JPH09258487A - Electrophotographic color toner and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elecrophotographic color toner having uniform and fine dispersion of a coloring agent in an almost primary particle state in a binder resin. SOLUTION: In the production of an electrophotographic color toner containing a binder resin and a coloring agent, a water-contg. paste coloring material in a wet cake state is used as the coloring agent, and a higher alcohol is added as a dispersant if necessary. Then the toner source material is fused and kneaded in a fusing and kneading machine equipped with plural numbers of rotary kneading screws in different directions and a cooling means for the inner wall of the chamber and/or kneading screws.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color toner for electrophotography and a method for producing the same, and more particularly to a color toner for electrophotography having an improved dispersibility of a colorant.

[0002]

2. Description of the Related Art An electrophotographic toner (hereinafter abbreviated as a toner) is prepared by mixing a binder resin, a colorant, a release agent, a charge control agent, etc., if necessary, melt-kneading, cooling and solidifying, crushing, Obtained by classifying. Further, if necessary, a fluidity-imparting agent, a charge control agent, a cleaning aid, a transfer aid, etc. are adhered and fixed on the toner surface, and coarse powder is removed by sieving,
After classification, spheronizing treatment is applied to reduce the adhesion of toner,
In some cases, the powder fluidity, developability and transferability are improved.

In the toner, it is essential that components such as a colorant, a release agent and a charge control agent are uniformly and finely dispersed in the binder resin.
In order to achieve high image quality, it is particularly important to make the colorant highly dispersed. On the other hand, the mixing degree and dispersibility of the colorant inside the toner are substantially determined under the melt-kneading conditions in the toner manufacturing process.

For example, when the colorant is unevenly distributed in the binder resin, or when the colorant is uniformly dispersed but the dispersion unit is large, a step after the melt kneading, that is, a pulverizing step,
Since the toner is pulverized while the colorant is unevenly distributed or the dispersion unit is large, a toner having a non-uniform composition is produced. In particular, when the dispersion is remarkably poor, only a single component or particles having an uneven composition are mixed in the toner, which may lead to a broad charge amount distribution or even reverse polarity. Further, if the colorant is exposed on the surface of the toner or is liberated to be finely divided, the powder fluidity of the toner is remarkably lowered, which may cause filming on the photosensitive material.

For example, in the case of a color material whose particle components are used in full color, the desired color cannot be obtained and the desired color cannot be obtained because the transparency is lowered and the superposed base color does not appear. The color gamut becomes narrow, which causes a decrease in saturation, a decrease in coloring power, a decrease in density, and a decrease in graininess. In addition, a large difference in charge amount may occur between the colors of yellow, magenta, and cyan, resulting in poor color reproducibility.
Further, the strength of the binder may vary and the strength may be lowered, resulting in an adverse effect on the fixing property. Further, since the particle size distribution in the pulverizing process is likely to be broad and the charge distribution is very broad, fog in the background and stains in the machine are likely to occur, and the life of the toner is shortened.

Further, even when the particle component is a two-component black toner, the uneven distribution of the composition may not provide a sufficient amount of charge, resulting in a very broad charge distribution.
Poor admix, fog, and dirt inside the machine.
Further, when the colorant is magnetic powder, the magnetic powder is released from the aggregate of magnetic powder and the unevenly distributed portion of the magnetic powder, and the surface of the photoconductor is scratched in the copying machine or is retained on the developer carrier. It may be accumulated as it is, causing defects such as gradually causing uneven density.

Recently, high quality, high reliability and high speed have been demanded in all of copying machines and printers, and as a result, smaller particle size and sharper particle size distribution have been required for toner. It became so. When the toner has a smaller particle size, the dispersion unit of each component, the uniformity, and the sharpness of the particle size distribution are required to be even better than those of the conventional toner. If possible 1
It becomes necessary to disperse the particles up to the vicinity of the secondary particles.

By the way, as a kneading device for dispersing the colorant or the like in the binder resin, a Banbury mixer, a pressure kneader, an extruder or the like is generally used. It is equipped with two or more rotating shafts (screws, rotors, rolls, etc.), but continuous screw type kneaders (extruders) are mainly used from the viewpoint of continuous productivity (high productivity, low cost). ing.

Usually, a continuous screw type kneading machine used for producing toner is composed of a feed screw part for mainly feeding raw materials and a kneading part for mainly kneading.
The screw shafts of the book pass through them. Then, the periphery thereof is surrounded by a cylindrical inner wall called a barrel or a chamber. The barrel can be heated and cooled by a heater, water, oil, etc., and the screw and the chamber can be cooled by water, etc. The screw is divided into a same-direction rotating type and a different-direction rotating type, and the type of the barrel, the chamber, the shape of the screw, etc. are properly used according to the purpose.

However, the raw materials are melted at the temperature of the barrel,
When a melt kneader of the type in which the screw rotation is performed in the same direction is used, the viscosity of the raw material is generally too low, a high share cannot be given to the toner raw material, and the desired high dispersion is obtained. I can't get it. A method of adding water during kneading has been proposed as one of methods for increasing the viscosity of raw materials to obtain a high share (Japanese Patent Laid-Open No. 61-5062).
4 gazette). According to this method, the resin temperature during kneading can be lowered by about 10 to 60 ° F (about 5.6 to about 33.3 ° C), and as a result, the dispersion of the colorant can be made finer than before. You can, but you can't yet make it fine enough. On the other hand, a chamber cooling system, a screw different rotation type raw material self-heating type kneader can significantly improve the dispersion of the colorant as compared with the barrel type heating kneader equipped with the above-mentioned same direction rotating type screw. .

In the chamber-cooled type, screw different-direction rotation type raw material self-heating type kneader, the toner raw material is
It is supplied from the feed port and sent to the kneading section by the feed screw. The kneading section consists of a feed vane that tries to send the raw material to the discharge side and a return vane that tries to return the raw material, and due to this pressure to try to return and shear in the clearance part of the kneading screw and the chamber, the raw material has a high share. Can be added, self-heating, melting and kneading are performed, and then discharged. The kneading temperature at this time has a great influence on the dispersion quality of the colorant and the release material in the toner.

That is, when the kneading temperature is high, the viscosity of the raw material becomes too low to apply sufficient shear, and the dispersion unit of the colorant or the like cannot be reduced. Further, if the kneading temperature is too low, the wettability of the binder resin is deteriorated, so that the coloring agent or the like cannot be sufficiently wetted, and as a result, the aggregate remains as it is, or is unevenly distributed in the binder resin. It will be discharged from the kneader. Therefore, in a chamber-cooled, screw counter-rotating raw material self-heating type kneader, it is necessary to perform kneading at an optimum kneading temperature in order to form a predetermined dispersion unit with high dispersion. .

The kneading temperature is conventionally adjusted by adjusting the screw rotation speed, kneading time (supply amount) of raw materials, cooling water flow rate and cooling temperature, and adding water during kneading (Japanese Patent Laid-Open No. 61-50624). No. gazette) has been used. In the conventional toner, by using this chamber cooling type screw different rotation raw material self-heating type kneader, it is possible to obtain high dispersibility in dispersing the colorant and the like which cannot be obtained by other kneaders. It was

However, in order to meet the recent demands for full color and high image quality, it is desired that the dispersion of the colorant be in a state close to that of the primary particles, and that the particle size is smaller and the dispersion is dispersed. Type (large surface area) colorants are beginning to be used, but using the chamber cooling type screw counter-rotating raw material self-heating type kneader that can obtain the highest dispersion among existing kneaders Even if the resin temperature during kneading is adjusted as described above, it was impossible to disperse the colorant, particularly the pigment, in the vicinity of the primary particles.

In order to disperse the target particles in the vicinity of the intended primary particles using the above colorant, for example, a flushing colorant is used, master batch kneading is carried out, or a dispersant is added together with the raw materials. Although it has been proposed, there is no case in which it is dispersed to the vicinity of the primary particles. Further, use of a flushing coloring material, masterbatch kneading, or multi-order kneading has drawbacks that the raw material cost rises, the kneading equipment becomes complicated, and the production cost rises.

Various dispersants have been proposed in the past, but any of the dispersants proposed so far has an adverse effect on the charging characteristics, or in full color,
Not only is the color characteristics impaired, but the target dispersion has not been sufficiently secured. For example, when a phthalocyanine derivative is added as a dispersion aid, the dispersion of the pigment is slightly improved, but it cannot be dispersed up to the vicinity of the primary particles, and furthermore, the coloring property of the colorant to be used is impaired, resulting in color reproduction. It narrows the area and causes a decrease in saturation. (JP-A-4-186370) As described above, in the melt-kneading step, dispersing the disperse-dispersion type colorant to the vicinity of the primary particles is a conventional kneading technique, particularly a kneading technique for the purpose of high dispersion. It was in a very difficult situation.

[0017]

SUMMARY OF THE INVENTION The present invention solves the above problems and provides a color toner for electrophotography which enables a colorant to be uniformly and finely dispersed in the binder resin to the vicinity of primary particles. It is intended to provide a manufacturing method. Also,
An object of the present invention is to provide a color toner for electrophotography which enables formation of a color image having a stable density and does not damage the photoconductor.

[0018]

Means for Solving the Problems The inventors of the present invention have earnestly studied a method for producing an electrophotographic color toner in which a colorant is uniformly and finely dispersed in a binder resin up to the vicinity of primary particles, and as a result, as a result, When a toner raw material is melt-kneaded by a melt-kneader equipped with a plurality of kneading screws rotating in parallel, and a means for cooling the chamber inner wall and / or the kneading screw, a wet cake-like water content is used as a colorant. It has been found that the use of a paste coloring material makes it possible to uniformly and finely disperse the above colorant, and succeeded in completing the present invention. That is, the configuration of the present invention is as follows.

(1) In a method for producing an electrophotographic toner containing at least a binder resin and a colorant, a wet cake-like water-containing paste colorant is used as the colorant, and a plurality of kneadings rotating in different directions are used. Equipped with a screw,
A method for producing an electrophotographic toner, which comprises melt-kneading a toner raw material with a melt-kneader equipped with a means for cooling the inner wall of the chamber and / or the kneading screw.

(2) The electrophotographic photograph according to (1), wherein the melt-kneading machine is kneaded by adjusting the shear rate γ [sec ^-1 ] defined by the following formula within a range of 200 to 1200. Of manufacturing toner for toner. Shear rate γ [sec ^-1 ] = (π × D × N) ÷ (h × 6
0) where π = circular ratio, D = screw diameter [mm], N =
Screw rotation speed [rpm], h = clearance between screw and barrel [mm]

(3) The electrophotographic toner according to (2) above, wherein the melt-kneader is kneaded by adjusting the shear strain (S) defined by the following formula in the range of 5,000 to 30,000. Production method. S = shear rate γ [sec ^-1 ] × kneading time [sec]

(4) The water content of the water-containing paste is 50 to 9
The method for producing an electrophotographic toner according to any one of the above (1) to (3), characterized in that a coloring agent is used in an amount of 0% by weight.

(5) In any one of the above (1) to (4), a higher alcohol represented by the following general formula is added as a dispersing aid for the colorant, and the mixture is melt-kneaded. A method for producing the electrophotographic toner described above. _{Formula: CH 3 (CH 2) X} CH 2 OH (X 28
~ 48 integer)

(6) The higher alcohol has a volume average diameter of 4 to
The method for producing a toner for electrophotography according to the above (5), which is used in the range of 20 μm.

(7) The higher alcohol is added in the range of 0.1 to 20.0 parts by weight to 100 parts by weight of all components of the toner, preferably the amount of colorant (the amount of colorant in the water-containing paste). Where A is 0.2, the higher alcohol is 0.2
A to 2.0 A is added in the range above
(5) The method for producing the electrophotographic toner according to any one of (6) to (6).

(8) An electrophotographic toner manufactured by the manufacturing method described in any one of (1) to (7) above.

[0027]

FIG. 1 shows a melt-kneader used in the present invention, which comprises a plurality of kneading screws rotating in different directions and a cooling means for the inner wall of the chamber and / or the kneading screw. FIG. The kneading screw consists of a screw part that conveys the raw materials to the discharge side and a kneading part that mainly mixes the raw materials with a strong shearing force, and uses two or more of them in combination to rotate in different directions. Let me use it. The screw part is a blade (feed blade) that tries to send the raw material to the discharge side.
The kneading part is composed of a wing (return wing) for returning the raw material, and the circumference thereof is surrounded by a cylindrical inner wall called a chamber. There is a gap called a tip clearance portion between the kneading screw of the kneading portion and the chamber. Then, water, brine, cooling water, or the like is caused to flow inside the kneading screw and inside the chamber to cool the melted raw material.

The toner raw material is supplied from the feed port and sent to the kneading section by the feed blade of the screw section. In the tip clearance part of the kneading part, it receives a strong returning pressure by the returning blade and a strong shearing force due to the rotation of the kneading screw. While being fed from the screw section to the kneading section, the raw materials are kneaded by the return blade from the latter half of the feed blade, self-heated and melted. Further, the colorant and the like are uniformly and finely dispersed by being strongly sheared by the screw rotation in the tip clearance portion. However, using only the conventional kneading screw which rotates in the opposite direction and the inner wall of the chamber and / or the kneading screw provided with the cooling means, only the melt kneader is used.
The colorant cannot be dispersed in the vicinity of the primary particles.
It is also possible to provide a vent port in front of the kneading portion to remove air in the toner raw material to increase the filling rate. The high fill rate makes shearing in the kneading area more effective and prevents feed necks.

The present invention succeeds in securing excellent dispersibility by using the above-mentioned kneader and the wet cake-like water-containing paste coloring material before drying as the coloring agent. Conventionally, after purifying the pigment, filtration,
Although dry powder colorants have been used, once dried pigments have strong adhesion and cohesive force between pigment particles, so it is not possible to disperse them to the vicinity of the primary particles with a kneader in the toner manufacturing process. It was possible. However, when the wet cake-like water-containing paste coloring material is used, it is possible to disperse the particles up to the vicinity of the primary particles with a kneading machine of a counter-rotating kneading screw and a chamber kneading screw cooling type.

Since water is present between the colorant particles, the colorant particles are prevented from being strongly aggregated, and since the water-containing paste is used, the temperature rise of the kneading resin is suppressed and the kneading is performed. Moisture evaporates therein to increase the filling rate in the kneader and increase the probability of contact with the inner wall of the cooling chamber, so that cooling can be performed with high efficiency. As a result, it is presumed that a sufficiently high share can be given to the molten raw material and dispersion up to the vicinity of the primary particles has become possible. Furthermore, in the small area of the chip clearance, the amount of heat exchange with the chamber is high and cooling is promoted, so the viscosity of the binder resin becomes high, and as a result, it is possible to give a high share to the raw material. Be done.

The water content of the water-containing paste coloring material used here is in the range of 50 to 90% by weight, preferably 60 to 80.
A weight percent range is suitable. When the water content exceeds 90% by weight, it depends on the pigment content in the toner, but it adheres violently inside the mixer when mixing the raw materials, and also adheres to the feed screw part of the kneader to knead the raw materials. Can not be sent to. Also, the water content is 50% by weight.
If the amount is smaller, the number of particles without water between the pigment particles increases, and the resin temperature during kneading cannot be lowered sufficiently.

Further, in the present invention, a higher alcohol is added as a dispersant at the time of mixing the raw materials to enable finer dispersion, and the particle diameter of the higher alcohol to be added is particularly in the range of 4 to 20 μm in volume average diameter. , Preferably 5
When it is in the range of 9 μm, the dispersion is almost in the dispersed state of primary particles. If the raw materials and higher alcohol are mixed in advance before kneading, the adhesion of colorant particles to each other is suppressed, and the dispersibility (compatibility) of the higher alcohol and the binder resin during melt-kneading
It is presumed that the colorant can be dispersed as described above by the dispersive power of the higher alcohol.
If the volume average diameter of the higher alcohol exceeds 20 μm, the above-mentioned dispersibility cannot be exerted, and if it is smaller than 4 μm, aggregation among the higher alcohol particles is likely to occur and the dispersibility is likely to deteriorate.

For adjusting the particle size of the higher alcohol, a general mechanical crusher, a jet crusher or the like can be used. Further, these may be classified by an inertial classifier, a centrifugal classifier or the like to adjust the amounts of fine powder and coarse powder. In the present invention, the amount of higher alcohol added is 100% of the total toner composition.
A suitable range is 0.1 to 20.0 parts by weight, preferably 0.2 to 10.0 parts by weight, based on parts by weight.

As the higher alcohol of the present invention, those represented by the following general formula are used. CH ₃ (CH ₂ ) _X CH ₂ OH (where X is 28 to 48)
When X is more than 48, the desired level of colorant dispersion cannot be maintained, and when it is less than 28, filming on the photoreceptor is likely to occur. Unlike the other dispersants, the higher alcohols do not broaden the charge distribution, widen the toner particle size distribution, impair the powder fluidity, or impair the color characteristics.

The diameter D of the kneading screw of the kneading machine of the present invention is generally determined by the production scale, and
When the total screw length is M, the length L of the kneading part is L = 0.2 in order to apply and disperse the desired shearing force.
It is necessary to be in the range of M to 0.9M, preferably 0.4M to 0.8M. If it exceeds 0.9 M, the length of the raw material feed screw portion becomes short, so that the ability to feed the raw material to the kneading portion becomes insufficient, and clogging (feed neck) of the supply portion occurs, which is not preferable. 0.2
If it is less than M, the shearing time becomes short, and the desired high dispersion cannot be obtained.

The ratio of the length of the kneading portion of the screw of the kneading machine of the present invention to the diameter of the kneading screw is L
/ D = 3 to 8 is set, and preferably 4 to 6 is set. That is, when L / D is less than 3, kneading time is shortened, and when L / D is greater than 8, feed neck is likely to occur. Further, the kneading part has a feed blade and a return blade, but the length ratio of the feed blade and the return blade is 0.5 to 2.0 when the feed blade is 1.
And the range of 0.75 to 1.5 is preferably used.

As the kneading screw of the kneading machine of the present invention, a twin blade type is mainly used. In addition, the ratio of the length from the center of the ridge of the wing to the center of the abdomen (see FIG. 4) is in the range of 0.3 to 0.8, preferably 0.5 to 0.8 for the abdomen when the ridge is 1.
Those having a range of 0.75 have a great effect on the dispersion of the pigment up to the vicinity of the primary particles.

In the present invention, the shear rate γ represented by the following equation
It is preferable to select the screw rotation speed so that [sec ⁻¹ ] is in the range of 200 ≦ γ ≦ 1200, preferably 500 ≦ γ ≦ 900. Shear rate γ [sec ^-1 ] = (π × D × N) ÷ (h × 6
0) where π = circular ratio, D = screw diameter [mm], N =
Screw rotation speed [rpm], h = clearance between screw and barrel [mm].

Further, in the present invention, it is desirable that the shear strain (S) represented by the following equation is kneaded so as to be in the range of 5000 ≦ S ≦ 30000, preferably 7000 ≦ S ≦ 18000. S = shear rate γ [sec ⁻¹ ] × kneading time [sec] Here, the kneading time means the residence time of the raw material in the kneading screw part.

As the binder resin used in the toner of the present invention, a conventional thermoplastic resin for the binder resin of the toner can be used. Specifically, styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate and acrylic acid. Α-methylene aliphatic monocarboxylic acid esters such as ethyl, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl ethyl ether, Vinyl ethers such as vinyl methyl ether and vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone; homopolymers or copolymers thereof can be exemplified, and particularly The Table of the binder resin include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, a styrene-acrylonitrile copolymer, styrene
Examples thereof include butadiene copolymer, styrene / maleic anhydride copolymer, polyethylene and polypropylene. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, parafein wax and the like can be mentioned. As the above-mentioned binder resin, it is preferable to use a binder resin having a structure and a molecular weight in which the melting temperature is in the range of 80 ° C to 150 ° C. Especially,
Styrene / acrylic resin or polyester resin is preferable.

The melting temperature is the flow tester CFT-50.
A temperature-apparent viscosity curve was obtained using a 0F type (manufactured by Shimadzu Corporation), and the melt viscosity was 1 × 10 ⁴ Pa on the viscosity curve.
-The temperature at the time of s was made into the melting temperature. Melt viscosity measurement conditions Temperature rising rate 3.0 ° C / min Start temperature 80.0 ° C Ultimate temperature 150.0 ° C Measurement interval 3.0 seconds Preheating time 300.0 seconds Cylinder pressure 10.0 kgf / cm ² Die hole diameter 1.0 mm Die length 1.0 mm

A releasing agent may be added to the color toner of the present invention in order to prevent fixing offset. Adding a release agent does not hinder the dispersion of the colorant,
Also, the dispersion itself of the release agent can be made very fine. The release agent added is 100 parts by weight of the toner,
It is in the range of 1 to 10 parts by weight, preferably 3 to 7 parts by weight. The release agent may have a particle size of 2 mm or less, preferably 100 μm to 1 mm.

As the release agent, paraffins having 8 or more carbon atoms, polyolefins and the like are preferable, and examples thereof include paraffin wax, paraffin latex, microcrystalline wax, low molecular weight polypropylene and low molecular weight polyethylene, which may be used alone or in combination. Can be used. The preferable range of the softening point is 110 to 150 ° C. In the present invention, when two or more releasing agents are used, it is preferable to adjust / set the temperature for the releasing agent having the lowest softening point. The softening point is measured according to JISK-22.
According to the 07 softening point test method (ring and ball method).

As the colorant for the toner, known colorants such as phthalocyanine copper cyan colorant, azo yellow colorant, azo magenta colorant, quinacridone magenta colorant can be used. Specifically, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow,
Methylene Blue Chloride, Phthalocyanine Blue, Malachite Green Oxalate, Lamp Black, Rose Bengal, CI Pigment Red 48: 1, CI Pigment Red 12: 2, CI Pigment Red 57: 1, CI Pigment Yellow 97, CI Pigment Yellow Yellow 12,
CI Pigment Blue 15: 1, CI Pigment Blue
A water-containing paste such as 15: 3 can be exemplified as a typical one.

A charge control agent can be added to the toner of the present invention, if necessary. As the charge control agent, a fluorine-based surfactant, a salicylic acid metal complex, a metal-containing dye such as an azo metal compound, a polymer acid such as a copolymer containing maleic acid as a monomer component, a quaternary ammonium salt, An azine dye such as nigrosine can be added.

In the present invention, the binder resin, the colorant, and if necessary, the higher alcohol, the release agent and the charge control agent are premixed with a mixer or the like, and then kneaded, rolled, cooled, crushed, crushed, etc. The toner is obtained by classifying through the steps. Rolling is in the rubber industry,
A roll type that is usually used in the toner industry can be used, and a type that cools the roll with cooling water, water, brine or the like is suitable from the viewpoint of adhesion and dispersion. The thickness of the rolled slab varies depending on the production scale, but is generally adjusted to 1 to 20 mm by a roll gap or the like. For cooling the kneading slab, a type of applying cooling air, a type of immersing in cooling water for cooling, a type of cooling the upper and lower surfaces of the belt for sandwiching and rolling the slab with cooling water and the like are used. The latter is particularly suitable from the viewpoint of dispersion of the release agent.

For crushing, a normal crusher such as a jet crusher or a mechanical crusher can be used, and a collision mechanism may be provided inside, or a closed circuit may be formed by coarse powder classification or the like. . For classification, a centrifugal classifier or an inertial classifier can also be used. The toner particles are 3-1 by pulverization and classification.
The volume average particle diameter is adjusted to 5 μm, preferably 5 to 12 μm.

Further, in the present invention, for the purpose of improving flow characteristics, controlling charge, improving developing / transferring property, etc., after finely classifying toner particles, inorganic fine powder such as titania, silica, alumina, etc. may be added and mixed. Good. The surfaces of titania, silica, alumina, etc. are silane coupling agents, surfactants, 4
It may be treated with a graded ammonium salt or the like. In addition, if necessary, a substance such as tin oxide for the purpose of improving charge exchange, or
Large particle size silica, titania, etc. may be added only for the purpose of improving transferability and developability. Further, a cleaning aid such as polystyrene fine particles, polymethylmethacrylate fine particles, or polyvinylidene fluoride fine particles may be added.

As the mixer used in the present invention, for example, an ordinary mixer such as a V-type blender, a Henschel mixer, a Loedige mixer or the like can be used. Also,
In the present invention, a sieving step may be provided to remove coarse powder. Examples of the sieving machine include a gyro shifter, an electric sieving machine, and a high boulder.

The electrophotographic color toner of the present invention can be used as a non-magnetic one-component developer containing no magnetic powder or as a magnetic two-component developer using a carrier. As a carrier when used as a two-component developer, iron powder, glass beads, ferrite powder, nickel powder, magnetite powder, or those with a resin coating on their surface, or a resin and a charge control agent A resin-dispersed carrier obtained by kneading with a magnetic material, pulverizing, and classifying can be used.

[0051]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. The particle size distributions of the toner and higher alcohol in the examples and comparative examples were measured using Coulter Multisizer II manufactured by Coulter Electronics.

Example 1 Binder resin: Polyester resin 94 parts by weight (Mw = 25,000, Tg = 66 ° C., melting temperature = 102 ° C.) Magenta (RED122) water-containing paste pigment 30 parts by weight (primary particle diameter) = 0.02 μm, water content 80% (water 24 parts by weight)) The above composition was mixed and stirred with a 150 liter Henschel Kimisa (Mitsui Miike Koki Co., Ltd.) to prepare a kneading material. Next, this kneading material was continuously kneaded with a screw in different directions, a chamber cooling type raw material self-heating type continuous kneader (D = 5 cm, L = 25 cm, M = 36 cm, h (clearance) = 3 mm, Blade / Feeder) length ratio =
1.0, wing (peak / abdomen) ratio = 0.7, shear rate γ
= 800, shear strain S = 14400). The temperature of the kneaded material at the discharge port at this time was 123.
The heat exchange amount with the chamber per unit weight of the raw material at ℃ was 6.4 × 10 ⁵ J / kg.

The resulting kneaded product was pressure-cooled with a water-cooling type cooling conveyor, pulverized with a jet mill, and classified with a centrifugal classifier to obtain toner particles having a volume average particle size of 6.5 μm. To 100 parts by weight of the toner particles, 1.0 part by weight of anatase-type titania treated with decyltrimethoxysilane having an average particle diameter of 12 nm as an external additive and silica treated with hexamethyldisilazane having an average particle diameter of 60 nm are used. 1.0 part by weight of was added and mixed for 5 minutes with a 5 liter Hekin shell mixer to obtain a toner.

Example 2 In Example 1, 6 parts by weight of a higher alcohol having a volume average diameter of 30 μm represented by the following structural formula was added to 100 parts by weight of a pigment as a colorant, and 88 parts by weight of a binder resin. A toner was manufactured under the same manufacturing conditions and with the same composition as in Example 1, except that the parts were changed. The structural _{formula: (CH 3 (CH 2)} 35 CH 2 OH)

Example 3 A toner having the same composition and the same manufacturing conditions as in Example 2 was prepared, except that the volume average diameter of the added higher alcohol in Example 2 was changed to 5 μm.

[Comparative Example 1] The same composition and the same production conditions as in Example 3 were used except that the twin-screw extruder (manufactured by Toshiba Machine Co .: TEM50, screw rotating in the same direction) was used as the melt-kneader in Example 3. To prepare a toner. At this time, the barrel set temperature was 120 ° C and the kneading temperature was 128 ° C.

Comparative Example 2 Binder resin: polyester resin 93.7 parts by weight (Mw = 25,000, Tg = 61 ° C.) Magenta (RED122) water-containing paste pigment 9 parts by weight (primary particle diameter = 0.02 μm) Moisture content = 30% (water: 2.7 parts by weight) A toner was prepared using the above composition under exactly the same manufacturing conditions and the same external additive composition.

Comparative Example 3 Example 1 was repeated except that 6 parts by weight of magenta (RED122) dry pigment was used as the colorant and the binder resin was changed to 94 parts by weight.
A toner was manufactured under exactly the same manufacturing conditions.

Example 4 Binder resin: Styrene / acrylic copolymer 91% by weight (copolymerization ratio 80/20, Mw = 100,000, Tg = 60 ° C.) Sian (Blue 15: 3) water-containing paste pigment 10 Parts by weight (primary particle diameter = 0.02 μm, water content = 70% (7 parts by weight of water) polypropylene wax (volume average diameter 500 μm) 3 parts by weight higher alcohol (volume average diameter 18 μm) 3 parts by weight [structural formula: ( CH ₃ (CH ₂ ) ₃₂ CH ₂ OH)]

The above composition was mixed and stirred, and then melt-kneaded in the same manner using the kneading machine used in Example 1. The temperature of the kneaded material at the discharge port at this time was 121 ° C. The resulting kneaded product was pressure-cooled with a water-cooling type cooling conveyor, and then pulverized and classified to obtain toner particles having a volume average particle size of about 8 μm. With respect to 100 parts by weight of the toner particles, 0.5 parts by weight of decyltrimethoxysilane-treated silica having an average particle diameter of 12 nm as an external additive, and an average particle diameter of 50 n
1.0 part by weight of silica treated with hexamethyldisilazane of m was added and mixed for 10 minutes with a 5 liter Henschel mixer (manufactured by Mitsui Miike Koki Co., Ltd.) to obtain a toner.

[Comparative Example 4] The same composition and manufacturing conditions as in Example 4, except that the melt-kneading machine in Example 4 was a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd .: TEM50, screw rotating in the same direction). To prepare a toner. At this time, the barrel setting temperature was 130 ° C and the kneading temperature was 135 ° C.

Comparative Example 5 A toner was prepared under the same manufacturing conditions as in Example 4, except that the colorant to be added in Example 4 was changed to 3 parts by weight of a dry pigment of Sian (Blue 15: 3).

(Preparation of Developer) 0.7 parts by weight of a silicone resin was coated on 100 parts by weight of a ferrite core having an average particle diameter of 45 μm with a kneader to prepare a coated carrier, and the above-mentioned Example 1 was used. 3 to 8 and 8 parts by weight of the toners obtained in Comparative Examples 1 to 3 were mixed with 92 parts by weight of the above coated carrier by a V-type blender, and
3 and Comparative Examples 1 to 3 were obtained.

Further, with respect to 100 parts by weight of a ferrite core having an average particle size of 60 μm, 0.005 part by weight of vinylidene fluoride and 0.1 part by weight of a copolymer (70:30) of methyl methacrylate and trifluoroethylene resin are added. Parts were prepared using a kneader device, and 93 parts by weight of the above-mentioned coated carrier was mixed with 7 parts by weight of the toners obtained in Example 4 and Comparative Examples 4 to 5 in a V-type blender, and Example 4 And the developers of Comparative Examples 4 to 5 were obtained.

(Measurement of Colorant Dispersion) The slab after kneading the toner was cut to a thickness of 0.2 μm with a microtome cutter, a photograph of 5000 times was taken with a transmission electron microscope, and 20 cm × 40 cm (40 μm) with an image analyzer. The area% of the aggregate of the colorant in the (× 80 μm visual field) was measured, and the results are shown in Table 1. Here, only aggregates having a particle size of 0.05 μm or more were counted. The area% becomes small in the case where the aggregation is small and the dispersion is advanced to the vicinity of the primary dispersion.

(Measurement of Release Agent Dispersion Diameter) The slab after the toner kneading is cut into a thickness of 0.2 μm with a microtome cutter, a photograph of 5000 times is taken with a transmission electron microscope, and 20 cm × with an image analyzer. 40 cm (40 μm x 80 μm
The field of view) of the release agent was measured for dispersion diameter (equivalent circle diameter calculated from the area). Here, as the release agent, only those having a particle size of 0.1 μm or more were counted, and the results are shown in Table 1.
The equivalent circle diameter is smaller when the dispersion is better.

(Measurement of Charge Amount and Charge Distribution of Developer) The charge amount and the charge distribution of the developer before use and the developer after 10,000 sheets running evaluation with A-Color 635M / C were measured by a charge spectrograph (Xerox). Co.). The charge distribution is very narrow when the ratio (B / A) of the central value (A) of the charge distribution and the width (B) of the charge distribution is less than 0.7, and is 0.7 or more and 1.0 or less. It was judged that it was sometimes narrow, and when it was more than 1.0 and less than 2, it was wide and when it was 2 or more, it was quite wide.

(Measurement of OHP Transmittance) The OHP transmittance is a ratio (%) of light transmitted by irradiating an image fixed on an OHP sheet with light having a frequency suitable for the color. is there. The better the dispersion of the colorant is, the higher the proportion of light that is transmitted, and the higher the proportion of the light that is transmitted, the better the OHP suitability is, the brighter the fixed image is, and the better the coloring of the colorant is. The measurement results are shown in Table 1.

(Evaluation of Image Maintainability and Surface of Photoreceptor) The above developer was used as A-Color 635M manufactured by Fuji Xerox Co., Ltd.
Image quality test of 100,000 sheets under the environment of 20 ° C. and 40% RH. In the image quality test, image density and background fog were evaluated. The image density used was Macbeth density. In the table, 1.0GS indicates that the original document whose density is 1.0 was used.

The evaluation criteria for the fog in the background area are as follows: ⊚ has no fog, ○ has almost no fog, Δ has some fog, × has fog, and XX shows that fog is in a considerably severe state. Show. The criteria for the in-machine stain was determined by observing around the developing device after copying 10,000 sheets. There is no ◎,
◯ indicates almost no, Δ indicates some, but no problem, and X indicates severe stain. The surface of the photoconductor was evaluated by observing the surface of the photosensitive material after copying 10,000 sheets, and was evaluated by the criteria of ⊚ being very good, ◯ being good, and X being bad. The results are shown in Table 1.

[0071]

[Table 1]

[0072]

Industrial Applicability According to the present invention, a self-heating type melt-kneading machine of raw materials of plural shafts with different rotation of screws and chamber cooling is used as a kneading machine, and a wet cake-like water-containing paste coloring material is used as a coloring agent. As a result, it was possible to disperse the colorant particles uniformly and finely in the vicinity of the primary particles in the melt-kneading step. In addition, by adding a specific higher alcohol, and by adjusting the volume average diameter of the higher alcohol to 4 to 20 μm, the above-mentioned dispersion is almost 1
It was possible to reach the next particle size.

Further, by using the above-mentioned higher alcohol, it is possible to prevent adverse effects on the chargeability and color characteristics of the toner, and as a result, the toner of the present invention has a sharp charge distribution and is excellent. Shows charging characteristics, transparency,
It is possible to obtain high image quality with excellent tinting strength, saturation, and color reproducibility. Also, it is possible to obtain background fog, stains inside the machine, and continuously obtain images with stable density. It was possible to provide a toner and a developer that do not damage the toner.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the entire kneading machine used in Example 1.

FIG. 2 is a sectional view of FIG.

FIG. 3 is an explanatory view of a tip clearance portion of the kneading portion of FIG.

4 is an explanatory view of a ridge portion and an abdominal portion of a blade of the kneading screw of FIG.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location G03G 9/087 G03G 9/08 381

Claims (4)

[Claims] 1. A method for producing an electrophotographic color toner containing at least a binder resin and a colorant, wherein a wet cake-like water-containing paste colorant is used as the colorant, and a plurality of kneadings rotating in different directions are used. A method for producing a color toner for electrophotography, which comprises melt-kneading a toner raw material with a melt-kneader equipped with a screw and having a means for cooling an inner wall of a chamber and / or a kneading screw. 2. The method for producing a color toner for electrophotography according to claim 1, wherein a higher alcohol represented by the following general formula is added as a dispersion aid for the colorant, and the mixture is melt-kneaded. _{Formula: CH 3 (CH 2) X} CH 2 OH (X 28
~ 48 integer) 3. The volume average diameter of the higher alcohol is 4 to 2
The method for producing a color toner for electrophotography according to claim 2, wherein the color toner is used in a range of 0 μm. 4. A color toner for electrophotography, which is produced by the production method according to claim 1.