JPH06313991A - Production of electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To improve a production capacity by using the pulverizing means good in efficiency and to provide the production method of the toner which has fine grain size and is good in fixing property. CONSTITUTION:The pulverizing means of the solidified matter for the toner is provided with (1) the air current classifying machine which has a classifying plate 10 at the base part of a classifying chamber 4, and the powder material supplied with a carrier air is subjected to turning flow and centrifuged to a fine powder and a coarse powder at the classifying chamber by the air current flowing in through a classifying louver 9, and the fine powder is discharged to a fine powder discharging shoot 12 and also the coarse powder is discharged from a discharging port 11, and a powder supplying cylinder 8 having the second-air inlet port 15, a communicating circular guide chamber 5 and plural louver 7 which faces a tip in the tangential direction of an inner peripheral circle direction of the guide chamber 5 at the upper part of the classifying chamber 4, and (2) the pulverizing means communicated with the jet type pulverizer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner used in electrophotography, electrostatic printing, magnetic recording and the like.

[0002]

2. Description of the Related Art As a general method for producing a toner for developing an electrostatic image which requires that the final product be fine particles, a binder resin for fixing the toner on a transfer material, and a tint as a toner are used. Various colorants to be discharged, a charge control agent for imparting an electric charge to particles, and a toner in a so-called one-component developing method as disclosed in JP-A-54-42141 and JP-A-55-18656. Various magnetic materials are used to impart transportability to the product, and if necessary, a release agent and a fluidity-imparting agent are dry-mixed, and then melt-kneaded with a general-purpose kneading device such as a roll mill or extruder. Then, after cooling and solidifying, it is made fine by various crushing devices such as a jet airflow crusher, mechanical impact crusher, etc., and classified by various wind force classifiers, so that the toner has a required particle size.

If necessary, a fluidizing agent, a lubricant, etc. are dry-mixed to obtain a developer. When it is used in a so-called two-component developing method, it is used as an image forming agent after being mixed with various magnetic carriers.

As described above, various crushing devices are used to obtain toner particles which are fine particles. A jet airflow type crusher using a jet airflow is used for crushing toner mainly containing a binder resin. Is preferably used.

Further, these pulverizers are connected to a classifier as shown in the flow chart of FIG. 3, and the pulverized particles are classified into fine particles and coarse particles by the classifier, and the coarse particles are pulverized again. It is used as a pulverizing means for returning to a machine and pulverizing to obtain fine particles as a finely pulverized product.

Conventionally, as a classifier used as the crushing means, a rotor type classifier forcibly creating a swirling airflow by rotation of a classifying blade or a classifier for creating a swirling airflow by an airflow introduced from the outside Although there is a spiral airflow classifier that does this, a spiral airflow classifier having no moving part in the powder contact part is preferably used for classifying toner mainly composed of a binder resin.

As a typical example thereof, a dispersion separator (DS-UR type: manufactured by Nippon Pneumatic Mfg. Co., Ltd.) as shown in FIG. 4 is generally used.

Further, in recent years, generalization of copied materials, printed materials, etc.,
Along with mass consumption, a low cost and high performance developer is required.

For the purpose of high resolution and high definition, there is a demand for a toner having finer particles, and in order to efficiently obtain the toner, Japanese Patent Application Laid-Open No. 1-20715 proposed by the present applicant has been proposed.
The airflow classifiers and the like described in JP-A No. 2 and JP-A-2-303559 are disclosed.

FIG. 5 is a diagram schematically showing an embodiment disclosed in Japanese Patent Laid-Open No. 1-207152.
In FIG. 5, reference numeral 1 denotes a cylindrical main body casing, 2 denotes a lower casing, and a hopper 3 for discharging coarse powder is connected to the lower portion thereof. A classifying chamber 4 is formed inside the main body casing 1, and an annular guide chamber 5 attached to the upper part of the classifying chamber 4 and a conical shape (umbrella shape) having a high central portion
It is closed by the upper cover 6 of.

A plurality of louvers 7 arranged in the circumferential direction are provided on a partition wall between the classifying chamber 4 and the guide chamber 5, and the powder material and air sent into the guide chamber 5 are classified from between the louvers 7 into the classifying chamber. Swirl to 4 for inflow.

The upper part of the guide chamber 5 comprises a space between a conical upper casing 13 and a conical upper cover 6.

A classification louver 9 arranged in the circumferential direction is provided in the lower portion of the main body casing 1, and classification air that causes a swirling flow from the outside to the classification chamber 4 is taken in through the classification louver 9.

At the bottom of the classifying chamber 4, a conical (umbrella) classifying plate 10 having a high central portion is provided, and a coarse powder discharge port 11 is formed on the outer periphery of the classifying plate 10. Further, a fine powder discharging chute 12 is connected to the center of the classifying plate 10 and the chute 12
The lower end of the lower casing 2 is bent into an L shape, and the bent end is positioned outside the side wall of the lower casing 2. Further, the chute is connected to a suction fan via a fine powder collecting means such as a cyclone or a dust collector, and the classification chamber 4 is connected by the suction fan.
A suction force is applied to the louvers 9 to generate a swirling flow required for classification by the suction air flowing into the classification chamber 4 from between the louvers 9.

The airflow classifier has the above-mentioned structure, and is supplied from the supply cylinder 8 into the guide chamber 5 (consisting of powder material pulverized by the jet mill, air used for pulverization, and newly supplied pulverization raw material). When air containing powder material is supplied,
The air containing the powder material passes from the guide chamber 5 between the louvers 7 and swirls into the classification chamber 4 while being dispersed at a uniform concentration.

The powder material flowing into the classifying chamber 4 while swirling flows along with a suction air flow which is generated by a suction fan connected to the fine powder discharging chute 12 and flows between the classification louvers 9 in the lower part of the classifying chamber. The swirling is increased, and the coarse powder and the fine powder are centrifugally separated by the centrifugal force acting on each particle, and the coarse powder swirling around the outer peripheral portion of the classification chamber 4 is discharged from the coarse powder discharge port 11 and discharged from the lower hopper 3. And supplied again to the jet mill.

The fine powder that moves to the central portion along the upper inclined surface of the classifying plate 10 is discharged by the fine powder discharge chute 12.
It is discharged as a finely pulverized product to the fine powder collecting means.

Since all the air flowing into the classifying chamber 4 together with the powder material flows as a swirling flow, the velocity of the particles swirling in the classifying chamber 4 toward the center becomes relatively smaller than the centrifugal force, and the classification is performed. In the chamber 4, classification with a small particle size is performed, and fine powder with a very small particle size can be discharged to the fine powder discharge chute 12. Moreover, since the powder material flows into the classification chamber at a substantially uniform concentration, it is possible to obtain a powder having a fine distribution.

However, in recent years, for the purpose of energy saving, a design has been made in consideration of the fixability of the toner to the transfer support so that the toner is fixed to the transfer support with a small amount of heat when passing through the fixing device. , The chromatogram measured by gel permeation chromatography (GPC) shows a molecular weight of 10 ³ to 2 × 10 ^4.
And a binder resin having at least one peak in each of the molecular weight regions of 5 × 10 ⁵ to 10 ⁷ and having a molecular weight of 10 ⁵ or less on the chromatogram is 75% or more of the total area. The contained toner and the kneaded product cooled and solidified have an MI value of 1 at 125 ° C. under a 10 kg heavy load.
A toner having a value of 0 or more can be used.

The binder resin and toner composition for such a toner are generally soft and have a property that they tend to re-aggregate when miniaturized.

Therefore, in the crushing means using the above classifier, re-aggregation is performed between the supply cylinder 8 where the flow passage cross-sectional area is enlarged and the flow velocity of the air containing the powder material is reduced to the outer peripheral portion of the guide chamber 5. It causes the deterioration of the classification efficiency.

Therefore, the finely pulverized product has a wide particle size distribution range, and as a result, the yield is lowered in the classifying step for removing the fine powder in the next step, and the powder pulverized to a desired particle size or less is used. Since a part of the body is circulated again to the crusher as coarse powder, ultrafine powder (fine powder that is unsuitable as a toner) is likely to be generated. This ultrafine powder is difficult to remove even in the classification process for removing the fine powder because it has a strong attraction to the particles, and when it is used as a toner, a decrease in image density, a fogging phenomenon, an uneven phenomenon on the developing sleeve, and further This causes deterioration of image quality such as cleaning failure when removing the residual toner on the drum.

[0023]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a toner for developing an electrostatic charge image, which solves the above problems.

More specifically, the present invention provides a method for producing a toner having a fine particle size and a good fixing property by improving the production capacity by an efficient grinding means.

[0025]

Means and Actions for Solving the Problems The pulverizing means used in the method for producing a toner for developing an electrostatic charge image of the present invention has an inclined classifying plate having a high central part at the bottom of the classifying chamber, and the classifying The powder material supplied together with the carrier air in the chamber is swirled by the airflow flowing through the classification louver to centrifuge into fine powder and coarse powder, and the fine powder is connected to the outlet provided in the center of the classification plate. A fine powder discharge chute, and an air flow classifier that discharges coarse powder from a discharge port formed on the outer peripheral portion of the classifying plate, the powder supply cylinder having a secondary air inlet at the upper part of the classifying chamber. And an annular guide chamber that communicates with each other, and an air flow classifier and a jet air flow crusher that are provided with a plurality of louvers having their tips directed in the tangential direction of the inner circumference of the guide chamber. Use the one connected as That.

FIG. 3 is a flow chart showing the constitution of the pulverizing means used in the method for producing the toner for developing an electrostatic charge image of the present invention, and FIGS. 1 and 2 show the air flow classifier used in the production method of the present invention. It is the figure which showed one Example schematically.

In FIG. 1, the supply cylinder 8 installed in the upper part of the guide chamber 5 is provided with a secondary air inflow port 15, into which the secondary air is introduced and the conical upper casing 1 is introduced.
By improving the dispersion of the powder material-mixed air from the space between the conical upper cover 6 and the louver 3 through the louvers that are partition walls to the classification chamber 4 and into the classification chamber 4. In addition, it is possible to improve the classification efficiency of toner powder with a small particle size that easily re-aggregates.

Therefore, since finely pulverized products can be obtained as finely divided toner powder from the fine powder discharge chute 12, no ultrafine powder is generated as described above, and when the final product is obtained, good results are obtained. A toner having performance can be obtained.

The above-mentioned secondary air inlet 15 is provided in the supply cylinder 8
Further, the secondary air is provided so as to flow in the traveling direction of the powder material mixed air flowing in the supply cylinder.

The secondary air inlet 15 may be provided as a branch pipe at one or a plurality of locations of the supply cylinder 8,
As shown in FIG. 1, it is preferable that secondary air is introduced from the entire circumference by means such as providing a cylinder outside the supply cylinder 8.

Further, the secondary air inlet 15 is provided with a secondary air amount adjusting means such as a control valve or the like so as not to affect the amount of classification air sucked from between the classification louvers 9 in the lower part of the classification chamber. It is preferable to adjust.

The secondary air is not limited to the system in which the outside air is introduced by suction by the powder material mixed air flow flowing in the supply cylinder, and pressurized air may be introduced.

The coarse powder from the above air stream classifier is finely pulverized by a jet stream pulverizer. An air flow pulverizer using a jet air flow (high pressure gas) is a collision member in which a powder raw material is placed on a jet air flow to form a particle mixed air flow, which is jetted from an outlet of an acceleration tube, and the particle mixed air flow is provided in front of the outlet of the acceleration tube. The powder material is crushed by the impact force.

A known collision type airflow pulverizer is, for example, as shown in FIGS. 6 and 7, and a collision member 36 is provided so as to face the outlet 34 of the accelerating pipe 32 to which the high pressure gas supply nozzle 33 is connected. By the flow of the high pressure gas supplied to the accelerating pipe 32, the powder raw material is sucked into the accelerating pipe 32 from the powder raw material supply port 31 communicating with the middle of the accelerating pipe 32, and the powder raw material is jetted together with the high pressure gas. It collides with the collision surface 37 of the collision member 36, is crushed by the impact, and is discharged from the discharge port 39 to the outside of the crushing chamber.

However, when the collision surface 37 shown in FIG. 7 is perpendicular to the axial direction of the accelerating tube 32, the raw material powder blown out from the jet nozzle 33 and the powder reflected by the collision surface 37 form a collision surface 37. The ratio of coexistence in the vicinity is high, so that the powder concentration in the vicinity of the collision surface 37 is high, and the pulverization efficiency is not good. Furthermore, the primary collision on the collision surface 37 is the main component, and it cannot be said that the secondary collision with the crushing chamber wall 38 is effectively utilized. Further, when the thermoplastic resin is crushed, fusion and agglomerates are likely to occur due to local heat generation at the time of collision, which makes stable operation of the device difficult and causes a decrease in crushing ability.

On the other hand, as shown in FIG. 6, the tip portion of the collision surface 37 of the collision member has a specific conical shape (for example, θ = 1).
60 °) reduces the powder concentration in the vicinity of the collision surface and efficiently collides with the crushing chamber wall 38 to improve the crushing efficiency, which is more suitable for the present invention. is there.

The toner production method of the present invention is designed for the purpose of energy saving in consideration of the fixability of the toner to the transfer support so that the toner is fixed to the transfer support with a small amount of heat when passing through the fixing device. Suitable for the production of toner.

As such a toner, for example, a chromatogram measured by gel permeation chromatography (GPC) has a molecular weight of 10 ³ to 2 × 1.
A binder resin having at least one peak in each of the molecular weight regions of 0 ⁴ and the molecular weight of 5 × 10 ⁵ to 10 ⁷ and having an area of the molecular weight of 10 ⁵ or less on the chromatogram is 75% or more of the entire area. Examples thereof include a toner mainly contained and a toner obtained by cooling and solidifying a kneaded product and having an MI value of 10 or more at 125 ° C. under a heavy load of 10 kg.

Here, the MI value was measured using a melt indexer type L203 (manufactured by Takara Kogyo Co., Ltd.).
The kneaded product is cooled and solidified (coarse crushed product) is used.
A value converted into the extrusion amount [g] per minute is called an MI value.

In order to obtain the binder resin, a method of synthesizing the resin may be devised to obtain a binder having a peak in the above range, or the separately synthesized resins may be blended and used. .

As the monomer constituting the binder resin used in the toner produced by the production method of the present invention, for example, styrene such as styrene, α-methylstyrene, p-chlorostyrene and its substitution products, acryl, and the like. acid,
Methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide A monocarboxylic acid having a double bond such as etc. or a substitution product thereof, for example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate etc. and a substitution product thereof, eg a chloride. Vinyl esters such as vinyl, vinyl acetate, vinyl benzoate, etc., such as vinyl ketones such as vinyl methyl ketone, vinyl excyl ketone, etc., such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether. Vinyl monomers of vinyl ether butadiene, such as are used singly or two or more kinds.

Of these, styrene is the main component because it is relatively easy to design materials and is inexpensive, which satisfies the molecular weight distribution characteristics of the binder resin specified in the present invention. A styrene-based copolymer is preferably used.

In addition to the above binder resin component, the toner used in the present invention may contain the following compounds in a proportion smaller than the content of the binder resin component. For example, silicone resin, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. Is.

The dye / pigment contained in the toner produced by the production method of the present invention includes, for example, carbon black, nigrosine dye, lamp black, Sudan black SM, fast yellow G, benzidine yellow,
Pigment Yellow, India First Orange, Irgadine Red, Paranitroaniline Red, Toluidine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Resor Red 2G, Rake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant Green B, Phthalocyanine Green, Oil Yellow GG,
Zapon First Yellow CGG, Kayaset Y96
3, Kayaset YG, Sumiplast Yellow GG, Zapon Fast Orange RR, Oil Scarlet,
Sumiplast Orange G, Orazol Brown B, Zapon Fast Scarlet CG, Aizenspiron Red BEH, Oil Pink OP, etc. can be applied.

In order to use the toner as a magnetic toner,
Magnetic powder may be contained in the core material. As such a magnetic powder, a substance that is magnetized when placed in a magnetic field is used, and is a powder of a ferromagnetic metal such as iron, cobalt, or nickel.
Alternatively, there are alloys and compounds such as magnetite, hematite, and ferrite. The content of the magnetic powder is preferably 15 to 70% by weight based on the weight of the toner.

Such a magnetic material may be treated with a known coupling agent in order to enhance the compatibility with the resin or the resistance of the toner itself. Examples of such coupling agents include silane coupling agents, titanate coupling agents, aluminum coupling agents, zirconium coupling agents, and the like, and the ratio is 0.1 to 10% by weight with respect to the magnetic material. Good to use in.

Various releasing agents may be used in the toner. Examples of such releasing agents include polyfluorinated ethylene,
Fluororesin, fluorocarbon oil, silicone oil, low molecular weight polyethylene, low molecular weight polypropylene and the like,
0.1 to 20% by weight, preferably 0.
It is used in a proportion of 5 to 10% by weight.

Furthermore, if necessary, an abrasive, a filler,
A fluidity improver, a lubricant, a conductive fine powder and the like may be added, and it is also preferable to add a charge control agent in order to easily charge the toner positively or negatively.

After the above materials are uniformly dispersed by a mixing device such as a Henschel mixer or a super mixer, they are kneaded by a kneading device such as a roll mill or an extruder, cooled, and then ground by a grinding device such as a hammer mill or a speed mill. To obtain a coarsely pulverized product.

After that, the finely pulverized toner is obtained by using the pulverizing means. Further, if necessary, a wind separator such as a micron separator or an elbow jet is used for classification, and the particles are made to have a desired particle size.

If necessary, a fluidity improver such as colloidal silica may be externally added to these toners, and an abrasive such as cerium oxide or strontium titanate or polyvinylidene fluoride or stearic acid may be used. A lubricant such as zinc, carbon black, conductive fine powder such as iron oxide and tin oxide, a charge control agent, and other additives may be externally added and used.

In the present invention, the molecular weight distribution of the resin is GP
C is measured under the following conditions. <GPC measurement conditions for resin> Apparatus: GPC-150C (manufactured by Waters) Column: KF801-7 (manufactured by Showdex) 7 consecutive temperatures: 40 ° C Solvent: THF (tetrahydrofuran) Flow rate: 1.0 ml / min Sample: 0.1m for a sample with a concentration of 0.05-0.6wt%
l injection Measurement is performed under the above conditions, and a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample is used for calculating the molecular weight of the sample.

[0053]

EXAMPLES The basic constitution and features of the present invention have been described above, and the method of the present invention will be specifically described below based on examples. However, this does not limit the embodiments of the present invention in any way.

<Example 1> 100 parts by weight of styrene-n-butyl acrylate copolymer (copolymerization ratio 90:10, peak of GPC measurement: 3.6 × 10 ³ and 8.5 × 10 ⁵ , 1.0) × 10 ⁵ following areas: 85%) magnetic l00 parts by weight of the low molecular weight polypropylene 3 parts chromium complex 1 part by weight the above mixture of monoazo dyes, kneaded at twin-screw kneading extruder heated to 120 ° C., cooled The kneaded product was roughly crushed with a hammer mill to obtain a roughly crushed product (MI value: 21) of 0.1 to 1 mm.

The thus obtained coarsely pulverized product was subjected to the collision type air flow pulverizer shown in FIG. 6 and the air flow classifier shown in FIG. 1 (secondary air inlet 1
No. 5 is a cylinder provided outside the supply cylinder 8 and slits are provided all around the supply cylinder so that the opening cross-sectional area of the secondary air inlet is about 1/10 of the cross-sectional area of the supply cylinder. Secondary air is sucked in and supplied) to a pulverizing means (structure of the flowchart shown in FIG. 3) so that the weight average particle diameter becomes 6.2 μm (measurement by Coulter counter: the same applies hereinafter). Finely ground. The particle size distribution of this finely pulverized product is such that the weight average particle size is 6.2 μm, 4.0 μm or less, the number frequency is 55.6%, and the volume frequency is 10.1 μm or more is 2.7%.
Met.

The finely pulverized product was subjected to removal of fine powder and coarse powder by an elbow jet classifier (manufactured by Nittetsu Mining Co., Ltd.), and the weight average particle diameter was 6.5 μm, 4.0 μm or less, and the number frequency was 19.6.
%, 10.1 μm or more and volume classification 1.5% 7
Obtained in a yield of 5%. Hydrophobic silica 1.0 in this classified product
A toner sample was obtained by externally mixing and mixing wt%.

<Comparative Example 1> The coarsely pulverized product used in Example 1 is a commercially available collision type air flow pulverizer PJM-I type (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) shown in FIG. 7 and a commercially available product shown in FIG. Of air flow classifier DS-UR type (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to give a weight average particle size of 6.2.
Fine pulverization was performed so that the particle size became μm.

The fine pulverization processing amount (= coarse pulverized material supply amount) at this time is about 0.3 times as large as that in Example 1, and when the treatment is continuously performed for 30 minutes or more, the fused material is generated in the pulverizer. It occurred and it became impossible to continue the treatment. Further, the particle size distribution of this finely pulverized product has a weight average particle size of 6.6 μm, 4.0.
The number frequency of particles having a size of μm or less was 64.5% and the frequency of volume of particles having a size of 10.1 μm or more was 9.8%.

Fine powder and coarse powder were removed from this finely pulverized product in the same manner as in Example 1 to give a weight average particle diameter of 6.7 μm and 4.0 μm.
A classified product having a number frequency of m or less of 23.2% and a volume frequency of 10.1 μm or more and 2.2% was obtained with a yield of 57%. To this classified product, 1.0 wt% of hydrophobic silica was externally added and mixed to obtain a toner sample.

<Comparative Example 2> The coarsely pulverized product used in Example 1 was supplied to a pulverizing means comprising a collision type air flow pulverizer shown in FIG. 6 and an air flow classifier shown in FIG. Diameter 6.
Fine pulverization was performed so as to be 2 μm.

At this time, the amount of fine pulverization treatment (= the amount of coarsely pulverized material supplied) was about 0.8 times that in Example 1. The particle size distribution of this finely pulverized product has a weight average particle size of 6.3 μm, 4.
The frequency of number of particles was 0 μm or less, 60.1%, and the frequency of volume of 10.1 μm or more was 4.2%.

Fine powder and coarse powder were removed from this finely pulverized product in the same manner as in Example 1 to give a weight average particle diameter of 6.5 μm and 4.0 μm.
A classified product having a number frequency of m or less of 21.0% and a volume frequency of 10.1 μm or more of 1.8% was obtained with a yield of 68%. To this classified product, 1.0 wt% of hydrophobic silica was externally added and mixed to obtain a toner sample.

The toner samples of Example 1, Comparative Example 1 and Comparative Example 2 were put in a Canon laser beam printer LBP-B406G and a printout test was conducted.

With the toner of Example 1, the image density was 1.40 or more from the initial stage to the toner exhaustion in a normal environment, and stable and very good images such as fine line reproducibility and gradation reproducibility were obtained.

Furthermore, at low temperature and low humidity (15 ° C., 10% R
Even in the continuous printout test in H), there was no charge-up phenomenon, no fog occurred, and the image density and quality were good and stable.

On the other hand, in the toner of Comparative Example 1, in the test under the normal environment, the resolution and halftone were slightly deteriorated near the toner exhaustion. Further, in a test under low temperature and low humidity, the image density decreased with durability, fog became worse, and sleeve ghost was observed.

With the toner of Comparative Example 2, a good image almost equivalent to that of Example 1 was obtained in the test under the normal environment, but fog was slightly worse in the test under the low temperature and low humidity.
Scattering was also seen near the toner exhaustion.

Example 2 100 parts by weight of styrene-n-butyl acrylate copolymer (copolymerization ratio 90:10, peak of GPC measurement: 6.8 × 10 ³ and 1.5 × 10 ⁶ , 1.0) Area of x10 ⁵ or less: 80%) Magnetic material 80 parts by weight Low molecular weight polypropylene 4 parts by weight Chromium complex of monoazo dye 2 parts by weight The above mixture is melt-kneaded by a twin-screw kneading extruder heated to 140 ° C and cooled. The kneaded product was roughly pulverized with a hammer mill to obtain a coarsely pulverized product (MI value: 17) of 0.1 to 1 mm.

The obtained coarsely pulverized product was supplied to the same pulverizing means as in Example 1 and finely pulverized to have a weight average particle diameter of 7.5 μm. The particle size distribution of this finely pulverized product is such that the weight average particle size is 7.5 μm, 4.0 μm or less, the number frequency is 42.2%,
The volume frequency was 12.7 μm or more and 2.7%.

Fine powder and coarse powder were removed from this finely pulverized product in the same manner as in Example 1 to give a weight average particle diameter of 8.4 μm and 4.0 μm.
A classified product having a number frequency of m or less of 9.9% and a volume frequency of 12.7 μm or more of 2.3% was obtained with a yield of 82%. To this classified product, 0.8% by weight of hydrophobic silica was externally added and mixed to obtain a toner sample.

<Comparative Example 3> The coarsely pulverized product used in Example 2 was supplied to the same pulverizing means as in Comparative Example 1, and the weight average particle diameter was 7.5.
Fine pulverization was performed so that the particle size became μm.

At this time, the amount of finely pulverized material (= the amount of coarsely pulverized material supplied) was about 0.5 times that in Example 2. The particle size distribution of this finely pulverized product is such that the weight average particle size is 7.7 μm, 4.0 μm.
The number frequency was 55.6% and the volume frequency was 12.7 μm or more and 5.1%.

Fine powder and coarse powder were removed from this finely pulverized product in the same manner as in Example 1 to give a weight average particle diameter of 8.6 μm and 4.0 μm.
A classified product having a number frequency of m or less of 12.1% and a volume frequency of 12.7 μm or more of 4.2% was obtained with a yield of 62%. To this classified product, 0.8% by weight of hydrophobic silica was externally added and mixed to obtain a toner sample.

<Comparative Example 4> The coarsely pulverized product used in Example 2 was supplied to the same pulverizing means as in Comparative Example 2, and the weight average particle diameter was 7.5.
Fine pulverization was performed so that the particle size became μm.

At this time, the amount of fine pulverization treatment (= the amount of coarsely pulverized material supplied) was about 0.9 times that of Example 2. The particle size distribution of this finely pulverized product is such that the weight average particle size is 7.5 μm, 4.0 μm.
The number frequency was 45.1% and the volume frequency was 12.7 μm or more and 2.9%.

Fine powder and coarse powder were removed from this finely pulverized product in the same manner as in Example 1 to give a weight average particle diameter of 8.4 μm and 4.0 μm.
A classified product having a number frequency of m or less of 10.9% and a volume frequency of 12.7 μm or more of 2.6% was obtained with a yield of 78%. To this classified product, 0.8% by weight of hydrophobic silica was externally added and mixed to obtain a toner sample.

The toner samples of Example 2, Comparative Example 3 and Comparative Example 4 were put in a Canon copying machine NP-6060 to perform a copying test.

When the number of durable sheets was increased to 20,000 in a normal environment, the toner of Example 2 maintained the initial image density of 1.40 within ± 0.05 without any decrease in density during replenishment, resulting in poor cleaning. In contrast, the toner of Comparative Example 3 had an initial image density of 1.20, and the image density increased with the endurance to 1.38 ± 0.07. It has dropped to 1.20 again. In addition, cleaning failure occurred at 15,000 sheets. Further, the toner of Comparative Example 4 also showed a density decrease of 0.10 or more when the toner was replenished.

Further, under low temperature and low humidity, the fog of the toners of Comparative Examples 3 and 4 was worse than that of Example 2.

[0080]

As described above, by using the toner production method of the present invention, even in the production of a soft toner having a fine particle diameter, the image density is high and the stability and the durability are good as compared with the conventional method. It is possible to obtain an excellent toner having no image defects such as fogging, scattering, and poor cleaning at low cost.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of a classifier used in the fine method of the present invention.

2 is a cross-sectional view taken along the line A-A ′ of FIG. 1 (and FIG. 5).

FIG. 3 is a flowchart showing a configuration of a crushing means used in the manufacturing method of the present invention.

FIG. 4 is a schematic sectional view of a conventional classifier.

FIG. 5 is a schematic sectional view of a conventional classifier.

FIG. 6 is a schematic cross-sectional view of a collision type airflow crusher used in an example.

FIG. 7 is a schematic cross-sectional view of a collision type airflow crusher used in a comparative example.

[Explanation of symbols]

 4 Classification room 5 Guide room 7 Louver 8 Supply cylinder 10 Classification louver 15 Secondary air inlet 33 Ground air supply port 37 Collision plate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location B02C 23/30 7112-4D B07B 7/08 (72) Inventor Shunji Suzuki 3-chome Shimomaruko, Ota-ku, Tokyo No. 30-2 Canon Inc. (72) Inventor Manabu Ono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. A method for producing a toner in which a composition containing at least a binder resin and a colorant is melt-kneaded, the kneaded product is cooled and solidified, and the solidified product is pulverized by a pulverizing means to obtain a toner. It has an inclined classifying plate having a high central portion, and the powder material supplied together with the conveying air in the classifying chamber is swirled by the airflow flowing through the classifying louver to be centrifugally separated into fine powder and coarse powder. An air flow classifier for discharging fine powder to a fine powder discharge chute connected to a discharge port provided at the center of the classifying plate and discharging coarse powder from a discharge port formed on the outer peripheral part of the classifying plate. A powder supply cylinder having a secondary air inlet in the upper part of the chamber;
An annular guide chamber is provided in communication with the air flow classifier provided with a plurality of louvers having its tip oriented in the tangential direction of the inner circumferential direction of the guide chamber, and a crushing means for communicating the jet air flow crusher with each other. A method for producing a toner for developing an electrostatic image, which is characterized. 2. The chromatogram measured by gel permeation chromatography has a molecular weight of 10 ³
In each of the molecular weight region of to 2 × 10 ⁴ and a molecular weight of 5 × 10 ⁵ to 10 ^7, it has at least one peak, a molecular weight of 10 ⁵ or less of the area of the chromatogram is more than 75% of the total area forming The method for producing a toner for developing an electrostatic charge image according to claim 1, characterized in that the toner mainly contains a coating resin. 3. A kneaded product obtained by cooling and solidifying at 125 ° C.,
The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the MI value under a heavy load of 10 kg is 10 or more.