JPH04195166A - Negatively chargeable electrophotographic toner - Google Patents

Abstract

PURPOSE:To reduce scattering of a toner and to obtain an image high in density by using an acrylamide type polymer having sulfonic acid groups as a negatively chargeable charge controller and a specified quaternary ammonium as an auxiliary charge controller in combination with the negatively chargeable toner. CONSTITUTION:The toner contains as the negatively chargeable charge controller the polymer having an acrylamide type monomer of formula I (R' is a H or a lower hydrocarbon group and each of S1 and S2 is a hydrocarbon group having a sulfonic acid) and as the auxiliary charge controller having a charge controlling action in polarity reverse to the charge controller the quaternary ammonium of formula II (at least one of R is long-chain alkyl or such alkenyl, and at least 2 of them is lower alkyl or benzyl or the like, and A is an anion), thus permitting the obtained toner to prevent toner scattering and to stabilize image density.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a negatively charged electrophotographic toner frequently used in laser beam printers, digital copying systems, etc. in recent years. The present invention relates to a negatively charged electrophotographic toner that does not cause toner scattering, has a bright hue, has excellent image reproducibility, and is capable of forming high-density images.

(Prior Art) In the fields of commercial electrophotographic copying and electrophotographic printing, a method of forming positively charged electrostatic images 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 layer 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 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, in this method, although it is possible to control the average value of the charge amount of the toner as a whole, it is difficult for the device to precisely 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 I'g stimulants having chargeability 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.

Furthermore, JP-A-57-198264 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 in a weight ratio of 5 to 1:1.5.

(While the invention is trying to solve the problem) In conventional negatively charged toners, even if the type and amount of charge control agent added is adjusted so that the average value of the charge amount is a sufficiently satisfactory value. , it is inevitable that the distribution of the amount of charge becomes 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 problems at the beginning of development, as development time progresses, the proportion of uncharged or low-charge toner increases, causing toner scattering, fogging, and image density. Problems such as deterioration will occur.

In the method of combining a positively chargeable dye (charge control agent) with a charge control agent for negative charge as 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. Even though this method has the advantage of sharpening the toner charge amount distribution and suppressing the generation of highly charged toner and lowly charged toner to a negligible level, this method is still not fully satisfactory. It wasn't something to be gained.

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

(Means for Solving the Problems) According to the present invention, in a negatively charged electrophotographic toner containing a fixing resin, a colorant, and a negatively charged charge control agent,
The negative charge control agent contains an acrylamide monomer of the following formula % (R' is hydrogen or a lower hydrocarbon, and at least one of S and S2 is a sulfonic acid-containing hydrocarbon). It is a polymer consisting of
In addition to the negative charge control agent, R of the following formula is incompatible with the fixing resin but has dispersibility 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, and at least two of them are a lower alkyl group or a benzyl group. Below, a lower alkyl group, a benzyl group, a long-chain alkyl group, or a long-chain alkenyl group, and A represents an anion.) Provided is an electrophotographic toner for negative charging characterized by containing a charge control aid. be done.

In the electrophotographic toner for negative charging, the charge control agent and the charge control aid are present in a weight ratio of 1:0.05 to 1:1,
Further, it can be characterized in that it is present in a total amount of 0.5 to 5 parts by weight per 100 parts by weight of the fixing resin.

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 electrophotographic toner for negative charging of the present invention contains a fixing resin 1 colorant, a charge control agent for negative charging, and a charge control auxiliary agent as essential components. By using a polymer containing a specific acrylamide monomer containing sulfonic acid as a charge control agent, and by combining this with a specific j14th class ammonium charge control, extremely good electrical properties can be achieved. We have discovered an excellent toner.

Charge control for negative charging is CH2=CR'-CO-NS,
It is important that the polymer is a polymer containing an acrylamide monomer of 52 (R' is hydrogen or a lower hydrocarbon, and S and S2 are ψ at least one of them is a sulfonic acid-containing hydrocarbon). Such a charge 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 aid has the following formula: R-N4-R-A- (wherein R is at least one long-chain alkyl group or long-chain alkenyl group, and at least 21 of them are long-chain alkyl groups or long-chain alkenyl groups;
is a lower alkyl group, a benzyl group, a long-chain alkyl group, or a long-chain alkenyl group, and A represents an anion), and this Such charge IIIF coagents are 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 between highly charged toner and lowly charged toner disappears.6 Highly charged toner has poor transferability to the photoreceptor, and lowly charged toner tends to cause toner scattering. As a result, the electrophotographic toner for negative charging of the present invention can effectively suppress the occurrence of such problems.

FIG. 2 of the accompanying drawings shows a time distribution diagram of the charge amount of toner A using only a conventional charge control agent for negative charging (Experiment Example 3);
FIG. 3 shows a distribution characteristic diagram of the charge amount of toner B containing a negatively charging charge control agent and a positively charging dye (see Experimental Example 4), and I! FIG. 1 is a diagram (see Experimental Example 1) showing the charge amount distribution characteristic of the electrophotographic toner C for negative charging according to the present invention. In addition, Table 1 below shows these toners A,
For B and C, the characteristic values of the charge amount distribution, which will be described later, are summarized.

In toner A using a conventional negative charge control agent, as shown in FIG. 2, there are many highly charged toners in the a region and
It also contains a considerable proportion of oppositely charged toner and O-charged toner. Furthermore, in Toner B of the prior art in which a positively chargeable dye is used as 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 that of toner A, the highly charged toner in the a region is decreased but still exists, and the ratio of the oppositely charged toner and the O charged toner in the d region is increased.

In contrast, the toner of the present invention is a combination of a negative charge control agent of a polymer containing CH2=CR'-CO-NS,S, and a positive charge control substance incompatible with a fixing resin as an auxiliary agent. As shown in Fig. 1, in C, the amount of toner in the proper charge range C increases and the width of the charge distribution becomes extremely narrow, and the highly charged toner in the A castle and the oppositely charged toner in the D range and the O It is understood that charged toner can be reduced (here eliminated).

Table 1 shows how toners A, B, and C were used, and a laser beam printer LPX-1 (manufactured by Sanda Kogyo Co., Ltd., trade name) modified AL (improved to a reversal development method) was used to produce 100%
The image density (ID), image fog density (FD) and toner scattering around the developing device were evaluated when 0 sheets were continuously copied.

From Figures 1 to 3 of Table 1 and 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 capri, and toner scattering.

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 It is presumed that the sulfonic acid group and the 114th class ammonium as a charge control aid interact 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 A developer consisting of and a carrier in a developing device! When R# is applied, the charge rises slowly. On the other hand, in the toner of the present invention in which a sulfonic acid-containing acrylamide charge control agent and the above-mentioned auxiliary agent are combined, the charge rises when the developer is started to be stirred and charged.
It also has the advantage of being extremely fast.

(Preferred embodiment of the invention) Hereinafter, embodiments according to the present invention will be described.

4 traps! ! Empress 1 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 114th-grade ammonium salts include the formula 1R-N''-R-A- where at least one of R is a long-chain alkyl group or a long-chain alkenyl group, and at least two of them are is a lower alkyl group or a benzyl group,
It is a lower alkyl group, benzyl group, long-chain alkyl group or long-chain alkenyl group, and A 1 represents an anion, particularly preferably an oxyacid anion.

Compounds represented by can be mentioned. Examples of oxyacid anions include phosphorus oxyacids such as orthophosphoric acid and pyrophosphoric acid, molybdic acid, and tungstic acid.

Examples include anions such as 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.

Charge 11 charge agent 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 S and S2 are at least one of sulfonic acid-containing hydrocarbons. ) 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 aliphatic or aromatic, and is particularly preferably a lower hydrocarbon having 1 to 6 carbon atoms. in particular.

3-acrylamido-3-methylbutylsulfonic acid, 2
-acrylamido-2-methylbutylsulfonic acid, 2-
Acrylamido-2-methylpropanesulfonic acid, 2-
Examples include acrylamide-methylsulfonic 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 (sulfonic acid-containing acrylamide monomer). Acrylamide monomer is 2
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 these paper combinations are preferably present in a total amount of 1 to 5 parts by weight, especially 2 to 4 parts by weight per 1100 parts by weight of fixing material.

As the fixing resin, a known fixing resin that is not compatible with the charge control aid but exhibits dispersibility is used. These fixing resins.

Since the toner is negatively charged, it is desirable that the toner has a tendency to be negatively charged, and for example, a styrene resin, an acrylic resin, or a styrene-acrylic copolymer resin is generally used.

As for the styrene monomer used in these resins, 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, the acrylic sJ1 is a monomer represented by formula 1, where R3 is a hydrogen atom or a lower alkyl group, and R4 is a hydrogen atom or a substituted or unsubstituted alkyl group having up to 18 carbon atoms. 1 For example, ethyl acrylate.

Methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-
These include ethylhexyl 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. In particular, a range of 60:40 to 85:15 is preferable. Further, the resin used generally preferably has an acid value of O to 25, and also preferably has a glass transition temperature (T[) of 50 to 75° C. from the viewpoint of fixing properties.

As the coloring agent contained in the resin, the following inorganic or organic pigments and dyes can be used alone or in combination of two or more. Carbon blanks such as furnace black and channel black; iron black such as triiron tetroxide; titanium dioxide such as rutile type or anatase type; phthalocyanine green; cadmium yellow; molybdenum orange;
Pyrazolone red: Fast Violet B, etc. can be mentioned.

Toner The particle size of the toner particles is preferably in the range of 5 to 15 μm in terms of volume-based median diameter, especially 7 to 12 μm, as measured by a coulter counter, and the particle size is determined by the melt mixing/pulverization method. It may be an amorphous material produced by a method or a spherical material 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.

Conventionally, ferrite has been used, for example, iron zinc oxide (ZnFe2
0. ), iron yttoram oxide (Y3Fe50+2) - iron cadmium oxide (CdFe204), iron gadolinium oxide (Gd3Fe20.2), iron copper oxide (CuFe204)
, iron oxide complex (PbFe+20+J, iron nickel oxide (N
iFe204), neodymium iron oxide (NdFe03)
, barium iron oxide (BaFe+20+e), magnesium iron oxide (MnFe204).

Iron manganese oxide (MnFe204), iron lanthanum oxide (
Sintered ferrite particles having a composition consisting of one or more types such as Lapse, Z.
Soft ferrites, such as copper-zinc-magnesium ferrites, containing at least one, preferably two or more, of metal components selected from the group consisting of n, Hl, Mn and Ni are used. , is also suitably used in the present 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 em
u/g, particularly preferably in the range of 45 to 70 emu/g. The magnetic carrier is preferably a ferrite carrier that satisfies the above conditions, particularly a spherical ferrite carrier, and its particle size is preferably in the range of 20 to 140 μm, particularly 50 to 100 μm.

The specific gravity of the mixture 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 5:95.
It is desirable that it be within the range of . In addition, the electrical resistivity of the developer as a whole is 5 x 10" to 5 x 10".
Ω"el, preferably 5x100 to 5x10"Ω・
It is generally desirable that it be in the cm range.

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.

Electrification Amount To explain the charge tS constant 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 5 to blow compressed air onto the developer held on the magnet 4, leaving behind the carrier magnetically attracted to the magnet 4, and blowing only the lightweight toner upward and scattering it. let

A funnel 6 supported by a partition plate 7 is provided between the separating section 2 and the measuring section 3. A receiving opening 6d at the upper end of the funnel 6 protrudes above the partition plate 7, and a recessed portion 6a at the lower end passes through the filter 8 and faces the measuring section 3 side.

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

10 is a filter.

The suction device 11 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 charge amount measuring 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 lo.

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 according to the amount of charge and gravity ■ 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 resin: 100 parts by weight of styrene-acrylic copolymer.

Colorant: 5 parts by weight of carbon black, charge control agent for negative charging: copolymer of styrene and 2-acrylamido-2-methylpropanesulfonic acid (composition ratio = 20:1, weight average molecular weight (w): 8000 ) 2 parts by weight, charge control aid: 0.5 quaternary ammonium salt of the following formula
More than one part of the mixture was melted and kneaded using a twin-screw pusher, and the mixed material 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 used as a toner with a concentration of 4.
Mix and stir at 5% to make a developer, and prepare I! 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) (Photoreceptor surface potential knee 7
00V, development bias potential, -500V) J: was applied, 1000 ia images were formed, and image characteristics were observed. As shown in Table 1, there was a decrease in image density, image fog,
■・It was a good image with no toner scattering at all. Furthermore, 50
When continuous image formation was performed on 10,000 sheets and fluctuations in the toner charge amount distribution were tracked, as shown in FIG. 4, the toner charge amount distribution did not change and remained good even after 10,000 sheets were printed.

(Example 2) Styrene and 2-acrylamide-2- as charge control agents
Copolymer with methylbutylsulfonic acid (composition ratio = 20
: 1, weight average molecular weight (Mv): 10000) to 2
A toner was prepared in the same manner as in Experimental Example 1, except that the parts by weight and the charge control aid were changed to 0.51 parts of a quaternary ammonium salt of the following formula.

Hereinafter, a developer was obtained in the same manner as in Example 1, and fluctuations in toner charge amount distribution were tracked during continuous image formation on 50,000 sheets. As a result, similar to Experimental Example 1, a good image was obtained,
The force was such that the toner was scattered inside the device. The toner charge amount distribution was similarly measured before printing and after printing 5,000 sheets, and it was found to be as sharp as in Experimental Example 1.

(Experimental Example 3) The same procedure as in Experimental Example 1 was conducted except that the charge control aid was not used. FIG. 2 shows the charge amount distribution of the obtained toner. Observation of image characteristics after continuous image formation on 5,000 sheets revealed that the image density was unstable, and image fogging and toner scattering also occurred.

(Experiment Example 4) Instead of the charge Ig auxiliary agent, C which is compatible with the fixing resin number
, 1.5olvent (Solhento) , Ye
The same procedure as in Experimental Example 1 was conducted except that 2 parts by weight of LOW (yellow) 56 was used. The charge amount distribution of the obtained toner is shown in Figures 1 and 3. Further, when observing the image characteristics after continuous image formation on 5000 sheets, the image density was unstable and the image density occasionally dropped. Furthermore, one image fog and toner scattering also occurred.

(Experimental Example 5) 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, as a result of observing the image characteristics after continuous image formation on 5,000 sheets, good images were obtained in the initial stage and there was no toner scattering within the device, but at the end of the process (from 4,500 sheets onwards), although the degree of scattering was small, Fog and fluctuations in image density were observed. Figure 5 shows the charge amount distribution before and after the end of life printing. From Figure 6, it is clear that the sharp charge amount distribution at the initial stage becomes broader with the end of life printing, resulting in defective charged toner. I understand.

(Effects of the Invention) As described above, according to the present invention, a sulfonic acid-containing acrylamide polymer and a specific quaternary ammonium are used as a charge control agent for negative charge and a charge control auxiliary agent to form an electrophotographic toner for negative charge. As a result, the electrical properties of the obtained toner are excellent, that is, the charge distribution curve of the charge amount of the toner particles is sharp, and the toner in the device has extremely little scattering, and moreover, it forms a high-density image. I can do it.

Moreover, good images can be provided for a long period of time.

[Brief explanation of the drawing]

I! 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 the charge amount distribution of a toner using a negatively charging charge control agent and a positively charging compatible dye. FIG. 4 is a characteristic curve diagram showing the variation in the charge amount distribution of the toner of the present invention, and FIG. 315 is a characteristic curve of the charge amount distribution of the toner using a metal-containing monoazo dye as a charge control agent for negative charging. FIG. 6 is a schematic layout diagram of a charge amount measuring device used to measure the charge amount distribution of toner. Patent applicant Sanda Kogyo Co., Ltd. Figure 6

Claims (4)

[Claims] (1) In a negatively charging electrophotographic toner containing a fixing resin, a colorant, and a negative charge control agent, the negative charge control agent has the following formula CH_2=CR'-CO-NS_1S_2 (R' is hydrogen or a lower hydrocarbon; at least one of S_1 and S_2 is a sulfonic acid-containing hydrocarbon);
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.) An electrophotographic toner for negative charging characterized in that it contains a charge control aid. . (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. The electrophotographic toner for negative charging described above. (3) The molecular weight of the polymer as the charge control agent is 200.
2. The electrophotographic toner for negative charging according to claim 1, wherein the electrophotographic toner has a molecular weight ranging from 0 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 2. The electrophotographic toner for negative charging according to claim 1, wherein the electrophotographic toner contains 2% by weight or more based on the total weight of the toner.