Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
1999-10-05
2001-02-20
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...
C430S107100
Reexamination Certificate
active
06190816
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a toner resin composition and toner used in electrophotography and such, and more particularly to a toner resin composition and toner used in the so-called dry developing method for developing electrostatic charge images.
2. The Prior Art
The dry developing method is widely used to develop electrostatic charge images in electrophotography. In the dry developing method, toner is usually electrified by means of friction with iron powder, glass beads, etc., which are called carriers, and then attached to electrostatic latent images on the photosensitive matter due to electrical attraction, transferred to the paper sheet, and then fixed by heating rollers and such to form permanent visible images.
For the fixing process, the heating roller method is widely used in which the toner images on said sheet are pressed onto the surface of the heating roller, which has a toner-separating material formed on its surface, as the sheet goes through.
In the heating roller method, a toner resin composition which can be fixed at a lower temperature is desirable so as to improve cost efficiency, including power consumption, and increase the copying speed.
Toner resins which contain low molecular weight or low viscosity ethylene-type wax for improved fixability and anti-offset properties have been disclosed (Japanese unexamined patent publication Tokkai Hei 7-36218 and Tokkai Hei 8-114942).
However, they have a problem in that the shelf stability is poor due to the use of the ethylene-type wax.
Regarding shelf stability, it is known that the dispersibility of the low-melting-point crystalline compound present in the toner significantly affects the toner performance. Many patent applications have already been filed pertaining to the dispersion of the separability agent in toner (Tokkai Hei 9-211889, Tokkai Hei 2-27363, Tokkai Hei 3-296067, Tokkai Hei 4-69664, Tokkai Hei 9-288370, Tokkai Hei 9-288371, Tokkai Hei 9-288372, etc.). However, these methods only control the melt-kneading conditions at the time of making toner and their effect on dispersing the separability agent is not sufficient.
That is, when a toner resin composition with a low-melting-point crystalline compound whose dispersion is not controlled is tonerized under certain kneading conditions, the dispersion becomes somewhat finer, but there is a problem in that the distribution of dispersion particle size is wide, making it impossible to obtain toner with a homogeneous dispersion particle size. Tokkai Hei 6-175396 discloses a method to control the dispersion by grafting styrene-type monomers to polyethylene wax to control the dispersion; however, the degree of crystallization of the polyethylene wax was reduced due to the grafting and the shelf stability became poor, and therefore the basic performance of the toner was not satisfactory.
The present invention solves the aforementioned problem and its object is to provide a toner resin composition with superior fixability, anti-offset properties and shelf stability, as well as a toner which uses said toner resin composition.
BRIEF SUMMARY OF THE INVENTION
The toner resin composition of the present invention is a toner resin composition composed of a vinyl-type copolymer which has styrene-type monomers and (meth)acrylic ester-type monomers as the main ingredients, a low-melting-point crystalline compound, and a block compolymer of polystyrene and polyolefin wherein said vinyl-type copolymer has at least one peak value in both the range of 5,000-20,000 and the range of 500,000 or higher in the molecular weight distribution curve measured by gel permeation chromatography, the amount of said low-melting-point crystalline compound is 2-10 weight parts for 100 weight parts of said vinyl-type copolymer, the amount of said block copolymer is 0.5-5 weight parts for 100 weight parts of said vinyl-type copolymer, which toner resin composition having the characteristics that the average particle area is 0.5-20 &mgr;m
2
and the maximum particle area is 30 &mgr;m
2
or less in any 25 &mgr;m×25 &mgr;m area when transmission electron microscopyl is used to observe said low-melting-point crystalline compound which forms domains in the domain-matrix structure formed by said vinyl-type copolymer and the low-melting-point crystalline compound.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described below.
The toner resin composition of the present invention is composed of a vinyl-type copolymer which has styrene-type monomers and acrylic ester-type monomers as the main ingredients, a low-melting-point crystalline compound, and a block copolymer of polystyrene and polyolefin.
Examples of the aforementioned styrene-type monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, &agr;-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-t-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene and 3,4-dichlorostyrene.
Examples of the aforementioned (meth)acrylic ester monomers include (meth)acrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, and stearyl methacrylate; and also 2-chloroethyl acrylate, phenyl acrylate, methyl &agr;-chloro arylate, phenyl methacrylate, dimethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, bisglycidyl methacrylate, polyethyleneglycol dimethacrylate and methacryloxyethyl phosphate.
Of these, more preferably used are ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate and butyl methacrylate.
Other vinyl-type monomers can be added to the aforementioned vinyl-type copolymer.
Examples of the other vinyl type monomers include acrylic acid and its &agr;- or &bgr;-alkyl derivatives such as acrylic acid, methacrylic acid, &agr;-ethyl acrylic acid and crotonic acid; unsaturated dicarboxylic acids as well as their monoester derivatives and diester derivatives such as fumaric acid, maleic acid, citraconic acid and itaconic acid; and also monoacryloyloxyethyl succinate, monomethacryloyloxyethyl succinate, acrylonitrile, methacrylonitrile and acrylamide. They can be used either separately or in combinations of two or more.
For the aforementioned vinyl-type copolymer, those which have at least one peak value in both the range of 5,000-20,000 and the range of 500,000 or higher in the molecular weight distribution curve measured by gel permeation chromatography are used.
If the aforementioned peak value is in the molecular weight range lower than 5,000, then the strength of the toner resin composition decreases. If the peak value exists only in the molecular weight range higher than 20,000 and not in the molecular weight range 20,000 or lower, then there are adverse effects on the fixability.
Also, if the peak value exists only in the molecular weight range lower than 50,000 and not in the molecular weight range 50,000 or higher, then there are adverse effects on the anti-offset properties.
The peak values in the molecular weight distribution curve of the aforementioned vinyl-type copolymer are calculated by with a computer, for example, using the molecular weight distribution curve obtained by GPC. This GPC is usually measured by using HTR-C from Nihon Millipore Limited for the apparatus and one KF-800P, two KF-806Ms and one KF-802 serially connected for the columns.
For the measurement conditions, the temperature is 40° C., the sample concentration is 0.2 wt % in a THF solution (passed through a 0.45 &mgr;m filter), and the injected amount is 100 &mgr;l. Standard polystyrene is used for the calibration sample.
When polymerizing the aforementioned vinyl-type copolymer it is preferable to use an aliphatic hyd
Okudo Masazumi
Takehara Hiroaki
Ueyama Takashi
Goodrow John
Sekisui Chemical Co. Ltd.
Townsend & Banta
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