JP2004118180A - Developing device, process cartridge and non-magnetic one-component toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-magnetic one-component developer capable of maintaining a constant toner supply amount on a developing roller (2) in view of the above-described problems of a developing device of an image forming apparatus using a conventional non-magnetic one-component developer. To provide a toner and a developing device.
A non-magnetic one-component toner is supported on a peripheral surface, rotates in contact with a latent image carrier, and is formed on the latent image carrier. A developing device including at least a developing roller that supplies the toner to the electrostatic latent image to perform development, and a thin layer forming member that contacts the peripheral surface of the developing roller and thins the toner on the developing roller. Wherein when the frictional force between the developing roller and the toner is F ₁ and the frictional force between the thin layer forming member and the toner is F ₂ , F ₁ <F _2. apparatus.
[Selection] Fig. 2

Description

The present invention relates to a developing device using a non-magnetic one-component toner (in an electrophotographic process) as a developer, a process cartridge detachable to a main body of an image forming apparatus, and a non-magnetic one-component toner.

2. Description of the Related Art In an image forming apparatus using an electrophotographic process such as an electrophotographic copying machine, a printer, and a facsimile, a developing device for developing an electrostatic latent image formed on a latent image carrier (also referred to as a photoconductor) A process cartridge (10) of a non-magnetic one-component developing device (11) is widely used.
An image forming apparatus using the process cartridge (10) will be described with reference to a schematic diagram of one specific example thereof. An arrow (b) comes in contact with the latent image carrier (1) rotating in the direction of the arrow (a). ), A developing roller (2) rotating in a direction, a toner hopper (4) installed in a developing device casing (3), an agitator (5) installed in the hopper (4), and a storage in the hopper (4). The supplied non-magnetic one-component toner is agitated by rotating the agitator (5) and sent to the toner replenishing section (c), and the supplied toner is supplied to the developing roller (2) by a replenishing roller (6). A thin layer forming member (which contacts the developing roller (2) at the upstream end of the developing area in contact with the latent image carrier (1) on the peripheral surface of the roller (2) to thin the toner on the developing roller ( 7).
The non-magnetic one-component toner is triboelectrically charged by the replenishing roller (6) and the thin layer forming member (7), and then is carried by the developing roller (2) and is conveyed to a developing area in contact with the latent image carrier, and the writing light (L), the potential difference between the potential of the electrostatic latent image formed on the latent image carrier (1) and the potential of the developing roller (2) to which the bias voltage has been applied, and the latent image carrier ( 1) Moving up, the electrostatic latent image is developed.

However, if the formation of the thin layer on the developing roller (2) fluctuates and toner is excessively supplied, uncharged toner is generated, and the toner is transferred to a portion of the latent image carrier (1) where there is no charge. This often caused soiling.
As a solution to this, it has been proposed to provide a frictional charging member that is in sliding contact with the developing roller on the upstream side of the thin layer forming member, but there is a drawback that the structure becomes complicated (for example, see Patent Document 1). Further, it has been proposed that the surface of the thin layer forming member be Rz1 to 3 μm, but there is a problem that filming and white streaks easily occur on the thin layer forming member (for example, see Patent Document 2).

JP-A-63-121065 (Claim 1, page 2, upper right column, line 19, line # 2 to page 2, lower left column, line 2) JP-A-5-188748 (claim 1, page 2, right column, lines 13 to 15)

SUMMARY OF THE INVENTION In view of the above-mentioned problems of a developing device in a conventional image forming apparatus using a non-magnetic one-component toner, an object of the present invention is to keep the supply amount of the non-magnetic one-component toner on the developing roller (2) constant. An object of the present invention is to provide a developing device and a process cartridge which can be maintained and a non-magnetic one-component toner used for the same.

That is, the above-mentioned problem is solved by (1) the present invention which is used as one means constituting an electrophotographic image forming apparatus, which carries a non-magnetic one-component toner on a peripheral surface, rotates in contact with a latent image carrier, and A developing roller that supplies the toner to the electrostatic latent image formed on the latent image carrier to develop the electrostatic latent image, and a thin layer that contacts the peripheral surface of the developing roller and reduces the thickness of the toner on the developing roller A developing member provided with at least a forming member, wherein F ₁ <F when the frictional force of the developing roller with the toner is F ₁ and the frictional force of the thin layer forming member with the toner is F _2. a developing device which is a ₂ ', (2) "developing roller and the frictional force F ₁ between the _toner, the difference" F ₂ -F ₁ of frictional force F ₂ between the thin layer forming member and the toner "0 .50 to 2.00 (N), wherein the developing device according to the above (1), 3) "frictional force F ₁ between the developing roller and the _toner, the F _{1 <F 2} relationship frictional force F ₂ between the thin layer forming member and the toner, an image chart of 5% image area after outputting 5000 sheets running And (4) "the developing roller and the toner after the running output of 5000 image charts having a 5% image area". (4) The developing device according to the above (1) or (2), wherein the frictional force _{F 1,} the difference in frictional force _{F 2} between the thin layer forming member and the toner _"F 2 -F _1" is characterized by a 0.50 to 2.00 (N) first (1) (5) The developing device according to any one of the above items (1) to (3), wherein the thin layer forming member has a roller shape. (6) The developing device described above, wherein the thin layer forming roller rotates at a constant peripheral speed. (7) The developing device according to the above (5), wherein the rotation of the thin layer forming roller is one rotation or less per 1,000 A4 size prints. (8) wherein said thin layer forming member is made of an elastic material having a surface roughness Rz of 1 μm or less at least in the vicinity of a portion in contact with said developing roller. The developing device according to any one of the items (7) to (7) ".

Further, an object of the present invention is to provide a process cartridge comprising (9) a latent image carrier and a developing device for developing a latent image on the latent image carrier to form a toner image. According to another aspect of the present invention, there is provided a process cartridge including the developing device according to any one of the above items (1) to (8).

The object of the present invention is to provide (10) the present invention which comprises "at least a resin and a colorant, wherein the resin is mainly composed of any one of a polystyrene resin, a polyester resin, a polyolefin resin or a copolymer thereof. A non-magnetic one-component toner used in the developing device according to any one of the above items (1) to (8) or the process cartridge according to the item (9) ”, (11) The non-magnetic one-component toner according to item (10), wherein the external additive is fixed on the surface, and the toner surface coverage of the external additive is 80% or more and 140% or less. (12) “the non-magnetic one-component toner according to the above (11), wherein the external additive is a mixture of at least two types”, (13) “the at least one type of the external additive Particle size is 40nm or more and 100nm or less It is solved by the second (11) section or the (12) non-magnetic one-component toner according to claim ', characterized in that it.

According to a fourth aspect of the present invention, there is provided the developing device according to any one of the first to eighth aspects or the process cartridge according to the first aspect. An electrophotographic image forming apparatus characterized by the above feature ".

A developing device of the present invention is to solve the above problems, the surface frictional force F ₁ between the developing roller and the _toner, the relationship between the surface frictional force F ₂ between the thin layer forming member and the toner is F _{1 <F 2} It is characterized by the following.

Further, the frictional force _{F 1} between the developing roller and the toner, the difference between the friction force _{F 2} between the thin layer forming member and the toner _"F 2 -F _1" is a 0.50 to 2.00 (N) In this case, it is particularly effective to prevent generation of weakly charged toner.

Measurement of the frictional force F ₂ of the frictional force F ₁ and the thin layer forming member and the toner between the developing roller and the toner of the present invention, as shown schematically in FIG. 3, manufactured by Shinto Scientific Co., Ltd., model number : Using a surface property measuring device of HEIDON-14S as follows.
A sample is prepared by fixing the toner to a single layer on a substrate having a length of 150 mm and a width of 30 mm with an adhesive or a pressure-sensitive adhesive. On the sample, a developing roller or a thin layer forming material as a friction body is arranged, and a load is adjusted so that a linear pressure of 500 g / cm is applied to the developing roller or the thin layer forming material, and the speed is 150 mm / min. And move it by 30 mm in parallel, and measure the average frictional force during the movement.

The friction force in the present invention is considered to be changed by various factors such as friction coefficient between materials, contact area, surface roughness, and the friction force measured by the measuring method is, in addition to these factors, further. It seems that the "rolling" of the external additive must be taken into account.
That is, in the frictional force measurement method used in the present invention, the toner base is fixed and the sample is not affected by “rolling”. However, since the additive is not fixed, the additive is actually used. It is considered that the frictional force is a mixture of the surface frictional force and the rolling frictional force of the additive depending on the presence state.
Additives that are not fixed to the toner matrix exhibit an effect like a rolling bearing to some extent, and as a result, the frictional force is converted into rotational force, and the measured value is reduced.
When the additive is fixed to the toner base by burial or the like, it is considered that the rolling friction disappears and the frictional force becomes almost the surface frictional force of the contact surface.

Therefore, the magnitude of the frictional force in the present invention is greatly affected by the elasticity of the material constituting the surfaces of the developing roller and the thin layer forming member, which are the objects of friction, and the state of the external additive on the toner surface.
When the external additive is not fixed to the toner surface, the frictional force between the material having a high elastic modulus of the material constituting the surface and the toner surface is greatly affected by the rolling when the external additive is not fixed to the toner surface, and the frictional force is reduced. Further, in the case of a material having a low elastic modulus, the rolling of the external additive is eased and the frictional force is increased.
When the relationship between the surface frictional force F1 and the surface frictional force F2 between the thin layer forming member and the toner in the initial state in which the external additive can exist on the toner surface is F1 <F2, the condition for maintaining the relationship after 5000 sheets is as follows. It depends on whether an external additive not embedded exists on the toner surface. The condition under which the external additive is not buried depends on the elastic modulus of the base material, particularly when the particle size of the external additive is less than 50 nm.

The toner of the present invention comprises a toner base mainly composed of a fixing resin and a colorant, and an external additive.
In the toner of the present invention, as an external additive (fluidity imparting agent) to be added and mixed, for example, a lubricant such as polytetrafluoroethylene-based fluororesin, zinc stearate or an abrasive such as cerium oxide or silicon carbide, or For example, a conductivity-imparting agent such as carbon black and tin oxide, a fixing aid such as low-molecular-weight polyolefin and wax, and, for example, colloidal silica, aluminum oxide, and titanium oxide can be used.
The addition amount of the external additive is from 0.1% by weight to 10% by weight, preferably from 0.2% by weight to 5% by weight, based on the toner.
The surface coverage by the external additive is expressed as follows by the ratio of the surface area of the toner base to the total projected area of each external additive.

The surface coverage of the external additive in the non-magnetic one-component toner of the present invention is preferably 80% to 140%.
If the external additive surface coverage is 80% or less, stress on the external additive during the formation of a thin layer is difficult to disperse, and the toner is easily buried in the mother toner. On the other hand, if the ratio is 140% or more, the external additive may float from the toner matrix and may easily cause poor charging due to adhesion to the developing roller.
According to a study by the present inventors, in a conventional non-magnetic one-component toner, if the external additive coating ratio not in excess of 100 percent, the difference between F ₂ and F ₁ I slave is so big However, it is considered that both show close values.

In the toner of the present invention, the particle size of the external additive is preferably 40 nm or more and 100 nm or less. Even when a plurality of external additives are used, it is preferable that the particle size of at least one of the external additives is 40 nm or more and 100 nm or less.
An external additive having a thickness of 40 nm or less is easily buried in the toner matrix, and an external additive having a thickness of 100 nm or more significantly lowers the fluidity of the toner.

As the fixing resin used in the present invention, those conventionally used as binder resins for toner can be applied.
Specifically, a homopolymer of styrene such as polystyrene, polychlorostyrene, and polyvinyl toluene and a substituted product thereof; styrene / p-chlorostyrene copolymer, styrene / propylene copolymer, styrene / vinyltoluene copolymer, Styrene / vinyl naphthalene copolymer, styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, styrene / octyl acrylate copolymer, styrene / methyl methacrylate copolymer Polymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene / α-chloromethyl methacrylate copolymer, styrene / acrylonitrile copolymer, styrene / vinyl methyl ether copolymer, styrene / Vinyl methyl ketone copolymer, Styrene-based copolymers such as len / butadiene copolymer, styrene / isoprene copolymer, styrene / acrylonitrile / indene copolymer, styrene / maleic acid copolymer, styrene / maleic ester copolymer; polymethyl methacrylate , Polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyvinyl butyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin and the like.

The toner of the present invention may contain a release agent.
As the release agent used, those conventionally used can be applied, and in addition to synthetic waxes such as low molecular weight polyethylene and polypropylene, candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil, etc. Vegetable waxes; animal waxes such as beeswax, lanolin, and spermaceti; mineral waxes such as montan wax and ozokerite; oily waxes such as hydrogenated castor oil, hydroxystearic acid, fatty acid amides, and phenol fatty acid esters. And the like.

Further, as the coloring agent used in the toner of the present invention, conventionally used pigments and dyes are applied.
Specifically, ultramarine, nigrosine dye, aniline blue, calco oil blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, phthalocyanine green, rhodamine 6C lake, quinacridone, benzidine yellow, malachite green, hansa yellow G, malachite Examples include green hexalate, oil black, azo oil black, rose bengal, monoazo dyes and pigments, disazo dyes and pigments, and trisazo dyes and pigments.

In the toner of the present invention, it is effective to add a charge control agent to control the polarity. Examples of the charge control agent in this case include nigrosine, quaternary ammonium salts, metal-containing azo dyes, and complex compounds of salicylic acid.

The thin layer forming member constituting the developing device of the present invention is preferably in the form of a roller and rotates at a constant peripheral speed. As a result, filming on the thin layer forming member is prevented, and fluctuation in frictional force is reduced.
At least the vicinity of the portion of the thin layer forming member that contacts the developing roller preferably has high smoothness, and the surface roughness Rz is preferably 1 μm or less. If the surface roughness in the vicinity of the contact is large, the flow of the toner is partially blocked, which may cause white stripes.
The material constituting the surface of the thin film forming member of the present invention is an elastic material.
When the developing roller and the thin layer forming member are brought into a compact state, a distortion is formed in the thin layer forming member, which becomes a gap, the toner passes, and the distortion flows, and the flow of the toner flows. The effect of uniformizing and preventing white stripes can be brought about, and it is particularly effective when the thin layer forming member is made of an elastic material.

As is apparent from the detailed and specific explanations made above, according to the present invention, the toner supply amount in the non-magnetic one-component developing device is kept constant, and a stable thin layer can be formed. It can be prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Parts represent parts by weight.
FIG. 2 shows the thin layer forming member (7) of the detachable process cartridge (10) in the developing device (11) and the developing device main body of FIG. 1 is an example of a developing device to which the present invention is applied and a process cartridge detachable from a developing device main body.

Example 1
Fixing resin: 90 parts of aromatic polyester resin (Tg = 61 ° C)
Colorant: carbon black 7 parts Charge control agent: 2-acrylamido-2-methylpropanesulfonic acid 3,4-dichlorophenylmaleimidoacrylic acid butyl ester 3 parts The mixture having the above composition is melt-kneaded, cooled, and then coarsely milled using a hammer mill. It was pulverized and then pulverized with a pulverizer using an air jet method. The obtained finely pulverized product was classified to obtain a toner base having an average particle size of 7 μm.
Further, for 100 parts of the toner base,
2.4 parts of hydrophobic silica (HDK-2000 manufactured by Hoechst: particle size of about 20 nm)
0.6 parts titanium oxide (SMT-150AI manufactured by Teica: particle size: about 20 nm)
Was added and mixed to obtain a toner.
The external additive coverage of this toner was 133%.

Example 2
With respect to the toner matrix of Example 1,
1.2 parts of hydrophobic silica (HDK-2000 manufactured by Hoechst: particle size of about 20 nm)
0.6 parts of titanium oxide (SMT-150A manufactured by Teica Co., Ltd .: particle size of about 20 nmI)
Was added and mixed to obtain a toner.
The external additive coverage of this toner was 80%.

Example 3
With respect to the toner matrix of Example 1,
1.2 parts of hydrophobic silica (HDK-2000 manufactured by Hoechst: particle size of about 20 nm)
0.6 parts titanium oxide (SMT-150AI manufactured by Teica: particle size: about 20 nm)
1.0 part of surface-treated silicon dioxide (RX50 manufactured by Nippon Aerosil Co., Ltd .: particle size of about 60 nm)
Was added and mixed to obtain a toner.
The external additive coverage of this toner was 94%.

Example 4
With respect to the toner matrix of Example 1,
1.2 parts of hydrophobic silica (HDK-2000 manufactured by Hoechst: particle size of about 20 nm)
0.6 parts titanium oxide (SMT-150AI manufactured by Teica: particle size: about 20 nm)
0.5 parts of surface-treated silicon dioxide (RX50 manufactured by Nippon Aerosil Co., Ltd .: particle size of about 60 nm)
Was added and mixed to obtain a toner.
The external additive coverage of this toner was 87%.

Example 5
After the toner of Example 3 was supplied into the developing device and 5000 sheets of the image chart having a 5% image area were output for 5000 sheets, the toner remaining in the toner hopper was taken out.
At this time, when the toner was observed with a SEM, the external additives of 20 nm were all buried in the toner matrix, but the external additives of 60 nm were not buried.

Comparative Example 1
The toner of Example 1 was replenished into the developing device, and after 5000 sheets of the image chart with a 5% image area were output for running, the toner remaining in the toner hopper was taken out.
At this time, when the toner was observed with an SEM, all the external additives were buried in the toner matrix.

Comparative Example 2
The toner of Example 1 was replenished into the developing device, and after idling the developing device for 60 minutes, the toner was taken out.
At this time, when the toner was observed with an SEM, all the external additives were buried in the toner matrix.

Comparative Example 3
With respect to the toner matrix of Example 1,
0.6 parts of hydrophobic silica (HDK-2000 manufactured by Hoechst: particle size: about 20 nm)
0.3 parts titanium oxide (SMT-150AI manufactured by Teica: particle size: about 20 nm)
Was added and mixed to obtain a toner.
The external additive coverage of this toner was 40%.

In Examples 1 to 5 and Comparative Examples 1 to 3, the frictional force F ₁ between the toner and the developing roller, the frictional force F ₂ between the thin layer forming roller, and the difference “F ₂ −F ₁ ”, and the toner in the developing device. And the results of evaluation of the amount of toner per unit area of the developing roller and the presence / absence of background contamination when the toner is supplied and developed are shown in Table 1.

FIG. 1 is a cross-sectional view illustrating a configuration of an example of a developing device to which the present invention is applied, together with a vicinity of a photoconductor. It is a top view showing the example using the thin layer forming roller for the thin layer forming member of the example of the present invention. It is a top view of the surface property measuring device of HEIDON-14S used by this invention.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 photoconductor 2 developing roller 3 developing device casing 4 toner hopper 5 agitator 6 supply roller 7 thin layer forming member 8 transfer charger 9 thin layer forming roller 10 process cartridge 11 developing device a photoconductor rotating direction b developing roller rotating direction c Toner replenishing section L Write light

Claims (14)

An electrostatic latent image formed on the latent image carrier, which is used as one means of forming an electrophotographic image forming apparatus, carries a non-magnetic one-component toner on a peripheral surface, rotates in contact with the latent image carrier, and rotates. A developing roller that supplies and develops the toner to the developing roller, and a thin layer forming member that contacts the peripheral surface of the developing roller and thins the toner on the developing roller. When the frictional force between the developing roller and the toner is F ₁ and the frictional force between the thin layer forming member and the toner is F ₂ , F ₁ <F ₂ . Wherein the frictional force _{F 1} between the developing roller and the toner, the difference in frictional force _{F 2} between the thin layer forming member and the toner _"F 2 -F _1" is 0.50 to 2.00 (N) The developing device according to claim 1. Frictional force F ₁ between the developing roller and the _toner, the F _{1 <F 2} relationship frictional force F ₂ between the thin layer forming member and the toner, also keeping the image chart of 5% image area after outputting 5000 sheets running The developing device according to claim 1, wherein: Frictional force between 5% developing roller after outputting 5000 sheets running an image chart of an image area and toner F _1, the difference in frictional force F ₂ between the thin layer forming member and the toner "F ₂ -F _1" is 0. The developing device according to any one of claims 1 to 3, wherein the value is 50 to 2.00 (N). The developing device according to claim 1, wherein the thin layer forming member has a roller shape. The developing device according to claim 5, wherein the thin layer forming roller rotates at a constant peripheral speed. 7. The developing device according to claim 6, wherein the rotation of the thin layer forming roller is one rotation or less for 1000 sheets of A4 size print. 8. The developing device according to claim 1, wherein the thin layer forming member is made of an elastic material having a surface roughness Rz of at least 1 μm or less in the vicinity of a portion in contact with the developing roller. 9. A process cartridge comprising: a latent image carrier; and a developing device for developing a latent image on the latent image carrier to form a toner image, wherein the developing device is used as the developing device. A process cartridge comprising the developing device according to (1). 9. The method according to claim 1, comprising at least a resin and a colorant, wherein the resin is mainly composed of any one of a polystyrene resin, a polyester resin, a polyolefin resin, and a copolymer thereof. A non-magnetic one-component toner used in the developing device according to claim 9 or the process cartridge according to claim 9. 11. The non-magnetic one-component toner according to claim 10, wherein an external additive is fixed on the surface, and the toner surface coverage of the external additive is 80% or more and 140% or less. The non-magnetic one-component toner according to claim 11, wherein the external additive is a mixture of at least two kinds. 13. The non-magnetic one-component toner according to claim 11, wherein at least one type of the external additive has a particle size of 40 nm or more and 100 nm or less. An electrophotographic image forming apparatus comprising the developing device according to claim 1 or the process cartridge according to claim 9.

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