Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-12-15
2003-12-02
Dote, Janis L. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S108100, C430S108400, C430S109300, C430S110200, C430S110300, C430S110400, C430S111400, C430S137110, C430S137140, C430S137170
Reexamination Certificate
active
06656653
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a toner for the development of an electrostatic image, particularly for use in electrophotographic process copying machines and printers. More particularly, the present invention relates to a toner for the development of an electrostatic image prepared by emulsion polymerization agglomeration method.
BACKGROUND OF THE INVENTION
A conventional toner for the development of an electrostatic image which has previously been widely used in electrophotography has been prepared by a process which comprises melt-kneading a mixture of a binder resin such as of a syrene-acrylate copolymer, or polyester, a colorant such as carbon black and a pigment, a charge control agent and/or a magnetic material through an extruder, grinding the material obtained, and then classifying the resulting powder. However, the conventional toner obtained by such a melt-kneading/grinding process has the disadvantage that the controllability of the particle diameter of the toner is limited, making it difficult to prepare a toner substantially having an average particle diameter of not more than 10 &mgr;m, particularly not more than 8 &mgr;m in a good yield. Thus, the conventional toner cannot be considered good enough to provide the high resolution that will be required in the future electrophotography.
In order to achieve oilless low temperature fixability, an approach involving the blend of a low softening wax in a toner during kneading has been proposed. In the kneading/crushing process, however, the amount of wax to be blended is limited to about 5% by weight. Thus, toners having sufficient low temperature fixability and OHP transparency cannot be obtained.
In an attempt to overcome difficulty in controlling the particle diameter and hence realize high resolution, JP-A-63-186253 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”) proposes a process for the preparation of a toner involving emulsion polymerization/agglomeration process. However, this process is also limited in the amount of wax that can be effectively introduced into the agglomeration step. Thus, this process leaves something to be desired in the improvement in oilless low temperature fixability.
JP-A-9-190012 proposes a process for the preparation of a toner involving emulsion polymerization/agglomeration process using crosslinked primary polymer particles for suppressing gloss in a formed image. However, this process provides an image with insufficient OHP transparency.
In JP-A-8-50368, a toner is disclosed containing a low melting point ester-based wax. Specifically, however, the toner described in this publication is produced by suspension polymerization. The particle size distribution of the toner is difficult to control due to the production process. Thus, it is difficult to obtain a high resolution image with this toner. In JP-A-10-301322 a toner is disclosed containing a low melting point ester-based wax produced by an emulsion polymerization agglomeration process. The toner described in this publication, however, comprises an uncrosslinked binder resin. Further, OHP transparency and offset resistance of the toner are not sufficient.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to overcome the difficulties of the conventional toner for the development of an electrostatic image.
It is a further object of the present invention to provide a toner having high resolution, oilless fixability, and sufficient low temperature fixability, offset resistance, blocking resistance, fixing temperature width and OHP transparency.
It is a further object of the present invention to provide a process for producing such a toner. These and other objects of the present invention have been satisfied by the discovery of an emulsion polymerization agglomeration toner comprising a low melting point wax and using primary polymer particles and/or particulate resin having a specified crosslinking degree, and the process for producing the same.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to a toner or the development of an electrostatic image comprising an agglomerate of particles obtained by agglomerating a mixture comprising (i.e. at least) primary polymer particles and primary colorant particles, wherein an insoluble content in tetrahydrofuran (the THF insoluble content) of the toner is from 15% to 80 w/w (all percentages are w/w % unless otherwise indicated) and the toner comprises wax having a melting point of 30 to 100° C.
The present invention further relates to a toner for the development of an electrostatic image comprising an agglomerate of particles obtained by agglomerating at least primary polymer particles and primary colorant particles, wherein the THF insoluble content of the primary polymer particles is from 15% to 70 w/w % and the toner comprises wax having a melting point of 30 to 100° C.
A further embodiment of the present invention relates to a toner for the development of an electrostatic image comprising an agglomerate of particles obtained by agglomerating at least primary polymer particles and primary colorant particles, wherein a proportion of a polyfunctional monomer in monomer components constituting the primary polymer particles is 0.005 to 5 w/w % and the toner comprises wax having a melting point of 30 to 100° C.
An additional embodiment of the present invention relates to a method for producing a toner for the development of an electrostatic image comprising agglomerating at least primary polymer particles and primary colorant particles to form an agglomerate of particles, wherein the primary polymer particles are produced by emulsion polymerization of a monomer mixture comprising 0.005 to 5 w/w % of a polyfunctional monomer, and the toner comprises wax having a melting point of 30 to 100° C.
The toner according to the present invention comprises wax, primary polymer particles and primary colorant particles, and, if necessary, comprises one or more of a charge control agent, particulate resin and other additives. The toner of the present invention is produced by an emulsion polymerization agglomeration method. According to the emulsion polymerization agglomeration method, the toner is produced by co-agglomerating at least primary polymer particles obtained by emulsion polymerization, and primary colorant particles and, depending upon necessity, primary charge control agent particles and particulate resin.
Further, in the toner of the present invention the resin constituting primary polymer particles and/or particulate resin is preferably crosslinked and a low melting point wax is preferably included in the toner.
Wax
The wax used in the present invention, can be any conventional wax having a melting point of 30 to 100° C. Examples of such waxes include olefinic waxes such as low molecular weight polyethylene, low molecular weight polypropylene and polyethylene copolymer; paraffin waxes; ester-based waxes having a long-chain aliphatic group such as behenyl behenate, montanic acid ester and stearyl stearate; vegetable waxes such as hydrogenated castor oil and carnauba wax; ketones having a long-chain alkyl group such as distearyl ketone; silicones having an alkyl group; higher aliphatic acids such as stearic acid; long-chain aliphatic alcohols such as eicosanol; carboxylic acid esters of polyhydric alcohols such as glycerol and pentaerythritol, and long chain aliphatic acids or partial esters thereof; and higher aliphatic acid amides such as oleic acid amide and stearic acid amide; and low molecular polyesters.
Among these waxes, those having a melting point of not less than 40° C. are preferred, with a melting point of not less than 50° C. being more preferred to improve the fixability of the toner. Further, it is preferred that the wax have a melting point of not higher than 90° C., more preferably not higher than 80° C. If the melting point of wax is too low, the wax may be exposed on the surface of the toner after fixing, which is liable to produce a sticky feel. On th
Ando Osamu
Ishikawa Tomoko
Mitsuhashi Kazuo
Takahashi Noriaki
Xu Yuqing
Dote Janis L.
Mitsubishi Chemical Corporation
LandOfFree
Toner for the development of electrostatic image and method... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Toner for the development of electrostatic image and method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Toner for the development of electrostatic image and method... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3119840