Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-11-28
2002-07-02
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S201000, C523S202000, C523S205000, C526S089000, C430S114000, C528S490000
Reexamination Certificate
active
06414052
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns polymeric particles and a production method therefor. More in particular, it relates to polymeric particles which can be used, for example, for marking materials such as ink or toner, decorative materials used for interior or fashion articles use, various kinds of water absorbing materials including disposable diapers, various kinds of spacer materials applied to liquid crystal cells, chemical carriers used for medical use or immobilized enzyme carriers, column packing materials, and cosmetic fillers, as well as a production method therefor.
The polymeric particles obtained according to this invention can be used also as a material capable of controlling the volumic change reversibly in accordance with external stimulations. The material, when incorporated with a colorant, can be utilized for optical devices for controlling the transmission amount of light or sensors, display devices for the display of images and coloring material for recording use.
Further, this invention provides polymeric particles with a narrow particle size distribution and further concerns a process for efficiently producing such polymeric particles. Further, this invention concerns polymeric particles containing a pigment at a high density and in a favorably dispersed state.
2. Description of the Related Art
As a process for producing polymeric particles, a kneading/pulverization method and a polymerization method have been known generally.
The kneading/pulverization method has been utilized generally including a production method of toners used for the developer in electrophotography. Specifically, toners are produced, for example, by kneading under heating those ingredients such as a colorant necessary for the toner dispersed in a binder resin, cooling to solidify the kneading product, pulverizing the same and then classifying and collecting the pulverization product of an appropriate grain size.
On the other hand, various proposals have been made also for the production method of polymeric particles by the polymerization method. For example, various polymerization methods have been known including, for example, a dispersion polymerization method, a suspension (and reversed phase suspension) polymerization method, an emulsion polymerization method, a seed polymerization method and combination thereof. Production of the polymeric particles by the polymerization methods described above is advantageous since they can improve the problem during production of polymeric particles of a size smaller than 10 &mgr;m in the kneading/pulverization method described above, that is, the problem of increasing the pulverizing energy and requiring unnecessary cost in view of the difficulty for the classification.
Research and development have been made vigorously also for the production method of polymeric particles by the polymerization method regarding particles containing a colorant, for example, research and development regarding production of toners. For example, Japanese Published Examined Patent Application No. Sho 51-148995 and Japanese Published Unexamined Patent Application No. Sho 57-53756 disclose a production method for a toner by a suspension polymerization method, Japanese Published Unexamined Patent Application Nos. Sho 60-220358 and Sho 63-205665 disclose a production method for a toner by an emulsion polymerization method. Japanese Published Unexamined Patent Application No. Hei 3-229268 discloses a production method for a toner by a dispersion polymerization method. Japanese Published Unexamined Patent Application Nos. Sho 60-258203, Hei 5-222109, Hei 5-262809, Hei 5-271312 and Hei 5-303231, etc. disclose a production methods for a toner by a seed polymerization method, respectively.
Further, according to the contents of the disclosure described above, colorless or transparent polymeric particles can be obtained easily by not incorporating the colorant.
On the other hand, for polymeric particles not containing the colorant, a production method for water absorbing polymeric particles, for example, by a reversed phase suspension polymerization method has been well known and various proposals have been made. For example, production of water absorbing resin particles having a grain size of about 10 to 100 &mgr;m has been shown, for example, in Japanese Published Examined Patent Application No. Sho 54-30710 by using a sorbitan fatty acid ester having HLB of 3 to 6 as a dispersant, in Japanese Published Unexamined Patent Application No. Sho 57-167302 by using a nonionic surfactant having HLB of 6 to 9 as a dispersant, and in Japanese Published Examined Patent Application No. Sho 60-25045 by using a surfactant having HLB of 8 to 12 as a dispersant. In addition, Japanese Published Examined Patent Application No. Sho 63-36321 and Japanese Published Examined Patent Application No. Sho 63-36322 discloses that water absorbing resin particles having a grain size of about several hundred &mgr;m by using an oleophilic carboxyl group-containing polymer as a dispersant. Further, Japanese Unexamined Patent Application No. Sho 62-172006 discloses that polymeric particles of large particle size can be obtained by using a polyglycerin fatty acid ester having HLB from 2 to 16 as a dispersant.
However, any of the processes for producing polymeric particles by the various kinds of polymerization methods described above involves a problem that efficient production of particles of a narrow grain size distribution is generally difficult. Further, even when particles of a narrow grain size distribution can be obtained, this generally requires a great amount of dispersing medium and the production efficiency is extremely poor.
Further, in the case of the emulsion polymerization method or the seed polymerization method, the applicable grain size is 3 &mgr;m or smaller while the grain size distribution can be narrowed relatively. In the suspension polymerization method, since the grain size distribution cannot be narrowed, it is difficult in the application to the manufacture of polymeric particles at a grain size of from several &mgr;m to several tens &mgr;m which is necessary in the use of the particles as the display material.
In addition, there is also a problem that it is difficult to incorporate a colorant at a high density. For example, since it is difficult, in principle, to incorporate a colorant ingredient in the emulsion polymerization method and the dispersion polymerization method, it is generally required for an additional step of composing the polymeric particles after formation with the colorant ingredient as disclosed, for example, in Japanese Published Unexamined Patent Application Nos. Hei 1-44456, Hei 2-302761, and Hei 5-222109. However, this method involves a problem that the production step is complicated and the production cost is increased, as well as increase of content of the colorant is difficult.
On the other hand, the suspension polymerization method is, typically, a method of finely particulating liquid droplets of non-aqueous radial polymerizable monomers together with a suspension stabilizer in an aqueous medium by external mechanical shearing force and polymerizing the resultant monomer liquid droplets using an initiator to form solid particles. Since other ingredients than the monomer can easily be incorporated into the monomer liquid droplets by this method, colored particles can be prepared relatively easily. However, the monomer density in the dispersing medium has to be set to a relatively lower level, so that it requires a great amount of a dispersant. Accordingly, this requires considerable production cost and also results in a problem of poor production efficiency.
Further, use of a great amount of the dispersant is not preferred also in view of the reduction of environmental burdens and resource preservation. On the other hand, it may be considered to use a production facility capable of reutilizing the dispersant but this results in a problem of further increasing the production cost.
On the other hand, the pre
Akashi Ryojiro
Kawahara Jun
Komura Akinori
Moriyama Masahiro
Uematsu Takashi
Fuji 'Xerox Co., Ltd.
Yoon Tae H.
LandOfFree
Polymeric particles and production method thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polymeric particles and production method thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polymeric particles and production method thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2873162