JP2835964B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used in the field of a technique for developing an electrostatic latent image with a developer, and particularly, the developer is carried on a surface of a developer carrying member. And a developing device for performing development.

2. Description of the Related Art Conventionally, for example, a developing device that visualizes a latent image formed on the surface of a photosensitive drum as an electrostatic latent image carrier with a magnetic toner as a one-component developer has been developed. Due to friction and friction between the sleeve as a developer carrier and the magnetic toner particles, a charge having a polarity opposite to the electrostatic image charge formed on the photosensitive drum is applied to the magnetic toner particles, and the magnetic toner is applied very thinly on the sleeve. Then, the toner is conveyed to a developing area formed by the photosensitive drum and the sleeve, and in the developing area, the magnetic toner flies under the action of a magnetic field from a magnet fixed in the sleeve to visualize the electrostatic latent image on the photosensitive drum. Things are known.

[Problems to be Solved by the Invention] However, in each of the developing devices as described above, a relatively thin uniform toner layer must be formed on the sleeve. However, environmental conditions, toner physical properties, and surface conditions of the sleeve are required. In some cases, a uniform toner layer cannot be obtained, and unevenness often occurs, particularly in a low humidity environment.

In addition, as the developer is repeatedly rubbed with the sleeve as the copying is repeated, additives for improving the fluidity of the toner and non-developing substances such as carriers in the two-component toner are deposited on the sleeve. The surface condition of the sleeve changes because the binder resin in the developer forms a film on the sleeve, so that the developability of the developer becomes unstable or the developer is not transported to the electrostatic latent image surface. There was a problem of stabilization.

Also, if fine powder is present in the toner, the fine powder toner selectively accumulates near the surface of the sleeve due to the difference in developability, and the original toner forms a layer on it. This makes it difficult to obtain a sufficient amount, and there is a problem that a so-called sleeve memory occurs, in which a difference in shading occurs between the fine powder layer forming portion and the normal portion.

In order to prevent such a change in the surface state of the sleeve, for example, a film containing an inorganic high-molecular carbon fluoride is formed (JP-A-57-66443). (Japanese Patent Application Laid-Open No. 58-178380), an organic silicone polymer, an aliphatic fluorine-containing compound, or at least one substance selected from styrene resins and polyferralene oxides, and a 2- to 6-dentate ligand Forming a film containing a metal complex having
8), etc., in which a material having a particularly high releasability is coated on the sleeve surface to prevent a change in the surface state has been proposed. However, these proposals did not solve the conventional problems such as the sleeve memory described above.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a developing device capable of uniformly carrying toner on a sleeve surface.

[Means and Actions for Solving the Problems] The present invention provides a developer accommodating chamber for accommodating a developer; and a developer accommodating in the developer accommodating chamber, the developer being carried on the surface. A developer carrier for carrying out the process, wherein the developer carrier carries the developer carried on a surface thereof;
The developer carrier is to be transported to a developing area formed between the surface of the electrostatic latent image carrier and the surface of the developer carrier, and the developer carrier has a surface for carrying and transporting the developer. Is formed of a film containing at least a film-forming polymer material and molybdenum disulfide.

In the present invention, the coating, molybdenum disulfide,
It is characterized in that it is formed so as to be exposed on the surface of the coating.

In the present invention, the molybdenum disulfide has an average particle diameter of 0.5 μm to 10 μm.

In the present invention, the coating has a volume resistivity of 10 ⁴ Ω
m or less.

In the present invention, the coating further contains a conductive material, and the content of the conductive material with respect to molybdenum disulfide is 40% by weight or less.

In the present invention, the conductive material is carbon black.

In the present invention, the coating contains a resin as a coating-forming polymer material, molybdenum disulfide and conductive amorphous carbon, and the total content of molybdenum disulfide and the content of conductive amorphous carbon (P) And the weight ratio of the resin to the resin content (B) satisfies the following relationship: P: B = 40: 10 to 5:10.

When the developing device configured as described above is started and the developer carrier having a film containing molybdenum disulfide formed on the surface rotates in a predetermined direction, the developer in the developer accommodating chamber is moved to the developer carrier. It is carried on the surface, that is, the surface of the film containing molybdenum disulfide, and is conveyed to the development area.
At this time, the developer carrier rotates without adhering the fine powder developer or the resin in the developer due to the crystal structure and the like of molybdenum disulfide contained in the film on the surface of the developer carrier, and the developer The layer is carried uniformly and transported to the development area.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view of an embodiment in which the present invention is applied to a developing device using a toner 5 as a one-component insulating magnetic developer.

Reference numeral 1 in the figure denotes a photosensitive drum that carries an electrostatic latent image and rotates in the direction of arrow A as an electrostatic latent image carrier, and may have or may not have an insulating layer on the surface. Of course, not only the drum shape but also a sheet shape and a belt shape are possible. Reference numeral 2 denotes a sleeve as a developer carrying member which carries the toner 5 on the surface and rotates in the direction of arrow B. The multipolar permanent magnet 3 is fixed inside the sleeve 2 so as not to rotate. Further, a coating 10 containing molybdenum disulfide, which will be described later, is formed on the surface of the sleeve 2 by about 0.1.
It is formed to a thickness of 5 μm to 30 μm. Reference numeral 4 denotes a developer storage chamber for storing the toner 5 and bringing the toner 5 into contact with the surface of the sleeve 2. Reference numeral 6 denotes an iron doctor blade as a member for regulating the layer of the toner 5 on the surface of the sleeve 2 carried in the developer accommodating chamber 4 to a predetermined thickness, and a gap between the surface of the sleeve 2 and the doctor blade 6 is formed. About 50μm ~
It is arranged to be 500 μm.

When the developing device configured as described above is activated and the sleeve 2 rotates in the direction of arrow B, the toner 5 in the developer accommodating chamber 4 is brought into contact with the toner 5 on the photosensitive drum 1 by contact friction between the toner 5 and the surface of the sleeve 2. Is applied to the toner 5 and applied to the surface of the sleeve 2. The toner layer applied to the sleeve surface is further uniformly and thinly layered (layer thickness is about 30 μm) by a doctor blade 6 disposed opposite to one magnetic pole (S pole in the figure) position of the multipolar permanent magnet 3. ~ 300 μm)
It is transported to a developing area formed by the photosensitive drum 1 and the sleeve 2. At this time, by adjusting the rotation speed of the sleeve 2, the surface speed and preferably the internal speed of the toner layer are set to be substantially equal to or close to the speed of the surface of the photosensitive drum 1. Note that the doctor blade 6 may form a facing magnetic pole using a permanent magnet instead of iron. Further, in the developing area, an AC bias may be applied between the sleeve 2 and the surface of the photosensitive drum 1 so that the toner 5 on the sleeve 2 may fly toward the photosensitive drum.

Here, the coating 10 formed on the sleeve surface will be described.

As the coating 10 in this embodiment, a coating-forming polymer material containing molybdenum disulfide and conductive amorphous carbon is used.

Molybdenum disulfide used in the present example is the most common sulfide and naturally exists as molybdenite, a graphite-like solid, the structure is a layered lattice of Mo and S, and the interatomic distance Mo-S Is 2.41Å, specific gravity 4.80, hardness 1-1.5, semiconductor (1
0 ⁶ Ω · cm).

In addition, experiments by the inventors have revealed that molybdenum disulfide used in the present example preferably has an average particle size of 0.5 μm to 10 μm.

The film-forming polymer material is, for example, a styrene resin, a vinyl resin, a polyether sulfone resin, a polycarbonate resin, a polyphenylene oxide resin, a polyamide resin, a fluororesin, a thermoplastic resin such as an acrylic resin,
A thermosetting resin such as an epoxy resin, a polyester resin, an alkyd resin, a phenol resin, a melamine resin, a polyurethane resin, a urea resin, a silicone resin, and a polyimide resin, or a photocurable resin can be used. Among them, those having excellent releasability such as silicone resin and fluorine resin, or those having excellent mechanical properties such as polyether sulfone, polycarbonate, polyphenylene oxide, polyamide, phenol, polyester, polyurethane and styrene resin are more preferable. .

On the other hand, 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 has excellent electric conductivity, and is widely used because it can be filled with a polymer material to impart conductivity, or by controlling the amount of addition, a certain degree of conductivity can be obtained. According to the experiments of the present inventors,
The particle diameter of the conductive amorphous carbon used in the present embodiment is preferably 10 μm to 80 μm, and 15 μm to 40 μm.
m was found to be more preferred.

Next, regarding the film 10 formed on the surface of the sleeve 2,
The experiments performed by the present inventors will be described based on the experimental results in Table 2 attached.

In this experiment, each film treated with molybdenum disulfide, conductive amorphous carbon, resin and solvent as shown in Table 1 attached on the surface of the sleeve 2 of the page printer was formed by changing the density, the sleeve memory, and the toner. The comparison is made for each item of fusion and paint stability.

In each treatment shown in Table 1, molybdenum disulfide having an average particle size of about 4.5 μm was used, and a phenol resin was used as the resin. The solvent used was a mixed solvent of methanol, methylcellosolve, and butanol in a ratio of 1: 1 to 1: 1.
In this experiment, the above contents were mixed with glass beads for 24 hours.
After dispersing with a paint shaker for a period of time, pass through a nylon mesh (300 μm) to form a paint, adhere them to an aluminum cylinder uniformly by air spraying so as to have a thickness of 10 μm. After drying for 30 minutes, the sleeve 2 was obtained.

First, the experimental results of the concentration change will be described.
As shown in the figure, a stable concentration is obtained for treatment methods 1 to 3, but a slight decrease in concentration is observed in treatment method 4 and a marked decrease in concentration is observed in treatment methods 5 and 6. When the concentration change was observed again under the condition of low humidity, the difference between them was further widened. In addition, even in a high temperature and high humidity condition, stable concentrations were obtained in the treatment methods 1 to 3. In addition, no unevenness was observed on the toner coat surface even in all environments.

From this result, it is clear that the decrease in concentration is related to the content of molybdenum disulfide in each treatment method. As described above, molybdenum disulfide is a layered compound. For example, as shown in FIG. 5, the crystal plane is exposed on the surface layer of the coating 10 formed on the surface of the sleeve 2, and the crystal fragments 8 are easily formed. Is considered to prevent the fine powder, binder and the like contained in the toner from being sheared and peeled off. In other words, the fine crystal powder (approximately 0.1 μm to 0.5 μm) contained in the crystal easily slides and separates, and rolls under the toner fine powder (4 μm or less) to always obtain a new developer carrier surface. Can be As a result, an amount of electrostatic charge that does not fluctuate in the environment and does not fluctuate in durability is obtained, and a stable image can be formed.

Next, experimental results of the sleeve memory will be described.
In this experiment, 100 copies of a document having a black band-shaped region X having a width a and a length 1 shown in FIG. 4A were first copied continuously, and then the width shown in FIG. Areas A, B, and C are set in a copy image (FIG. 4 (C)) when a document having a black band-like area Y of length l is copied at b, and any five points in each set area are set. The image density is measured for. The average value of the measurement results was determined, and the results in Table 3 attached as evaluation values for each set area were examined.

Here, the copy image of FIG. 4C will be briefly described. As described above, the original shown in FIG.
After developing the original of FIG. 4B after developing 100 sheets,
A portion C of an area Y in FIG. 4B developed with toner on the sleeve 2 corresponding to a white background other than the area X of the original in FIG. 4A has a higher image density than other image areas. Becomes thinner. The development in which an image like the portion C is formed is called a sleeve memory. The image shown in FIG. 4C is formed in the direction of the arrow in the figure. However, when the sleeve 2 is rotated to develop the original shown in FIG.
Is consumed, the area A after several rotations of the sleeve 2 (C in the figure), specifically, usually after two to three rotations
Means that the image density becomes uniform.

As is evident from the results in Table 3, good results were obtained in treatment methods 1 to 3 having a high molybdenum disulfide content, and particularly in treatment methods having molybdenum disulfide and conductive amorphous carbon. It can be seen that Method 2 is excellent.

Further, resistance (volume resistance) values of the films coated by the treatment method were compared and compared. As shown in Table 3, it can be seen that the volume resistance value of the above treatment method 2 was as low as 7.2 × 10 ¹ (Ωcm). This is considered to be because the electric charge of the fine powder adhered to the sleeve 2 with a strong electrostatic force leaks due to the small volume resistance value of the film and becomes a weak force, and easily separates from the surface on the sleeve.

From the above considerations, the molybdenum disulfide used this time and the conductive amorphous carbon were mixed at each ratio, and the relationship between the volume resistance of the coating and the sleeve memory was examined (No. 3).
Figure).

As is clear from the figure, it is understood that the volume resistance value decreases as the ratio of the carbon content to molybdenum disulfide increases. It also becomes apparent that the sleeve memory improves as the volume resistance decreases.
However, it was also found that the content of the conductive amorphous carbon with respect to molybdenum disulfide is preferably about 40% or less with respect to the stability of the paint described below.

Here, the paint stability is required when a film is formed on the surface of the sleeve 2, particularly when industrial production is performed, and is a pigment to which molybdenum disulfide and conductive amorphous carbon are added, and a binder. The degree to which the resin does not separate. Regarding the paint stability, there is a change depending on the selected resin and its solvent, but the stability is better when the conductive amorphous carbon is contained than the molybdenum disulfide alone. In particular, as apparent from Table 4, the weight ratio of the total content (P) of the molybdenum disulfide content (G) and the conductive amorphous carbon content (C) to the resin content (B) is as follows: It is preferable to satisfy the following relationship: P: B = 40: 10 to 5:10.

Next, the toner fusion on the surface of the sleeve 2 in the experimental results in Table 2 is almost the same as the result after the endurance test for each 10,000 sheets in the density change with respect to the number of copies (FIG. 2) performed when examining the density change. Although similar tendency is shown, toner fusion was not observed in the processing methods 1 to 4 containing molybdenum disulfide.

P, C, G and B that achieve good effects for each item
Are shown in Table 4 attached. In the table, ◎, ○
Indicates that the effects of the present invention can be sufficiently exhibited, and particularly ◎ indicates a more preferable region. In addition, △ indicates a degree that has each defect but has no practical problem, and △ x or × indicates that the effect of the present invention cannot be sufficiently obtained.

For reference, a method for forming a film on the sleeve surface with the molybdenum disulfide particles exposed will be described. As a general method for forming a coating film, there are a dipping method, a spraying method, a roll coating method, a curtain coating method, a sputtering method and the like. In particular, the dipping method and the spraying method are excellent for applying the coating of the present invention. Specifically, in the dipping method, the solidification amount of the paint is reduced from 5% to
The film thickness is adjusted to 0.5 μm to 20 μm by adjusting to 30% and the pulling speed to 50 mm / min to 400 mm / min, and the surface is obtained in a state where molybdenum disulfide is exposed to the surface. In the spray method, air spray was used.
When spraying, the paint pressure cancer 0.1kg / cm ² ~5kg / c
m ^2, was adjusted air pressure pattern adjustment ^{0kg / cm 2 ~5kg / cm 2} , the air pressure for atomizing the ^{0.5kg / cm 2 ~4kg / cm 2} , thickness is that of 0.5μm~20μm Obtained. The resulting coating was obtained by exposing molybdenum disulfide particles to the surface in the same manner as in the dipping method.

The formation of these films was performed using various molybdenum disulfides. As a result, the average particle size of molybdenum disulfide effective to bring about the effect of the present invention is 0.5μ
It was found that those having a size of m to 10 μm were preferable.

The results obtained from each of the experiments described above are summarized as follows.

A coating containing molybdenum disulfide is applied to the surface of the sleeve 2.

The coating has a shape in which molybdenum disulfide is exposed on the surface.

The average particle size of molybdenum disulfide contained in the coating is 0.
5 μm to 10 μm is preferred.

The coating contains conductive amorphous carbon,
The content is preferably 40% by weight or less based on molybdenum disulfide.

Total content of molybdenum disulfide content and conductive amorphous carbon content (P), and resin content (B)
Preferably satisfies the following relationship: P: B = 40: 10-5: 10.

It is preferable that the volume resistance of the coating film is 10 ⁴ (Ωcm) or less.

The one-component insulating developer used in this example is composed of a binder resin, a colorant, and if necessary, additives such as a charge control agent, a fixing aid, and an anti-caking agent. Materials can be used. Examples of the binder resin include, for example, styrene and its substituted homopolymers such as polystyrene and polyvinyltoluene, styrene-based copolymers such as styrene-propylene copolymer and styrene-methyl acrylate copolymer, and polyethyl methacrylate. , An epoxy resin, a phenol resin, an aliphatic or aromatic petroleum resin or the like can be used alone or in combination.

Additives such as a colorant, a charge control agent, a fixing aid, and an anti-caking agent include carbon black, various dyes and pigments, plasticizers, colloidal silica, and talc.

Furthermore, when used as a magnetic developing powder, ferromagnetic elements and alloys containing them as appropriate magnetic powder, alloys and compounds such as, for example, magnetite, hematite, iron such as ferrite, cobalt, nickel, alloys and compounds such as manganese,
Fine powders conventionally known as magnetic materials such as other ferromagnetic alloys can be added.

Further, in the present embodiment, a one-component insulating developer was used as a developer, but not only the developer but also, for example,
It is also possible to apply to a developing device using a two-component developer having a carrier.

[Effect of the Invention] As described above, since the surface of the developer carrying member for carrying and transporting the developer is formed of the film containing at least the film-forming polymer material and molybdenum disulfide. Further, the developer can be uniformly carried on the developer carrying member (sleeve), and the occurrence of density unevenness of an image can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a developing device according to the present invention,
FIG. 2 is a graph showing the relationship between the number of copies and the change in density in the embodiment of the present invention, and FIG. 3 is a graph showing the relationship between the volume resistance of the coating and the sleeve memory, etc., which characterizes the present invention. FIG. 4 is a view for explaining experimental results of the sleeve memory. FIG. 5 is a schematic diagram showing the coating state of the present invention best. DESCRIPTION OF SYMBOLS 1 ... Electrostatic latent image carrier (photosensitive drum) 2 ... Developer carrier 3 ... Multipolar permanent magnet 4 ... Developer storage chamber 5 ... Toner (developer) 6 ... Doctor blade 8 Crystal pieces 10 Coating

Claims (7)

(57) [Claims] A developer accommodating chamber for accommodating a developer; and a developer carrier for contacting the developer accommodated in the developer accommodating chamber and carrying the developer on a surface thereof. In the developing device, the developer carrier conveys the developer carried on the surface to a developing area formed between the surface of the electrostatic latent image carrier and the surface of the developer carrier. Wherein the developer carrier has a surface for supporting and transporting the developer formed of a film containing at least a film-forming polymer material and molybdenum disulfide. . 2. The developing device according to claim 1, wherein the coating is formed such that the molybdenum disulfide is exposed on the surface of the coating. 3. The molybdenum disulfide has an average particle size of 0.5 μm.
The developing device according to claim 1, wherein the thickness is from m to 10 μm. 4. The developing device according to claim 1, wherein the coating has a volume resistivity of 10 ⁴ Ω · cm or less. 5. The coating further comprises a conductive material, wherein the content of the conductive material with respect to molybdenum disulfide is:
5. The developing device according to claim 1, wherein the content is 40% by weight or less. 6. The developing device according to claim 5, wherein said conductive material is carbon black. 7. The film contains a resin as the film-forming polymer material, the molybdenum disulfide and the conductive amorphous carbon, the content of the molybdenum disulfide and the content of the conductive amorphous carbon. The weight ratio of the total amount (P) of the resin to the content (B) of the resin satisfies the following relationship: P: B = 40: 10 to 5:10. 3. The developing device according to claim 1.