Direct drawing type lithographic printing plate precursor

(54) DIRECT DRAWING TYPE LITHOGRAPHIC PRINTING PLATE PRECURSOR

(75) Inventors: Hiroshi Tashiro; Eiichi Kato, both of Shizuoka (JP)

(73) Assignee: Fuji Photo Film Co., Ltd., Kanagawa (JP)

( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.

(21) Appl. No.: 09/464,575

(22) Filed: Dec. 16, 1999

(30) Foreign Application Priority Data

Dec. 17, 1998 (JP) 10-359383

(51) Int. C I. B41C 1/10

(52) U.S. CI 101/455; 101/466; 430/49;

428/446

(58) Field of Search 101/453, 454,

101/455, 457, 462, 460, 463.1, 465, 466;

430/49; 428/148, 446, 447, 689

(56) References Cited

U.S. PATENT DOCUMENTS

5,582,106 * 12/1996 Kanda et al 101/462

5,607,533 * 3/1997 Kato 101/467

5,677,098 * 10/1997 Nakayama et al 430/95

5,714,250 * 2/1998 Kato et al 428/328

5,795,690 * 8/1998 Takegawa et al 430/58.25

5,852,975 * 12/1998 Miyabe et al 101/463.1

6,019,045 * 2/2000 Kato et al 101/466

6,098,545 * 8/2000 Kato 101/465

6,117,552 * 9/2000 Hanada et al 428/411.1

6,120,655 * 9/2000 Ishii et al 101/463.1

6,152,037 * 11/2000 Ishii et al 101/466

FOREIGN PATENT DOCUMENTS

204355 * 8/1998 (JP) .

* cited by examiner

Primary Examiner—Stephen R. Funk

(74) Attorney, Agent, or Firm—Reed Smith LLP

(57) ABSTRACT

A direct drawing type lithographic printing plate precursor comprising a water-resistant support having provided thereon an image-receiving layer, the image-receiving layer being formed from a dispersion comprising: an inorganic pigment comprising silica particles having an average particle diameter of from 1 to 6 fim and ultra-fine particles of inorganic pigment having an average particle diameter of from 5 to 50 nm, at a weight ratio thereof of from 40:60 to 70:30; and a hydrophilic binder resin comprising at least one modified hydrophilic binder resin which is modified with a silyl functional group represented by the following formula (I):

1

DIRECT DRAWING TYPE LITHOGRAPHIC
PRINTING PLATE PRECURSOR

FIELD OF THE INVENTION

The present invention relates to a direct drawing type 5 lithographic printing plate precursor, and more particularly to a direct drawing type lithographic printing plate precursor suitable for use in the field of small-scale commercial printing.

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BACKGROUND OF THE INVENTION

Lithographic printing plate precursors which are presently used in the field of small-scale commercial printing include (1) a direct drawing type printing plate precursor having a hydrophilic image-receiving layer provided on a water- 15 resistant support, (2) a printing plate precursor of an electrophotographic light-sensitive material having a photoconductive layer provided on a water-resistant support, the photoconductive layer comprising photoconductive zinc oxide and is converted into a printing plate by undergoing 20 image formation and then desensitizing treatment with a desensitizing solution to render the non-image area hydrophilic, and (3) a printing plate precursor of a silverhalide photographic material having a silver halide emulsion layer provided on a water-resistant support. 25

With the development of office appliances and the expansion of office automation in recent years, it has been desired in the field of small-scale printing to adopt an offset printing system wherein a lithographic printing plate is directly prepared from a direct drawing type lithographic printing 30 plate precursor (the foregoing (1)) utilizing various image forming means, e.g., an electrophotographic printer, a heatsensitive transfer printer or an ink jet printer without undergoing any other special treatment for conversion into the printing plate. 35

A conventional direct drawing type lithographic printing plate precursor comprises a support such as paper having on one surface side an image-receiving layer which is a surface layer provided via an interlayer and on the other surface side a back layer. The interlayer and the backlayer are each 40 composed of a water-soluble resin such as PVA or starch, a water-dispersible resin such as a synthetic resin emulsion, and a pigment. The image-receiving layer comprises an inorganic pigment, a water-soluble resin and a water resisting agent 45

Examples of inorganic pigment conventionally used include kaolin, clay, talc, calcium carbonate, silica, titanium oxide, zinc oxide, barium sulfate and alumina.

Examples of water-soluble resin used include polyvinyl 50 alcohol (PVA), modified PVA such as carboxylated PVA, starch and derivatives thereof, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, casein, gelatin, polyvinyl pyrrolidone, vinyl acetate-crotonic acid copolymer, and styrene-maleic acid copolymer. 55

Examples of water resisting agent used include glyoxal, initial condensates of aminoplasts such as melamineformaldehyde resin and urea-formaldehyde resin, modified polyamide resins such as methylolated polyamide resin, polyamide-polyamine-epichlorohydrin adduct, polyamide 60 epichlorohydrin resin, and modified polyamide-polyimide resin.

In addition to the above described ingredients, it is known that a cross-linking catalyst such as ammonium chloride or a silane coupling agent can also be used. 65

In recent plate-making system using various kinds of printers, it is required for an image-receiving layer of the

2

printing plate precursor to have both hydrophilicity sufficient for preventing the occurrence of stain due to adhesion of printing ink and water resistance as a lithographic printing plate, and sufficient adhesion to oleophilic images formed thereon. Various proposals have been made in order to satisfy the requirement.

For instance, a proposal has been made to improve the hydrophilicity and image adhesion by the application of an image-receiving layer prepared by dispersing zinc oxide, kaolinite and alumina as inorganic pigments together with a water-soluble resin, a water resisting agent and acetic acid whereby zinc oxide reacts with acetic acid to form zinc acetate, and coating the resulting dispersion as described in JP-A-63-54288 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). It is also proposed that the hydrophilicity and water resistance are improved by employing the same image-receiving layer described above except that talc or silica is used in place of alumina and an aluminum-based, zirconium-based or titanium-based metal compound is used as the water resisting agent as described in JP-A-63-166590 and JP-A-63166591.

Also, in case of employing an electrophotographic printer using a dry toner (PPC coping machine) for plate- making, the toner undesirably adheres to non-image area of the resulting printing plate, which forms background stain on prints, when the printing plate is subjected to printing. In order to overcome the problem, a method for controlling surface roughness of the image-receiving layer to a specific range using an organic pigment such as silica having an average diameter of from 5 to 20 Hm as described in JP-B-6-96353 (the term "JP-B" as used herein means an "examined Japanese patent publication") and a method of using as organic pigment, both silica and alumina sol each having an average diameter of from 5 to 20 pm as described in JP-A-62-157058 are proposed.

Further, as an approach for preventing stain occurrences in the non-image area due to the adhesion of ink and increasing adhesion of an ink image to the image-receiving layer during plate-making using a PPC copying machine or a heat-sensitive transfer printer, a method of using colloidal silica having a particle diameter of not more than 20 nm, a pigment such as calcium bicarbonate and a lubricant such as polyethylene wax emulsion in combination as described in JP-A-6-183164, and a method of using synthetic silica powder having a particle diameter of not more than 20 pm, a colloidal silica having a particle diameter of not more than 50 nm and a hydrophilic polyvinyl alcohol resin as described in JP-B-5-17871, are proposed.

On the other hand, the recent spread of various office automated machines, various computers and peripheral appliances thereof and the development of related technology as described above have made it possible to form an image by compilation using a personal computer or a workstation and to output the digital signal of the image directly on a lithographic printing plate precursor from a printer capable of processing digital signal, thereby preparing a printing plate. Also, as a printer capable of processing digital signal which can provide highly accurate images compared with those hitherto known, a laser printer using a dry toner having a particle diameter of from 7 to 8 gm, an ink jet printer of electrostatic ejection type which ejects oil-based ink in the electrostatic field to form an image, and the like have been developed.

However, direct drawing type lithographic printing plate precursors prepared according to conventional techniques