Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-12-07
2002-08-13
Goodrow, John (Department: 1753)
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
06432600
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toner for electrophotography. More specifically, the present invention relates to a binder resin having high electric power efficiency and excellent resin strength, which may be used for a toner for electrophotography.
2. Description of Related Art
Recently, copying machines and printers which utilize an electrophotography system have been widely used in many places and, as their applications increase, the demand for low electric power consumption and easy treatment of a waste toner has been increased. As for the toners used for electrophotography, one that has an excellent fixing property to a transfer medium even at low fixing temperatures and no need to be treated as a waste product after its use has been awaited. Also, toners that generates no hazardous volatile gases during the thermal fixing process has been demanded.
Conventionally, in order to improve the fixing strength of a toner for electrophotography, a binder resin having low molecular weight has been utilized. Also, attempts have been made to lower the glass transition temperature of the toner to decrease the softening temperature thereof.
However, when a binder resin of low molecular weight is used for toners, although the softening temperature of the toner is lowered, its melting viscosity is also lowered which causes a decrease in durability and an offset for a thermal fixing roller. In order to eliminate the occurring of offset, the addition of releasing agents such as waxes having a low melting point has been examined. However, such effect can only be achieved with sacrifice of durability such as fluidity, anti-fusing property, and anti-spent property of toner.
Also, although a styrene-acryl copolymer has been conventionally used as a binder resin for toners, there is a problem that hazardous chemicals such as styrene and xylene used in the polymerization process remain in the final product. In order to solve this problem, the efficiency of the polymerization process has been increased and the washing process of the resin after polymerization has been intensified. However, in consideration of their performance and required costs, these cannot be regarded as the best ways.
Moreover, if polyester resin is used, the fixing property of the toner at low temperatures is insufficient.
Further, although waste toner from copying machines and printers of the electrophotography systems are being collected by contractors recently, most of the collected toner is incinerated or buried as industrial wastes. Also, the handling of an all-in-one type toner cartridge containing a developer and a waste toner box is troublesome when it is recycled.
In addition, toners used for full-color printers which have rapidly increased in popularity are sensitive to mechanical stress due to an increase in printing process speed. Especially, sharp melt type toners which are designed to attain high gloss have a large problem that they fuse with the carrier and other members such as the electrocharging blade.
Also, the transparency of polyester is not sufficient and it cannot satisfactorily be applied to a full-color toner which requires a high transparency.
The purposes of the present invention are to solve the above-mentioned problems associated with conventional toners for electrophotography and provide a toner for electrophotography having a high fixing strength at a low temperature, which does not generate hazardous volatile gases. The toner for electrophotography of the present invention also has a good adaptability for full-color toners and is designed in consideration of the environmental influence.
SUMMARY OF THE INVENTION
Accordingly, the present invention relates to a toner for electrophotography including a polylactic acid type biodegradable resin and a terpene-phenol copolymer as a binder resin.
With regard to the polylactic acid type biodegradable resin, the molar concentration of one of L-lactic acid unit and D-lactic acid unit in a lactic acid component of the polylactic acid type biodegradable resin is in the range between about 75 mol % and about 98 mol %.
The terpene-phenol copolymer includes at least one composition selected from the group consisting of: (a) cyclic terpene-phenol copolymer, prepared by copolymerizing cyclic terpene and phenol; (b) cyclic terpene/phenol (1:2 molar ratio) addition product, prepared by adding two molecules of phenol to one molecule of cyclic terpene; (c) polycyclic terpene/phenol (1:2 molar ratio) addition product, prepared by a condensation reaction of a cyclic terpene/phenol (1:2 molar ratio) addition product with one of aldehydes and ketones; and (d) polycyclic terpene/phenol (1:1 molar ratio) addition product, prepared by a condensation reaction of a cyclic terpene/phenol (1:1 molar ratio) addition product with one of aldehydes and ketones.
The present invention also provides a toner for electrophotography, wherein the ratio of the polylactic acid type biodegradable resin with respect to the terpene-phenol copolymer is in the range between about 80:20 and about 20:80.
The present invention also provides a toner for electrophotography, wherein the melting start temperature of the toner is about 110° C. or lower.
The present invention also provides a full-color toner, including: a polylactic acid type biodegradable resin; and a terpene-phenol copolymer.
The present invention also provides a full-color toner, wherein the molar concentration of one of L-lactic acid unit and D-lactic acid unit in a lactic acid component of the polylactic acid type biodegradable resin is in the range between about 75 mol % and about 98 mol %.
The present invention also provides a full-color toner, wherein the terpene-phenol copolymer includes at least one composition selected from the group consisting of: (a) cyclic terpene-phenol copolymer, prepared by copolymerizing cyclic terpene and phenol; (b) cyclic terpene/phenol (1:2 molar ratio) addition product, prepared by adding two molecules of phenol to one molecule of cyclic terpene; (c) polycyclic terpene/phenol (1:2 molar ratio) addition product, prepared by a condensation reaction of a cyclic terpene/phenol (1:2 molar ratio) addition product with one of aldehydes and ketones; and (d) polycyclic terpene/phenol (1:1 molar ratio) addition product, prepared by a condensation reaction of a cyclic terpene/phenol (1:1 molar ratio) addition product with one of aldehydes and ketones.
The present invention also provides a full-color toner, wherein the ratio of the polylactic acid type biodegradable resin with respect to the terpene-phenol copolymer is in the range between about 80:20 and about 20:80.
The present invention also provides a full-color toner, wherein the melting start temperature of the toner is about 110° C. or lower.
The toner for electrophotography according to the present invention has an excellent fixing strength at low temperatures, anti-offset property, anti-filming property on a photosensitive member, and anti-fusing property on electrocharging members. Also, the transparency of the toner for electrophotography according to the present invention is applicable to a full-color toner. Moreover, in the process for preparing the toner for electrophotography of the present invention and in the fixing process using the toner of the present invention, hazardous gases such as styrene and xylene are not generated. Further, according to the present invention, the durability of the toner is increased and yet its fluidity, anti-fusing property and anti-spent property are not deteriorated. In addition, the toner for electrophotography according to the present invention has an excellent cost efficiency.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter the toner for electrophotography according to the present invention will be described in detail.
In the toner for electrophotography of the present invention, it is essential that the toner contains a polylactic acid type biodegradable resin and a terpene phenol copolymer.
The term “a polylactic acid type biodegradable resin” u
Horibe Yasumasa
Okuyama Hisashi
Suwa Yoshihito
Goodrow John
Nixon & Vanderhye P.C.
Tomoegawa Paper Co. Ltd.
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