JP3113431B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used for developing a latent image formed on an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric to visualize the latent image.

[0002]

2. Description of the Related Art Conventionally, a developing device for developing an electrostatic latent image formed on the surface of a photosensitive drum as an image carrier by using a magnetic toner of a one-component developer has been developed. Due to the friction between the developing sleeve as the agent carrier and the magnetic toner particles, an electrostatic image charge on the photosensitive drum and a charge having a polarity opposite to the developing reference potential are given to the magnetic toner particles, and the magnetic toner is extremely thinly applied on the developing sleeve. The photosensitive drum and the developing sleeve are applied and transported to a developing area where the developing sleeve is opposed, and the magnetic toner flies to an electrostatic latent image on the surface of the photosensitive drum by the action of a magnetic field of a magnet immovably installed in the developing sleeve in the developing area. There is known an image forming apparatus that adheres and develops an image to develop an electrostatic latent image as a toner image.

As the developing sleeve used in these methods, as disclosed in Japanese Patent Application Laid-Open No. 57-66433, aluminum, nickel, corrosion-resistant steel (stainless steel)
Such a metal, an alloy thereof, or a compound thereof is formed into a cylindrical shape, and the surface thereof is generally processed by electrolysis, blasting, sanding, or the like so as to have a predetermined surface roughness.

[0004] Such a developing sleeve is inexpensive and can form a high quality image relatively stably. On the other hand, in the case of using a toner of a one-component developer in which charging is performed by friction with the developing sleeve, it is difficult to adjust the toner charging, and although various measures have been taken with toner,
Problems relating to charging non-uniformity and long-term charging stability have not been completely solved.

In particular, the toner existing in the vicinity of the surface of the developing sleeve in the toner layer formed on the surface of the developing sleeve by the regulating member in the developing step has a very high charge, and is attracted to the surface of the developing sleeve more strongly by the mirror force. As a result, there is no chance of friction between the toner and the developing sleeve, so that the toner cannot have an appropriate charge.

Under such circumstances, sufficient development and transfer are not performed, resulting in an image having many density unevenness and scattering of characters.

[0007]

A method for reducing the amount of toner having too high a charge and providing a charge amount suitable for development is disclosed in JP-A-3-12676. In addition, a coating in which a conductive agent such as carbon or graphite is dispersed is provided on a metal substrate to form a developing sleeve, thereby charging the toner. There is a proposal intended to prevent the strong adhesion of the toner and to make the toner on the developing sleeve have a charge amount suitable for development.

[0008] However, this is not enough.
In the method disclosed in Japanese Patent Application Laid-Open No. Hei 3-12676 or the like, a difference in a developing device, a process condition, a type of a toner, etc.
The charge of the toner may show a low value, in which case a phenomenon such as a decrease in image density under high temperature and high humidity occurs.

Further, in a coating film containing carbon-graphite and spherical particles in a binder resin as disclosed in JP-A-3-200986, glass or silicone resin which gives a high charge to the toner as spherical particles,
Similarly, even when the PMMA resin and the nylon resin are used alone, a satisfactory charge may not be obtained.

[0010] An object of the present invention is to stably and appropriately impart a charge to a one-component developer carried thereon by a developer carrying member, and to develop a uniform, high-quality image free from density unevenness by development using the developer. Is to provide a developing device capable of obtaining the following.

Another object of the present invention is to provide a developing apparatus capable of obtaining a high-quality image free from density reduction, sleeve ghost, etc. not only at room temperature and normal humidity but also at low temperature and low humidity, and at high temperature and high humidity. To provide.

[0012]

The above object is achieved by a developing apparatus according to the present invention. In summary, the present invention forms a film containing a solid lubricant and a conductive agent on a binder resin on the surface of a developer carrier carrying a one-component developer for developing a latent image formed on the image carrier. In the developing device, the coating, in the binder resin, in addition to the solid lubricant and the conductive agent, further contains a plurality of types of particles having a chargeability opposite to the charge polarity of the developer. The content of a plurality of types of particles exhibiting chargeability opposite to the charge polarity of the developer,
10 to 100 parts by weight with respect to 100 parts by weight of the binder resin, the coating contains inorganic particles and resin particles as a plurality of types of particles exhibiting chargeability of the opposite polarity to the charge polarity of the developer, A developing device, wherein the content ratio by weight of the inorganic particles and the resin particles satisfies the following relationship: inorganic particles / resin particles = 1/10 to 10/1.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

In the present invention, it is important to form a film containing a binder resin containing a solid lubricant and a conductive agent and further containing a plurality of types of particles on the surface of a developer carrier, for example, a developing sleeve. It is a feature.

As the conductive agent, for example, aluminum,
Metal powders such as copper, nickel, and silver; short metal fibers; carbon fibers; conductive metal oxides such as antimony oxide, indium oxide, and tin oxide; and conductive powders such as carbon black and graphite. . Among them, graphite, particularly crystalline graphite, is suitably used because it has lubricity as well as conductivity and can reduce toner adhesion to the developer carrying member.

Crystalline graphite is roughly classified into natural graphite and artificial graphite. Artificial graphite was obtained by solidifying pitch coke with tar pitch or the like, firing once at about 1200 ° C., and then putting it into a graphitization furnace and treating it at a high temperature of about 2300 ° C., whereby carbon crystals grew into graphite. Things. Natural graphite is completely graphitized by geothermal heat and underground high pressure for a long time, and is produced from underground. These graphites have various excellent properties, and have wide industrial applications. Graphite is a dark gray or black glossy, very soft, lubricious carbon crystal that is used for pencils and other materials, and has heat resistance and chemical stability. It is used in powder, solid, and paint forms. The crystal structure is classified into a hexagonal system and a rhombohedral system, and has a complete layer structure. Regarding electrical properties, free electrons exist between carbon and carbon bonds, and are good conductors of electricity. In the present invention, either natural or artificial graphite can be used. The particle size of the graphite used is preferably about 0.5 μm to 20 μm.

As the carbon fine particles, conductive amorphous carbon can be used. The conductive amorphous carbon is generally defined as "an aggregate of crystallites formed by burning or thermally decomposing a compound containing hydrocarbons or carbon in an insufficient air supply". In particular, it is excellent in electric conductivity, and is widely used because it can be filled with a polymer material to impart conductivity, or a certain degree of conductivity can be obtained by controlling the amount of addition. The particle diameter of the conductive amorphous carbon used in the present invention is preferably from 10 mμm to 80 mμm,
Those having m to 40 mμm are more preferable.

Examples of the binder resin include thermoplastic resins such as styrene resin, vinyl resin, polyether sulfone resin, polycarbonate resin, polyphenylene oxide resin, polyamide resin, fluorine resin, cellulose resin, and acrylic resin; Epoxy resin, polyester resin, alkyd resin, phenol resin, melamine resin,
A thermosetting resin such as a polyurethane resin, a urea resin, a silicone resin, and a polyimide resin; or a photocurable resin can be used. Among them, those having release properties such as silicone resin and fluororesin, or mechanical properties such as polyether sulfone resin, polycarbonate resin, polyphenylene oxide resin, polyamide resin, phenol resin, polyester resin, polyurethane resin and styrene resin More excellent is more preferable.

In the present invention, as described above, the coating formed on the surface of the developing sleeve further contains plural kinds of particles in addition to the solid lubricant and the conductive agent in the binder resin. The plurality of types of particles have a property of exhibiting chargeability opposite to the charge polarity of the toner which is a one-component developer, and particles having positive chargeability are used for negatively chargeable toner. Is done.

The particles exhibiting positive chargeability include glass such as quartz glass, borosilicate glass and soda glass, or silicate compounds such as asbestos, silicone resin (including silicone rubber as described later), PMMA resin, and nylon. And a resin such as a resin. Particularly, a combination of an inorganic substance and a resin is used. The number average particle size of these particles is preferably about 0.05 to 30 μm.

Specific examples thereof include, for example, quartz glass and silicone rubber, borosilicate glass and silicone rubber,
Soda glass and silicone rubber, quartz glass and PMMA
There are combinations of resin, soda glass and PMMA resin, quartz glass and nylon resin, borosilicate glass and nylon resin, and soda glass and nylon resin. However, the types of these particles are not limited to two.

In the present invention, the reason why the binder resin further contains a plurality of types of particles in addition to the solid lubricant and the conductive agent is as follows.
This is for appropriately increasing the charge of the toner on the developing sleeve. The content of the plurality of types of particles is in the range of 10 to 100% by weight based on the binder resin. If the content is less than 10% by weight, the charge of the toner cannot be increased appropriately. If the content is more than 100% by weight, the mechanical strength of the film formed on the developing sleeve deteriorates. The compounding ratio of the plural kinds of particles is 1/10 to 10/1 in terms of the weight ratio of inorganic substance / resin, and if it is out of this range, the charge of the toner cannot be appropriately increased.

Next, a developing device in which the developing sleeve of the present invention is incorporated will be described. FIG. 1 is a schematic configuration diagram showing an embodiment of the developing device of the present invention.

As shown in FIG. 1, the present developing apparatus includes a developing container 1, a sleeve-shaped developing sleeve 2 rotatably installed in the developing container 1, and a magnet immovably installed in the developing sleeve 2. 3 and a toner regulating blade 4 provided above the top of the developing sleeve 2.

With the above configuration, the developing sleeve 2 rotates in the direction of arrow a to form an electrostatic latent image that rotates the magnetic toner 5 as a one-component magnetic developer in the developing container 1 in the direction of arrow b. The developing position facing the photosensitive drum 6 (the developing sleeve 2)
And the photosensitive drum 6 at a position closest to the photosensitive drum 6).
The electrostatic latent image on the photosensitive drum 6 is developed with the toner 5 at the developing position G, and is visualized as a toner image.

At this time, the toner 5 carried on the developing sleeve 2 is regulated to a predetermined thickness by the toner layer thickness regulating blade 4 and is conveyed to the developing position G. An alternating electric field is applied to the developing sleeve 2 as a developing bias by a bias power supply 7. The remaining toner that has performed the developing operation at the developing position G is transferred to the developing container 1 by the rotation of the developing sleeve 2.
And is collected from above the developing sleeve 2.

Hereinafter, specific examples of the present invention will be described.

Example 1 A coating film was formed on a developing sleeve substrate using a coating solution having the following composition to prepare a developing sleeve according to the present invention.

Phenol resin 100 parts Crystalline graphite 70 parts Carbon black 30 parts Silicone rubber particles (number average particle diameter 5 μm) 25 parts Quartz glass particles (number average particle diameter 10 μm) 25 parts Methanol 100 parts Isopropyl alcohol 300 parts

The above coating material mixture was dispersed at room temperature for 5 hours using a sand mill. After diluting the obtained dispersion with isopropyl alcohol to a solid content of 20% by weight to form a coating liquid, the coating liquid was applied to an aluminum developing sleeve substrate having a diameter of 20 mm to a thickness of 7 μm by a spray method, Next, the film was heated in a hot air drying oven at 150 ° C. for 30 minutes and cured to form a film, thereby forming a developing sleeve according to the present invention.

Next, this developing sleeve was used in the developing device shown in FIG. 1 and incorporated in a modified copy machine of Canon NP20202 which was made into a digital copy machine to carry out a copy experiment. The charge, image density and sleeve ghost were evaluated. The environment of the copying experiment was 24 ° C., 65% RH, normal temperature and normal humidity (N / N), 10
℃, 10% RH low temperature and low humidity (L / L), and 30 ℃, 8
The test was performed in a high temperature and high humidity environment of 0% RH.

As the developer, the following raw material magnetic toner was used.

Styrene-acrylic resin 100 parts Magnetite 50 parts Negative charge control agent 2 parts Low molecular weight polypropylene 3 parts

The above raw material mixture is kneaded, crushed and classified by a conventional method, and has a weight average particle size of 8.6 μm and a particle size of 4.0.
A pulverized magnetic toner in which the number% of μm or less was 10% was obtained and used.

Table 1 shows the obtained results. In Table 1, the evaluation of the image is ◎: excellent, ：: good, Δ: practically acceptable, ×: practically impossible. The image density depends on the Macbeth reflection density: ◎: 1.4 or more, ：: 1.2 to 1.4, Δ:
1.0 to 1.2, x: 1.0 or less. Sleeve ghosts are visual.

Comparative Example 1 A coating liquid was prepared in the same manner as in Example 1 except that the silicone rubber particles and the quartz glass particles were not blended. Other than that, it carried out similarly to Example 1, formed the coating film, produced the developing sleeve, and evaluated. The results are shown in Table 1 above.

Comparative Example 2 Example 1 was repeated except that 25 parts of silicone rubber particles were used in place of 25 parts of quartz glass particles (total of 50 parts of silicone rubber particles) to prepare a coating solution. A developing sleeve was formed and evaluated in the same manner as described above. Table 1 also shows the results.

Comparative Example 3 Example 1 was repeated except that 25 parts of silica glass particles were used instead of 25 parts of silicone rubber particles (total of 50 parts of quartz glass particles) to prepare a coating solution. A developing sleeve was formed and evaluated in the same manner as described above. Table 1 also shows the results.

[0039]

[Table 1]

In Example 1, in addition to graphite and carbon black, the binder resin further contained quartz glass particles and silicone rubber particles as a plurality of types of particles having positive chargeability to form a coating on the surface of the developing sleeve. So
As shown in Table 1, the toner on the developing sleeve is stable and appropriate not only at normal temperature and normal humidity (N / N) but also at low temperature and low humidity (L / L) and high temperature and high humidity (H / H). Was obtained, and as a result, a high-quality image having a high density, uniformity and no sleeve ghost could be obtained.

On the other hand, in Comparative Examples 1 to 3, the coating film was formed without containing one or both of quartz glass particles and silicone rubber particles in the binder resin. Has a relatively low charge amount,
Particularly, in a high-temperature, high-humidity environment, the image density was practically acceptable or practically unacceptably low.

Example 2 In Example 1, instead of 25 parts of quartz glass particles and 25 parts of silicone rubber particles as particles exhibiting positive chargeability,
17 parts of soda glass particles (number average particle diameter 10 μm),
A coating liquid was prepared using 17 parts of PMMA resin and 17 parts of nylon resin. Otherwise, a coating was formed in the same manner as in Example 1, and a developing sleeve was prepared and evaluated.

Table 2 shows the results. In Table 2, symbols for image evaluation are the same as in Table 1.

Comparative Example 4 A coating liquid was prepared in the same manner as in Example 1 except that 50 parts of soda glass particles (number average particle diameter: 10 μm) were used instead of 25 parts of quartz glass particles and 25 parts of silicone rubber particles. A coating was formed in the same manner as in Example 1, and a developing sleeve was prepared and evaluated. The results are shown in Table 2 above.

Comparative Example 5 A coating liquid was prepared in the same manner as in Example 1 except that 50 parts of PMMA resin particles (number average particle diameter: 10 μm) were used instead of 25 parts of quartz glass particles and 25 parts of silicone rubber particles. A coating was formed in the same manner as in Example 1, and a developing sleeve was prepared and evaluated. Table 2 also shows the results.

Comparative Example 6 A coating liquid was prepared in the same manner as in Example 1, except that 50 parts of nylon resin particles (number average particle diameter: 10 μm) were used instead of 25 parts of quartz glass particles and 25 parts of silicone rubber particles. A coating was formed in the same manner as in Example 1, and a developing sleeve was prepared and evaluated. Table 2 also shows the results.

[0047]

[Table 2]

In Example 2, in addition to graphite and carbon black, soda glass particles, PMMA resin particles, and nylon resin particles as a plurality of positively chargeable particles were further added to the binder resin to form a surface of the developing sleeve. As shown in Table 2, the coating film was formed on the developing sleeve not only at room temperature and normal humidity (N / N) but also at low temperature and low humidity (L / L) and high temperature and high humidity (H / H). The toner can be charged stably and appropriately, and a high-quality image having a high density and having no sleeve ghost can be obtained.

On the other hand, in Comparative Examples 4 to 6, since the binder resin contained only one of soda glass particles, PMMA resin particles, or nylon resin particles to form a coating, all of them were formed on the developing sleeve. The charge amount of the toner was relatively low, and the result was that the density of the image was practically as low as possible especially in a high temperature and high humidity environment.

[0050]

As described above, according to the present invention, the solid lubricant and the binder resin are provided on the surface of the developer carrier for carrying the one-component developer for developing the latent image formed on the image carrier. In the developing device in which the coating containing the conductive agent is formed, the coating further includes, in the binder resin, a plurality of types of particles having a chargeability opposite to the charge polarity of the developer, in addition to the solid lubricant and the conductive agent. Contains, the content of a plurality of types of particles exhibiting chargeability of the opposite polarity to the charge polarity of the developer is 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin, the coating is the developer Inorganic particles and resin particles are contained as a plurality of types of particles exhibiting chargeability of the opposite polarity to the charge polarity, and the content ratio by weight of the inorganic particles and the resin particles is as follows: inorganic particles / resin particles = 1/10 to 10/1 Is satisfied, that is, (a) Since a coating containing a solid lubricant and a conductive agent in a binder resin is formed on the surface of the developer carrier that carries the component developer, the toner is charged by frictional charging with the film on the surface of the developer carrier. At the same time, the generation of highly charged toner and the strong adhesion of the toner to the surface of the developer carrying member due to the mirror image are prevented; (b) the coating forms the solid lubricant and the conductive material in the binder resin. In addition to the developer, since a specific amount of a plurality of types of particles having a chargeability opposite to the charge polarity of the developer is further contained, the mechanical strength of the film formed on the surface of the developer carrier is reduced. (C) the coating is composed of inorganic particles and resin as a plurality of types of particles exhibiting chargeability of the opposite polarity to the charge polarity of the developer. Said inorganic particles containing particles Since the weight ratio of the particles to the resin particles satisfies the specific relationship, it is possible to appropriately increase the charge of the toner; therefore, the present invention provides a combination of the above (a) to (c). Under normal temperature and normal humidity, low temperature and low humidity, and high temperature and high humidity environments, in addition to normal temperature and normal humidity, even under low temperature and low humidity, under high temperature and high humidity, the developer carried on the developer carrying member By applying a charge stably and appropriately, a high-quality image free from density reduction and density unevenness can be obtained by development using the charge.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a developing device of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 developing container 2 developing sleeve 3 fixed magnet 4 toner regulating member 5 magnetic toner 6 photosensitive drum 7 bias power supply

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Umino 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Michiko Orihara 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-3-200986 (JP, A) JP-A-63-123071 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/08 -13/095 G03G 15/08-15/095

Claims (1)

(57) [Claims] 1. A developing method in which a coating containing a solid lubricant and a conductive agent in a binder resin is formed on the surface of a developer carrying member carrying a one-component developer for developing a latent image formed on the image carrying member. In the apparatus, the coating further contains, in addition to the solid lubricant and the conductive agent, a plurality of types of particles having a chargeability opposite to the charge polarity of the developer, in the binder resin, The content of a plurality of types of particles exhibiting chargeability of the opposite polarity to the charge polarity of the developer is 10 wt.
To 100 parts by weight, wherein the coating contains inorganic particles and resin particles as a plurality of types of particles exhibiting chargeability of the opposite polarity to the charge polarity of the developer, and the content weight ratio of the inorganic particles and the resin particles Satisfies the following relationship: inorganic particles / resin particles = 1/10 to 10/1.