Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2001-11-05
2003-12-30
Chapman, Mark A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S109300, C430S111400, C430S111410
Reexamination Certificate
active
06670087
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a toner used in recording processes such as electrophotography, electrostatic recording, magnetic recording and toner jet recording, and an image-forming apparatus, a process cartridge and an image-forming method which make use of the toner; the image-forming method being a method of forming a fixed image by heat and pressure fixing a toner image formed on a transfer medium.
2. Related Background Art
A number of methods as disclosed in U.S. Pat. No. 2,297,691, Japanese Patent Publications No. 42-23910 and No. 43-24748 and so forth are conventionally known as methods for electrophotography. In general, copies are obtained by forming an electric latent image (electrostatic latent image) on a photosensitive member by various means utilizing a photoconductive material, subsequently developing the latent image by the use of a toner to form a toner image, and transferring the toner image to a transfer medium (recording medium) such as paper as occasion calls, followed by fixing by the action of heat, pressure, heat-and-pressure, or solvent vapor. The toner that has not transferred and has remained on the photosensitive member is cleaned by various means, and then the above process is repeated.
In recent years, as a reflection of changing commercial needs for making composite, personal and so forth, such copying machines are severely sought to be made more small-sized, more light-weight, more high-speed and more highly reliable. As the result, performances required for toners have also become high-level.
In particular, one-component development making use of magnetic toners is preferably used because of its developing assembly having a simple structure, which may cause less troubles, has a long lifetime and may require only easy maintenance service.
Still in recent years, image-forming apparatus employing an electrophotographic technique, such as copying machines and laser beam printers, have been made to have various functions, and toner images to be formed are sought to be of high precision and high image quality. Accordingly, used are toners suited therefor and process cartridges making use of such toners.
For example, Japanese Patent Publication No. 51-23354 discloses a toner comprising a vinyl polymer cross-linked to an appropriate degree by adding a cross-linking agent and a molecular weight modifier. Also proposed in a large number are toners of a blend type comprising a vinyl polymer in which its Tg, molecular weight and gel content are specified in combination.
Such toners containing a cross-linked vinyl polymer or a gel content have an excellent effect on anti-offset properties. However, where such a cross-linked vinyl polymer is used in order to incorporate it in a toner, the polymer may have a very great internal friction in the step of melt kneading when the toner is produced, and a large shear force is applied to the polymer. Hence, in many cases, the cutting of molecular chains occurs to cause a decrease in melt viscosity, and this may adversely affect the anti-offset properties.
Accordingly, to solve this problem, it is proposed, as disclosed in Japanese Patent Applications Laid-open No. 55-90509, No. 57-178249, No., 57-178250 and No. 60-4946, that, a resin having a carboxylic acid and a metal compound are used as toner materials and are heated and reacted at the time of melt kneading to form a cross-linked polymer, which is then incorporated into the toner.
Japanese Patent Applications Laid-open No. 61-110155 and No. 61-110156 also disclose that a binder having as essential constituent units a vinyl resin monomer and also a special monoester compound is allowed to react with a polyvalent metal compound to carry out cross-linking through a metal.
Japanese Patent Applications Laid-open No. 63-214760, No. 63-217362, No. 63-217363 and No. 63-217364 still also disclose that a binder resin has a molecular weight distribution separated into two groups, a low-molecular weight region and a high-molecular weight region, and carboxylic acid groups incorporated into the low-molecular weight region side are allowed to react with polyvalent metal ions to carry out cross-linking (a dispersion of a metal compound is added in a solution obtained by solution polymerization, followed by heating to carry out the reaction).
Japanese Patent Applications Laid-open No. 2-168264, No. 2-235069, No. 5-173363, No. 5-173366 and No. 5-241371 still also disclose toner binder compositions and toners in which the molecular weights, mixing ratio, acid values and their percentages of a low-molecular weight component and a high-molecular weight component in a binder resin are controlled to improve fixing performance and anti-offset properties.
Japanese Patent Application Laid-open No. 62-9256 still also discloses a toner binder composition comprising a blend of two kinds of vinyl resins having different molecular weights and acid values of resin.
Japanese Patent Applications Laid-open No. 3-63661, No. 3-63662, No. 3-63663 and No. 3-18552 still also disclose that a carboxyl-group-containing vinyl copolymer and an epoxy-group-containing vinyl copolymer are allowed to react with a metal compound to carry out cross-linking.
Japanese Patent Applications Laid-open No. 7-225491 and No. 8-44107 still also disclose that a carboxyl-group-containing resin reacts with an epoxy resin to form a cross-linked structure.
Japanese Patent Applications Laid-open No. 62-194260, No. 6-11890, No. 6-222612, No. 7-20654, No. 9-185182, No. 9-244295, No. 9-319410, No. 10-87837 and No. 10-90943 still also disclose toner binder compositions and toners in which molecular weight distribution, gel content, acid value and epoxy value are controlled in a resin composition constituted of a carboxyl-group-containing resin, using a glycidyl-group-containing resin as a cross-linking agent, to improve fixing performance and anti-offset properties.
These proposals disclosed as shown above, though having merits and demerits, have in fact attained good effects with respect to the improvement in anti-offset properties. There, however, are problems in developing performance and running performance when applied to magnetic toners for one-component development. Thus, a further improvement is required.
Japanese Patent Applications Laid-open No. 1-257968, No. 4-124681 and No. 6-51556 also disclose magnetic toners whose dielectric dissipation factor has been controlled to provide toners having good chargeability.
In the above proposal, however, there is a problem when applied in high-speed machines having a large copy volume, and a further improvement is required in order to improve the dispersibility of resins and magnetic materials.
As stated in the above proposals, the quality of image formation depends greatly on charging performance of magnetic toners. In the magnetic toners, a magnetic material is incorporated into a toner to endow the toner with magnetic properties. Also, part of the magnetic material stands liberated from toner particles or uncovered to their surfaces, and hence it influences the fluidity of magnetic toner and the triboelectric chargeability with a charging member in a developing assembly to influence developing performance and running performance. In particular, in recent years, a high running performance is required as a performance of the magnetic toner, and hence it is difficult to achieve both the properties of a resin and the dispersibility of a magnetic material which are used in toner particles. Especially when a cross-linked type resin is used, a further improvement is required for resin materials and magnetic materials.
Many proposals have been made on the magnetic materials. For example, a magnetic material incorporated with silicon and zinc is proposed in Japanese Patent Application Laid-open No. 8-101529; magnetic materials incorporated with silicon are proposed in Japanese Patent Applications Laid-open No. 7-175262, No. 5-72801, No. 62-278131, No. 61-34070, No. 8-25747, No. 9-59024 and No. 9-59025; magnetic materials incorporated wi
Fujikawa Hiroyuki
Fujimoto Masami
Kobori Takakuni
Taya Masaaki
Canon Kabushiki Kaisha
Chapman Mark A.
Fitzpatrick ,Cella, Harper & Scinto
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