Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
1998-04-22
2001-03-06
Rodee, Christopher D. (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S106100, C430S120400, C534S715000, C534S575000
Reexamination Certificate
active
06197467
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toner for developing electrostatic images, a charge control agent comprising an amorphous metal complex salt compound of the monoazo series for control or stabilization of the amount of charges of the toner, and a manufacturing process therefor.
2. Description of the Prior Art
In copying machines, printers and other instruments based on electrophotography, various toners containing a coloring agent, a fixing resin and other substances are used to visualize the electrostatic latent image formed on the photoreceptor having a light-sensitive layer containing an organic or inorganic photoconductive substance.
The chargeability of such toners is a key factor in electrostatic latent image-developing systems. Thus, to appropriately control or stabilize the amount of charges of a toner, a charge control agent providing a positive or negative charge is often added to the toner.
Of the conventional charge control agents in actual application, those providing a negative charge for a toner include 1:2 type metal complex salt dyes of monoazo compounds and metal complexes of aromatic hydroxycarboxylic acids such as alkylsalicylic acids.
However, many of the metal complexes having azo dye structure proposed as charge control agents are usually unstable; for example, they are likely to be decomposed or to deteriorate to lose their initial charge control capability when exposed to mechanical friction or impact, temperature or humidity changes, electric impact, light irradiation, etc. Also, even such metal complexes possessing a practically applicable charge providing property are often problematic as to charge stability or often contain impurity chemicals lacking charge control effect due to differences in production method and conditions, posing many problems regarding charge control agent quality stability, reliability and other aspects.
Among charge control agents capable of resolving these problems are the crystalline metal complex salts having the following structures:
In the above formulas, X represents H (i.e. hydrogen), a halogen, —SO
2
NH
2
, a nitro group, an alkyl group or the like; and A represents H (i.e. hydrogen), an alkali metal, an amine or the like.
Such metal complex salt dyes are what are called 1:2 type azo metal complex dyes wherein 2 molecules of a monoazo dye are coordinated to 1 trivalent metal atom.
The present inventors found problems to be resolved in such 1:2 type azo metal complex dyes, including the possibility that the metal complex dye, when used as a charge control agent in a toner for a long period of time, can damage the photoreceptor by partially exposed crystals on the surface of toner particles because such dye generally possesses hard crystallinity, and the likelihood that the dye tends to drop (separate out) from toner particles during charging (i.e. frictional charging) due to the hard crystallinity.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a charge control agent excellent in charge control properties (charge-providing property and stability), heat resistance and light fastness, good in dispersibility in, and wettability (compatibility) with, toner resins, which is amorphous in nature and hardly damages the photoreceptor when used in a toner, and which is unlikely to drop (separate out) from toner particles during charging, and a manufacturing process therefor.
A second object of the present invention is to provide a toner for developing electrostatic images excellent in environmental resistance (stability of charge control characteristics to changes in temperature and humidity), storage stability (stability over time of charge control characteristics) and durability (charge control characteristic stability in frequently repeated use of toner), good in charge rise property, which contains such a charge control agent that hardly damages the photoreceptor and that is amorphous in nature and unlikely to drop during charging, and which insures stable copy images.
The charge control agent of the present invention is a charge control agent comprising a metal complex salt with a monoazo compound as a ligand, wherein the metal complex salt is amorphous. This charge control agent may be defined as a charge control agent wherein an X-ray diffraction spectrum of the above described metal complex salt demonstrates that the metal complex salt is amorphous.
Also, this charge control agent may be defined as a charge control agent wherein the degree of crystallinity of the above described metal complex salt, as determined by the multiple peak separation method, is not higher than 50% over the 2&thgr; range from 5° to 30° (wherein &thgr; indicates the Bragg angle).
This degree of crystallinity is preferably not higher than 30%.
Also, the charge control agent of the present invention may be defined as a charge control agent wherein the above described metal complex salt is a metal complex salt compound represented by General Formula (I) below:
wherein (R
1
)
0-p
means the presence of 0 to p units of the substituent R
1
;
R
1
represents
an alkyl group that has or does not have a substituent (i.e. that is substituted or unsubstituted),
a cycloalkyl group,
a halogen,
a nitro group,
an alkenyl group,
an aryl group that is subjected to or not subjected to ring (i.e. nuclear) substitution (i.e. that is ring substituted or unsubstituted),
an aralkyl group that is subjected to or not subjected to ring substitution (i.e. that is ring substituted or unsubstituted), or
an —SO
2
N(R
11
)
2
group [in which the 2 units of R
11
, whether identical or not (i.e. the same or different), each represent H (i.e. hydrogen), a lower alkyl group, an aryl group that is subjected to or not subjected to ring substitution, or an aralkyl group that is subjected to or not subjected to ring substitution];
p represents an integer from 1 to 4;
R
2
represents
H (i.e. hydrogen),
an alkyl group that is branched or not branched (i.e. unbranched),
a halogen,
a nitro group,
an alkenyl group,
an aryl group that is subjected to or not subjected to ring substitution (i.e. that is ring substituted or unsubstituted),
an aralkyl group that is subjected to or not subjected to ring substitution (i.e. that is ring substituted or unsubstituted),
—SO
3
L [in which L represents H (i.e. hydrogen), Na, K, NH
4
+
or organic ammonium],
an —SO
2
N(R
11
)
2
group [in which the 2 units of R
11
, whether identical or not, each represent H (i.e. hydrogen), a lower alkyl group, an aryl group that is ring substituted or unsubstituted, or an aralkyl group that is ring substituted or unsubstituted], or
a —CON(R
12
)
2
group [in which the 2 units of R
12
, whether identical or not, represent H (i.e. hydrogen), a lower alkyl group, an aryl group that is subjected to or not subjected to ring substitution (i.e. that is ring substituted or unsubstituted), or an aralkyl group that is subjected to or not subjected to ring substitution (i.e. that is ring substituted or unsubstituted)];
j represents the number of monoazo compound molecules coordinated to the metal M, and specifically 1, 2, 3 or 6;
(M
x+
)
m
represents m units of a metal having an atomic valency of x, m representing 1, 2 or 4; and
(A
+
)
n
represents n units of a neutralizing counter-ion selected from the group consisting of H
+
, NH
4
+
, Na
+
, K
+
and organic ammonium, in which n=2j−mx, such that 2j≧mx (i.e. 2j is greater than or equal to mx), provided that when j=1, and x represents 2, n may be 0 (m thus also being 1).
The central atom of the above described metal complex salt in this charge control agent is preferably an atom of divalent or trivalent metal (e.g., Fe, Co, Zn, Cu, Cr, Al, Ni), more preferably, an iron atom having an atomic valency of 2 or 3, although other central atoms such as tetravalent metal atoms (e.g. Ti, Si) may also be used.
The charge control agent of the present invention, comprising an amorphous metal complex sa
Sukata Kazuaki
Yamanaka Shun-ichiro
Yasumatsu Masashi
McGlew and Tuttle , P.C.
Orient Chemical Industries
Rodee Christopher D.
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