JP2002351147A - Charge control agent and electrophotographic negative charge toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrophotographic negative charge toners which lessen the change in the electrostatic charge quantity by desorption of a charge control agent, lessen the change in toner characteristics, more particularly electrostatic charge quantity at and under high temperature and high humidity or low temperature and low humidity and make bright color toners obtainable and the charge control agent which obtains such toners. SOLUTION: The charge control agent consisting of a copolymer of 1 to 30 wt.% acrylamide methylpropane sulfonate and 99 to 70 wt.% other vinyl monomer copolymerizable therewith or a copolymer of 1 to 30 wt.% acrylamide methylpropane sulfonic acid and 99 to 70 wt.% other vinyl monomer copolymerizable therewith and the electrophotographic negative charge toners into which the charge control agent described above is incorporated at 0.1 to 10 pts.wt. per 100 pts.wt. binder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negatively charged toner for electrophotography used when a latent electrostatic image is converted into a visible image in dry electrophotography, and a charge control agent mainly used for the toner.

[0002]

2. Description of the Related Art In dry electrophotography, toner particles used to convert a latent electrostatic image into a visible image generally include a binder, a coloring agent, a charge controlling agent, a magnetic powder if necessary, and other materials. After the additives are pre-mixed, they are melt-kneaded, pulverized, and then classified to have a desired particle size.

When these toner particles are used as a two-component developer, the toner particles are mixed and stirred with a magnetic powder to cause friction between the toner particles, thereby accumulating electric charge on the surface of the toner particles to form an electrostatic charge. The latent image is provided for visualization (development). When these toner particles are used as a one-component developer, electric charges are accumulated on the surface of the toner particles due to friction between the toner particles and a sleeve or the like, so that the electrostatic charge latent image can be visualized (developed). Provided.

Here, the charge accumulated on the surface of the toner particles due to frictional charging needs to be either positive or negative depending on the type of photoconductive photoreceptor used to form an electrostatic latent image. . In addition, it is generally necessary to mix and disperse a charge control agent or a conductive substance in a binder since it is necessary to have a charge amount sufficient to visualize the latent electrostatic image more accurately.

Conventionally, as a charge control agent for imparting a negative charge to toner particles, metal-containing complex dyes and the like as described in JP-B-45-26478 and the like have been generally used. However, since the metal-containing complex salt dye has a complicated structure and unstable properties, it is easily decomposed or deteriorated by thermal and mechanical influences in the melt-kneading and pulverizing steps in the production of toner, and charge control. However, there was a disadvantage that the property was reduced. Therefore, there is a problem that the toner characteristics of the obtained toner are significantly reduced.

[0006] Further, the metal-containing complex salt dye is not well compatible with the thermoplastic resin as a binder and, like the colorant, exists only in a particle-dispersed state in the binder. For this reason, in the pulverizing step in the production of toner or in flow friction in a copying machine when electric charges are accumulated on the surface of toner particles, the charge control agent present on the surface layer of the toner particles falls off and changes the charge amount. In addition, there is a disadvantage that the charge amount of each toner particle varies. Therefore, there is a problem that it is difficult to stably maintain the charged state of the toner for a long period of time. In addition, metal complex dyes
In general, since they are colored and have poor transparency, there has also been a problem that a color copy of a clear color tone cannot be obtained when an arbitrary coloring is performed in correspondence with color copying.

[0007] In order to solve the problems of the metal-containing complex dyes and the like as the negative charge controlling agent, the present applicant has prepared a polymerizable compound having negative charge controllability and a polymerizable vinyl monomer copolymerizable therewith. Invented a negatively charged toner for electrophotography in which a copolymer was copolymerized and the obtained copolymer was contained in a binder as a negative charge control agent, and a patent application was previously filed (Japanese Patent Application Laid-Open No. 63-184).
762, JP-A-3-56974).

The above copolymer-based negative charge control agent is excellent in compatibility with the synthetic resin as a binder, and therefore, the charge amount due to detachment of the charge control agent, such as in the case of a metal-containing complex dye, etc. There was no problem such as a change in charge or a variation in charge amount. In addition, it has the advantage that it can be colored arbitrarily and vividly in accordance with color copying. However, since acrylamidomethylpropanesulfonic acid is used as a polymerizable compound having negative charge controllability, the toner characteristics at high temperature and high humidity, especially the attenuation of the charge amount is relatively large, and a clear image can be formed stably for a long period of time. There was a problem that it was difficult to make it.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to achieve good compatibility with synthetic resins such as a binder, stable negative charging characteristics, and environmental changes (high temperature, high humidity, low temperature, low humidity). There is no change in the charge amount due to the change in the charge amount, and there is no change in the charge amount due to the release of the charge control agent. An object of the present invention is to provide a negatively charged toner for electrophotography which can be obtained.

[0010]

That is, the charge control agent of the present invention comprises 1 to 30% by weight of acrylamidomethylpropanesulfonate and 99 to 70% by weight of another vinyl monomer copolymerizable therewith. A copolymer or 1 to 30% by weight of acrylamidomethylpropanesulfonic acid;
It is characterized by comprising a copolymer obtained by treating a copolymer with 99-70% by weight of another copolymerizable vinyl monomer with an alkali agent. Further, the negatively charged toner for electrophotography of the present invention contains a binder and the charge control agent of the present invention, and the charge control agent is used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the binder. It is characterized by being contained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The charge control agent of the present invention is largely characterized by comprising a copolymer having an acrylamidomethylpropanesulfonate unit and another vinyl monomer unit. .

Such a copolymer is obtained by copolymerizing 1 to 30% by weight of acrylamidomethylpropanesulfonate with 99 to 70% by weight of another vinyl monomer copolymerizable therewith. It is. Further, such a copolymer is obtained by copolymerizing 1 to 30% by weight of acrylamidomethylpropanesulfonic acid with 99 to 70% by weight of another vinyl monomer copolymerizable therewith, and treating this with an alkali agent. To convert the hydrogen of the sulfonic acid group of the acrylamidomethylpropanesulfonic acid unit into an alkali metal,
It is obtained by substituting with an alkaline earth metal, ammonium or the like.

In the copolymerization of acrylamidomethylpropanesulfonic acid or a salt thereof with another vinyl monomer copolymerizable therewith, if the proportion of acrylamidomethylpropanesulfonic acid or a salt thereof is less than 1% by weight, it is obtained. It becomes difficult to accumulate a sufficient amount of charge in the toner, and the toner scatters so much that it cannot be used.
On the other hand, when the ratio of acrylamidomethylpropanesulfonic acid or its salt exceeds 30% by weight, the obtained toner has a low electric resistance value, deteriorates the stability over time of the change in charge amount, and binds to the charge control agent. The compatibility with the agent also deteriorates, the transparency is impaired, and it becomes difficult to obtain a clear color tone. In preferred copolymerization of acrylamidomethylpropanesulfonic acid or a salt thereof and another vinyl monomer copolymerizable therewith, preferably, acrylamidomethylpropanesulfonic acid or a salt thereof is 2 to 20.
% And the other copolymerizable vinyl monomer is 98 to 80% by weight.

The acrylamidomethylpropanesulfonate includes those represented by the following general formulas (I) and (II).

[0015]

Embedded image

In the formula, M is an alkali metal or NR ¹ R ² R
³ is a H. Further, R ¹ , R ² and R ³ are not particularly limited, such as hydrogen, a substituted or unsubstituted hydrocarbon group. The alkali metal is preferably sodium, potassium, NR ¹
R ² R ³ H is preferably NH ₄ .

[0017]

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Wherein M is an alkaline earth metal, n is 1 or 2, and m is 2-n. The alkaline earth metal is preferably calcium or magnesium.

Specific examples of the acrylamidomethylpropanesulfonate represented by the general formula (I) include sodium acrylamidomethylpropanesulfonate, ammonium acrylamidomethylpropanesulfonate, and potassium acrylamidomethylpropanesulfonate. Specific examples of the acrylamidomethylpropanesulfonate represented by the general formula (II) include calcium acrylamidomethylpropanesulfonate and magnesium acrylamidomethylpropanesulfonate. These acrylamidomethylpropanesulfonic acid salts can be used alone or in combination of two or more.

Among the acrylamidomethylpropanesulfonates exemplified above, acrylamidomethylpropanesulfonate is preferred because it is easy to copolymerize and a copolymer having a softness preferable as a component of an electrophotographic toner is easily obtained. It is preferable to use at least one selected from sodium propanesulfonate, ammonium acrylamidomethylpropanesulfonate, and potassium acrylamidomethylpropanesulfonate.

The other vinyl monomer which can be used as a co-component with the above-mentioned acrylamidomethylpropanesulfonic acid or a salt thereof is not particularly limited and may be any one having a polymerizable unsaturated bond. Can also be used. Specific examples include styrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene,
α-methylstyrene, vinyltoluene, (meth) acrylic acid, maleic acid, itaconic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) ) -2-Ethylhexyl acrylate, amyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, acrylamide, vinyl chloride, vinyl acetate And the like. Among these vinyl monomers, it is preferable to use at least one selected from styrene and alkyl (meth) acrylate. As the alkyl (meth) acrylate, an alkyl (meth) acrylate having an alkyl group having 1 to 18 carbon atoms is preferably used.

In particular, in the present invention, at least one of sodium acrylamidomethylpropanesulfonate, ammonium acrylamidomethylpropanesulfonate and potassium acrylamidomethylpropanesulfonate is selected as the acrylamidomethylpropanesulfonate, A copolymer obtained by copolymerizing at least one selected from styrene and an alkyl (meth) acrylate as a vinyl monomer is transparent and well compatible in a binder, and is subjected to high temperature and high humidity conditions. Therefore, it is preferable to use a copolymer having such a monomer composition as a charge control agent because the toner characteristics can be stabilized even in a harsh environment as described above.

The method for producing a copolymer of acrylamidomethylpropanesulfonic acid or a salt thereof and another vinyl monomer copolymerizable therewith is not particularly limited, and a known radical polymerization method is employed. be able to. Specifically, there are a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, a dispersion polymerization method, and the like.In particular, a solution weight in which a polymerization reaction is carried out in an organic solvent in the presence of an appropriate polymerization initiator. Legal is suitable. There is no particular limitation on the polymerization initiator at that time, and known initiators usually used in radical polymerization reactions, for example, benzoyl peroxide, te
rt-butyl perbenzoate, dicyclohexyl peroxide, dicumyl peroxide, azobisisobutyronitrile, azobismethylbutyronitrile, azobisdimethylvaleronitrile and the like can be used.

The copolymer of acrylamidomethylpropanesulfonic acid and another vinyl monomer copolymerizable therewith is treated with an alkali agent to convert the hydrogen of the sulfonic acid group of the acrylamidomethylpropanesulfonic acid unit. It is substituted by an alkali metal, an alkaline earth metal, ammonium or the like, and serves as a charge control agent in the present invention. As the alkaline agent, for example, sodium hydroxide (NaO
H), sodium nitrate (NaNO _3), potassium hydroxide (KOH), calcium hydroxide (Ca (OH) _2), calcium nitrate _{(Ca (NO 3) 2 ·} 4H 2 O), magnesium hydroxide (Mg (OH ₂ ), ammonia (NH ₃ )
And the like.

There are no particular restrictions on the molecular weight, glass transition temperature, etc., of the copolymer as the charge control agent, but it can be mixed in a transparent state with the binder and is good for the final toner. Weight-average molecular weight (hereinafter, referred to as Mw) of 5,000 to 1,000,000 in that the storage stability and charging characteristics can be maintained over a long period of time.
0, glass transition temperature (hereinafter referred to as Tg) 30 to 100
The temperature is preferably in the range of ° C.

The negatively charged toner for electrophotography according to the present invention (hereinafter referred to as “the toner”)
The toner is abbreviated as a toner of the present invention), which is characterized by using a copolymer comprising an acrylamidomethylpropanesulfonate unit and another vinyl monomer unit as a charge control agent.

As the binder that can be used in the toner of the present invention, any of various synthetic resins conventionally used as binders for electrophotographic toners can be used.
As a specific example, at least one diol component selected from the group consisting of a homopolymer of polystyrene or (meth) acrylate or a copolymer resin thereof, a bisphenol-type diol and a glycol, and phthalic acid, isophthalic acid, Examples include polyester resins synthesized from dicarboxylic acids such as terephthalic acid or trimellitic acid.

In the toner of the present invention, the content of the charge control agent is 0.1 to 10 parts by weight based on 100 parts by weight of the binder.
Parts by weight. If the content of the charge control agent is less than 0.1 part by weight, the rise of toner charging becomes poor, toner scattering is large, and defects such as toner dripping occur. The hygroscopicity is increased, and the change over time in the charge amount is increased.

The toner of the present invention includes various known and commonly used organic pigments and inorganic pigments to obtain toner particles having a desired color tone.
Colorants such as extenders and dyes may be included.
Specific examples of the coloring agent that can be used include black pigments (carbon black, acetylene black, run black, etc.),
Yellow pigments (eg, yellow lead, yellow iron oxide, mineral fast yellow, navel yellow, Hanser yellow, benzidine yellow, permanent yellow, etc.), red pigments (eg, red bengala, cadmium red, permanent red, lake red, brilliant carmine), blue pigments (Navy blue,
Cobalt blue, phthalocyanine blue, fast sky blue, induslen blue, etc.), green pigments (chrome green, malachite green lake, etc.), white pigments (zinc white, titanium oxide, etc.), extender pigments (barium carbonate,
Pigments such as clay, silica, talc, and alumina white), and dyes such as benzidine yellow, hansa yellow, and chromophtallier. These colorants can be used alone or in combination of two or more.

The toner of the present invention can be manufactured by various known methods. As an example, a predetermined amount of the binder, the charge control agent, the colorant, and, if necessary, a conventional amount of various other toner additives are mixed, melt-kneaded, and pulverized through respective steps of 5 to 5. A method of producing by classifying so as to have an average particle diameter of 20 μm, or a method in which raw materials other than the main resin (charge control agent, colorant, etc.) are dispersed in a monomer constituting the main resin, and formed during polymerization of the main resin. Polymerized toner method in which these raw materials are incorporated into toner particles, and a method in which toner constituent materials are dissolved or dispersed in an appropriate organic solvent and granulated by using a device such as spray drying. .

The toner of the present invention can be used as a two-component developer, for example, by blending it with an appropriate carrier.
As the carrier, glass beads or steel balls coated with resin are used when the cascade developing method is performed, and ferrite, fine iron powder, or a so-called binder type carrier is used when the magnetic brush developing method is performed. Alternatively, the toner of the present invention may be manufactured as an insulating magnetic toner, and the magnetic brush developing method may be performed using the toner as a one-component developer. Further, the toner may be used as a toner when an impression development method is performed.

The present invention has been described above with respect to a negatively charged toner for electrophotography. However, since the charge control agent of the present invention is a copolymer having electric characteristics which are good in itself, this characteristic can be applied. It may be used for various applications, for example, as a surface coating agent for an electrophotographic carrier, a resin binder for a powder coating, and the like. The copolymer in this case may be used alone, or may be used as a blend with another appropriate resin.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. [Example 1] (Production of charge control agent) Stirrer, condenser, thermometer,
300 g of methanol in a 2 L flask equipped with a nitrogen inlet tube
And 100 g of methyl ethyl ketone, and 5% by weight of acrylamidomethylpropanesulfonic acid, 85% by weight of styrene, and 2-ethylhexyl acrylate 10%.
600 g of a monomer mixture consisting of 100% by weight and 12 g of azobisisobutyronitrile were charged, and solution polymerization was carried out at 70 ° C. for 10 hours while introducing these while stirring.
After the completion of the solution polymerization, 60 g of NaOH (10% by weight methanol solution) was added to the solution, followed by stirring at 70 ° C. for 1 hour. After the treatment with the alkali agent, the solution was transferred to a reduced pressure heating furnace, and methanol and methyl ethyl ketone were removed from the solvent to obtain a copolymer (weight average molecular weight = 50,000, Tg = 70 ° C.). This copolymer was used as a charge control agent.

(Production of Toner) 100 parts of styrene / acrylic copolymer resin, 5 parts of charge control agent obtained above, 5 parts of carbon black (MA # 100, manufactured by Mitsubishi Chemical Corporation), and Viscol 550P (Sanyo Chemical Industries, Ltd.) 3 parts)
Melt and knead with Labo Plast Mill (manufactured by Toyo Seiki Seisaku-Sho, Ltd.), finely pulverize with a jet mill, and classify to average particle size of 10μ
m of toner were produced.

(Evaluation of Toner) The toner obtained above was evaluated by the following method, and the results are shown in Table 1. (1) High-temperature and high-humidity characteristics A toner and a carrier (reduced iron powder) are mixed at a ratio of 3: 100, and the mixture is mixed under a high-temperature and high-humidity atmosphere of 35 ° C. and 85% RH.
For 3 minutes, and the charge amount (-μC / g) was measured using a pro-off powder charge amount measurement device manufactured by Toshiba Chemical Corporation.
The charge amount at this time was defined as CH. Similarly, 20 ° C / 65%
The charge amount (−μC / g) was measured under the condition of RH, and the charge amount at this time was defined as CN. Using these results, the charge reduction rate was determined from the following equation. Charge reduction rate (%) = 100− (CH / CN) × 100

(2) Low-temperature and low-humidity characteristics The toner and the carrier (reduced iron powder) are mixed at a ratio of 3: 100, and are mixed under a low-temperature and low-humidity atmosphere of 10 ° C. and 40% RH.
For 3 minutes, and the charge amount (-μC / g) was measured using a pro-off powder charge amount measurement device manufactured by Toshiba Chemical Corporation.
The charge amount at this time was designated as CL. Similarly, 20 ° C / 65%
The charge amount (−μC / g) was measured under the condition of RH, and the charge amount at this time was defined as CN. Using these results, the charging rise rate was determined from the following equation. Charge rise rate (%) = (CL / CN) × 100-100

[Example 2] (Production of charge control agent) Stirrer, condenser, thermometer,
300 g of methanol in a 2 L flask equipped with a nitrogen inlet tube
And 100 g of methyl ethyl ketone, and 20% by weight of acrylamidomethylpropanesulfonic acid, 70% by weight of styrene, 2-ethylhexyl acrylate 1
600 g of a monomer mixture consisting of 0% by weight and 12 g of azobisisobutyronitrile were charged, and solution polymerization was carried out at 70 ° C. for 10 hours while introducing nitrogen while stirring them. After completion of the solution polymerization, 240 g of NaOH (10% by weight methanol solution) was added to the solution, and the mixture was stirred at 70 ° C. for 1 hour. After the treatment with the alkali agent, the solution was transferred to a reduced pressure heating furnace, and methanol and methyl ethyl ketone were removed from the solvent to obtain a copolymer (weight average molecular weight = 50,000, Tg = 72).
° C). This copolymer was used as a charge control agent.

(Production and Evaluation of Toner) A toner was produced in the same manner as in Example 1 except that only the charge control agent was changed, and the evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Example 3 (Production of Charge Control Agent) Stirrer, condenser, thermometer,
300 g of methanol in a 2 L flask equipped with a nitrogen inlet tube
And 100 g of methyl ethyl ketone, 5% by weight of acrylamidomethylpropanesulfonic acid, 85% by weight of styrene, and 10% by weight of 2-ethylhexyl acrylate.
600 g of a monomer mixture consisting of 100% by weight, 12 g of azobisisobutyronitrile and 120 g of NaOH (10% by weight methanol solution) were charged, and solution polymerization was carried out at 70 ° C. for 10 hours while introducing nitrogen while stirring them. After the solution polymerization was completed, the solution was transferred to a reduced pressure heating furnace, and methanol and
The solvent was removed from methyl ethyl ketone to obtain a copolymer (weight average molecular weight = 50,000, Tg = 70 ° C.). This copolymer was used as a charge control agent.

(Production and Evaluation of Toner) A toner was produced in the same manner as in Example 1 except that only the charge control agent was changed, and this was evaluated in the same manner as in Example 1. Table 1 shows the results.

[Example 4] (Production of charge control agent) Stirrer, condenser, thermometer,
300 g of methanol in a 2 L flask equipped with a nitrogen inlet tube
And 100 g of methyl ethyl ketone, 5% by weight of acrylamidomethylpropanesulfonic acid, 85% by weight of styrene, and 10% by weight of 2-ethylhexyl acrylate.
600 g of a monomer mixture consisting of 100% by weight and 12 g of azobisisobutyronitrile were charged, and solution polymerization was carried out at 70 ° C. for 10 hours while introducing these while stirring.
After completion of the solution polymerization, 90 g of KOH (10% by weight methanol solution) was added to the solution, followed by stirring at 70 ° C. for 1 hour. After the treatment with the alkali agent, the solution was transferred to a reduced pressure heating furnace, and methanol and methyl ethyl ketone were removed from the solvent to obtain a copolymer (weight average molecular weight = 50000, Tg = 70 ° C.). This copolymer was used as a charge control agent.

(Production and Evaluation of Toner) A toner was manufactured in the same manner as in Example 1 except that only the charge control agent was changed, and the evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Example 5 (Production of Charge Control Agent) Stirrer, condenser, thermometer,
300 g of methanol in a 2 L flask equipped with a nitrogen inlet tube
And 100 g of methyl ethyl ketone, 5% by weight of acrylamidomethylpropanesulfonic acid, 85% by weight of styrene, and 10% by weight of 2-ethylhexyl acrylate.
600 g of a monomer mixture consisting of 100% by weight and 12 g of azobisisobutyronitrile were charged, and solution polymerization was carried out at 70 ° C. for 10 hours while introducing these while stirring.
After the completion of the solution polymerization, NH ₃ (25% by weight aqueous solution) 1 is added to the solution.
0 g was added and the mixture was stirred at 70 ° C. for 1 hour. After the treatment with the alkali agent, the solution was transferred to a reduced pressure heating furnace, and methanol and methyl ethyl ketone were removed from the solvent to obtain a copolymer (weight average molecular weight = 50000, Tg = 68 ° C.). This copolymer was used as a charge control agent.

(Production and Evaluation of Toner) A toner was produced in the same manner as in Example 1 except that only the charge control agent was changed, and evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Example 6 (Production of charge control agent) Stirrer, condenser, thermometer,
900 g of pure water, disodium dodecyl diphenyl ether disulfonate (47% by weight aqueous solution) as an emulsifier, and 0.6 g of potassium peroxodisulfate as an initiator were charged into a 5 L flask equipped with a nitrogen inlet tube, and 5% by weight of acrylamidomethylpropanesulfonic acid was further added. , 600 g of a monomer mixture consisting of 85% by weight of styrene and 10% by weight of 2-ethylhexyl acrylate, and emulsion polymerization was carried out at 80 ° C. for 4 hours under nitrogen while stirring these. In order to reduce the residual monomer, 0.6 g of potassium peroxodisulfate was added, and emulsion polymerization was further performed at 80 ° C. for 1 hour. After the emulsion polymerization, at 70 ° C, C
a (NO ₃ ) ₂ aqueous solution (10% by weight) 1500 g was added,
Reacted. The precipitated polymer was dehydrated and dried to obtain a copolymer (weight average molecular weight = 800000, Tg = 8).
8 ° C). This copolymer was used as a charge control agent.

(Production and Evaluation of Toner) A toner was produced in the same manner as in Example 1 except that only the charge control agent was changed, and this was evaluated in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 (Production of Charge Control Agent) Stirrer, condenser, thermometer,
300 g of methanol in a 2 L flask equipped with a nitrogen inlet tube
And 100 g of methyl ethyl ketone, 5% by weight of acrylamidomethylpropanesulfonic acid, 85% by weight of styrene, and 10% by weight of 2-ethylhexyl acrylate.
600 g of a monomer mixture consisting of 100% by weight and 12 g of azobisisobutyronitrile were charged, and solution polymerization was carried out at 70 ° C. for 10 hours while introducing these while stirring.
After the completion of the solution polymerization, the solution was transferred to a reduced pressure heating furnace, and methanol and methyl ethyl ketone were removed from the solvent to obtain a copolymer (weight average molecular weight = 50000, Tg = 67 ° C.). This copolymer was used as a charge control agent.

(Production and Evaluation of Toner) A toner was manufactured in the same manner as in Example 1 except that only the charge control agent was changed, and the evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 (Production of Charge Control Agent) Stirrer, condenser, thermometer,
300 g of methanol in a 2 L flask equipped with a nitrogen inlet tube
And 100 g of methyl ethyl ketone, and 0.5% by weight of acrylamidomethylpropanesulfonic acid,
600 g of a monomer mixture composed of 89.5% by weight of styrene and 10% by weight of 2-ethylhexyl acrylate and 12 g of azobisisobutyronitrile were charged, and solution polymerization was carried out at 70 ° C. for 10 hours while introducing nitrogen while stirring them. Was. After the completion of the solution polymerization, NaOH (10% by weight) was added to the solution.
6 g of methanol solution) and stirred at 70 ° C. for 1 hour. After the treatment with the alkaline agent, the solution was transferred to a reduced pressure heating furnace, and methanol and methyl ethyl ketone were removed from the solvent to obtain a copolymer (weight average molecular weight = 50,000, Tg = 67).
° C). This copolymer was used as a charge control agent.

(Production and Evaluation of Toner) A toner was produced in the same manner as in Example 1 except that only the charge control agent was changed, and this was evaluated in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 (Production of Charge Control Agent) Stirrer, condenser, thermometer,
300 g of methanol in a 2 L flask equipped with a nitrogen inlet tube
And 100 g of methyl ethyl ketone, and 35% by weight of acrylamidomethylpropanesulfonic acid, 55% by weight of styrene, 2-ethylhexyl acrylate 1
600 g of a monomer mixture consisting of 0% by weight and 12 g of azobisisobutyronitrile were charged, and solution polymerization was carried out at 70 ° C. for 10 hours while introducing nitrogen while stirring them. After completion of the solution polymerization, 410 g of NaOH (10% by weight methanol solution) was added to the solution, followed by stirring at 70 ° C. for 1 hour. After the treatment with the alkaline agent, the solution was transferred to a reduced pressure heating furnace, and methanol and methyl ethyl ketone were removed from the solvent to obtain a copolymer (weight average molecular weight = 50,000, Tg = 78).
° C). This copolymer was used as a charge control agent.

(Production and Evaluation of Toner) A toner was manufactured in the same manner as in Example 1 except that only the charge control agent was changed, and the evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

[0053]

[Table 1]

[0054]

[Table 2]

As is evident from the results, the toner to which the charge control agent of the present invention is added has a small change in the charge amount under the conditions of high temperature, high humidity, and low temperature and low humidity. On the other hand, a toner to which a charge control agent comprising a copolymer containing no acrylamidomethylpropanesulfonate unit was added (Comparative Example 1), acrylamidomethylpropanesulfonic acid out of the range specified in the present invention, and The toners (Comparative Examples 2 and 3) to which a charge control agent obtained by treating a copolymer obtained with a charge ratio of another vinyl monomer copolymerizable with an alkali agent with a charge control agent were added at a high temperature, a high humidity and a low temperature. It can be seen that the change in charge amount under low humidity conditions is large.

[0056]

As described above, the charge control agent of the present invention is acrylamidomethylpropanesulfonate 1
To 30% by weight and a copolymer of 99 to 70% by weight of another vinyl monomer copolymerizable therewith, or 1 to 30% by weight of acrylamidomethylpropanesulfonic acid and another copolymerizable therewith Since it is a copolymer obtained by treating a copolymer with a vinyl-based monomer with 99 to 70% by weight with an alkali agent, the compatibility with the binder is good, and when the toner is formed into a toner, the charge control agent is converted from the toner. Never leave.
In addition, the colorant has good compatibility with the binder, and a colorless or light-colored transparent state can be obtained even when the binder and the negative charge control agent are mixed. Is obtained. In addition, since it has an acrylamidomethylpropanesulfonate unit, stable negative charging characteristics can be obtained, and the change in charge amount is small even due to environmental changes (high temperature, high humidity, low temperature, low humidity).

Further, the negatively charged toner for electrophotography of the present invention contains a binder and a charge control agent of the present invention, and the charge control agent is used in an amount of 0.1 to 100 parts by weight of the binder.
Since it is contained at 10 parts by weight, there is no change in the charge amount due to detachment of the charge control agent, and there is little change in the toner characteristics, especially the charge amount, at high temperature and high humidity or low temperature and low humidity, and it has excellent electrophotographic characteristics. It is. In addition, since a colorless or light-colored transparent state can be obtained even in the mixture of the binder and the negative charge control agent, when a color toner is formed, a colored toner capable of forming a clear color tone color image is obtained. It has a very good effect.

Claims (2)

[Claims] 1. A copolymer of 1 to 30% by weight of acrylamidomethylpropanesulfonic acid salt and 99 to 70% by weight of another vinyl monomer copolymerizable therewith, or 1 to 30% of acrylamidomethylpropanesulfonic acid. weight%
And other vinyl monomers 99 to 7 copolymerizable therewith.
A charge control agent comprising a copolymer obtained by treating 0% by weight of a copolymer with an alkali agent. 2. The composition according to claim 1, further comprising a binder and the charge control agent according to claim 1, wherein the charge control agent is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the binder. A negatively charged toner for electrophotography.