JP3438793B2 - Negative toner for electrophotography - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry toner used for electrophotographic development.

[0002]

2. Description of the Related Art In electrophotography, dry developers include a one-component developer that uses a toner itself containing a colorant and a binder resin as main components, and a two-component developer that is a mixture of the toner and a carrier. It can be roughly divided.

As a method for producing a toner, a so-called pulverization method in which a binder resin, a colorant and the like are kneaded and pulverized and classified is widely practiced. However, a so-called heavy weight method in which the colorant and the like are incorporated during polymerization to obtain fine particles. Legalization has begun to be implemented in some areas. As a new method different from these, Japanese Patent Laid-Open No. 5-6660
There is a so-called phase inversion emulsification method described in Japanese Patent Publication No. 0 and the like.

This is because an anion type self-water dispersible resin, a colorant and the like are dissolved and dispersed in an organic solvent, and an appropriate amount of water is added thereto with stirring to carry out phase inversion emulsification to produce fine particles. This is a method of drying to obtain a dry toner (hereinafter referred to as a phase inversion emulsification method toner).

[0005]

With respect to the toner of the phase inversion emulsification method produced in this manner, a means for improving the charging property in the negative direction is expected. In particular, such a phase inversion emulsified toner has a problem that the charging performance required as a non-magnetic one-component developer cannot be obtained.

[0006]

Therefore, the present inventor diligently studied a method for improving the chargeability of the fine particles obtained by the phase inversion emulsification method in the negative direction, and found that the primary particles were hydrophobic with a specific average diameter. It has been found that by externally adding silica, the chargeability of the fine particles obtained by the phase inversion emulsification method can be improved in the negative direction.

The present inventor has also earnestly studied a method in which fine particles obtained by the phase inversion emulsification method can be used as a non-magnetic one-component developer. By adding it, it was found that it can be used as a non-magnetic one-component developer, and the present invention has been completed. That is, in the present invention, the colorant (A) is neutralized
The resin (B) which can be anionic self-water dispersible by
For binding resin (C) containing at least 25% by weight
The average diameter of the primary particles is 5 in the encapsulated spherical fine particles (D).
~ 30 nanometer hydrophobic silica (E), or 5
~ 30 nanometer hydrophobic silica (E) and 30 nanometer
Over 40 nanometers of hydrophobic silica
Both (F) of the coloring agent (A) and the binder resin (C)
0.1 to 3.0 parts by weight was added externally per 100 parts by weight in total.
Provide negative toner for electrophotographic non-magnetic one-component development
Especially.

There are a two-component developing method and a one-component developing method as a method of developing an electrostatic charge image formed on the surface of a photoreceptor in electrophotography. In the magnetic brush developing method, which is the mainstream of the two-component developer method, the dry toner is charged by friction with a carrier composed of magnetic particles (about 20 to 200 microns) such as iron powder and ferrite to form a magnetic brush. As a result, only the toner adheres to the photoconductor and development is performed.

On the other hand, a one-component developing system using a magnetic toner mainly composed of resin and magnetic powder or a one-component developing system consisting only of non-magnetic toner has been put into practical use. As a one-component developing method using a non-magnetic toner, a contact-type non-magnetic one-component developing method in which a developing sleeve carrying a developer is brought into contact with a photosensitive drum having an electrostatic latent image for development has been widely put into practical use. There is.

[0010] The toner of the present invention, passed through a toner between the charging member is pressed against it and the current image the sleeve, by frictional charging of the toner, developing the electrostatic latent image formed on the surface of the photosensitive member It is suitable for such a contact type non-magnetic one-component developing method.

The spherical fine particles (D) used in the present invention are encapsulated in a binder resin (C) containing a synthetic resin (B) in which the colorant (A) becomes anionic by neutralization and is self-dispersible in water. It is a spherical fine particle with a structured structure.

Colorant (A) used in the present invention
The pigment is not particularly limited, and examples thereof include various pigments and dyes known and commonly used as toner materials such as carbon black, copper phthalocyanine pigments, azo pigments, benzidine pigments, and quinacridone pigments. The content of the colorant (A) is preferably 3 to 15% with respect to the total weight of the colorant (A) and the binder resin (C).

First, the resin (B) used in the present invention which can be anionic self-water dispersible by neutralization is a resin containing a functional group which can be anionic hydrophilic group by neutralization. A resin that can form a stable aqueous dispersion under the action of an aqueous medium without using an emulsifier when a part or all of the functional groups that can become acidic are neutralized with a base.

Examples of the functional group capable of becoming an anionic hydrophilic group by neutralization in the resin (B) include a carboxyl group, a phosphoric acid group, a sulfonic acid group and a sulfuric acid group.

Examples of the resin (B) capable of becoming anionic water-dispersible by neutralization include acrylic resins, styrene resins, polyester resins, epoxy resins, polyurethane resins and the like. Of these, styrene resins and acrylic resins are preferable because they have excellent moisture absorption resistance.

The styrene resin and acrylic resin suitable as the resin (B) include, for example, an acid group-containing polymerizable monomer and a polymerizable monomer other than the acid group-containing polymerizable monomers. , Those obtained by copolymerization in the presence of a polymerization initiator, and the like.

Examples of the acid group-containing polymerizable monomers include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monobutyl itaconate, monobutyl maleate, acid phosphooxyethyl methacrylate and acid. Examples include phosphooxypropyl methacrylate, 3-chloro-2-acrylamido-2-methylpropane sulfonic acid or 2-sulfoethyl methacrylate.

Examples of the polymerizable monomers other than the acid group-containing polymerizable monomers include styrene, vinyltoluene and 2-
Various styrene-based monomers (aromatic vinyl monomers) such as methylstyrene, t-butylstyrene or chlorostyrene; methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate,
Various acrylates such as isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate or dodecyl acrylate; methacryl Methyl acid, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, decyl methacrylate or dodecyl methacrylate. , Various methacrylic acid esters; various hydroxyl group-containing monomers such as hydroxyethyl acrylate or hydroxypropyl methacrylate, or N-methylol (meth) acrylic acid Such de or N- butoxymethyl (meth) acrylamide, various N- substituted (meth) acrylic monomers and the like.

As the polymerization initiator to be used, of course, usual ones can be used. For example, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, t-butyl peroxide or 2-ethylhexano. Various peroxides such as ate; various azo compounds such as azobisisobutyronitrile or azobisisovaleronitrile.

Examples of the organic solvent which can be used in the above reaction include various aromatic hydrocarbons such as toluene, xylene or benzene; various alcohols such as methanol, ethanol, propanol or butanol; cellosolve or Various ether alcohols such as carbitol; acetone, methyl ethyl ketone or methyl isobutyl ketone,
Examples include various ketones; various esters such as ethyl acetate or butyl acetate; and various ether esters such as butyl cellosolve acetate. Of course, these can also be used when preparing an organic solvent solution of the binder resin (C) described later.

The content of the functional group capable of becoming an anionic hydrophilic group by the neutralization of the resin (B) is not particularly limited, but an acid value of about 40 or more facilitates the formation of fine particles by the phase inversion emulsification method. preferable. Particularly preferably, the acid value is 50 to
It is 150.

The polymerization condition of the binder resin (C) is usually 50.
It is generally performed in a temperature range of 150 ° C. to 150 ° C. under a nitrogen atmosphere. In addition, since the binder resin (C) becomes capsule-type fine particles, the molecular weight is at a level sufficient for the capsule wall, and usually 5,000 to 2000 as the weight average molecular weight.
00, preferably 10,000 to 150,000.

The binder resin (C) used in the present invention may be the above resin (B) alone, or 25% by weight or more of the resin (B) and other synthetic resin 75.
It may consist of less than wt% of the mixture. Resin (B)
, When constituting the binder for <br/> resin (C) parts of a combination of other resin spherical fine particles (D) may be a more and they are compatible, with incompatible It may have a multilayer structure.

As used herein, "other resin" means
For example, an anion type self-water dispersible resin and a hydrophobic synthetic resin can be mentioned. Examples of such materials include acrylic resins, styrene resins, polyester resins, epoxy resins, polyurethane resins and the like other than the above.
When the spherical fine particles ( D ) have a multi-layered structure, for example, a hydrophobic synthetic polymerized by removing the acid group-containing polymerizable monomers from the monomer composition of the resin (B) described above. Resin can be used.

The spherical fine particles ( D ) are the binder resin (C).
May be spherical fine particles (D) having a uniform composition of the resin (B) containing the colorant (A), and the binding resin (C) may be an anion. The mixture of the mold self-water-dispersible resin and the hydrophobic synthetic resin may be core-shell type multilayer spherical fine particles (D) in which the hydrophobic synthetic resin is the core portion and the resin (B) is the shell portion.

The spherical fine particles (D) of the present invention may be produced by any method, but are preferably produced by a phase inversion emulsification method.

Therefore, a method for forming spherical fine particles (D) by the phase inversion emulsification method used in the present invention will be described. First, the colorant (A) is thoroughly mixed and dispersed in an organic solvent solution of the binder resin (C), and then a base is added to neutralize the resin (B) to obtain an anionic self-water-dispersible resin. .

As the organic solvent used in preparing the organic solvent solution, the reaction solvent used in the synthesis of the binder resin (C) may be used as it is. Above all, it is preferable to use a so-called low boiling point solvent such as acetone, isopropyl alcohol, methyl ethyl ketone or ethyl acetate, which is easily desolvated.

To this organic solvent solution, an appropriate amount of water is added dropwise with stirring, or by injecting this into water, phase inversion emulsification is carried out. Then, after removing the solvent,
It is neutralized with an acid, filtered, dehydrated and then dried to obtain spherical fine particles (D).

Examples of the base include triethylamine, sodium hydroxide, ammonia and the like, and examples of the acid include hydrochloric acid, sulfuric acid and the like. These neutralizing agents can be used, for example, in the form of an aqueous solution.

When a mixture of an anionic self-water dispersible resin and a hydrophobic synthetic resin is used as the binder resin (C) used during the phase inversion emulsification, the ratio of the anionic self water dispersible resin is 25. When used in an amount of not less than 10% by weight, good spherical core-shell type multilayer fine particles are finally formed.

The spherical fine particles (D) used in the present invention are Wader's practical sphericity (ratio between the diameter of a circle having an area equal to the projected area of the particle and the diameter of the smallest circle circumscribing the projected image of the particle). Is 0.95 to 1.00 and the average particle size is preferably about 4 to 15 μm.

The toner of the present invention has an average primary particle size of 5
A major feature is the use of ~ 30 nanometer hydrophobic silica (E).

The hydrophobic silica (E and F) used in the present invention means one having a hydrophobic property among silicon dioxides. For example, silicon dioxide is used as various polyorganosiloxanes or silane coupling agents. The thing which surface-treated is mentioned. Examples of the hydrophobic silica (E) having an average primary particle diameter of 5 to 30 nanometers include those commercially available under the following trade names.

AEROSIL R972, R974, R
202, R805, R812, RX200, RY200
[Japan Aerosil Co., Ltd.] WACKER HDK H2000, H2050EP
[Wacker Chemicals East Asia Co., Ltd.] Nipsil SS-10, SS-15, SS-20,
SS-50, SS-60, SS-100, SS-50
B, SS-50F, SS-10F [Nippon Silica Industry Co., Ltd.]

Examples of the hydrophobic silica (F) having an average primary particle size of more than 30 nanometers include those commercially available under the following trade names.

AEROSIL R809, RX50
[Japan Aerosil Co., Ltd.] Nipsil SS-40, SS-70, SS-72
F [Nippon Silica Industry Co., Ltd.]

The hydrophobic silica (E) may be used alone or in combination with the hydrophobic silica (F) having a large particle size of more than 30 nanometers.

As the externally added amount of the hydrophobic silica (E), the charge amount becomes necessary and sufficient, which does not damage the photosensitive drum or deteriorate the environmental characteristics of the toner. Therefore, the coloring agent (A) is used. 0.1 to 3.0 parts by weight, and especially 0.3 to 3.0 parts by weight, based on 100 parts by weight of the binder resin (C).
The parts by weight are practically optimal.

Of course, when silica (F) is used in combination with silica (E), it is preferable that the total weight parts thereof be within the above range.

As a method for externally adding the hydrophobic silica to the spherical fine particles (D), for example, a Henschel mixer which is an ordinary powder mixer or a so-called surface modifier such as a hybridizer is used. You can Incidentally, the external addition is to silica on the surface of the spherical fine particles (D) may be caused to adhere a portion of the silica may be embedded in the spherical nanoparticle (D).

Of course, in the toner of the present invention, if necessary, a negative charge control agent such as a chromium-containing complex salt dye or a negative polarity charge control agent,
Additives such as waxes (release agents) such as polyethylene wax, polypropylene wax, paraffin wax, silicone, and fluorine-based wax are 0.1 to the total weight of the colorant (A) and the binder resin (C). It may contain about 5%. Incidentally, these additives can be added at any step in obtaining the spherical fine particles (D).

There are two-component developing methods and one-component developing methods for developing the electrostatic image formed on the surface of the photoconductor in electrophotography, and the toner of the present invention is a one-component developing method. It can also be used in the development system.

In the two-component developing system, the toner of the present invention is mixed with a carrier to prepare a developer, and the friction thereof causes the toner particles to be charged, and the toner particles adhere to the photosensitive member for development.

In the magnetic brush developing method which is the mainstream of the two-component developing method, the dry toner in which hydrophobic silica is externally added to the spherical fine particles (D) of the binder resin containing the colorant of the present invention is used as a carrier. The toner is charged by friction and forms a magnetic brush, so that only toner adheres to the photoconductor and development is performed.

Any known carrier can be used as the carrier, and examples thereof include magnetic particles (about 20 to 200 μm) such as iron powder and ferrite, and resin-coated carriers such as fluororesin-coated carriers.

On the other hand, there is a magnetic one-component developing system using a magnetic toner mainly composed of a binder resin (C) and magnetic powder, or a non-magnetic one-component developing system comprising only a non-magnetic toner. As a one-component developing method using non-magnetic toner, there is a contact-type non-magnetic one-component developing method in which a developing sleeve carrying a developer is brought into contact with a photosensitive drum having an electrostatic latent image for development.

In the toner of the present invention, the electrostatic latent image formed on the surface of the photosensitive member is formed by passing the toner between the developing sleeve and the charging member pressed against the toner and frictionally charging the toner. It is suitable for a contact type non-magnetic one-component developing method such as developing.

The developing sleeve material may be silicon rubber or a non-magnetic metal material such as stainless steel or aluminum, and the charging member may be flexible material such as stainless steel or rubber.

[0050]

EXAMPLES The present invention will be described more specifically below by showing examples of the present invention. However, the invention is not limited to these examples. All "parts" and "%" are based on weight unless otherwise specified.

Reference Example 1 [Preparation example of resin A capable of having anionic self-water dispersibility] 200 parts of methyl ethyl ketone was placed in a reaction vessel and heated to 80 ° C. Then, the mixture in the proportions shown below was added dropwise over about 2 hours. The reaction was performed under a nitrogen atmosphere.

[0052]   Methacrylic acid 45 parts   Styrene 177 parts   Methyl methacrylate 45 parts   2-Ethylhexyl acrylate 33 parts   "Perbutyl O" (Nippon Oil & Fat Products Co., Ltd.) 3 parts   Methyl ethyl ketone 12 parts

After completion of dropping the mixture, every 4 hours,
0.6 part of "Perbutyl O" was added to the reaction solution, and the reaction was continued at 80 ° C for 24 hours. After the reaction was completed, a solution of a vinyl-based copolymer having a weight average molecular weight of about 45,000, a Tg of about 80 ° C. and an acid value of about 96 was obtained.

Reference Example 2 [Preparation example of resin B capable of having anionic self-water dispersibility] Except that the composition of the dropping mixture was changed as follows, the same procedure as in Reference Example 1 was carried out to obtain a weight average molecular weight of about 50,000 and Tg.
A vinyl copolymer solution having a temperature of about 60 ° C. and an acid value of about 58 was obtained.

[0055]   Acrylic acid 23 parts   180 parts of styrene   Methyl methacrylate 54 parts   2-Ethylhexyl acrylate 43 parts   "Perbutyl O" [Nippon Oil & Fat Products Co., Ltd.] 2.2 parts   Methyl ethyl ketone 12 parts

Reference Example 3 [Preparation Example of Hydrophobic Synthetic Resin] The same procedure as in Reference Example 1 was carried out except that the composition of the dropping mixture was changed as follows. The weight average molecular weight was about 30,000 and the Tg was Tg.
A vinyl copolymer solution having a temperature of about 5 ° C. was obtained.

[0057]   90 parts of styrene   Methyl methacrylate 73 parts   N-Butyl acrylate 137 parts   "Perbutyl O" [Nippon Oil & Fat Products Co., Ltd.] 3.8 parts   Methyl ethyl ketone 12 parts

Reference Example 4 [Preparation Example of Toner Raw Material A] 200 parts of the resin A solution obtained in Reference Example 1 and capable of anionic self-water dispersibility, 100 parts of methyl ethyl ketone, and “Elftex 8” [manufactured by Cabot Corporation] Carbon black] 10 parts, "Eiger motor mill M-25
0 VSE-EXJ "(product of Eiger) for 1 hour.

This mixed solution was placed in a reaction vessel, and acetone 1 was added.
After adding 00 parts and 6 parts of triethylamine (here, the resin A became an anionic self-water dispersible resin),
While stirring, water was added dropwise to this to carry out phase inversion emulsification. The organic solvent was removed by distillation under reduced pressure, triethylamine was neutralized with a 1N aqueous hydrochloric acid solution (here, the anion-type self-water-dispersible resin was Resin A), and filtration / water washing was performed. Next, the wet cake is dried to obtain spherical toner particles having an average particle diameter of about 10 μm (toner base A).
I got).

Reference Example 5 [Preparation Example of Toner Raw Material B] 200 parts of the resin B solution obtained in Reference Example 2, which can be anionic self-water dispersible, 100 parts of methyl ethyl ketone, and 10 parts of “ELFTEX 8”, Mix for 1 hour on an Eiger motor mill. This mixed liquid was placed in a reaction vessel, and 50 parts of isopropyl alcohol and 5 parts of triethylamine were added (here, the resin B became an anion type self-water dispersible resin), and then the same operation as in Reference Example 4 was performed, Spherical toner particles (referred to as toner base B) having an average particle diameter of about 8 μm were obtained.

Reference Example 6 [Preparation Example of Toner Raw Material C] 100 parts of the hydrophobic synthetic resin solution obtained in Reference Example 3, 100 parts of methyl ethyl ketone, and “Elftex 8”
Mix 9 parts in an Eiger motor mill for 1 hour. This mixed solution was placed in a reaction vessel, and 100 parts of the resin A solution obtained in Reference Example 1 that could be anionic self-water dispersible, 50 parts of isopropyl alcohol, and triethylamine.
After adding 5 parts (here, the resin A became an anion-type self-water-dispersible resin), the same operation as in Reference Example 4 was performed, and a spherical core-shell type structure having an average particle diameter of about 8 μm. To obtain toner particles (referred to as toner base material C).

Reference Example 7 [Preparation Example of Toner Raw Material D] 200 parts of the resin B solution obtained in Reference Example 2 which can be anionic self-water dispersible, 100 parts of methyl ethyl ketone,
"Elftex 8" 10 copies, "Bontron S-34"
2.5 parts of [a charge control agent manufactured by Orient Chemical Industry Co., Ltd.] is mixed in an Eiger motor mill for 1 hour. Then, the same operation as in Reference Example 4 is performed, and the average particle size is about 9 μm.
Spherical toner particles of m (referred to as toner base D) were obtained.

First, examples of the negatively chargeable toner for non-magnetic one-component development of the present invention will be described.

Example 1 To 100 parts of the toner base A obtained in Reference Example 4 was added 1 part of hydrophobic silica H2000 (product of Wacker Chemicals Co., Ltd.) having an average primary particle size of 10 nanometers. In addition, parts were mixed using a Henschel mixer to obtain a toner A1 to which silica was externally added.

In a similar manner, hydrophobic silica H2
Toner A2 externally added with 1% of the hydrophobic silica Aerosil R809 (manufactured by Nippon Aerosil Co., Ltd.) having an average primary particle size of 40 nm is obtained.

When these toners A1 and A2 were observed by SEM, it was confirmed that the hydrophobic silica was uniformly attached to the surface of the toner base material A.

Toners A1 and A2 thus obtained
In order to investigate whether or not the toner can be used in a non-magnetic one-component developing method, as a substitute characteristic of the charging property including the polarity of the toner,
A commercially available printer Ricoh LP-1060SP3 remodeling machine (having a silicon rubber developing sleeve and a stainless charging member) is used to charge these toners, and a commercially available surface electrometer is used to charge the toner on the developing sleeve. The charge amount was evaluated by measuring the surface potential of the toner.

The surface potentials of the toners A1 and A2 on the developing sleeve of the modified machine are as shown in FIG. That is, the surface potentials of the toners A1 and A2 to which the hydrophobic silica was externally added were stable at about −26 V with time. FIG. 1 also shows the surface potential of the toner base A.

These toners A1 and A2 are commercially available non-magnetic one-component printers [PC-PR1 manufactured by NEC Corporation].
000E / 4], a sufficient image was obtained.

Comparative Example 1 To 100 parts of the toner base material A obtained in Reference Example 4 was added 1 part of hydrophobic silica Aerosil R809 having an average primary particle diameter of 40 nanometers, and a Henschel mixer was used. To obtain toner A3 to which hydrophobic silica has been externally added. As a result of SEM observation, it was confirmed that silica was uniformly externally added to the surface of the toner base A in this toner.

The surface potential of the toner A3 containing the large-diameter hydrophobic silica on the developing sleeve of the remodeling machine shows a slight minus at the beginning as shown in FIG. It showed a charge and could not be used as a negatively chargeable toner for non-magnetic one-component development.

Example 2 To 100 parts of the toner base material B obtained in Reference Example 5 was added 1 part of hydrophobic silica Aerosil R972 (product of Nippon Aerosil Co., Ltd.) having an average primary particle size of 16 nm. Was added and mixed using a Henschel mixer to obtain a toner B1 to which silica was externally added. Similarly, 0.5 part of hydrophobic silica H2000 was externally added to obtain toner B2.

When these toners B1 and B2 were observed by SEM, it was confirmed that silica was uniformly externally added to the surface of the toner base material B.

As for the surface potential on the developing sleeve of the modified machine, as shown in FIG.
Nos. 2 and 3 all showed a negative charge stability over time, and sufficient images were obtained with the printer manufactured by NEC Corporation. The surface potential of the toner base material B is also shown in FIG.

Example 3 To 100 parts of the toner base material C having the core-shell type structure obtained in Reference Example 6 was added 2 parts of hydrophobic silica H2000, and the mixture was mixed using a Henschel mixer to obtain silica. Toner C1 externally added was obtained.

When this toner was observed by SEM, it was confirmed that silica was uniformly externally added to the surface of the toner base material C.

The surface potential of the toner on the developing sleeve of the modified machine is shown in FIG. In FIG. 3, the surface potential of the toner base material C is also shown. Toner C1 is negative and shows stable chargeability over time.
Sufficient images were obtained with a printer manufactured by the company.

Comparative Example 2 2 parts of Aerosil R809 were added to 100 parts of the toner base material C having the core-shell type structure obtained in Reference Example 6 and mixed using a Henschel mixer to remove silica particles. The added toner C2 was obtained.

When this toner was observed by SEM, it was confirmed that silica was uniformly externally added to the surface of the toner base material C.

However, as shown in FIG. 3, the surface potential on the developing sleeve of the modified machine shows a slight negative value at first, but becomes a different polarity with the lapse of time, and the negative chargeability for non-magnetic one-component developing is shown. It could not be used as a toner.

(Example 4) To 100 parts of toner base material D containing the charge control agent obtained in Reference Example 7, 1.5 parts of hydrophobic silica H2000 was added and mixed using a Henschel mixer. Then, a toner D1 to which silica was externally added was obtained.

When this toner was observed by SEM, it was confirmed that silica was uniformly externally added to the surface of toner base material D.

Regarding the surface potential on the developing sleeve of the modified machine, as shown in FIG. 4, the toner D1 showed negative and stable charging property. FIG. 4 also shows the surface potential of the toner base material D. This toner D1
, A sufficient image was obtained with the printer manufactured by NEC Corporation.

(Comparative Example 3) 100 parts of the toner base material D containing the charge control agent obtained in Reference Example 7 was mixed with 100 parts of Aerosil RX-50 (Japan Aerosil Co., Ltd.) having an average primary particle size of about 40 nm. ) Product] was added and mixed using a Henschel mixer to obtain a toner D2 externally added with silica.

When this toner was observed by SEM, it was confirmed that silica was externally uniformly added to the surface of the toner base material C.

The surface potential of this toner D2 on the developing sleeve of the above-mentioned modified machine initially showed a negative value as shown in FIG. 4, but changed to zero with the lapse of time.

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

EFFECTS OF THE INVENTION By externally adding hydrophobic silica having an average primary particle diameter of 5 to 30 nanometers to a toner composed of spherical fine particles produced by a phase inversion emulsification method, chargeability is improved in the negative direction. It has a particularly remarkable effect of being able to do it.

[0094] Non-magnetic one-component developing system odor Te, can in particular greatly improved chargeability in a negative direction, yet achieves exceptional remarkable effect of expressing sufficient charging performance can be put to practical use.

[Brief description of drawings]

FIG. 1 is a diagram showing changes with time of surface potentials of various toners for non-magnetic one-component development obtained by using a toner raw material A obtained in Reference Example 4 by a non-magnetic one-component development printer.

FIG. 2 is a diagram showing changes with time in surface potential of various toners obtained by using a toner base material B obtained in Reference Example 5 by a non-magnetic one-component developing printer.

FIG. 3 is a diagram showing changes with time of surface potentials of various toners for non-magnetic one-component development obtained by using the toner base material C obtained in Reference Example 6 by a non-magnetic one-component development printer.

FIG. 4 is a diagram showing changes with time in surface potential of various toners obtained by using a toner base material D obtained in Reference Example 7 by a non-magnetic one-component developing printer.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-10269 (JP, A) JP-A-6-167827 (JP, A) JP-A-5-333583 (JP, A) JP-A-5- 66600 (JP, A) JP-A-4-177361 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (2)

(57) [Claims] 1. Spherical fine particles (D) in which a colorant (A) contains a binder resin (C) containing at least 25% by weight or more of a resin (B) capable of becoming anionic self-water dispersible by neutralization. The average particle diameter of primary particles is 5 to 30 nanometers (E), or 5 to 30 nanometers of hydrophobic silica (E) and 30 nanometers or more.
Electrophotographic non-magnetic material in which both hydrophobic silica (F) of nanometer or less is externally added in an amount of 0.1 to 3.0 parts by weight per 100 parts by weight of the total of the colorant (A) and the binder resin (C). Negative polarity toner for one-component development. 2. The organic solvent solution of the binder resin (C), wherein the spherical fine particles (D) contain at least 25% by weight of the anionic self-water dispersible resin (B) in which the colorant (A) is dispersed. After adding a base, and then adding water or adding a base to the organic solvent solution, and then performing phase inversion emulsification by adding to water, it is obtained through the steps of solvent removal, neutralization, dehydration, and drying. claim 1 Symbol placement electrophotographic method for nonmagnetic monocomponent development negative polarity toner is spherical fine particles.