Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2001-07-10
2002-09-03
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...
C430S111400
Reexamination Certificate
active
06444388
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toner for an electrostatic latent image used for the electrophotography and the like.
2. Description of the Related Art
Provided as a toner binder having a good offset resistance while maintaining a low temperature fixability in Japanese Patent Application Laid-Open No. 2000-29245 is a toner binder for developing an electrostatic latent image comprising a resin having a THF-insoluble content of 2 to 60% by weight which is obtained by reacting a cross-linked polyester resin of carboxylic acids, diols and a novolak type resin with oxyalkylene ether with at least one epoxy compound selected from the group consisting of a novolak type epoxy resin and an epi-bis type epoxy resin.
The toner binder described above is excellent in an offset resistance, a low temperature fixability and an environmental dependency and has the effects that it has less change in a charging amount even under various environments and that the reactivity in producing the binder is high and can easily be controlled.
However, when carrying out a copying operation with, a copying apparatus charged with a toner using the polyester resin produced the method described above, it is possible to obtain a toner which is excellent in an offset resistance, a low temperature fixability and an environmental dependency, but there has been the problem that an offensive odor is generated when an image-forming toner on a copying paper is passed through a fixing unit. Further, there has been the problem that a surface of a cooling unit is stained in a cool-solidifying step after melting and kneading.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a toner which does not bring about the problems of generation of an offensive odor and a stain on a surface of a cooling unit in a cool-solidifying step and which is excellent in an offset resistance, a low temperature fixability and an environmental dependency.
Intensive investigations repeated by the present inventors have resulted in finding that dimethyl terephthalate which is an OH terminal masking agent for dicarboxylic acids remaining in the polyester resin without reacting takes part in an offensive odor and that a content of dimethyl phthalate which causes an offensive odor has a threshold value. Further, they have found out that this dimethyl phthalate causes principally a stain on a surface of a cooling unit, and they have completed the present invention.
That is, the present invention relates to a toner for developing an electrostatic latent image comprising a polyester resin. as a principal component which is formed by reacting dicarboxylic acids of a polybasic acid with diols of a polyhydric alcohol, wherein dimethyl phthalate remaining in the polyester resin described above without reacting has a content of 0.1% by weight or less.
Further, the present invention relates to an image-forming method or an image-forming apparatus using the toner for developing an electrostatic latent image described above.
In the toner for developing an electrostatic latent image of the present invention,
(1) the polyester resin described above has preferably an acid value of 15 to 33 mg KOH/g,
(2) the polyester resin described above has preferably a hydroxyl group value of 10 to 30 mg KOH/g,
(3) the polyester resin described above has preferably a glass transition temperature (Tg) of 55 to 65° C.,
(4) the polyester resin described above has preferably a 4 mm descending temperature (flow tester constant rate-heating method) of 155 to 170° C.,
(5) the polyester resin described above has preferably a number average molecular weight (Mn) of 4500 to 7000,
(6) the polyester resin described above has preferably a tetrahydrofuran (THF)-insoluble content of 20 to 40% by weight,
(7) a fluidizer particle is preferably added to the surface of the toner described above and mixed therein,
(8) the fluidizer particle is preferably added and mixed in an amount of 0.1 to 3% by weight based on the whole amount of the toner.
DESCRIPTION OF THE INVENTION
The toner for developing an electrostatic latent image of the present invention comprises a polyester resin as a principal component. The polyester resin used in the present invention is a polymer which is obtained by polycondensation of a polybasic acid with a polyhydric alcohol and which is combined through ester bonds and includes either saturated or unsaturated polymer. The kind of the polyester resin shall not specifically be restricted and includes, for example, various resins such as an unsaturated polyester resin, an alkid resin, polyethylene terephthalate, polybutylene terephthalate, polyarylate and the like, and an unsaturated polyester resin is particularly preferred.
The polybasic acid constituting the polyester resin shall not specifically be restricted, and preferably used as carboxylic acids are, for example, aliphatic dicarboxylic acids (examples: maleic acid, fumaric acid, succinic acid, adipic acid, sebacic acid, malonic acid, azelaic acid, mesaconic acid and citraconic acid), aromatic dicarboxylic acids (examples: phthalic acid, isophthalic acid and terephthalic acid), alkyl or alkenyl succinates (examples: dodecenyl succinate, pentadodecenyl succinate and the like), anhydrides and lower alkyl esters of these dicarboxylic acids. More preferred are maleic acid, fumaric acid, isophthalic acid, terephthalic acid, dimethyl terephthalate and dodecenyl succinate.
The polyhydric alcohol shall not specifically be restricted, and the diols include, for example, various ones such as alkylene glycols (examples: ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,5-pentanediol and 1,6-pentanediol), alkylene ether glycols (examples: diethylene glycol, triethylene glycol, dipropylene glycol and polyethylene glycol), alicyclic diols (examples: hydrogenated bisphenol A and the like) and bisphenols (examples: bisphenol A, bisphenol F, bisphenol S and the like). The kinds of these polybasic acids and polyhydric alcohols may be either one kind or two or more kinds respectively.
The polyester resin used in the present invention has preferably an acid value of 15 to 33 mg KOH/g (based on JIS K0070-1966) and a hydroxyl group value of 10 to 30 mg KOH/g (based on JIS K0070-1916). In this case, the acid value is an index for the number of residual carboxyl groups at the terminals of the polyester resin, and the hydroxyl group value is an index for the number of residual hydroxyl groups at the terminals of the polyester resin. The acid value can be increased by elevating a use proportion of a polybasic acid (for example, trimellitic anhydride) rather than a dibasic acid in the polyester resin, and the hydroxyl group value can be controlled by reducing terminal groups in the alcohol components. The acid value can be elevated by, for example, adding 1 to 5% of maleic anhydride and 1 to 5% of trimellitic anhydride. Further, the hydroxyl group value can be controlled in the range described above by controlling terephthalic acid in a trace amount.
A polyester resin using polybasic acid having an aromatic ring and polyhydric alcohol has a good blocking resistance and therefore is preferred. In particular, preferred is a polyester resin prepared by reacting aromatic dicarboxylic acid or carboxylic acid including a derivative thereof with diols.
The polyester resin of the present invention can be obtained usually by using the raw material components described above to carry out dehydration condensation reaction or transesterification in an organic solvent in the presence of a catalyst. In this case, the reaction temperature is, for example, 150 to 300° C.
In carrying out the reaction described above, an esterification catalyst and a transesterification catalyst, for example, magnesium acetate, zinc acetate, lead acetate and antimony trioxide can be used for the purpose of accelerating the reaction.
In the present invention, an increase in the amounts of, for example, maleic anhydride a
Murakami Toshihiko
Nagahama Hitoshi
Sumida Katsuaki
Alexander John B.
Conlin David G.
Goodrow John
Sharp Kabushiki Kaisha
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