JP2000214635A - Electrostatic charge image developing toner and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner free from staining, the deterioration of image density, the generation of void due to transfer defect and transfer dust and stable in image reproducibility and the producing method. SOLUTION: The producing method includes a process for mixing an additive with a dry toner particle obtained by pulverizing a mixture consisting at least of a binder resin and a coloring agent and having 5-10 μm weight average particle diameter by a mixing device having stirring blades 3, 4 and has a process for stirring only the toner before mixing with the additive under the condition that n2×d×t×h is 5×103-25×104 when the number of revolution of mixer is expressed by (n) (1/sec), the diameter of blade is expressed by (d) (m), mixing time is expressed by (t) (sec) and the number of pieces of the blades is expressed by (h).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like, and a sparse manufacturing method.

[0002]

2. Description of the Related Art In a system for developing an electrostatic image, a fine powder developer called a toner in which a polarity control agent and a colorant are dispersed and contained in a natural or synthetic resin such as a cascade method or a magnetic brush method is used. There is an electrostatic development method. In recent years, with the development of digital copiers and laser printers, there has been a great demand for higher definition images, so-called higher image quality. In particular, like printers, from 300 dpi to 480 dpi and 600 dpi
High image quality such as i becomes mainstream. For this reason, it is possible to reduce the particle size of the toner.

However, when the diameter of the toner is reduced, aggregation and adhesion of the toner particles are liable to occur, and when the electrostatic image is developed, the toner in the replenishing portion is hardly replenished to the developing portion, and the phenomenon that the image density is reduced, that is, so-called replenishment failure. In addition, a phenomenon in which the image density is difficult to be developed from the developing unit to the photoconductor, that is, a phenomenon that the image density is low, and a phenomenon that the image density is difficult to be transferred from the photoconductor and the image density is low, that is, the so-called poor transfer easily occur. These are all caused by an increase in the cohesiveness and adhesion of the toner particles due to the reduction in the particle size of the toner. When the particle size is reduced, the specific surface area of the toner increases, the cohesiveness and the adhesiveness deteriorate, and the fluidity decreases. If the cohesiveness is high, the toner is unevenly distributed at the time of development and charging with the carrier, and the frictional charging between the toner and the carrier is not sufficiently generated, so that the rise in a short time is poor, and the variation of the charging and the reduction of the charging amount are reduced. It will happen.

[0004] When such a variation in charge and a decrease in charge amount occur, toner particles having a low charge amount are easily developed on a non-image portion, resulting in generation of background stain. Further, it is difficult to develop on the image portion, and the image density is reduced. If the fluidity is poor, poor toner replenishment occurs, the amount of development to the developing unit decreases, and the image density decreases. Fluidity is also relevant in transfer, and particularly in a full-color image forming an overlaid image, worm-like image omissions and dust-like stains around characters and images occur. In addition, poor adhesion results in strong adhesion between the toner and the photoreceptor part, resulting in a large residual amount of the photoreceptor part and a small transfer amount on transfer paper during transfer, resulting in poor image density and image density. White spots occur in the image. Such deterioration of the cohesiveness, adhesion and fluidity becomes more remarkable as the toner has a smaller particle size.

[0005] In order to solve these problems, a method of attaching an additive to the toner surface is generally known. In general, an additive is added to the toner particles obtained by pulverization, but is disclosed in JP-A-56-92545 and JP-A-58-92545.
It has been general that toner particles and additives are simultaneously charged into a mixer and mixed as in JP-60754A.
In this method, it is difficult to uniformly mix the additive on the surface of particles having a small particle size, a strong agglomeration, or a low softening and high tackiness particle, and it is insufficient to improve the above-mentioned disadvantages. On the other hand, in order to obtain higher fluidity, a method of increasing the amount of the additive has been proposed.
No. 6229, for example. However, even in this method, there is a limit to the improvement of the fluidity, and there are problems such as the generation of suspended matter which does not adhere to the surface of the toner particles and contamination of the photoreceptor. Further, in order to avoid this problem, methods such as strengthening the mixing and lengthening the mixing time have been adopted. However, there have been problems such as aggregation due to heat generation and burying of the additive on the toner surface.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances of the prior art, and is capable of appropriately mixing additives to prevent background contamination, image density reduction, and transfer failure. An object of the present invention is to provide a toner which is free from white spots and transfer dust and has stable image reproducibility, and a method for producing the same.

[0007]

According to the present invention, the above object is achieved by crushing a kneaded product comprising at least a binder resin and a colorant, and having a weight average particle size of 5 to 10 μm.
In the step of mixing the additive with the mixing device having stirring blades to the dry toner particles of m, it was found that the mixing state of the additive was improved by stirring only the toner before mixing the additive. Stirring before mixing the agents is as follows: When the number of rotations of the mixer is n (1 / second), the blade diameter is d (m), the mixing time is t (second), and the number of blades is h (sheets), n ＾ 2 × d ×
t × h is 5 × 10 ＾ 3 to 25 × 10 ＾ 4, preferably 15
It was found that the improvement was achieved by performing the heat treatment at × 10 ＾ 3 to 18 × 10 ＾ 4. By adjusting to the above range, the toner particles before mixing the additives are appropriately melted and the additives are easily mixed uniformly. If the numerical value is small, the effect is weak, and if it is too large, the aggregation is conversely increased due to heat or the like. It has also been found that mixing the additives within 5 minutes after stirring with the toner alone is more effective. If the additives are not mixed promptly, reaggregation will be caused, and no effect will be obtained.

[0008] Further, the toner aggregation degree before mixing the additives is 55%.
The following is preferred. The degree of aggregation is widely used as a property indicating the fluidity of the toner. The degree of agglomeration was determined as follows. First, a 75μm mesh sieve from the top, 45μ
m mesh sieve and 22 μm mesh sieve were stacked,
g into the top sieve. This is vibrated for 30 seconds with a Hosokawa Micron powder tester. The remaining amount of toner in the sieve is measured, and the degree of aggregation is calculated by the following equation.

[0009]

## EQU1 ## Aggregation degree (%) = ｛(remaining amount of toner in sieve of 75 μm mesh) + 0.6 × (remaining amount of toner in sieve of 45 μm mesh) + 0.2 × (remaining amount of toner in mesh of 22 μm) Remaining amount)｝ / 2.0 × 100

The degree of agglomeration can be adjusted according to the particle shape, particle size distribution, and type and amount of additives. Regarding the particle size distribution, if the average particle size is too small, the amount of the external additive necessary for securing the fluidity increases, which is not suitable. Conversely, if the average particle size is large, there are adverse effects such as insufficient resolution of details. Also, in general,
For the same toner particles, increasing the amount of the additive tends to decrease the degree of aggregation, and decreasing the amount of the additive tends to increase the degree of aggregation.

Further, according to the present invention, the cohesion after mixing the additives is improved by setting the cohesion to 5 to 20%. In addition, it was found that the above treatment before mixing the additives was effective even with the same degree of aggregation. Further, although the reason is not clear, it has been found that the use of hydrophobic silica and titanium oxide in combination increases the degree of fusion of transfer dust, particularly in a full-color system for forming a superimposed image.

[0012] Examples of hydrophobic silica fine particles include HD.
KH2000, HDK H2000 / 4, HDK
H 2050EP, HVK21 (or Hoechst) or R
972, R974, RX200, RY200, R20
2, R805, R812 (Nippon Aerosil), TS
720 (Cabot).

The fine particles of titanium oxide include P-2.
5 (Nippon Aerosil), STT-30, STT-65C
-S (above titanium industry), TAF-140 (Fuji titanium industry), MT-150W, MT-500B, MT-60
0B (or more). In particular, as the titanium oxide fine particles subjected to the hydrophobic treatment, an anatase-type or rutile-type crystalline or non-crystalline one can be used.
-805 (Nippon Aerosil) or MT-1 as rutile type
00S, MT-100T, MT-150A, MT150
AFM (above Takeka), STT-30A, STT-6
2S-S, (above titanium industry), MT-100S, MT
-100T (taker), IT-S (Ishihara Sangyo) and the like.

In order to obtain hydrophobized silica fine particles, titania fine particles and alumina fine particles, hydrophilic fine particles are treated with a silane coupling agent such as methyltrimethoxysilane, methyltriethoxysilane or octyltrimethoxysilane. Can be obtained. Further, it can be obtained by a polysiloxane treatment.

The amount of the silica fine particles hydrophobicized with respect to the toner is suitably 0.1 to 1.2 parts by weight, and more preferably 0.1 to 1.2 parts by weight.
2 to 0.8 parts by weight. If the amount of silica particles is large, defects such as transfer dust appear, and if the amount is small, the degree of aggregation increases,
It was observed that there were many omissions during transfer. Titanium oxide may be added in the same manner, and the amount of the titanium fine particles is suitably 0.1 to 1.2 parts by weight, more preferably 0.3 to 1.2 parts by weight, based on the toner.
To 1.0 part by weight.

By simultaneously adding silica and titanium,
Defects such as transfer dust can be suppressed, and the amount of added silica increases the margin. If the amount of titanium is too large, omission during transfer tends to occur. The mixing ratio of silica and titanium is 1/9 to 6/4, preferably 2/8 to 5/5, and more preferably 3/7 to 5/5. As other additives, for example, fatty acid metal salts (such as zinc stearate and aluminum stearate), other metal oxides (such as aluminum oxide, tin oxide and antimony oxide), and fluoropolymers may be contained.

The present invention can be applied to both monochrome and color toners, and can also be applied to one-component and two-component development systems. As the toner material used in the present invention, all known materials can be used. As the binder resin, polystyrene, poly p-chlorostyrene,
Styrene such as polyvinyltoluene and its substituted polymers; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid Methyl copolymer, styrene ethyl acrylate copolymer, styrene-butyl acrylate copolymer,
Styrene octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer,
Styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Styrene-based copolymers such as styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester,
Epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. Is mentioned. Examples of incompatible combinations include styrene-butyl acrylate copolymer and resins having greatly different properties such as polyester, epoxy resin, and epoxy polyol resin. Significantly different combinations of groups can also be obtained.

As the colorant, all known dyes and pigments can be used, for example, carbon black, nigrosine dye,
Iron black, Naphthol yellow S, Hansa yellow (10
G, 5G, G), cadmium yellow, yellow iron oxide,
Loess, graphite, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G) , R), tartrazine lake, quinoline yellow lake, anthrazan yellow BGL, isoindolinone yellow, red bengara, lead red, lead red, cadmium red, cadmium mercury red, antimony red, permanent red 4R, para red, Phisay Red, Parachlor Orthonitroaniline Red, Risor Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine Min BS, Permanent Red (F2R, F4R, FRL, FRLL, F4R
H), Fast Scarlet VD, Belcan Fast Rubin B, Brilliant Scarlet G, Lisor Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5
B, Toluidine Maroon, Permanent Bordeaux F2
K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Museum, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thio Indigo Maroon,
Oil red, quinacridone red, pyrazolone red, polyazo red, chrome vermillion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkali blue lake, peacock blue lake, victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue , Fast Sky Blue, Indanthrene Blue (R
S, BC), indigo, ultramarine, navy blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt violet, manganese violet, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalocyanine Green, Anthraquinone Green, Titanium Oxide, Zinc White, Lithobon and mixtures thereof can be used. The amount used is generally 0.1 to 50 parts by weight based on 100 parts by weight of the binder resin.

The toner of the present invention may contain a charge control agent, if necessary. As the charge control agent, any known charge control agents can be used. For example, nigrosine pigments, triphenylmethane pigments, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine pigments, alkoxy amines, quaternary ammonium salts (fluorine-modified) Quaternary ammonium salts), alkyl amides, phosphorus alone or compounds, tungsten alone or compounds, fluorine-based activators, salicylic acid metal salts, and salicylic acid derivative metal salts.

In the present invention, the amount of the charge control agent used is determined by the type of binder resin, the presence or absence of additives used as required, and the toner production method including the dispersion method, and is uniquely limited. However, preferably, 0.1 to 100 parts by weight of the binder resin
Used in the range of 10 parts by weight. More preferably, 2-
The range of 5 parts by weight is good, but if it is less than 0.1 part by weight, the negative charge of the toner is insufficient, which is not practical. If the amount is more than 10 parts by weight, the chargeability of the toner is too large, and the electrostatic attraction between the toner and the carrier or the charging member is increased, so that the fluidity of the developer is reduced and the image density is reduced.

1 and 2 show specific examples of a mixer having a stirring blade used in the present invention. It has the configuration shown in the cross-sectional view of FIG. 1, and the toner and the carbonizing agent are put in the mixing tank (2), and the stirring blades (3) and (4) are rotated to mix. The mixture is discharged from the outlet (5).

[0022]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. All parts are parts by weight.

[Production Example] (Production Example 1) Polyester resin 100 parts Acid value 3 Hydroxyl value 25 Mn 45000 Mw / Mn 4.0 Tg 60 ° C Carbon black 10 parts Polypropylene 5 parts Quaternary ammonium salt 2 parts , And then melt-kneaded with a two-roll mill, and the kneaded material was rolled and cooled. Thereafter, the treatment was performed by changing the pulverization conditions, and after classification, the particles A and B having the degree of aggregation shown in Table 1 were obtained.
I got

(Production Example 2) 1200 parts of black toner water 200 parts of phthalocyanine green water-containing cake (solid content: 30%) 540 parts of carbon black (MA60 manufactured by Mitsubishi Chemical Corporation) are thoroughly stirred with a flasher. Here, a polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000,
(Mw / Mn: 4.0, Tg; 60 ° C.) 1200 parts were added and kneaded at 150 ° C. for 30 minutes, then 1000 parts of xylene was added and kneaded for 1 hour. After removing water and xylene, rolling, cooling, pulverizing with a pulperizer, and mastering were performed. A batch pigment was obtained. Polyester resin 100 parts Acid value 3 Hydroxyl value 25 Mn 45000 Mw / Mn 4.0 Tg 60 ° C Master batch 8 parts Zinc salicylate derivative (Bontron E84, Orient Chemical) 2 parts Mix the above materials with a mixer and melt with a two-roll mill The kneaded product was rolled and cooled. Here, the maximum diameter of the pigment was 0.4 μm. Thereafter, the particles were pulverized and classified to obtain particles C having a weight average particle diameter of 7.5 μm.

(Production Example 3) 600 parts of yellow toner water, 1200 parts of Pigment Yellow 17 water-containing cake (solid content: 50%) are thoroughly stirred with a flasher. Here, a polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000,
Mw / Mn; 4.0, Tg; 60 ° C.)
After kneading at 150 ° C. for 30 minutes, 1000 parts of xylene was added and kneading was further performed for 1 hour. After removing water and xylene, the mixture was rolled and cooled, pulverized with a pulperizer, and further passed through a three-roll mill for two passes to obtain a master batch pigment. Polyester resin 100 parts Acid value 3 Hydroxyl value 25 Mn 45000 Mw / Mn 4.0 Tg 60 ° C Master batch 8 parts Zinc salicylate derivative (Bontron E84, Orient Chemical) 2 parts Mix the above materials with a mixer and melt with a two-roll mill The kneaded product was rolled and cooled. Here, the maximum diameter of the pigment was 0.4 μm. Thereafter, the particles were pulverized and classified to obtain particles D having a weight average particle diameter of 7.5 μm.

(Production Example 4) 600 parts of magenta toner water and 1200 parts of Pigment Red 57 water-containing cake (solid content: 50%) are thoroughly stirred with a flasher. Here, a polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000,
Mw / Mn; 4.0, Tg; 60 ° C.)
After kneading at 150 ° C. for 30 minutes, 1000 parts of xylene was added and kneading was further performed for 1 hour. After removing water and xylene, the mixture was rolled and cooled, pulverized with a pulperizer, and further passed through a three-roll mill for two passes to obtain a master batch pigment. Polyester resin 100 parts Acid value 3 Hydroxyl value 25 Mn 45000 Mw / Mn 4.0 Tg 60 ° C Master batch 8 parts Zinc salicylate derivative (Bontron E84, Orient Chemical) 2 parts Mix the above materials with a mixer and melt with a two-roll mill The kneaded product was rolled and cooled. Here, the maximum diameter of the pigment was 0.4 μm. Thereafter, the particles were pulverized and classified to obtain particles E having a weight average particle diameter of 7.5 μm.

(Production Example 5) 600 parts of cyan toner water, 1200 parts of Pigment Blue 15: 3 water-containing cake (solid content: 50%) are thoroughly stirred with a flasher. Here, a polyester resin (acid value; 3, hydroxyl value; 25, Mn; 45000,
Mw / Mn; 4.0, Tg; 60 ° C.)
After kneading at 150 ° C. for 30 minutes, 1000 parts of xylene was added and kneading was further performed for 1 hour. After removing water and xylene, the mixture was rolled and cooled, pulverized with a pulperizer, and further passed through a three-roll mill for two passes to obtain a master batch pigment. Polyester resin 100 parts Acid value 3 Hydroxyl value 25 Mn 45000 Mw / Mn 4.0 Tg 60 ° C Master batch 5 parts Zinc salicylate derivative (Bontron E84, Orient Chemical) 2 parts Mix the above materials with a mixer and melt with a two-roll mill The kneaded product was rolled and cooled. Here, the maximum diameter of the pigment was 0.4 μm. Thereafter, the particles were pulverized and classified to obtain particles F having a weight average particle size of 7.5 μm.

Example 1 The particles A obtained in Production Example 1 were charged into a Henschel mixer (FM-20B manufactured by Mitsui Mining Co., Ltd.), and stirred for 300 seconds before the external additives were charged. At this time, the rotational speed of the mixer n = 30 (1 / sec), the blade diameter d = 0.265 (m), the number of blades h = 2 (sheets), and n ＾ 2 × d × t × h = 14.1. 3 × 10 ＾ 4.
After this pretreatment, 0.8 wt% of hydrophobic silica (R972 Nippon Aerosil) was added and mixed for 180 seconds to obtain a toner. At this time, the time from the end of the pre-stirring to the start of the additive mixing was 3 minutes. The obtained toner is used to form an image on an experimental machine having a one-component developing device, and the image after printing out 5000 images is limited in comparison with a sample. Evaluations of density reduction and transfer dust were performed to confirm image reproducibility. Table 2 shows the evaluation results.

(Example 2) The stirring before mixing the external additives was 30 seconds, the number of revolutions of the mixer n = 20 (1 / sec), the blade diameter d
= 0.265 (m), the number of blades h = 2 (sheets), and n ＾ 2
Processing was performed in the same manner as in Example 1 except that xd × t × h = 6.4 × 10 ＾ 3. Table 2 shows the evaluation results.

Example 3 The stirring before mixing the external additives was 510
And the number of rotations of the mixer n = 300 (1 / second), the blade diameter d = 0.265 (m), the number of blades h = 2 (sheets), and n ＾
Processing was performed in the same manner as in Example 1 except that 2 × d × t × h = 24.3 × 10 ＾ 4. Table 2 shows the evaluation results.

Example 4 A process was performed in the same manner as in Example 1 except that the time from the end of the pretreatment to the start of the mixing of the additives was changed to 8 minutes. Table 2 shows the evaluation results.

Example 5 The same treatment as in Example 1 was performed using the particles B. Table 2 shows the evaluation results.

Example 6 The color toners obtained in Production Examples 2 to 5 were processed in the same manner as in Example 1.
An image was formed using the full color toner obtained with a full-color experimental machine, and the evaluation was made on the hollowness of the image, thickening of characters, background fouling, and transfer dust compared to the limit sample. Table 2 shows the evaluation results.

(Example 7) Instead of the hydrophobic silica of Example 3, titanium oxide (MT-150A, Takeka) was added in an amount of 1.0%.
% By weight to obtain toners of respective colors. Evaluation was performed in the same manner as in Example 6. Table 2 shows the evaluation results.

Example 8 Each color toner was prepared by using 0.6% by weight of hydrophobic silica (H2000, Hoechst) and 0.9% by weight of titanium oxide (MT-150A, Takeka) as additives in Example 1. Evaluation was performed in the same manner as in Example 6.
Table 2 shows the evaluation results.

Comparative Example 1 Particles B obtained in Production Example 1 were charged into a Henschel mixer, and stirred for 30 seconds before the external additives were charged. At this time, the mixer rotation speed n = 15 (1
/ Sec), blade diameter d = 0.265 (m), number of blades h =
2 (sheets), and n {2 × d × t × h = 3.6 × 10}.
It becomes 3. After this pretreatment, 0.8 wt% of hydrophobic silica (R972, Nippon Aerosil) was added and mixed for 180 seconds to obtain a toner. The obtained toner is used to form an image on an experimental machine having a one-component developing device, and the image after outputting 5000 images is limited in comparison with a sample. Evaluations of density reduction and transfer dust were performed to confirm image reproducibility. Table 2 shows the evaluation results.

(Comparative Example 2) The particles A obtained in Production Example 1 were charged into a Henschel mixer, and stirred for 60 seconds before the external additives were charged. At this time, the mixer rotation speed n = 30 (1
/ Sec), blade diameter d = 0.265 (m), number of blades h =
2 (sheets), and n ＾ 2 × d × t × h = 28.6 × 10
$ 4. After this pretreatment, hydrophobic silica (R972,
0.8 wt% of Nippon Aerosil) was added and mixed for 180 seconds to obtain a toner. The obtained toner is used to form an image on an experimental machine having a one-component developing device, and the image after outputting 5000 images is limited in comparison with a sample. Evaluation of density reduction and transfer dust was performed to confirm image reproducibility. Table 2 shows the evaluation results.

(Comparative Example 3) Hydrophobic silica (R972, Nippon Aerosil) was added to the particles A obtained in Production Example 1 for 0.8 w.
t% was added and mixed for 180 seconds to obtain a toner. An image is formed on the obtained toner with an experimental machine having a one-component developing device,
Compared to the limit sample, after 5,000 images have been output, white spots, character thickening and background smear due to image transfer failure,
Evaluations of density reduction and transfer dust were performed to confirm image reproducibility. Table 2 shows the evaluation results.

[0039]

[Table 1]

[0040]

[Table 2] Here, the cohesion degree shows the maximum value and the minimum value in the example of using the toner of four colors. In addition, the rank evaluation was 5; best; 3; classified into 5 levels with a practically acceptable level as a guide, and visually judged. The particle size distribution was 5 to 10 μm in all cases.
In the range.

[0041]

As has been apparent from the detailed and specific description, the present invention makes it possible to mix additives properly and eliminate background smear, image density reduction, white spots due to poor transfer, and transfer dust. This is an extremely excellent effect that a toner having stable image reproducibility can be provided.

[Brief description of the drawings]

FIG. 1 is a side view of a mixer having a stirring blade suitable for carrying out the present invention.

FIG. 2 is a view of a mixer having a stirring blade suitable for carrying out the present invention as viewed from directly above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mixing tank 2 Inside mixing tank 3 Stirrer blade 1 4 Stirrer blade 2 5 Discharge port

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ken Mochizuki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hideo Ichikawa 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor Kanjiro Kawasaki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Yoichi Maekawa 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Tomomi Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H005 AA08 AB04 AB10 CA26 CB07 CB13 EA05 EA07 EA10

Claims (7)

[Claims] 1. A weight average particle system 5 obtained by pulverizing a kneaded product comprising at least a binder resin and a colorant.
A step of mixing the additive with the mixing device having stirring blades to the dry toner particles having a particle diameter of 10 μm to 10 μm.
Blade diameter d (m), mixing time t (second), number of blades h
A method for producing a toner, wherein n ＾ 2 × d × t × h is 5 × 10 × 3 to 25 × 10 ＾ 4. 2. Mixing of additives is performed only after stirring with toner alone.
2. The method according to claim 1, wherein the step is performed within minutes. 3. The toner for developing an electrostatic charge image obtained by the method according to claim 1, wherein the degree of aggregation of the toner before mixing the additives is 55% or less. 4. An electrostatic image developing toner obtained by the method according to claim 1, wherein the toner has an aggregation degree of 5 to 20% or less. 5. The method according to claim 3, wherein the additive to be mixed is hydrophobic silica fine particles, and the additive is contained in an amount of 0.1 to 1.0 part based on 100 parts of the toner. Charge image developing toner. 6. The electrostatic image development according to claim 3, wherein the additive to be mixed is fine particles of titanium oxide, and is contained in an amount of 0.1 to 1.2 parts based on 100 parts of the toner. For toner. 7. The method according to claim 3, wherein the silica / titanium ratio of the additive to be mixed is 1/9 to 6/4.
3. The toner for developing an electrostatic image according to item 1.