Radiation imagery chemistry: process – composition – or product th – Microcapsule – process – composition – or product
Reexamination Certificate
2001-12-28
2004-11-09
Gilliam, Barbara (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Microcapsule, process, composition, or product
C430S270100, C430S272100, C523S333000, C523S334000
Reexamination Certificate
active
06815137
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for producing polymer fine particles suitable for a lithographic printing plate precursor employing an image forming system wherein polymer fine particles dispersed in a hydrophilic matrix are melted to be coalesced by heating, and also relates to a lithographic printing plate precursor comprising polymer fine particles produced by this production process.
BACKGROUND OF THE INVENTION
Regarding a printing plate for a computer-to-plate system which has remarkably advanced recently, various investigations have been achieved. Among these, for the purpose of further rationalizing a process, i.e., saving one layer and solving a problem of a waste water treatment, has been investigated a lithographic printing plate precursor which can be directly loaded to a printing press to effect printing without being subjected to a developing treatment after exposure, and various methods have been proposed.
One of promising methods is a method using a heat-sensitive lithographic printing plate precursor having a hydrophilic layer (image-recording layer) wherein hydrophobic polymer fine particles are dispersed in a matrix such as a crosslinked hydrophilic resin. When heat is applied to the hydrophilic layer, hydrophobic polymer fine particles are melted to be coalesced so that the surface of the hydrophilic layer is converted to a hydrophobic image area. It has been known that the surface constructed by the hydrophobic image area thus obtained and a hydrophilic non-image area of the hydrophilic resin matrix can be used as a lithographic printing plate using dampening water without requiring a treatment such as a liquid development, i.e., completely being subjected to no treatment.
Has been also known a method using a lithographic printing plate precursor comprising an image-recording layer provided on a support having a hydrophilic surface, obtained by dispersing hydrophobic polymer fine particles in a non-crosslinked hydrophilic matrix, wherein an unexposed area is eliminated on a printing press as if the unexposed area has been subjected to a developing treatment by feeding dampening water and an ink to a plate having been exposed with infrared ray with rotating a cylinder of the printing press (on-press developing method). Namely, the method comprises a plate-making system wherein an exposed printing plate precursor is attached to the printing press without applying any treatment, and a treatment is to be completed during an ordinary printing process, further the surface construction of the printing plate comprises a hydrophobic image area formed upon heating and the hydrophilic surface of the support.
Such a lithographic printing plate precursor suitable for quite no treatment or for the on-press development is attached as it is on a printing press placed in a bright room and is used for printing. Thus, the lithographic printing plate precursor is required to have such a property that it does not cause any problem upon being irradiated with room light (bright room handling property). This bright room handling property has been known to be achieved by utilizing a heat-mode recording wherein exposure to a printing plate precursor is effected with infrared ray and an image is formed with heat generated by the absorption of infrared ray.
For example, in JP-A-7-1849 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”) JP-A-7-1850, JP-A-10-6468 and JP-A-11-70756, is disclosed a heat-sensitive lithographic printing plate precursor comprising a hydrophilic layer having microcapsules including a lipophilic component encapsulated therein as lipophilic (hydrophobic) fine particles dispersed in a crosslinked hydrophilic binder polymer. It is described therein that after applying heat, printing can be effected without effecting any treatment.
Further, in Japanese patent No. 2938397, JP-A-9-127683 and WO 99-10186, is disclosed a lithographic printing plate precursor comprising a heat-sensitive layer (image-recording layer) wherein fine particles of a thermoplastic hydrophobic polymer are dispersed in a hydrophilic binder polymer, provided on a hydrophilic support. It is further described in these publications that in the lithographic printing plate precursor, after forming an image by subjecting fine particles of a thermoplastic hydriphobic polymer to an infrared ray laser exposure thereby to thermally cause coalescence of the fine particles, the plate is attached to a cylinder of a printing press and development on the printing press can be effected with dampening water and/or an ink.
As a production method of polymer fine particles to be used for the heat-sensitive lithographic printing plate precursor, may be exemplified (1) an emulsified polymerization method, (2) a method comprising dispersing a solution obtained by dissolving a hydrophobic polymer in a solvent immiscible with water in an aqueous hydrophilic polymer solution using a surfactant, and (3) a method comprising dispersing a mechanically pulverized polymer with a surfactant. Among these methods, (2) a method wherein a hydrophobic polymer solution is dispersed with a surfactant has been known as a frequently used convenient method.
A conventional method for dispersing a hydrophobic polymer solution in water using a dispersant comprises an orientation of a hydrophobic moiety of the dispersant to the hydrophobic polymer side and also an orientation of a hydrophilic moiety in an aqueous medium. However, it is impossible that the hydrophobic moieties of the dispersant are all forced to be orientated to the polymer side. The hydrophobic moieties are partially orientated in an aqueous medium. Therefore, it is impossible that the surface of polymer fine particles is made highly hydrophilic. A lithographic printing plate precursor using such polymer fine particles has a problem of deficient hydrophilic property in printing, which is readily stained.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve the above problems. Namely, the object of the present invention is to provide a method for producing hydrophobic polymer fine particles having a highly hydrophilic surface.
Another object of the present invention is to provide a lithographic printing plate precursor wherein after exposing the printing plate precursor, it can be attached to the printing press without applying any treatment and can effect printing, and which is improved in staining resistance.
The present inventors have conducted extensive study and research efforts in order to achieve the above-described objects. As the result could be found a process for producing polymer fine particles having a highly hydrophilic surface. Thus, the above-described objects could be achieved.
Namely, it could be found by the present inventors that by the incorporation of an organic silicon group in both a hydrophobic polymer constituting a core part of a polymer fine particle and a hydrophilic resin having dispersibility, a water-soluble resin having a high hydrophilic property is made to effectively function as a dispersant. Thus, it could be found that by utilizing hydrogen bonds derived from silanol groups of both the above-described hydrophobic polymer and the hydrophilic resin, or a firm interaction due to dehydration condensations, a dispersion of polymer fine particles having a highly hydrophilic surface can be stably produced. Thus, the above-described objects could be achieved.
Accordingly, the present invention is as follows:
(1) A process for producing polymer fine particles comprising:
dispersing a solution obtained by dissolving a hydrophobic polymer in a solvent immiscible with water in an aqueous phase comprising fine particles of an oxide or hydroxide of at least one element selected from the group consisting of elements belonging to 2 to 15 groups in the periodic table using a surfactant; or dispersing a solution obtained by dissolving a hydrophobic polymer in a solvent immiscible with water in an aqueous phase comprising a water-soluble resin; and th
Hoshi Satoshi
Kawamura Koichi
Yamasaki Sumiaki
Burns Doane Swecker & Mathis L.L.P.
Fuji Photo Film Co. , Ltd.
LandOfFree
Process for producing polymer fine particles and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing polymer fine particles and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing polymer fine particles and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3315840