JPH0876419A - Toner for binary system developer - Google Patents

Abstract

PURPOSE: To provide a toner that is sufficient enough in electrifiability, no scattering at time of copying, also adequate enough in transfer efficiency, and capable of securing the required density copied image stably for hours. 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 1) a polymer with an anionic polar group and a portion where wax is grafted, and 2) a composition comprising at least one side of compositions consisting of a polymer with the anionic polar group and another polymer with the portion where the wax is grafted. In this connection, the magnetic powder is contained in the toner grains at a rate from 0.1 to 5 pt.wt to 100 pts.wt. the fixing resin.

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. Further, 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, it increases the unit price of the toner despite 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 also a drawback that toner scattering occurs and transfer efficiency decreases.

[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]

The present invention relates to a two-component developer toner containing a fixing resin and a magnetic powder dispersed in the resin; the fixing resin comprises (1) anions. At least (1) a polymer having a polar group and a wax-grafted portion, and (2) a polymer having an anionic polar group and a wax-grafted portion. ) And (2), the magnetic powder is contained in the toner particles in a proportion of 0.1 to 5 parts by weight relative to 100 parts by weight of the fixing resin; By doing so, 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 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 1.0 μm.
Spacer particles of μm are attached.

[0011]

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 high image quality copying can be performed for a long period of 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 absorbance peaks due to these compounds are detected in the organic solvent extract of the toner of the present invention. For example, the toner of the present invention is an organic solvent,
For example, when extracted with methanol, the extracted liquid is 280 to
It has substantially no absorption peak in the region of 350 nm, and the absorbance in the region of 400 to 700 nm is substantially zero. Here, “having substantially no absorption peak” means that no absorption peak is detected at all in an extract obtained by extracting 0.1 g of toner with 50 ml of methanol, or even if it is detected, the absorbance at the peak position is 0.05. It means the following. 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, a polymer 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, in order to further enhance the function of the toner, a polymer having a wax-grafted portion is used, which improves the dispersion of the wax,
The spent property of the wax is improved, and the durability and the like are improved. Further, if necessary, spacer particles having a predetermined particle diameter are attached to the surfaces of the toner particles, so that the transfer efficiency from the photoconductor onto the transfer paper is enhanced.

The above will be described in detail below.

20% of the methanol extract of the toner of the present invention
The absorbance curve in the region of 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 28
It has substantially no absorption peak in the region of 0 to 350 nm,
And the absorbance in the region of 400 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 is 400 to 700 nm, and particularly 550 to 570 n.
m has a peak in the region (FIG. 2), and the absorbance curve of the methanol extract of the toner containing the salicylic acid 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 on the surface of the toner particles in a considerably high concentration. 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 in the region of 400 to 700 nm is examined, a peak due to the charge control agent is recognized in that region. For example, FIG. 2 shows the absorbance curve of the methanol extract of the carrier when a toner containing the azo chromium complex salt dye is used for a long time and a spent occurs, the absorbance curve of which is shown in FIG. In FIG. 4, a peak is recognized at the same position as that of the charge control agent in FIG. In the past, the spent was considered to occur because the resin for fixing the toner adheres to the surface of the particles of the carrier to form a resin film.
It has been found that one of the main causes of the spent generation is the migration of the charge control agent from the toner particles to the surface of the carrier particles.

The inventors further conducted the following experiment in order 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 deposits is shown in FIG. 5 as the percentage of spent relative to the total weight of the carrier having the deposits. 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 FIGS. 5 and 6. 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 by the spent, and this was plotted on the horizontal axis (shown as the spent amount), and the amount of the charge control agent in the toner component was plotted on the vertical axis. 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, the inventors mixed a charge control agent, a fixing resin, carbon black as a colorant, and wax with a carrier. -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 2
Since the particles 2 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 the absence of the charge control agent, mainly the lack of the charge amount, is due to the use of a 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 described above, as the second requirement, the magnetic powder is contained in the toner particles in a predetermined ratio, that is, 0.1 to 5 parts by weight based on 100 parts by weight of the fixing resin. This is adopted to compensate 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. The image density is low because the charge amount is insufficient. 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,
Therefore, the toner does not adhere sufficiently to the electrostatic latent image, resulting in a low image density.

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, a polymer having a wax-grafted portion is used as a fixing resin for toner particles. By grafting the wax into the polymer, the compatibility with the fixing resin is improved and the dispersibility of the wax is improved. As a result, even when the toner obtained by mixing the toner particles with the carrier particles is used for a long period of time, the wax hardly adheres to the surface of the carrier particles due to the spent.

On the other hand, the toner particles obtained by blending the fixing resin not grafted with wax and the wax are compatible because the fixing resin and the wax have different SP values (solubility parameters). Is poor and the wax does not disperse well in the resin. Therefore, in the obtained toner particles, the wax is present in a relatively large particle shape and non-uniformly, and the wax particles are also present on the surface of the toner particle. Therefore, when such toner particles are used, wax easily adheres to the surface of the carrier particles as a spent.

In the present invention, in order to further improve the transfer efficiency of the toner image, spacer particles having a particle diameter of 0.05 to 1.0 μm are preferably attached to the surface of the toner particles. The spacer particles can act as a fluidity improver for the toner particles and form a gap between the photoreceptor and the toner particles when attached to the electrostatic latent image on the photoreceptor. 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, so that the transfer efficiency becomes high. When the spacer particles are the same magnetic powder particles as those internally added to the toner particles, the binding ability between the toner particles and the particles of the carrier becomes higher, and the toner scattering and fog can be further reduced.

Fine particles having a particle diameter of about 0.015 μm have been used as an external additive as a conventional toner fluidity improving agent. 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.

[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 at least one of the following (1) and (2): ( A composition comprising 1) a polymer having an anionic polar group and having a wax grafted portion, and (2) a polymer having an anionic polar group and a polymer having a wax grafted portion.

The above-mentioned polymer (1) can be obtained by adding a wax when polymerizing a monomer containing a monomer having an anionic polar group. In the composition (2), the polymer having an anionic polar group is obtained by polymerizing a monomer containing a monomer having an anionic polar group, and the obtained resin is a homopolymer. Alternatively, it may be a copolymer. In the composition of (2) above,
A polymer having a wax-grafted portion is obtained by polymerizing another monomer having no anionic polar group,
Obtained by adding wax.

In the present specification, a wax-derived portion of a polymer having a wax-grafted portion is referred to as a wax portion. The polymer having a wax-grafted portion is a polymer prepared by adding a wax to a part of a monomer to be used and polymerizing the resulting reaction product with the remaining monomer. Can be. Further, it may be one prepared by polymerizing a reaction product obtained by polymerizing a part or all of the monomers used, by further adding wax.

The fixing resin of the present invention is preferably the polymer of the above (1), and a wax is added when a monomer having an anionic polar group and another monomer are polymerized. The composition thus obtained comprises a polymer having a wax-grafted portion. 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 widely used. 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 styrene sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid. Examples of the monomer having a phosphonic acid group include 2-acid phosphoxypropyl methacrylate, 2-acid phosphoxyethyl methacrylate and 3-chloro-2-
Acid phosphoxy propyl methacrylate etc. are mentioned.

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 other monomer having no anionic polar group is selected so that the resulting polymer has the fixability and chargeability required for the toner, and is a monomer having an ethylenically unsaturated bond. One or more combinations of monomers are 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.

Acrylic ester monomers are represented by the following general formula (I):

[0038]

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):

[0042]

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):

[0046]

[Chemical 3]

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

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

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

[0050]

[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):

[0054]

[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):

[0058]

[Chemical 6]

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

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

The wax added when polymerizing the above-mentioned monomer having an anionic polar group and / or other monomer is selected from the releasing agents usually used in toners.
That is, in the present specification, the wax includes various natural waxes and olefin resins. Examples of the olefin resin include polypropylene, polyethylene, propylene-ethylene copolymer and the like.
Especially, polypropylene is preferably used.

The wax portion of the polymer having the wax-grafted portion has a function of preventing the offset of the toner at the time of heat fixing, similarly to the release agent usually used for the toner.

The amount of the wax used is such that the weight part of the wax portion in the polymer having the wax grafted portion in 100 parts by weight of the fixing resin is 0.01-.
It is selected to be 6 parts by weight, preferably 0.1 to 4 parts by weight. If the weight of the wax portion is less than 0.01 parts by weight, the offset resistance at the time of heat fixing may be insufficient, and if it exceeds 6 parts by weight, poor charging occurs and the durability is lowered. Occurs.

The molecular weight of the wax is not particularly limited,
The average molecular weight is preferably selected from the range of 2,000 to 16,000, more preferably 3,000 to 6,000.

Specific examples of the polymer 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, Examples include ionomer resins. Furthermore, a polyester resin having an anionic polar group can be used. Similarly, a polymer having a wax-grafted portion, which is obtained by adding a wax during the polymerization of the above-mentioned monomers, has a styrene-acrylic acid copolymer or a styrene-maleic acid as a portion other than the wax portion. It may have a partial structure corresponding to an acid copolymer, an ionomer resin, or the like.

The polymer having an anionic polar group and a wax-grafted portion has an acid value of 2 to 30 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 preferably 5 to 15. In a composition comprising a polymer having an anionic polar group and a polymer having a wax-grafted portion, the acid value of the composition as a whole is preferably in the above range. 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 polymer or composition, that is, the concentration of the anionic polar group, is lower than the above range, the chargeability of the toner is insufficient. On the contrary, when it is higher than the above range, the toner exhibits hygroscopicity. It is not preferable because it has. Suitable fixing resins include at least one of the above-mentioned monomer having an anionic polar group, wax and the acrylic monomer of the formula (I).
A copolymer containing a seed as an essential component and, if necessary, a monomer of formula (II) to formula (VI) as an optional component is used. Each of the above monomers may be used alone or in combination of two or more in order to prepare the above resin.

As described above, the fixing resin used in the present invention contains (1) a polymer having an anionic polar group and a wax grafted moiety, and (2) an anionic polar group. A composition containing at least one of a polymer having a polymer and a polymer having a wax-grafted portion is used. This composition may further contain a polymer having no anionic polar group and a wax-grafted portion. 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.

Extender pigment Barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

The pigment is used in an amount of usually 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 olefin resins may be used in addition to the wax used for preparing the polymer having the above-mentioned wax-grafted portion.

(Preparation of Toner) The toner particles used in the toner of the present invention are produced 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. And is usually manufactured by a pulverizing and classifying method.

For example, the components for forming the toner particles are pre-mixed 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 preferably have a volume-based average particle diameter (median diameter by Coulter counter) of 5 to 15 μm, particularly 7 to 12 μm.

If necessary, a fluidity improving agent such as hydrophobic vapor phase silica particles may be attached to the surface of the toner particles as an external additive to improve the fluidity of the toner. 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 particle size per unit weight of the toner, that is, the total weight of the toner particles and the external additive is 0.1.
It is externally added in an amount of 1 to 2.0% by weight.

Further, in the present invention, preferably spacer particles having a particle size larger than that of the fluidity improver particles are externally added. As the spacer particles, 0.05 to
Either organic or inorganic inert particles of 1.0 μm, preferably 0.07 to 0.5 μm can be used. Materials for such inert particles include silica, alumina,
Examples thereof include titanium oxide, magnesium carbonate, acrylic resin, styrene resin, magnetic materials and the like. The spacer particles can function as a fluidity improver and also have a function of enhancing transfer efficiency as described above. As the spacer particles, it is generally preferable to use the same magnetic powder as that contained in the toner particles, particularly fine particulate iron trioxide tetraoxide (magnetite) particles. The use of magnetic powder particles as the spacer particles effectively acts on the toner scattering as described above. The spacer particles are 10% by weight or less based on the total weight of the toner, preferably 0.1-10.
%, More preferably 0.1 to 5% by weight. If it is excessive, the density of the copied image will be insufficient.
When magnetic powder is used as the spacer particles, the total amount of the magnetic powder and the magnetic powder contained in the toner particles is preferably 10 parts by weight or less based on 100 parts by weight of the fixing resin. If it is excessive, the image density may be low.

In order to externally add the fluidity improver and the spacer particles to the toner particles, for example, the fluidity improver and the spacer particles are sufficiently mixed, and this mixture is added to the toner particles and sufficiently crushed. Is good. As a result, the spacer particles adhere to the surface of the toner 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 a 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, and particularly 97: 3 to 9.
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 performed 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.

[0086]

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

(Production Example 1) A polymer having a wax-grafted portion was prepared by the following steps.

Weight ratio of styrene, butyl methacrylate and acrylic acid as monomers for low molecular weight substances 80: 1
5: 5 mixture (100 parts by weight), polypropylene as wax (0.6 parts by weight; average molecular weight 4,000)
0) and the polymerization initiator were mixed in a soluble solvent and stirred to dissolve. The resulting mixed solution is charged into a reaction kettle,
Polymerization was performed while stirring well with a stirring blade. The polymerization reaction for preparing a low molecular weight substance is generally 3 to 1 at 60 to 250 ° C.
Do it for 0 hours. In this production example, polymerization was carried out at 150 ° C. for 5 hours. The solvent was removed from the reaction mixture and the residue was dried to obtain a low molecular weight polymer having a wax-grafted portion.

The above low molecular weight substance (100 parts by weight), polypropylene as a wax (5.4 parts by weight; average molecular weight 4,000), styrene as a monomer for polymer,
Weight ratio of butyl methacrylate and acrylic acid 70: 2
The 5: 5 mixture (100 parts by weight) and the polymerization initiator were mixed in a soluble solvent and stirred to dissolve. The obtained mixed solution was put into a reaction kettle and polymerization was performed while stirring well with a stirring blade. The polymerization reaction for preparing the polymer is generally carried out at 50 to 200 ° C. for 5 to 24 hours. In this production example, polymerization was carried out at 80 ° C. for 15 hours. The solvent was removed from the reaction mixture, and the residue was dried to obtain a polymer having a low molecular weight substance and a high molecular weight substance and having a wax-grafted portion.

(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.

To the toner particles, 0.35 parts by weight of hydrophobic silica fine particles having an average particle diameter of 0.015 μm as a fluidity improving agent was added to 100 parts by weight of the toner particles, and further, as spacer particles, an average particle diameter was set. Alumina particles having a particle size of 0.3 μm were added (externally added) at a ratio of 0.6 parts by weight to 100 parts by weight of the toner particles, and mixed for 2 minutes with a Henschel mixer to obtain a toner.

Comparative Example 1 A polymer having no wax-grafted portion was obtained in the same manner as in Example 1 except that polypropylene as a wax was not added as a fixing resin during the polymerization. It was Wax (polypropylene; average molecular weight 4,000) as a release agent for the polymer
Was obtained in the same manner as in Example 1 except that 3 parts by weight was mixed with 100 parts by weight of the fixing resin.

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

(A) Transfer Efficiency The toner amount in the toner hopper before the start of copying and the toner amount in the toner hopper after copying a predetermined number of sheets were measured, and the toner consumption amount was calculated from the difference. On the other hand, the amount of toner collected in the cleaning process during the copying of a predetermined number of sheets was measured and used as the toner recovery amount. From these values,
The transfer efficiency of the toner was calculated by the following formula (i). Here, the original used for copying is a character original in which the area ratio of the black portion is 8%.

This evaluation was carried out in order to carry out the following evaluation tests (b).

[0098]

[Equation 1]

(B) Image Density (ID) Copying is performed using a character original having an area ratio of black portion of 8%.
Copying was continued until the transfer efficiency was less than 70%. 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.

(C) Fog Density (FD) Copying was performed using a character original having an area ratio of black portion of 8%.
Copying was continued until the transfer efficiency was less than 70%. 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 difference between the measured value and the value of the reflection density obtained by measuring the paper (base paper) before copying with a reflection densitometer was calculated, and the maximum value was defined as the fog density (FD). 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.

(D) Resolution Copying is performed using a character original having an area ratio of black portion of 8%.
At the time of copying 50,000 sheets (at that time when the transfer efficiency has become less than 70%), the prescribed chart original (an original using a plurality of patterns in which a predetermined number of parallel straight lines are drawn per 1 mm) Was copied, and the copied image was visually judged. Table 2 shows the evaluation results.

(E) Amount of charge Copying is performed using a character original having an area ratio of black portion of 8%.
Copying was continued until the transfer efficiency was less than 70%. 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.

(F) 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.

(G) Toner Scattering Copying is performed using a character original having an area ratio of the black portion of 8%.
Copying was continued until the transfer efficiency was less than 70%. 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.

(H) Durability The toner transfer efficiency was calculated from the toner consumption amount after copying 10,000 sheets and the collected toner amount. The durability was defined as the number of sheets when the transfer efficiency became less than 70% for the first time.
Table 2 shows the evaluation results.

[0106]

[Table 2]

[Consideration of Evaluation Results] Obtained in Example 1,
A toner using a polymer having a wax-grafted portion has stable image density, fog density, resolution, and transfer efficiency, and has a durability of 100,000 sheets.
It was far superior to the comparative example of 60,000 sheets. No toner scattering was observed.

The reason why the durability of the toner was lowered in Comparative Example 1 was that the wax as the release agent adhered to the carrier, as shown by the comparison at the time of copying 50,000 sheets, so that the toner was relatively spent. It is considered that the amount increased.

[0109]

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, by using a polymer having a wax-grafted portion in the fixing resin, it is possible to more effectively prevent the spent as compared with the case where the wax is not grafted. Further, spacer particles having a predetermined particle diameter are attached to the surface of the toner particles as needed. Therefore, the chargeability of the toner is sufficient, the toner does not scatter during copying, the transfer efficiency is sufficient, and a copy image having a required density can be stably obtained for a long time. 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 the area | region of 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.

[Explanation of symbols]

 1 Carrier Particles 2 Toner 22 Reverse Toner

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location G03G 9/08 325 365 372 374 (72) Inventor Norio Kubo 1-28 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo (72) Inventor, Kazuya Nagao, 1-228 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo Co., Ltd. (72) Terumi Asano, 1-2-2, Tamatsukuri, Chuo-ku, Osaka Mitako Business

Claims (4)

[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 (1) an anionic polar group. A polymer having a wax-grafted moiety, and (2) at least (1), (2) a composition comprising a polymer having an anionic polar group and a polymer having a wax-grafted moiety. 2), wherein the magnetic powder is 0.
A two-component developer toner, which is contained in the toner particles in an amount of 1 to 5 parts by weight. 2. An extract obtained by extraction with methanol.
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 volume-based average particle diameter of the toner particles is 5
2. The toner according to claim 1, wherein spacer particles having a volume-based average particle diameter of 0.05 to 1.0 μm are attached to the surface of the toner particles.