Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1997-12-23
2002-09-17
Michl, Paul R. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S221000
Reexamination Certificate
active
06451941
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to a polymerization grade inorganic dispersion stabilizer and a process for producing resinous particles using the stabilizer. More particularly, the present invention relates to a polymerization grade inorganic dispersion stabilizer capable of improving the stability of suspension polymerization during the course of the polymerization and a process for producing by using the stabilizer such resinous particles as have a narrow particle diameter distribution and, when extracted as dry particles, excel in flowability, show no sign of adhesion or coalition, exhibit a good environmental property and, when required to disperse in a liquid, manifest a veritably excellent redispersibility. This invention further relates to a process for producing resinous particles useful as a negatively or positively charged toner for the development of a static charge image. This invention also relates to a process for producing resinous particles useful as a spacer for a liquid crystal display panels and a liquid crystal display panel. This invention further relates to a process for producing resinous particles useful as a spacer for a touch panel. This invention also relates to a process for producing resinous particles useful as conductive particles.
2. Prior Art
The electrophotographic method comprises forming an electric latent image on a sensitive element formed of such an inorganic electrophotographic material as selenium, zinc oxide, or cadmium sulfide or an organic electroconductive material, developing this latent image with a powdery developer, and transferring the developed image to the surface of paper, for example.
Heretofore, the toner for use in the electrophotographic development has been produced generally by solving and stirring and consequently dispersing a coloring agent and other additives (such as charge regulating agent, offset preventing agent, and slip additive) in a thermoplastic resin, solidifying the resultant dispersion, finely pulverizing the solid mixture, classifying the powder, and separating colored minute particles of a preferred particle diameter.
The method which produces the toner by pulverization as mentioned above, however, has various defects. Firstly, it necessitates numerous steps including a step of producing the resin, a step of mixing the resin with the coloring agent and other additives, a step of pulverizing the resultant solid mixture, and a step of classifying the powder and obtaining minute colored particles of a preferred particle diameter and numerous kinds of devices required therefor. As a natural consequence, the toner produced by this method is expensive. Particularly, the step of classifying the powder to obtain a toner having a particle diameter in the optimum range is an indispensable requirement for the formation of an image which abounds in clarity and suffers the phenomenon of fogging only sparingly. It is, however, problematic in terms of productivity and yield. Secondly, the step of mixing encounters extreme difficulty in uniformly dispersing the coloring agent and other additives in the resin. Hence, the toner produced by this method has the property of triboelectrification varied from one particle to another by the inferior dispersion of the coloring agent, the charge regulating agent, etc. This imperfect stability of the property results in degradation of the resolution. These problems will grow increasingly conspicuous in the future owing to the trend of the toner toward a gradual decrease in particle diameter which constitutes an essential requirement for the improvement of the quality of image. The existing pulverizers have their limits in obtaining a toner of a minute particle diameter. Even when they manage to obtain a toner of a minute particle diameter, they nevertheless entail an increase in the inconsistency of the amount of electrification on account of the inferior dispersion of the coloring agent and the charge regulating agent.
For the purpose of eliminating the various defects which are observed in the toner produced by the method of pulverization, methods for producing the toner by the technique of suspension polymerization have been proposed.
These methods are aimed at synthesizing a toner containing a coloring substance with great dispatch by mixing a polymerizable monomer with a coloring substance such as carbon black and other additives and suspension polymerizing the resultant mixture. These methods are capable of eliminating the defects attendant on the conventional method resorting to pulverization. Since these methods embrace absolutely no step of pulverization and therefore obviate the necessity for improving the embrittleness of the produced toner, the toners they produce are formed of spherical particles and excel in flowability and enjoy uniformity of the triboelectrification.
The liquid crystal display panel comprises two electrode substrates, a spacer for uniformly retaining a cell gap between the substrates, and a liquid crystal (LC). When the display panel of this construction is exposed to a back light, the beams of the back light penetrate through the panel in the portions seating the particles of the spacer and consequently lacking the presence of liquid crystal. This leakage of the back light has the problem of degrading the contrast of image and impairing the quality of display. Particularly the STN-LCE dictates perfect repression of the leakage of the back light through the portions seating the spacer particles because it effects the display in a normally black mode.
As a means to curb the leakage of light through the sites of the spacer particles, the method which comprises coloring the spacer particles has been tried. Among the conventional coloring methods are included those methods which use such coloring agents as dyes and pigments.
The methods for attaining coloration with a dye include a method which comprises suspension polymerizing a monomer and a dye (JP-A-05-301,909 refers), for example. The methods for effecting coloration with a pigment include methods which comprise suspension polymerizing a monomer and a pigment (JP-A-07-2,913 and JP-A-09-25,309), for example.
The transparent touch panel which detects a position pressed with a nib of a pen, for example, and emits the detected position in the form of a signal indicating relevant two-dimensional coordinates is combined with the display screen of a liquid crystal display, EL display, plasma display, CRT (Braun tube), etc. and utilized as a device of easy input in numerous fields.
This transparent touch panel has transparent thin-film electrodes formed one each on the surfaces of the transparent substrates thereof and has these electrodes disposed inside as opposed to each other across an intervening space. For the purpose of separating the electrodes as described above, it has been customary to adopt a method which comprises disposing spherical beads as an insulating spacer between the electrodes which are formed on the substrates.
As a means to produce the resinous particles which are used as the insulating space mentioned above, a method which comprises suspension polymerizing a polymerizable monomer may be cited.
The conventional conductive particles comprise polymer particles and a conductive layer formed on the surface of each of the particles. Generally, the conductive particles are used in the electronics packaging field for the purpose of connecting a pair of electrodes. Specifically, a pair of electrodes having the conductive particles interposed therebetween are pressed against each to establish electric connection between the two electrodes through the medium of the conductive particles.
As a means to produce polymer particles destined to form the basis for the conductive particles mentioned above, a method which resides in suspension polymerizing a polymerizable monomer may be cited.
In the production of resinous particles by such methods of suspension polymerization as are utilized in various applications mentioned above, it is difficult from the tec
Ikeda Hayato
Urashima Nobuaki
Fish & Richardson P.C.
Michl Paul R.
Nippon Shokubai Co. , Ltd.
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