Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2001-10-24
2003-05-13
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...
Reexamination Certificate
active
06562536
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a charge-controlling agent for controlling chargeabilities of toners used for electrophotography, electrostatic recording, electrostatic printing, and the like. The invention also relates to a toner using the charge-controlling agent.
BACKGROUND OF THE INVENTION
In copying machines and printers utilizing the principle of electrophotography, a developing method is employed wherein a dry toner charged beforehand is fed to an electrostatic latent image formed on an electrophotographic photosensitive body to form a visible image. Generally, in the dry toner, the surface of toner particles is charged by friction between the toner particles in the case of single-component system in which a magnetic powder such as iron powder is internally incorporated into the toner particles. In the case of two-component system, the surface of toner particles is charged by mixing and stirring toner particles with a magnetic powder. Charging properties such as initial chargeability, stability of charge-level with the lapse of time, and saturated charged amount of the toner particles considerably affect the quality of electrostatic print. Therefore, for controlling always these physical properties and maintaining a stable state, a positively chargeable or negatively chargeable charge-controlling agent is frequently added in toner particles at the production of the particles.
As a charge-controlling agent which imparts chargeability to black toners, nigrosine has been hitherto employed. However, nigrosine has a strong coloring power and adversely affects hue of color except black, so that it is difficult to apply it to color toners whose demand has been recently increasing.
Moreover, safety requirement of chemical substances becomes gradually severe in recent years. Even in the case of charge-controlling agent, it is required to reduce volatile organic compounds (VOC) as much as possible, which generate upon kneading with a toner resin or upon actual high-speed printing on a copying machine. However, nigrosine contains a trace amount of aniline and complete removal of aniline is difficult, so that there is a possibility that the use of nigrosine containing a trace amount of smelly and harmful aniline may be regulated in future.
As charge-controlling agents other than nigrosine, there are mentioned, for example, quaternary ammonium salts disclosed in JP-A-62-53944 (corresponding to U.S. Pat. Nos. 4,683,188 and 4,780,553)(The term “JP-A” used herein means an “unexamined published Japanese patent application”) and JP-A-3-27052, a polyamine having a repeating unit wherein a pyrrole ring or phenylimino group and a piperazine ring or imino group are bonded through methylene group described in JP-A-51-9456 (corresponding to U.S. Pat. No. 4,021,358), a polyamine having a repeating unit wherein a phenylimino group and a piperazine ring are bonded through methylene group described in JP-A-58-171060, and a polyamine selected from the group consisting of poly(phenylimino) and poly(alkylimino) disclosed in JP-A-6-348061 (corresponding to U.S. Pat. No. 5,491,043).
The quaternary ammonium salts disclosed in JP-A-62-53944 (corresponding to U.S. Pat. No. 4,780,553) and JP-A-3-27052 are colorless or light in color, so that it is possible to employ them as charge-controlling agents. However, these compounds have drawbacks that thermal stability is insufficient and thus, the compounds tend to cause thermal decomposition and coloring, when kneading with a binder resin for toner, and also chargeabilities are considerably inferior as compared with nigrosine.
Moreover, the polyamine disclosed in JP-A-6-348061 (corresponding to U.S. Pat. No. 5,491,043) has a drawback that it is a compound having a low melting point and thus, tends to be colored, when kneading with a toner resin, and therefore, it is difficult to employ it as a charge-controlling agent for color toners. Furthermore, the polyamines disclosed in JP-A-51-9456 (corresponding to U.S. Pat. No. 4,021,358) and JP-A-58-171060 cause almost no coloring but have drawbacks that thermal decomposition occurs, when kneading with a binder resin for toner, they have considerably poor dispersibility in a toner resin, and they are not always excellent in chargeabilities. As described above, there has not yet been found a charge-controlling agent which is colorless or light in color, has excellent chargeabilities, is applicable to color toners, and also emits only a little amount of VOC.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide a charge-controlling agent which can be applied to not only black toners, but color toners, emits only a little amount of VOC, and is excellent in chargeabilities, particularly in charged amount and stability of charge-level.
Another objective of the present invention is to provide a toner comprising the charge-controlling agent.
Other objectives and effects of the present invention will become apparent from the following description.
For solving the above problem, the invention provides:
(1) a charge-controlling agent comprising a polyamine having a repeating structure represented by the following general formula (I):
wherein R
1
to R
4
each independently represents an alkyl group having 1 to 4 carbon atoms or hydrogen atom, n represents 0 or 1, and
when n=0, R
5
represents an alkylene group having 4 to 15 carbon atoms, which may have a substituent selected from the group consisting of alkyl groups having 1 to 4 carbon atoms and phenyl group, and
when n=1, A represents a phenylene group in which the hydrogen atom(s) on the ring may be replaced by alkyl group(s) having 1 to 4 carbon atoms, and R
5
and R
6
each independently represents an alkylene group having 1 to 8 carbon atoms, provided that the sum of the carbon atoms of the alkylene groups represented by R
5
and R
6
ranges from 2 to 9.
DETAILED DESCRIPTION OF THE INVENTION
The charge-controlling agent of the invention comprises a polyamine having a repeating structure represented by the above general formula (I). In the above general formula (I), R
1
to R
4
each independently represents an alkyl group having 1 to 4 carbon atoms or hydrogen atom, and n represents 0 or 1.
In the case that n is 0, R
5
represents an alkylene group having 4 to 15 carbon atoms, which may have a substituent selected from the group consisting of alkyl groups having 1 to 4 carbon atoms and phenyl group. Examples of such a case of R
5
include linear alkylene groups such as butylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, tridecamethylene group, tetradecamethylene group, and pentadecamethylene group; alkylene groups in which part of hydrogen atoms is replaced by substituent(s) selected from the group consisting of methyl group, ethyl group, propyl group, butyl group, and phenyl group; and the like. Among these alkylene groups, preferred is a linear alkylene group having 4 to 15 carbon atoms, and particularly preferred is a linear alkylene group having 6 to 12 carbon atoms.
In the above general formula (I), two or more of R
5
may be the same or different from each other in the case that n is 0. Also, the polyamine may be a polyamine wherein two or more of R
5
is composed of a combination of a small amount of an alkylene group having a small number of carbon atoms such as methylene group, ethylene group, or propylene group and an alkylene group having a large number of carbon atoms such as hexamethylene group or decamethylene group. However, in such a combination case, the use of too high ratio of methylene group results in a polyamine which has a high melting point and is very hard, so that the dispersibility into a binder resin tends to be poor in the kneading process. Also, the use of too high ratio of ethylene group or propylene group results in a polyamine which has strong hydrophilicity owing to piperazine group and thus strong affinity with water, so that the polyamine
Fujii Keiichi
Ganbayashi Hideki
Armstrong Westerman & Hattori, LLP
Dainippon Ink and Chemicals Inc.
Goodrow John
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