JPH06148926A - Method for forming image - Google Patents

Abstract

PURPOSE:To provide an image forming method which does not cause defective cleaning, the deterioration in image density and the defect of an image such as fogging caused by the particle shape of toner. CONSTITUTION:As for the image forming method including such a process that toner left on an image forming body 14 after transfer is eliminated by a cleaning device 33 provided with a blade 34, the toner constituting developer used for the image forming method satisfies the following condition. When shape coefficient S is defined to be S=(circumferential length)<2>/(area X4pi)X100, the number ratio A of a toner particle becoming S<116 to the whole particles is <=30%, the number ratio B of the toner particle becoming S>145, to the whole particles is <=30% and the total amount of the ratios A and B is <=40%.

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 including a step of removing transfer residual toner on an image forming body by a cleaning device equipped with a blade.

[0002]

2. Description of the Related Art Conventionally, as a technique capable of forming a high-quality and high-resolution image by using a device which is small in size, low in cost and excellent in operability, the pressing force of a developer amount regulator is utilized. A developing method has been introduced in which the developer adhered on the developer carrying carrier is thinned and the thin layer of the developer is developed in a non-contact manner with respect to the image forming body (JP-A-60-76).
766, etc.). In particular, this JP-A-60-767
In the multicolor image forming method disclosed in Japanese Patent Publication No. 66, since the developer is conveyed to the image forming body in a non-contact manner, the image on the image forming body is not disturbed by the developer and the image quality is high. It is an excellent development method that can be realized.

[0003]

(1) Poor cleaning However, in order to obtain an image having high resolution and excellent sharpness, it is an essential condition to use a toner having a small particle size. However, the smaller the toner particles, the greater the adhesion, so after the transfer step in the image forming process is completed,
A problem (cleaning failure) occurs in which the toner particles remaining on the image forming body cannot be completely removed by the cleaning blade, which causes image defects such as image distortion. It is known that the problem of cleaning failure is more likely to occur as the shape of the toner particles used is closer to a spherical shape and the unevenness on the surface of the toner particles is smaller. It is considered that this is because toner particles that are closer to a sphere and have less irregularities are more likely to rub through the blade. On the other hand, in order to solve the problem of such cleaning failure, the distortion coefficient of the toner particles [(maximum length) ² × π
/ (Area x 4) x 100] and the unevenness coefficient of the toner particles [(perimeter) ² / (area x 4π) x 100] average value are in specific ranges. (See Japanese Patent Laid-Open No. 61-279864). However, as a result of studies by the present inventors, when toner particles having a small unevenness coefficient are present at a constant ratio, cleaning failure occurs even if the average value of the unevenness coefficient and the distortion coefficient of the toner particles is large to some extent. It was confirmed that the above cannot be sufficiently prevented.

(2) Selection Phenomenon As described above, it is preferable to use a toner having a large unevenness from the viewpoint of improving the cleaning property. However, in the image forming process including the step of forming a thin layer on the developer transport carrier by using the pressing force of the developer amount regulating member, if toner particles having a large unevenness are used, the toner particles are provided at the time of forming the thin layer. Due to the pressing force from the developer amount regulating body, the toner particles are easily crushed to generate fine particles, and the fine particles adhere firmly to the developer carrying carrier and are difficult to develop (selection). Development)
By this selective development, the image density of the formed image is reduced. Further, there is a limit to reducing the unevenness of the toner particles in order to improve the cleaning property,
In addition, as a result of examination by the present inventors, when toner particles having a large unevenness coefficient are present at a constant ratio, even if the average value of the unevenness coefficient and the distortion coefficient of the toner particles is small to some extent, the selective development It was confirmed that the reduction of the image density cannot be sufficiently prevented.

(3) Image Defect In the technique described in Japanese Patent Laid-Open No. 61-279864, that is, the technique in which the respective average values of the distortion coefficient and unevenness coefficient of the toner particles used are considered,
If the particles containing these coefficients are too large or too small, not only the above problems of cleaning failure and the problems of selective development cannot be solved but also the charge distribution of the toner particles becomes too wide, resulting in formation. An image defect such as a fog is generated in the formed image.

On the other hand, in order to improve the fluidity and the charging property, a technique has been introduced which defines the unevenness coefficient of the toner and carrier, the distortion coefficient of the toner, etc.
185654). However, even in this technique, the maximum length for calculating the unevenness coefficient and the distortion coefficient,
The perimeter and the area are each obtained as an average value, and cannot be said to be a sufficient technique as a means for solving the above problems.

The present invention has been made under the above circumstances, and a first object of the present invention is an image forming method including a cleaning step by an apparatus equipped with a blade, which is defective in cleaning. An object of the present invention is to provide an image forming method which does not generate A second object of the present invention is to provide an image forming method including the above cleaning step and non-contact developing step, which does not cause a decrease in image density due to selective development. A third object of the present invention is to provide an image forming method that does not cause image defects such as fog.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention have individually examined the particle shape that tends to cause poor cleaning and the particle shape that tend to cause selective development, and
As a result of focusing on the distribution state of the particle shape rather than the average shape of the entire toner particle, cleaning failure and selective development can be performed by controlling the number ratio of particles having a specific shape coefficient (concave factor) to the entire toner particle. It was found that a high-quality image free of image defects such as fogging can be obtained without causing the above-mentioned problems, and the present invention has been completed based on such detection.

That is, the image forming method of the present invention constitutes a developer used in the image forming method in the image forming method including a step of removing the transfer residual toner on the image forming body by a cleaning device equipped with a blade. The toner is characterized by satisfying the following conditions. <Condition> The shape factor S is S = (perimeter) ² / (area × 4)
When defined as π) × 100, the number ratio A of the toner particles with S <116 to the entire toner particles is 30% or less. The number ratio B of the toner particles with S> 145 to the entire toner particles is 30% or less. The total of the number ratio A and the number ratio B is 40% or less.

Further, in the image forming method of the present invention, by utilizing the pressing force of the developer amount regulating member, the developer adhering to the developer carrying carrier is thinned and the thin layer of the developer is The electrostatic latent image on the image forming body is developed under the oscillating electric field obtained by conveying the developing medium in a non-contact state to the image forming body and applying an AC bias voltage to the developer conveying carrier. In the image forming method including a step and a step of removing the transfer residual toner on the image forming body by a cleaning device equipped with a blade, the toner constituting the developer used in the image forming method is a toner satisfying the above conditions. It is characterized by being.

In the image forming method of the present invention, primary particles having an average particle size of 0.1 to 3 μm, which are obtained by subjecting a polymerizable composition containing a polymerizable monomer to a polymerization reaction in an aqueous medium, are mutually separated. A developer produced by mixing a toner composed of secondary particles having an average particle diameter of 2 to 6 μm which are associated with each other and a resin-coated carrier is used.

[0012]

(1) When toner particles having a small unevenness coefficient are present at a constant ratio, it is not possible to sufficiently prevent defective cleaning even if the average value of the unevenness coefficient of the toner particles is large to some extent. . The present inventors have found that the toner particles adhering and remaining on the image forming body after the completion of the transfer step are observed for the particle shape, and that only the toner particles having a specific shape remain. This means that regardless of the average shape of the entire toner particles used for image formation, only the toner particles of a specific shape are involved in the occurrence of cleaning failure. Therefore, the inventors of the present invention think that the occurrence of cleaning failure can be suppressed by paying attention to the toner particles having the specific shape.
The shape factor S [S = (perimeter) ² / (area × 4)
π) × 100] was measured. As a result, most of the toner particles remaining on the image forming body have a shape factor S of 1.
The particles were less than 16. Further, as a result of examining the relationship between the content ratio (number ratio) of the toner particles of a specific shape to the entire toner particles and the cleaning property, the shape factor S
It has been found that by controlling the number ratio A of the toner particles having a ratio of less than 116 to 30 number% or less, good cleaning properties are exhibited.

(2) In the case where toner particles having a large unevenness coefficient are present at a constant ratio, even if the average value of the unevenness coefficient of the toner particles is small to some extent, the decrease in image density due to selective development is sufficiently prevented. Can not do it. Therefore, the present inventors have examined the relationship between the shape factor S of the toner particles to be used and the easiness of crushing due to the pressing force of the developer amount regulating member. As a result, when the shape factor S contains particles exceeding 145, Fine particles are likely to be generated by crushing toner particles,
It has been found that by controlling the number ratio B of toner particles having a shape factor S exceeding 145 to 30% or less, the occurrence of selective development and the like is prevented and an image having an appropriate image density is formed.

(3) In the present invention, the total (A + B) of the number ratio A of particles satisfying S <116 and the number ratio B of particles satisfying S> 145 is 40 number% or less.
Both the objectives of preventing the occurrence of defective cleaning and the prevention of selective development are satisfied in a well-balanced manner, and the charge distribution of toner particles becomes sharp, so that image defects such as fog do not occur in the formed image.

The present invention will be specifically described below. [Description of Toner] The present invention is characterized in that the shape (irregularity) distribution of the toner particles constituting the developer is defined in a specific range. Specifically, the shape factor S is calculated as “S = (perimeter) ² / (area × 4π) × 10
0 ", the toner particle number ratio A with S <116 is 30% or less, the toner particle number ratio B with S> 145 is 30% or less, and the number ratio (A +
The condition is that B) is 40% or less.

Number ratio A of toner particles with S <116
Is 30% or less, other toner particles having good cleaning properties (S ≧ 116) act like an abrasive, and as a result, good cleaning properties with a blade are exhibited. However, when the number ratio A exceeds 30%, this cleaning property is diminished and cleaning failure occurs. Further, if the toner particle number ratio B with S> 145 is 30% or less, the influence on the developing property is small, but this number ratio B
When it exceeds 30%, selective development due to pulverization of toner particles is likely to occur, resulting in a decrease in image density of an image formed. Further, when the number ratio (A + B) exceeds 40%, the triboelectrification areas become extremely different among the toner particles and the charge distribution becomes broad, so that fogging, toner scattering, etc. are likely to occur.

Here, the shape factor S represents the degree of unevenness of the toner particles, and S = 100 for a perfectly spherical toner particle having no unevenness. The shape factor S is measured by
First, an electron micrograph of toner particles is taken using a scanning electron microscope, and then the electron micrograph is input to an image analyzer "SPICCA" (manufactured by Nippon Avionics Co., Ltd.) using a video camera. The measurement is performed by measuring the perimeter and area of 500 toner particles. In the present invention, the peripheral length and area of each toner particle are measured to obtain the shape factor S of each particle.

The method for producing such a toner is not particularly limited as long as a toner satisfying the above-mentioned shape distribution can be obtained, but toner particles having a desired shape and particle diameter are efficiently used. From the viewpoint that it can be obtained, it is preferable to manufacture by associative polymerization. Specifically, a polymerizable composition containing a polymerizable monomer is subjected to a polymerization reaction in an aqueous medium to obtain primary particles having an average particle size of 0.1 to 3 μm,
Then, by associating these primary particles with each other,
A method of producing a toner composed of secondary particles having an average particle diameter of 2 to 6 μm can be mentioned. In the case of producing a toner by this associative polymerization, the shape factor S of the obtained toner particles can be controlled within the above-mentioned preferable range by adjusting the associating conditions (time) and the like.

The primary particles are obtained, for example, by an emulsion polymerization method. The secondary particles are particles in which the primary particles are bonded to each other by an ionic bond, a hydrogen bond, a metal coordination bond, a weak acid-weak base bond, a bond by Van der Waals force, or the like. Examples of the monomer for obtaining the primary particles include styrene-based monomers, acrylic-based monomers, and other polar group-containing monomers.

The styrene-based monomer is styrene, o
-Methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, p-ethyl styrene,
2,4-dimethylstyrene, pn-butylstyrene,
p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenyl styrene,
Examples thereof include p-chlorostyrene and 3,4-dichlorostyrene. Acrylic monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-acrylate.
Octyl, dodecyl acrylate, lauryl acrylate,
2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-chloromethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate , N-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like.

Other monomers having a polar group include
The following are listed. (1) Having acidic polar group Acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, maleic acid monooctyl ester, or metal thereof (Na, Zn, etc.) Carboxyl group (-C
Α, β-ethylenically unsaturated compound having OOH). Α, β- having a sulfo group (-SO ₃ H) such as sulfonated styrene or its Na salt, allylsulfosuccinic acid, octyl allylsulfosuccinate or its Na salt
Ethylenically unsaturated compounds.

(2) Having a basic polar group: dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, quaternary ammonium salts of these compounds, 3-dimethylaminophenyl acrylate, 2-hydroxy. -3-Methacryloxypropyltrimethylammonium salt or other amine group or quaternary ammonium salt group having 1 to 1 carbon atoms
(Meth) acrylic acid ester of aliphatic alcohol of 2. Acrylamide, N-butyl acrylamide, N,
N-dibutyl acrylamide, piperidyl acrylamide, methacrylamide, N-butyl methacrylamide,
(Meth) acrylic acid amides such as N, N-dimethylacrylamide, N-octadecylacrylamide or (meth) acrylic acid amides optionally substituted on N or di-alkyl. A vinyl compound substituted with a heterocyclic group having N as a ring member such as vinyl pyridine, vinyl pyrrolidone, vinyl N-methylpyridinium chloride and vinyl N-ethylpyridinium chloride. N, N-diallylmethylammonium chloride,
N, such as N, N-diallylethylammonium chloride,
N-diallylalkylamine.

In the monomer for obtaining the primary particles, the mixing ratio (weight ratio) of the styrene monomer and the acrylic monomer is preferably 90 to 20:10 to 80, and particularly 70
-30: 30-70 is preferable. The mixing ratio of the other monomer having a polar group is preferably 0.05 to 30 parts by weight, particularly 1 to 20 parts by weight, based on 100 parts by weight of the total of the styrene-based monomer and the acrylic-based monomer. Is preferred.

If desired, various additives may be contained in the composition for polymerization for obtaining the primary particles. Examples of such additives include colorants, release agents, charge control agents, and the like. As the colorant, carbon black, nigrosine dye, aniline blue, chalco oil blue, chrome yellow, ultramarine blue,
DuPont Oil Red, Quinoline Yellow, Methylene Blue Chloride, Phthalocyanine Blue, Malachite Green Oxalate, Lamp Black, Rose Bengal, mixtures thereof and the like. Examples of the releasing agent include low softening point polyolefin, high melting point paraffin wax, silicone varnish, aliphatic ester or partially saponified product thereof, aliphatic amide compound, and higher alcohol. Examples of the charge control agent include metal complex dyes, nigrosine dyes, ammonium salt compounds, and the like.

Further, external additives such as inorganic fine particles may be added to the toner obtained as described above. Examples of the inorganic fine particles include fine particles of silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, antimony trioxide, zirconium oxide, silicon carbide and the like. Is mentioned. Of these, silica is preferable. Further, from the viewpoint of durability, inorganic fine particles whose surface is subjected to a hydrophobic treatment are preferable.

[Explanation of Carrier] The carrier used in the present invention is not particularly limited, but a resin-coated carrier in which the surface of core material particles is coated with a resin is preferable. The resin for coating the carrier is not particularly limited, and typical examples thereof include silicone resins, fluorine resins, styrene-acrylic resins and the like.

Examples of the silicone-based resin include silicone varnish, silicone rubber, silicone resin and the like, but those having an organic group such as an alkyl group or an aromatic group as a constitutional unit are preferable, and a methyl group or a phenyl group is particularly preferable. Those having an organic group are preferable. Examples of the compound for obtaining the silicone-based resin having such an organic group include dimethylpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane, and modified products thereof. In particular, polysiloxane having a methyl group or a phenyl group has an excellent negative charging property. Further, in the above organic group, by appropriately selecting the content ratios of the methyl group and the phenyl group, it is possible to adjust the characteristics such as hardness, toughness, and triboelectricity of the coating layer of the carrier. The conditions required for the toner used in combination with are considerably relaxed, and the selection range of the toner becomes wide.

Commercially available products of silicone varnish are SR
2101, SH997, SH994, SR2202, S
E9140, SH643, SH2047, JCR610
0, JCR6101 (above, manufactured by Toray Silicone Co., Ltd.), KR271, KR272, KR274, KR21
6, KR280, KR282, KR261, KR26
0, KR255, KR266, KR251, KR15
5, KR152, KR214, KR220, X-4040
-171, KR201, SA-4, KR5202, KR
3093, EC1001 (above, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. Commercially available silicone rubber is SH
410, SH432, SH433, SH740, SH3
5U, SH75U, SH841U, SH1125U, S
H1603U, SH665U, SE955U, SH50
2U, SRX-440U (above, made by Toray Silicone Co., Ltd.), etc. are mentioned.

The fluorine-based resin is not particularly limited as long as it is a resin containing a fluorine atom, and for example, the following chemical formula 1
And a polymer obtained by polymerizing the monomer represented by the general formula (1) or (2), a vinylidene fluoride-tetrafluoroethylene copolymer, and the like.

[0030]

[Chemical 1]

(In the formula, R ¹ and R ² each represent a hydrogen atom or a methyl group, n and p each represent an integer of 1 to 8, and m and q each represent an integer of 1 to 19). Among the monomers represented by the general formula (1) or (2), the monomer represented by the general formula (3) or (4) of the following chemical formula 2 is preferable in terms of triboelectric charging property.

[0032]

[Chemical 2]

(In the formula, R ³ and R ⁴ each represent a hydrogen atom or a methyl group, r represents an integer of 1 to 2, and s represents 2
Represents an integer of 4; In addition, among the monomers represented by the general formula (1) or (2), methacrylic acid-
1,1-dihydroperfluoroethyl, methacrylic acid-
1,1,3-trihydroperfluoro-n-propyl and the like are preferable. When a vinylidene fluoride-tetrafluoroethylene copolymer is used, the copolymerization molar ratio of these is preferably 75:25 to 95: 5, particularly 7
The range of 5:25 to 87.5: 12.5 is preferable. Within such a range, the coating solution used for forming the coating layer can be easily prepared, and a resin-coated carrier having a large mechanical strength and excellent durability can be obtained. Specific examples of the fluorine-based resin include the following chemical formulas 3 and 4
However, the present invention is not limited to these. In the following specific examples, n represents an integer of 1 or more.

[0034]

[Chemical 3]

[0035]

[Chemical 4]

The styrene-acrylic resin is synthesized from a styrene monomer and an acrylic monomer. As the styrene-based monomer and the acrylic-based monomer, those similar to the styrene-based monomer and the acrylic-based monomer exemplified as the monomer for obtaining the primary particles in the toner are used. The weight ratio of the styrene-based monomer to the acrylic-based monomer is preferably 9: 1 to 1: 9. The styrene component makes the coating layer hard and the acrylic component makes the coating layer tough. Further, by appropriately changing the composition ratio of these, it is possible to considerably control the charge amount of the toner in the frictional charging between the resin-coated carrier and the toner. Further, the molecular weight of the styrene-acrylic resin is preferably a weight average molecular weight Mw of 30,000 to 200,000 from the viewpoint of enhancing the fixing strength of the coating layer and improving the durability.

The resin-coated carrier is prepared by dissolving a coating resin in an organic solvent to prepare a coating solution, and using this coating solution, for example, a dipping method, a spray drying method, a fluidized bed method, etc. The coating layer can be formed by applying it to the surface to form a coating layer, and then further heating or standing. It can also be formed by the dry coating method disclosed in JP-A-63-235959. As the core particles of the resin-coated carrier, conventionally known materials are used, and for example, ferromagnetic materials such as ferrite, magnetite and iron are preferably used. The weight average particle diameter of the resin-coated carrier is usually preferably 10 to 300 μm, and particularly preferably 20 to 100 μm.

[Description of Image Forming Process] FIG. 1 is a schematic explanatory view showing an example of an image forming apparatus that can be used in the present invention. In this image forming apparatus, the document table 10
Is moved, the original image emitted from the illumination light source 11 is emitted onto the image forming body 14 via the mirror 12 and the lens 13, thereby forming an electrostatic latent image. This electrostatic latent image is developed by the developing device H to form a toner image. Next, the toner image is discharged by the exposure lamp 15 to facilitate transfer, and then transferred to the recording paper P by the transfer pole 16. The recording paper P on which the toner image has been transferred is separated from the image forming body 14 by the separation pole 17, and the fixing device 3
It is fixed at 1. On the other hand, the transfer residual toner on the image forming body 14 is removed by the removing electrode 32 and the cleaning device 33. The cleaning device 33 includes a blade 34 for scraping off the transfer residual toner and a roller 36 for collecting the scraped toner.

FIG. 2 is a schematic explanatory view showing the structure of a non-contact developing device mounted on the above image forming apparatus. In the figure, reference numeral 20 denotes a developer carrying carrier, and this developer carrying carrier 20 has N and S alternating magnetic poles 8 which rotate in the arrow direction.
It is composed of a magnet roll 21 having a pole and a developing sleeve 22 which rotates in the opposite direction to the magnet roll 21 and conveys the developer layer to the developing area K. Reference numeral 23 is a developer amount regulating body composed of an elastic pressure contact plate that presses the developing sleeve 22 to regulate the layer thickness of the developer layer, 24 is an AC bias power source for forming an oscillating electric field, and 25 and 26 are arrows. Agitating device that rotates in a direction, 27 is a toner replenishing roller, 2
Reference numeral 8 is a toner hopper, and T is a replenishment toner. The magnetic pole strength (magnetic flux density) in the developing area of the magnet roll 21 is 5
This magnet roll 21 is set to have a Gauss of from 0 to 1500 gauss.
It may be rotated in the same direction as the developing sleeve 22 or may be fixed. Further, the number of magnetic poles may be appropriately selected within the range of 4 to 20 poles, but it is 6 from the viewpoint of evenly conveying the developer.
It is preferable that the number is extremely high. The developing sleeve 22 is
It is preferably made of a non-magnetic material such as copper, aluminum or magnesium. If necessary, the surface may be roughened by sandblasting or the like, and the surface may have high resistance. The pressing force of the developer amount regulator 23 is set to 0.1 to 5 g / cm and is desired to be 20 to 500 μm when performing non-contact development of a developer layer composed of a two-component developer.
It is suitable for forming a thin developer layer. In the developing area K, the gap between the image forming body 14 rotating in the direction of the arrow and the developing sleeve 22 is larger than the developer layer thickness and is usually 100 to 1000 μm, which enables non-contact development under an oscillating electric field. Is set as follows. With an AC bias power supply 24, usually at a frequency of 100 Hz to 10 kHz, preferably 1 to 5 kHz, usually 0.2 to 3.0 K
V (PP), preferably 1.0 to 2.0 KV (PP-
The bias of P) is applied. Further, in order to prevent the occurrence of fog, in the case of regular development, a DC bias of the same polarity as that of the electrostatic latent image is applied by being superposed by 50 to 500 V, and in the case of reversal development, the electrostatic latent image potential is applied. A close DC bias is applied. The stirring devices 25 and 26 are provided with a plurality of stirring blades inclined to their respective rotation axes, and each stirring blade is designed so as to rotate in the same region in an overlapping manner without colliding with each other. Therefore, the developer is moved and agitated in the direction of the rotation axis and in the direction perpendicular thereto, and the triboelectrification and uniform mixing of the developer are sufficiently achieved.

[0040]

EXAMPLES Examples of the present invention will be described below.
The invention is not limited to these examples. In addition, "part" represents a weight part below.

[Production of Toner] (1) Toner 1 100 parts of water and polyoxyethylene alkyl ether 1
Part, 1.5 parts of sodium alkylbenzene sulfonate, and 0.5 parts of potassium persulfate in an aqueous solution mixture, 60 parts of styrene, 40 parts of butyl acrylate, and 8 parts of acrylic acid as a monomer mixture (polymerizable). Composition) and polymerized at 70 ° C. for 8 hours with stirring to obtain a solid content of 50%.
An emulsion of primary particles was obtained. A mixture of 120 parts of the primary particle emulsion, 5 parts of nigrosine, 4 parts of pigment (carbon black), and 380 parts of water was held at about 30 ° C. for 2 hours while being dispersed and stirred with a slasher. Then, the temperature was raised to 70 ° C. with further stirring, and the temperature was maintained for 3 hours. During this time, when observed with a microscope, the primary particles associate
It was confirmed that secondary particles were obtained. Then cool down,
The obtained liquid dispersion was subjected to Buchner filtration, washed with water, and vacuum dried at 50 ° C. for 10 hours to obtain toner 1.

(2) Comparative Toner 1 In the production of Toner 1, the holding time at 70 ° C. is 1
Comparative Toner 1 was obtained in the same manner except that the time was changed. (3) Comparative Toner 2 In the production of Toner 1, the holding time at 70 ° C. was set to 7
Comparative Toner 2 was obtained in the same manner except that the time was changed. (4) Comparative Toner 3 The comparative toner 1 and the comparative toner 2 were appropriately mixed to obtain a comparative toner 3.

[Measurement of Shape Coefficient S] With respect to each of Toner 1 and Comparative Toners 1 to 3 obtained as described above, an electron microscope photograph (magnification 3500 times) of toner particles is taken by using a scanning electron microscope. did. Then, using a video camera (magnification: 4.5 times), the electron micrograph is taken and the image analysis device "SPICCA" (Japan Avionics Co., Ltd.)
Manufactured) and for each of the 500 toner particles,
The shape factor S was obtained by measuring the circumference and the area. Table 1 shows the average particle size and the number ratio of the shape factor S of these toners.

[0044]

[Table 1]

[Production of Carrier] Cu—Zn ferrite particles and a vinylidene fluoride-tetrafluoroethylene copolymer “VT-100” (copolymerization molar ratio: 80:20, using a conventional mixing and stirring device). (Manufactured by Daikin Industries, Ltd.) and a methyl methacrylate copolymer “Acrypet MF” (manufactured by Mitsubishi Rayon Co., Ltd.) were mixed and stirred, and then the obtained mixture was charged into an apparatus improved from an ordinary impact pulverization apparatus. The device was driven at a rotation speed of about 1/10 of that during normal crushing, and impact force was repeatedly applied to the mixture for 15 minutes to obtain a resin-coated carrier.

[Preparation of Developer] (1) Developer 1 To 50 parts of Toner 1, 1.2 parts of hydrophobic silica is added and mixed with a Henschel mixer to retain inorganic fine particles on the surface of the toner particles. After that, 950 parts of the above resin-coated carrier was added and mixed to prepare a developer 1 for the present invention. (2) Comparative Developers 1 to 3 Comparative Developers 1 to 3 were prepared in the same manner as the developer 1 except that Comparative Toners 1 to 3 were used instead of Toner 1.

[Embodiment 1] A non-contact reversal development type image forming apparatus "DC902" using the developer 1 as a developer.
8 "(manufactured by Konica Corp.) modified machine to form a black toner image on the image forming body, transfer the toner image onto transfer paper, and then fix it to form a fixed image. The image density stability, the cleaning property, and the presence or absence of fog were evaluated.

[Comparative Examples 1 to 3] An actual copying test was conducted in the same manner as in Example 1 except that the comparative developers 1 to 3 were used instead of the developer 1, and the image density stability, cleaning property, and The presence or absence of fog was evaluated. The image-forming test was stopped after 100 times of image formation in Comparative Example 2 and 300 times of image formation in Comparative Example 3.

Image Density Stability Image density stability was evaluated by measuring the image density at the initial stage of image formation and after 20,000 times formation. The image density was measured by forming a black solid image, measuring arbitrary 8 points of this image with a Macbeth densitometer "Macbeth RD918" to obtain the reflection density, and taking the average value as the image density. Cleanability The surface of the image forming body immediately after being cleaned by a device equipped with a blade was visually observed to observe the presence or absence of deposits on the surface of the image forming body. This observation is 100
The number of copies was measured at each time when image formation was repeated and many deposits were observed, and when practical problems such as image distortion occurred. The density of the non-image area was measured every 100 copies using the Kaburi Macbeth densitometer "Macbeth RD918".
Fog was defined as the time when the number became 1 or more, and the number of copies at that time was measured. The results of these evaluations are shown in Table 2.

[0050]

[Table 2]

In Comparative Example 1, the average particle diameter of the toner particles measured after forming 20,000 times was 3.0 μm, and it was confirmed that the toner particles were crushed. Further, fine particles generated at that time caused fog after 10,000 copies.

[0052]

According to the method of the present invention, with respect to the toner particles used for image formation, the number distribution of the shape factor S is regulated within a specific range. Therefore, cleaning failure and image density due to the toner particle shape are caused. Does not occur, and the charge distribution of the toner particles becomes sharp, and image defects such as fog do not occur.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of an image forming apparatus that can be used in the present invention.

FIG. 2 is a schematic explanatory diagram showing a configuration of a non-contact developing device mounted on the image forming apparatus.

[Explanation of symbols]

10 Document Plate 11 Illumination Light Source 12 Mirror 12 Lens 14 Image Forming Body 15 Exposure Lamp 16 Transfer Electrode 17 Separation Electrode 20 Developer Conveying Carrier 21 Magnet Roll 22 Developing Sleeve 23 Developer Amount Regulator 24 AC Bias Power Supply 25 Stirrer 26 Stirrer Device 27 Toner supply roller 28 Toner hopper 31 Fixing device 32 Eliminating electrode 33 Cleaning device 34 Blade 36 Roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mayumi Tanaka 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Stock Company

Claims (3)

[Claims] 1. An image forming method including a step of removing transfer residual toner on an image forming body by a cleaning device equipped with a blade, wherein a toner constituting a developer used in this image forming method satisfies the following conditions. And an image forming method. <Condition> The shape factor S is S = (perimeter) ² / (area × 4)
π) × 100, the number ratio A of toner particles satisfying S <116 to the entire toner particles is 30% or less, and the number ratio B of toner particles satisfying S> 145 to the entire toner particles is 30%. The total of the number ratio A and the number ratio B is 40% or less 2. A thin layer of the developer adhered on the developer transport carrier is utilized by utilizing the pressing force of the developer amount regulator, and the thin layer of the developer is not in contact with the image forming body. And a developing blade to develop the electrostatic latent image on the image forming body under an oscillating electric field obtained by applying an AC bias voltage to the developer carrying carrier, and cleaning with a blade. An image forming method including a step of removing transfer residual toner on an image forming body by an apparatus, wherein the toner constituting the developer used in this image forming method is the toner according to claim 1. Image forming method. 3. An average particle size of 0.1 to 3 μm obtained by polymerizing a polymerizable composition containing a polymerizable monomer in an aqueous medium.
average particle diameter of 2 to 6 μm in which primary particles of m are associated with each other.
3. The image forming method according to claim 1 or 2, wherein a developer produced by mixing the toner composed of the secondary particles described above with a resin-coated carrier is used.