Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-07-26
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...
C430S108800, C430S109300
Reexamination Certificate
active
06756170
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrostatic image developing toner to be used for developing electrostatic images in an electrophotographic copying machines, laser beam printers and electrostatic recording apparatuses wherein an image is formed utilizing an electrophotographic method or an electrostatic recording method, and a method for forming an image using the electrostatic image developing toner.
2. Description of the Related Art
In copying machines for copying an original, printers for recording output of a computer including a personal computer, or printers for facsimile receiving apparatuses, an electrophotographic method or an electrostatic recording method has long been popularly employed for obtaining a copied or recorded image. Typical examples of the copying machine or printer employing this electrophotographic method or the electrostatic recording method include an electrophotographic copying machine, a laser beam printer, a printer using a liquid crystal array and an electrostatic printer. In the electrophotographic method or the electrostatic recording method, an electrostatic latent image (electrostatic charge image) is formed on an electrostatic image carrier such as an electrophotographic photoreceptor or an electrostatic recording medium through various means, and is developed with a developer. The resultant toner image is transferred, if necessary, to a transfer medium such as paper, then fixed by heating, applying pressure, applying heat and pressure or with a solvent vapor to thereby obtain a final toner image. On the other hand, toner particles not transferred and remaining on the electrostatic image carrier are removed by a cleaning means. By repeating the above-described steps, copied products or recorded products can be obtained in sequence.
As a method for developing the electrostatic image, there have been known a method of using a liquid developer comprising a fine toner dispersed in an electrically insulating liquid; a method of using a powdery toner comprising a colorant and, if necessary, a magnetic substance dispersed in a binder resin together with a particulate carrier; and a method of conducting development using a magnetic toner comprising a magnetic substance dispersed in a binder resin and not using a particulate carrier. Of these methods, dry developing methods using a powdery toner or a magnetic toner have been mainly employed in recent years.
Incidentally, speeding up of electrophotographic copying machines and laser beam printers have recently been required with the progress of reduction in size and personalization and, in addition, it has also been required to reduce necessary energy. Therefore, with these apparatus, various improvements have been attempted to obtain a highly reliable and high-quality image at a high speed with a low energy for a long period of time through a mechanism as simple as possible. Also, in company with such improvements of the apparatus, various improvements have been attempted with respect to toners to be used for development.
For example, as an apparatus for fixing a toner image, there have been widely employed a hot-pressing fixing apparatus using a heating roller and a hot-pressing fixing apparatus wherein a roll-like or continuous heat-resistant film, so-called fixing belt, through which a heating member and the developing surface of a transfer member such as paper is faced each other, and heating is conducted by the heating member, the fixing belt and the transfer member are conveyed in this integrated state while pressing the transfer member from back side thereof using a press roller to thereby conduct hot-pressing fixation. In these methods, the heating roller or the fixing belt directly contacts with a toner image upon fixing of the toner image, and hence conduction of heat to the toner can be realized with such a good efficiency that the toner can be smoothly molten with a low energy at a high speed. In these methods, however, the molten toner comes into direct contact with the heating roller or the fixing belt. Therefore there is involved a problem of staining a transfer member such as paper due to so-called offset phenomenon. That is, a part of the molten toner on a transfer member transfers to and deposits on the surface of the heating roller or the fixing belt, and when the heating roller or the fixing belt again contacts with the transfer member, the toner having transferred and deposited on the heating roller or the like transfers again to the transfer member or, in the case where there exists no transfer member, the toner having transferred to and deposited on the heating roller or the like transfers to a pressing roll and, when a next transfer member passes through the fixing apparatus, it deposits on the back side of the transfer member.
On the other hand, in view of fixing the toner at a low temperature, it is effective to reduce a softening temperature (Tm) of a toner binder resin. However, reduction of Tm generally causes reduction of the glass transition temperature (Tg) of the toner, thus it is known that so-called toner blocking of forming a block of toner during storage or the offset phenomenon of toner upon fixing is liable to take place. This is one of the causes that inhibit to reduce the fixing temperature as one desires. As a technique for simultaneously obtaining the low-temperature fixability and blocking resistance or offset resistance, there has been proposed a technique of using a polyester-based resin which shows a comparatively low fixing temperature even when Tm or Tg is high (Japanese Unexamined Patent Publication No. 1952/1981). However, this technique fails to satisfy simultaneously and sufficiently requirements for low-temperature fixability, blocking resistance and offset resistance.
As another technique, there has been proposed to use a resin composed of a lower molecular component and a higher molecular component. For example, Japanese Unexamined Patent Publication No. 16144/1981 describes to use a styrene-based copolymer mixture showing a chromatogram obtained by gel permeation chromatography (GPC) wherein at least one maximum value of the molecular weight exist in each of a molecular weight region of from 10
3
to 8×10
4
and a molecular weight region of from 10
5
to 2×10
6
; Japanese Unexamined Patent Publication No. 229158/1987 describes to use a polyester having 5 to 25% by weight of chloroform-insoluble component; Japanese Unexamined Patent Publication No. 168264/1990 describes to use a carboxylic acid group-containing vinyl polymer having a weight-average molecular weight of 1×10
3
to 2×10
4
and a ratio of weight-average molecular weight
umber-average molecular weight of 3 or less and a carboxylic acid group-containing vinyl polymer having a weight-average molecular weight of 1.5×10
5
to 8×10
5
and a ratio of weight-average molecular weight
umber-average molecular weight of 1.5 or more; Japanese Unexamined Patent Publication No. 294867/1991 describes to use a styrene-acrylic-based copolymer having a molecular weight distribution showing a gel permeation chromatogram wherein a maximum value of the molecular weight exists in each of a molecular weight region of 1×10
5
or more and a molecular weight region of from 500 to 2×10
4
, and wherein a minimum value of the molecular weight exists between the two maximum values, and a ratio of the sum of the areas of two peaks respectively containing the two maximum values to the area of the valley under a tangential line common to the two peaks and containing the minimum value is 0.30 or less; and Japanese Unexamined Patent Publication No. 297629/1993 describes to use a binder resin which has a molecular weight distribution measured by GPC wherein at least one peak exists in a molecular weight region of from 3×10
3
to 5×10
4
and at least one peak in a molecular weight region of 10
5
or more, which contains 50% or more components of 10
5
or less in molecular weight, and which shows sp
Hikosaka Takaaki
Iemura Hirofumi
Nakanishi Yasushi
Goodrow John L
McDermott & Will & Emery
Toyo Ink Manufacturing Co. Ltd.
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