JP2609358B2 - Electrophotographic toner for negative charging - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a negatively charged electrophotographic toner frequently used in a laser beam printer, a digital copying system, and the like in recent years. The present invention relates to a negatively charged electrophotographic toner capable of forming a high-density image with a sharp hue and excellent image reproducibility without toner scattering.

(Prior Art) In the field of commercial electrophotographic copying and electrophotographic printing, a method of forming a positively charged electrostatic image is generally adopted in order to minimize the amount of ozone generated during charging. And
Therefore, as a developing toner used for developing the electrostatic image, a negative charging toner is widely used.

On the other hand, in recent years, laser beam printers and digital copiers have been developed, and in such image forming apparatuses,
The operation of writing a latent image on a negatively charged organic photoreceptor with a laser and performing reversal development with a negatively charged toner has been adopted, and a higher quality toner has been required for the negatively charged toner.

The developing toner is formed by granulating a resin composition containing a fixing resin, a colorant and a charge control agent as essential components to a toner particle size, generally an average particle size of 5 to 15 μm. In the case of a negative charging toner, a toner having a negative charge control action during frictional charging is used as a charge control agent.

In the conventional toner charge control method, the control of the average value of the toner charge amount of the entire toner is controlled by selecting the type of charge control agent and adjusting the amount of addition. However, in this method, even if it is possible to control the average value of the charge amount of the entire toner, it is very difficult to exactly control the distribution of the charge amount of the toner particles.

Conventionally, it is already known that a toner particle contains a plurality of charge control agents having a charging performance of opposite polarities. For example, JP-A-54-34243 discloses an electrostatic charge comprising toner and a carrier. An image developer is described in which the toner is a negatively chargeable toner containing a dye which is positively charged by friction with a carrier.

JP-A-57-196264 discloses an electrically insulating fixing medium, an electrically insulating magnetic one-component developer comprising a magnetic material powder and a charge control agent dispersed in the fixing medium. The developer is described, wherein the charge control agent comprises a combination of a weight ratio of a negative or positive charge control agent and a charge control agent having a polarity opposite thereto from 1: 0.05 to 1: 1.5. ing.

(Problems to be Solved by the Invention) In the conventional negative charging toner, the type and amount of the charge control agent are adjusted so that the average value of the charge amount is a value that can be sufficiently satisfied. In addition, the tendency that the distribution of the charge amount becomes considerably wide is inevitable. Of particular concern here is that
The charge amount is much higher than the average value, and a highly charged toner that is not consumed for development is necessarily generated at a certain frequency (distribution amount). Another problem is that a low-charged toner having a charge amount considerably lower than the average value and causing toner scattering is generated at a certain frequency.

The former highly charged toner particles are strongly adsorbed to the surface of the carrier particles and exist in a state in which they are hardly separated, and significantly impair the frictional charging performance of the carrier particles. Therefore, even if the toner has relatively few problems at the beginning of the development,
As the development time elapses, the ratio of the uncharged or low-charged toner increases, causing problems such as toner scattering, fogging, and image density reduction.

In the method of combining a positively chargeable dye (charge control agent) with a charge control agent for negative charging, which is found in the prior art, the distribution of the charge amount can be freely shifted to a higher charge amount side or a lower charge amount side. Even if the advantage of obtaining the toner can be obtained, this method is still sufficiently satisfactory from the viewpoint that the distribution of the toner charge amount is sharpened and the generation of the highly charged toner and the lowly charged toner is suppressed to a level that is negligible or negligible. It was not something you could do.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a negatively charged electrophotographic toner capable of preventing toner scattering, stabilizing the image density, and performing such a suitable development over a long period of time.

(Means for Solving the Problems) According to the present invention, in a negative charging electrophotographic toner containing a fixing resin, a colorant and a negative charging charge controlling agent, the negative charging charge controlling agent comprises: The following formula: CH ₂ = CX ¹ -CO-NH-X ² -SO ₃ H In the formula, X ¹ is a hydrogen atom or a methyl group, and X ² is a divalent hydrocarbon group having 1 to 6 carbon atoms. A copolymer of an acrylamide-based monomer and an addition-polymerizable monomer represented by the following formula, which is incompatible with the fixing resin, has dispersibility, and has a negative charge. As a charge control aid having a charge control action of the opposite polarity to the control agent, the following formula: In the formula, R represents a lower alkyl group or a benzyl group under the condition that at least one of them is a long-chain alkyl group or a long-chain alkenyl group, and at least two of them are a lower alkyl group or a benzyl group. a long chain alkyl group or long chain alkenyl group, a ^- is molybdate, tungstic acid, an anion of an oxygen acid selected from the group consisting of antimonate and bismuth acid, in the quaternary ammonium salt represented by Containing, the charge control agent and the charge control aid are from 1: 0.05 to 1: 1
Wherein the toner is present in the toner in a weight ratio of 0.5 to 5 parts by weight in total per 100 parts by weight of the fixing resin.

The molecular weight of the polymer as the charge control agent is 2000 to 15
000 range.

The polymer as the charge control agent is a copolymer of the sulfonic acid-containing acrylamide-based monomer and another addition-polymerizable monomer, and the sulfonic acid-containing acrylamide-based monomer is entirely On the other hand, it can be characterized in that it is contained in an amount of 2% by weight or more.

(Action) The electrophotographic toner for negative charging of the present invention contains a fixing resin, a colorant, a charge control agent for negative charging, and a charge control auxiliary agent as essential components. By forming a polymer containing a specific acrylamide-based monomer containing a sulfonic acid as a charge control agent and combining it with a specific quaternary ammonium-based charge control aid, extremely electric properties can be obtained. Which is superior in toner.

The charge control agent for negative charging is represented by the following formula: CH ₂ CCX ¹ —CO—NH—X ² —SO ₃ H In the formula, X ¹ is a hydrogen atom or a methyl group, and X ² has 1 to 6 carbon atoms. It is important that the polymer contains an acrylamide-based monomer represented by the following formula, which is a divalent hydrocarbon group. Such a charge control agent is uniformly dispersed in a fixing resin, The overall charging can be controlled.

The present invention also provides, in place of the conventionally used positively chargeable dye that is compatible with the fixing resin, a positively charge control substance that is incompatible with the fixing resin but is dispersible. It is important to combine it with a charge control agent for negative charge as a charge control aid. The charge control aid has the following formula: In the formula, R represents a lower alkyl group or a benzyl group under the condition that at least one of them is a long-chain alkyl group or a long-chain alkenyl group, and at least two of them are a lower alkyl group or a benzyl group. a long chain alkyl group or long chain alkenyl group, a ^- is molybdate, tungstic acid, an anion of an oxygen acid selected from the group consisting of antimonate and bismuthate, in represented quaternary ammonium salts Yes, such charge control aids are incompatible with the resin but are dispersible. When such a charge control agent is combined with the negative charge control agent, the charge amount of the toner can be suitably adjusted, and the distribution of the charge amount of the toner can be significantly sharper than the conventional one. As a result, the ratio of the highly charged toner and the lowly charged toner decreases. Highly charged toners have poor transferability to the photoreceptor, while lowly charged toners tend to cause toner scattering, but the negatively charged electrophotographic toner of the present invention results in the occurrence of such problems. Can be effectively suppressed.

FIG. 2 is a characteristic diagram showing the distribution of the amount of charge of the toner A using only the conventional charge control agent for negative charge (Experimental Example 3). FIG. 3 is a diagram showing the charge control agent for negative charge and the positive charge. Characteristic Distribution Chart of Charge Amount of Toner B Containing Neutral Dye (Experimental Example 4)
FIG. 1) and FIG. 1 are distribution characteristic diagrams of the charge amount of the electrophotographic toner C for negative charging according to the present invention (see Experimental Example 1).
It is. Table 1 below summarizes the characteristic values of the charge amount distribution described below for these toners A, B, and C.

In the toner A using the conventional negative charging control agent, the second
As shown in the figure, a large amount of highly charged toner in the a region exists, and a considerable amount of the oppositely charged toner and 0 charged toner in the d region are also included. Further, in the toner B of the prior art in which a positively chargeable dye is combined with a negatively chargeable control agent, the average value of the charge amount can be shifted to the lower charge amount side as shown in FIG. The width is almost the same as that of the toner A, and the amount of the high-charged toner in the area a is small but still present.
The presence ratio of the oppositely charged toner and the 0 charged toner in the region increases.

On the other hand, in the toner C of the present invention, as shown in FIG. 1, the amount of the toner in the appropriate charging areas b and c increases, and the width of the charging amount distribution becomes extremely narrow. It can be understood that the amount of the oppositely charged toner and the amount of the 0 charged toner in the d region can be reduced (eliminated here).

Table 1 shows that the above toners A, B, and C were used to continuously copy 1000 sheets using a laser beam printer LPX-1 (made by Mita Kogyo Co., Ltd.) (model changed to reversal development). Image density (ID) and image fog density (F
D) and the situation of toner scattering around the developing device was evaluated.

From FIGS. 1 to 3 and Table 1, it is confirmed that the toner of the present invention can be improved to a preferable charging characteristic capable of suppressing fluctuations in image density, image fogging and toner scattering.

In the toner of the present invention, the fact that the distribution of the charge amount becomes sharp by combining the charge control agent for negative charge and the charge control aid for positive charge of a fixing resin immiscible type is a fact of many experiments. It was found as a result phenomenon and the reason is not clear, but in the fixing resin,
Sufficient dispersion of the negative charge control agent and the charge control aid occurs, and the sulfonic acid group of the negative charge control agent and the quaternary ammonium of the charge control aid interact to sharpen the charge distribution curve. It is presumed that the number of high-charge toners and low-charge toners should be reduced. One of the serious drawbacks caused by combining a conventional positive charge control agent with a negative charge control agent as an auxiliary is that even if the charge of the toner particles is finally controlled to be negative, When the developer composed of the carrier and the carrier is stirred in the developing device, the rise of the charge is delayed. On the other hand, in the toner of the present invention in which the sulfonic acid-containing acrylamide-based charge control agent and the auxiliary agent are combined, the rise of the charge when the developer is started to be stirred and the charge is started,
It also has the advantage of being extremely fast.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments according to the present invention will be described.

Charge control aid The charge control aid used in the present invention is incompatible with the fixing resin, but has dispersibility and has a charge control action of a polarity opposite to that of the negative charge control agent. Which has the following formula: In the formula, R represents a lower alkyl group or a benzyl group under the condition that at least one of them is a long-chain alkyl group or a long-chain alkenyl group, and at least two of them are a lower alkyl group or a benzyl group. a long chain alkyl group or long chain alkenyl group, a ^- is molybdate, an anion of a tungstic acid, oxygen acid selected from the group consisting of antimonate and bismuth acid, in the quaternary ammonium salt is used represented Is done. These quaternary ammonium salts are particularly suitable for the purpose of sharpening the distribution of the charge amount without delaying the rise of the charge of the toner.

Charge control agent The charge control agent for negative charge used in combination with the charge control aid is represented by the following formula: CH ₂ C X ¹ -CO-NH-X ² -SO ₃ H In the formula, X ¹ is a hydrogen atom or X ² is a divalent hydrocarbon group having 1 to 6 carbon atoms, and is a copolymer of an acrylamide-based monomer represented by the following formula and an addition-polymerizable monomer. Here, the hydrocarbon group X ² may be either aliatic or aromatic. Specific examples include 3-acrylamido-3-methylbutylsulfonic acid, 2-acrylamido-2-methylbutylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and 2-acrylamido-methylsulfonic acid.

The molecular weight of the polymer as the charge control agent is 2,000
The polymer may be a copolymer of the sulfonic acid-containing acrylamide-based monomer and another addition-polymerizable monomer, and may be a sulfonic acid-containing acrylamide-based polymer. 2% by weight of monomer
It is desirable to include the above.

In the present invention, the charge control agent and the charge control aid
It is preferred to use 1: 0.05 to 1: 1, especially 1: 0.1 to 1: 0.7 weight ratio, and to use these combinations in total of 1 to 5 parts by weight, particularly 2 to 4 parts by weight per 100 parts by weight of the fixing resin. Should be present in an amount of

Fixing Resin As the fixing resin, a known fixing resin which is not compatible with the charge control assistant but exhibits dispersibility is used. Since these fixing resins charge the toner with a negative charge, it is desirable that the fixing resin has a tendency to be charged with a negative charge. For example, a styrene resin, an acrylic resin, or a styrene-acryl copolymer resin may be used. Commonly used.

As the styrene monomer used for these resins,
The following formula In the formula, R ₁ is a hydrogen atom, a lower (C 4 or less) alkyl group or a halogen atom, and R ₂ is a hydrogen atom or a substituent such as a lower alkyl group or a halogen atom. Such as styrene, vinyltoluene, α-methylstyrene, α-chlorostyrene, vinylxylene, and vinylnaphthalene. Among them, styrene is preferred.

On the other hand, as the acrylic monomer, the formula Wherein, R ₃ represents a hydrogen atom or a lower alkyl group, R ₄
Is a hydrogen atom or a substituted or unsubstituted alkyl group having up to 18 carbon atoms, such as ethyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, acrylic Acids, methacrylic acid and the like. As the acrylic monomer, in addition to those described above, other ethylenically unsaturated carboxylic acids or anhydrides thereof,
For example, maleic acid, fumaric acid, maleic acid, crotonic acid, itaconic acid and the like or anhydrides thereof can be used.

Styrene-acrylic copolymer resin is one of the suitable resin media, and styrene monomer (A) and acrylic monomer (B) are A: B = 50: 50-90. :Ten,
In particular, the range is preferably 60:40 to 85:15. Further, the resin used generally preferably has an acid value of 0 to 25. Further, from the viewpoint of fixability, it is preferable that the glass transition temperature (Tg) is 50 to 75 ° C.

Colorant As the colorant contained in the resin, the following inorganic or organic pigments and dyes can be used alone or in combination of two or more. Carbon blacks such as furnace black and channel black; iron blacks such as triiron tetroxide; titanium dioxide such as rutile or anatase; phthalocyanine green; cadmium yellow;
Pyrazolone red; Fast Violet B and the like.

Toner The particle diameter of the toner particles, as measured by a Coulter counter, is preferably in the range of 5 to 15 μm, particularly 7 to 12 μm in terms of volume-based median diameter, and the particle shape was produced by a melt-kneading / pulverization method. It may be amorphous or spherical, produced by a dispersion or suspension polymerization method.

The toner of the present invention exhibits excellent chargeability when used as a two-component magnetic developer in combination with a magnetic carrier known per se. As the magnetic carrier, a ferrite carrier or an iron powder carrier is used, and these can be used either uncoated or resin-coated. Generally, ferrite carriers are preferred.

Conventionally, as ferrite, for example, iron oxide zinc (ZnFe
₂ O ₄ ), yttrium iron oxide (Y ₃ Fe ₅ O ₁₂ ), cadmium iron oxide (CdFe ₂ O ₄ ), gadolinium iron oxide (Gd ₃ Fe
₂ O ₁₂ ), copper iron oxide (CuFe ₂ O ₄ ), lead iron oxide (PbFe
₁₂ O ₁₉ ), nickel iron oxide (NiFe ₂ O ₄ ), iron neodymium oxide (NdFeO ₃ ), barium iron oxide (BaFe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe ₂ O ₄ ), iron manganese oxide (MnFe ₂ O) ₄ ),
Sintered ferrite particles of one or more compositions, such as lanthanum iron oxide (LaFeO ₃ ), are used.
Soft ferrite containing at least one metal component selected from the group consisting of Cu, Zn, Mg, Mn and Ni, preferably two or more, such as copper-zinc-magnesium ferrite, is used. Ferrite is also suitably used in the present invention.

Various types of coating resins for magnetic carriers, such as acrylic resins, styrenic resins, silicone resins, fluorine resins, and various amino-modified resins, are known, but they positively control the charge of the resin-coated magnetic carrier. Accordingly, it is preferable that the toner charge is indirectly controlled to be negative. Of course, in the present invention, even if such a carrier coat resin layer does not exist, it is natural that the control of the charge is performed effectively and reliably. The carrier's saturation magnetization is
It is preferably in the range of 40 to 75 emu / g, especially 45 to 70 emu / g. As the magnetic carrier, a ferrite carrier that satisfies the above conditions, particularly a spherical ferrite carrier, is preferable, and its particle size is 20 to 140 μm, particularly 50 to 100 μm.
m is desirable.

The mixing ratio between the toner and the magnetic carrier varies depending on the physical properties of the toner and the magnetic carrier, but is preferably in the range of generally 1:99 to 10:90, more preferably 2:98 to 5:95 by weight. . Further, it is generally desirable that the electric resistivity of the whole developer is in the range of 5 × 10 ^{9 to} 5 × 10 ¹² Ω · cm, preferably 5 × 10 ^{9 to} 5 × 10 ¹¹ Ω · cm.

In developing an electrostatic image, after mixing the toner and the magnetic carrier, a magnetic brush of a predetermined length is formed on a developing sleeve having a magnet roll therein, and the magnetic brush and a photoconductor having an electrostatic image are formed. The magnetic brush and the electrostatic image holding photoconductor are brought close to each other by rubbing or in an electric field to which an oscillating electric field is applied.

Measurement of Charge Amount Distribution A charge amount measurement device for toner particles will be described. As shown in FIG. 6, the charge amount measurement device includes a separation unit 2 for separating toner from a developer in a cylindrical housing 1; It has a measuring unit 3 for measuring the charge amount distribution of the separated toner, and a suction device 11 such as an air pump.

The separating unit 2 and the measuring unit 3 are separated by a partition plate 7, and the housing 1 is located slightly below the partition plate 7.
A communication hole 1a for introducing air into the housing 1
Is provided. An air rectifying filter 8 is provided slightly below the communication hole 1a.

The separating unit 2 is provided with the developer held on the magnet 4,
The compressed air is blown by the air needle 5, and only the lightweight toner is blown up and scattered, leaving the carrier magnetically attracted to the magnet 4.

A funnel 6 supported by a partition plate 7 is provided between the separation unit 2 and the measurement unit 3. The receiving port 6d at the upper end of the funnel 6 protrudes above the partition plate 7, and the front recess 6a at the lower end penetrates the filter 8 and faces the measuring unit 3 side.

The measuring unit 3 applies a DC power source B to the pair of electrode rods 9a and 9b embedded in the side wall of the housing 1,
A horizontal parallel electric field is formed between the electrode rods 9a and 9b. 10 is a filter.

The suction device 11 is connected to the communication hole 1a from outside the housing 1.
A main airflow that flows to the measuring section 3 through the rectifying filter 8 and the airflow that sucks the toner into the funnel 6 are formed above the funnel 6.

According to this charge amount measuring device, the toner particles separated by the separating unit 2 and collected by the funnel 6 and introduced into the measuring unit 3 fall vertically by the airflow by the suction device 11, and fall into the electrode rod 9a, It passes between 9b and lands on the filter 10. At this time, the toner particles fall in the horizontal parallel electric field between the electrode rods 9a and 9b while receiving the horizontal Coulomb force H and the vertical gravity V according to the charge amount. The light is dispersed on the filter 10 at positions corresponding to the mass and the charge amount. Then, from the distribution of the falling positions of the toner particles, the charge amount distribution of the toner is calculated by image processing.

(Example 1) The composition of the negative charging toner is adjusted as follows.

Fixing resin: 100 parts by weight of styrene-acryl copolymer, colorant: 5 parts by weight of carbon black, charge control agent for negative charging: styrene and 2-acrylamide-
Copolymer with 2-methylpropanesulfonic acid (composition ratio =
20: 1, weight average molecular weight (Mw): 8000) 2 parts by weight, charge control auxiliary agent: 0.5 part by weight of a quaternary ammonium salt of the following formula, The above materials were melt-kneaded by a twin-screw extruder, and the kneaded product was cooled, pulverized and classified to obtain a toner having an average particle diameter of 11 μm. Then, this toner and a resin-coated ferrite carrier having an average particle diameter of 85 μm are mixed and stirred at a toner concentration of 4.5% to form a developer, and the toner charge distribution measuring device shown in FIG. 6 is used. The charge amount distribution was measured. FIG. 1 shows the result.

Then, the above developer was modified with a laser beam printer LPX-1 manufactured by Mita Kogyo Co., Ltd. equipped with an organic photoreceptor for negative charging (improved to a reversal development method) (photoreceptor surface potential:-
(700 V, developing bias potential: -500 V), and continuous image formation was performed on 1000 sheets, and the image characteristics were observed. As a result, a good image was obtained without any decrease in image density, image fogging, and toner scattering shown in Table 1. Was. Further, when the continuous image formation of 50,000 sheets was performed and the fluctuation of the toner charge amount distribution was traced,
As shown in the figure, the toner charge amount distribution remained good without any change even after 10,000 sheets.

(Experimental example 2) Styrene and 2-acrylamide-2 as charge control agents
Copolymer with methyl butyl sulfonic acid (composition ratio = 20:
1. A toner was prepared in the same manner as in Experimental Example 1, except that the weight average molecular weight (Mw); 10000) was changed to 2 parts by weight and a charge controlling agent was changed to 0.5 part by weight of a quaternary ammonium salt represented by the following formula. .

Thereafter, a developer was obtained in the same manner as in Experimental Example 1, and the change in the toner charge amount distribution during continuous image formation of 50,000 sheets was followed.
As a result, a good image was obtained as in Experimental Example 1, and there was no toner scattering in the apparatus. The toner charge amount distribution was similarly measured before printing and after printing 5,000 sheets.
It was as sharp as.

(Experimental example 3) It carried out similarly to Experimental example 1 except not having used the charge control auxiliary agent. FIG. 2 shows the charge amount distribution of the obtained toner. Observation of image characteristics by continuous image formation of 5000 sheets,
The image density was unstable, and image fogging and toner scattering occurred.

(Experimental Example 4) Instead of the charge control aid, CI compatible with the fixing resin
Solvent was performed in the same manner as in Experimental Example 1 except that 2 parts by weight of Yellow 56 was used. FIG. 3 shows the charge amount distribution of the obtained toner. In the observation of image characteristics by forming 5000 continuous images, the image density was unstable and the image density sometimes dropped. Further, image fogging and toner scattering also occurred.

(Experimental Example 5) The same operation as in Experimental Example 1 was carried out except that 2 parts by weight of a chromium-containing monoazo dye was used as a negative charge control agent. FIG. 5 shows the charge amount distribution of the obtained toner. In addition, as a result of observing the image characteristics by forming 5,000 continuous images, a good image was obtained in the initial stage and no toner was scattered in the apparatus, but at the end (after 4500 sheets), a small image was obtained. Fog and variations in image density were observed. FIG. 5 shows the charge amount distribution before printing and the charge amount distribution after printing. From the figure, it can be understood that the sharp charge amount distribution at the initial stage becomes broad with the printing durability, and defective toner is generated.

(Effects of the Invention) As described above, according to the present invention, a sulfonic acid-containing acrylamide-based polymer and a specific quaternary ammonium are used as a negative charge control agent and a charge control aid, and a negative charge electrophotographic toner is used. The resulting toner has excellent electrical characteristics, that is, a sharp distribution curve of the charge amount of the toner particles, and the toner scatters very little in the apparatus and forms a high-density image. Can. In addition, good images can be provided over a long period of time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a characteristic curve of a toner charge amount distribution of the present invention, and FIG. 2 is a diagram showing a characteristic curve of a toner charge amount distribution using a negative charge control agent alone. FIG. 3 is a graph showing a characteristic curve of a charge amount distribution of a toner using a negatively chargeable charge controlling agent and a positively chargeable compatible dye, and FIG. 4 is a charge amount distribution of the toner of the present invention. FIG. 5 is a diagram showing a characteristic curve of a charge amount distribution of a toner using a metal-containing monoazo dye as a charge control agent for negative charging, and FIG. FIG. 3 is a schematic layout diagram of a charge amount measuring device used for measuring a charge amount distribution.

Continuation of the front page (72) Inventor Akihiro Watanabe 1-2-28 Tamazo, Chuo-ku, Osaka-shi, Osaka Inside Mita Industry Co., Ltd. (72) Inventor Yoshihisa Kuramae 1-2-28 Tamazo, Chuo-ku, Osaka-shi, Osaka Mita Kogyo Co., Ltd. (56) References JP-A-2-22670 (JP, A) JP-A-63-184762 (JP, A) JP-A-2-167565 (JP, A) JP-A 64-54 ( JP, A) JP-A-2-236565 (JP, A) JP-A-63-68848 (JP, A)

Claims (3)

(57) [Claims] 1. A negatively chargeable electrophotographic toner containing a fixing resin, a colorant and a negatively chargeable charge control agent, wherein the negatively chargeable charge control agent is represented by the following formula: CH ₂ = CX ¹ -CO- during NH-X ² -SO ₃ H type, X ¹ is a hydrogen atom or a methyl group, X ² is C 1 -C
A copolymer of an acrylamide-based monomer represented by the formula: and an addition-polymerizable monomer, which is a divalent hydrocarbon group of from 6 to 6, which is incompatible with the fixing resin, As a charge control aid having dispersibility and a charge control action of the opposite polarity to the charge control agent for negative charge, the following formula: Wherein R is at least one of which is a long-chain alkyl group or a long-chain alkenyl group, provided that at least two of them are a lower alkyl group or a benzyl group.
Lower alkyl group, a benzyl group, a long chain alkyl group or long chain alkenyl group, A ^- represents an anion of an oxygen acid selected from the group consisting of molybdate, tungstate, antimony acid and bismuth acid, in formula A quaternary ammonium salt, wherein the charge control agent and the charge control aid are in a weight ratio of 1: 0.05 to 1: 1 and a total of 0.5 to 5 parts by weight per 100 parts by weight of the fixing resin. 1. An electrophotographic toner for negative charging, wherein the toner is present in the toner. 2. The negatively chargeable electrophotographic toner according to claim 1, wherein the polymer as the charge control agent has a molecular weight in the range of 2,000 to 15,000. 3. A copolymer of a sulfonic acid-containing acrylamide monomer and an addition-polymerizable monomer as the charge control agent, wherein the sulfonic acid-containing acrylamide monomer is added to the whole. The negatively chargeable electrophotographic toner according to claim 1, which contains 2% by weight or more.