JP4815619B2 - Image forming method and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming technique such as a copying machine, a printer, and a facsimile receiver, and more particularly to an image forming technique using a developing roller.

  In an electrophotographic image forming method, an image is usually formed on a transfer sheet through the following steps. In other words, the charged toner is supplied in contact or non-contact with the electrostatic latent image formed on the electrostatic latent image carrier represented by the electrophotographic photosensitive member to visualize the electrostatic latent image. The toner image on the electrostatic latent image carrier is transferred to a sheet or the like, and then fixed to form a final image.

  Development methods for forming a toner image on an electrostatic latent image carrier include a two-component development method using a two-component developer composed of a carrier and a toner, and a one-component developer composed only of a toner. There is a one-component development method used. In the developing method of the one-component developing system, the toner is rubbed and pressed against the charging member or the developing roller surface without using a carrier to be charged, and there is an advantage that the structure of the developing device can be simplified and made compact. In particular, the full-color image forming apparatus in which a plurality of developing devices such as yellow, magenta, cyan, black, etc. are arranged in a limited space with respect to the trend of colorization of toner images is prominent in non-magnetic one-component image formation. is there. In addition, full-color pictorial images can be formed by using so-called polymerized toner that can be produced while controlling the particle size and shape of the toner in the manufacturing process (see, for example, Patent Document 1).

  The developing roller used for non-magnetic single-component image formation has, for example, a form in which a resin layer is provided on a rubber layer provided on the outer periphery of the shaft, and the toner is thinned by a metal plate or a roller on the developing roller. A layer is formed. The toner thin layer formed on the developing roller is charged by the action of friction from the above-described metal plate or roller.

The developing roller is required to have a stable charge imparting performance to the toner and good toner transportability. For this reason, it has been performed so far to impart an appropriate roughness to the surface of the developing roller. For example, the surface of the developing roller is formed using a base material mixed with inorganic compound particles, and the ten-point average roughness, maximum height, arithmetic average roughness, and the like are set within a specific range. There is a controlled developing roller technology (see, for example, Patent Documents 2 and 3).
JP 2000-214629 A JP 2003-15401 A JP 2001-296735 A

  By the way, in the developing device, a stable charge imparting performance to the toner is expressed by forming a uniform toner layer on the developing roller using a regulating member or the like. At this time, since the toner layer is formed on the surface of the developing roller while stirring and sliding the toner, strong stress is applied to the toner, and there is a concern that the toner strongly adheres to the surface of the developing roller. If toner adheres strongly to the surface of the developing roller, the surface of the developing roller becomes slippery due to filming, and the toner conveyance amount is reduced.

  Therefore, there has been a demand for a developing roller that can stably charge the toner without causing toner adhesion due to filming. However, if the toner is stirred and slid so that the toner is not stressed, the toner has sufficient chargeability. Can no longer be granted. As described above, there has been a demand for an image forming technique that does not cause toner adhesion due to filming on the surface of the developing roller and that allows the toner to exhibit stable charging performance.

  An object of the present invention is to provide an electrophotographic image forming method capable of performing stable toner charging without causing toner adhesion due to filming on the surface of a developing roller. That is, the present invention uses a developing roller whose surface property is specified using roughness-imparting particles, so that stable toner conveyance and toner can be achieved without causing filming even in the case where printing is continuously performed. An object is to provide an image forming method capable of charging.

  Specifically, an object of the present invention is to provide an image forming method capable of forming a good toner image without image defects such as fogging, gathering, chipping, and density unevenness due to variations in the amount of toner transport accompanying filming. Is.

  It has been found that the above problems can be solved by the configuration described below.

According to the first aspect of the present invention, “the toner is carried on the surface of the developing roller having the conductive resin layer on the outer periphery of the conductive shaft, and the carried toner is supplied onto the image carrier to provide the image on the image carrier. In an image forming method including a step of developing an electrostatic latent image by a non-magnetic one-component developing method , a developing roller that supplies toner onto the image carrier has roughness-imparting particles that impart roughness to the surface of the developing roller. Contained in the resin layer,
The spacing between the roughness-imparting particles in the resin layer is Sm (μm), the average center line roughness of the resin layer is Ra (μm), and the volume-based median diameter of the toner carried on the resin layer surface is R (μm). )
10R ≦ Sm ≦ 30R
R / 5 ≦ Ra ≦ R / 2
An image forming method having the following relationship: Is the invention.

The invention according to claim 2 is the following: “The toner is carried on the surface of the developing roller having the conductive resin layer on the outer periphery of the conductive shaft, and the carried toner is supplied onto the image carrier to provide the image carrier. In the image forming apparatus having a developing unit for developing the electrostatic latent image on the image carrier by a non-magnetic one-component developing method , the developing roller for supplying toner onto the image bearing member provides roughness to the developing roller surface. Containing imparting particles in the resin layer;
The spacing between the roughness-imparting particles in the resin layer is Sm (μm), the average center line roughness of the resin layer is Ra (μm), and the volume-based median diameter of the toner carried on the resin layer surface is R (μm). )
10R ≦ Sm ≦ 30R
R / 5 ≦ Ra ≦ R / 2
An image forming apparatus having the following relationship: Is the invention.

  According to the present invention, the surface of the developing roller is caused by the stress applied during the toner layer formation by adding the roughness imparting particles so that the surface characteristics of the developing roller are related to the particle size of the toner used for image formation. The problem of toner adhesion to the toner can be avoided. As a result, there is no influence of toner adhesion due to filming in print creation, and the developing roller can stably charge the toner on its surface, and can always carry an appropriate amount of toner, so that stable image formation can be performed. became.

  The present invention relates to an image forming method using a developing roller in which a resin layer containing particles is applied and formed on a conductive shaft. The inventor examined the toner adhesion on the surface of the developing roller by paying attention to the relationship between the roughness state of the surface of the developing roller and the toner adhesion to the roller surface. As a result, it was found that toner adhesion tends to occur at a locally high portion on the surface of the developing roller. And this locally high place is formed because the roughness imparting particles are locally gathered, and it was considered that this problem could be solved if the roughness on the developing roller surface was made uniform. .

  Further, it is assumed that the local adhesion of toner affects not only the surface roughness of the developing roller but also the size of the toner used, and if the surface performance of the developing roller can be correlated with the toner particle size, the developing roller It was thought that toner adhesion to the surface could be avoided.

  By providing a specific relationship between the spacing Sm of the roughness-imparting particles on the surface of the developing roller, the average centerline roughness Ra that specifies the uneven state of the resin layer surface, and the volume-based median diameter R of the toner. The inventors have found that toner adhesion on the surface of the developing roller is avoided.

  That is, by associating the spacing Sm between the roughness-imparting particles on the surface of the developing roller and the volume-based median diameter R of the toner used for image formation as described above, variations in the toner conveyance amount during printing can be suppressed. In addition, since there is no variation in the amount of toner transported by the developing roller, a toner layer having a constant thickness and a uniform thickness is always formed on the developing roller, and the toner charging by the developing roller is maintained at a constant level. It is guessed.

  In addition, by maintaining the toner conveyance amount of the developing roller at a constant level, it is considered that problems such as filming due to an increase in the toner conveyance amount and image density reduction due to a small amount of toner conveyance can be solved. .

  Hereinafter, the present invention will be described in detail.

  In the developing process using the non-magnetic one-component developing method, the toner carried on the developing roller is charged to a predetermined level by the toner regulating member or the developing roller itself, and the toner charged to a predetermined amount is ejected from the surface of the developing roller to make an image. Supply to the carrier is performed. That is, the developing roller used for image formation of the non-magnetic one-component developing system is surely charged with toner on the roller surface, and the electrostatic latent image on the image carrier is made to fly accurately by charging the charged toner. Therefore, it is required to have a performance for developing the toner reliably.

  The developing roller according to the present invention contains roughness imparting particles for imparting roughness to the surface of the developing roller in the resin layer. The developing roller according to the present invention has a conductive resin layer on the outer periphery of a conductive shaft, and has the structure shown in FIG. FIG. 1A shows a structure in which one resin layer is provided around the shaft, and FIG. 1B shows a structure in which the resin layer has a multi-layer structure, in which a resin layer is directly provided on the shaft surface. It is what has.

  As shown in FIG. 1, the developing roller 10 according to the present invention includes a conductive shaft 11 and a resin layer 12 provided on the shaft 11, and the resin layer 12 contains roughness imparting particles 13. Is. The resin layer 12 constituting the developing roller 10 has conductivity, and has a structure in which a conductive substance typified by carbon black is dispersed in the resin. In this way, by dispersing and containing a conductive material such as carbon black in the resin layer 12, a certain degree of conductivity is imparted to the resin layer, and even if electric charges remain on the roller surface, the conductive shaft 11 is provided. It has a structure that is more likely to leak.

  The shaft 11 is composed of a conductive member, and specifically, a metal material such as stainless steel such as SUS304, iron, aluminum, nickel, an aluminum alloy, or a nickel alloy is preferable. Also, a conductive resin in which a conductive material such as the above-described metal powder or carbon black is filled in the resin can be used.

  Here, the roughness imparting particles 13 will be described in detail.

  As a preferable form of the roughness imparting particles 13 contained in the resin layer 12, for example, the average primary particle size is 5 μm or more and 30 μm or less, and the content in the resin layer 12 is 10% by mass or more and 50% by mass or less. Can be cited as one of preferred embodiments.

  The roughness imparting particles 13 can improve the toner transportability on the surface of the developing roller by imparting roughness to the surface of the developing roller.

  The material for the roughness-imparting particles 13 usable in the present invention is not particularly limited as long as it satisfies the relationship described later with the toner used for image formation. Examples of materials that can be used for the roughness imparting particles 13 include styrene resin, styrene acrylic copolymer resin, polyester resin, polyurethane resin, acrylic resin, and polyethylene resin. In the developing roller according to the present invention, the resin layer 12 is preferably formed by applying a resin solution that forms the resin layer 12 on the shaft 11, and the roughness-imparting particles 13 are swollen by the influence of the solvent. What does not do etc. is preferable. From this point of view, it is particularly preferable that the roughness-imparting particles 13 have a structure with excellent solvent resistance such as a crosslinked structure. For example, an acrylic resin having a crosslinked structure is one of the particularly preferable ones.

Next, the intervals between the roughness-imparting particles 13 on the surface of the resin layer 12, that is, on the surface of the developing roller will be described. In the present invention, the interval between the roughness-imparting particles 13 on the surface of the developing roller (the surface of the resin layer 12) (hereinafter, also referred to as the interval between the roughness-imparting particles) is Sm (μm), and the toner to be carried on the surface of the resin layer 12 is used. When the volume-based median diameter is R (μm),
10R ≦ Sm ≦ 30R
Satisfies the relationship.

  The interval Sm between the roughness-imparting particles 13 on the surface of the developing roller corresponds to the “average interval of unevenness” defined in JIS B0601-1994, which defines the surface roughness, and is the intersection where the roughness curve intersects the average line. It is represented by the average value of the interval between the peaks and valleys obtained from the above.

  In other words, from the roughness curve, only the reference length L is extracted in the direction of the average line, and the average value is obtained from the sum of the lengths of the average lines corresponding to one peak and one valley adjacent to it. And is defined by the following formula.

Roughness-granular spacing Sm = (1 / n) ΣSmi
FIG. 2 shows the spacing Sm between the roughness imparting particles 13. In addition, the roughness providing interparticle spacing Sm in the developing roller according to the present invention is preferably 30 μm to 270 μm, and more preferably 65 μm to 200 μm.

Next, the relationship between the average center line roughness in the resin layer of the developing roller and the volume-based median diameter of the toner will be described. In the present invention, the average center line roughness Ra (μm) of the surface of the resin layer 12 formed by the roughness-imparting particles 13 and the volume-based median diameter R (μm) of the toner used for image formation are as follows. It has a relationship. That is,
R / 5 ≦ Ra ≦ R / 2
The average center line roughness Ra on the surface of the developing roller, that is, the average center line roughness Ra in the resin layer 12 corresponds to “arithmetic average roughness” defined in JIS-B0601-1994 that defines the surface roughness. so,
That is, when the reference length L is extracted from the roughness curve in the direction of the average line, the absolute values of deviations from the average line of the extracted portion to the measurement curve (the surface of the resin layer 12) are summed up and averaged. The value obtained is defined as “average centerline roughness” and is defined by the following equation.

Average center line roughness Ra = (1 / L) ∫ | f (x) | dx
FIG. 2 shows the average center line roughness Ra on the surface of the resin layer 12. In the present invention, the average center line roughness Ra is preferably 0.6 μm to 4.5 μm, and more preferably 1.30 μm to 3.30 μm.

  There are no particular limitations on the measuring device for measuring the roughness imparted inter-particle spacing Sm and the average center line roughness Ra on the developing roller surface as long as it can be measured and calculated in accordance with JIS B0610-1994. Specific examples of the surface roughness shape measuring apparatus include “Surfcom (manufactured by Tokyo Seimitsu Co., Ltd.)”.

Thus, in the present invention, between the roughness imparting particle spacing Sm, the average centerline roughness Ra on the developing roller surface, and the volume-based median diameter R of the toner used for image formation,
20R ≦ Sm ≦ 40R
R / 20 ≦ Ra ≦ R / 6
It has the relationship.

  In the present invention, when the above relational expression is established, it is found that toner adhesion does not occur on the surface of the developing roller, and as a result, stable charging is performed on the surface of the developing roller, and at the same time, good The toner can be transported. As described above, the developing roller according to the present invention realizes stable toner charging and conveyance, and image formation by the non-magnetic one-component developing method is smoothly performed.

  The roughness imparting particles 13 will be further described.

  As described above, the size of the roughness-imparting particles 13 is preferably in the range where the average primary particle size is 5 μm or more and 30 μm or less. By making this range, it is expected that the toner transportability on the roller surface will be improved. The That is, when the average primary particle size of the roughness-imparting particles is 5 μm or more and 30 μm or less, and more preferably 10 μm or more and 20 μm or less, appropriate irregularities are formed on the surface of the developing roller, and the roughness imparting particles are not used. A large amount of toner can be held and transported. As a result, the amount of toner supplied onto the image carrier increases, and it is possible to stably form a good toner image having a high density and no unevenness on the image carrier.

  The content of the roughness-imparting particles 13 in the resin layer 12 is preferably 10% by mass or more and 50% by mass or less. By setting the content within this range, the roughness-imparting particles 13 are appropriately dispersed in the resin layer 12. It is expected that the toner can be transported in a uniform amount without unevenness anywhere in the surface of the developing roller where the toner can be transported uniformly. That is, when the content is 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 40% by mass or less, the state in which the roughness imparting particles 13 are uniformly dispersed in the resin layer 12 is formed, and the developing roller The same amount of toner is transported in any of the above parts. As a result, in addition to the configuration of the present invention, it is expected that toner charging at the same level in any part on the developing roller is promoted and toner supply to the image carrier is stably performed. .

  Examples of a method for measuring the average primary particle size of the roughness-imparting particles 13 include a method using a device in which a computer system for data processing is connected to Multisizer 3 (manufactured by Beckman Coulter). The volume-based median diameter (D50v diameter) is calculated by this method, and this is used as the average primary particle diameter of the roughness-imparting particles 13.

The particle size measurement of the roughness imparting particles 13 by the multisizer 3 is performed according to the following procedure.
(1) 0.02 g of the roughness imparting particles 13 is prepared, and 20 ml of a surfactant solution is added thereto. This is for the purpose of dispersing the roughness-imparting particles 13. For example, a surfactant solution prepared by diluting a neutral detergent containing a surfactant component 10 times with pure water is used.
(2) After the roughness-imparting particles 13 are sufficiently conditioned with the surfactant solution, an ultrasonic dispersion treatment is performed for 1 minute to prepare a roughness-imparting particle dispersion.
(3) This roughness-imparting particle dispersion is pipetted into a beaker containing ISOTON II (manufactured by Beckman Coulter) in a sample stand until the measured concentration is 5 to 10%.
(4) Set the measuring machine count to 2500 and start measurement. The aperture diameter of the multisizer 3 is 100 μm.

  The resin layer 12 constituting the developing roller will be further described.

  The resin constituting the resin layer 12 of the developing roller according to the present invention is not particularly limited as long as the dielectric constant has the above-described relationship with the dielectric constant of the roughness imparting particles 13. The dielectric constant ε (sb) of the resin that can be used for the resin layer 12 is, for example, 5.0 to 5.3 for polyurethane resin, 4.5 to 5.5 for phenol resin, and 2.7 to 4. for acrylic resin. 5.

  The surface of the resin layer 12 is a region where a toner layer is formed and the toner is charged by frictional charging, and the resin layer 12 is strong between the shaft 11 so that sufficient toner charging can be stably performed. It is required to have adhesive strength. Examples of the resin that can provide a strong adhesive force with the shaft 11 include the above-described resins. Among them, polyurethane resins are preferable, and polyurethane resins obtained by reacting polyols and isocyanates are particularly preferable. Moreover, when producing this polyurethane-type resin, it is also possible to add a chain extender as needed in addition to a polyol and isocyanate.

  Specific examples of the polyol include polyurethane polyol compounds such as polytetramethylene ether glycol, poly-ε-caprolactone diol, polycarbonate polyol, and polypropylene glycol. Among these, a polycarbonate polyol that forms a polyurethane resin that prevents a decrease in charge amount of the toner during image formation in a high temperature and high humidity environment is preferable. Specifically, aliphatic or alicyclic polycarbonate polyols such as polyhexamethylene carbonate diol are more preferable.

  Specific examples of the isocyanate include 4,4′-diphenylmethane diisocyanate (MDI), cyclohexane diisocyanate, hydrogenated MDI, isophorone diisocyanate, 1,3-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6 -Tolylene diisocyanate etc. are mentioned.

  Moreover, it is also possible to use the urethane prepolymer obtained by making it react so that it may have an isocyanate group in the molecular terminal using the said isocyanate, polyol, and also polyamine.

  Examples of the chain extender include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, isophoronediamine (IPDA), hydrazine, and the like. Can be mentioned.

  A typical production method of the polyurethane resin includes a one-stage method and a two-stage method. The one-stage method is a method for producing a polyurethane resin by reacting a polyol, a diisocyanate compound, and, if necessary, a chain extender or a polymerization terminator in a suitable solvent at a time. In the two-stage method, a prepolymer having an isocyanate group at the end of the polyol chain is prepared by reacting a polyol and a diisocyanate compound in an environment where the isocyanate group is excessive, and then this is chain-extended in a suitable solvent. The reaction is performed in an environment in which an agent and a polymerization terminator are present. Among these, the two-stage method has an advantage that a uniform polymer solution can be easily obtained.

  As a solvent used when producing a polyurethane resin, the following are usually mentioned. Aromatic solvents such as benzene, toluene, xylene; ester solvents such as ethyl acetate and butyl acetate; alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, diacetone alcohol; acetone, methyl ethyl ketone, methyl isobutyl ketone, etc. Examples include ketone solvents, other dimethylformamide, dimethylacetamide, ethylene glycol dimethyl ether, tetrahydrofuran, and cyclohexanone. These organic solvents can be used alone or in combination.

  Moreover, the adhesiveness between the resin layer 12 and the shaft 11 can be obtained by including in the resin layer 12 a compound having a molecular structure in which a resin component called a resin-silica hybrid and a silica component are integrated by molecular bonding. It is also possible to improve. The resin-silica hybrid is composed of a region having a network-like silica structure (also referred to as a silica skeleton in the present invention) by alternating bonds of silicon atoms and oxygen atoms, and a region of an organic polymer composed of a polyurethane resin or a vinyl polymer resin. It is comprised from.

  The resin-silica hybrid forms an alkoxy group-containing silane-modified resin by the reaction of a resin having a functional group reactive with an epoxy group and an epoxy group-containing alkoxysilane partial condensate, and condenses the alkoxy group-containing silane-modified resin. It is cured by reaction to form a silica structure.

  The thickness of the resin layer 12 is preferably set in the range of 1 to 30 μm, and particularly preferably 5 to 20 μm. The thickness of the resin layer can be measured from a cross-sectional sample including the resin layer taken from the developing roller and the micrograph. Further, as shown in FIG. 1B, the developing roller according to the present invention may have a multilayer structure in which the resin layer is composed of a plurality of layers.

  The resin layer 12 constituting the developing roller according to the present invention has conductivity. However, it is possible to impart conductivity by a method in which a conductive material typified by carbon black is included in the resin layer 12. Is possible.

Further, the resin layer 12 is confirmed to have conductivity by its surface resistance value Rs, and the surface resistance value Rs of the developing roller according to the present invention is 1 × 10 ¹⁰ (Ω / □) or more and 1 × 10 ¹³ ( Ω / □) is preferably in the following range. Here, the surface resistance value (Surface Resistivity, unit: Ω / □ (read as ohm per square)) indicates a resistance per unit area on the surface of the developing roller, and is also referred to as a sheet resistance or a surface resistivity.

The surface resistance value Rs of the developing roller can be measured according to JIS K6991 using a circular electrode (for example, “HR probe” of Hiresta IP manufactured by Mitsubishi Oil Chemical Co., Ltd.). A method for measuring the surface resistance value Rs will be described with reference to FIG. FIG. 2 is a schematic plan view (a) and a schematic cross-sectional view (b) showing an example of a circular electrode. The circular electrode shown in FIG. 2 includes a first voltage application electrode A and a plate-like insulator B. The first voltage application electrode A has a cylindrical electrode portion C and a cylindrical ring electrode having an inner diameter larger than the outer diameter of the cylindrical electrode portion C and surrounding the cylindrical electrode portion C at a constant interval. Part D is provided. The developing roller 10 is sandwiched between the cylindrical electrode portion C and ring electrode portion D in the first voltage application electrode A and the plate insulator B, and the cylindrical electrode portion C and ring shape in the first voltage application electrode A are sandwiched. The current I (A) that flows when the voltage V (V) is applied to the electrode part D is measured, and the surface resistance value Rs (Ω / □) of the transfer surface of the developing roller according to the following relational expression (3) Can be calculated. That is,
Relational expression (3) Rs = π × (D + d) / (D−d) × (V / I)
In the formula, d (mm) represents the outer diameter of the cylindrical electrode portion C, and D (mm) represents the inner diameter of the ring-shaped electrode portion D.

  The resin layer 12 constituting the developing roller according to the present invention has conductivity. However, as a method for imparting conductivity to the resin layer 12, a conductive substance typified by carbon black is contained in the resin layer 12. Realization is possible by including. Examples of the conductive substance that can be added to the resin layer 12 include metal powder such as aluminum powder, iron powder, and copper powder in addition to carbon black.

  Hereinafter, the conductivity imparting substance to the resin layer 12 constituting the developing roller according to the present invention and typical carbon black will be described.

  The carbon black that can be used in the developing roller according to the present invention is not particularly limited as long as it can impart appropriate conductivity to the surface of the developing roller. Specific examples of carbon black include furnace black, gas black, channel black, frame black, thermal black, acetylene black, plasma black, Inversion blacks known from DE 19521565, WO 98/45361 or DE 19637396. Si-containing carbon black disclosed in WO 98/42778, metal-containing carbon black disclosed in WO 98/42778, arc discharge black (Lichbogenruss), carbon black obtained as a by-product by a chemical production method, and the like.

  In addition, carbon black and color black used as a reinforcing filler in rubber mixtures, or carbon black used as a reinforcing filler in applications other than rubber such as carbon black and bitumen used to stabilize ultraviolet light, Furthermore, carbon black for fillers in plastics, carbon black used as a reducing agent in metallurgy, and the like can be used as long as they have a conductivity index shown in the following range.

  Moreover, 5-70 mass parts is preferable with respect to 100 mass parts of resin, and, as for content of carbon black, 20-50 mass parts is more preferable.

  The physical properties of carbon black that can be used in the present invention will be described below.

  Further, the conductivity of carbon black can be specified by, for example, an index called a conductivity index shown below. The conductivity index is defined by the following formula, and the carbon black usable in the present invention preferably has a value of 20 or more and 60 or less.

Conductivity index = (specific surface area × DBP oil absorption) ^1/2 / (1 + volatile content)
The conductivity index indicates the degree of conductivity of the carbon black. For example, the smaller the value of the conductivity index, the higher the resistance of the carbon black. The value of the conductivity index can be adjusted by appropriately selecting each factor constituting the above formula, that is, the specific surface area, the DBP oil absorption, and the volatile content.

  Hereinafter, each factor constituting the equation of the conductivity index will be described.

  First, the volatile content (% by mass) in the formula is a value calculated by the ratio of the organic volatile component that comes out when carbon black is heated at 950 ° C. for 7 minutes. Typical examples thereof include oxygen-containing functional groups such as a carboxyl group, a quinone group, a lactone group, and a hydroxyl group.

  The volatile content of carbon black is obtained by measuring and calculating carbon black that has been previously dried at 100 ° C. for 1 hour under a nitrogen gas stream in accordance with JIS K 6221-82. That is, assuming that the volatile content of carbon black is V, the volatile content V is determined by measuring the mass (WD) of carbon black before heating and the mass (WR) of carbon black after heating at 950 ° C. for 7 minutes. Calculated from the formula.

V (mass%) = (WD−WR) / WD × 100
Examples of the volatile component in the carbon black include a carboxyl group, a quinone group, and a lactone group that exist on the surface of the carbon black particles. In the carbon black used in the present invention, the volatile component is 4% by mass or more. Specifically, 5 to 15% by mass is contained.

  Examples of the carbon black having the above characteristics include Printex V (volatile content 12 mass%, pH 3.0), Printex 140 V (volatile content 5 mass%, pH 4.5), Special Black 4 (volatile mass 12 mass) manufactured by Degussa. %, PH 3.0), Cabot MOGUL-L (volatile content 5 mass%, pH 2.5), MONARCH 1000 (volatile content 9.5 mass%, pH 9.5), Mitsubishi Chemical Corporation OIL7B (volatile content 6 mass) %, PH 3.0) and the like.

The specific surface area in the formula is called a nitrogen adsorption specific surface area (N ₂ SA), and measures the total specific surface area of carbon black. In this method, degassed carbon black is immersed in liquid nitrogen, the amount of nitrogen adsorbed on the carbon black surface at equilibrium is measured, and the specific surface area (m ² / g) is calculated from this value by the BET method. is there. The calculation of the nitrogen adsorption specific surface area (N ₂ SA) in the present invention is based on ASTM D3037 88 “Standard Test Method for Carbon Black-Surface Area by Nitrogen Absorption” Method B, which describes the measurement method by low temperature nitrogen adsorption.

Additionally, DBP oil absorption in the formula, the absorption amount of DBP which is a kind of plasticizer (abbreviation of ^{Dibutyl phthalate) (cm 3 / 100g} ), intended to indirectly quantify the fused state between the carbon black particles is there. Calculation of the DBP absorption (cm ³ / 100g) is carried out by applying the ASTM D2414 88 "Standard Test Method for Carbon Black-Oil Absorption Number (OCN)".

  The carbon black is preferably pretreated with an organometallic compound. Typical examples of the metal organic compound used for the surface treatment include an aluminum coupling agent, and other examples include a titanium coupling agent, a silicone coupling agent, and a zirconium coupling agent. . Examples of the surface treatment method for carbon black include a dry method in which carbon black is added to a mixer or the like, and a metal organic compound is added thereto, or a wet method in which both are present in an organic solvent. The surface treatment is performed at room temperature or under heating.

  Specific examples of aluminum-based metal organic compounds, which are representative examples of metal organic compounds used for surface treatment of carbon black, are shown below.

  The usage-amount of a metal organic compound is 0.01-20 mass parts with respect to 100 mass parts of carbon black, Preferably it is 0.1-10 mass parts.

  Next, the developing roller manufacturing method according to the present invention will be described. The developing roller according to the present invention can be produced, for example, by applying a coating solution made of a resin containing roughness-imparting particles around a conductive shaft, and performing a heat treatment after the coating. is there. Further, it is also possible to apply a coating solution on the resin layer and perform the same heat treatment to produce a developing roller having a multilayer structure shown in FIG. Hereinafter, the production procedure of the developing roller according to the present invention will be further described.

  First, a resin layer forming coating solution is prepared by mixing and dissolving a material for forming a resin layer formed around a conductive shaft in an organic solvent. That is, a coating solution containing roughness imparting particles is prepared. If necessary, the resin layer forming solution may contain a material such as carbon black. In this way, a coating solution for forming a resin layer containing roughness imparting particles that impart roughness to the roller surface is prepared.

  Next, the aforementioned coating solution for forming a resin layer is applied on the conductive shaft. As the coating method, various methods can be selected according to the viscosity of the coating solution for forming the resin layer. Specific examples of the coating method include a dipping method, a spray method, a roll coating method, and a brush coating method. In the present invention, these coating methods are not limited.

  After applying the coating solution for forming the resin layer on the conductive shaft, drying and heat treatment (temperature: 120 to 200 ° C., processing time: 20 to 90 minutes) are performed to remove the solvent in the coating solution for forming the resin layer. Thus, a resin layer containing carbon black (conductive resin layer) is formed.

  Further, before and after the formation of the carbon black-containing resin layer by the above procedure, for example, by applying a coating solution such as a coating solution containing a silicone copolymer resin, the development of the multilayer structure shown in FIG. It is also possible to produce a roller.

  Next, toner that can be used for image formation using the developing roller according to the present invention will be described. The toner that can be used for image formation using the developing roller according to the present invention is either a so-called pulverized toner manufactured through a pulverizing / classifying process, or a so-called polymerized toner manufactured directly from a polymerization process for preparing resin particles. Can be used. Among these, in particular, the polymerized toner can be produced while controlling the particle size and shape of the toner during the production process, which is convenient for producing a toner having a small particle size having a uniform shape.

  By using toner with a small particle size that has a uniform shape, it is easy to form a high-resolution and high-definition image as required in digital image formation, and is particularly preferable for, for example, high-gradation pictorial full-color image formation. It is. It is expected that high-definition full-color image formation can be stably produced by combining with the developing roller according to the present invention.

In the present invention, the volume-based median diameter R of toner carried on the resin layer surface of the developing roller surface, the interparticle spacing Sm on the developing roller surface (resin layer surface), and the average center roughness of the developing roller surface (resin layer surface) The following relationship is established between Ra. That is,
10R ≦ Sm ≦ 30R
R / 5 ≦ Ra ≦ R / 2
When the above relational expression is established, it has been found that toner adhesion does not occur on the surface of the developing roller. As a result, stable charging is performed on the surface of the developing roller, and at the same time, good toner conveyance can be performed. It became like. As described above, the developing roller according to the present invention realizes stable toner charging and conveyance, and image formation by the non-magnetic one-component developing method is smoothly performed.

  The volume-based median diameter (D50v diameter) R (μm) of the toner can be measured and calculated using an apparatus in which a computer system for data processing is connected to Multisizer 3 (manufactured by Beckman Coulter). .

The volume-based median diameter R of the toner using the multisizer 3 is measured according to the following procedure.
(1) 0.02 g of toner is prepared, and 20 ml of a surfactant solution is added thereto. This is intended to disperse the toner. Examples of the surfactant solution include those prepared by diluting a neutral detergent containing a surfactant component 10 times with pure water.
(2) After the toner is sufficiently saturated with the surfactant solution, ultrasonic dispersion treatment is performed for 1 minute to prepare a toner dispersion.
(3) This toner dispersion is pipetted into a beaker containing ISOTON II (manufactured by Beckman Coulter) in a sample stand until the measured concentration is 5 to 10%.
(4) Set the measuring machine count to 2500 and start measurement. The aperture diameter of the multisizer 3 is 100 μm.

  In the present invention, it is preferable to use a toner having a volume-based median diameter (D50v diameter) of 3 to 9 μm. The reason for this is that the shape and size of polymerized toners, that is, when performing high-definition digital image formation and pictorial image formation at the photographic image level, which are considered to have many opportunities to be created by a non-magnetic one-component development method, A small-diameter toner having a uniform diameter is preferable. In particular, toner production by a polymerization method capable of producing toner particles while controlling the shape and size is preferable for obtaining a small-diameter toner having a uniform shape and size. Specific methods for preparing the polymerized toner include, for example, those described in JP-A No. 2000-214629, JP-A No. 2001-42564, JP-A No. 2002-116574, and the like.

  Hereinafter, elements constituting a polymerized toner which is an example that can be used for image formation using the developing roller according to the present invention will be described.

(Monomer)
As the polymerizable monomer, a radically polymerizable monomer is an essential component, and a crosslinking agent can be used as necessary. Moreover, it is preferable to contain at least one radical polymerizable monomer having the following acidic group or radical polymerizable monomer having a basic group.
(1) Radical polymerizable monomer The radical polymerizable monomer component is not particularly limited, and a conventionally known radical polymerizable monomer can be used. Moreover, it can be used combining 1 type (s) or 2 or more types so that the required characteristic may be satisfy | filled.

  Specifically, aromatic vinyl monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers , Halogenated olefin monomers and the like can be used.

  Examples of the aromatic vinyl monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples thereof include styrene monomers such as 4-dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.

  Examples of (meth) acrylic acid ester monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylic acid. Examples include butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.

  Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, and vinyl benzoate.

  Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like.

  Examples of the monoolefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene, 4-methyl-1-pentene and the like.

  Examples of the diolefin monomer include butadiene, isoprene, chloroprene and the like.

  Examples of the halogenated olefin monomer include vinyl chloride, vinylidene chloride, vinyl bromide and the like.

(2) Crosslinking agent As the crosslinking agent, a radical polymerizable crosslinking agent may be added to improve the properties of the toner. Examples of the radical polymerizable crosslinking agent include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.

(3) Radical polymerizable monomer having acidic group or basic group As the radical polymerizable monomer having acidic group or radical polymerizable monomer having basic group, for example, a carboxyl group-containing monomer Amine-based compounds such as sulfonic acid group-containing monomers, primary amines, secondary amines, tertiary amines, and quaternary ammonium salts can be used.

  Examples of the radical polymerizable monomer having an acidic group include carboxylic acid group-containing monomers such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, and maleic acid monoester. An octyl ester etc. are mentioned.

  Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfosuccinic acid, octyl allyl sulfosuccinate and the like.

  These may have a structure of an alkali metal salt such as sodium or potassium or an alkaline earth metal salt such as calcium.

  Examples of the radical polymerizable monomer having a basic group include amine compounds, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and quaternary ammonium salts of the above four compounds, 3-dimethylaminophenyl acrylate, 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, piperidylacrylamide, methacrylamide, N-butylmethacrylamide, N-octadecylacrylamide Vinyl pyridine, vinyl pyrrolidone; vinyl-N-methylpyridinium chloride, vinyl-N-ethylpyridinium chloride, N, N-di Lil ammonium chloride, N, may be mentioned N- diallyl-ethyl chloride or the like.

  As the radical polymerizable monomer, it is preferable to use a radical polymerizable monomer having an acidic group or a radical polymerizable monomer having a basic group in an amount of 0.1 to 15% by mass of the whole monomer, The radical polymerizable cross-linking agent is preferably used in the range of 0.1 to 10% by mass with respect to the total radical polymerizable monomer, although it depends on its characteristics.

(Chain transfer agent)
For the purpose of adjusting the molecular weight, it is possible to use a commonly used chain transfer agent.

  The chain transfer agent is not particularly limited, and for example, octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, n-octyl-3-mercaptopropionic acid ester, carbon tetrabromide and styrene dimer are used.

(Polymerization initiator)
The radical polymerization initiator can be appropriately used as long as it is water-soluble. For example, persulfate (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2-amidinopropane) salt, etc.), A peroxide compound etc. are mentioned.

  Furthermore, the radical polymerization initiator can be combined with a reducing agent as necessary to form a redox initiator. By using a redox initiator, the polymerization activity is increased, the polymerization temperature can be lowered, and the polymerization time can be further shortened.

  The polymerization temperature may be any temperature as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator. For example, a range of 50 ° C. to 90 ° C. is used. However, it is also possible to polymerize at room temperature or slightly higher temperature by using a polymerization initiator that starts at room temperature, for example, a combination of hydrogen peroxide and a reducing agent (ascorbic acid or the like).

(Surfactant)
In order to perform polymerization using the above-mentioned radical polymerizable monomer, it is necessary to perform oil droplet dispersion in an aqueous medium using a surfactant. Although it does not specifically limit as surfactant which can be used in this case, The following ionic surfactant can be mentioned as an example of a suitable thing.

  Examples of ionic surfactants include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6 Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sodium sulfonate, etc.), sulfuric acid Ester salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate) Beam, calcium oleate and the like).

  Nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester Etc. These are mainly used as an emulsifier at the time of emulsion polymerization, but may be used for other processes or purposes.

(Coloring agent)
Examples of the colorant include inorganic pigments, organic pigments, and dyes.

  A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.

  Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

  Conventionally known organic pigments and dyes can also be used. Specific organic pigments and dyes are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 156, and the like.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  As the dye, C.I. I. Solvent Red 1, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Solvent Red 58, C.I. I. Solvent Red 63, C.I. I. Solvent Red 111, C.I. I. Solvent Red 122, C.I. I. Solvent Yellow 19, C.I. I. Solvent Yellow 44, C.I. I. Solvent Yellow 77, C.I. I. Solvent Yellow 79, C.I. I. Solvent Yellow 81, C.I. I. Solvent Yellow 82, C.I. I. Solvent Yellow 93, C.I. I. Solvent Yellow 98, C.I. I. Solvent Yellow 103, C.I. I. Solvent Yellow 104, C.I. I. Solvent Yellow 112, C.I. I. Solvent Yellow 162, C.I. I. Solvent Blue 25, C.I. I. Solvent Blue 36, C.I. I. Solvent Blue 60, C.I. I. Solvent Blue 70, C.I. I. Solvent Blue 93, C.I. I. Solvent blue 95 etc. can be used and these mixtures can also be used.

  These organic pigments and dyes can be used alone or in combination as desired. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

(wax)
In the polymerized toner, wax may be contained in the toner particles. There is no particular limitation on the structure and composition of the wax itself. Low molecular weight polyolefin waxes such as polypropylene and polyethylene, paraffin wax, Fischer-Tropsch wax, ester wax and the like can be used.

  The addition amount is 1 to 30% by mass, preferably 2 to 20% by mass, and more preferably 3 to 15% by mass with respect to the whole toner.

  As a toner that can be used for image formation using the developing roller according to the present invention, a toner in which wax is dissolved is dispersed in water and polymerized to form particles in which wax is encapsulated in resin particles. The toner is preferably salted out / fused with the colorant particles to form a toner.

  The toner of the present invention comprises a step of dispersing a monomer solution in which wax is dissolved in an aqueous medium, and then preparing resin particles containing a release agent by a polymerization method, and using the resin particle dispersion liquid in an aqueous medium. The step of fusing the resin particles in step, the step of filtering the obtained particles from an aqueous medium to remove the surfactant, the step of drying the obtained particles, and the external addition to the particles obtained by drying It is preferable to produce by a polymerization method composed of an external additive addition step of adding an agent and the like. Here, the resin particles may be colored particles. Further, non-colored particles can also be used as resin particles. In this case, colored particles are formed by adding a colorant particle dispersion or the like to a dispersion of resin particles and then fusing in an aqueous medium.

  In particular, the method of fusing is preferably a method of salting out / fusing using resin particles produced by the polymerization step. When non-colored resin particles are used, the resin particles and the colorant particles can be salted out / fused in an aqueous medium.

  In addition to the colorant and the release agent, a charge control agent that is a component of the toner can be added as particles in this step.

  In addition, an aqueous medium here consists of water as a main component, and shows content whose water content is 50 mass% or more. Examples of those other than water include organic solvents that dissolve in water, and examples include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran.

  As a preferred polymerization method in the present invention, a monomer solution in which a release agent is dissolved in a monomer is dispersed in oil droplets by mechanical energy in an aqueous medium in which a surfactant having a critical micelle concentration or less is dissolved. A method may be mentioned in which a water-soluble polymerization initiator is added to the dispersion and radical polymerization is performed. In this case, an oil-soluble polymerization initiator may be added to the monomer.

  The disperser for performing the oil droplet dispersion is not particularly limited, and examples thereof include CLEARMIX, ultrasonic disperser, mechanical homogenizer, manton gourin, pressure homogenizer, and the like.

  As described above, the colorant itself may be used after surface modification. In the surface modification method of the colorant, the colorant is dispersed in a solvent, and after the surface modifier is added therein, the temperature is raised and the reaction is performed. After completion of the reaction, the mixture is filtered, washed with the same solvent, repeatedly filtered and dried to obtain a pigment treated with a surface modifier.

  There is a method in which the colorant particles are prepared by dispersing a colorant in an aqueous medium. This dispersion is performed in a state where the surfactant concentration in water is equal to or higher than the critical micelle concentration (CMC).

  Disperser at the time of pigment dispersion is not particularly limited, but preferably a medium such as Clairemix, ultrasonic disperser, mechanical homogenizer, pressure disperser such as Manton Gorin or pressure homogenizer, sand grinder, Getzmann mill, diamond fine mill, etc. Type disperser.

  As the surfactant used here, the aforementioned surfactants can be used.

  In the step of salting out / fusion, a salting-out agent composed of an alkali metal salt or an alkaline earth metal salt is added as a flocculant having a critical coagulation concentration or more in water in which resin particles and colorant particles are present. Next, it is a step of performing fusion at the same time as salting-out proceeds by heating the resin particles to a temperature higher than the glass transition point.

  Here, the alkali metal salt and the alkaline earth metal salt which are salting-out agents include lithium, potassium, sodium and the like as the alkali metal, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium. Preferably, potassium, sodium, magnesium, calcium, and barium are used. Examples of the salt include chlorine salt, bromine salt, iodine salt, carbonate salt, sulfate salt and the like.

  In addition to the resin, the colorant, and the release agent, the toner may be added with a material that can impart various functions as a toner material. Specific examples include charge control agents. These components can be added simultaneously with the resin particles and the colorant particles in the salting out / fusion step described above, and can be added by various methods such as a method included in the toner and a method of adding to the resin particles themselves.

  Similarly, various known charge control agents and those that can be dispersed in water can be used. Specific examples include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.

  To the toner of the present invention, so-called external additives can be added and used for the purpose of improving fluidity, chargeability and cleaning property. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used. Usually, the particles before adding these external additives are often called colored particles, and the particles after the addition are often called toner or toner particles. However, both may be toner or toner particles.

  A conventionally well-known thing can be used as an inorganic fine particle. Specifically, silica, titanium, alumina fine particles and the like having a number average primary particle diameter of 5 to 500 nm can be preferably used. These inorganic fine particles are preferably hydrophobic.

  Specifically, as silica fine particles, for example, commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK-2150, H manufactured by Hoechst -200, commercially available products TS-720, TS-530, TS-610, H-5, MS-5 and the like manufactured by Cabot Corporation.

  Examples of the titanium fine particles include commercial products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercial products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, and JA- 1. Commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT- manufactured by Idemitsu Kosan Co., Ltd. OC etc. are mentioned.

  Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd. and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

  As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As this, a homopolymer such as styrene or methyl methacrylate or a copolymer thereof can be used.

  Examples of lubricants include, for example, zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, manganese, iron, copper, magnesium, etc., zinc palmitate, copper, magnesium, calcium, etc. And salts of higher fatty acids such as zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.

  The amount of these external additives added is preferably 0.1 to 5% by mass with respect to the toner.

  As a method for adding the external additive, various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer can be used.

  Next, the image forming method according to the present invention will be described. The developing roller according to the present invention is preferably used in an image forming apparatus using a non-magnetic one-component developer that forms an image without using a carrier.

  The developing roller according to the present invention is mounted in a developing device that supplies toner onto an image carrier that forms an electrostatic latent image. The developing device has a toner layer regulating member and a toner replenishing auxiliary member in addition to the developing roller according to the present invention, and these members are arranged so as to contact each other. In the developing device, a thin toner layer is formed on the developing roller by the toner layer regulating member and the toner replenishing auxiliary member, and this is supplied onto the image carrier to visualize the latent image formed on the image carrier. .

  The toner layer regulating member supplies the toner in a uniform thin layer state on the developing roller and frictionally charges the supplied toner. The toner layer regulating member is a member having a certain degree of elasticity, such as urethane rubber or a metal plate, and forms a thin layer of toner on the developing roller by contacting the developing roller. The toner thin layer formed on the developing roller has a maximum thickness of 10 toner particles, preferably 5 or less.

  The contact force of the toner layer regulating member to the developing roller is preferably 10 N / m to 50 N / m, and more preferably 15 N / m to 40 N / m. By setting the contact force within this range, the toner can be conveyed without causing unevenness in conveyance, so that the occurrence of image defects such as white stripes can be avoided. Further, by setting the contact force within the above range, the toner can be supplied to the developing roller without being deformed or crushed.

  The toner replenishment auxiliary member is for stably supplying toner to the developing roller. As the toner replenishing auxiliary member, for example, a water wheel-like roller with a stirring blade or a sponge-like roller is used. The size (diameter) of the toner replenishing auxiliary member is preferably 0.2 to 1.5 times the diameter of the developing roller. When the toner replenishing auxiliary member is within this range, the toner is supplied to the developing roller without excess or deficiency, and there is no image defect. Enables good image formation.

  Examples of the image carrier used in the image forming method according to the present invention include inorganic photoreceptors, amorphous silicon photoreceptors, and organic photoreceptors. Among these, organic photoreceptors are particularly preferable, and charge transport is further performed. A layered structure of a layer and a charge generation layer is preferred.

  Hereinafter, a developing device (developing device) that can be used in the image forming method according to the present invention will be described in detail.

  FIG. 3 is an external view (a) showing an example of the developing device 20 on which the developing roller according to the present invention can be mounted, and a schematic view (b) showing an example of a cross-sectional configuration.

  The developing device 20 shown in FIG. 3 is usually called a toner cartridge, and is formed on an image carrier with nonmagnetic one-component toner (nonmagnetic one-component developer) that is loaded and stored in the image forming apparatus. It is possible to develop the latent image. The developing device 20 includes the developing roller 10 according to the present invention, a buffer chamber 22 provided on the left side of the developing roller 10, and a hopper 23 adjacent to the buffer chamber 22. The developing roller 10 is rotationally driven in a counterclockwise direction in the drawing by a motor (not shown), and contacts or approaches an image carrier that is incorporated in an image forming apparatus (not shown).

  In the buffer chamber 22, a blade 24 as a toner regulating member is disposed in pressure contact with the developing roller 10. The blade 24 regulates the charge amount and adhesion amount of toner on the developing roller 10. Further, it is possible to further provide an auxiliary blade 25 for assisting the regulation of the toner charge amount and adhesion amount on the developing roller 10 on the downstream side of the blade 24 with respect to the rotation direction of the developing roller 10.

  A supply roller 26 is pressed against the developing roller 10. The supply roller 26 is rotationally driven in the same direction as the developing roller 10 (counterclockwise direction in the figure) by a motor (not shown). The supply roller 26 has a conductive cylindrical substrate and a foam layer formed of urethane foam or the like on the outer periphery of the substrate.

  The hopper 23 contains toner T which is a one-component developer. The hopper 23 is provided with a rotating body 27 for stirring the toner T. A film-like conveying blade is attached to the rotating body 27, and the toner T is conveyed by the rotation of the rotating body 27 in the direction of the arrow. The toner T conveyed by the conveying blades is supplied to the buffer chamber 22 through a passage 28 provided in a partition wall that separates the hopper 23 and the buffer chamber 22. The shape of the conveying blade is bent while the toner T is conveyed in front of the rotation direction of the blade 27 as the rotating body 27 rotates, and returns to a straight state when the left end of the passage 28 is reached. Thus, the blade T supplies the toner T to the passage 28 by returning the shape straight after passing through the curved state.

  The passage 28 is provided with a valve 321 for closing the passage 28. This valve is a film-like member, one end of which is fixed to the upper side of the right side of the passage 28 of the partition wall. When the toner T is supplied from the hopper 23 to the passage 28, the valve 28 is pushed rightward by the pressing force from the toner T. Can be opened. As a result, the toner T is supplied into the buffer chamber 22.

  A restricting member 322 is attached to the other end of the valve 281. The regulating member 322 and the supply roller 26 are arranged so as to form a slight gap even when the valve 321 closes the passage 28. The regulating member 322 adjusts so that the amount of toner accumulated at the bottom of the buffer chamber 22 does not become excessive, so that a large amount of toner T collected from the developing roller 10 to the supply roller 26 does not fall to the bottom of the buffer chamber 22. Adjusted to

  In the developing device 20, the developing roller 10 is rotationally driven in the direction of the arrow during image formation, and the toner in the buffer chamber 22 is supplied onto the developing roller 10 by the rotation of the supply roller 26. The toner T supplied onto the developing roller 10 is charged and thinned by a blade 24 and an auxiliary blade 25, and then conveyed to a region facing the image carrier to develop an electrostatic latent image on the image carrier. To be served. The toner that has not been used for development returns to the buffer chamber 22 as the developing roller 10 rotates, and is scraped and collected from the developing roller 10 by the supply roller 26.

  The developing bias power supply 29 provided in the developing device 20 forms an alternating electric field (for example, Vpp is 2.0 kV, frequency 2 kHz) with a DC voltage power source that outputs a set value (for example, about 500 V) of the developing bias voltage Vb. It consists of an AC power supply. “Vpp” indicates a peak-to-peak voltage that is the difference between the peak and valley of the amplitude of the alternating voltage waveform.

  At the time of image formation, the electrostatic latent image carrier is uniformly charged to a potential of, for example, about 800 V by a charging device (not shown), and then a predetermined portion is exposed by an optical head such as a laser. An electrostatic latent image is formed by being attenuated to a certain potential.

  In the developing region, the toner formed in a thin layer on the developing roller 10 flies from the circumferential surface of the developing roller 10 by the action of an electric field formed by the developing bias voltage Vb applied from the developing bias power supply device 29 and an alternating voltage. To become a cloud cloud. Then, toner is supplied onto the electrostatic latent image carrier on which the electrostatic latent image is formed, and the electrostatic latent image is developed to form a toner image.

  The thickness of the toner layer formed on the developing roller 10 is, for example, that the peripheral speed of the electrostatic latent image carrier 15 is 100 mm / sec, the peripheral speed of the developing roller 10 is 200 mm / sec, and the toner regulating member 24 is the developing roller. When the pressing force for pressing 10 is 10 to 100 N / m, the thickness can be about 1.5 layers (about 1.5 toner particles).

  The configuration of the developing device on which the developing roller according to the present invention can be mounted is not limited to the toner cartridge shown in FIG.

  Next, FIG. 4 shows an example of a full-color image forming apparatus in which the developing device 20 shown in FIG. 3 can be mounted, that is, a toner image can be formed using the developing roller according to the present invention. Note that the image forming apparatus on which the developing device 20 shown in FIG. 3 can be mounted is not limited to that shown in FIG.

  In the image forming apparatus shown in FIG. 4, a charging device 16 for uniformly charging the surface of the photosensitive drum 15 to a predetermined potential and a cleaner 17 for removing residual toner on the photosensitive drum 15 are provided around the photosensitive drum 15 that is rotationally driven. Is provided.

  The laser scanning optical system 18 scans and exposes the photosensitive drum 15 uniformly charged by the charging device 16 to form an electrostatic latent image on the photosensitive drum 15. The laser scanning optical system 18 includes a laser diode, a polygon mirror, and an fθ optical element, and print data for each of yellow, magenta, cyan, and black is transferred from the host computer to the control unit. Based on the print data of each color, a laser beam is sequentially output, and the photosensitive drum 15 is scanned and exposed to form an electrostatic latent image for each color.

  The developing device unit 30 containing the developing device 20 according to the present invention performs development by supplying each color toner to the photosensitive drum 15 on which the electrostatic latent image is formed. The developing device unit 30 is provided with four developing devices 20Y, 20M, 20C, and 20Bk each containing non-magnetic one-component toners of yellow, magenta, cyan, and black around the support shaft 33. Rotating to the center, each developing device 20 is guided to a position facing the photosensitive drum 15.

  The developing device unit 30 rotates around the support shaft 33 each time an electrostatic latent image of each color is formed on the photosensitive drum 15 by the laser scanning optical system 18 and stores the corresponding color toner. 20 is guided to a position facing the photosensitive drum 15. Then, each of the developing devices 20Y, 20M, 20C, and 20Bk sequentially supplies the charged color toners onto the photosensitive drum 15 to perform development.

  In the image forming apparatus of FIG. 4, an endless intermediate transfer belt 40 is provided downstream of the developing unit 30 in the rotation direction of the photosensitive drum 15, and is driven to rotate in synchronization with the photosensitive drum 15. The intermediate transfer belt 40 comes into contact with the photosensitive drum 15 at a portion pressed by the primary transfer roller 41 and transfers the toner image formed on the photosensitive drum 15. Further, a secondary transfer roller 43 is rotatably provided so as to face the support roller 42 that supports the intermediate transfer belt 40, and the portion on the intermediate transfer belt 40 is opposed to the support roller 42 and the secondary transfer roller 43. The toner image is pressed and transferred onto the recording material S such as recording paper.

  A cleaner 50 that removes residual toner on the intermediate transfer belt 40 is provided between the developing device unit 30 and the intermediate transfer belt 40 so as to be able to contact and separate from the intermediate transfer belt 40.

  A paper feeding unit 60 that guides the recording material S to the intermediate transfer belt 40 includes a paper feeding tray 61 that houses the recording material S, and a paper feeding roller 62 that feeds the recording material S stored in the paper feeding tray 61 one by one. It comprises a timing roller 63 that feeds the fed recording material S to the secondary transfer site.

  The recording material S on which the toner image is pressed and transferred is conveyed to the fixing device 70 by a conveying means 66 constituted by an air suction belt or the like, and the toner image transferred by the fixing device 70 is fixed on the recording material S. After fixing, the recording material S is transported through the vertical transport path 80 and discharged onto the upper surface of the apparatus main body 100.

Examples of the present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.
1. Production of Developing Rollers “Developing rollers 1 to 11” were produced by the following procedure.
(1) Production of developing roller 1 A resin layer forming solution (coating solution) obtained by mixing and dispersing the following materials was produced.

Urethane resin “Nipporan 5120 (manufactured by Nippon Polyurethane)” 100 parts by mass Furnace black 20 parts by mass Methyl ethyl ketone (MEK) 400 parts by mass Cross-linked polyurethane resin particles having an average primary particle size of 10 μm 50 parts by mass This coating solution is made of SUS303 having a diameter of 10 mm. A coating layer having a thickness of 15 μm was applied to the peripheral surface of the shaft, and a heat treatment at 100 ° C. was performed for 1 hour to form a resin layer, whereby “developing roller 1” was produced.
(2) Production of developing roller 2 In the production of “Developing roller 1”, “Developing” was performed in the same procedure except that the addition amount of crosslinked polyurethane resin particles having an average primary particle size of 10 μm in the coating solution was changed to 40 parts by mass. Roller 2 "was produced.
(3) Production of developing roller 3 In the production of “Developing roller 1”, “Development” was performed in the same procedure except that the addition amount of crosslinked polyurethane resin particles having an average primary particle size of 10 μm in the coating solution was changed to 30 parts by mass. Roller 3 "was produced.
(4) Production of developing roller 4 In production of “developing roller 2”, the crosslinked polyurethane resin particles having an average primary particle size of 10 μm added to the coating solution were changed to crosslinked acrylic resin particles having an average primary particle size of 20 μm. Other than that, “developing roller 4” was prepared in the same procedure.
(5) Production of developing roller 5 In the production of “developing roller 4”, the procedure was the same except that the addition amount of crosslinked acrylic resin particles having an average primary particle size of 20 μm added to the coating solution was changed to 30 parts by mass. “Developing roller 5” was produced.
(6) Production of developing roller 6 In the production of “developing roller 4”, the procedure was the same except that the addition amount of crosslinked acrylic resin particles having an average primary particle size of 20 μm added to the coating solution was changed to 20 parts by mass. “Developing roller 6” was produced.
(7) Production of developing roller 7 In production of “developing roller 2”, the crosslinked polyurethane resin particles having an average primary particle size of 10 μm added to the coating liquid were changed to crosslinked polyurethane resin particles having an average primary particle size of 30 μm. Other than that, “Developing roller 7” was prepared in the same procedure.
(8) Production of developing roller 8 In the production of “developing roller 7”, the procedure was the same except that the addition amount of the crosslinked polyurethane resin particles having an average primary particle size of 30 μm added to the coating solution was changed to 30 parts by mass. “Developing roller 8” was produced.
(9) Production of developing roller 9 In the production of “Developing roller 7”, the procedure was the same except that the addition amount of the crosslinked polyurethane resin particles having an average primary particle size of 30 μm added to the coating liquid was changed to 20 parts by mass. “Developing roller 9” was produced.
(10) Production of developing roller 10 After producing “Developing roller 4”, 100 parts by mass of urethane resin “Nippolan 5120 (manufactured by Nippon Polyurethane)” and 20 parts by mass of furnace black were mixed and dispersed in 400 parts by mass of methyl ethyl ketone. The coating solution was applied on the above resin layer so as to have a thickness of 5 μm. After the application, heat treatment at 100 ° C. was performed for 40 minutes to form a second resin layer, which was designated as “developing roller 10”.
(11) Production of Development Roller 11 After production of “Development Roller 8”, 100 parts by mass of urethane resin “Nipporan 5120 (manufactured by Nippon Polyurethane)” and 20 parts by mass of furnace black were mixed and dispersed in 400 parts by mass of methyl ethyl ketone. The coating solution was applied on the above resin layer so as to have a thickness of 5 μm. After coating, a heat treatment at 100 ° C. was performed for 40 minutes to form a second resin layer, which was designated as “developing roller 11”.

  Table 1 shows the roughness imparted inter-particle spacing Sm and the average centerline roughness Ra of the produced “developing rollers 1 to 11”.

2. Preparation of toner (1) Preparation of “resin particle dispersion 1” In a flask equipped with a stirrer, 72.0 parts by mass of pentaerythritol tetrastearate, 115.1 parts by mass of styrene, 42.0 n-butyl acrylate It added to the monomer liquid mixture which consists of 10.9 mass parts of mass parts and methacrylic acid, and it heated and dissolved at 80 degreeC.

  On the other hand, 7.08 parts by mass of an anionic surfactant (sodium dodecylbenzenesulfonate: SDS) was dissolved in 2760 parts by mass of ion-exchanged water in a separable flask equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction apparatus. The surfactant solution thus prepared was added, and the temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. Next, the monomer solution (80 ° C.) is mixed and dispersed in the surfactant solution (80 ° C.) by a mechanical disperser “CLEARMIX (M Technique Co., Ltd.)” having a circulation path, An emulsified liquid in which emulsified particles (oil droplets) having a uniform dispersed particle diameter were dispersed was prepared.

An initiator solution in which 0.84 parts by mass of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 parts by mass of ion-exchanged water was added to this dispersion, and this system was heated at 80 ° C. for 3 hours. The polymerization reaction was carried out with stirring. A solution prepared by dissolving 7.73 parts by mass of a polymerization initiator (KPS) in 240 parts by mass of ion-exchanged water was added to the obtained reaction solution. After 15 minutes, the temperature was adjusted to 80 ° C., and then 383.6 masses of styrene. Part mixture, 140.0 parts by mass of n-butyl acrylate, 36.4 parts by mass of methacrylic acid, and 12 parts by mass of n-octyl mercaptan was added dropwise over 100 minutes, and the system was added at 80 ° C for 60 minutes. After heating and stirring, the system was cooled to 40 ° C. to prepare a resin particle dispersion containing wax (hereinafter referred to as “latex (1)”).
(2) Preparation of “Colorant Dispersion Liquid K” On the other hand, 9.2 parts by mass of sodium n-dodecyl sulfate was stirred and dissolved in 160 parts by mass of ion-exchanged water. While stirring this solution, 20 parts by mass of carbon black “Mogal L” (Cabot Corp.) was gradually added as a colorant, and then a mechanical disperser “Claremix” (M Technique Co., Ltd.) was added. Using the dispersion treatment, “Colorant Dispersion Liquid K” was prepared. When the particle diameter of the colorant particles in “Colorant Dispersion Liquid K” was measured with an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 120 nm.
(3) Production of “colored particles 1” In a reaction vessel (four-necked flask) equipped with a temperature sensor, a cooling pipe, a stirring device (having two stirring blades, an intersection angle of 20 °), and a shape monitoring device, 1250 parts by mass of “resin particle dispersion 1” (in terms of solid content), 2000 parts by mass of ion-exchanged water, and the total amount of “colorant dispersion 1” were adjusted to an internal temperature of 25 ° C. The pH was adjusted to 10.0 by adding 5 mol / liter aqueous sodium hydroxide solution. Next, an aqueous solution in which 52.6 parts by mass of magnesium chloride hexahydrate was dissolved in 72 parts by mass of ion-exchanged water was added over 10 minutes at 25 ° C. with stirring. Thereafter, the temperature increase was started immediately, and this system was heated to 95 ° C. over 5 minutes (temperature increase rate: 14 ° C./min).

  In this state, the particle size of the aggregated particles was measured with “Multisizer 3 (manufactured by Beckman Coulter)”. When the volume-based median diameter (D50) reached 6.5 μm, 115 parts by mass of sodium chloride was ionized. Particle growth was stopped by adding an aqueous solution dissolved in 700 parts by mass of exchange water. Furthermore, after heating and stirring for 8 hours at a liquid temperature of 90 ° C. (stirring rotation speed: 120 rpm) and continuing aging, the system was cooled to 30 ° C. at 10 ° C./min. The pH was adjusted to 3.0 by addition and stirring was stopped.

The produced particles are filtered, washed repeatedly with ion-exchanged water, classified in liquid with a centrifugal separator, and then dried using a flash jet dryer to give “colored particles 1” having a water content of 1.0 mass%. Was generated.
(4) Production of colored particles 2 and 3 In the production process of “colored particles 1”, when the volume-based median diameter of the aggregated particles is 8.0 μm in “Multisizer 3 (manufactured by Beckman Coulter)”, the sodium chloride An aqueous solution was added to stop the particle growth, and “Colored Particle 2” was produced. In addition, when the volume-based median diameter of the aggregated particles is 5.0 μm in “Multisizer 3 (manufactured by Beckman Coulter)”, the sodium chloride aqueous solution is added to stop the particle growth, and “colored particles 3” Produced.
(5) Preparation of “Toners 1 to 3” The above-mentioned “colored particles 1 to 3” are subjected to the following external addition treatment, whereby non-magnetic ones having a volume-based median diameter of 6.5 μm, 8.0 μm, and 5.0 μm. Component toners “Toners 1 to 3” were prepared. That is, 0.8 parts by mass of hydrophobic silica having a number average primary particle diameter of 12 nm and a hydrophobization degree of 65, and 0.5 parts by mass of hydrophobic titania having a number average primary particle diameter of 30 nm and a hydrophobization degree of 55 are added. Then, the mixture was processed with a Henschel mixer.

  Table 2 shows the volume-based median diameter R, the value of the spacing Sm (μm) between the roughness-imparting particles, and the value of the average center line roughness Ra (μm) of the produced “Toners 1 to 3”. .

A developing device is prepared by combining the “toners 1 to 3” produced in this way and the aforementioned “developing rollers 1 to 11” as shown in Table 3 to be described later, and “Examples 1 to 13” and “ It was set as Comparative Examples 1 to 12. And about these, the evaluation experiment shown below was conducted.
3. Evaluation Experiment The above-mentioned “Examples 1 to 13” and “Comparative Examples 1 to 12” are configured in a commercially available color laser printer “Magicor 5440DL (manufactured by Konica Minolta Business Technology Co., Ltd.)” employing a non-magnetic one-component development system. A developing device is installed.

  Evaluation was performed by producing a print on a black image. That is, the image forming performance was evaluated by carrying out continuous printing of 3000 sheets under a normal temperature and humidity environment (20 ° C., 50% RH). Note that continuous printing outputs an original image with a pixel rate of 6% (A4 size original image with halftone image, portrait photo, solid white image, solid image divided into 1/4 each), and a predetermined number of sheets Evaluation was performed using printed materials in the eyes.

  The evaluation was performed for “fogging”, “creaking and chipping”, “visual observation of the developing roller surface”, “image density fluctuation”, and “image density unevenness” as shown below.

<Fog>
An evaluation was made on fogging that appears to be caused by the occurrence of toner adhesion to the surface of the developing roller. In the evaluation of fog, an image having a reflection density (fogging density) of a white background portion on a printed image prepared after continuous printing of 3000 sheets was less than 0.01 was regarded as acceptable. The reflection density measurement of the white background portion was performed using a reflection densitometer “RD-918 (manufactured by Macbeth)”.

<Crushing / Deficit>
As evaluation of toner transportability on the surface of the developing roller, occurrence of close-up and chipping in solid images and halftone images was evaluated. In the evaluation, the solid image and the halftone image are visually evaluated for the presence or absence of a lightly darkened portion (= chip) or a darkened portion (= creeping) on the leading and trailing edges in the paper conveyance direction (limit sample). Sample).

  If there was no chipping or rushing, it was judged as “good”, and if any one was present, it was judged as “poor”.

<Visual observation of developing roller surface>
After 3000 sheets were continuously printed, the surface of the developing roller was visually observed using a magnifying glass having a magnification of 10 times, and the presence or absence of filming was evaluated by observing the state of toner adhesion on the surface of the developing roller.

<Image density fluctuation>
The density variation in the solid image portion on the evaluation image output at the start and at the end of continuous printing of 3000 sheets was evaluated. Select any 10 points on the solid image area, measure the reflection density using a Macbeth reflection densitometer (RD-918), and remove the 8 points from which the density is maximum and minimum. The average concentration was calculated from the concentration. The difference between the average densities at the start and end of continuous printing calculated in this way was obtained, and this was used as the image density fluctuation. An image density difference of less than 0.15 was accepted.

<Image density unevenness>
The evaluation was performed on the halftone image portion and the solid black image portion on the evaluation image output after the printing of 3000 sheets. Select any 10 points on each image area, measure the reflection density using a Macbeth reflection densitometer (RD-918), find the maximum density and the minimum density, and find the density difference as an image density unevenness. As evaluated. A case where the density difference in the halftone image area was 0.05 or less and the density difference in the solid image area was 0.15 or less was accepted.

  The results are shown in Table 3.

  As shown in Table 3, in Examples 1 to 13 that satisfy the structural requirements of the present invention, it is determined that toner adhesion on the surface of the developing roller has not occurred. In Examples 1 to 13, no image defect, which was caused by a charging defect such as an image defect, density fluctuation, or density unevenness, was observed on the produced toner images. Further, no rushing or chipping is observed on the toner image, and it is determined that the toner is smoothly conveyed on the developing roller.

  On the other hand, Comparative Examples 1 to 12 that do not satisfy the constituent requirements of the present invention do not satisfy any of the above evaluation results, and toner adhesion or charging failure occurs on the surface of the developing roller. Judged to be.

  As is apparent from the results in Table 3, according to the present invention, in the developing roller using the roughness imparting particles, the toner transportability and charging performance may be closely related to the toner used. confirmed.

It is a cross-sectional block diagram of what corresponds to the developing roller which concerns on this invention. FIG. 5 is a schematic diagram for explaining a roughness imparting inter-particle spacing Sm and an average center line roughness Ra on the developing roller surface. FIG. 2 is a schematic diagram illustrating an example of a developing device on which a developing roller according to the present invention can be mounted. 1 is a schematic view of an image forming apparatus in which a developing roller according to the present invention can be used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Developing roller 11 Shaft 12 Resin layer 13 Roughness imparting particle 15 Photosensitive drum (image carrier)
20 Developing device (toner cartridge)
30 Developing Device 40 Intermediate Transfer Belt 60 Paper Feeding Unit 70 Fixing Device S Recording Material T Toner

Claims (2)

A toner is carried on the surface of a developing roller having a conductive resin layer on the outer periphery of a conductive shaft, and the carried toner is supplied onto the image carrier to develop the electrostatic latent image on the image carrier with non-magnetic one-component development. In an image forming method having a step of developing by a method,
A developing roller for supplying toner onto the image carrier;
Containing roughness imparting particles that impart roughness to the developing roller surface in the resin layer,
The spacing between the roughness-imparting particles in the resin layer is Sm (μm), the average center line roughness of the resin layer is Ra (μm), and the volume-based median diameter of the toner carried on the resin layer surface is R (μm). )
10R ≦ Sm ≦ 30R
R / 5 ≦ Ra ≦ R / 2
An image forming method having the following relationship: A toner is carried on the surface of a developing roller having a conductive resin layer on the outer periphery of a conductive shaft, and the carried toner is supplied onto the image carrier to develop the electrostatic latent image on the image carrier with non-magnetic one-component development. In an image forming apparatus having a developing means for developing by a method ,
A developing roller for supplying toner onto the image carrier;
Containing roughness imparting particles that impart roughness to the developing roller surface in the resin layer,
The spacing between the roughness-imparting particles in the resin layer is Sm (μm), the average center line roughness of the resin layer is Ra (μm), and the volume-based median diameter of the toner carried on the resin layer surface is R (μm). )
10R ≦ Sm ≦ 30R
R / 5 ≦ Ra ≦ R / 2
An image forming apparatus having the following relationship:

Images