, (b) 5 to 200 parts by weight, relative to 100 parts by weight of resin (a), of an organic compound having an Mn of less than 1,000 and having at least one polymerizable unsaturated group per molecule, and (c) 1 to 100 parts by weight, relative to 100 parts by weight of resin (a), of an inorganic porous material. Also disclosed is a laser engravable printing element formed from the above-mentioned resin composition.

Abstract: A lithoprinting plate comprising a support and a recording layer which comprises a polyvalent metal ion and a hydrophilic binder polymer having a Lewis base portion containing nitrogen, oxygen or sulfur and which has an oleophilic image area and a hydrophilic non-image area which are printed in a thermal mode, wherein the hydrophilic binder polymer in the hydrophilic non-image area is three-dimensionally cross-linked by the interaction between the polyvalent metal ion and the Lewis base portion.