JP2000267340A - Electrostatic toner - Google Patents

Abstract

(57) [Problem] To provide a good electrostatic latent image developing toner having high image quality and little transfer omission (worm biting) of the toner. A pulverizing method used in an image forming method in which a transfer unit is brought into contact with a part of an electrostatic charge holding member via a transfer material and a system for electrostatically transferring a toner image to a surface of the transfer material is provided. In the produced toner having at least a binder resin, a releasing agent and inorganic fine particles as a fluidity imparting agent, the volume average particle diameter M (μm) of the toner satisfies 4 to 7 μm and has a particle diameter of 5 μm or less. 60-toner particles
80% by number, the toner aggregation degree is 18% or less,
When the toner having the volume average particle size M is 2 <the toner volume average particle size <
A toner for electrostatic charge development, which satisfies a value represented by the following general formula when it is within the range of M + 2 (μm). (Equation 1)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus and an electrophotographic toner used in an electrophotographic method, an electrostatic printing method and the like.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for image quality of toner used in an electrophotographic developing method. An image forming apparatus using a digital image signal forms an image by forming a latent image of minute dots on a photoconductor and developing the latent image. At this time, if the particle diameter of the toner is large, the toner will protrude from the latent image dot, and a dot is not formed faithfully with respect to the latent image, so that a high quality image cannot be obtained. In order to solve this problem, a toner having a particle size of 5 μm or less is an essential component for forming a high-quality image, and a technique for using the toner is disclosed.

In Japanese Patent No. 2759516, a toner having a small particle size is used by defining the degree of aggregation and the range of the particle size distribution of toner particles.
0% or less, which was not sufficient in terms of image clarity. Also, in Japanese Patent No. 2768949, 5 μm
This is a method of obtaining a high quality image by making the volume variation coefficient of the toner particles sharp distribution with respect to the toner having 60% by number or more of the following particles. Had a problem.

When a dry toner is manufactured by a pulverizing method, the dry toner has an angular shape and an irregular shape. Since the toner is not easily separated from the body, all of the toner developed in the above-described transfer step is not transferred and remains on the photoreceptor, which is not preferable in terms of economy.

As a mechanism for transferring the toner from the electrostatic charge holding member to the transfer material, a non-contact transfer device using a corona discharge which generates a large amount of ozone in order to reduce the generation of ozone from environmental considerations. Accordingly, a contact type transfer device that electrostatically transfers a toner image to a transfer surface by bringing a transfer unit into contact with a part of the electrostatic charge holding member via a transfer material has been increasingly used. In this contact transfer method, the adhesion between the transfer material and the electrostatic charge holding member is easily obtained, and a high-quality transfer image is easily obtained. However, when the contact pressure is applied, pressure is also applied to the toner image on the electrostatic charge holding member, and toner aggregation occurs. As a result, the adhesive force with the electrostatic charge holding member is increased, and a phenomenon in which a portion having strong adhesion is not transferred onto the transfer material occurs. This phenomenon is generally noticeable in a line image, is called a “hollow-out phenomenon” in which a central portion is not transferred, and is regarded as a problem.

In particular, in the case of toner having a small particle size for high image quality, transfer failure is a serious problem. Generally, in order to improve this hollowing phenomenon, the adhesive force between the toner and the electrostatic image holding member may be reduced by simply adding a large amount of an additive such as silica commonly used as a toner additive. Can be improved by increasing the fluidity of the toner. However, in this method, there is a problem that the photoreceptor is damaged by a large amount of additives, and therefore, the amount that can be added is limited, and if a sufficient amount of silica or the like is used, the chargeability is adversely affected. There are also problems. That is, with respect to the chargeability, it is required to satisfy requirements such as charge amount, charge speed, charge amount distribution, toner mixing property and environmental stability, but when silica or the like is used, the charge speed, This has an adverse effect on the charge amount distribution, toner mixing properties, and environmental stability, and in some cases, phenomena such as image dust are also observed.

In addition, especially in recent years, images of a printer or the like used for image output of a computer or the like are required to have a higher density that is stable over time than a copying machine image, and the toner additive silica is sufficiently added. When such a toner is used, there is a problem that the silica itself has an extremely high insulating property, so that the silica is easily charged up, Q / M is abnormally increased, and the image density is reduced.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner for developing an electrostatic latent image having high image quality and less transfer loss (eating) of the toner.

[0009]

As a result of intensive studies, the inventor of the present invention has found that the above-mentioned problem is solved by the present invention which relates to (1) the method in which the transfer means is brought into contact with a part of the electrostatic charge holding member via a transfer material. In a toner having inorganic fine particles as at least a binder resin, a release agent and a fluidity imparting agent manufactured by a pulverization method used in an image forming method provided with a system for electrostatically transferring a toner image to a surface of a transfer material, Volume average particle size M of the toner
(Μm) satisfying 4 to 7 μm and containing 60 to 80% by number of toner particles having a particle diameter of 5 μm or less, having a toner aggregation degree of 18% or less, and a toner having a volume average particle diameter M of 2%. When the toner volume average particle diameter is within a range of <M + 2 (μm), the toner for electrostatic charge development satisfies a value represented by the following general formula.

[0010]

(Equation 2) (2) “The inorganic fine particles have a BET specific surface area of 170 m ² /
g), wherein the toner is made of a hydrophobized silica fine powder having a particle size of at least g, and (3) the inorganic fine particles whose surface is formed by hexamethylene disilazane. (4) The toner for electrostatic charge development according to the above (1) or (2), wherein the inorganic fine particles are composed of a hydrophobic silica fine powder and a hydrophobic oxidized powder. The toner for electrostatic charge development according to any one of the above (1) to (3), which is a mixture of fine titanium powders ", (5)" the content of the inorganic fine particles is 100% by weight of the toner. The amount is 0.3 to 3 parts by weight based on the amount of the toner for developing an electrostatic charge according to any one of the above items (1) to (4).

According to the study of the present inventors, it has been found that the contribution ratio of the toner having a small particle diameter of 5 μm or less is very high in order to obtain an image with good dot reproducibility. 60 toner particles
When it was less than a few percent, a clear image could not be obtained. 8
If it exceeds 0% by number, toner particles are likely to aggregate with each other, resulting in a toner mass larger than the original particle size, resulting in poor fluidity, rough image quality, reduced resolution, and worm-like transfer. There was a drawback that failure occurred. Here, the toner volume average particle diameter, the standard deviation of the volume distribution, the variation coefficient,
The number% of μm or less can be measured by various methods. In the present invention, a Coulter Counter TAII manufactured by Coulter Electronics Co., Ltd. of the United States was used.

On the other hand, when the degree of aggregation exceeds 18%, the fluidity of the toner is poor, resulting in an image with a large number of worm-like transfer defects, which is a problem. The aggregation degree of the toner is measured by various methods, and the aggregation degree in the present invention is measured by the following method. That is, this method is a method in which the toner is placed on the sieve and vibration is applied, and the degree of aggregation is determined from the weight of the toner remaining on the sieve. Specifically, the toner was measured using a powder tester PT-N type manufactured by Hosokawa Micron Corporation.
Using a combination of sieves of 75 μm (upper), 45 μm (middle), and 22 μm (lower), place 2 g of toner on the upper sieve, vibrate for 30 seconds at an amplitude of 1 mm, and leave toner remaining on each sieve. Was measured and calculated by the following equation, and the degree of agglomeration was determined using the following equation.

[0013]

## EQU3 ## {5 × (weight of toner remaining in upper row) + 3 × (weight of toner remaining in middle row) + (weight of toner remaining in lower row)} × 10

When the toner having a volume average particle size (M) falls within the range of 2 <the volume average particle size of the toner <M + 2 (μm), the following condition is satisfied: It has been found that the method of the present invention can be carried out without any problem, because the transfer of the toner to the toner by the insect is small.

[0015]

(Equation 4)

Here, the average circularity (SF1) is a shape index indicating the smoothness of the toner surface, and is closer to 1.00 as the toner surface is smoother and closer to a circle (sphere). When the shape index is 0.944 or more, since the toner surface is sufficiently smooth, the number of contacts with the image support decreases,
It was found that poor transfer of the toner from the electrostatic charge holding member to the transfer material was reduced, and that a good image could be obtained even with a toner having a particle size of 5 μm or less. This suggests that, in the present process, the toner circularity = 0.944 is a polarization point at which the transfer of a bug from the electrostatic charge holding member to the transfer material is defective. The shape index is measured by image analysis using an FPIA-1000 flow type particle image analyzer manufactured by Toa Medical Electronics Co., Ltd.

Further, the inorganic fine particles were measured by a BET method.
170m specific surface area by nitrogen adsorption ^Two/ G or more
High-quality images with excellent fluidity
Issued. 170m^Two/ G is smaller than / g
Is not sufficient, and poor transfer of insects is likely to occur.
Electricity was not enough and background stains on non-image areas occurred. This
It was more pronounced in the case of silica.

It has also been found that by containing the inorganic fine particles containing fine silica powder whose surface has been hydrophobized with hexamethylene disilazane, it is possible to provide a toner having excellent chargeability and less fogging. Also, since the inorganic fine particles are a mixture of hydrophobic silica fine powder and hydrophobic titanium fine powder, the Q / M of the charge amount observed when the silica alone is used with time is used to reduce the image density with titanium. By doing so, it has been found that the titanium has a lower resistance than the silica, and serves to release the charge charged up by the silica, so that the charge is more stabilized. Here, it turned out that sufficient fluidity cannot be obtained by using titanium alone. Further, it has been found that when the content of the inorganic fine particles is 0.3 to 3 parts by weight with respect to 100 parts by weight of the toner, a clear image can be obtained. When the addition amount of the inorganic fine particles was less than 0.3 parts by weight, the charging was not sufficient, and the background stain on the non-image area occurred. When the amount is more than 3 parts by weight, toner transfer dust is large and a clear image cannot be obtained.

Next, the materials used in the toner of the present invention will be described in detail. The polyester resin used as a binder in the present invention is obtained by condensation polymerization of an alcohol and a carboxylic acid, and the alcohol used is polyethylene glycol, diethylene glycol,
Diols such as triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butanediol, and 1,4-bis (hydroxymethyl) cyclohexane Bisphenols, such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylene bisphenol A, and divalent compounds obtained by substituting these with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms. And simple dihydric alcohols.

The carboxylic acids used to obtain the polyester resin include, for example, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, Succinic acid, adipic acid, sebacic acid, malonic acid, divalent organic acid monomers obtained by substituting these with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms, acid anhydrides thereof, lower alkyl esters; Examples thereof include a dimer of linoleic acid and other divalent organic acid monomers.

In order to obtain a polyester resin to be used as a binder resin, not only a polymer containing only the above-mentioned bifunctional monomer but also a polymer containing a component containing a trifunctional or more polyfunctional monomer is used. It is also suitable. Examples of the trifunctional or higher polyhydric alcohol monomer which is such a polyfunctional monomer include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sarbitan, pentaerythritol, dipentaerythritol, Tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,
2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, and others. be able to.

The trivalent or higher polycarboxylic acid monomer includes, for example, 1,2,4-benzenetricarboxylic acid,
1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid , 1,2,5
-Hexanetricarboxylic acid, 1,3-dicarboxyl-
Examples thereof include 2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, empole trimer acid, acid anhydrides thereof, and others.

As the binder resin used together with the polyester used in the present invention, all known resins can be used. For example, polystyrene, poly-p-chlorostyrene, homopolymers of styrene such as polyvinyltoluene and substituted products thereof; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, Styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer Polymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene -Vinyl ethyl ether copolymer, Styrene - vinyl methyl ketone copolymer, styrene - butadiene copolymer, styrene -
Styrene-based copolymers such as an isoprene copolymer, a styrene-acrylonitrile-indene copolymer, a styrene-maleic acid copolymer, and a styrene-maleic acid ester copolymer are exemplified.

Further, the following resins can be mixed and used. Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic Or an alicyclic hydrocarbon resin, an aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like.

The following binder resins are particularly suitable for pressure fixing, and may be used in combination. Polyolefin (low molecular weight polyethylene, low molecular weight polypropylene, polyethylene oxide, polytetrafluoroethylene, etc.), epoxy resin, polyester resin, styrene-butadiene copolymer (monomer ratio 5-30: 95-7)
0), olefin copolymer (ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, Ethylene-vinyl acetate copolymer, ionomer resin), polyvinyl pyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resin, phenol-modified terpene resin, and the like.

As the charge control agent contained in the toner of the present invention, all conventionally known charge control agents can be used. Examples of positive charge control agents include nigrosine, basic dyes, lake dyes of basic dyes, quaternary ammonium salt compounds, and the like.As negative charge control agents, metal salts of monoazo dyes,
Metal complexes of salicylic acid, naphthoic acid, dicarboxylic acid, and the like. The amount of the polar control agent used is determined by the type of the binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not specifically limited. Is used in an amount of 0.01 to 8 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the binder resin. If the amount is less than 0.01 part by weight, the effect of the change in the charge amount Q / M at the time of environmental change is small, and if it exceeds 7 parts by weight, the low-temperature fixability is inferior.

As the release agent used for the toner in the present invention, all known release agents can be used, and in particular, free fatty acid type carnauba wax, montan wax and rice oxide wax can be used alone or in combination. . Carnauba wax is preferably a microcrystalline wax, and preferably has an acid value of 5 or less and a particle diameter of 1 μm or less when dispersed in a toner binder. The montan wax generally refers to a montan-based wax refined from a mineral, and is preferably a microcrystal and has an acid value of 5 to 14 like carnauba wax. The oxidized rice wax is obtained by oxidizing rice bran wax with air, and preferably has an acid value of 10 to 30.
When the acid value of each wax is less than the respective range, the low-temperature fixing temperature increases, and the low-temperature fixing becomes insufficient. Conversely, when the acid value exceeds each range, the cold offset temperature increases, and the low-temperature fixing becomes insufficient. The amount of the wax added is 1 to 1 with respect to 100 parts by weight of the binder resin.
It is used in an amount of 5 parts by weight, preferably 3 to 10 parts by weight. If the amount is less than 1 part by weight, the releasing effect is thin and a desired effect is hardly obtained. Further, when the amount exceeds 15 parts by weight, problems such as remarkable spent on the carrier occur.

Further, the toner of the present invention contains a magnetic material and can be used as a magnetic toner. As the magnetic material contained in the magnetic toner of the present invention, magnetite, hematite, ferrite and other acid values iron, iron, cobalt, metals such as nickel or aluminum of these metals,
Examples include alloys of metals such as cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof. These ferromagnetic materials preferably have an average particle size of about 0.1 to 2 μm.
About 20 to 200 parts by weight, particularly preferably about 40 to 15 parts by weight, per 100 parts by weight of the resin component.
0 parts by weight.

As the colorant, any known colorants can be used. As the black colorant, for example, carbon black, alinine black, furnace black, lamp black and the like can be used. As the cyan coloring agent, for example, phthalocyanine blue, methylene blue, Victoria blue, methyl violet, aniline blue, ultramarine blue and the like can be used. As the magenta colorant, for example, Rhodamine 6G Lake, dimethylquinacridone, Watching Red, Rose Bengal, Rhodamine B, Alizarin Lake and the like can be used. As the yellow colorant, for example, chrome yellow, benzidine yellow, hansa yellow, naphthol yellow, molybdenum yellow, quinoline yellow, tartrazine and the like can be used.

Further, the toner of the present invention may optionally contain additives. Examples of additives include lubricants such as Teflon and zinc stearate, abrasives such as cerium oxide and silicon carbide, fluidity imparting agents such as aluminum oxide, anti-caking agents, and conductivity imparting such as carbon black and tin oxide. And fixing aids such as low molecular weight polyolefins.

As the hydrophobic silica particles used in the present invention, all known silica particles can be used. Examples of hydrophobizing agents such as silane coupling agents, silicone varnishes, silicone oils, organosilicon compounds, and these substances having functional groups include hexamethyldisilazane, hexamethylenedisilazane, trimethylsilane, trimethylchlor. Silane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, benzyldimethylchlorosilane, chloromethyldimethylchlorosilane,
Dichlorodimethylsilane, triorganosilylmercaptan, trimethylsilylmercaptan, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, aminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane , Dibutylaminopropylmethyldimethoxysilane, trimethoxysilyl-γ-propylphenylamine and the like. Silicone oils include methyl silicone oil, dimethyl silicone oil, phenyl methyl silicone oil, chlorophenyl methyl silicone oil, alkyl-modified silicone oil, fatty acid-modified silicone oil, amino-modified silicone oil,
And polyoxyalkyl-modified silicone oils. These are used alone or as a mixture of two or more. In the above processes, a single process or various processes may be used in combination.

As the hydrophobic titanium particles used in the present invention, all known ones can be used. Examples of the surface treatment agent include various silicone oils such as methyl hydrogen polysiloxane, dimethyl polysiloxane, and methylphenyl polysiloxane, methyl trimethoxy silane, ethyl trimethoxy silane, hexyl trimethoxy silane,
Octyltrimethoxysilane, decyltrimethoxysilane, octadecyltrimethoxysilane, dimethyldimethoxysilane, octyltriethoxysilane, n-octadecyldimethyl (3-trimethoxysilyl) propyl)
Various alkylsilanes such as ammonium chloride Various fluoroalkylsilanes such as trifluoromethylethyltrimethoxysilane and heptadecafluorodecyltrimethoxysilane, particularly vinyltrimethoxysilane, γ-
Any of silane-based, titanium-based, aluminum-based, and alumina-zirconia-based metal-based coupling agents represented by silane coupling agents such as aminopropyltrimethoxysilane can be used. A mixture of more than one species can be used.

Further, as the carrier that can be used in the present invention, all known carriers can be used, for example, iron powder,
Magnetic powder such as ferrite powder and nickel powder,
Glass beads and the like, and those obtained by treating the surface of the beads with a resin or the like can be used.

In the present invention, the resin powder that can be coated on the carrier includes a styrene-acryl copolymer,
Silicone resin, maleic resin, fluorine resin, polyester resin, epoxy resin and the like are available. In the case of a styrene-acrylic copolymer, those having a styrene content of 30 to 90% by weight are preferred. In this case, if the styrene content is less than 30%, the developing characteristics are low, and if the styrene content exceeds 90% by weight, the coating film becomes hard and easily peels off, shortening the life of the carrier. In addition, the resin coating of the carrier in the present invention may contain an adhesion-imparting agent, a curing agent, a lubricant, a conductive agent, a charge control agent, and the like, in addition to the above resin.

The present invention also maintains the advantages of the conventional silicone resin-coated carrier by coating the surface of the core particles with a silicone resin containing a conductive fine powder and a silane coupling agent. By imparting conductivity to the carrier, it is possible to effectively suppress the phenomenon of charge accumulation on the carrier, peeling of the coating layer, and detachment of the conductive fine powder.

In the present invention, the carrier core particles coated with the silicone resin may be those conventionally known, for example, ferromagnetic metals such as iron, cobalt and nickel; alloys and compounds such as magnetite, hematite and ferrite; Glass beads and the like can be mentioned. The average particle size of these core particles is usually 10 to 1000 μm, preferably 30 to 5 μm.
00 μm. The amount of the silicone resin used is usually 1 to 10% by weight based on the carrier core particles.

The silicone resin used in the present invention may be any conventionally known silicone resin. For example, KR261, KR271, KR272, and KR manufactured by Shin-Etsu Silicone Co., which are commercially available.
275, KR280, KR282, KR285, KR2
51, KR155, KR220, KR201, KR20
4, KR205, KR206, SA-4, ES100
1, ES1001N, ES1002T, KR3093, SR2100, SR2101, S
R2107, SR2110, SR2108, SR210
9, SR2115, SR2400, SR2410, SR
2411, SH805, SH806A, SH840 and the like are used. As a method for forming the silicone resin layer, the silicone resin may be applied to the surface of the carrier core particles by a spraying method, an immersion method, or the like, as in the related art. The coating layer composition is prepared by adding a conductive fine powder and a silane coupling agent to a silicone resin solution and dispersing the mixture with an appropriate mixer.

The amount of the conductive fine powder dispersed in the coating layer is 0.1.
The particles having a particle size of about 01 to 5.0 μm are preferred, and 0.01 to 30 parts by weight are preferably added to 100 parts by weight of the silicone resin, more preferably 0.1 to 20 parts by weight. As the conductive fine powder, conventionally known carbon black may be used, and examples thereof include contact black, furnace black, and thermal black.

As the silane coupling agent,

[0040]

Embedded image A compound represented by the formula X—Si— (OR) ₃ (where X is a functional group that reacts with an organic substance and R is a hydrolyzable group) can be used. As the carrier for positive charging, an aminosilane coupling agent having an amino group may be mentioned, and as the carrier for negative charging, an epoxysilane coupling agent having an epoxy group may be mentioned. The content of the silane coupling agent is 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the silicone resin.

[0041]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In addition,
All parts are parts by weight. First, a production example of a carrier having a silicone resin in a coating layer will be described. These can be performed by known means.

[Production Example of Carrier Particles] Silicone resin solution (KR251, manufactured by Shin-Etsu Silicone Co., Ltd.) 100 parts Aminosilane coupling agent 1 part Carbon black (# 44, manufactured by Mitsubishi Chemical Corporation) 4 parts Toluene 100 parts The mixture was dispersed by a mixer to prepare a coating layer forming liquid. This coating layer forming liquid is converted into magnetite core particles (III).
A coating layer was formed on a surface of 1,000 parts by weight using a fluidized bed type coating apparatus to obtain a carrier A.

Next, a production example of the toner will be described. These can be performed by known means. [Toner Production Example 1] Polyester resin (weight average molecular weight 300,000) 70 parts Styrene-methyl methacrylate copolymer 30 parts Carbon black (# 44, manufactured by Mitsubishi Carbon Corporation) 9 parts Oxidized rice wax (acid value 10) 6 parts included Metal azo dye 4 parts After sufficiently mixing and mixing the mixture having the above composition in a Henschel mixer, about 3 to about 130 °
After heating and melting for 0 minutes and cooling to room temperature, the obtained kneaded material was pulverized by a mechanical pulverizer and classified by an elbow jet classifier to obtain a toner having a particle size distribution shown in Table 1.

[Additive Mixing] A predetermined amount of an additive was added to 100 parts of the toner, and the mixture was stirred and mixed with a Henschel mixer. Then, large-sized particles were removed through a mesh to obtain a final toner. [Developer Production] To 2.5 parts of the toner, a carrier A
97.5 parts were mixed with a ball mill to obtain a developer.

The evaluation of each toner was performed as follows. A copying machine MF-2 manufactured by Ricoh Co., Ltd. having a system in which a transfer unit is brought into contact with a part of the electrostatic charge holding member via a transfer material to electrostatically transfer a toner image to the surface of the transfer material.
Using 00, the image quality of each toner was evaluated. Table 1 shows the contents in each developer. Table 2 shows the image evaluation results.

[Evaluation Method and Evaluation Criteria] <Evaluation of Insect Eating> Character chart ("machine")
, 1 line, 19 characters, 10 points, Ming Dynasty), the number of missing transfer (insect-eating) characters on each line is counted, and the number of missing transfer (insect-eating) characters is calculated as follows: The evaluation was made in five steps according to the criteria. ◎: Very good ○: Good □: Normal △: Bad ×: Very bad

<Image Quality> The image quality (fine line reproducibility) was evaluated in five steps based on the following criteria based on the fine line reproducibility on the copied image at the initial stage and after 100,000 copies. ◎: Very good ○: Good □: Normal △: Bad ×: Very bad

<Image Density> A black solid original was output in A4 size, and the image density was evaluated in five steps according to the following criteria. ◎: Very good ○: Good □: Normal △: Bad ×: Very bad

<Surface Stain> The background stain was evaluated for the initial and 10
The density of the toner adhering to the non-image area after 10,000 sheets was evaluated in five steps according to the following criteria. ◎: Very good ○: Good □: Normal △: Bad ×: Very bad

<Transfer Chile> The transfer chile evaluation was 10
The degree of the toner dust on the copied image after 10,000 copies was evaluated in five steps according to the following criteria. ◎: Very good ○: Good □: Normal △: Bad ×: Very bad

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

As is apparent from the above detailed and specific description, the use of the toner of the present invention having a specific particle size, agglomeration degree and shape in a developer provides high image quality and toner transfer. It is possible to provide a good toner for developing an electrostatic latent image with less omission (worm biting).

Claims (5)

[Claims] A pulverization method used in an image forming method provided with a system for transferring a toner image to a surface of a transfer material by bringing a transfer unit into contact with a part of the electrostatic charge holding member via a transfer material. The toner having inorganic fine particles as at least a binder resin, a release agent and a fluidity imparting agent produced by the method described above, the volume average particle diameter M (μm) of the toner satisfies 4 to 7 μm and the particle diameter of 5 μm or less. The toner particles
80% by number, the toner aggregation degree is 18% or less,
When the toner having the volume average particle size M is 2 <the toner volume average particle size <
A toner for electrostatic charge development, which satisfies a value represented by the following general formula when it is within the range of M + 2 (μm). (Equation 1) 2. The inorganic fine particles having a BET specific surface area of 170
^2. The electrostatic charge developing toner according to claim 1, comprising a silica fine powder having a hydrophobicity of not less than m ² / g. 3. The electrostatic charge developing toner according to claim 1, wherein the inorganic fine particles comprise a fine powder whose surface is subjected to a hydrophobic treatment with hexamethylene disilazane. 4. The electrostatic charge developing toner according to claim 1, wherein the inorganic fine particles are a mixture of hydrophobic silica fine powder and hydrophobic titanium oxide fine powder. 5. The electrostatic charge developing device according to claim 1, wherein the content of the inorganic fine particles is 0.3 to 3 parts by weight based on 100 parts by weight of the toner. toner.