Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-10-04
2004-06-29
Goodrow, John 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...
C528S272000
Reexamination Certificate
active
06756172
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin binder for a toner used for developing electrostatic latent images formed in electrophotography, electrostatic recording method, electrostatic printing, and the like, preferably a toner for electrophotography, and a toner comprising the resin binder.
2. Discussion of the Related Art
Conventionally, as resin binders for a toner which are excellent in various properties required for copy machines, especially excellent in the low-temperature fixing ability and the offset resistance, there have been known a resin binder prepared by mixing a nonlinear high-softening point resin and a nonlinear low-softening point resin (Japanese Patent Laid-Open Nos. Sho 63-225246, Sho 63-225245, Sho 63-225244, 2000-356865, and the like); a resin binder prepared by mixing a nonlinear high-softening point resin and a linear low-softening point resin (Japanese Patent Laid-Open Nos. Sho 60-214368, Hei 4-362956, 2000-39738, Hei 12-39738, and the like); and the like. However, in the former resin binder, since a nonlinear resin is used as a low-softening point resin, the glass transition point is lowered, so that its storage property is unsatisfactory. In the latter resin, specifying the raw material monomers is insufficient, and the storage property, the pulverizability, and the offset resistance are unsatisfactory.
Further, recently, since network printing has become the main trend for copy machines and printers, further improvement has been desired such as suppression of toner odor to make it environment-friendly upon use in addition to the conventionally required properties such as toner performance and production efficiency during its use in a business office.
An object of the present invention is to provide a resin binder which is excellent in fixing ability, offset resistance, storage property and pulverizability and generates little odor even when used as a resin binder for a toner, and a toner comprising the resin binder.
These and other objects of the present invention will be apparent from the following description.
SUMMARY OF THE INVENTION
According to the present invention, there are provided:
(1) a resin binder comprising a nonlinear polyester having a softening point of from 130° to 160° C. and a linear polyester having a softening point of from 80° to 110° C., wherein the nonlinear polyester is obtained by polycondensing an alcohol component and a carboxylic acid component, wherein
1) an aliphatic dicarboxylic acid compound is contained in an amount of 60% by mol or more of the carboxylic acid component;
2) (i) no alkenylsuccinic acid compound is contained, or
(ii) if any, an alkenylsuccinic acid compound is contained in an amount of 0.1% by mol or less of the carboxylic acid component; and
3) at least one component selected from the group consisting of:
(i) a trihydric or higher polyhydric alcohol in an amount of from 0.1 to 40% by mol of the alcohol component; and
(ii) a tricarboxylic or higher polycarboxylic acid compound in an amount of from 0.1 to 40% by mol of the carboxylic acid component
is contained, and
wherein the linear polyester is obtained by polycondensing an alcohol component and a carboxylic acid component, wherein
1) an aromatic dicarboxylic acid compound is contained in an amount of 90% by mol or more of the carboxylic acid component; and
2) at least one component selected from the group consisting of (a) and (b):
(a)
(i) no trihydric or higher polyhydric alcohol, or
(ii) if any, a trihydric or higher polyhydric alcohol is contained in an amount of less than 0.05% by mol of the alcohol component; and
(b) (i) no tricarboxylic or higher polycarboxylic acid compound, or
(ii) if any, a tricarboxylic or higher polycarboxylic acid compound in an amount of less than 0.05% by mol of the carboxylic acid component
is contained; and
(2) a toner comprising the resin binder of item (1) above.
DETAILED DESCRIPTION OF THE INVENTION
The resin binder of the present invention comprises a nonlinear polyester having a high softening point and a linear polyester having a low softening point. In the present invention, by specifying each of raw material monomers for the nonlinear polyester having a high softening point and the linear polyester having a low softening point, there can be obtained a resin binder for a toner which is not only excellent in fixing ability, offset resistance, storage property and pulverizability but also generates little odor upon heating, thereby making the toner environmental-friendly.
Specifically, the nonlinear polyester is obtained by polycondensing an alcohol component and a carboxylic acid component, wherein
1) an aliphatic dicarboxylic acid compound is contained in an amount of 60% by mol or more of the carboxylic acid component;
2) (i) no alkenylsuccinic acid compound is contained, or
(ii) if any, an alkenylsuccinic acid compound is contained in an amount of 0.1% by mol or less of the carboxylic acid component; and
3) at least one component selected from the group consisting of:
(i) a trihydric or higher polyhydric alcohol in an amount of from 0.1 to 40% by mol of the alcohol component; and
(ii) a tricarboxylic or higher polycarboxylic acid compound in an amount of from 0.1 to 40% by mol of the carboxylic acid component
is contained.
The polyester obtained from an aliphatic dicarboxylic acid compound as a raw material monomer has a higher molecular weight at the same softening point, as compared to the polyester using the aromatic compound. Therefore, despite the low lowest fixing temperature, the polyester is effective in improvement of the offset resistance, so that its performance can be sufficiently exhibited by using the polyester as a main component for the high-softening point polyester.
The aliphatic dicarboxylic acid compound includes oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, acid anhydrides thereof, C
1-3
alkyl esters of these acids, and the like. The aliphatic dicarboxylic acid compound has preferably from 2 to 10 carbon atoms, more preferably 4 to 6 carbon atoms. Incidentally, as described above, the aliphatic dicarboxylic acid compound refers to aliphatic dicarboxylic acids, acid anhydrides thereof and C
1-3
alkyl esters of these acids, among which aliphatic dicarboxylic acids are preferable.
It is desirable that the aliphatic dicarboxylic acid compound is contained in the carboxylic acid component in an amount of 60% by mol or more, preferably from 60 to 99.9% by mol, more preferably from 65 to 90% by mol.
However, a substituted succinic acid of which substituent is an alkenyl group having 2 to 20 carbon atoms, such as dodecenylsuccinic acid and isooctenylsuccinic acid, generates irritable odor upon heat-fixing. Therefore, the content of the substituted succinic acid is preferably as low as possible. Accordingly, no alkenylsuccinic acid compound is contained, or if any, its content in the carboxylic acid component is in an amount of 0.1% by mol or less, preferably 0.05% by mol or less. It is preferable that no alkenylsuccinic acid compound is contained.
As other dicarboxylic acid component, there may be used aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid, acid anhydrides thereof, C
1-3
alkyl esters of these acids, and the like.
Further, in order to form a nonlinear structure and improve offset resistance or the like, there are used trivalent or higher polyvalent monomers, namely trihydric or higher polyhydric alcohol and/or tricarboxylic or higher polycarboxylic acid compound. As the trivalent or higher polyvalent monomers, the tricarboxylic or higher polycarboxylic acid compound is preferable, from the viewpoint of improvement efficiency of the offset resistance.
The tricarboxylic or higher polycarboxylic acid compound includes, for instance, 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, acid an
Ueno Tetsuya
Ueno Yoshihiro
Goodrow John L
Kao Corporation
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