JPH0815979A - Image forming method - Google Patents

Abstract

PURPOSE:To provide an image forming method by which toner is excellently carried even when globular toner is used and further toner component is prevented from melt sticking on the surface of a developer carrier. CONSTITUTION:In this image forming method, developer 41 carried on the developer carrier is.carried to a developing area and an electrostatic latent image formed on an image carrier 1 is developed in a developing area with the developer 41 to form a toner image on the image carrier; and the developer 41 contains toner having toner particles which contains 5-30 wt.% low softening point compound and whose shape factor SF-1 is 100 to 130, and the surface for carrying the developer 41 of the developer carrier 21 satisfies a condition of 0.2mum <= center line average roughness (Ra)<=5.0mum, 10mum <= average interval(Sm) between recessed and projected parts <= 80mum, and 0.05<=Ra/Sm<=0.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method using electrophotography. More specifically, the present invention relates to an image forming method used for forming an image on a copying machine, a printer, a fax machine or the like, which develops an electrostatic latent image by using a toner having a spherical shape.

[0002]

2. Description of the Related Art Conventionally, a toner using an electrophotographic process is prepared by adding a colorant, a charge control agent and a release agent to a polyester resin, a styrene-acrylic resin, an epoxy resin, etc., melt-kneading them, and uniformly dispersing Generally, a production method by a pulverization-classification method in which pulverization is performed to a predetermined particle size and excess fine / coarse powder is removed using a classifier is generally used. However, it has become necessary to further reduce the particle size of the toner as the image quality is further improved in recent years. As the average particle diameter of the toner measured by a Coulter counter becomes 7 μm or less, it is possible to classify the toner into a uniform dispersibility and highly efficient pulverizability of raw materials used, and a sharp particle size distribution, which has not been a problem in the past. It tends to be extremely difficult.

In order to overcome the problems of toner by the pulverization-classification method, Japanese Patent Publication Nos. 36-10231 and 43.
No. 10799 and Japanese Patent Publication No. 51-14895 propose a method for producing a toner by a suspension polymerization method. In the suspension polymerization method, a polymerizable monomer, a colorant, a polymerization initiator and, if necessary, a crosslinking agent, a charge control agent, and other additives are uniformly dissolved or dispersed to obtain a monomer composition. Then, the monomer composition is dispersed in a continuous phase (for example, an aqueous phase) containing a dispersion stabilizer by using a suitable stirrer,
In this method, a polymerization reaction is simultaneously performed to obtain a toner having a desired particle size. This manufacturing method does not need to impart brittleness to the toner because it does not go through a crushing step, and can further use a large amount of a low softening point substance that could not be used in the conventional crushing method. The width can be increased. This manufacturing method is characterized in that the hydrophobic release agent, colorant, etc. are not easily exposed on the surface of the toner particles, so that the developer holding member, the photoconductor, the transfer roller, the fixing device, etc. are less contaminated. are doing.

Further, in recent years, digital full-color copying machines and printers have been put into practical use, and toners excellent in color reproducibility without color unevenness as well as resolution and gradation are desired. In a digital full-color machine, after color image development is separated with B (blue), G (green), and R (red) filters, 20 μm to 7 corresponding to the original image
A latent image consisting of a dot diameter of 0 μm is Y (yellow), M
(Magenta), C (cyan), and B (black) toners are used for development, but it is necessary to transfer a larger amount of toner from the photoconductor to the transfer material than in a black-and-white copying machine, and further in the future. It is expected that there will be a demand for a finer toner particle size corresponding to finer dots in order to achieve higher image quality. With the speeding up and full-colorization of future printers and copiers,
Further improvement in low temperature fixability is also important. From this point as well, a polymerization method capable of producing a toner having a sharp particle size distribution and a minute particle size and encapsulating a low softening point compound in the toner particles is
It is advantageous.

The color toners mounted on the full-color copying machine are required to be sufficiently mixed with multicolor toners in the fixing step, which is important for improving color reproducibility and transparency of OHP images. Compared to black toner, color toner is
In order to enhance the color mixing property, it is generally desired that the resin is formed of a sharp melt low molecular weight resin. For a general black toner, a release agent having relatively high crystallinity and low transparency such as polyethylene wax or polypropylene wax is used in order to improve high temperature offset property at the time of fixing. However, in the color toner for full color, the crystallinity of this release agent is high, and therefore, when a color image is formed on the film on the OHP, the transparency is significantly impaired. Therefore, by normally applying the silicone oil to the heat fixing roller without adding a releasing agent as a constituent of the color toner, the high temperature offset resistance is improved. However, the transfer material having a fixed image obtained in this manner is apt to cause discomfort when used by the user, since excess silicone oil tends to adhere to the surface thereof.

For this reason, a toner for oilless fixing in which a large amount of a substance having a low softening point is contained in the toner particles has been studied, but it has excellent low-temperature fixing property and transparency, and at the same time has high-temperature offset resistance. There is a long-awaited need for superior toner.

Conventionally, a toner prepared by the direct polymerization method is supported on a developer carrier by using a two-component developer having a carrier or a one-component developer having no toner prepared by the direct polymerization method (without a carrier). After that, in the method of developing the electrostatic latent image, transferring the toner image to the transfer material, and then fixing the toner image on the transfer material, a proper uniform developer is usually used by using a regulating member on the developer carrier. It is necessary to form layers.

However, when the toner obtained by the direct polymerization method is used in the developing device which constitutes such a developer regulating member, the toner obtained by the direct polymerization method is extremely superior to the toner obtained by the pulverization method. Since the fluidity is good, a phenomenon may occur in which the toner slips between the developer carrying member and the regulating member. Therefore, the charge amount between the toner particles is likely to be non-uniform, and as a result of not being able to obtain a uniform coating, a background image may be generated or a defective image with image unevenness may occur. Further, when the surface of the developer carrier is mirror-like and smooth, the toner is unevenly distributed to both ends of the developer carrier due to insufficient conveying force in the circumferential direction, and the toner is left on the bearings in the repeated durability image output test. It is easy for the toner to enter, a fused substance of the toner is likely to be generated, and a transfer failure is likely to occur at the time of transfer.

In general, a toner using direct polymerization is substantially spherical and therefore is likely to be most densely packed in the developing device. In some cases, the toner is densely packed in a downstream portion of the regulating member in the developing device. Since the toner is filled, the mechanical load on the toner is increased, and the sleeve is liable to be contaminated due to the fusion of the toner on the developer carrying member. Sleeve contamination is not preferable because it causes a decrease in image density and causes fog on the ground. This phenomenon becomes more remarkable in the toner by the polymerization method containing a large amount of the low softening point substance.

A toner prepared by a direct polymerization method from a monomer composition containing 50 to 3000 parts by weight of a low softening point substance such as paraffin wax is disclosed in Japanese Patent Application Laid-Open No. 63-247762. Proposals have been made that focus on the surface roughness (Rzmax value) of the developer carrier. However, regarding the fusing of the toner onto the developer carrying member, an effect was recognized in the initial stage in repeated image development durability, but a low softening point substance in the toner particles of 50 to 3 was used.
The toner obtained by the direct polymerization method containing 000 parts by weight is
After the repeated image formation and durability, fusion of the toner component was observed on the developer carrying member. Surface roughness of developing sleeve (Rzm
It has been difficult to stably convey a toner having good fluidity by the developer carrying member only by restricting only the ax value).

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method which solves the above problems.

An object of the present invention is to provide an image forming method capable of obtaining an image having excellent image quality and fixability without causing image density unevenness and fog even when continuously durable.

An object of the present invention is to provide an image forming method capable of obtaining a stable image without causing toner fusion on the developer carrying member.

[0014]

SUMMARY OF THE INVENTION The present invention conveys a developer carried on a developer carrying member to a developing area and develops the electrostatic latent image formed on the image carrying member in the developing area. In an image forming method of developing with a developer to form a toner image on an image bearing member, the developer is a toner particle containing 5 to 30% by weight of a low softening point compound and having a shape factor SF-1 of 100 to 130. The surface of the developer carrying member for carrying the developer has the following condition 0.2 μm ≧ center line average roughness (Ra) ≦ 5.0 μm 10 μm ≦ concavo-convex average spacing (Sm) ≦ The present invention relates to an image forming method characterized by satisfying 80 μm 0.05 ≦ Ra / Sm ≦ 0.5.

In the present invention, the toner shape factor SF-1
The toner having a value of 100 to 130 exhibits good fluidity.
In the case of a toner having an aggregation degree of 30% or less, which is one index of fluidity, and more preferably 3 to 25%, transfer from a photoreceptor, which is a carrier of an electrostatic latent image, onto an intermediate transfer body or a transfer material. The efficiency is extremely high, and a high transfer efficiency of 93% or more is possible. Even if the toner has a shape factor SF-1 of 100 to 130, if the fluidity of the developer obtained by mixing the toner and the additive having extremely poor fluidity exceeds 30%, the transfer efficiency of There was a decline. On the other hand, when the cohesion is less than 3%, the transfer efficiency shows an excellent value, but conversely, the phenomenon of toner agent scattering around the image is unfavorable. As described above, the toner having the shape factor SF-1 of 100 to 130 has a great effect particularly in the transfer step of the electrophotographic process. It is easy to slip through the regulation member and to cause uneven unevenness on the developer carrying member, and it is difficult to continue high-quality images.

In the present invention, the toner contains 5 to 30% by weight of a low softening point substance in order to exhibit low-temperature fixability, so that the resistance of the toner to the external force such as slippage is likely to be extremely lowered. Further, since the toner has a substantially spherical shape, the toner has excellent fluidity, but the toner contains a compound having a low softening point of 5 to 30% by weight and is easily deformed. It is necessary to uniformly coat the toner on the developer carrier without giving the above-mentioned load.

The developer carrier used in the present invention has the following conditions: 0.2 μm ≦ center line average roughness (Ra) ≦ 5.0 μm 10 μm ≦ unevenness average interval (Sm) ≦ 80 μm 0.05 ≦ Ra / Sm ≦ It satisfies 0.5.

Ra and Sm are JIS B 0601.
And a value that defines the average roughness of the center line and the average interval of the unevenness described in ISO468 and is calculated by the following formula (see FIG. 1).
reference).

[0019]

[Outside 1]

When Ra is less than 0.2 μm, the transportability with respect to the toner is insufficient, so that density unevenness due to durability and image density unevenness are likely to occur. When Ra exceeds 5 μm, although the ability to convey toner is excellent, the regulating force in the developer conveyance amount regulating portion such as the regulating blade becomes too large, so that the external additive on the surface of the toner particles is deteriorated by rubbing and becomes durable. The image quality at that time tends to deteriorate.

If Sm is more than 80 μm, it becomes difficult for the toner to be held on the developer carrying member, so that the image density becomes low. The cause of this is unknown in detail, but because the developer carrying member and the toner are slipping at the conveyance amount regulating portion of the developer carrying member, if the unevenness becomes too wide, the toner will be densely packed. It is thought that the force acts as a lump and the force exceeds the holding force between the developer bearing member and the toner, and thus the image density is lowered. When Sm is less than 10 μm, most of the irregularities on the surface of the developer carrying member are smaller than the average particle diameter of the toner, so that the toner entering the recesses has particle size selectivity, and fusion due to the fine powder component of the toner easily occurs. Also, it is not easy to manufacture the developer carrying member.

From the above viewpoint, the slope of the convex / concave (≉f) obtained from the height of the convex on the developer carrying member and the interval between the concaves and convexes.
(Ra / Sm)) is also important. In the present invention, it is necessary that 0.5 ≧ Ra / Sm ≧ 0.05, and more preferably 0.07 or more and 0.3 or less.

When Ra / Sm is less than 0.05, the toner holding force on the developer carrying member is weak and it becomes difficult for the toner to be held on the developer carrying member. As a result, uneven image density is likely to occur.
If Ra / Sm exceeds 0.5, the toner that has entered the concave portions on the surface of the developer carrying member becomes difficult to circulate with other toners, so that toner fusion easily occurs.

By processing several grooves (so-called knurls) in the lengthwise direction of the developer carrier, it becomes easier to evenly coat the toner having excellent fluidity on the developer carrier. .

At present, there is a strong demand for reducing the particle size of the toner in order to improve the image quality of the image, and the particle size distribution of the toner measured by a Coulter counter is 4 to 8 μm in weight average diameter, and the number distribution of toner is The coefficient of number variation based on
For toner of 5% or less, it is extremely important to strictly control the roughness of the surface of the developer carrier. When the weight average particle diameter of the toner is 4 to 8 μm, when the toner manufacturing method by the pulverization method is used, ultrafine powder is inevitably produced as a by-product, and it is difficult to remove the ultrafine powder even if the classification step is used. Or Even when the direct polymerization method is used, if the number variation coefficient is not less than 35%, even if the surface roughness of the developer carrier is regulated, ultrafine powder is likely to be accumulated in the recesses, resulting in contamination of the developer carrier, which is not preferable.

In the present invention, Ra and Sm are measured by using a contact type surface roughness measuring instrument SE-3300 (manufactured by Kosaka Laboratory Ltd.), and the measurement length l is 2. in accordance with JIS-B0601.
It was set to 5 mm, and the measurement was performed by measuring several points on the surface of the developer carrying member.

The method for producing a developer carrier having a predetermined surface roughness according to the present invention is, for example, a sand blast method using irregular particles or regular particles as abrasive grains, and sand having irregularities formed in the sleeve circumferential direction. A sandpaper method of rubbing the sleeve surface in the axial direction with paper, a method of chemical treatment, a method of forming resin protrusions after coating with resin, and the like can be used.

As the material of the developer carrying member in the present invention, known materials can be used. For example, metal such as aluminum, stainless steel, nickel; carbon, resin elastomer, etc. coated on the metal; elastic body such as natural rubber, silicone rubber, urethane rubber, neoprene rubber, butadiene rubber, chloroprene rubber, non-foamed body, Examples thereof include those processed in the form of foam or sponge, or those coated with carbon, resin elastomer or the like.

The shape of the developer carrying member in the present invention may be cylindrical or sheet.

When the developer carrying member is a cylindrical developing sleeve, the developing sleeve preferably has a diameter of 12 to 30 mm (more preferably 15 to 25 mm) from the viewpoint of developing efficiency and suppressing toner fusion. . When the toner is a magnetic toner or a two-component developer of a non-magnetic toner and a magnetic carrier, a magnetic field generating means such as a magnet is included inside the developer carrier.

In the present invention, SF-1 indicating the shape factor
Is, for example, Hitachi FE-SEM (S-800)
, A toner image magnified 500 times, for example,
Image data is sampled at random, and the image information is, for example, an image analysis device (Luz
exIII) is introduced and analyzed, and the value calculated by the following formula is defined as the shape factor SF-1.

[0032]

[Outside 2] [Wherein MXLNG represents the absolute maximum length of the toner particles,
AREA indicates the projected area of the toner particles. ]

When the shape factor SF-1 of the toner is larger than 130, the spherical shape gradually approaches the irregular shape, and at the same time, the transfer efficiency decreases.

In order to realize extremely high transferability, a substantially spherical toner having a toner shape factor SF-1 of 100 to 130, more preferably 100 to 120, is preferable, and it is more preferable for higher image quality. In order to faithfully develop minute latent image dots, the toner has a weight average diameter of 4 μm to 8 μm.
It is preferable that the coefficient of variation of number in m is 35% or less.
When the toner has a weight average diameter of less than 4 μm, a large amount of transfer residual toner is generated on the photosensitive member or the intermediate transfer member due to a decrease in transfer efficiency, which easily causes nonuniform image unevenness due to fog or transfer failure. When the weight average diameter of the toner exceeds 8 μm, the toner is apt to be fused to various members,
If the coefficient of variation of the number of toner exceeds 35%, this tendency becomes more serious and becomes a problem.

The low softening point compound used in the present invention is preferably a compound having a main body maximum peak value of 40 to 90 ° C. in an endothermic peak measured according to ASTM D3418-8. When the maximum peak is less than 40 ° C., the self-aggregating force of the low softening point substance is weakened, and as a result, the high temperature offset property is weakened, which is not preferable for a color toner for a full color developer. On the other hand, the maximum peak is 90 ° C
If it exceeds, the fixing temperature becomes high, and it becomes difficult to properly smooth the surface of the fixed image, which is not preferable in terms of color mixing. Further, when a toner is obtained by a direct polymerization method, the temperature of the maximum peak value is high because granulation and polymerization are carried out in an aqueous medium, so that a low softening point substance is mainly precipitated during granulation, which is not preferable.

For measuring the temperature of the maximum peak value of the low softening point compound, for example, DSC-7 manufactured by Perkin Elmer Co. is used. The melting point of indium and zinc is used to correct the temperature of the device detection unit, and the heat of fusion of indium is used to correct the amount of heat. For the sample, an aluminum pan was used and an empty pan was set as a control, and the temperature rising rate was 10 ° C./min. Measure with.

Examples of the low softening point compound include paraffin wax, polyolefin wax, Fischer-Tropish wax, amide wax, higher fatty acid, ester wax and derivatives thereof or graft / block compounds thereof. Preferably 10 carbon atoms
The ester wax having one or more long-chain hydrocarbon groups described above is particularly preferable in the present invention because it has an effect on the high temperature offset property without impairing the transparency of OHP. The structural formulas of typical compounds of the ester wax are shown below.

[0038]

[Outside 3] [In the formula, a and b represent an integer of 0 to 4, a + b is 4, R ₁ and R ₂ represent an organic group having 1 to 40 carbon atoms, and the number of carbon atoms of R ₁ and R ₂ is A group having a difference of 10 or more is shown, n and m are integers of 0 to 15, and n and m are not 0 at the same time. ]

[0039]

[Outside 4] Wherein, a and b is an integer of 0 to 4, a + b is 4, R ₁ represents an organic group having a carbon number of 1 to 40, n and m represents an integer of 0 to 15, n And m cannot be 0 at the same time. ]

[0040]

[Outside 5] [In the formula, a and b represent an integer of 0 to 3, a + b is 3 or less, R ₁ and R ₂ represent an organic group having 1 to 40 carbon atoms, and R ₁ and R ₂ are carbon atoms. R ₃ represents a group having a number difference of 10 or more, R ₃ represents an organic group having 1 or more carbon atoms, n and m represent integers of 0 to 15, and n and m do not become 0 at the same time. ]

Structural formula of ester wax R ₁ —COO—R ₂ [wherein, R ₁ and R ₂ represent a long-chain organic group having 15 to 45 carbon atoms]. ]

The ester wax preferably used in the present invention preferably has a hardness of 0.5 to 5.0.
The hardness of the ester wax is 20 mmφ in diameter and 5 in thickness.
It is a value obtained by measuring the Vickers hardness using, for example, a dynamic ultra-micro hardness meter (DUH-200) manufactured by Shimadzu Corporation after manufacturing a sample having a cylindrical shape of mm. The measurement conditions are
Vickers hardness is obtained by displacing 10 μm under a condition of a load rate of 9.67 mm / sec with a load of 0.5 g and holding it for 15 seconds, measuring the obtained dent shape. If the hardness is less than 0.5, the ester wax has a large dependency on the pressure and the process speed of the fixing device, and the high temperature offset effect is apt to be insufficiently expressed. On the other hand, if it exceeds 5.0, the storage stability of the toner becomes poor. Since the ester wax is scarce and the self-cohesive force of the ester wax itself is small, the high temperature offset tends to be insufficient. Specific compounds include the following compounds.

[0043]

[Outside 6]

[0044]

[Outside 7]

In recent years, the need for full-color double-sided images has been increasing, and when images are formed on both sides of a transfer material, the fixed image on the transfer material formed first on the front surface is then fixed on the back surface. Since the toner passes through the heating portion of the fixing device again when it is formed, it is necessary to sufficiently consider the high temperature offset property of the toner. Therefore, in the present invention, the low softening point compound is added to the toner particles in an amount of 5 to 30% by weight. If it is less than 5% by weight, the high temperature offset resistance tends to be lowered, and further, the image on the back side tends to show an offset phenomenon when fixing the double-sided image. If it exceeds 30% by weight, toner particles are likely to coalesce with each other during granulation in the production by the polymerization method, and particles having a wide particle size distribution are likely to be produced.

As a method for producing the toner used in the present invention, a resin, a release agent composed of a low softening point compound, a colorant, a charge control agent and the like are uniformly dispersed in a pressure kneader, an extruder or a media disperser. After dispersion, mechanically or in a jet stream, collide with a target to finely pulverize to a desired developer particle size, and then a pulverization-classification method toner particle that sharpens the particle size distribution through a classification step is required. Manufacturing method of spheroidizing by means of Japanese Patent Publication No. 56-1394
A method for obtaining spherical toner particles by atomizing a molten mixture in the air using a disk or a multi-fluid nozzle described in JP-A-5-53; JP-B-36-10231 and JP-A-59-53.
No. 856 and JP-A No. 59-61842, a method of directly producing toner particles by using a suspension polymerization method; an aqueous organic solvent in which a monomer-soluble polymer obtained is insoluble A dispersion polymerization method for directly producing toner particles using;
An emulsion polymerization method such as a soap-free polymerization method in which toner particles are directly polymerized in the presence of a water-soluble polar polymerization initiator can be used.

However, in the method of producing toner particles by the pulverization method, it is difficult to set SF-1 which is the shape factor of the developer measured by Luzex within the range of 100 to 130, and in the melt spray method. Is
Even if the SF-1 value can be set within a predetermined range, the obtained toner is likely to have a wide particle size distribution, and the manufacturing method is low in efficiency. On the other hand, in the dispersion polymerization method, the obtained toner shows an extremely sharp particle size distribution, but the selection of materials to be used is narrow and the use of organic solvents is not suitable for production equipment from the viewpoint of waste solvent treatment and solvent flammability. It is complicated and easily complicated. The emulsion polymerization method typified by soap-free polymerization is effective because the toner particle size distribution is relatively uniform.
The end portion of the emulsifier or the polymerization initiator used is likely to be present on the surface of the toner particles, and environmental characteristics are likely to be deteriorated.

In the present invention, the shape factor S of toner particles is
The suspension polymerization method under atmospheric pressure or under pressure is particularly preferable because the F-1 value can be controlled to 100 to 130, and a fine particle toner having a sharp particle size distribution and a particle size of 4 to 8 μm can be obtained relatively easily. . A seed polymerization method in which a monomer is further adsorbed on the polymer particles once obtained and then polymerized by using a polymerization initiator can also be suitably used in the present invention.
Furthermore, a salting-out association method or hetero-method in which primary emulsion-polymerized particles are formed in advance with little or no emulsifier, and then salting-out treatment or addition of polymerized particles having an opposite charge in an aqueous medium to bring them into contact with each other is carried out. A method for producing toner particles by an aggregation method can also be preferably used.

A more preferable toner used in the present invention is a toner particle shape factor SF measured by Luzex.
-1 is 100 to 130, and the low softening point compound is 5 to 3
It is preferable that the content of 0% by weight is further included, and the low softening point compound is encapsulated in the outer shell resin layer by a method of measuring a tomographic plane of a toner particle using a transmission electron microscope (TEM).

From the standpoint of fixability, it is necessary to incorporate a large amount of the low softening point compound in the toner, so that it is preferable that the low softening point compound is necessarily encapsulated in the outer shell resin. As a method of encapsulating the low-softening point compound in the toner particles, the polarity of the material in the aqueous medium is set to be smaller for the low-softening point compound than for the main monomer, and a small amount of a resin or a single resin having a large polarity is used. By adding the monomer, it is possible to obtain toner particles having a core-shell structure in which the low softening point compound is coated with the outer shell resin. Toner particle size distribution control and particle size control are carried out by changing the type and amount of the sparingly water-soluble inorganic salt or dispersant that acts as a protective colloid, and mechanical device conditions such as rotor speed, number of baths, stirring. It is possible by controlling the stirring conditions such as the shape of a blade, the shape of the container, or the solid content concentration in the aqueous solution.

The cross-sectional surface of the toner particles is heated at a temperature of 40 after the toner particles are sufficiently dispersed in a room temperature curable epoxy resin.
After curing for 2 days in an atmosphere of ℃, the cured product is dyed with ruthenium tetroxide and, if necessary, osmium tetroxide together, and cut into flaky samples using a microtome equipped with diamond teeth. The tomographic morphology of the toner particles can be observed using a transmission electron microscope (TEM). The ruthenium tetroxide dyeing method is preferably used in order to make a contrast between the materials by utilizing a slight difference in crystallinity between the low softening point compound and the resin constituting the outer shell. It is preferable that the low softening point compound is encapsulated by the outer shell resin as shown in FIG.

As the outer shell resin of the toner particles used in the present invention, a styrene- (meth) acrylic copolymer, a polyester resin, an epoxy resin or a styrene-butadiene copolymer can be used. In the method of directly obtaining toner particles by a polymerization method, a vinyl monomer is preferably used. Specifically, styrene, o (m-, p
-)-Methylstyrene, styrenic monomers such as m (p-)-ethylstyrene; methyl (meth) acrylate,
Ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, ( (Meth) acrylic acid ester monomers such as 2-ethylhexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; butadiene, isoprene, cyclohexene, (meth) acrylonitrile, An ene-based monomer such as acrylic acid amide is preferably used. These may be used alone or in the publication Polymer Handbook Second Edition III-P139-
A monomer is appropriately mixed and used so that the theoretical glass temperature (Tg) described in 192 (manufactured by John Wiley & Sons) is 40 to 75 ° C. When the theoretical glass transition temperature is lower than 40 ° C., the storage stability of the toner and the durability stability of the toner decrease, while when it exceeds 75 ° C., the fixing point increases. Particularly in the case of full-color toners, the color mixing properties of the respective color toners deteriorate, the color reproducibility is poor, and the transparency of the OHP image also deteriorates.

The molecular weight of the shell resin is measured by gel permeation chromatography (GPC). A specific method for measuring GPC is to extract the toner in advance using a Soxhlet extractor with a toluene solvent for 20 hours, and then distill off the toluene with a rotary evaporator to dissolve the low-softening point compound. Is an insoluble organic solvent (for example, chloroform), and after thorough washing, a solution soluble in tetrahydrofuran (THF) is filtered through a solvent-resistant membrane filter with a pore size of 0.3 μm. Made 150C
And the column configuration is Showa Denko A-801, 802,
The molecular weight distribution can be measured by connecting 803, 804, 805, 806 and 807 and using a calibration curve of a standard polystyrene resin. The number average molecular weight (Mn) of the obtained resin component is 5
000 to 1,000,000, and the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw / Mn)
Is preferably an outer shell resin showing 2 to 100 for the present invention.

In the present invention, it is particularly preferable to further add a polar resin in addition to the outer shell resin in order to encapsulate the low softening point compound in the outer shell resin. As the polar resin used in the present invention, a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a saturated polyester resin, or an epoxy resin is preferably used. It is particularly preferable that the polar resin does not contain an unsaturated group capable of reacting with the shell resin or the monomer in the molecule. When a polar resin having an unsaturated group is contained, a cross-linking reaction occurs with the monomer forming the outer shell resin layer, and the toner for full color has a very high molecular weight, which is unfavorable for color mixing.

As the colorant used in the present invention, carbon black, a magnetic substance, or a yellow / magenta / cyan colorant shown below, which is toned black, is used.

Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds,
A compound represented by an azo metal complex, a methine compound and an allylamide compound is used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 6
2, 74, 83, 93, 94, 95, 109, 110,
111, 128, 129, 147, 168 and the like are preferably used.

As the magenta colorant, a condensed azo compound, a diketopyrrolopyrrole compound, an anthraquinone, a quinacridone compound, a basic dye lake compound, a naphthol compound, a benzimidazolone compound, a thioindigo compound and a perylene compound are used. Specifically, C.I.
I. Pigment Red 2, 3, 5, 6, 7, 23, 4
8; 2, 48; 3, 48; 4, 57; 1, 81; 1, 1
44, 146, 166, 169, 177, 184, 18
5,202,206,220,221,254 are particularly preferred.

As the cyan colorant, a copper phthalocyanine compound and its derivative, an anthraquinone compound, a basic dye lake compound and the like can be used. Specifically, C.I. I.
Pigment Blue 1, 7, 15, 15: 1, 15: 2,
15: 3, 15: 4, 60, 62, 66 and the like can be preferably used.

These colorants can be used alone or in the form of a mixture, or in the state of a solid solution. The colorant is selected from the viewpoint of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in toner particles. The amount of the colorant added is
1 to 20 parts by weight is preferable with respect to 100 parts by weight of the resin.

When a magnetic material is used as the black colorant, unlike other colorants, it is 40% by weight with respect to 100 parts by weight of the resin.
It is preferable to use ˜150 parts by weight.

The charge control agent used in the present invention includes
Known ones can be used. In particular, a charge control agent that is colorless and has a high triboelectric charging speed of the toner and can stably maintain a constant charge amount is preferable. Further, when the direct polymerization method is used in the present invention, a charge control agent having no polymerization inhibitory property and having no solubilized product in an aqueous medium is particularly preferable. Specific compounds include, as negative charge control agents, metal compounds of salicylic acid, naphthoic acid, dicarboxylic acid or derivatives thereof; polymer type compounds having sulfonic acid or carboxylic acid in the side chain; boron compounds; urea compounds; Silicon compounds; curlyx arenes and the like can be mentioned. Examples of the positive charge control agent include organic quaternary ammonium salts, polymer type compounds having the quaternary ammonium salt in the side chain, guanidine compounds, and imidazole compounds. The amount of the charge control agent used is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the resin.
However, the addition of the charge control agent is not essential in the toner used in the present invention. When the two-component developing method is used, triboelectric charging with the carrier is used, and even when the non-magnetic one-component blade coating developing method is used, triboelectric charging with the blade member or the sleeve member is positively used. Therefore, it is not always necessary to include a charge control agent in the toner.

When the direct polymerization method is used for producing the toner particles, as the polymerization initiator, for example, 2,2'-azobis- (2,4-dimethylvaleronitrile) or 2,2'- is used.
Azo such as azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile -Type or diazo-type polymerization initiators: peroxide-type polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and lauroyl peroxide are used. The addition amount at the initiation of the polymerization varies depending on the intended degree of polymerization, but is generally 0.5 to 20% by weight with respect to the monomer. Although the type of the polymerization initiator varies slightly depending on the polymerization method, it may be used alone or in combination with reference to the 10-hour half-life temperature.

In order to control the degree of polymerization, known cross-linking agents, chain transfer agents, polymerization inhibitors and the like can be added to the monomer composition and used.

As an additive for imparting various toner characteristics, from the viewpoint of durability in the toner particles or when externally added to the toner particles, the volume average diameter of the toner particles is 1/5.
The following particle sizes are preferable. The particle size of the additive means the average particle size thereof obtained by observing the surface of the toner particles with an electron microscope. As the additives for imparting these characteristics, for example, the following ones are used.

1) Flowability-imparting agent: metal oxide powder (silicon oxide, aluminum oxide, titanium oxide, etc.), carbon black, carbon fluoride, etc. Those subjected to a hydrophobic treatment are more preferable.

2) Abrasive: Metal oxide powder (strontium titanate, cerium oxide, aluminum oxide, magnesium oxide, chromium oxide, etc.), nitride powder (silicon nitride, etc.), carbide powder (silicon carbide, etc.), metal salt Powder (calcium sulfate, barium sulfate, calcium carbonate)
Such.

3) Lubricants: Fluorine-based resin powders (vinylidene fluoride, polytetrafluoroethylene, etc.), fatty acid metal salt powders (zinc stearate, calcium stearate, etc.), etc.

4) Charge controllable particles: metal oxide powder (tin oxide, titanium oxide, zinc oxide, silicon oxide, aluminum oxide, etc.), carbon black, etc.

These additives are used in an amount of 0.1 to 10 parts by weight, preferably 100 parts by weight of the toner particles.
0.1-5 parts by weight are used. These additives may be used alone or in combination.

In the present invention, as a dispersant used when toner particles are produced by utilizing suspension polymerization, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, carbonic acid can be used as an inorganic compound. Examples thereof include magnesium, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica and alumina. Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, starch and the like. These can be used by dispersing them in the aqueous phase.
It is preferable to use 0.2 to 2.0 parts by weight of these dispersants with respect to 100 parts by weight of the polymerizable monomer.

Commercially available dispersants may be used as they are, but in order to obtain dispersed particles having a fine and uniform particle size, the inorganic compound may be formed in a dispersion medium under high-speed stirring. it can. For example, in the case of tricalcium phosphate, a dispersant suitable for the suspension polymerization method can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high speed stirring.

To make the dispersant finer, 0.001 to 0.
1% by weight of surfactant may be used in combination. Specifically, commercially available nonionic, anionic or cationic surfactants can be used. For example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate,
Examples thereof include calcium oleate.

When the direct polymerization method is used as the method for producing the toner particles used in the present invention, the toner particles can be specifically produced by the following production method.

A releasing agent comprising a low softening point compound, a colorant, a charge control agent, a polymerization initiator and other additives are added to the polymerizable monomer, and the mixture is homogenized by a dispersing means such as a homogenizer or an ultrasonic disperser. The dissolved or dispersed monomer composition is dispersed in an aqueous phase containing a dispersion stabilizer by an ordinary stirrer or a dispersing means such as a homomixer or a homogenizer. Preferably, the stirring speed and time are adjusted so that the droplets of the monomer composition have a desired toner particle size, and granulation is performed. After that, stirring may be performed to the extent that the particle state is maintained and the particles are prevented from settling due to the action of the dispersion stabilizer. Polymerization temperature is 40 ° C or higher, generally 5
It is preferable to carry out the polymerization by setting the temperature at 0 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction, and further, in order to remove unreacted polymerizable monomers, by-products, etc. that cause odor during toner fixing, in the latter half of the reaction or after the reaction is partially completed. The aqueous medium may be distilled off. After the reaction is completed, the produced toner particles are collected by washing and filtration and dried. In the suspension polymerization method, 300 parts of water is usually added to 100 parts by weight of the monomer composition.
It is preferred to use ˜3000 parts by weight as the dispersing medium.

The degree of aggregation in the present invention was measured by a powder tester (PT-D type manufactured by Hosokawa Micron Co., Ltd.) according to the following method. Measurement environment 23 ℃, 60%
RH.

(1) After leaving the toner in the measurement environment for 12 hours, 5.0 g is accurately weighed out.

(2) On the vibrating table, 60 mesh (opening 250 μm), 100 mesh (opening 150 μm) from the top.
m) and 200 mesh (opening 75 μm) sieves are overlaid and set.

(3) The precisely weighed 5.0 g of toner was gently placed on a sieve (on 60 mesh) and DC 1.7 to 1.7 was applied.
Vibrate at 5V for 15 seconds.

(4) Gently weigh accurately the amount of toner remaining on each sieve.

[0080]

[Outside 8]

Next, the particle size distribution measurement in the present invention will be described.

A Coulter counter T is used as a measuring device.
A-II type (manufactured by Coulter, Inc.)
Interface to output weight average distribution (made by Nikkaki)
And CX-1 personal computer (Canon)
Connected to the electrolyte using 1% sodium chloride using primary sodium chloride.
An aqueous Cl solution is prepared.

As a measuring method, the electrolytic aqueous solution 100 to 1 is used.
0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) as a dispersant is added to 50 ml, and 0.5 to 50 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and the Coulter Counter TA-II type is used to make an aperture of 2 to 40 using a 100 μm aperture.
The particle size distribution of μm particles is measured to obtain a weight average distribution and a number average distribution.

Further, external additives are appropriately added to the obtained toner particles to obtain a toner. In the case of a two-component developer, toner and carrier are added and mixed to obtain a developer.

The image forming method of the present invention can be used in both known magnetic / non-magnetic one-component type developer and two-component type developer, but in the case of one-component type developer, the developer is used. It is more preferable to use a two-component developer, because unevenness of the carrier is likely to appear on the image.

As the magnetic carrier used in the two-component developer, when the toner is a non-magnetic toner having a weight average particle diameter of 4 to 8 μm, the weight average particle diameter is 10 to 40 μm.
Saturation magnetization (σ
It is preferable that _s ) is 30 to 70 emu / g.

The saturation magnetization of the magnetic carrier is 70 emu / g
If it exceeds (for an applied magnetic field of 3000 oersteds), the magnetic brush composed of the toner and the magnetic carrier on the developer carrier (developing sleeve) facing the electrostatic latent image on the photoconductor at the time of development The sharpness of the ears became tight and the reproduction of gradation and halftone decreased, resulting in 30 emu.
If it is less than / g, it becomes difficult to satisfactorily retain the toner and the magnetic carrier on the developer carrying member, and problems such as adhesion of the magnetic carrier and toner scattering are likely to occur.

As the image bearing member used in the present invention, a fluorine-based and / or silicon-based compound is contained in the polycarbonate resin in an amount of 5.0 μm or less in the outermost layer within about 90 Å from the surface layer of the charge transport layer and / or the protective layer. Finely dispersed or solubilized particles can achieve high transfer efficiency of toner from the image carrier. It is particularly preferable when an intermediate transfer member is used.

A developing device that can be used in the image forming method of the present invention will be described with reference to FIG.

The present developing device is a non-magnetic material having a specific surface shape as a developer carrying member, which faces the electrostatic latent image carrying member 1 rotated in the direction of arrow a in the developing chamber 45 of the developing container 2. A developing sleeve (developer carrying member) 21 is provided, and a magnetic roller 22 as a magnetic field generating means is provided in the developing sleeve 21.
Is installed immovably, and the magnetic (magnet) roller 22 is S ₁ in order from the position of substantially the top in the rotation direction of arrow b,
It is magnetized to N ₁ , S ₂ , N ₂ and N ₃ .

In the developing chamber 45, the shape factor SF-1 is 1
The non-magnetic toner 40 and the magnetic carrier 4 which are 00 to 130
A two-component developer 41 in which 3 and 3 are mixed is stored.

When the developer 41 is fed into the stirring chamber 42 of the developing container 2 through one opening (not shown) of the partition wall 48 whose upper end is open at one end of the developing chamber 45, the developer 41 is discharged from the toner chamber 47 into the stirring chamber 42. To the other end of the stirring chamber 42 while being mixed by the first developer stirring / conveying means 50 in the stirring chamber 42.
The developer 41 conveyed to the other end of the stirring chamber 42 is separated by the partition wall 48.
Is returned to the inside of the developing chamber 45 through the other opening (not shown), and the second developer agitating / conveying means 5 in the developing chamber 45 is returned there.
1, and is supplied to the developing sleeve 21 while being agitated and conveyed by the third developer agitating / conveying means which conveys the developer in the direction opposite to the conveying direction by the conveying means 51 in the upper part of the developing chamber 45.

The developer 41 supplied to the developing sleeve 21.
Is magnetically restrained by the action of the magnetic force of the magnet roller 22, is carried on the developing sleeve 21, and is provided on the developing sleeve 21 substantially at the top thereof.
The developing unit 101 facing the electrostatic latent image bearing member 1 as the developing sleeve 21 rotates in the direction of the arrow b while being formed as a thin layer of the developer 41 on the developing sleeve 21 by the regulation of 1.
And is used for developing the electrostatic latent image on the electrostatic latent image carrier 1. The remaining developer 41 not consumed for the development is collected in the developing container 2 by the rotation of the developing sleeve 21.

In the developing container 2, the residual developer 41 remaining after the development, which is magnetically restrained on the developing sleeve 21 by the repulsive magnetic field between N ₂ and N ₃ having the same polarity, is peeled off. . In order to prevent the toner scattering when the developer 41 stands up along the lines of magnetic force by the magnetic pole N ₂ , an elastic seal member 31 is provided at the lower portion of the developer container 2 so that one end thereof contacts the developer 41. Fixed and installed.

The magnetic characteristics of the magnetic carrier are influenced by the magnet roller incorporated in the developing sleeve, and affect the developing characteristics and the transportability of the developer.

In the present invention, of the developing sleeve and the magnet roller incorporated therein, for example, the magnet roller is fixed and the developing sleeve is rotated by itself to form a two-component system composed of a magnetic carrier and an insulating non-magnetic color toner. The developer is circulated and conveyed on a developing sleeve to develop the electrostatic latent image held on the surface of the electrostatic latent image bearing member by the two-component developer, and the magnet roller has a repulsive pole. The magnetic flux density in the development area is 5
When the saturation magnetization of the magnetic carrier is 30 to 70 emu / g, the uniformity of the image, the gradation reproducibility, and the durability of a large number of sheets are excellent and suitable for color copying.

[0097]

EXAMPLES The present invention will be specifically described by the following examples.

Example 1 A developing sleeve (material) used in a developing unit of a full-color copying machine CLC500 (manufactured by Canon Inc.) having an OPC photosensitive drum, a developing unit for developing a magnetic brush, a transfer drum, a heating and pressure roller fixing unit and the like. : SUS, Hitachi Metals, diameter 2
Pneumatic blaster (made by Fuji Seisakusho)
Sandblasted using amorphous alumina particles having an average particle size of about 100 μ, using Ra = 2.1 μm and Sm = 2
Blast sleeve of 9.6 μm (Ra / Sm = 0.0
7) was produced.

The toner was prepared as follows. 710 parts by weight of ion-exchanged water and 0.1 mol / mol in a 2-liter four-necked flask equipped with a high-speed stirring device TK-Homomixer.
Was added l -Na ₃ PO ₄ aqueous solution 450 parts by weight,
The rotation speed was adjusted to 12,000 rpm and heated to 65 ° C. 68 parts by weight of 1.0 mol / liter-CaCl ₂ aqueous solution was gradually added to the mixture to form a fine water-insoluble dispersant C.
A dispersion medium containing a ₃ (PO ₄ ) ₂ was prepared. On the other hand, the monomer composition includes styrene monomer 165 parts by weight n-butylene acrylate monomer 35 unit parts C.I. I. Pigment Blue 15: 314 14 parts by weight Saturated polyester resin (terephthalic acid-propylene oxide modified bisphenol A acid value 15, peak molecular weight 6000) 10 parts by weight Dialkyl salicylic acid metal compound 2 parts by weight Ester wax [Compound (1)] (Endotherm in DSC Peak temperature 59.4 ° C, hardness 1.5) 60 parts by weight

After the above mixture was dispersed for 3 hours using an attritor, a monomer composition containing 10 parts by weight of 2,2'-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was added to an aqueous system. The mixture was put into a dispersion medium and granulated for 15 minutes while maintaining the rotation speed. After that, the stirrer was changed from a high-speed stirrer to a propeller stirrer, the internal temperature was raised to 80 ° C., and the polymerization was continued at 50 rpm for 10 hours. After the polymerization was completed, the slurry was cooled and diluted hydrochloric acid was added to remove the dispersant.
Cyan toner was obtained by further washing and drying. The weight average diameter of the cyan toner measured by a Coulter counter is 6.2 μm, the number variation coefficient is 27%, and S
F-1 was 104. A schematic diagram of a tomographic photograph of the obtained cyan toner is shown in FIG. This shows a structure in which an ester wax that is a low softening point compound is covered with an outer shell resin.
2% by weight of fine particles of hydrophobic titanium oxide are added to the obtained toner agent.
A cyan toner excellent in fluidity (aggregation degree 18%) was prepared by external addition.

Six parts by weight of this cyan toner and 94 parts by weight of a magnetic spherical ferrite carrier (weight average particle diameter 35 μm, σ _s 50 emu / g) coated with an acrylic resin are mixed to prepare a two-component developer, and the above-mentioned development is carried out. An endurance test of 5,000 sheets was conducted by magnetic brush development using a modified full-color copying machine CL500 having an OPC photosensitive drum using a cyan developing device incorporating a sleeve. The transfer efficiency was 95%, and a clear and excellent fixability image was stably obtained without fluctuation and unevenness of the image density. Neither fusion of the toner component on the surface of the developing sleeve was observed.

Next, as a yellow colorant, C.I. I. A yellow toner was prepared in the same manner as the cyan toner except that Pigment Yellow 17 was used. The obtained yellow toner has a shape factor SF-1 of 110, a weight average particle diameter of 6.7 μm, and a number variation coefficient of 30%.
Met. 2 wt% of hydrophobic titanium oxide fine powder was externally added to the yellow toner to prepare a yellow toner having a cohesion of 23%, and a two-component developer was prepared in the same manner as in Example 1.
It was introduced into a yellow color developing device.

Next, as a magenta colorant, C.I. I. A magenta toner was prepared in the same manner as the cyan toner except that Pigment Red 202 was used. The obtained magenta toner has a shape factor SF-1 of 104,
The weight average particle diameter is 7.0 μm, and the number variation coefficient is 29.
%Met. 2% by weight of hydrophobic titanium oxide fine powder was externally added to the magenta toner to prepare a magenta toner having an aggregation degree of 20%, and a two-component developer was prepared in the same manner as in Example 1.
It was introduced into a magenta color developing device.

Next, a black toner was prepared in the same manner as the cyan toner except that graft carbon black was used as the black colorant. The obtained black toner had a shape factor SF-1 of 106, a weight average particle diameter of 7.2 μm, and a number variation coefficient of 30%. A hydrophobic toner fine powder of 2% by weight was externally added to the black toner to prepare a black toner having an aggregation degree of 15%.
A two-component developer was prepared in the same manner as in 1. and introduced into the black color developing device.

Cyan developing device, yellow developing device,
A toner image for full color image is formed on the surface of plain paper by using a magenta color developing device and a black color developing device, and the toner image is fixed on the plain paper by a heating and pressure roller fixing device to form a full color image. Further, in the same manner, a full color image was formed on the back surface of the plain paper and a full color image was formed on both sides of the plain paper. The ester wax contained in the toner worked well and the offset phenomenon did not occur.

Example 2 Using the image forming procedure of Example 1, the toner and two-component developer used were prepared as follows.

Styrene-n-butyl acrylate copolymer 200 parts by weight C.I. I. Pigment Blue 15: 3 14 parts by weight Saturated polyester resin (terephthalic acid-propylene oxide modified bisphenol A acid value 15, peak molecular weight 6000) 10 parts by weight Dialkyl salicylic acid metal compound 2 parts by weight Ester wax [compound (1)] 15 parts by weight

The composition was thoroughly kneaded using an extruder, crushed and crushed to a target by using a jet flow, and further used an air flow classifier using the Counder effect. The weight average diameter was 8.2 μm and the number variation coefficient was To obtain 32% of pulverized cyan toner particles. Commercially available calcium phosphate fine powder is externally added to the cyan toner particles using a Henschel mixer, and the obtained mixed powder is dispersed in water using a homomixer. The water temperature is gradually raised and the temperature is increased to 80 ° C. for 3 hours. It was heat treated to make it spherical. After that, dilute hydrochloric acid was added to sufficiently dissolve and remove the calcium phosphate on the surface of the toner particles. Subsequently, it was washed and dried to obtain a cyan toner. The obtained cyan toner particles have a spherical shape under an electron microscope observation, the shape factor SF-1 has a value of 121, the weight average diameter is 7.8 μm, and the number variation coefficient is 29.
%Met.

A two-component developer (toner aggregation of 25%) was prepared from the obtained cyan toner by using the same external additive and carrier as in Example 1, and the same evaluation as in Example 1 was carried out. . At the initial stage of durability and at the time of 5,000 sheets, there was no fusion of the toner component or uneven distribution of the developer on the developing sleeve. Therefore, no image unevenness or background fog was observed, but the transfer efficiency from the OPC photosensitive drum to plain paper was 90%.
Met.

Example 3 A resin-coated developing sleeve was manufactured by uniformly applying a methyl ethyl ketone solvent of a phenol resin in which carbon black and graphite were dispersed on the developing sleeve used in Example 1, followed by drying and curing. The surface roughness of the obtained resin-coated developing sleeve was Ra = 1.7 μm,
Sm = 28.0 μm and Ra / Sm was 0.061.

Using the resin-coated developing sleeve, the two-component developer of Example 1 was used for image evaluation. At the initial stage of durability and at the time of 5,000 sheets, there was no fusion of the toner agent or uneven distribution of the toner on the resin-coated developing sleeve. Therefore, neither image unevenness nor background fog was observed.

Comparative Example 1 The surface roughness of the SUS developing sleeve was Ra = 0.1 μm.
m, Sm = 29.6 μm, Ra / Sm was 0.0034, and a two-component developer prepared in the same manner as in Example 1 was used to perform a durability test. From the 300th sheet of evaluation, the surface of the developing sleeve was not sufficiently coated with the developer, and as a result, the image density was as low as 1.0, and the image density difference between the left and right was 0.2 due to the uneven distribution of the developer.

Comparative Example 2 The surface roughness of the SUS developing sleeve was Ra = 0.2 μm.
m, Sm = 85.0 μm and Ra / Sm was 0.0024, and a durability test was conducted using a two-component developer prepared in the same manner as in Example 1. From the initial stage of the evaluation, the surface of the developer bearing member was not sufficiently coated with the developer. As a result, the image density was as low as 1.1, and the image density difference between the left and right was 0.32 due to the uneven distribution of the developer.

Comparative Example 3 The surface roughness of the SUS developing sleeve was Ra = 5.5 μ.
m, Sm = 12.0 μm and Ra / Sm was 0.458, and a durability test was conducted using a two-component developer prepared in the same manner as in Example 1. As a result of the evaluation, fusion of the toner component was recognized on the surface of the developing sleeve from the durability of 1500 sheets. As a result, the developer was not evenly coated on the developing sleeve, and an image having uneven image density was obtained. As a result, the image density was 1.6 at the initial stage, but the image density gradually decreased, and at the time of 1500 sheets, the image density decreased to 0.7. As for the image quality, particularly in the halftone, an image having a conspicuous graininess and poor gradation was obtained.

Comparative Example 4 The surface roughness of the SUS developing sleeve was Ra = 5.5 μ.
m, Sm = 9.0 μm and Ra / Sm of 0.61 were used, and a durability test was conducted using a two-component developer prepared in the same manner as in Example 1. From the 2300th sheet of evaluation, the surface of the developing sleeve was not sufficiently coated with the developer. As a result, the image density was low at 1.10, and the image density on the left and right was 0.15 due to the uneven distribution of the developer.

Comparative Example 5 A toner was prepared according to the following formulation using the crushing method.

Styrene-n-butyl acrylate copolymer 200 parts by weight C.I. I. Pigment Blue 15: 3 14 parts by weight Saturated polyester resin (terephthalic acid-propylene oxide modified bisphenol A acid value; 15 peak molecular weight; 6000) 10 parts by weight Dialkyl salicylic acid metal compound 2 parts by weight Ester wax [compound (1)] 34 parts by weight

After thoroughly kneading the above composition using an extruder, cooling the kneaded product, coarsely pulverizing the mixture, finely pulverizing the coarsely pulverized product by colliding with a collision plate using a jet stream, and further finely pulverizing the product. Using an air flow type classifier that utilizes the effect, the weight average diameter is 8.3 μm and the number variation coefficient is 37%,
A pulverized cyan toner having a SF-1 of 133 was obtained. The toner component was fused and fixed to the collision plate.

To the obtained cyan toner, 2% by weight of fine particles of hydrophobized titanium oxide was externally added to prepare a cyan toner having an aggregation degree of 68%, and then a two-component developer was prepared in the same manner as in Example 1. .

When an image was formed in the same manner as in Example 1 using the obtained two-component type developer, the transfer efficiency from the photosensitive drum to the plain paper was low at 78%.

Durability: When durability of 500 sheets is evaluated, durability is about 3
From 00 sheets, fusion of the toner component was recognized on the surface of the developing sleeve. As a result, the developer was not uniformly coated on the developing sleeve, and an image having uneven unevenness in image density was obtained. The aggregation degree of the toner of Example 1 is 18%
Although the toner of this comparative example had extremely high fluidity, the degree of aggregation of the toner of this comparative example was 68% and the fluidity was poor, so the initial image density was 1.02, and the image density gradually decreased. 5
At the time of 00 sheets, the image density has dropped to 0.75. As for the image quality, in comparison with Example 1, only an image having a poor gradation property, in which the graininess is noticeable particularly in the halftone, was obtained.

Comparative Example 6 A toner was prepared in the same manner as in Comparative Example 5 using the pulverization method and the following formulation.

Styrene-n-butyl acrylate copolymer 200 parts by weight C.I. I. Pigment Blue 15: 314 14 parts by weight Saturated polyester resin (terephthalic acid-propylene oxide modified bisphenol A acid value; 15 peak molecular weight;
6000) 10 parts by weight Dialkyl salicylic acid metal compound 2 parts by weight Ester wax [compound (1)] 6 parts by weight

The shape factor (SF-
1) was 152, and the weight average diameter of the cyan toner agent was 8.5 μm and the number variation coefficient was 36%. 2.0% by weight of hydrophobic titanium oxide fine powder was externally added to the cyan toner to prepare a cyan toner (aggregation degree: 35%), and then a two-component developer was prepared in the same manner as in Example 1 to prepare a cyan toner. It was introduced into a color developing device.

An image forming test was conducted in the same manner as in Example 1. As a result, from the endurance of about 4000 sheets, ultrafine particles were accumulated in the lowermost layer on the developing sleeve, and the cyan toner was not sufficiently charged, so that the image density was increased. Was observed. Further, when the fixing property was evaluated by a heating / pressurizing roller fixing device, the cyan toner of this comparative example was 40 ° C. lower in high temperature offset resistance than the cyan toner of Example 1.

Next, as a yellow colorant, C.I. I. A yellow toner was prepared in the same manner as the cyan toner except that Pigment Yellow 17 was used. The obtained yellow toner has a shape factor SF-1 of 155, a weight average particle diameter of 8.7 μm and a number variation coefficient of 39%.
Met. 2% by weight of hydrophobic titanium oxide fine powder was externally added to the yellow toner to prepare a yellow toner having a cohesion of 40%, and a two-component developer was prepared in the same manner as in Example 1 to color yellow It was introduced into the developing device.

Next, as a magenta colorant, C.I. I. A magenta toner was prepared in the same manner as the cyan toner except that Pigment Red 202 was used. The obtained magenta toner has a shape factor SF-1 of 153, a weight average particle diameter of 8.8 μm, and a number variation coefficient of 37%.
Met. 2% by weight of hydrophobic titanium oxide fine powder was externally added to the magenta toner to prepare a magenta toner having an aggregation degree of 36%. A two-component developer was prepared in the same manner as in Example 1, and the magenta color developing device was used. Introduced.

Next, a black toner was prepared in the same manner as the cyan toner except that graft carbon black was used as the black colorant. The obtained black toner had a shape factor SF-1 of 154, a weight average particle diameter of 9.0 μm and a number variation coefficient of 38%. A hydrophobic toner fine powder of 2% by weight was externally added to the black toner to prepare a black toner having an aggregation degree of 35%.
A two-component developer was prepared in the same manner as in 1. and introduced into the black color developing device.

Full-color images were formed on both sides of plain paper in the same manner as in Example 1, but high temperature offset was more likely to occur as compared with Example 1.

[0130]

According to the image forming method of the present invention, when a spherical toner containing a low softening point substance is applied by using a developer bearing member having a specific surface shape and continuous durability is performed. There is no image density unevenness or fog even in
The fusion of the developer does not occur on the developer carrier, and a stable image can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of the surface of a developer carrying member.

FIG. 2 is a schematic view showing a cross section of toner particles of Example 1.

FIG. 3 is a schematic explanatory diagram of an image forming apparatus to which the image forming method of the present invention can be applied.

[Explanation of symbols]

 1 image carrier 21 developer carrier

Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03G 9/08 311 9/087 13/08 G03G 9/08 365 381 384 13/08

Claims (13)

[Claims] 1. A developer carried on a developer carrying body is conveyed to a developing area, and in the developing area, an electrostatic latent image formed on the image carrying body is developed with the developer to carry a toner image. In the image forming method for forming on a body, the developer contains a toner having a low softening point compound in an amount of 5 to 30% by weight and having a shape factor SF-1 of 100 to 130. The surface of the carrier for supporting the developer has the following conditions: 0.2 μm ≦ center line average roughness (Ra) ≦ 5.0 μm 10 μm ≦ average interval of irregularities (Sm) ≦ 80 μm 0.05 ≦ Ra / Sm ≦ An image forming method characterized by satisfying 0.5. 2. The image forming method according to claim 1, wherein the back surface of the developer carrying member has a plurality of grooves in the major axis direction. 3. The surface of the developer carrying member has a plurality of grooves arranged at substantially equal intervals in the major axis direction.
The image forming method described in 1 .. 4. The image forming method according to claim 1, wherein the developer is a two-component developer having a toner and a magnetic carrier. 5. The toner has a weight average particle diameter of 4 to 8 μm and a number variation coefficient of 3 based on the toner number distribution.
The image forming method according to claim 1, which is 5% or less. 6. The image forming method according to claim 4, wherein the developer has a toner having a weight average particle diameter of 4 to 8 μm and a magnetic carrier having a weight average particle diameter of 10 to 40 μm. 7. The magnetic carrier has a saturation magnetization (σ of 30 to 70 emn / g in an applied magnetic field of 3000 Oersteds).
The image forming method according to claim 4, further comprising _s ). 8. The developer carrying member is a developing sleeve containing a magnetic field generating means, and the developing sleeve has a diameter of 12 to
The image forming method according to claim 1, which has a cylindrical shape of 30 mm. 9. The image forming method according to claim 8, wherein the developing sleeve has a cylindrical shape having a diameter of 15 to 25 mm. 10. The image forming method according to claim 1, wherein the toner has an aggregation degree of 30% or less. 11. The image forming method according to claim 10, wherein the toner has an aggregation degree of 3 to 25%. 12. The image forming method according to claim 1, wherein the low softening point compound is an ester wax. 13. The ester wax has a hardness of 0.5-.
The image forming method according to claim 12, having 5.0.