JPH0876421A - Toner for binary system developer - Google Patents

Abstract

PURPOSE: To provide a toner that contains no electrostatic charge control agent being mainly attributable to a spent at time of copying, which is sufficient enough in electrifiability, no scattering at time of copying, also adequate enough in transfer efficiency, thereby making the required density copied image stably securable for hours, and further hard to be stuck to a sensitizer as well as to be high in smoothness of a surface of the copied image to be contained and thus a lustrous copied image is made so as to be securable. CONSTITUTION: This is a toner for a binary system developer inclusive of toner grains containing fixing resin and magnetic powder dispersed in this resin. This fixing resin in the toner grains consists of a composition containing a kind of resin with an anionic polar group, and the magnetic powder is contained in the toner grains at the specified rate. Toner grain's volume reference mean grain size ranges from 5 to 15μm, and a spacer grain ranging from 0. 05 to 1.0μm in this volume reference mean grain size is stuck to the toner grain surface and, in turn, metallic salt stearate is stuck to the toner grain surface to which the spacer grain is stuck.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-component developer toner, and more specifically, it has a good transfer efficiency and can produce a copy image having a desired density for a long time even though it does not contain a charge control agent. The present invention relates to a toner for a two-component developer, which is a long-life toner obtained and is preferably used in an electrophotographic image forming apparatus such as an electrostatic copying machine or a laser beam printer.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a two-component developer is used as one of the developers for developing an electrostatic latent image on a photoconductor. This two-component developer contains a toner containing a coloring agent such as carbon black and a fixing resin, and a magnetic carrier containing iron powder, ferrite particles and the like.

During development, the toner and carrier are mixed to charge the toner to a predetermined polarity, and then the mixture is conveyed to the photoconductor in the form of a magnetic brush. The photoconductor is rubbed by this magnetic brush, and toner adheres to the electrostatic latent image on the surface of the photoconductor. A charge control agent is generally contained in the toner particles in order to make the amount of toner adhered constant and give a predetermined charge amount to the toner in order to provide a stable image. Negative charge control agents such as metal-containing complex dyes containing a metal such as chromium (eg, azo dyes) and oxycarboxylic acid metal complexes (eg, salicylic acid metal complexes) are used for negatively chargeable toners. No. 3-67268), and positively chargeable toners use oil-soluble dyes such as nigrosine and positive charge control agents such as amine-based control agents (JP-A-56-56).
106249).

The charge control agents that have been conventionally used are often compounds containing heavy metals such as chromium-containing complexes.
When using these compounds, compounds that have passed various toxicity tests and safety tests are selected from the viewpoint of environmental safety. However, even if there is no problem in safety as a compound or in the form of being contained in the toner,
It would be more desirable to avoid the use of charge control agents containing these heavy metals. Furthermore, since the charge control agent has a higher unit price than the fixing resin and the colorant such as carbon black, which are the materials constituting the toner, the charge control agent is pushing up the unit price of the toner regardless of the content rate of about several percent. Therefore, there is a demand for the development of a toner containing no charge control agent containing such a heavy metal.

Further, in the conventional toner, the toner component adheres to the particle surface of the carrier due to long-term use, so that the charged state of the particle surface of the carrier is similar to the charged state of the toner particle surface. come. As a result, there is a drawback that the toner is scattered and the transfer efficiency is lowered.

[0006]

DISCLOSURE OF THE INVENTION The present invention is to solve the above-mentioned conventional problems, and an object thereof is to:
It is an object of the present invention to provide a toner for a two-component developer in which the toner does not scatter and the image quality is excellent because the toner has good charging performance even though it does not contain any charge control agent. Another object of the present invention is to provide a toner for two-component type developer, which does not cause spent even during long-term use, and as a result, can maintain good image quality and have stable transfer efficiency.

[0007]

SUMMARY OF THE INVENTION The present invention is a two-component developer toner containing a fixing resin and magnetic powder dispersed in the fixing resin; the fixing resin is an anionic polar group. The magnetic powder is contained in the toner particles in a ratio of 0.1 to 5 parts by weight with respect to 100 parts by weight of the fixing resin; and a volume-based average of the toner particles. The particle size is 5 to 15 μm; the volume-based average particle size is 0.05 to 1.0 μm on the surface of the toner particles.
m spacer particles are attached; and metal stearate is attached to the surface of the toner particles to which the spacer particles are attached; thus, the above object is achieved.

In a preferred embodiment, the extraction liquid when the toner is extracted with methanol is 280 to 350.
has substantially no absorption peak in the nm region, and 400
The absorbance in the region from to 700 nm is substantially zero.

In a preferred embodiment, the magnetic powder is 0.5 to 3 with respect to 100 parts by weight of the fixing resin.
It is contained in a ratio of parts by weight.

In a preferred embodiment, the metal salt of stearic acid is at least one selected from the group consisting of zinc stearate and magnesium stearate.

In a preferred embodiment, the metal stearate is selectively attached to the surface of the spacer particles.

[0012]

The two-component developer toner of the present invention does not contain any charge control agent such as an azo dye or a metal oxycarboxylic acid complex. Therefore, as will be described later, the spent due to the charge control agent is not generated, so that the high quality image can be copied for a long time. Since this toner does not contain any charge control agent, it is possible to obtain such a charge control agent from the toner by any chemical or physical means.
That is, no dye-based compound is detected. For example, these compounds are not detected by the chemical reaction in the toner of the present invention. Alternatively, no absorption peaks due to these compounds are detected in the organic solvent extract of the toner of the present invention. For example, when the toner of the present invention is extracted with an organic solvent, for example, methanol, the extract liquid is 280-35.
It has substantially no absorption peak in the region of 0 nm and is 40
The absorbance at wavelengths in the range 0-700 nm is substantially zero. Here, having substantially no absorption peak means that
In an extract obtained by extracting 0.1 g of toner with 50 ml of methanol, an absorption peak is not detected at all, or even if it is detected, the absorbance at the peak position is 0.05 or less. Similarly, that the absorbance is substantially zero means that the absorbance of the extract obtained by extracting 0.1 g of the toner with 50 ml of methanol is not more than 0.05.

In the two-component developer toner of the present invention, the instability of the charge amount due to the absence of the charge control agent is compensated for by the following matters. Firstly, the resin having an anionic polar group is used as the fixing resin in the toner particles, and secondly, the magnetic powder is contained in the toner particles in a predetermined ratio. In the present invention, spacer particles having a predetermined particle diameter are attached to the surface of the toner particles to improve the transfer efficiency from the photoconductor to the transfer paper. In the present invention, metal stearate is further adhered to the surface of the toner particles to which the spacer particles are adhered at a predetermined ratio. Here, the surface of the toner particles to which the spacer particles are attached refers to the surface of the toner particles themselves and / or the surface of the spacer particles attached to the toner particles. As a result, the releasability of the toner from the photoconductor is improved, and the toner is less likely to adhere to the photoconductor. By using the stearic acid metal salt, the fixability of the transferred image is enhanced, the smoothness of the surface of the obtained copy image is also enhanced, and a glossy copy image is obtained.

The above will be described in detail below.

20% of the methanol extract of the toner of the present invention
The absorbance curve at 0 to 700 nm is shown in FIG. As shown in this curve, this extract does not have any peaks attributed to each charge control agent. That is, 280-35
It has substantially no absorption peak in the region of 0 nm, and 40
The absorbance in the region of 0 to 700 nm is substantially zero. On the other hand, the absorbance curve of the methanol extract of the toner containing the azo chromium complex salt dye as the charge control agent has a peak in the region of 400 to 700 nm, particularly 550 to 570 nm (FIG. 2), and salicylic acid. The absorbance curve of the methanol extract of the toner containing the metal complex as the charge control agent has a peak in the region of 280 to 350 nm (FIG. 3).

The absorption due to the charge control agent is observed in the methanol extract of the toner containing the charge control agent, because the charge control agent is present at a considerably high concentration on the surface of the toner particles. is there.

The carrier of the developer whose chargeability of the carrier becomes insufficient due to generation of spent is extracted with methanol,
When the absorbance at 400 to 700 nm is examined, a peak due to the charge control agent is observed in that region. For example, a toner containing an azo chromium complex salt dye, the absorbance curve of which is shown in FIG. 2, is used for a long time,
FIG. 4 shows the absorbance curve of the methanol extract of the carrier when the spent was generated. In FIG. 4, a peak is recognized at the same position as that of the charge control agent in FIG. In the past, it was thought that the spent was caused by the resin for fixing the toner adhering to the particle surface of the carrier to form a resin film, but due to the above fact, one of the main causes of the spent generation is charging. It was found that the control agent was transferred from the toner particles to the surface of the carrier particles.

The inventors further conducted the following experiment to investigate the relationship between the charge control agent and the spent. First, a toner having toner particles containing an azo chromium complex salt dye at a ratio of 1.5 wt% as a charge control agent was mixed with a carrier to obtain a developer. FIG. 5 shows the relationship between the elapsed time when the operation of mixing and stirring the toner of the developer and the carrier is continued and the weight of the deposit adhered to the particle surface of the carrier by the spent. The weight of the deposit is a percentage of the total weight of the carrier having the deposit and is shown in FIG. 5 as the percentage of spent. Further, FIG. 6 shows the relationship between the elapsed time and the toner charge amount. Further, the same measurement was performed for the developer containing the toner having the toner particles not containing the charge control agent and the carrier. The results are also shown in Figure 5.
And 6 are shown. In FIGS. 5 and 6, the black circle plots show the measured values of the toner containing the charge control agent, and the white circle plots show the measured values of the toner without the charge control agent. From FIGS. 5 and 6, it can be seen that the toner containing the charge control agent has a larger amount of deposits on the particle surface of the carrier due to the spent and the degree of decrease in the charge amount is larger than that of the toner containing no charge control agent.

The weight of the toner component adhering to the surface of the particles of the carrier was measured with the spent, and the abscissa represents the weight (shown as the spent amount), and the ordinate represents the amount of the charge control agent in the toner component. The graph taken is shown in FIG. The dotted line shows the amount of the charge control agent when it is assumed that the toner component attached by the spent is the same as the component forming the toner particles. From FIG. 7, it can be seen that a large amount of the charge control agent is deposited and adheres to the particle surface of the carrier in the initial stage of using the developer. In FIG. 7, the reason why the measured value approaches the calculated value indicated by the dotted line with the increase in the amount of spent is that this is an experimental result in a closed system without toner replenishment. If there is a replacement, the difference between the two will be further widened.

Further, in order to investigate the relationship between the components constituting the toner particles and the spent toner, the inventors mixed a carrier with a charge control agent, a fixing resin, carbon black as a colorant, and a wax. -The weight of the deposits on the surface of the particles of the carrier produced by the passage of time with stirring was measured. FIG. 8 shows the result. In FIG.
The white circles show the results when the test was conducted using the charge control agent, the black circles the carbon black, the squares the fixing resin, and the triangles the wax. It can be seen from FIG. 8 that the charge control agent is most likely to cause the spent to adhere to the surface of the particles of the carrier.

From the above facts, the charging failure due to the spent of the conventional two-component magnetic developer is explained as follows. First, as shown in the upper part of FIG. 9, in the initial stage of use of the developer, the carrier particles 1 are positively charged and the toner 2 is negatively charged, and the toner exists as the negative polarity toner 21. When this developer is used, the toner component containing the charge control agent as a main component in the toner particles adheres to the surface of the carrier particles 1. Since the deposit 201 formed by this spent is negatively charged, the toner having a positive charge with respect to the deposit 201, that is, the opposite polarity toner 22 is formed. This reverse polarity toner 22
Are formed on the surface of the particles 1 of the carrier, toner scattering occurs, and the transfer efficiency decreases.

Thus, the charge control agent, as described above,
Since it may contain a heavy metal, it is preferable not to contain it. Further, as described above, it becomes a main cause of spent, causing toner scattering, lowering of transfer efficiency, and the like. Contains no agents.

The instability of the charge amount due to not containing the charge control agent, mainly the lack of the charge amount, is due to the use of the fixing resin having an anionic polar group in the toner as described above. Will be supplemented. Since the fixing resin itself is provided with a negative charge by the anionic polar group, the insufficient charge amount of the toner particles is compensated. Since this polar group exists by binding to the skeleton of the resin itself, it does not migrate to the particle surface of the carrier like a charge control agent and cause spent. However, conversely, the chargeability near the surface of the toner particles is
Since it is not so large, the coupling between the toner particles and the carrier particles by the Coulomb force in the magnetic brush during development is still insufficient. Therefore, when high-speed copying is performed, the bondability between the carrier particles and the particles is weak, and the toner scattering is not sufficiently suppressed. There is a drawback that the inside of the copying machine is contaminated by the scattering of the toner and so-called fog occurs in the image of the copy.

In the present invention, as the second requirement as described above, the magnetic powder is contained in the toner particles in a predetermined ratio, that is, in a ratio of 0.1 to 5 parts by weight with respect to 100 parts by weight of the fixing resin. Incorporation is employed to make up for the shortage of the charge amount of the toner particles. Since the magnetic powder is contained in the toner particles, a magnetic attractive force is generated between the toner particles and the carrier particles. In this way, in addition to the Coulomb force between the toner particles and the particles of the carrier, a magnetic attraction force is generated, so that toner scattering is prevented. Generally, the smaller the amount of charge per toner particle,
Since the number of toner particles attached to a given electrostatic latent image is increased, the apparent development sensitivity is increased.

The content of the magnetic powder in the toner particles is
As described above, the amount is 0.1 to 5 parts by weight per fixing resin. When the content of the magnetic powder is less than 0.1 part by weight, the charge amount of the toner is insufficient as described above, the particles are not sufficiently bonded to the carrier particles, and the toner is easily scattered. That is, there is a drawback that so-called fog occurs in the image of the copy. When the content of the magnetic powder exceeds 5 parts by weight, the binding force between the carrier particles and the toner particles becomes too large, so that the toner does not adhere sufficiently to the electrostatic latent image,
As a result, the image density becomes low.

To date, attempts have been made to incorporate (internally add) magnetic powder into toner particles for the purpose of improving the resolution of images. For example, JP-A-56-1062
No. 49 discloses toner particles containing 10% by weight of ferrite, and JP-A No. 59-162563 discloses toner particles containing 5 to 35% by weight of magnetic fine powder. . However, in either case, the image density of the obtained copy is low because the amount of the magnetic powder is excessive. Japanese Patent Application Laid-Open No. 3-67268 discloses a toner to which magnetic powder is externally added at a ratio of 0.05 to 2% by weight. However, since the magnetic powder is not internally added to the toner particles, it tends to be nonuniformly attached to the surface of the toner particles, and the magnetic attraction between the toner particles and the carrier particles is insufficient. In any of the above-mentioned conventional techniques, since the toner contains the charge control agent, problems such as spent may occur.

In the present invention, in order to further improve the transfer efficiency of the toner image, the toner particles have a particle size of 0.05.
Spacer particles of ˜1.0 μm are attached. The spacer particles can act as a fluidity improver for the toner particles and form a gap between the photoconductor and the toner particles when the toner adheres to the surface of the photoconductor. Therefore, even if the charge amount of the toner becomes high due to copying for a long time, the toner can be easily transferred from the surface of the photoconductor to the transfer paper, so that the transfer efficiency becomes high. When the spacer particles are particles of magnetic powder, the binding ability between the toner particles and the particles of the carrier is further stabilized, so that toner scattering and fog can be further reduced.

As a conventional fluidity improving agent for toner, fine particles having a particle diameter of about 0.015 μm are used as an external additive. Such particles form a sufficient gap between the photoreceptor and the toner particles. Therefore, it does not function as the spacer particles for the above purpose.

In the present invention, as described above, the metal stearate is further attached to the surfaces of the toner particles and / or the spacer particles, so that the releasability between the toner and the surface of the photoconductor is enhanced. Therefore, the toner hardly adheres to the surface of the photoconductor. Particularly, when the metal stearate is selectively adhered only to the surface of the spacer particles, the metal stearate comes into contact with the surface of the photoconductor effectively, so that the toner and the spacer particles are prevented from adhering to these surfaces. It can be prevented more effectively. In addition, since the melt viscosity of the toner is reduced by using the metal stearate, the penetration of the toner into the transfer paper is improved in the heat fixing by the heat roll, and the fixing property of the image is improved. Further, since the melting temperature of the metal stearate is lower than the melting temperature of the fixing resin, when the transfer image is fixed, the smoothness of the image surface is improved and a glossy copy image is obtained. Furthermore, by adhering the metal stearate to the surface of the toner particles, the resistance of the toner can be appropriately reduced, and a high density copy image can be obtained.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The preferable modes of the present invention will be described below. Hereinafter, in the present specification, "lower alkyl group"
Is an alkyl group having 1 to 5 carbon atoms.

(Fixing Resin) The fixing resin contained in the toner particles of the two-component developer toner of the present invention is a composition containing a resin having an anionic polar group. Such a resin is obtained by polymerizing a monomer containing a monomer having an anionic polar group, and the obtained resin may be a homopolymer or a copolymer.

The resin used as the fixing resin is preferably a copolymer of a monomer having an anionic polar group and another monomer. For example, it may be a random copolymer, a block copolymer or a graft copolymer of a monomer having an anionic group and another monomer.

Examples of the monomer having an anionic polar group include a monomer having a carboxylic acid group, a sulfonic acid group or a phosphonic acid group, and a monomer having a carboxylic acid group is particularly preferable. As the monomer having a carboxylic acid group, an ethylenically unsaturated carboxylic acid is used, which includes acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, etc., and carboxylic acid such as maleic anhydride. Monomers capable of forming groups or lower alkyl half esters of dicarboxylic acids such as maleic acid and fumaric acid can also be used. Examples of the monomer having a sulfonic acid group include styrenesulfonic acid, 2-acrylamido-
2-methyl propane sulfonic acid etc. are mentioned. Examples of the monomer having a phosphonic acid group include 2-acid phosphoxypropyl methacrylate, 2-acid phosphoxyethyl methacrylate, and 3-chloro-2-acid phosphoxypropyl methacrylate.

These anionic polar group-containing monomers are
It may be a free acid, an alkali metal such as sodium or potassium, an alkaline earth metal such as calcium or magnesium, or a salt such as zinc.

The above-mentioned monomer having an anionic polar group and other monomer to be polymerized as necessary are selected so that the resulting polymer has the fixability and chargeability required for the toner. , A combination of one or more monomers having an ethylenically unsaturated bond is used. Examples of such monomers include acrylic ester monomers, monovinyl aromatic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers. and so on.

The acrylic ester-based monomer is represented by the following general formula (I):

[0037]

Embedded image

Here, R ¹ is a hydrogen atom or a lower alkyl group, and R ² is a hydrocarbon group having 11 or less carbon atoms or a hydroxyalkyl group having 11 or less carbon atoms.

Examples of such a monomer include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate,
Phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, β-
Examples thereof include ethyl hydroxyacrylate, γ-hydroxyacrylate propyl, δ-hydroxyacrylate and β-hydroxymethacrylate.

Monovinyl aromatic monomers are represented by the following general formula (II):

[0041]

Embedded image

Here, R ³ is a hydrogen atom, a lower alkyl group or a halogen atom, R ⁴ is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group or the like, and Φ is a phenylene group. Is.

Examples of such a monomer include styrene and α
-Methylstyrene, vinyltoluene, α-chlorostyrene, o-, m-, or p-chlorostyrene, p-ethylstyrene and the like.

The vinyl ester monomer is represented by the following general formula (III):

[0045]

[Chemical 3]

Here, R ⁵ is a hydrogen atom or a lower alkyl group.

As such a monomer, vinyl formate,
Examples include vinyl acetate and vinyl propionate.

The vinyl ether type monomer is represented by the following general formula (IV):

[0049]

[Chemical 4]

Here, R ⁶ is a monovalent hydrocarbon group having 11 or less carbon atoms.

Examples of such a monomer include vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether and vinyl cyclohexyl ether.

The diolefin monomer is represented by the following general formula (V):

[0053]

[Chemical 5]

Here, R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom, a lower alkyl group or a halogen atom.

As such a monomer, butadiene,
Examples include isoprene and chloroprene.

The mono-olefinic monomer is represented by the following general formula (VI):

[0057]

[Chemical 6]

Here, R ¹⁰ and R ¹¹ are each independently a hydrogen atom or a lower alkyl group.

Examples of such a monomer include ethylene, propylene, isobutylene, butene-1, pentene-1,
4-methylpentene-1 and the like.

Specific examples of the resin having an anionic polar group which is a (co) polymer obtained by polymerizing the above monomers include styrene-acrylic acid copolymer, styrene-maleic acid copolymer, and ionomer. Resin etc. further,
A polyester resin having an anionic polar group can be used. Such a resin has an acid value of 2 to 3 when the anionic polar group is present in the form of a free acid.
It is desirable to have an anionic polar group in a ratio of 0, preferably 5 to 15. When part or all of the anionic polar group is neutralized, it is preferable to have the anionic polar group in such a proportion that it has the above-mentioned acid value when it exists in the form of a free acid. When the acid value of the resin, that is, the concentration of the anionic polar group, is lower than the above range, the chargeability of the toner is insufficient, and when it is higher than the above range, the toner has hygroscopicity, which is preferable. Absent. A suitable fixing resin contains the above-mentioned monomer having an anionic polar group and at least one kind of the acrylic monomer of the formula (I) as an essential component, and if necessary, the compound of the formula (II ), A copolymer containing the monomer of the formula (VI) as an optional component is used. Each of the above monomers is
One kind or a combination of two or more kinds may be used for preparing the above resin.

As the fixing resin used in the present invention, a resin composition containing the above resin is used.
In addition to the above resin, a polymer having no anionic polar group may be contained. In that case, the content ratio of the anionic polar group in the entire composition is preferably in the above range.

(Magnetic Powder) As the magnetic powder contained (internally added) in the toner particles, any of the magnetic powders conventionally used for one-component magnetic toners can be used. Examples of the material of the magnetic powder include ferrosoferric oxide (F
e ₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe ₂ O ₄ ), iron oxide yttrim (Y ₃ Fe)
₅ O ₁₂ ), iron cadmium oxide (CdFe ₂ O ₄ ), gadolinium iron oxide (Gd ₃ Fe ₅ O ₁₂ ), iron oxide copper (CuFe ₂
O ₄ ), lead iron oxide (PbFe ₁₂ O ₁₉ ), iron nickel oxide (NiFe ₂ O ₄ ), iron neodymium oxide (NdFe)
O ₃ ), iron oxide barium (BaFe ₁₂ O ₁₉ ), iron oxide magnesium (MgFe ₂ O ₄ ), iron manganese oxide (MnF
e ₂ O ₄ ), lanthanum iron oxide (LaFeO ₃ ), iron (F
e), cobalt (Co), nickel (Ni), etc. may be used. A particularly preferred magnetic powder is finely particulate iron trioxide (magnetite). Suitable magnetite has a regular octahedron shape and a particle size of 0.05 to 1.0 μm. The magnetite particles may be surface-treated with a silane coupling agent, a titanium coupling agent, or the like. The particle size of the magnetic powder contained in the toner particles is generally 1.0 μm.
m or less, preferably 0.05 to 1.0 μm.

The content of the magnetic powder in the toner particles is
0.1 to 5 parts by weight, preferably 0.5 to 4 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the fixing resin.
3 parts by weight. If the amount of the magnetic powder is too small, as described above, the toner may scatter during development, or the transfer efficiency may decrease.

(Compounding Agent in Toner Particles) The toner particles are
As described above, the fixing resin and the magnetic powder are contained as essential components, and if necessary, a compounding agent that can be usually compounded in the toner can be contained.

Examples of the compounding agent include a colorant and a release agent.

As the colorant, for example, the following pigments can be used.

Black pigments Carbon black, acetylene black, lamp black, aniline black.

Body pigments Barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

The above-mentioned pigment is usually contained in the toner particles in an amount of 2 to 20 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of the fixing resin.

As the release agent, various waxes and low molecular weight olefin resins are used. As the olefin resin, polypropylene, polyethylene, propylene-ethylene copolymer and the like can be used, but polypropylene is particularly preferable.

(Preparation of Toner Particles) The toner particles used in the toner of the present invention can be prepared by a general method for producing toner particles, for example, a pulverizing and classifying method, a melt granulating method, a spray granulating method and a polymerization method. It can be produced and is usually produced by a pulverizing and classifying method.

For example, the components for forming the toner particles are premixed with a mixer such as a Henschel mixer, then kneaded with a kneading device such as a twin-screw extruder, cooled, and then pulverized. The toner particles are classified to obtain toner particles. The toner particles have a volume-based average particle diameter (median diameter by Coulter counter) of 5 to 15 μm, and preferably in the range of 7 to 12 μm.

(Spacer Particles) In the toner of the present invention, spacer particles are externally added and adhere to the surfaces of the toner particles.

The spacer particles have a volume-based average particle diameter of 0.05 to 1.0 μm, preferably 0.07 to
Either 0.5 μm organic or inorganic inert particles can be used. As a material for such inert particles,
Silica, alumina, titanium oxide, zinc oxide, barium sulfate, magnesium carbonate, acrylic resin, styrene resin,
Examples thereof include acrylic-styrene copolymers and magnetic materials. The spacer particles can function as a fluidity improver and also have a function of enhancing transfer efficiency as described above.

The spacer particles are 10% by weight or less, preferably 0.1 to 10% by weight, based on the total weight of the toner.
More preferably, it is contained in an amount of 0.1 to 5% by weight.
If it is excessive, the density of the copied image will be insufficient.

(Stearic acid metal salt) Examples of the metal stearate salt externally added to the toner particles to which the spacer particles are attached include zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, chromium stearate and stearin. Mercury acid,
Cerium stearate, ferric stearate, sodium stearate, lead stearate, barium stearate and the like can be mentioned, and these can be used alone or as a mixture of two or more kinds. Among the above metal stearates, at least one selected from the group consisting of zinc stearate and magnesium stearate is preferable, and zinc stearate alone is particularly preferable. Instead of the metal salt of stearic acid, stearic acid amide may be used.

The metal salt of stearic acid is 0.001 to 3% by weight, preferably 0.003% by weight based on the total weight of the toner.
The spacer particles may be externally added to the attached toner particles in an amount of ˜1 wt%, and more preferably 0.005 to 0.2 wt%. The metal stearate may be attached to the surfaces of the toner particles and the spacer particles, respectively, but is preferably attached selectively to the surfaces of the spacer particles attached to the toner particles. Here, selectively adhering to the surfaces of the spacer particles means that the metal stearate is not substantially adhered to the surfaces of the toner particles, but is adhered only to the spacer surfaces. To selectively attach the metal stearate to the spacer particles, the metal stearate and the spacer particles may be mixed in advance, and this mixture may be added to the toner particles, as described later.

(Other External Additives) As described above, the toner of the present invention requires that the spacer particles and the metal stearate are adhered to the surface of the toner particles, and further, it is necessary. In accordance with the above, a fluidity improver other than the metal stearate having a particle diameter smaller than the spacer particles such as hydrophobic vapor grown silica particles is attached to the surface of the toner particles to further improve the fluidity of the toner. be able to.

The particle size of the fluidity improving agent such as silica particles is usually about 0.015 μm in the primary particle size, and the total weight of the toner, that is, the toner particles and the external additive (spacer particles, metal stearate) is used. It may be externally added in an amount of 0.1 to 2.0% by weight based on the total weight of the salt and the fluidity improver.

(Preparation of Toner) To the toner particles prepared as described above, the spacer particles, the metal stearate and, if necessary, the fluidity improver can be externally added by, for example, spacer particles, stearin. The acid metal salt and, if necessary, the fluidity improver may be sufficiently mixed, and this mixture may be added to the toner particles and sufficiently crushed. As a result, the spacer particles are uniformly attached to the surface of the toner particles, and the metal stearate is further attached to the surfaces of the toner particles and the spacer particles, so that the toner having the metal stearate attached to the toner surface and the spacer particles is obtained. To be

In addition, the above-mentioned spacer particles and metal stearate are thoroughly mixed in advance, the metal stearate is adhered to the surface of the spacer particles, the spacer particles having the metal stearate adhering to the surface, and If necessary, a fluidity improver is thoroughly mixed, and this mixture is added to toner particles and sufficiently crushed. As a result, it is possible to obtain a toner in which the spacer particles are uniformly attached to the surface of the toner and the metal stearate is selectively attached to the surface of the spacer particles.

In addition to the above, the toner particles and the metal stearate are thoroughly mixed in advance to adhere the metal stearate to the surface of the toner particles, and the metal stearate is attached to the surface of the toner particles. , Spacer particles and optionally a fluidity improver are further deposited. As a result, a toner is obtained in which the metal stearate is attached only to the surfaces of the toner particles, and the metal stearate is not attached to the surfaces of the spacer particles.

Here, the term "adhesion" refers to either the state of being carried in contact with the surface of a particle or the state of being fixed in a state of being partially driven from the surface of the particle.

In this way, the toner of the present invention is obtained.

(Preparation of Developer) The toner of the present invention is
It is mixed with a magnetic carrier to give a two-component developer.

As the magnetic carrier, a ferrite type magnetic carrier is preferably used. Preferably, in addition to Fe, soft ferrite containing at least one kind of metal component selected from the group consisting of Cu, Mg, Mn and Ni, preferably two or more kinds, for example, sintered ferrite of copper-zinc-magnesium ferrite. Particles consisting of are used, especially spherical particles. The surface of the particles of the magnetic carrier may not be coated, but in general, it is preferably coated with silicone resin, fluorine resin, epoxy resin, amino resin, urethane resin or the like. The particle size of the magnetic carrier particles is 30 to 200 μm, and particularly 50 to 150 μm.
It is preferably in the range of μm. The saturation magnetization of the carrier is preferably 30 to 70 emu / g, particularly 45 to 65 emu / g.

The mixing ratio of the magnetic carrier and the toner is generally 98: 2 to 90:10 by weight, particularly 97: 3 to 9 by weight.
A weight ratio of 4: 6 is preferred.

By using the two-component type developer containing the toner of the present invention, copying can be carried out by a general electrostatographic copying method. For example, after uniformly charging the photoconductive layer on the photoreceptor, imagewise exposure is performed to form an electrostatic latent image, and then a magnetic brush of a two-component magnetic developer is brought into contact with the photoreceptor to form the electrostatic latent image. Can be easily developed. The toner image formed by the development is transferred onto a transfer paper to form a transfer image, and the transfer image is fused and pressure-bonded with a heat roll to fix the image.

[0089]

EXAMPLES The present invention will be described with reference to examples.

(Example 1)

[0091]

[Table 1]

The above components were melt-kneaded by a twin-screw extruder, then the kneaded product was ground by a jet mill and classified by an air classifier to obtain toner particles having an average particle size of 10.0 μm.

Hydrophobic silica fine particles having an average particle diameter of 0.015 μm are added (externally added) to the toner particles at a ratio of 0.3 part by weight to 100 parts by weight of the toner particles, and a spacer is added. The average particle size is 0.15
μm of magnesium carbonate was added (externally added) in a ratio of 0.5 part by weight to 100 parts by weight of the toner particles, and zinc stearate as a metal stearate was added in an amount of 0.05 parts by weight with respect to 100 parts by weight of the toner particles. Parts by weight (externally added) and mixed in a Henschel mixer for 2 minutes,
Toner was obtained.

Example 2 First, the average particle size is 0.1
10 parts by weight of 5 μm magnesium carbonate and 1 part by weight of zinc stearate as a metal stearate were mixed with a Henschel mixer for 10 minutes.

This mixture was added to the toner particles obtained in Example 1 in a ratio of 0.55 parts by weight to 100 parts by weight of the toner particles (that is, 0.5 parts by weight of magnesium carbonate and 0.1 parts by weight of zinc stearate). (Weight ratio of 05 parts by weight) (external addition), and the average particle size as a fluidity improver is 0.0
Hydrophobic silica fine particles of 15 μm were added (externally added) at a ratio of 0.3 part by weight to 100 parts by weight of the toner particles, and mixed by a Henschel mixer for 2 minutes to obtain a toner.

(Example 3) Instead of 5 parts by weight of zinc stearate mixed with 50 parts by weight of magnesium carbonate, 2 parts by weight of magnesium stearate was mixed, that is, this mixture was prepared as a toner obtained in Example 1. 0.52 parts by weight relative to 100 parts by weight of toner particles (that is, 0.5 parts by weight of magnesium carbonate and 0.02 parts by weight of magnesium stearate) (external addition) A toner was obtained in the same manner as in Example 2 except for the above.

Comparative Example 1 A toner was obtained in the same manner as in Example 1 except that zinc stearate was not added (externally added).

[Evaluation of Toner] To the toners obtained in Examples and Comparative Examples, a ferrite carrier having an average particle diameter of 100 μm was added and uniformly mixed to obtain a toner concentration of 3.
A 5% by weight two-component developer was obtained. Next, the developer was evaluated for the following items. What was used for the test was an electronic copying machine (trade name "DC-468" manufactured by Sanda Kogyo Co., Ltd.
5)) modified machine (a modified copying machine for easily sampling the evaluation sample).

(A) Image Density (ID) 50,000 copies were made using a character original having a black area ratio of 8%. The density of the black solid portion in the copied image was measured every 5,000 sheets using a reflection densitometer (model number "TC-6D" manufactured by Tokyo Denshoku Co., Ltd.), and the average value was taken as the image density (ID). . Here, the document used for sampling every 5,000 sheets is a document in which the area ratio of the black portion including the black solid portion is 15%. Table 2 shows the evaluation results.

(B) Fog Density (FD) 50,000 copies were made using a character original having a black area ratio of 8%. The density of the non-image area in the copied image was measured every 5,000 sheets using a reflection densitometer (model number "TC-6D" manufactured by Tokyo Denshoku Co., Ltd.). The measured value and the paper before copying (base paper)
Was calculated with a reflection densitometer and the difference from the value of the reflection density obtained was calculated, and the maximum value was defined as the fog density (FD).
Here, the document used for sampling on 5,000 sheets is a document in which the area ratio of black portions including black solid portions is 15%. Table 2 shows the evaluation results.

(C) Resolution Copying is performed using a character original having an area ratio of the black portion of 8%.
At the time of copying 50,000 sheets, copying was performed using a prescribed chart original (an original using a plurality of patterns in which a predetermined number of parallel straight lines were drawn per 1 mm), and the copied image was visually judged. Table 2 shows the evaluation results.

(D) Amount of electrification 50,000 copies were made using a character original having an area ratio of black portion of 8%. The charge amount of 200 mg of the developer was measured every 5,000 sheets using a "blow-off powder charge amount measuring device" (manufactured by Toshiba Chemical Co.), and the average value of the charge amount per 1 g of toner was calculated. Table 2 shows the evaluation results.

(E) Amount of Adhered Substances on Surface of Particles of Carrier Due to Spent: A character original having an area ratio of black portion of 8% was used for copying.
At the time of copying 50,000 sheets, the developer was sampled. The developer was placed on a 400-mesh sieve and sucked from below with a blower to separate the toner from the carrier.
5 g of the carrier remaining on the sieve was put into a beaker, and toluene was further added to the beaker to dissolve the toner component adhering to the particle surface of the carrier by means of the spent. After that, the toluene solution was discarded while the carrier was attracted from below the beaker with a magnet. This was repeated several times until the toluene became colorless, and then the toluene adhering to the carrier was evaporated in an oven, and the weight of the residue obtained was measured. The difference between the weight of the carrier initially put in the beaker and the weight after evaporation of toluene is the amount of the toner component (spent amount) attached to the particle surface of the carrier by the spent. The spent amount is represented by mg of the toner component attached to 1 g of the carrier. Table 2 shows the evaluation results.

(F) Toner Scattering 50,000 copies were made using a character original having an area ratio of the black portion of 8%. At this time, the toner scattering state in the copying machine was visually observed and evaluated according to the following criteria. ◯: No toner scatter x: Toner scatter is shown in Table 2.

(G) Presence or absence of white spots on the black solid part As shown in FIG. 10, a black solid part 3 of 50 mm × 50 mm
A manuscript 3 of 210 mm × 297 mm having three 1
The paper was passed in the direction Pa shown in the same figure, and the presence or absence of white spots was visually determined at three locations on the black solid portion of the 50,000th copy image.
Table 2 shows the evaluation results.

[0106]

[Table 2]

[Consideration of Evaluation Results] The toner obtained in Example 1 was stable in a very good state until the image density, fog density, resolution, and charge amount were copied 50,000 sheets. Further, the amount of the deposits of the carrier on the particle surface of the carrier was small, and the toner was not scattered.

Compared with the toner of Example 1, the toners of Examples 2 and 3 had a lower fog density and were good.

Further, in the toner of Comparative Example 1, the toner or the spacer particles adhered to the surface of the drum at the time of copying 50,000 sheets, and white spots were generated on the black solid portion, whereas
With the toners of Examples 1 to 3, white spots did not occur at all on the black solid part, and good images were obtained.

[0110]

As described above, according to the present invention, there is provided a toner containing no charge control agent, which is a main cause of spent during copying. The toner particles of this toner contain a fixing resin having an anionic polar group, and the toner particles contain magnetic powder at a predetermined ratio. Further, spacer particles are attached to the surfaces of the toner particles, and further metal stearate is further attached to the surfaces of the toner particles to which the spacer particles are attached. Therefore, the toner is efficiently charged and stable charging is obtained, so that the toner is not scattered during copying, the transfer efficiency is sufficient, and the copy image of the required density is stable for a long time. Obtained. Further, in the present invention, toner is less likely to adhere to the photoreceptor, and the smoothness of the surface of the obtained copy image can be increased, so that a glossy copy image can be obtained.

Such a two-component developer toner is preferably used in an electronic image forming apparatus such as an electrostatic copying machine or a laser beam printer.

[Brief description of drawings]

FIG. 1 shows a wavelength 2 of a methanol extract of the toner of the present invention.
It is a graph which shows the light absorbency in 00-700 nm.

FIG. 2 is a wavelength of 200 to 700 n of a methanol extract of a toner containing an azo chromium complex salt dye as a charge control agent.
It is a graph which shows the light absorbency in m.

FIG. 3 Wavelength 200 to 700 nm of a methanol extract of a toner containing a salicylic acid metal complex as a charge control agent.
It is a graph which shows the light absorbency in.

FIG. 4 is a schematic diagram of a carrier containing a toner containing an azo chromium complex salt dye as a charge control agent used in a two-component magnetic developer. 200-700 nm
It is a graph when the light absorbency in is measured.

FIG. 5 shows the mixing / stirring time when the operation of mixing / stirring the toner containing the charge control agent and the magnetic carrier or the mixing / stirring of the toner not containing the charge control agent and the magnetic carrier is continued. It is a graph which shows the relationship with a spent rate.

FIG. 6 shows the mixing / stirring time when the operation of mixing / stirring the toner containing the charge control agent and the magnetic carrier or the mixing / stirring of the toner not containing the charge control agent and the magnetic carrier is continued. It is a graph which shows the relationship with a charge amount.

FIG. 7 is a graph showing the relationship between the amount of the adhering substance of the carrier to which the toner component is attached due to the spent and the amount of the charge control agent in the toner that causes the spent.

FIG. 8 is a graph showing the relationship between the amount of spent and the mixing / stirring time when the operation of mixing / stirring each of the components in the toner and the magnetic carrier is continued.

FIG. 9 is an explanatory diagram illustrating occurrence of charging failure due to spent in a conventional two-component magnetic developer.

FIG. 10 is a schematic diagram of a document used for evaluating the presence or absence of white spots on a black solid portion.

[Explanation of symbols]

 1 Carrier Particles 2 Toner 22 Reverse Polarity Toner 3 Original 31 Black Solid Part Pa Paper Direction

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G03G 9/08 325 372 374 375 (72) Inventor Norio Kubo Osaka Prefecture No. Mita Kogyo Co., Ltd. (72) Inventor Kazuya Nagao 1-228 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo Co., Ltd. (72) Terumichi Asano 1-228 Tamatsukuri, Chuo-ku, Osaka No. Mita Industrial Co., Ltd.

Claims (5)

[Claims] 1. A two-component developer toner comprising a fixing resin and toner particles containing magnetic powder dispersed in the resin, wherein the fixing resin comprises a resin having an anionic polar group. The magnetic powder is contained in an amount of 0.1% by weight per 100 parts by weight of the fixing resin.
The toner particles are contained in the toner particles in a proportion of 1 to 5 parts by weight, the toner particles have a volume-based average particle diameter of 5 to 15 μm, and the toner particles have a volume-based average particle diameter of 0.05 to 1. A two-component developer toner, in which spacer particles of 0 μm are attached, and metal stearate is attached to the surface of the toner particles to which the spacer particles are attached. 2. Extraction liquid when extracted with methanol is 2
The toner according to claim 1, which has substantially no absorption peak in the region of 80 to 350 nm, and has an absorbance of substantially zero in the region of 400 to 700 nm. 3. The fixing resin 100 comprises the magnetic powder.
The toner according to claim 1, which is contained in a ratio of 0.5 to 3 parts by weight with respect to parts by weight. 4. The toner according to claim 1, wherein the metal stearate is at least one selected from the group consisting of zinc stearate and magnesium stearate. 5. The toner according to claim 1, wherein the metal stearate is selectively attached to the surface of the spacer particles.