Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-09-05
2004-01-13
Goodrow, John (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S108600, C430S108700, C428S402000, C428S405000
Reexamination Certificate
active
06677095
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high dispersible metal oxide fine powder added in a powder material, such as a coating powder, a toner for an electronic photograph, etc., for the purpose, such as flowability improve, caking prevention, and electrostatic charge control of a powder, and its composite. Specifically, the present invention relates to a high dispersible metal oxide fine powder, which can remarkably improve standup of the electrostatic charge, a image quality, and a cleaning characteristic, by containing said metal oxide fine powder, and to a toner composite containing said powder. In addition, the toner composite of the present invention contains the powder, which is used for not only the electronic photograph but also various electrostatic pictures, such as an electrostatic recording, an electrostatic printing, etc.
BACKGROUND OF THE INVENTION
A developer of the electronic photograph, etc., has comprised the toner composite, in which some external additives are added to the toner, and contained a carrier, for example, a glass bead, an iron powder, or an ferrite carrier, etc., if necessary. As the toner of the external additive, the fine powders are used, which are surface-treated on the metal oxide fine powder, such as fine silica, titania, or alumina, etc., with an organic material, and the flowability and the electrostatic charge of the toner are controlled by this external additive. Especially, the average particle size of the toner has been made fine from about 10 &mgr;m to 5 &mgr;m recently because of the demand of high imaging quality of the electronic photograph. However, there is a problem with this making fine powder, in which the flowability of the toner is decreased, so that is a tendency that the amount of the external additive is increased to improve the flowability of the toner. Moreover, a characteristic of the external additive has been much influenced on the electrostatic charge of the toner by increasing said amount of the additive. For example, if the additive is distributed irregularly in the toner, a high quality development characteristic can not be obtained. For this reason, the additive having good dispersibility is required.
Conventionally, as the external additives of the toner for the electronic photograph, the metal oxide fine powder treated with hydrophobic treatment is used. When the amount of the treatment reagent used is increased to stabilize the surface treatment, it becomes agglomerated the particle, so that the flowability and the dispersibility are decreased on the contrary. Therefore, the process of pulverizing the surface-treated metal oxide powder is proposed. For example, in Japanese Patent Raid Open Hei 2-42452, or Hei 8-152742, the pulverizing to use the surface-treated metal oxide fine powder by a jet mill is shown. However, this pulverizing by the jet mill has high energy cost and, moreover, the particle size after pulverizing is very fine, so that there are problems in dust and handling.
DISCLOSURE OF THE INVENTION
The present invention solves the conventional above-mentioned problems about the metal oxide fine powder used as the external additive of the powder material, such as the toner, etc., and provides the metal oxide fine powder, which has low pulverizing cost, good dispersibility at the time of adding to the powder material, by using the metal oxide fine powder controlled the distribution of the agglomerated particle size according to the average particle size of the powder material, such as the toner etc. Moreover, the present invention also provides the toner composite having the stable electrostatic charge and the good flowability, by containing this metal oxide fine powder.
That is, the present invention relates to the metal oxide fine powder used as the external additive of the powder material, wherein the surface of said powder is hydrophobic treated and has high dispersibility in the powder material by which the peak of the size distribution of the agglomerated particles makes lower than the level of the average particle size of the powder material. Regarding the metal oxide fine powder of the present invention, for example, it is preferable that the average first particle size is less than 300 nm (nano meter), its agglomerated particle has the peak of the particle size distribution in the range of less than 10 &mgr;m (micron meter) preferably 5 &mgr;m, the specific surface area by the BET method is 10-400 m
2
/g, the hydrophobicity is more than 30%, and the bulk density is more than 30 g/L, preferably more than 100 g/L. Moreover, the composition of the metal oxide fine powder is, for example, silica, titania, alumina, zirconia, or these composite oxides, which are hydrophobic treated on the surface with organic silicon compounds. Moreover, the powder material added the metal oxide fine powder of the present invention is, for example, the toner for the powder coating or the electronic photograph. Furthermore, the present invention also relates to the toner composite, which has high flowability by addition with such metal oxide fine powder. It is preferable that the content of the metal oxide fine powder in this toner composite is 0.01-5.0% by weight.
[I] Metal Oxide Fine Powder
The metal oxide fine powder of the present invention is the fine powder, which is silica, titania, alumina, zirconia, a composite oxide of more than two kinds of these metals, or a mixed oxide of more than two kinds of metal oxides. In addition, in the present invention, silica is also included in the metal oxide. The metal oxide fine powder of the present invention is obtained by the surface-treatment with the organic silicon compound, etc., and pulverizing. Furthermore, it is available that the surface treatment and the pulverizing are done simultaneously, before or after.
[II] Surface Treatment
The above-mentioned metal oxide fine powder is hydrophobic treated with the surface treatment reagents, such as the organic silicon compounds. As these surface treatment reagent s, for example, a silicone oil or a silane coupling reagent, such as trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxisilane, dimethylalkoxisilane, methyltrialkoxysilane, and hexamethyldisilazane, etc., an organopolysiloxane or some modified silicone oil including an organopolysiloxane are used. The kind of these silane coupling reagents is not limited, and various kinds of alkoxysilane, chlorosilane, or silazane can be used. Moreover, the kind of the organopolysiloxane is not also limited, so that a dimethyl silicone oil, a methylhydrogene silicone oil, a phenyl silicone oil, a non-reactive silicone oil, or a reactive silicone oil, can be used.
The process and conditions of the surface treatment are not limited. It is available that the conventional surface treatment process is done. For example, an uniform surface modified metal oxide fine powder is obtained by the followings. At first, predetermined amount of the silane coupling agent or the organopolysiloxane is dropped or sprayed onto the metal oxide powder to be dispersed fully with a solvent if necessary. The dispersed powder is stirred at more than 50° C., preferably more than 100° C., more preferably 100° C.-400° C. for 0.1-5 hours, preferably 1-2 hours, and then is cooled.
[III] Hydrophobicity
Regarding the surface treated metal oxide fine powder, it is preferably that the degree of hydrophobicity measured by a transparency method is more than 30%. If the hydrophobicity is less than 30%, the improvement of the moisture resistance or the electrostatic charge stability of the toner is not sufficient when it is used as the external additive of the toner. It is more preferably that the hydrophobicity is more than 60%.
[IV] Particle Size Range
The surface modified metal oxide fine powder of the present invention is used as the external additive of the powder material, wherein the peak of the particle size distribution of the agglomerated particle (the secondary particle) is less than the same level
Morii Toshio
Murota Masamichi
Shirono Hirokuni
Goodrow John
Nippon Aerosil Co., Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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