JPH06332252A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To provide the toner having excellent cleanability and electrostatic charge stability, high production efficiency and small grain sizes by pulverizing large particles which are obtd. by a wet process granulation method and internally have hollows. CONSTITUTION:The particles of the relatively large grain sizes having the hollows are granulated from a toner compsn. component contg. at least a resin and coloring agents and are then pulverized Namely, a liquid suspension contg. the large hollow particles obtd. by the wet process granulation method is previously mixed in a premix tank 1 and then, the prescribed amt. thereof is sent into a vessel 3 by a feed pump 2. Ottawa sand is incorporated as media 7 into this vessel 3. The large hollow particles in the liquid suspension pass between the inside wall surface of the vessel and disks 4 and are pulverized while coming into collision against the media 7 according to the rotation of the disks 4. The liquid suspension contg. the small grain sizes pulverized to the desired grain sizes in such a manner is separated from the media 7 and the prescribed amt. thereof is sent into a stock tank 6 by a pump 5. The suspension is subjected to a drying stage, by which the toner particles are obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used for developing an electrostatic image formed by electrophotography, electrostatic printing, electrostatic recording, etc. It is about.

[0002]

2. Description of the Related Art In recent years, a reduction in the particle size of toner has been studied for the purpose of high definition of images in electrophotography. A jet mill is used as a crusher for a normal kneading and crushing type toner. The jet mill collides a lump of toner with a collision plate to pulverize it, but in order to obtain a toner having a small particle size, it is necessary to increase the speed at which the lump of toner collides with the collision plate. However, as a result, a large amount of fine powder finely pulverized to a desired particle size or less is generated. Further, when the powder is crushed with a weak force to suppress this, the powder is not sufficiently crushed to a desired particle size and coarse powder is generated. If the amount of fine powder is large, problems such as toner scattering and filming of toner on the surface of the photoconductor occur, and if the amount of coarse powder is large, the toner charge amount is reduced and the image quality is deteriorated. Therefore, the toner obtained by the conventional pulverization method has a wide particle size distribution of the toner particles, and there is a limit to the reduction of the particle size of the toner in terms of productivity or productivity such as yield.

On the other hand, particles having a small particle size and a relatively narrow particle size distribution can be obtained, and as a method more advantageous in terms of productivity than the pulverization method, a suspension polymerization method, a suspension granulation method, or the like is used. Wet granulation methods have already been proposed. This method is a method of adding a polymerizable monomer, a colorant, and other additives, synthesizing the toner in a suspended state, and granulating. In order to manufacture a toner having a uniform small particle diameter, it is overwhelmingly advantageous to manufacture the toner by a wet method rather than a pulverization method which is a conventional toner manufacturing method.

[0004]

However, the toner obtained by the wet method is generally spherical in shape and has a very smooth surface. Therefore, there is a problem in that when the toner attached to the photoconductor is blade-cleaned, the toner slips between the photoconductor and the blade and cleaning cannot be sufficiently performed.

Further, the toner obtained by the wet method is liable to be mixed with a solvent, a dispersion liquid and the like inside thereof, and after these are evaporated, this portion becomes a bubble. In the configuration in which the polymerization initiator is added, gas is generated from the polymerization initiator to form bubbles inside the toner particles. With such toner particles, the toner particles are easily broken when the toner is mixed and stirred. As a result, fine powder is generated, which causes adverse effects such as toner filming on the surface of the photoconductor and toner spent on the carrier.

Further, the toner obtained by the wet method has a large amount of polymerization initiators, additives and the like attached to the surface thereof, which adversely affects the chargeability of the toner.

Therefore, an object of the present invention is to provide a toner for developing an electrostatic image having a small particle size, which solves the above-mentioned problems and is excellent in cleaning property and capable of obtaining a high quality image.

Another object of the present invention is to provide a small particle size electrostatic charge developing toner excellent in charging stability.

[0009]

The present invention is characterized in that a relatively large particle having a hollow is granulated from a toner composition containing at least a resin and a colorant, and then pulverized. is there.

Particles having hollows are easily pulverized, and in the present invention, a toner having a small particle diameter can be efficiently obtained by obtaining particles having hollows in a stage before pulverization. Further, the obtained toner has an irregular shape, and the cleaning failure peculiar to the small particle diameter toner obtained by the conventional wet method is also improved. It also improves the influence of various additives attached to the toner surface on the charging property.

The toner for developing an electrostatic image of the present invention is obtained by first obtaining a relatively large particle having a hollow from a toner composition containing at least a resin and a colorant by a wet method (hereinafter referred to as a large hollow particle). It is obtained by crushing this.

In the present invention, the wet method is a suspension polymerization method,
It includes all methods capable of forming hollows in particles, such as emulsion polymerization method, non-aqueous dispersion polymerization method, emulsion dispersion granulation method and spray drying method. In particular, from the viewpoint of the variety of resins used, the uniformity of resin dispersion, the ease of adjusting the molecular weight, the dispersibility of pigments or charge control agents, etc., the emulsion dispersion granulation method, the suspension polymerization method, and the spraying method. The drying method is preferred.

When the hollow large particles are prepared by a suspension polymerization method, an emulsion polymerization method or a non-aqueous dispersion polymerization method, the above method is carried out in the state where desired additives such as a colorant and a charge control agent are added during the polymerization. It may be carried out, and in the case of the emulsion dispersion granulation method or the spray drying method, the method may be carried out by adding the additives necessary for the toner to the resin solution.

The particles obtained by the wet method generally tend to have bubbles inside, and in particular, the toner particles obtained by the emulsion dispersion granulation method have a hollow region of about 10 to 30%, and the suspension polymerization method. The toner particles obtained by the emulsion polymerization method and the non-aqueous dispersion polymerization method also have a hollow region of about 5 to 20%. Further, in order to reliably produce particles having a hollow inside (hollow large particles), a foaming agent may be added when obtaining the particles, if necessary, or a polymerization initiator may be added if it includes a polymerization step. Examples include a method of controlling the amount.

When a large amount of the polymerization initiator is added, a gas is generated during suspension, which creates bubbles inside the particles. The addition amount varies depending on the type of the polymerization initiator and cannot be specified unconditionally, but it is generally 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer.
It is desirable that the amount is about parts by weight. If the amount is less than 0.5 part by weight, the gas is not sufficiently generated and the bubbles taken into the toner particles are reduced. If 20 parts by weight or more is added, it will hinder the granulation of toner particles.

As the polymerization initiator used for the polymerization, oil-soluble oxide-based or azo pigment-based initiators usually used in suspension polymerization can be used. For example, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, benzoyl orthochloroperoxide, benzoyl orthomethoxy peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl hydroperoxide. Peroxide initiators such as diisopropylbenzene hydroperoxide, 2,2′-azobisisobutyronitrile, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobis -2,3-Dimethylbutyronitrile, 2,2'-azobis- (2-methylbutyronitrile), 2,2'-azobis-2,3,3-trimethylbutyronitrile, 2,2'-azobis 2-Isopropylbutyronitrile, 1,1'-azobis- (cyclo) Hexane-1-carbonitrile), 2,2'-azobis -
(4-methoxy-2,4-dimethylvaleronitrile), 2
Examples include-(carbamoylazo) isobutyronitrile, 4,4'-azobis-4-cyanovaleric acid and dimethyl-2,2'-azobisisobutyrate.

As a method of incorporating the foaming agent,
For example, the method shown below is preferable.

First, the foaming agent is mixed with the raw material resin of the developing powder and the dye, and then this mixture is suspended in a solvent which dissolves the resin, the dye and the like but does not dissolve the foaming agent. This dispersion is atomized with a sprayer and dried at a temperature at which the foaming agent decomposes or above. As a result, particles having a hollow inside are obtained.

As the foaming agent, those which generate a gas by heating at 100 to 150 ° C. are preferable, and those which sublime in this temperature range are particularly desirable. The type of gas generated is not limited, but it is preferable to use a nontoxic and odorless gas.

The foaming agents that can be used in the present invention are shown below.

For example, urea, oxalic acid, ζ-aminovaleric acid, 2-6-dioxybenzoic acid, 2,4-dioxy-6-methylbenzoic acid, α-camphorcarboxylic acid, sodium hydrogencarbonate, ammonium carbonate, methylmalonic acid. , Asobisisobutyronitrile, benzenesulfonyl hydrazide, diazoaminobenzene, N, N'-dimethyl-N, N '
-Dinitrosoterephthalamide, 4,4'-oxybisbezensulphonyl hydrazide, 4,4'-diphenyldisulphonyl azide and the like.

In the present invention, for example, hollow large particles having at least one bubble inside are produced according to the above method. The hollow form cannot be unconditionally defined in consideration of the particle size of the hollow large particles containing the hollow particles, but in view of the pulverization efficiency, the larger the particle size of the large particles is, the more the bubbles are contained. The particle size of the large hollow particles is not particularly limited, but in order to achieve the above-mentioned object of the present invention, the particle size is at least twice, preferably at least 3 times the particle size of the finally obtained toner particles. It is desirable to do.

Finally, the large hollow particles obtained by the above method are pulverized. The crushing step may be carried out in either a dry method or a wet method, and a conventionally known means such as a jet mill, a hammer mill, a pin mill, a sand grinder or the like can be used. Further, in the present invention, in addition to the above-mentioned pulverizing means, it is possible to pulverize with a stirrer such as an auto homomixer. This is because the particles having a hollow inside are easily pulverized as compared with a kneaded product obtained by usual melt-kneading (having no hollow inside),
This is because it is possible to sufficiently pulverize to a desired particle size with a weak force as compared with the conventional method. In the present invention,
Since it is not necessary to strongly grind as described above at the time of grinding, toner particles having a small amount of fine powder can be obtained, the particle size distribution becomes sharp, and a toner having high classification efficiency (production efficiency) can be obtained. As described below, the average particle size of the toner is 1
The classification efficiency of the toner was evaluated by measuring the volume% of particles having a particle diameter of ½ or less and having a particle diameter twice or more the average particle diameter. Specifically, both the average particle size of the toner is 1/2 or less and the average particle size of the toner is 2% or more.
A toner having a very small amount of fine powder and a small amount of coarse powder can be obtained. Further, when the amount of fine powder or the amount of coarse powder is extremely small, the classification step is not required, so that it is possible to improve the production efficiency and simultaneously simplify the production step.

In the present invention, the additive adhering to the toner surface is removed by friction between the large particles or between the large particles and the crushing device in the crushing step. Further, by pulverizing particles obtained by the wet method to obtain toner particles, a surface on which no polymerization initiator or various additives are adhered appears, which is a problem of the toner usually obtained by the wet method. It is possible to prevent as much as possible the effect of the additives, etc., that adhere to the toner surface, that is, the toner, on the charging property.

The particle size of the toner particles of the present invention is from 2 to 15
μm is preferable, but 3 to 10 μm is particularly useful in the present invention.

A typical example of the dry crushing device is a jet mill. Also in this case, the crushing conditions can be set arbitrarily by appropriately selecting the jet pressure, the collision angle, the collision plate distance, the classification gap, etc., and the toner having the desired particle diameter can be obtained. FIG. 1 is a schematic configuration diagram of a wet crushing device used in the present invention.

After preliminarily mixing the suspension containing large hollow particles obtained by wet granulation in the premix tank 1,
The feed pump 2 sends a predetermined amount into the vessel 3. Ottawa sand is mixed as media 7 in the vessel. As other media, glass beads, ceramic balls and the like can be used. The large hollow particles in the suspension collide with the medium 7 as the disk 4 rotates and pass between the inner wall surface of the vessel and the disk to be crushed. The grinding conditions at this time are adjusted by appropriately selecting the amount of suspension fed into the vessel, the rotation speed of the disk, the distance between the disk and the inner wall surface of the vessel, etc., in accordance with the characteristics of the resin used. . The suspension containing small-sized particles pulverized to a desired particle size is separated from the medium, and then a predetermined amount is sent to the stock tank 6 by the pump 5. Then, the toner particles of the present invention are obtained through a drying step.

The resin which can be used in the toner of the present invention is not particularly limited, but preferably styrene-acrylic resin, styrene resin, (meth) acrylic resin, olefin resin, polyester resin, amide resin, carbonate. Thermoplastic resin such as resin, polyether, polysulfone, etc., or epoxy resin, urea resin,
Thermosetting resins such as urethane resins and their copolymers and polymer blends are used.

Recently, there has been a demand for a technique capable of copying at a higher speed than ever. With regard to the toner used in such a high-speed system, the fixing property of the toner on a transfer paper in a short time,
It is necessary to improve the separability from the fixing roller. Therefore, in order to obtain a toner used in such a high-speed system, a styrene-based monomer as a resin,
(Meth) acrylic monomers, homopolymers or copolymers synthesized from (meth) acrylate monomers,
Or it is desirable to use a polyester resin,
As the molecular weight, the relationship among the number average molecular weight (Mn), the weight average molecular weight (Mw), and the Z average molecular weight (Mz) is 1.0.
00 ≦ Mn ≦ 7,000, 10 ≦ Mw / Mn ≦ 70, 200
It is preferable that ≦ Mz / Mn ≦ 500 and that the number average molecular weight (Mn) is 2,000 ≦ Mn ≦ 7,000. When it is used as an oilless fixing toner, it has a glass transition temperature of 55 to 80.
℃, softening point 80 ~ 150 ℃, 5-20% by weight
It is desirable that the gelling component (1) is contained. Also,
In order to improve the resistance to vinyl chloride, it is desirable to use a polyester resin, and a resin containing a gelling component in an amount of 5 to 20% by weight is particularly desirable.

Further, when a translucent color toner used for OHP or full color is to be obtained, the resin is vinyl chloride resistant, and the adhesiveness to the translucent OHP sheet as the translucent color toner is high. From the viewpoint, it is desirable to use a polyester resin, and in this case, the glass transition temperature is 55 to 70 ° C. and the softening point is 80 to 150.
℃, its number average molecular weight (Mn) 1,000 ~
It is desirable that the linear polyester has a molecular weight distribution (Mw / Mn) of 15,000 or less. Further, a linear urethane-modified polyester obtained by reacting a linear polyester resin with diisocyanate is also suitably used as the binder resin in the case of obtaining a light-transmitting color toner. The linear urethane-modified polyester referred to here is composed of a dicarboxylic acid and a diol and has a number average molecular weight of 2,000 to 1
It is 5,000, and the oxidation is 5 or less.
The main component is a linear urethane-modified polyester resin obtained by reacting 0.95 mol of diisocyanate and having a glass transition temperature of 40 to 80 ° C. and an oxidation of 5 or less. Further, a polymer formed by grafting a styrene-based, acrylic-based, aminoacrylic-based polymer or the like on a linear polyester and copolymerizing it by a method such as block polymerization, and having the same glass transition temperature, softening point, and molecular weight-decreasing properties as described above. Those which have are also suitably used.

The colorant contained in the toner for developing an electrostatic latent image of the present invention is not particularly limited, and various known organic or inorganic pigments and dyes of various colors can be used. Usually, 1 to 20 parts by weight, preferably 2 to 10 parts by weight is used with respect to 100 parts by weight of the above resin. If it is more than 20 parts by weight, the fixing property of the toner will be deteriorated, and if it is less than 1 part by weight, a desired image density cannot be obtained.

The toner of the present invention is preferably post-treated by externally adding inorganic fine particles such as silica, titanium dioxide and alumina in order to impart long-term fluidity and long-term charge stability.

As described above, the toner of the present invention can be efficiently obtained as a toner having a small particle diameter by obtaining hollow particles in the pre-milling stage. Further, the obtained toner is improved in blade cleaning property or charging property as compared with the conventional wet method.

The present invention will be specifically described below with reference to examples.

[0035] Example 1 Component Parts by weight Styrene 100 n-butyl methacrylate 35 methacrylic acid 5 2,2'-azobis (2,4-dimethylvaleronitrile) 3 low-molecular weight polypropylene (Viscol 605P; manufactured by Sanyo Chemical Industries, Ltd.) 3 Carbon black (MA # 8; manufactured by Mitsubishi Kasei Co., Ltd.) 8 Chromium complex salt azo dye (S-34; manufactured by Orient Chemical Industry Co., Ltd.) 3 The above materials were mixed by a sand stirrer to prepare a polymerization composition. The polymerization composition was polymerized in a 3% aqueous solution of gum arabic with a stirrer TK Auto Homomixer (made by Tokushu Kika Kogyo Co., Ltd.) at a rotation speed of 2000 rpm for 6 hours at a temperature of 60 ° C. Were dried to obtain spherical particles having an average particle size of 20 μm. When the cross section of the obtained particles was observed, several hollows of 2 to 3 μm were present inside. Further, the particles were finely pulverized with a jet mill to obtain a toner having an average particle size of 6.1 μm. This is designated as Toner A.

Example 2 In Experimental Example 1, the chromium complex salt dye was replaced with a quaternary ammonium salt (P-51, manufactured by Orient Chemical Industry Co., Ltd.), and the low molecular weight polypropylene was replaced with a low molecular weight polyethylene (High Wax 220P, Mitsui). A toner having an average particle size of 6.0 μm was obtained by the same method as in Experimental Example 1 except that the toner of Petrochemical Industry Co., Ltd. was used. This is designated as Toner B.

Example 3 Spherical particles obtained by the same method as in Experimental Example 1 were crushed in a wet process with a sand grinder (manufactured by Igarashi Machinery Co., Ltd.) and then dried to have an average particle size of 6.2 μm. Toner was obtained. This is designated as toner C.

Example 4 In Example 1, the polymerization initiator 2,2-azobis- (1,
Spherical particles having an average particle size of 20 μm were obtained by the same method as in Experimental Example 1 except that 10 parts by weight of 4-dimethylvaleronitrile) was added.

Observation of the cross section of the obtained particles revealed that bubbles of 2-3 μm were present inside, but the number was about twice that in Experimental Example 1. Further, the particles were finely pulverized with a jet mill to obtain a toner having an average particle size of 5.4 μm. This is designated as toner D.

[0040] Example 5 Component Parts by weight Styrene 100 n-butyl methacrylate 35 methacrylic acid 5 2,2'-azobis (2,4-dimethylvaleronitrile) 3 low-molecular weight polypropylene (Viscol 605P; manufactured by Sanyo Chemical Industries, Ltd.) 3 Carbon black (MA # 8; manufactured by Mitsubishi Kasei Co., Ltd.) 8 The above materials were mixed with a sand stirrer to prepare a polymerization composition. The polymerization composition was polymerized in a 3% aqueous solution of gum arabic with a stirrer TK Auto Homomixer (made by Tokushu Kika Kogyo Co., Ltd.) at a rotation speed of 2000 rpm for 6 hours at a temperature of 60 ° C. Were dried to obtain spherical particles having an average particle size of 20 μm. When the cross section of the obtained particles was observed, several hollows of 2 to 3 μm were present inside.

Separately from this, a salicylic acid metal complex (E-8
4, manufactured by Orient Chemical Industry Co., Ltd.) and hydrophobic titanium oxide
(T-805, manufactured by Nippon Aerosil Co., Ltd.) was previously pulverized in a weight ratio of 1: 1 in a water medium using a sand mill (paint conditioner; manufactured by Red Devil Co.). The resulting metal salicylate complex / titanium oxide mixture was added to the above toner dispersion system in an amount of 1.5 parts by weight based on 100 parts by weight of the toner solid content, and then a Kryptron System (KTM-X type, manufactured by Kawasaki Heavy Industries, Ltd.) 10 Crushing / surface treatment was performed at 1,000 rpm to obtain a toner having an average particle size of 6.1 μm. This is designated as toner E.

Example 6 A solution prepared by dissolving 100 g of a polyester resin (NE-382, manufactured by Kao Corporation) in 400 g of a mixed solvent of methylene chloride / toluene (8/2), 5 g of a phthalocyanine pigment, and a zinc metal complex (E-8).
4, 5 g of Orient Chemical Industry Co., Ltd.) and 5 g of sodium hydrogen carbonate (foaming agent) were placed in a ball mill and mixed and stirred for 3 hours to disperse to obtain a uniform mixed dispersion. Next, as a dispersion stabilizer, 60 g of methylcellulose (Methocel K35LV, Dow Chemical Co.) 4% solution, dioctyl sulfosuccinate soda (Nikkor OTP75, Nikko Chemical Co.) 1% solution 5
g, sodium hexametaphosphate (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.5 g of deionized water in 1000 g of ion-exchanged water, and the above homogenous dispersion was TK Auto Homomixer (manufactured by Tokushu Kika Kogyo).
It was suspended using. The average particle size of suspended particles is 20-2
The rotation speed of the homomixer was adjusted so as to be 5 μm.
Slurry dryer after repeated filtration / washing
(Dispercoat, manufactured by Nisshin Engineering Co., Ltd.), the particles were dried at 120 ° C. to obtain hollow large particles having a particle size of 20 to 25 μm with bubbles inside. This was pulverized with a jet mill to obtain small particles having an average particle diameter of 6 μm. 0.5 parts by weight of a chromium complex salt dye (E-81, manufactured by Orient Chemical Industry Co., Ltd.) was mixed with 100 parts by weight of the obtained small-sized particles, and after sufficiently mixing and stirring, a hybridization system (NHS-O type, Nara Machinery). (Manufactured by Seisakusho Co., Ltd.) was used to perform immobilization at a peripheral speed of 60 m / sec. Furthermore, this particle 1
Henschel mixer was prepared by adding 0.3 parts by weight of hydrophobic silica (H-2000, manufactured by Wacker) and 0.5 parts by weight of hydrophobic titanium oxide (T-805, manufactured by Nippon Aerosil Co., Ltd.) to 00 parts by weight.
Toner F was obtained by treating with (Mitsui Miike Kakoki Co., Ltd.) at 1,000 rpm for 1 minute.

When the cross sections of the toners A to F of the present invention produced by the above method were observed, almost no hollow was observed inside.

Comparative Example 1 Component weight parts Styrene 70 n-Butylmethacrylate 28 Methacrylic acid 22,2-azobis- (2,4-dimethylvaleronitrile) 0.5 (first-class reagent, Wako Pure Chemical Industries, Ltd.) Carbon black (MA # 8; manufactured by Mitsubishi Kasei Co., Ltd.) 8 Chromium complex salt dye (E-81; manufactured by Orient Chemical Co., Ltd.) 3 The above materials were sufficiently mixed with a sand stirrer to prepare a polymerizable composition. This polymerizable composition has a concentration of 3% by weight.
Of the arabic gum aqueous solution, and the number of revolutions is 4,000r with a stirrer TK-auto homomixer (manufactured by Tokushu Kika Kogyo)
After carrying out a polymerization reaction at 60 ° C. for 6 hours while stirring at pm, the temperature was further raised to 90 ° C. to cause a polymerization reaction. After the completion of the reaction, the reaction system was cooled, washed with water 5 times, filtered and dried to obtain spherical particles. The obtained spherical particles were classified by wind force to obtain a black toner having an average particle diameter of 6.0 μm. This is designated as toner F.

[0045] Comparative Example 2 Component Parts by weight Polyester resin (Tafton NE-1110, manufactured by Kao Corporation) 100 Carbon black (MA # 8; Mitsubishi Kasei Corporation) 8 Low molecular weight polypropylene (Viscol 605P; manufactured by Sanyo Chemical Industries, Ltd.) 3 Chromium complex salt type azo dye (S-34; manufactured by Orient Chemical Industry Co., Ltd.) 3 The above materials were thoroughly mixed by a ball mill and then kneaded by a three-roll mill heated to 140 ° C. The resulting mixture was left standing to cool, coarsely pulverized with a feather mill, and then finely pulverized with a jet mill. Then, wind classification is performed, and the average particle size is 6.2.
A black toner of μm was obtained. This is designated as toner G.

[0046] Production Component Parts by weight Porisuteru resin carrier (Tafton NE-1110, manufactured by Kao Corporation) 100 inorganic fine particles (EPT-1000, manufactured by Toda Kogyo) 500 Carbon black (MA♯8, made by Mitsubishi Chemical Industries, Ltd.) 2 After thoroughly mixing and pulverizing the above materials with a Henschel mixer, the cylinder part is 180 ° C and the cylinder head is 170 ° C.
Melt kneading was carried out using the extruder kneader set to. The obtained kneaded product was cooled, coarsely pulverized with a feather mill, finely pulverized with a jet mill, and further classified with an air classifier. A binder type carrier having an average particle diameter of 55 μm was obtained.

Evaluation Toners A to G obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were mixed with the obtained carrier in a toner mixing ratio of 5.0.
% So as to obtain the values of Examples 1 to 5 and Comparative Examples 1 and 2.
To obtain a developer. This is a commercial copying machine EP-5400
Built in (made by Minolta Camera Co., Ltd.), initially after copying 10,000 sheets,
After copying 100,000 sheets, each toner was evaluated according to the following evaluation items. The evaluation results are shown in Table 1.

As is clear from Table 1, it was confirmed that the toner of the present invention is excellent in charging stability and is excellent in cleaning property as compared with the toner prepared by the usual wet granulation method. Further, it was confirmed that the production efficiency is higher than that of the toner obtained by the usual pulverization method.

(1) Particle size measurement The average particle size of toner and carrier is measured by laser diffraction particle size distribution analyzer SALD-1100 (manufactured by Shimadzu Corporation).
Was performed using.

(2) Measurement of Charge Amount 3 g of the developer was sampled, and the charge amount of each toner was measured using the apparatus shown in FIG.

Specifically, each weighed developer 12 is evenly placed on the entire surface of the conductive sleeve 9, and the rotation speed of the magnet roll 10 provided in the conductive sleeve 9 is set to 100 rpm. Set

Then, a bias voltage of 0 to 10 kV is sequentially applied from the bias power source 11, and the potential Vm at the cylindrical electrode 8 at the time when the conductive sleeve 9 is stopped for 5 seconds.
To read. At that time, the weight M of the separated toner 13 adhering to the cylindrical electrode 8 from the conductive sleeve 9 is measured by a precision balance, and the average charge amount of each applied voltage is thus obtained. By totaling these, the charge amount distribution and average charge amount of the toner contained in the developer can be measured.

(3) Cleaning Property After cleaning the surface of the photoconductor with a blade, the image and the photoconductor were visually evaluated. ○ If there is no leftover wipe on the image or on the photoconductor,
When there was some wiping residue on the photoconductor but it did not appear on the image and could be used practically, it was evaluated as Δ, and when the unwiped toner appeared on the image, it was ranked as x.

(4) Particle size distribution In evaluating the particle size distribution of the toner, a measuring device similar to the average particle size measurement is used, and the particle size is ½ or less of the average particle size and 2 or more times the average particle size. The volume% of particles having a particle size is measured and used as the amount of fine powder and the amount of coarse powder, respectively.

The amount of fine powder is preferably 2% or less, but 5% or less is practically usable. The amount of coarse powder is preferably 1% or less, but 5% or less is practically usable.

The production efficiency is calculated by the following formula.

Production efficiency (%) = (toner production amount after classification /
Raw material amount) x 100

[0058]

[Table 1]

[0059]

As described above, in the present invention,
By pulverizing the large particles having a hollow inside obtained by the wet granulation method, it is possible to provide a toner having a small particle size, which is excellent in cleaning property and charging stability and has high production efficiency.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a wet crushing apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram of a charge amount measuring device according to the present invention.

[Explanation of symbols]

 3 Vessel 4 Disk 8 Cylindrical Electrode 9 Conductive Sleeve 10 Magnet Roll 11 Bias Power Supply

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeyuki Shiramoto 2-3-13 Azuchi-cho, Chuo-ku, Osaka Osaka International Building Minolta Camera Co., Ltd.

Claims (1)

[Claims] 1. A toner for developing an electrostatic charge image, which is obtained by granulating hollow particles from a toner composition containing at least a resin and a colorant by a wet method and then crushing the obtained particles.