JP2011065058A - External additive for electrophotographic toner and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an external additive for an electrophotographic toner capable of imparting sufficient fluidity to electrophotographic toner particles. <P>SOLUTION: In a method for producing such an external additive for an electrophotographic toner containing acrylic polymer particles obtained by emulsion polymerization of a (meth)acrylic ester-based monomer in an aqueous medium in the presence of an ionic polymer and a water-soluble polymerization initiator, a 4 wt.% aqueous solution of the ionic polymer has a viscosity at 20°C of 2.0-10.0 mPa s, while the ionic polymer is used in an amount of 0.03-0.3 pt.wt. based on 100 pts.wt. of the (meth)acrylic ester-based monomer, and the acrylic polymer particles have an average particle diameter of 0.1-1.0 μm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external additive for an electrophotographic toner and a method for producing the same. Regarding the method.

  In electrophotography and electrostatic recording, an electrostatic charge image is formed on a photoreceptor or electrostatic recording body, and the electrostatic charge image is developed using electrophotographic toner by a magnetic brush development method, a cascade development method, or the like. As a result, a toner image is formed, and this is transferred and fixed on a copy paper or the like to form a copy. Various additives (hereinafter referred to as “electrophotographic toner external additive” or “toner external additive”) are added to the electrophotographic toner used in the electrophotographic method and the electrostatic recording method. Thus, it is known that the toner performance can be improved.

  The fine particles used as the external toner additive are required to have an average particle size smaller than that of the electrophotographic toner, to have a uniform shape and size, and to impart sufficient fluidity and chargeability to the toner. Such an external toner additive can improve various performances of the toner by entering between the toner particles to prevent adhesion between the toner particles or imparting fluidity to the toner.

  Conventionally, inorganic particles such as silica, titania, and alumina, or fine particles obtained by hydrophobizing the surface of these inorganic particles have been used as particles used for toner external additives. However, such an external additive for toner made of an inorganic material has a particle size of 0.1 μm or less and is too small and too hard to be externally added to the toner particles. There is a problem that the toner is easily embedded or easily detached from the toner particles, and sufficient fluidity cannot be imparted to the toner.

  As a technique for solving such a problem, an external toner additive made of styrene or acrylic polymer particles is known (see, for example, Patent Documents 1 and 2). Further, it is known that polymer particles are produced in the presence of a water-soluble polymer or a reactive surfactant and used as an external toner additive (see Patent Document 3).

JP 2001-163985 A JP 2001-272821 A Japanese Patent Publication No. 2-3172

However, in the methods of Patent Documents 1 and 2, since the polymer particles are produced by soap-free emulsion polymerization that does not use an emulsifier, the polymer particles easily aggregate during polymerization. Therefore, when this polymer particle is used as an external toner additive, sufficient fluidity cannot be imparted to the toner particle. Further, even when polymer particles obtained using a water-soluble polymer by the method of Patent Document 3 are used as an external toner additive, sufficient fluidity cannot be imparted to the toner particles. There are still many problems to be addressed in order to realize an external toner additive capable of imparting sufficient fluidity to the toner particles.
The present invention solves the above-described problems, and an object of the present invention is to provide an external additive for toner capable of imparting sufficient fluidity to an electrophotographic toner and a method for producing the same. It is in.

Thus, according to the present invention, an electrophotography comprising acrylic polymer particles obtained by emulsion polymerization of a (meth) acrylic ester monomer in an aqueous medium in the presence of an ionic polymer and a water-soluble polymerization initiator. A method for producing an external additive for toner, comprising:
The viscosity at 20 ° C. of a 4% by weight aqueous solution of the ionic polymer is 2.0 to 10.0 mPa · s,
The ionic polymer is used in an amount of 0.03 to 0.3 parts by weight based on 100 parts by weight of the (meth) acrylic ester monomer,
There is provided a method for producing an external additive for an electrophotographic toner, wherein the acrylic polymer particles have an average particle diameter of 0.1 to 1.0 μm.

  In addition, according to the present invention, there is provided an external additive for an electrophotographic toner obtained by the above production method.

According to the present invention, sufficient fluidity can be imparted to the toner particles used in the electrophotographic toner, and good development of an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing, etc. can be realized. Therefore, it is suitably used for toners for electrophotography, copying machines, printers, and the like.
Further, when the ionic polymer used in the present invention is ionic polyvinyl alcohol, the external additive for electrophotographic toner according to the present invention can impart further sufficient fluidity to the toner particles. .
Further, the external additive for electrophotographic toner according to the present invention externally adds the external additive for electrophotographic toner in an amount of 0.01 to 10.0 parts by weight with respect to 100 parts by weight of binder resin particles for electrophotographic toner. The resin particles thus obtained have a sieve passage rate of 45 μm or more and 75% or more, and it can be seen that sufficient fluidity can be imparted to the toner particles.

The external additive for an electrophotographic toner produced according to the present invention is an acrylic polymer obtained by emulsion polymerization of a (meth) acrylic ester monomer in an aqueous medium in the presence of an ionic polymer and a water-soluble polymerization initiator. It consists of system polymer particles.
The inventors of the present invention, when using a specific amount of an ionic polymer having a specific range of viscosity, provides fluidity of toner particles to which an external additive for electrophotographic toner composed of acrylic polymer particles is obtained. Surprisingly found that improved. In the case of conditions not specified in the present invention, that is, when an ionic polymer having a viscosity not in the specified range is used, and when the ionic polymer is used outside the specified amount range, It was also found that the effect of can not be obtained.

((Meth) acrylic ester monomers)
The (meth) acrylic ester monomer used in the present invention refers to an acrylic ester monomer and / or a methacrylic ester monomer.
The (meth) acrylic ester monomer used in the present invention is not particularly limited. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) N-butyl acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, (meth) acrylic acid Examples include isodecyl, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. These (meth) acrylic ester monomers may be used alone or in combination.

Other monomers and additives may be added to the (meth) acrylic ester monomer used in the present invention as long as the effects of the present invention are not impaired.
Examples of other monomers include bifunctional polymerizable vinyl monomers and styrene monomers. Specifically, examples of the bifunctional polymerizable vinyl monomer include divinyl benzene and alkylene glycol dimethacrylate (alkylene preferably has a range of 2 to 4 carbon atoms). Examples of the styrene monomer include styrene, α -Aromatic vinyl compounds such as methylstyrene, vinyltoluene and chlorostyrene. The mixing ratio of the bifunctional polymerizable vinyl monomer is preferably 50 parts by weight or less, more preferably 0.1 to 40 parts by weight with respect to 100 parts by weight of the (meth) acrylic ester monomer.

  Examples of other additives include a light stabilizer, an ultraviolet absorber, a pigment, a dye, an antifoaming agent, a thickener, a heat stabilizer, a leveling agent, a lubricant, and an antistatic agent.

(Aqueous medium)
Examples of the aqueous medium used in the present invention include water or a mixture of water and an organic solvent (for example, a lower alcohol).

(Ionic polymer)
The ionic property of the ionic polymer can indicate a value of zeta potential of an aqueous solution in which 5 g of a sample is dissolved in 100 g of distilled water is +1 mV or more (cationic) or −1 mV or less (anionic). Show things. The zeta potential here is measured by a laser Doppler velocity measurement method. If the substance is charged, the substance moves toward the electrode when an electric field is applied to the aqueous solution. The moving speed of the substance is proportional to the charge amount of the substance. Therefore, the zeta potential can be obtained by measuring the moving speed of the substance. This measurement can be easily performed with a commercially available measuring apparatus. In the present invention, “Zeta Sizer Nano ZS” manufactured by Malvern is used.

  In the present invention, an ionic polymer having a specific viscosity range is used. The viscosity within a specific range means that the viscosity at 20 ° C. of a 4% by weight aqueous solution of an ionic polymer is 2.0 to 10.0 mPa · s. When the viscosity is less than 2.0 mPa · s, the dispersion stability of the polymer particles obtained in the emulsion polymerization may be impaired. In this case, aggregation of the polymer particles after the polymerization may occur, so that sufficient fluidity may not be imparted to the toner. On the other hand, if the viscosity is greater than 10.0 mPa · s, the adhesive force of the polymer particles becomes too strong, and thus sufficient fluidity may not be imparted to the toner. Therefore, the viscosity of the ionic polymer in the present invention is preferably in the range of 2.0 to 10.0 mPa · s, and particularly preferably in the range of 2.4 to 8.0 mPa · s.

  Examples of the ionic polymer used in the present invention include ionic polyvinyl alcohol, ionic cellulose, ionic acrylic resin, and ionic polystyrene resin. Among these, ionic polyvinyl alcohol is particularly preferable because particularly high fluidity can be imparted. If a nonionic polymer is used, the charge repulsion effect cannot be obtained in emulsion polymerization, and thus the polymerization stability may be deteriorated. In this case, aggregation of the polymer particles after the polymerization may occur, so that sufficient fluidity may not be imparted to the toner. Therefore, it is not preferable to use a nonionic polymer in the present invention.

  Specific examples of the ionic polymer include sulfonic acid group-modified polyvinyl alcohol, amino group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, sodium carboxymethylcellulose, sodium polyglutamate, sodium polyaspartate, polylactic acid, and polystyrenesulfonic acid. Examples thereof include sodium, ammonium polystyrene sulfonate, sodium polyacrylate, ammonium polyacrylate, polysodium methacrylate, and polyammonium methacrylate. Among these, sulfonic acid group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, and sodium carboxymethylcellulose are particularly preferable. These may be used alone or in combination.

  In the present invention, if the amount of the ionic polymer used is too small, the dispersion stability of the particles may be impaired. In this case, aggregation of the polymer particles after the polymerization may occur, so that sufficient fluidity may not be imparted to the toner. On the other hand, if the amount is too large, the adhesive force of the polymer particles becomes too strong, so that sufficient fluidity may not be imparted to the toner. Accordingly, the amount of the ionic polymer used in the present invention is preferably 0.03 to 0.3 parts by weight, particularly 0.05 to 0.2 parts by weight, based on 100 parts by weight of the (meth) acrylic ester monomer. preferable.

(Water-soluble polymerization initiator)
In the present invention, a water-soluble polymerization initiator is used as the polymerization initiator. The water-soluble polymerization initiator used in the present invention is not particularly limited. For example, 2,2-azobis [2- (2-imidazolin-2-yl) propane] dichloride is known as a known one. Hydrogen, 2,2-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2-azobis (2-amidinopropane) hydrogen dichloride, 2,2-azobis [N -(2-carboxyethyl) -2-methylpropionamidine] hydrate, 2,2-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} hydrogen dichloride, 2,2-azobis [2- (2-imidazolin-2-yl) propane], 2,2-azobis (1-imino-1-pyrrolidino-2-ethylpropane) hydrogen dichloride, 2,2-azobis {2 -Methyl-N [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2-azobis (N- Hydroxyethylisobutyramide), 4,4-azobis (4-cyanopentanoic acid), azobisisobutyronitrile, azobis (2,4dimethylvaleronitrile) and other azo compounds, ammonium persulfate, potassium persulfate, persulfate Examples thereof include persulfates such as sodium, and organic peroxides such as benzoyl peroxide, acetyl peroxide, methyl ethyl ketone peroxide, t-butyl peroxide, and dicumyl peroxide.

  The amount of the water-soluble polymerization initiator used in the present invention varies depending on the type of the water-soluble polymerization initiator, but is 0.1 to 5 parts by weight with respect to 100 parts by weight of the (meth) acrylic ester monomer. It is preferable. More preferably, it is 0.3 to 3 parts by weight.

(Emulsion polymerization)
In the present invention, the polymerization is carried out by emulsion polymerization. Emulsion polymerization is a polymerization method in which an aqueous medium, a monomer that is difficult to dissolve in the medium, and an emulsifier (surfactant) are mixed, and a polymerization initiator that is soluble in the medium is added to the mixture. Advantages of emulsion polymerization include that a polymer having a high degree of polymerization can be easily obtained at a high speed and that the temperature can be easily adjusted in order to obtain an aqueous medium.

  When emulsion polymerization is performed in the present invention, a chain transfer agent may be added. Although it does not specifically limit as a chain transfer agent used by this invention, For example, alkyl mercaptans, such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, etc. , Α-methylstyrene dimer, 2,6-di-t-butyl-4-methylphenol, phenolic compounds such as styrenated phenol, allyl compounds such as allyl alcohol, halogenated dichloromethane, dibromomethane, carbon tetrachloride, etc. A hydrocarbon compound is mentioned. The addition amount of the chain transfer agent is preferably 0.1 to 5 parts by weight, and more preferably 0.3 to 3 parts by weight with respect to 100 parts by weight of the (meth) acrylic ester monomer.

  In the emulsion polymerization performed in the present invention, the ratio of the (meth) acrylic ester monomer to the aqueous medium is preferably in the range of 1:20 to 1: 2 (weight ratio). When the ratio of the (meth) acrylic ester monomer is less than 1:20, the productivity may be deteriorated, and when the ratio of the (meth) acrylic ester monomer is larger than 1: 2, the stability of the particles during polymerization is increased. This is not preferable because the polymer particles may deteriorate and an aggregate of polymer particles may be formed after polymerization. A more preferable use ratio is in the range of 1:15 to 1: 3 (weight ratio).

  In the emulsion polymerization carried out in the present invention, the stirring rotation speed is preferably 100 to 500 rpm, for example, when a 5 liter reactor is used. Moreover, although superposition | polymerization temperature changes with kinds of the monomer and polymerization initiator to be used, it is preferable that it is 30-100 degreeC. The polymerization time is preferably 2 to 10 hours.

  The method for isolating the acrylic polymer particles obtained from the aqueous medium by the emulsion polymerization performed in the present invention is not particularly limited, but a known method is, for example, a spray drying method represented by a spray dryer. Examples thereof include a method of adhering to a heated rotating drum typified by a drum dryer and drying or a freeze-drying method. It is desirable that the acrylic polymer particles isolated from the aqueous medium be deagglomerated by a pulverizer or a pulverizer.

  The average particle diameter of the acrylic polymer particles obtained by the emulsion polymerization performed in the present invention is 0.1 to 1.0 μm. If it is less than 0.1 μm, the resulting polymer particles are likely to aggregate, and sufficient fluidity may not be imparted to the toner. On the other hand, if the thickness is larger than 1.0 μm, detachment from the toner tends to occur, so that sufficient fluidity may not be imparted to the toner. About the measuring method of an average particle diameter, it describes in the below-mentioned Example.

  The acrylic polymer particles obtained by the emulsion polymerization carried out in the present invention are separated from the acrylic polymer particles in an amount of 0.01 to 10.0 parts by weight with respect to 100 parts by weight of the binder resin particles for electrophotographic toner. The resin particles obtained by addition are used as an external additive for an electrophotographic toner having a sieve passage rate of 45 μm and 75% or more.

  As a specific example, when 0.3 part by weight of the acrylic polymer particles obtained by the present invention is externally added to 100 parts by weight of a styrene-acrylic resin having an average particle diameter of 10 μm as a binder resin for an electrophotographic toner, When the sieve passing rate of a styrene-acrylic resin with an opening of 45 μm is measured, it is 75% or more. When the sieve passing rate is less than 75%, the fluidity as toner particles becomes insufficient, and when the copy is transferred and fixed on a copy paper or the like to produce a copy, the image quality and density of the copy are reduced. It may get worse. The method for measuring the sieve passage rate will be described in the examples described later.

  The external addition method of the external additive for the electrophotographic toner to the binder resin particles for the electrophotographic toner is not particularly limited, and is carried out by a known method and conditions such as a mechanical pulverization and mixing method. May be. Specifically, the acrylic polymer particles and the binder resin for electrophotographic toner are mixed and stirred using a mill mixer, a Henschel mixer, a V-type mixer, a turbula mixer, a hybridizer, a rocking mixer, or the like.

(Binder resin particles for electrophotographic toner)
The binder resin particles for electrophotographic toner used in the present invention are not particularly limited. For example, styrene resin, styrene-acrylic resin, styrene-butadiene resin, styrene-maleic resin, styrene-vinylmethyl. Synthetic resins such as ether resins, styrene-methacrylic ester resins, polyester resins, phenol resins, and epoxy resins can be mentioned.

  If the amount of the external additive for electrophotographic toner added to the binder resin particle for electrophotographic toner in the present invention is too small, sufficient fluidity may not be imparted to the binder resin particle for electrophotographic toner. On the other hand, if the amount is too large, the amount of desorption from the binder resin particles for electrophotographic toner may increase. Accordingly, it is preferable to add 0.01 to 10.0 parts by weight of an external additive for electrophotographic toner to 100 parts by weight of binder resin particles for electrophotographic toner, and more preferably 0.2 to 5 parts by weight. It is.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

First, a method for measuring the viscosity of an ionic polymer, a method for measuring an average particle size, and a method for evaluating polymerization stability and fluidity in Examples and Comparative Examples will be described.
(Measurement method of viscosity of ionic polymer)
4 g of ionic polymer is dissolved in 100 g of pure water, and the viscosity of this aqueous solution at 20 ° C. is measured with a tuning-fork vibration viscometer (A & D, VIBRO VISCOMETER SV-10). The obtained value is the viscosity at 20 ° C. of a 4% by weight aqueous solution of the ionic polymer.

(Measurement method of average particle size)
The average particle diameter here means a particle diameter measured using a method called a dynamic light scattering method or a photon correlation method. Specifically, an aqueous dispersion of acrylic polymer particles obtained by emulsion polymerization was diluted 200 times with ion-exchanged water to prepare 0.1 wt%, and irradiated with laser light at 25 ° C. The intensity of the scattered light scattered from the coalesced particles is measured with a time change in units of microseconds. The numerical value calculated by the cumulant analysis method for the distribution of scattering intensity caused by the measured polymer resin particles is the average particle diameter. The cumulant analysis method is a method of analyzing by applying a normal distribution to calculate the average particle size. The average particle diameter by this method can be easily measured with a commercially available measuring apparatus. In the examples of the present invention, “Zetasizer Nano ZS” manufactured by Malvern is used for measurement. Such a commercially available measuring apparatus is equipped with data analysis software, and the measured data is automatically analyzed.

(Evaluation method for polymerization stability)
First, the entire aqueous dispersion of acrylic polymer particles obtained by emulsion polymerization is passed through a stainless steel sieve having an opening of 100 μm. Next, the residue on the sieve is dried at 50 ° C. for 24 hours, and the weight of the residue after drying is weighed. The weight (Wa) of the residue after drying is divided by the total weight of the (meth) acrylic ester monomer used in the emulsion polymerization, and a value obtained by multiplying this by 100 is defined as the aggregate production rate.
Aggregate production rate (%) = (Wa / (meth) acrylic ester monomer total weight) × 100
When this aggregate formation rate is less than 1%, it is judged that the polymerization stability is very excellent (◎), and when it is 1% or more, the polymerization stability is judged as poor (x).

(Evaluation method for fluidity)
In the present invention, the fluidity is evaluated by the sieve passing rate. The sieve passing rate as used in the field of this invention means the measured value of the sieve passing rate by the powder tester made from Hosokawa Micron Corporation. As a measurement sample, an external additive for an electrophotographic toner composed of acrylic polymer particles obtained in Examples and Comparative Examples of the present invention was externally added to toner binder resin particles (hereinafter referred to as “pseudo”). Called "toner"). The pseudo toner is evaluated from the measured value of the sieve passing rate.
The pseudo toner production method (a) and sieve passing rate measurement method (b) will be described below.

(A) Method for producing pseudo toner In a 5 L autoclave, 26 parts by weight of magnesium pyrophosphate was dispersed in 2600 parts by weight of water, 0.13 parts by weight of sodium nitrite and phosphanol LO-529 (manufactured by Toho Chemical Co., Ltd.) 1.3 parts by weight are dissolved. A mixed solution of 910 parts by weight of styrene and 390 parts by weight of butyl methacrylate in which 10.4 parts by weight of azobisisobutyronitrile, 3.9 parts by weight of t-butylperoxy-2-ethylhexanoate was dissolved. Is added and emulsified with a homogenizer at 4000 rpm. By treating the emulsified material with a nanomizer system LA-33 (manufactured by Nanomizer) at a treatment pressure of 0.5 MPa, a dispersion can be obtained. The resulting dispersion is heated at 60 ° C. for 6 hours while stirring at a stirring speed of 450 rpm. Thereafter, 1.3 parts by weight of sulfamic acid and 100 parts by weight of water in which 2.6 parts by weight of sodium dodecylbenzenesulfonate are dissolved are added, and the mixture is heated to 110 ° C. and further polymerized while continuing stirring for 1 hour. Thereafter, the binder resin for toner is obtained by cooling to room temperature and performing dehydration and drying. The obtained binder resin for toner has an average particle size of 10 μm.
A mixture of 15 g of the binder resin for toner and 0.45 g of the external additive for electrophotographic toner of the present invention was mixed for 5 seconds with a mill mixer (MX-X57-Y fiber mixer manufactured by National), and then allowed to stand for 1 minute. To do. The pseudo toner is obtained by repeating the operation 5 times in total by mixing again for 5 seconds and standing for 1 minute, and repeating this operation a total of 5 times.

(B) Method for Measuring Screen Passage First, 2 g of the pseudo toner obtained by the production method (a) is placed on a metal screen having an opening of 45 μm. Next, a rheostat voltage of 7.2 V is applied to a powder tester manufactured by Hosokawa Micron, and the sieve is vibrated for 93 seconds. After the vibration is finished, the weight of the powder remaining on the sieve is measured, and the value calculated by the following formula is defined as the sieve passing rate.
Sieve passing rate (%) = 100 − {(weight of powder remaining on sieve / 2 g) × 100}
The measured value of the passing rate of the pseudo toner is evaluated according to the following criteria.
A: Very good fluidity can be imparted (sieving rate of 85% or more)
○: Excellent fluidity can be imparted (sieving rate 75% or more and less than 85%)
X: Poor fluidity (sieving rate less than 75%)

Example 1
In a 1 L three-necked separable flask equipped with a stirrer, a reflux condenser and a thermometer, 400 parts by weight of ion-exchanged water and a viscosity at 20 ° C. of a 4% by weight aqueous solution as an ionic polymer are 2.5 mPa · s. 0.1 part by weight of a certain sulfonic acid group-modified polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd., Gocelan L-3266), 30 parts by weight of methyl methacrylate and 70 parts by weight of isobutyl methacrylate were supplied. Then, it heated at 70 degreeC, stirring at 250 rpm of stirring rotation speed. Next, 0.5 part by weight of ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) was added as a water-soluble polymerization initiator, and stirring was continued for 2 hours. Thereafter, stirring was further continued at 80 ° C. for 1 hour, and finally, the mixture was cooled to room temperature to obtain an aqueous dispersion of an external additive for toner. The resulting toner external additive had an average particle size of 0.32 μm, an aggregate formation rate of 0.6%, and a polymerization stability of ◎. The obtained aqueous dispersion of the toner external additive was dried by a spray dryer. The powder remaining after drying was treated with an airflow pulverizer to take out the external additive for toner.
A pseudo toner was prepared using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 94%, which was in the range of evaluation (85% or more) that “◎: can impart very good fluidity”.

(Example 2)
Except that 0.2 parts by weight of a sulfonic acid group-modified polyvinyl alcohol having a viscosity at 20 ° C. of a 4% by weight aqueous solution of 2.5 mPa · s was used, all of the toner external additive water was used under the same conditions as in Example 1. A dispersion was obtained. The resulting toner external additive had an average particle size of 0.29 μm, an aggregate formation rate of 0.5%, and a polymerization stability of ◎. The toner external additive was taken out from the obtained aqueous dispersion of the toner external additive in the same process as in Example 1. Subsequently, a pseudo toner was produced using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 91%, which was within the range of evaluation (85% or more) that “◎: can impart very excellent fluidity”.

(Example 3)
Except that 0.05 parts by weight of a sulfonic acid group-modified polyvinyl alcohol having a viscosity of 2.5 mPa · s at 20 ° C. in a 4% by weight aqueous solution was used, all of the toner external additive water was used under the same conditions as in Example 1. A dispersion was obtained. The resulting toner external additive had an average particle size of 0.36 μm, an aggregate formation rate of 0.8%, and a polymerization stability of ◎. The toner external additive was taken out from the obtained aqueous dispersion of the toner external additive in the same process as in Example 1. Subsequently, a pseudo toner was produced using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 90%, and was in the range of evaluation (85% or more) “「: Can impart very excellent fluidity ”.

Example 4
An aqueous dispersion of the toner external additive was obtained under the same conditions as in Example 1 except that 100 parts by weight of methyl methacrylate was used instead of 30 parts by weight of methyl methacrylate and 70 parts by weight of isobutyl methacrylate. . The resulting toner external additive had an average particle size of 0.28 μm, an aggregate formation rate of 0.4%, and a polymerization stability of ◎. The toner external additive was taken out from the obtained aqueous dispersion of the toner external additive in the same process as in Example 1. Subsequently, a pseudo toner was produced using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 91%, which was within the range of evaluation (85% or more) that “◎: can impart very excellent fluidity”.

(Example 5)
Instead of the sulfonic acid group-modified polyvinyl alcohol whose viscosity at 20 ° C. of the 4 wt% aqueous solution is 2.5 mPa · s, the sulfonic acid group modified polyvinyl alcohol whose viscosity at 20 ° C. of the 4 wt% aqueous solution is 6.4 mPa · s. Except that Kuraray Co., Ltd. (KL-506) was used, an aqueous toner dispersion was obtained under the same conditions as in Example 1. The resulting toner external additive had an average particle size of 0.29 μm, an aggregate formation rate of 0.7%, and a polymerization stability of ◎. The toner external additive was taken out from the obtained aqueous dispersion of the toner external additive in the same process as in Example 1. Subsequently, a pseudo toner was produced using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 87%, which was within the range of evaluation (85% or more) that “◎: can impart very excellent fluidity”.

(Example 6)
Instead of sulfonic acid group-modified polyvinyl alcohol having a viscosity of 2.5 mPa · s at 20 ° C. in a 4% by weight aqueous solution, sodium carboxymethylcellulose having a viscosity of 9.5 mPa · s at 20 ° C. in a 4% by weight aqueous solution (Daicel Chemical) An aqueous dispersion of an external additive for toner was obtained under the same conditions as in Example 1 except that CMC Daicel 1120) manufactured by the company was used. The resulting toner external additive had an average particle size of 0.34 μm, an aggregate formation rate of 0.8%, and a polymerization stability of ◎. The toner external additive was taken out from the obtained aqueous dispersion of the toner external additive in the same process as in Example 1. Subsequently, a pseudo toner was produced using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 82%, which was within the range of evaluation (“75: Can give excellent fluidity”) (75% or more and less than 85%).

(Comparative Example 1)
Except that 0.01 parts by weight of a sulfonic acid group-modified polyvinyl alcohol having a viscosity of 2.5 mPa · s at 20 ° C. in a 4% by weight aqueous solution was used, the toner external additive water was used under the same conditions as in Example 1. A dispersion was obtained. The resulting toner external additive had an average particle size of 1.2 μm, an aggregate formation rate of 3.5%, and a polymerization stability of x. The toner external additive was taken out from the obtained aqueous dispersion of the toner external additive in the same process as in Example 1. Subsequently, a pseudo toner was produced using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 73%, which was in the range of evaluation “X: poor in imparting fluidity” (less than 75%).

(Comparative Example 2)
Except that 0.5 parts by weight of a sulfonic acid group-modified polyvinyl alcohol having a viscosity of 2.5 mPa · s at 20 ° C. in a 4% by weight aqueous solution was used, the toner external additive water was used under the same conditions as in Example 1. A dispersion was obtained. The resulting toner external additive had an average particle size of 0.28 μm, an aggregate formation rate of 0.7%, and a polymerization stability of ◎. The toner external additive was taken out from the obtained aqueous dispersion of the toner external additive in the same process as in Example 1. Subsequently, a pseudo toner was produced using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 71%, and was in the range of evaluation (“less than imparting fluidity”) (less than 75%).

(Comparative Example 3)
Instead of the sulfonic acid group-modified polyvinyl alcohol whose viscosity at 20 ° C. of the 4% by weight aqueous solution is 2.5 mPa · s, the sulfonic acid group-modified polyvinyl alcohol whose viscosity at 20 ° C. of the 4% by weight aqueous solution is 18 mPa · s (Japan) An aqueous dispersion of an external additive for toner was obtained under the same conditions as in Example 1 except that Synthetic Chemical Co., Ltd., L-0302) was used. The resulting toner external additive had an average particle size of 0.45 μm, an aggregate formation rate of 0.8%, and a polymerization stability of ◎. The toner external additive was taken out from the obtained aqueous dispersion of the toner external additive in the same process as in Example 1. Subsequently, a pseudo toner was produced using the obtained external additive for toner, and the sieve passing rate was measured. The sieve passing rate was 66%, which was in the range of evaluation (less than 75%) “x: poor fluidity provision”.
The above Examples 1 to 6 and Comparative Examples 1 to 3 are shown together in Table 1.

ＩＢＭＡ：メタクリル酸イソブチル
ＭＭＡ：メタクリル酸メチル

IBMA: Isobutyl methacrylate MMA: Methyl methacrylate

As a result (evaluation) of Comparative Examples 1 and 2, the range of the ionic polymer used for 100 parts by weight of the (meth) acrylic ester monomer is within the range of the present invention (0.03 to 0.3 parts by weight). This is probably due to being outside.
The result (evaluation) of Comparative Example 3 is considered to result from the fact that the viscosity of the ionic polymer was outside the range of the present invention (2.0 to 10.0 mPa · s).

Claims (4)

Production of an external additive for an electrophotographic toner comprising acrylic polymer particles obtained by emulsion polymerization of a (meth) acrylic ester monomer in an aqueous medium in the presence of an ionic polymer and a water-soluble polymerization initiator. A method,
The viscosity at 20 ° C. of a 4% by weight aqueous solution of the ionic polymer is 2.0 to 10.0 mPa · s,
The ionic polymer is used in an amount of 0.03 to 0.3 parts by weight based on 100 parts by weight of the (meth) acrylic ester monomer,
The method for producing an external additive for an electrophotographic toner, wherein the acrylic polymer particles have an average particle diameter of 0.1 to 1.0 μm.   The method for producing an external additive for an electrophotographic toner according to claim 1, wherein the ionic polymer is ionic polyvinyl alcohol.   An external additive for an electrophotographic toner obtained by the method according to claim 1 or 2.   The external additive for electrophotographic toner is obtained by externally adding the external additive for electrophotographic toner in an amount of 0.01 to 10.0 parts by weight with respect to 100 parts by weight of binder resin particles for electrophotographic toner. The external additive for electrophotographic toner according to claim 3, wherein the resin particles have a sieve passage rate of 75 µm or more with an opening of 45 µm.