Dainippon Ink and Chemicals, Incorporated

Kodak Polychrome Graphics, Gmbh

Dianippon Ink and Chemicals, Inc.

Shinji Shimizu

Yasuhiko Kojima

Koji Oe

Yasuyuki Watanabe

Nansei Tasiro

Katsuji Takahashi

Naohito Saito

Maru Aburano

Nansei Tashiro

Shoichi Hotate

Lithographic printing form precursors comprising positive working polymeric coatings on substrates may during storage or transportation undergo undesirable changes in their imaging properties. It has been found that acceptable properties can be restored by carrying out a heat treatment which involves a relatively short heating stage followed by accelerated cooling.

Printing form precursors

In order to provide a computer-to-plate (CTP) plate in which an image can be inscribed by a laser beam having Ithe maximum strength in a near infrared or infrared region, and heat processing is not necessary prior to developing a latent image, and which allows the use of a conventional printing apparatus as it is upon printing, (I) a lithographic printing plate is provided which has on a substrate, a photosensitive layer comprising a photosensitive composition containing a crosslinking agent, an aqueous dispersion of resin fine particles made of a resin which is self water-dispersible having a carboxylic group and a functional group capable of performing cross-linking reactions with the crosslinking agent, and an infrared absorption agent; and (II) an image forming method is provided which is characterized in that after an image has been formed on a photosensitive layer of the lithographic printing plate set forth in the above (I) by using a laser beam, the image is subjected to wet development.

Lithographic printing plate and image forming method

A heat-sensitive composition is disclosed which includes a substance which absorbs light and generates heat, an anionic self water-dispersible resin particle having an acid value of 10 to 300 and an average particle diameter of 0.005 to 15 &mgr;m, and a fluorine base surfactant. An original plate for a lithographic printing plate is disclosed which includes an ordinary negative- or positive-type PS plate having coated thereon the heat-sensitive composition. The original plate is image-wise exposed with high energy density light based on digital image information from a computer, subjected to first development with an aqueous alkali solution, flood exposure with active light, a second development with a developer for a negative or a positive, and post-treatment to obtain a printing plate.

Heat sensitive composition, original plate using the same for lithographic printing plate, and process for preparing printing plate

The present invention relates to a planographic printing plate employed in the field of offset printing, and more particularly, to a preparation method for a printing plate employing a conventional planographic printing original plate with a novel light source. In this method, an image is formed to a planographic printing original plate, in which at least one photosensitive layer sensitive in the region of 300 nm&tilde;450 nm is provided on a substrate, by scan irradiating the plate with high density energy light in the form of the image, and then performing wet development and a post-treatment. This preparation method for the printing plate is characterized in that the output wavelength of the high density energy light is within the range of 300 nm or more, but less than 370 nm, and the high density energy light is high density energy light of the second or third harmonic obtained from a solid-state semiconductor or a solid-state exited by semiconductor. By means of this method, it is possible for an image to be directly drawn stably and at low cost to a conventional planographic printing original plate that was manufactured for an application with active rays, by employing high density energy light that is scan irradiated according to digital information. As a result, high resolution images can be reproduced easily.

Preparation method for printing plate

Growing community of inventors

Tatebayashi, Japan

Shinji Shimizu