JPH04195157A - Yellow toner - Google Patents

Abstract

PURPOSE:To obtain superior electric characteristics by using a benzidine pigment as a colorant and an acrylamide polymer having sulfonic acid groups as negatively chargeable charge controller and a specified quaternary ammonium as an auxiliary charge controller in combination with the yellow toner. CONSTITUTION:The toner contains the benzidine type pigment as the colorant and as the negatively chargeable charge controller the polymer having an acrylamide type monomer of formula I (R' is H or a lower hydrocarbon group and at least one of S1 and S2 is a hydrocarbon group having a sulfonic acid) and as the auxiliary charge controller incompatible with the fixing resin but dispersible in it and having a charge controlling action in polarity reverse to the negatively chargeable charge controller the quaternary ammonium of formula II (at least one of R is a long-chain alkyl group and the others are lower alkyl groups), thus permitting the obtained toner to have superior electric characteristics.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a negatively charged yellow toner that has been frequently used in laser beam printers, digital copying systems, etc. in recent years, and is mainly used for full color development. The present invention relates to a yellow toner that does not cause toner scattering during use, has a clear hue, has excellent image reproducibility, can form high-density images, and can exhibit sufficient reproducibility in full-color development.

(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. Therefore, negatively charged toner is widely used as the developing toner used to develop this electrostatic image.

On the other hand, in recent years, the development of laser beam printers and digital copying machines has progressed, and in these image forming devices, a latent image is written on a negatively charged organic photoreceptor using a laser.
Reversal development using negatively charged toner has been adopted, and higher quality negatively charged toner is now required.

The developing toner is made 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 μ-. In the case of a negatively charged toner, as a matter of course, a charge control agent having a negative charge control effect during triboelectric charging is used.

In conventional toner charge control systems, the average value of the toner charge amount for the toner as a whole is controlled by selecting the type of charge control agent and adjusting the amount added. However, with this method, although it is possible to control the average value of the charge amount of the toner as a whole, it is difficult to strictly control the distribution of the charge amount of the toner particles.

Conventionally, it has already been known that toner particles contain a plurality of charge control agents having charging properties of opposite polarity. A developer for electrostatic images is described in which the toner is a negatively charged toner containing a dye that becomes positively charged by friction with a carrier.

JP-A-57-196264 discloses an electrically insulating magnetic component developer comprising an electrically insulating fixing medium, a magnetic material powder dispersed in the fixing medium, and a charge control agent. The charge control agent is a negative or positive charge control agent and a charge control agent of opposite polarity in a ratio of 1:0.0.
A developer is described which is characterized in that it consists of a combination with a weight ratio of 5 to 1:1.5.

Further, recently, full-color development has been carried out in which an image is formed by superimposing magenta, cyan, yellow, and black color toners. In such full-color toners, organic colorants are mainly used as colorants in cyan toner, magenta toner, and yellow toner, and carbon black is mainly used as a colorant in black toners. 0ru.

(Interlayer point to be solved by the invention) In conventional negatively charged toners, the type and amount of charge control agent added are adjusted so that the average value of the charge amount is a sufficiently satisfactory value. However, the distribution of the amount of charge tends to become quite wide. A particular problem here is that the amount of charge is considerably higher than the average value, and highly charged toner that is not consumed for development inevitably occurs at a frequency (amount of distribution). Another problem is that the amount of charge is considerably lower than the average value, and low charge toner that causes toner scattering occurs frequently.

The former highly charged toner particles are strongly electrically adsorbed to the surface of the carrier particles and exist in a state where they are difficult to separate from, significantly impairing the triboelectric charging performance of the carrier particles. For this reason, even if the toner has relatively few interlayers at the beginning of development, as the development time progresses, the ratio of uncharged to lightly charged toner increases, causing toner scattering, fogging, and image formation. Problems such as a decrease in concentration will occur.

In the method of combining a positively chargeable dye (charge control agent) with a charge stabilizing agent for negative charge, which is seen in the prior art, the charge amount distribution can be shifted quite freely to the high charge amount side or to the low charge amount side. However, this method is still not fully satisfactory from the viewpoint of sharpening the distribution of toner charge amount and suppressing the generation of highly charged toner and low charged toner to a negligible level. It was not possible.

Furthermore, organic colorants are used in color toners, but they are often denatured by mechanical impact force during stirring operations in the developing device and the resulting heat, which causes changes in the charging characteristics of the toner. However, even if the charge amount distribution is sharp and good in the initial process, it may not be possible to maintain that state.

In addition, a desired color image (full color image) is obtained by overlapping each color toner (cyan, yellow, magenta), but if the charging characteristics of the toner fluctuate, the area to be developed (transferred) may The toner is no longer developed (transferred) and the desired color is no longer reproduced.

Therefore, an object of the present invention is to provide a yellow toner that prevents toner scattering, stabilizes image density, and allows suitable development over a long period of time.

Another object of the present invention is to provide a yellow toner that has little discoloration over a long period of time and has excellent reproducibility during full color development.

(Means for Solving the Problems) According to the present invention, in a negatively charged electrophotographic toner containing a fixing resin 1 colorant and a negatively charged charge control agent,
The coloring agent is a benzidine-based pigment, and the negative charge control agent is represented by the following formula % (R' is hydrogen or a lower hydrocarbon, and at least one of SI and S2 is a sulfonic acid-containing hydrocarbon.) A polymer containing an acrylamide monomer of
In addition to the negative charge control agent, R of the following formula is incompatible with the fixing resin but has monodispersity and has a charge control action of opposite polarity to the charge control agent for negative charge. -N''-R-A- (wherein R is a long-chain alkyl group or a long-chain alkenyl group, at least 21 of which are long-chain alkyl groups or long-chain alkenyl groups,
A lower alkyl group, provided that m1 is a lower alkyl group or a benzyl group.

It is a benzyl group, a long-chain alkyl group, or a long-chain alkenyl group, and A represents an anion. ) A yellow toner is provided, characterized in that it contains a charge control aid.

In the yellow toner, the charge control agent and the charge control aid are present in a weight ratio of 1:0.05 to 1:1, and in a total amount of 0.5 to 5 parts by weight per 100 parts by weight of the fixing resin. can be characterized by

The molecular weight of the polymer as the charge control agent may be in the range of 2,000 to 15,000.

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

(Function) The yellow toner of the present invention contains a fixing resin 1 colorant, a charge control agent for negative charging, and a charge control aid as essential components. By using a specific acrylamide-based polymer containing sulfonic acid, by combining this with a specific 1!4-quaternary ammonium-based charge control agent, and by using a benzidine-based pigment as a coloring agent, extremely We have discovered a toner with excellent electrical properties.

Charge control for negative charging is CO3-CR'-CO-N5IS
2 (R' is hydrogen or a lower hydrocarbon, and at least one of S and S2 is a sulfonic acid-containing hydrocarbon). The control agent can be uniformly dispersed in the fixing resin to control the charging of the entire resin.

The present invention also uses a positively charge control substance that is incompatible with the fixing resin but has dispersibility, instead of the conventionally used positively chargeable dye that is compatible with the fixing resin. ,
As a charge control aid, it is important to combine it with a charge control agent for negative charging. The charge control auxiliary agent has the following formula: Under the condition that it is an alkyl group or a benzyl group, it is a lower alkyl group, a benzyl group, a long-chain alkyl group, or a long-chain alkenyl group, and A represents an anion. The control aid is incompatible with the resin but dispersible. By combining such a charge control agent with the charge control agent for negative charging, the amount of charge on the toner can be suitably adjusted, and the distribution of the amount of charge on the toner can be made significantly sharper than that of conventional ones. ,
As a result, the ratio of highly charged toner and lowly charged toner decreases.

Highly charged toner has poor transferability to the photoreceptor, and lowly charged toner tends to cause toner scattering.
As a result, the yellow toner of the present invention.

The generation of such an interlayer can be effectively suppressed.

Furthermore, it is important for yellow toner to have such electrical properties. This may occur if yellow toner is deposited in an unnecessary area during the development and transfer process of a full-color image, but if low-charge toner adheres (exists) or if high-charge toner is not sufficiently transferred to the image area (transfer area), overlapping occurs. This is because the colors of the resulting image will change and the original will no longer be faithfully reproduced.

In the present invention, it is also important to use a benzidine-based raw material as a coloring agent. When a benzidine-based raw material is used as a colorant in a toner in combination with the charge control agent and charge control aid described above, denaturation due to impact force or heat is suppressed even during continuous stirring operations, thereby eliminating fluctuations in charge distribution. be able to.

Attached drawing 1i2@ is a time distribution diagram of the charge amount of toner A using only a conventional charge control agent for negative charging (Experimental Example 3), and FIG. 3 is a graph showing the charge control agent for negative charging and conventional positive charging. A characteristic diagram of the distribution of the charge amount of the toner B containing the color dye (see Experimental Example 4), and FIG. It is. Further, Table 1 below summarizes the characteristic values of the charge amount distribution, which will be described later, for these toners A-B and C.

In toner A using a conventional negative charge control agent, jI2
As shown in the figure, there is a large amount of highly charged toner in the d range, and a considerable proportion of oppositely charged toner and O-charged toner in the d range are also included. Furthermore, in Toner B of the prior art in which a conventional positively chargeable dye is combined with a negative charge 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 Toner A,
Although the amount of highly charged toner in the d region decreases, it still exists, and the ratio of the oppositely charged toner and O-charged toner in the d region increases.

For this nine, CH,=CR'-CO-NS,S2
Toner C of the present invention, in which a polymeric negative charge control agent containing I! and a 1Mn-incompatible positive charge control substance for fixing are combined as auxiliary agents, has I! As shown in Figure 1, the amount of toner in the appropriate charge range C increases, making the charge distribution width significantly narrower, and the amount of highly charged toner in the d range and oppositely charged toner or zero charge toner in the d range decreases. (It is missing here) It is understood that it can be done.

Table 1 shows the above toners A, B, and C, and a laser beam printer LPX-1 (manufactured by Sanda Kogyo Co., Ltd., trade name) modified machine (improved to reversal development method) was used to produce 1,000 yen.
The image density (ID), image fog density (FD), and toner scattering around the developing device were evaluated when continuous copying of sheets was performed.

From Figures 111 to 3 and Table 111 of Table 1, it is confirmed that the toner of the present invention can be improved to have preferable charging characteristics that can suppress fluctuations in image density, image fogging, and toner scattering.

In addition, Figure jI4 shows the initial toner charge amount distribution when a 50,000-sheet copying test was conducted using the toner C of the present invention (see Experimental Example 1) and the toner charge amount distribution after 50,000 sheets were copied, I! Figure 5 shows colorants other than benzidine pigments (here, C, I, Pigment Yellow 138, Experimental Example 5).
FIG. 3 is a diagram showing the initial toner charge amount distribution when a 50,000-sheet copying test was conducted using Toner D of (Reference) and the toner charge amount distribution after 50,000 sheets were copied. As is clear from the figure, Toner C of the present invention, which uses benzidine-based raw materials, can maintain a sharp charge distribution over a long period of time, while Toner D, which uses colorants other than benzidine-based pigments, can maintain a sharp charge distribution over a long period of time. The copying test shows that the initially sharp charge amount distribution becomes broad and a large number of defective toners are produced. This means that the toner of the present invention does not cause fluctuations in image density, fog, or toner scattering, not only during the initial stage of development, but also when development is performed for a long period of time, and is extremely effective in preventing deterioration of charging characteristics. It shows that there is.

In the toner of the present invention, the fact that the charge amount distribution becomes sharp by combining the charge control agent for negative charge and the charge control agent for positive charge that is incompatible with the fixing resin has been confirmed by numerous experiments. This was discovered as a fruiting phenomenon, and although the reason is not clear, the charge control agent for negative charging and the charge control aid are sufficiently dispersed in the fixing resin, and the charge control agent for negative charging is I of sulfonic acid group and charge control aid! It is presumed that quaternary asiamonium interacts with each other to sharpen the charge distribution curve and reduce the number of highly charged toners and lowly charged toners.

Furthermore, one of the serious drawbacks that arises when a conventional positive charge control agent is combined with a negative charge control agent as an auxiliary agent is that even if the charge of the toner particles is ultimately controlled to be negative, the toner particles When a developer consisting of a carrier and a carrier is stirred in a developing device, the charge rises slowly. On the other hand, the toner of the present invention, which combines a sulfonic acid-containing acrylamide charge control agent and the above-mentioned auxiliary agent, has the advantage that the charge rises extremely quickly when charging starts after stirring the developer. That's what you get.

(Preferred embodiment of the invention) One embodiment of the present invention will be described below.

1 milk indigo! The charge control aid used in the present invention is incompatible with the fixing resin, but has dispersibility and a charge control action of opposite polarity to that of the charge control agent for negative charging. Specifically, quaternary ammonium salts are used.

Suitable quaternary ammonium salts include the formula % Formula % wherein R is at least lII of which is a long-chain alkyl group or long-chain alkenyl group, and at least two of which are lower alkyl groups or benzyl groups. is a lower alkyl group, a benzyl group, a long-chain alkyl group or a long-chain alkenyl group, and A 1 represents an anion, particularly preferably an oxyacid anion.

Compounds represented by can be mentioned. Examples of the oxyacid anion include phosphorus oxyacids such as orthophosphoric acid and pyrophosphoric acid, and anions such as molybdic acid, tungstic acid, antimonic acid, and bismuth acid. These quaternary ammonium salts are particularly suitable for the purpose of sharpening the charge amount distribution without slowing down the charge rise of the toner.

The negative charge control agent used in combination with the above charge control aid is expressed by the following formula % (R' is hydrogen or a lower hydrocarbon, and at least one of Sl and S2 is a sulfonic acid-containing hydrocarbon. ) is a polymer consisting of acrylamide monomers.

The substituent directly connected to the N-position is a sulfonic acid-containing hydrocarbon, and the hydrocarbon may be Alifatec or Aroman Aromatchi Ink, and is particularly preferably a lower hydrocarbon having 1 to 6 carbon atoms. Specifically, 3-acrylamide-3
-Methylbutylsulfonic acid, 2-acrylamide-2-
Examples include methylbutylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and 2-acrylamidomethylsulfonic acid.

Further, the molecular weight of the polymer as the charge control agent is 200.
The range is preferably 0 to 15,000, and the polymer may be a copolymer of the sulfonic acid-containing acrylamide monomer and another addition polymerizable monomer, and the sulfonic acid-containing acrylamide The system monomer is 2 for the whole
It is desirable that the content is at least % by weight.

In the present invention, the above-mentioned charge control agent and charge control auxiliary agent are combined in 1
: 0.05 to 1:1, especially 1 : 0.1 to
A weight ratio of 1:0.7 is preferably used, and the combination is preferably present in a total amount of 1 to 5 parts by weight, especially 2 to 4 parts by weight per 100 parts by weight of fixing resin.

Fixing resin As the fixing resin, a known fixing resin that is not compatible with the charge control aid but exhibits dispersibility is used. Since these fixing resins charge the toner negatively, it is desirable that they have a tendency to be negatively charged. For example, styrene resin, acrylic resin, or styrene-acrylic copolymer resin is used. Commonly used.

The styrene monomer used in these resins is as follows: In the following formula, R1 is a hydrogen atom, a lower alkyl group (having 4 or less carbon atoms), or a halogen atom, and R2 is a hydrogen atom or a lower alkyl group, Examples of monomers represented by the following, which are substituents such as halogen atoms, include styrene, vinyltoluene, α-methylstyrene, α-chlorostyrene, vinylxylene, and vinylnaphthalene.

Among these, styrene is preferred.

On the other hand, as an acrylic monomer, in the formula, R3 is a hydrogen atom or a lower alkyl group, and 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-ethyl These include hexyl methacrylate, acrylic acid, and methacrylic acid. As the acrylic monomer, in addition to those mentioned above, other ethylenically unsaturated carboxylic acids or their anhydrides, such as maleic acid, fumaric acid, maleic acid, crotonic acid, itaconic acid, etc., or their anhydrides may be used. You can also do it.

Styrene-acrylic copolymer resin is one of the suitable resin media, and the styrene monomer (A) and acrylic monomer (B) have a ratio of A:B=50:50 to 90. :10, especially in the range of 60:40 to 85:15. Further, it is preferable that the resin used generally has an acid value of 0 to 25. Further, from the viewpoint of fixing properties, it is preferable that the toner has a glass transition temperature (Tg) of 50 to 75°C.

As the colorant contained in the colorant resin, one or more yellow colorants containing a benzidine pigment as a main component are used.

Specifically, the benzidine pigments include C and I.

Gment Yellow 13 (Benzidine Yellow GR)
, C,I, Pigment Yellow 14 (Palcan Fast Yellow G), C,1, Pigment Yellow 17, C,I, Pigment Yellow 55,
Examples include C,I, Pigment Yellow 12 C,1, and Pigment Yellow 83.

Further, the benzidine pigment described above may be used as a main component, and other yellow colorants such as yellow lead, titanium yellow, quinoline yellow lake, and other colorants may be used in combination.

By using benzidine pigment as the main ingredient.

The yellow color is well developed, the hue is clear, and the color does not fade and is durable.

Toner The particle size of the toner particles is preferably in the range of 5 to 15 μm, particularly 7 to 12 μm, as measured by a volumetric median diameter using a Coulter counter.

Further, the particle diameter may be amorphous particles produced by a melt mixing/pulverization method, or spherical particles produced by a dispersion or suspension polymerization method.

By combining the toner of the present invention with a magnetic carrier known per se and using it as a two-component magnetic developer,
Excellent charging properties are exhibited. As the magnetic carrier, ferrite carriers and iron powder carriers are used, and these carriers may be uncoated or resin-coated. Ferrite carriers are generally preferred.

Conventional ferrites such as iron zinc oxide (ZnFe2
0. ), iron yttraum oxide (Y3F+!5012),
Cadmium iron oxide (CdFe2O,), gadolinium iron oxide (Gd3Fe2Q, 2), iron steel oxide (CuFe2O
), iron oxide complex (PbFe+20+e), iron nickel oxide (NiFe2O,), iron neodymium oxide (NdFe0
s), barium iron oxide (BaFe120+o) - magnesium iron oxide (gFe20a), iron manganese oxide (
Sintered ferrite particles with a composition consisting of one or more of MnFe204), lanthanum iron oxide (Lace'3), etc. are used, and in particular Cu, Zn, Mg, M
Soft ferrites containing at least one, preferably two or more metal components selected from the group consisting of n and nickel, such as copper-zinc-magnesium ferrite, are used. It is also suitably used in the invention.

Coating resins for magnetic carriers include acrylic resin, styrene resin, silicone resin, fluorine resin,
Various amino-modified resins are known, but
Preferably, the toner charge is indirectly controlled to be negative by controlling the charge of the resin-coated magnetic carrier to be positive.

Of course, in the present invention, charge control can be performed effectively and reliably even without such a carrier coat resin layer. The saturation magnetization of the carrier is 40 to 75 et
ru/g, preferably in the range of 45 to 70 emu/g. The magnetic carrier is preferably a ferrite carrier that satisfies the above conditions, especially a spherical ferrite carrier, whose particle size is 4*20 to 140 μm.
m, particularly i, is preferably in the range of 50 to 100 μm.

The mixing ratio of toner and magnetic carrier varies depending on the physical properties of the toner and magnetic carrier, but the weight ratio is generally 1:99 to 10:90, particularly 2:98 to 5:9.
It is desirable that it be within the range of 95. In addition, the electrical resistivity of the developer as a whole is 5X10" to 5X101
2Ω' CI, preferably 5 x 10' to 5 x 1011
It is generally desirable that it be in the range of Ω·cm.

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

Charge Amount To explain the charge 1 measuring device for toner particles on cloth, as shown in FIG.
It includes a separating section 2 that separates toner from developer, a measuring section 3 that measures the charge amount distribution of the separated toner, and a suction device 10 such as an air pump.

The separation section 2 and the measurement section 3 are separated by a partition plate 7, and a communication hole 1a for introducing air into the housing 1 is provided in the side wall of the housing 1 slightly below the partition plate 7.
is provided. An air rectifying filter 8 is disposed slightly below the communication hole 1a.

The separating unit 2 uses an air needle S to blow compressed air onto the developer held on the magnet 4, leaving the carrier magnetically attracted to the magnet 4 and moving only the lightweight toner upward. Blow up and scatter.

A funnel 6 supported by a partition plate 7 is provided between the separating section 2 and the measuring section 3. The receiving opening 6d at the upper end of this funnel 6 projects above the partition plate 7, and the tip recessed part 6a at the lower end penetrates the filter 8 to form a total of 1!1 part 3.
It's on the side.

The measurement unit 3 applies a DC type mR to a pair of electrode rods 9a, 9b embedded in the side wall of the housing 1, thereby forming a horizontal parallel electric field between the electrode rods 9a, 9b.

10 is a filter.

The suction device W11 connects the communication hole 1 from the outside of the housing 1.
A and the rectifying filter 8 to form a main air flow that flows to the measuring section 3, and at the same time, an air flow that sucks the toner into the funnel 6 is formed above the funnel 6.

According to this charging Ji8 constant device, the toner particles separated by the separating section 2, collected by the funnel 6, and introduced into the measuring section 3 fall vertically on the airflow by the suction device [11], and fall vertically to the electrode rod 9a. .

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 being subjected to a Coulomb force H in the horizontal direction depending on the amount of charge and gravity V in the vertical direction, so that the toner particles are They are dispersed on the filter 10 at positions corresponding to their mass and charge amount. Then, from the distribution of the falling positions of the toner particles, the toner charge amount distribution is calculated by image processing.

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

Fixing layer stack fN: 100 parts by weight of styrene-acrylic copolymer, Colorant: C, 1, Pizment, Yellow@17, 5 parts by weight, Negative electric layer charge control agent: Styrene and 2- acrylamide
Copolymer with 2-methylpropanesulfonic acid (composition ratio =
20:1, weight average molecule ji (Nw): 8000
) 2 parts by weight, charge control aid: 0.5 quaternary ammonium salt of the following formula
% or more of the mixture was melted and kneaded to 1M using a twin-screw extruder, and the kneaded product was cooled, then crushed and classified to obtain a toner having an average particle size of 11 μm. Then, this toner and a resin-coated ferrite carrier having an average particle diameter of 85 μm were mixed to a toner concentration of 4.
A developer was prepared by mixing and stirring at 5%, and the charge amount distribution was measured using the toner charge amount distribution measuring device shown in FIG. The results are shown in Figure 1.

Next, the developer was applied to a modified Sanda Kogyo laser beam printer LPX-1 equipped with a negatively charged organic photoreceptor (
(Improved to reversal development method) (+!8 Light body surface potential knee 700V, development bias potential knee 500V) l: After continuous layering and continuous image formation of 1000 sheets, the image characteristics were observed, and the results are shown in Table 1. Decreased image density and image fog,
The image was good with no toner scattering. Furthermore, 500
When we tracked the fluctuations in the toner charge amount distribution by continuously forming 00 images, we found l! As shown in FIG. 4, the toner charge amount distribution did not change and remained good even at the initial stage and after 10,000 sheets were printed.

(Experimental Example 2) 5 parts by weight of C,1,Pigment (Bicoument) and Yellow 13 were used as colorants, and a copolymer of styrene and 2-acrylamido-2-methylbutylsulfonic acid ( Composition ratio = 20:1,
A toner was prepared in the same manner as in Experimental Example 1, except that 2 parts by weight of the weight average molecular weight (Mw: 10,000) and 0.5 parts of a quaternary ammonium salt of the following formula as a charge control aid were changed. It was created.

Thereafter, a developer was obtained in the same manner as in Example 1, and image characteristics were observed and fluctuations in toner charge amount distribution were tracked. As a result, the toner charge amount distribution was sharp, and the charge amount distribution with almost no high charge range toner or O to reversely charged toner was maintained, and images were always formed satisfactorily.

(Experimental Example 3) The same procedure as in Experimental Example 1 was conducted except that a charge control aid was used. FIG. 2 shows the charge amount distribution of the obtained toner. Furthermore, when observing the image characteristics after continuous image formation on 1000 sheets, the image density was unstable, and image fogging and toner scattering also occurred.

(Experimental Example 4) Instead of the charge control aid, C, 1 which is compatible with the fixing resin
．． 5olvent (Solhento),Yell
The same procedure as in Experimental Example 1 was conducted except that 0.5 parts by weight of OW (Yellow) 56 was used.

The charge amount distribution of the obtained toner is shown in Figure 313.

Further, when observing image characteristics after continuous image formation on 1000 sheets, image fogging and toner scattering were severe.

Further, although the image density was satisfactory to some extent, density unevenness occasionally occurred.

(Experimental Example 5) The same procedure as in Experimental Example 1 was conducted except that 5 parts by weight of C, 1, Pigment Yellow 138 was used as the coloring agent. The charge amount distribution of the obtained toner is shown in FIG. Also, 1000
Observe the image characteristics by continuously forming images on 500 sheets.
Figure 5 shows the toner charge amount distribution after image formation on 00 sheets (-
(dotted chain line). In the image formation of 1000 sheets, good images were obtained as in Experimental Example 1. However, from 9 on 7,000 sheets, the toner charge amount distribution worsened and became broad, and the image per 10,000 sheets also became poor.

(Experimental Example 6) The same procedure as in Experimental Example 1 was conducted except that 2 parts by weight of a chromium-containing monoazo dye was used as the negative charge control agent. The charge amount distribution of the obtained toner is shown in FIG. In addition, we observed the image characteristics by continuous image formation on 1000 sheets, and
The toner charge amount distribution obtained by forming an image on 0 sheets is shown in FIG. 6 (-dotted chain line). During image formation on 10,000 sheets from the initial stage, good images were obtained as in Experimental Example 1. However, after that, the toner charge amount distribution deteriorated to 9 per 12,000 sheets and became broad, resulting in poor images.

(Effects of the Invention) As described above, according to the present invention, a benzidine-based pigment is used as a colorant, and an acrylamide-based polymer containing sulfonic acid and a specific quaternary ammonium are used as a charge control agent for negative charging and a charge control aid. Since it is combined with yellow toner as an agent, the electrical properties of the obtained toner are excellent, that is, the charge amount distribution curve of the charge amount of toner particles is sharp, and the toner in the device has extremely little scattering and has a high concentration. images can be formed. In addition, it is a yellow toner that can provide good images over a long period of time, has excellent reproducibility, and is resistant to impact when used for full color development.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a characteristic curve of the toner charge amount distribution of the present invention, and FIG. 2 is a diagram showing a characteristic curve of the charge amount distribution of a toner using only a charge control agent for negative charging. . FIG. 3 is a diagram showing a characteristic curve of charge amount distribution of a conventional yellow toner, FIG. FIG. 6 is a diagram showing a characteristic curve of the charge amount distribution of a conventional yellow toner, and FIG. 7 is a diagram showing a characteristic curve of the charge amount distribution of a yellow toner, and FIG. 7 is a diagram showing a charge jiII! FIG. 2 is a schematic layout diagram of an I-setting device. Patent applicant: Mita Kogyo Co., Ltd. Representative: Patent attorney: Ikuo Suzuki M7 diagram

Claims (1)

[Scope of Claims] (1) In a negatively charging electrophotographic toner containing a fixing resin, a colorant, and a negative charging charge control agent, the coloring agent is a benzidine pigment, and the negative charging charge control agent is a heavy compound containing an acrylamide monomer of the following formula CH_2=CR'-CO-NS_1S_2 (R' is hydrogen or a lower hydrocarbon, and at least one of S_1 and S_2 is a sulfonic acid-containing hydrocarbon). It is a combination,
In addition to the negative charge control agent, a compound of the following formula which is incompatible with the fixing resin but has dispersibility and has a charge control action of opposite polarity to that of the negative charge control agent is used. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R is at least one long-chain alkyl group or long-chain alkenyl group, and at least two of them are lower alkyl groups or benzyl groups. a lower alkyl group, a benzyl group, a long-chain alkyl group, or a long-chain alkenyl group, and A represents an anion.) A yellow toner characterized in that it contains a charge control auxiliary agent. (2) The charge control agent and the charge control aid are present in a weight ratio of 1:0.05 to 1:1, and in a total amount of 0.5 to 5 parts by weight per 100 parts by weight of the fixing resin. Yellow toner listed. (3) The yellow toner according to claim 1, wherein the molecular weight of the polymer as the charge control agent is in the range of 2,000 to 15,000. (4) The polymer as the charge control agent is a copolymer of the sulfonic acid-containing acrylamide monomer and another addition polymerizable monomer, and the sulfonic acid-containing acrylamide monomer The yellow toner according to claim 1, wherein the yellow toner contains 2% by weight or more based on the total weight.