JP2002229267A - Method for manufacturing electrostatic charge image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an electrostatic charge image developing toner by using toner mother particles of a small particle size which have high triboelectric property and good fluidity, excellent preserving property and which can form preferable images without causing transfer failure. SOLUTION: The electrostatic charge image developing toner is manufactured by adding and mixing silica-based inorganic fine particles (A) having 10 to 50 nm number average particle size and titania inorganic fine particles (B) having 10 to 90 nm number average particle size as the external additive component to toner mother particles composed of at least a coloring agent and a binder resin and having <=10 μm average particle size. In the method for manufacturing the electrostatic charge image developing toner, mixing of the toner mother particles and the inorganic fine particles is repeatedly carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a toner for developing an electrostatic image.

[0002]

2. Description of the Related Art Conventionally, electrophotography has been disclosed in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910.
(U.S. Pat. No. 3,666,363) and Japanese Patent Publication No. 43-24748 (U.S. Pat.
No. 1,361), an electric latent image is generally formed on an electrostatic image carrier by various means, and then the electric latent image is formed with toner. After developing, the toner image is transferred to a transfer material such as paper, if necessary. Then, the toner image is fixed to the transfer material by heating, pressurizing, solvent vapor, or the like. This is a method in which the toner remaining on the charge image carrier is cleaned, an electric latent image is formed again on the electrostatic image carrier, and this process is repeated to obtain a large number of copy images.

There are various known developing methods for developing an electric latent image with toner to form a toner image. However, the developing method is roughly classified into a dry developing method and a wet developing method. The method is divided into a method using a developer and a method using a one-component developer. The two-component developer is mainly composed of a mixture of a toner in which a colorant such as carbon black is dispersed and contained in a binder resin and a carrier such as iron powder or glass beads. As a developing method using, a magnetic brush method using an iron powder carrier and a cascade method using a glass bead carrier are known. The one-component developer is composed of only a toner, and there are a magnetic one-component developer containing a magnetic material in the toner and a non-magnetic one-component developer not containing a magnetic material. Are known, such as a powder cloud method, a magnedry method, and an impression method.

[0004] In order to improve characteristics such as fluidity, transferability, developability and storability required for these developers, additives are externally added to toners.

Japanese Patent Publication No. 63-33698 discloses that by optimizing the "mixing degree" of a toner and an external additive,
There has been disclosed a method for producing a developer for the purpose of effectively utilizing various physical properties of a toner.

[0006] Japanese Patent Application Laid-Open No. Hei 10-232508 discloses that charging is performed by setting a mixing time when an additive is added to toner base particles between a secondary singular point of chargeability and a singular point of storage property. It has been proposed to obtain a toner exhibiting good characteristics in both properties and storage stability. However, the characteristic value of the charging property and the characteristic value of the storage property do not always have a singular point. In addition, when continuous mixing is performed, the rate of change in the adhesion between the toner base particles and the additives in the powder in the mixer is slow, and the mixing time is prolonged to obtain the optimum fluidity, thereby increasing the productivity. There is a problem that leads to a decline. Further, continuous mixing for a long period of time also exerts a stress on the toner particles, and the toner particles are pulverized to generate fine powder, which is one of the causes that hinders the uniformity of image quality.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems in the prior art. Accordingly, an object of the present invention is to provide a toner base particle having a small particle diameter, which has high triboelectric charging property, good fluidity, excellent storage stability, and can form a good image without causing transfer failure. It is an object of the present invention to provide a method for producing a used electrostatic image developing toner.

[0008]

As a result of the study, the present inventors have found that silica-based inorganic fine particles having a number average particle size of 10 to 50 nm as an external additive component are added to toner base particles having an average particle size of 10 μm or less. It has been found that, when A) and the titania-based inorganic fine particles (B) having a number average particle size of 10 to 90 nm are mixed and adhered under specific conditions, a favorable charge rising rate, transferability, and agglomeration degree are improved. Thus, the present invention has been completed.

The method for producing a toner for developing an electrostatic charge image of the present invention is characterized in that the toner has an average particle diameter of at least 1 including a colorant and a binder resin.
In mixing the silica-based inorganic fine particles (A) having a number-average particle diameter of 10 to 50 nm and the titania-based inorganic fine particles (B) having a number-average particle diameter of 10 to 90 nm as components of the external additive in the toner base particles having a particle size of 0 μm or less. And repeating the mixing and stirring step. This makes it possible to efficiently and uniformly add the inorganic fine particles by the rising motion of the rotational motion of the mixer stirring blade. In addition, compared to the case where continuous mixing is performed, a toner having a higher charge buildup of the toner and a higher image density when printed can be obtained.

[0010] According to a second aspect of the present invention, there is provided a method for producing an electrophotographic toner according to the first aspect, wherein the stirring rise time of the mixing blade is 3 seconds or more and 15 seconds or less. If the stirring rise time is less than 3 seconds,
The number of revolutions is instantaneously reached and the toner particles are pulverized by the stress to generate fine powder. On the other hand, if the time is 16 seconds or more, the resistance of the powder at the time of rising of the rotation of the stirring blade becomes small, so that the desired mixing energy cannot be obtained, and the adhesion of the added inorganic fine particles becomes weak. Therefore, in order to satisfy the adhesion of the inorganic fine particles while preventing the generation of fine powder, it is necessary to set the stirring rise time of the mixing blade of the mixer to 3 seconds or more and 15 seconds or less.

According to a third aspect of the present invention, there is provided a method for producing an electrophotographic toner, wherein a peripheral speed of a blade tip is not less than 10 m / s and not more than 50 m / s. When the peripheral speed of the blade tip is less than 10 m / s, the mixing energy is low and uniform mixing quality cannot be obtained. When the peripheral speed is more than 50 m / s, frictional heat generated between powders causes fusion and aggregation of toner, resulting in impaired fluidity. Becomes Therefore, the peripheral speed of the blade tip is 10 m / s
It is necessary to be at least 50 m / s.

According to a fourth aspect of the present invention, there is provided a method for producing an electrophotographic toner, wherein the number of mixing cycles is 3 to 10 times. This range is suitable for obtaining a toner having a good charge rise.

According to a fifth aspect of the invention, there is provided a method for producing an electrophotographic toner, wherein each mixing time is 20 seconds or more and 60 seconds or less. If the mixing time is less than 20 seconds, the mixing energy per cycle is low, and it is necessary to increase the number of times of mixing, and the processing time per batch increases. Also, 61
When the time is longer than seconds, the change in the adhesion between the additive and the base toner is poor, so that there is no effect. Therefore, each mixing time needs to be set to 20 seconds or more and 60 seconds or less.

The method for producing an electrophotographic toner according to claim 6, wherein the inorganic fine particles (B) are added and mixed with the inorganic fine particles (A).
Is characterized by adding and mixing. Toner mother particles and silica-based inorganic fine particles (A), titania-based inorganic fine particles (B)
In this case, the silica-based inorganic fine particles have lower adhesion to the base toner. Further, when the stirring cycle is increased, the titania-based fine particles are buried in the base toner, and it is difficult to obtain a charge rising effect. Therefore, by adding and mixing the silica-based inorganic fine particles after the addition and mixing of the silica-based inorganic fine particles, it becomes possible to secure the adhesion of the silica-based inorganic fine particles without burying the titania.

According to a seventh aspect of the present invention, there is provided a method of manufacturing an electrophotographic toner according to the first aspect, wherein the addition amount of the silica-based inorganic fine particles (A) is 1% by weight or less.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment of the method for producing a toner for developing an electrostatic image according to the present invention, as an external additive, silica-based inorganic fine particles (A) having a number average particle size of 10 nm to 50 nm and a number average particle size are used. When mixing with the base toner using 10 to 90 nm of titania-based inorganic fine particles (B), the mixing and stirring step is repeated.

The toner for electrophotography (hereinafter, referred to as toner) according to the present embodiment includes a colorant such as carbon black, a charge controlling agent, and a release agent such as wax on the surface of a binder. The external additive particles are externally added, that is, attached to the surface of the toner particles to which the agent is internally added.

As the silica-based inorganic fine particles, those made hydrophobic are preferable, and specifically, HDKH 2000, HDK
H 2000/4, HDK H 2050EP, HV
K21 (above Hoechst), R972, R974, RX2
00, RY200, R202, R805, R812 (Nippon Aerosil) and TS720 (Cabot).

As titania-based fine particles, P-25 (Nippon Aerosil), STT-30, STT-65C-S (Titanium Industry), TAF-140 (Fuji Titanium Industry),
MT-150W, MT-500B, MT-600B (hereafter, Taker) and the like.

As the titanium oxide fine particles subjected to the hydrophobic treatment, crystalline or non-crystalline ones of anatase type or rutile type can be used, and T-805 (Nippon Aerosil) or MT-type as rutile type can be used. 100S, MT-100
T, MT150A, MT150AFM (above Takei), STT-30A, STT-62S-S (above titanium industry), MT-100S, MT-100T (above 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.

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. When the amount of the silica fine particles was large, defects such as transfer dust appeared, and when the amount was small, it was observed that the degree of agglomeration was increased and the omission during transfer was large.

When the toner particles and the external additives are mixed and dispersed by stirring with a mixer or the like, the external additives that have been secondary aggregated are crushed with stirring and externally added to the surface of the toner particles. At this time, if the mixing and stirring are continuously performed, the powder in the mixer has a large fluidity, so that the friction energy by the mixing blade is hardly added. Also, the internal temperature rises, causing the toner to solidify. On the other hand, when intermittent mixing is performed, a large amount of energy is instantaneously added due to frictional energy between the stirring blade and the toner powder at the start of stirring, so that the additive is more uniformly added.

Next, the toner particles before the treatment with the external additive will be described. The components of the toner particles before the treatment with the external additive used in the production method of the present invention include a binder resin, a colorant, a charge control agent, and a release agent.

Examples of the binder resin include styrene-based copolymers such as polystyrene, styrene, butadiene copolymer and styrene-acryl copolymer, polyethylene, polyethylene-vinyl acetate copolymer and polyethylene-vinyl alcohol copolymer. And ethylene-based copolymers, phenolic resins, epoxy resins, allyl phthalate resins, polyamide resins, polyester resins, and maleic acid resins.

Examples of the coloring agent include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine yellow, methylene blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and lamp. Black, Rosebergal, etc., and also mixtures thereof.

As charge control agents, for example, quaternary ammonium salts, nigrosine, amino compounds, and organic dyes, particularly basic dyes and salts thereof, are known, such as benzyldimethyl-hexadecylammonium chloride, decyl-trimethylammonium. Chloride, nigrosine base, nigrosine hydrochloride, safranin γ, crystal violet and the like can be used. Incidentally, nigrosine base and nigrosine hydrochloride are often used as positive charge control agents.

As the releasing agent, polypropylene,
Polyethylene or paraffin wax can also be used. Note that the binder, the charge control agent, the release agent, and the colorant are not limited to the above-described materials, and other types of materials can be used. These toner components are usually manufactured through the steps of mixing, kneading, pulverizing, and classifying.

An embodiment used in the method for producing a toner according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view of a high-speed stirring type mixer. The high-speed stirrer-type mixer specified in the present invention has a form as shown in FIG. 1 and includes a single stirring rotor or a stirring rotor for applying a shearing force for mixing and stirring the classified toner and the inorganic fine particles. The one provided with a plurality of sheets was used.

In the drawing, reference numeral 1 denotes a mixing tank main body, and a temperature control jacket 6 for circulating hot water for temperature adjustment outside the mixing tank.
Is surrounded. Reference numeral 2 denotes a powder discharge port for discharging a mixture of toner and fine particles mixed in the main body, and reference numerals 3A and 3B denote two-stage upper and lower stirring rotors rotating at a lower portion in the mixing tank, which are constituted by a plurality of sheets. 4 is a laminar flow plate for adjusting the flow of the mixture in the mixing tank, 5 is the lid of the mixing tank, 7 is a temperature-controlled water inlet for injecting temperature-controlled water of the temperature control jacket 6, and 8 is a temperature-controlled water outlet.

Hereinafter, the present invention will be described with reference to examples.
These are only one mode showing the present invention, and the technical content of the present invention is not limited thereto.

The following toners were used before mixing the external additives used in Examples and Comparative Examples. That is, a polyester resin (manufactured by Sanyo Chemical Co., Ltd.),
Weight% and carbon black as colorant (Mitsubishi Chemical)
8% by weight, 3% by weight of a quaternary ammonium salt (manufactured by Orient) as a charge control agent, and 4% by weight of carnauba wax (manufactured by Neos) as a release agent are obtained by a mixing step. The resulting mixture was melted, kneaded and integrated. Thereafter, the kneaded material integrated in the kneading step was pulverized into granules, and the obtained granules were classified to obtain toner granules having an average particle diameter of 9 μm.

Example 1 2 kg of the above toner particles having an average particle diameter of 9 μm were weighed, and a hydrophobic silica (R-9) having a number average particle diameter of 30 nm was measured.
72 Nippon Aerosil) was weighed at 1.5% by weight based on the toner, and titania having a number average particle diameter of 50 nm was weighed at 0.3% by weight based on the toner, and these were weighed with a mixer (product name: Super Mixer). SMV200, Kawata Corporation
Manufactured). Then, this mixer is rotated at a rotation speed of the blade tip peripheral speed of 60 m / s and the rise time is 3 seconds,
11 cycles of mixing for 15 seconds and stopping for 60 seconds were performed to obtain a toner for an electrostatic copying machine.

Example 2 2 kg of the above toner particles having an average particle diameter of 9 μm were weighed, and a hydrophobic silica (R-R) having a number average particle diameter of 30 nm was prepared.
972 manufactured by Nippon Aerosil Co., Ltd.)
The toner was weighed, and 0.3% by weight of titania having a number average particle diameter of 50 nm was weighed with respect to the toner, and these were mixed with a mixer (product name: Super Mixer SMV200, Kawata Corporation).
Manufactured). Then, the mixer was rotated at a blade tip peripheral speed of 60 m / s at a rotation speed of 5 seconds,
11 cycles of mixing for 15 seconds and stopping for 60 seconds were performed to obtain a toner for an electrostatic copying machine.

Example 3 2 kg of the above toner particles having an average particle diameter of 9 μm were weighed, and a hydrophobic silica (R-R) having a number average particle diameter of 30 nm was measured.
972 manufactured by Nippon Aerosil Co., Ltd.)
The toner was weighed, and 0.3% by weight of titania having a number average particle diameter of 50 nm was weighed with respect to the toner, and these were mixed with a mixer (product name: Super Mixer SMV200, Kawata Corporation).
Manufactured). Then, this mixer was rotated at a blade tip peripheral speed of 40 m / s at a rotational speed of 5 seconds,
11 cycles of mixing for 15 seconds and stopping for 60 seconds were performed to obtain a toner for an electrostatic copying machine.

Example 4 2 kg of the above toner particles having an average particle size of 9 μm were weighed, and a hydrophobic silica (R-R) having a number average particle size of 30 nm was prepared.
972 manufactured by Nippon Aerosil Co., Ltd.)
The toner was weighed, and 0.3% by weight of titania having a number average particle diameter of 50 nm was weighed with respect to the toner, and these were mixed with a mixer (product name: Super Mixer SMV200, Kawata Corporation).
Manufactured). Then, this mixer was rotated at a blade tip peripheral speed of 40 m / s at a rotational speed of 5 seconds,
Six cycles of mixing for 15 seconds and stopping for 60 seconds were performed to obtain a toner for an electrostatic copying machine.

Example 5 2 kg of the above toner particles having an average particle diameter of 9 μm were weighed, and a hydrophobic silica (R-R) having a number average particle diameter of 30 nm was prepared.
972 manufactured by Nippon Aerosil Co., Ltd.)
The toner was weighed, and 0.3% by weight of titania having a number average particle diameter of 50 nm was weighed with respect to the toner, and these were mixed with a mixer (product name: Super Mixer SMV200, Kawata Corporation).
Manufactured). Then, this mixer was rotated at a blade tip peripheral speed of 40 m / s at a rotational speed of 5 seconds,
Six cycles of mixing for 30 seconds and stopping for 60 seconds were performed to obtain a toner for an electrostatic copying machine.

Example 6 2 kg of the above toner particles having an average particle diameter of 9 μm were weighed, and a hydrophobic silica (R-R) having a number average particle diameter of 30 nm was obtained.
972 manufactured by Nippon Aerosil Co., Ltd.)
Weight% and mix them with a mixer (product name: Super Mixe
r SMV200, manufactured by Kawata Corporation. Then, the mixer is rotated at a blade tip peripheral speed of 40 m / s at a rotation speed of 5 msec, and a cycle of a rise time of 5 sec, a mixing time of 30 sec and a stop of 60 sec is performed for 3 cycles. 0.3% by weight was weighed and charged. Then, the mixer was rotated at a blade tip peripheral speed of 40 m / s at a rotation speed of 5 seconds,
Six cycles of mixing for 30 seconds and stopping for 60 seconds were performed to obtain a toner for an electrostatic copying machine.

Example 7 2 kg of the above toner particles having an average particle diameter of 9 μm were weighed, and a hydrophobic silica (R-9) having a number average particle diameter of 30 nm was measured.
72, manufactured by Nippon Aerosil Co., Ltd., and weighed at 0.8% by weight based on the toner.
SMV200, manufactured by Kawata Corporation). And
This mixer is rotated at a blade tip peripheral speed of 40 m / s, and a cycle of a rise time of 5 seconds, a mixing time of 30 seconds and a stop of 60 seconds is performed for 3 cycles.
0.3 nm by weight of the titania of 0 nm with respect to the toner was measured and introduced. Then, the mixer was rotated at a blade tip peripheral speed of 40 m / s at a rotational rising time of 5 seconds, 30 minutes.
Six cycles of mixing for 60 seconds and stopping for 60 seconds were performed to obtain a toner for an electrostatic copying machine.

Comparative Example A toner for electrostatic copying was obtained in the same manner as in Example 1 except that the mixing was not performed repeatedly but in the usual manner.

Using the electrophotographic toners obtained in these Examples and Comparative Examples, a copier IMAG manufactured by Ricoh Co., Ltd. was used.
Image evaluation and durability evaluation were performed using IOMF6550. Table 1 shows the results. The measurement of the degree of aggregation in these examples and comparative examples was performed using a powder tester. That is, 2.0 g of the toner is used for opening 150 μm.
The residual toner amount on each of the sieves after passing through sieves of m, 75 μm, and 45 μm was measured, and was calculated using the following equation. Aggregation degree (%) = (A + 0.6 × B + 0.2 × C) / 2.
0 × 100 A: Remaining amount of toner on sieve with mesh of 150 μm (g) B: Remaining amount of toner on sieve with mesh of 75 μm (g) C: Remaining toner on sieve with mesh of 45 μm (g)

As for the transferability, a solid black image was copied, and the resulting copy was measured for white spots. The image density was measured with a Macbeth densitometer.

[0043]

[Table 1]

[0044]

As is apparent from the above description, the toner obtained by the novel external addition step according to the method for producing a toner for an electrostatic copying machine of the present invention has high triboelectric charging property and good fluidity. In addition, excellent effects such as high image density by continuous printing and good transferability can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a high-speed stirring type mixer used in a toner manufacturing method according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mixing tank main body 2 Powder discharge port 3A, 3B stirring rotor 4 Laminar flow plate 5 Lid 6 Temperature control jacket 7 Regulated water inlet 8 Regulated water outlet

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masahiro Kawamoto 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 2H005 AA08 AB10 CB07 CB13 EA05 EA07

Claims (7)

[Claims] 1. A method according to claim 1, wherein the toner base particles having an average particle diameter of at most 10 μm comprising a colorant and a binder resin have silica-based inorganic fine particles (A) having a number average particle diameter of 10 to 50 nm as a component of an external additive. A method for producing a toner for developing an electrostatic charge image by adding and mixing titania-based inorganic fine particles (B) having an average particle size of 10 to 90 nm, wherein the mixing of the toner base particles and the inorganic fine particles is repeated. A method for producing an electrostatic image developing toner. 2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the mixing rise time of the mixing blade of the mixing blade is 3 seconds or more and 15 seconds or less. 3. A blade tip peripheral speed of the mixer is 10 m.
3. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the toner density is not less than 50 m / s and not more than 50 m / s. 4. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the number of mixing cycles is 3 or more and 10 or less. 5. The method for producing a toner for developing an electrostatic image according to claim 1, wherein each mixing time is 20 seconds or more and 60 seconds or less. 6. The method according to claim 1, wherein the inorganic fine particles (A) are added and mixed after the inorganic fine particles (A) are added and mixed.
6. The method for producing a toner for developing an electrostatic image according to any one of items 1 to 5. 7. The addition amount of the silica-based inorganic fine particles (A) is 1
The method for producing a toner for developing an electrostatic image according to any one of claims 1 to 6, wherein the content is not more than% by weight.