JPH0876470A - Binary system developer - Google Patents

Abstract

PURPOSE: To provide a binary system developer which does not contain any charge control agent, which contains toner having a sufficient chargeability, which does not scatter the toner during copying, and with which a copied image having a required density is stably obtained for a long time. CONSTITUTION: Toner particles contain fixing resin, and magnetic powder dispersed in the resin, the fixing resin being a composition including one kind of styrene-acrylic group polymer, having an anionic polar group, a component having an alkyl group with a carbon number of more than 12 in the side chain, and grafted wax component. The styrene-acrylic group polymer satisfies the following conditions: (a) a peak molecular weight of 4,000 to 30,000, (b) a mean molecular weight of 70,000 to 200,000, and (c) an acid value of 4 to 20. Each of particles of the carrier a core particle and a cover layer with which the core particle is covered, the cover layer being made of a resin composition which contain thermosetting resin.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a two-component developer,
More specifically, it is a long-life two-component developer that has good transfer efficiency and can obtain a copy image of desired density over a long period of time, even though it does not contain a charge control agent in the toner. The present invention relates to a developer preferably used in an electrophotographic image forming apparatus such as a 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 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 two-component type developer which does not cause spent even after long-term use and, as a result, maintains good image quality and has stable transfer efficiency.

[0007]

The present invention is a two-component developer comprising a toner and a carrier; the toner comprises toner particles; the toner particles are a fixing resin, and in the resin. The fixing resin is a composition containing at least one styrene-acrylic polymer; the at least one styrene-acrylic polymer is an anionic polar group, a side chain. A component having an alkyl group having 12 or more carbon atoms in the chain and a grafted wax component each independently or in combination; the styrene-acrylic polymer satisfies the following conditions: (a) The polymer The molecular weight peak is 4,000 to 30,
000; (b) the weight average molecular weight of the polymer is 70,000 to 200,000; (c) the acid value of the polymer is 4 to 20; the magnetic powder is 100 parts by weight of the fixing resin. 0 for the department.
1 to 5 parts by weight is contained in the toner particles; the carrier particles have core particles and a coating layer that coats the core particles; the core particles are represented by the following formula (A): The magnetic material is: MOFe ₂ O ₃ (A) where M is Cu, Zn, Fe, Ba, Ni, Mg, M
n is a metal selected from the group consisting of Al and Co; the coating layer is a resin composition containing a thermosetting resin; and the degree of curing of the coating layer is 85.
% Or more; thereby achieving the above object.

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 fixing resin is a styrene-acrylic polymer having a combination of an anionic polar group, a component having an alkyl group having 12 or more carbon atoms in its side chain, and a grafted wax component. including.

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.
m spacer particles are attached.

In a preferred embodiment, the core particles have a particle size of 50 to 150 μm.

In a preferred embodiment, the weight of the coating layer is 0.001 to 2.5 parts by weight based on 100 parts by weight of the core particles.

In a preferred embodiment, the thermosetting resin is a modified or unmodified silicone resin, thermosetting acrylic resin, thermosetting styrene-acrylic resin, phenol resin, urethane resin, thermosetting polyester resin. , An epoxy resin, and an amino resin.

[0015]

The two-component developer of the present invention does not contain any charge control agent such as an azo dye or a metal complex of oxycarboxylic acid. Therefore, as will be described later, the spent due to the charge control agent is not generated, so that high-quality image copying can be performed for a long time. Since the toner in the developer contains no charge control agent, such a charge control agent, that is, a dye-based compound, is not detected from the toner by any chemical or physical means. For example, these compounds are not detected by a chemical reaction in the toner used in the developer of the present invention. Alternatively, absorption peaks due to these compounds are not detected at all in the organic solvent extract of the toner used in the developer of the present invention. For example, when the toner used in the developer 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 40
The absorbance in the region of 0 to 700 nm is substantially zero. Here, “having substantially no absorption peak” means that no absorption peak was detected in the extract obtained by extracting 0.1 g of toner with 50 ml of methanol, or even if it was detected, the absorbance at the peak position was 0. It means less than or equal to 05. 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 of the present invention, the instability of the charge amount due to the fact that the toner does not contain the above charge control agent is compensated by the following matters. Firstly, the styrene-acrylic 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. That is. In the present invention, in order to further enhance the function of the toner, a styrene-acrylic polymer having a component having an alkyl group having 12 or more carbon atoms in the side chain and a grafted wax component independently or in combination is used. Therefore, the fixability and the offset resistance are improved, and the occurrence of spent is suppressed. 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. In the present invention, the function of the developer is such that the degree of curing of the layer is 85% or more. As a result, the occurrence of spent is further reduced, and a developer having excellent image stability in which filming on the photosensitive drum does not occur can be obtained.

The above will be described in detail below.

FIG. 1 shows the absorbance curve of the methanol extract of the toner used in the developer of the present invention at 200 to 700 nm. As shown in this curve, this extract does not have any peaks attributed to each charge control agent.
That is, it has substantially no absorption peak in the region of 280 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-type chromium metal complex salt dye as the charge control agent is 400 to 700 nm, especially 5
The toner has a peak in the range of 50 to 570 nm (FIG. 2), and the absorption curve of the methanol extract of the toner containing the salicylic acid metal complex as the charge control agent is 28.
It has a peak in the region of 0 to 350 nm (FIG. 3).

The absorption due to the charge control agent is observed in the methanol extract of the toner containing the above charge control agent because the charge control agent is present at a considerably high concentration on the toner particle surface. 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 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 means of the spent, the abscissa represents this (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, 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 22
Are formed on the surface of the particles 1 of the carrier, toner scattering occurs, and the transfer efficiency decreases.

As described above, the charge control agent is
Since it may contain a heavy metal, it is preferable not to contain it. Further, as described above, it is a main cause of spent, causing toner scattering, lowering of transfer efficiency, and the like. Therefore, the toner used in the developer of the present invention In, the charge control agent is not contained at all.

The instability of the charge amount due to the absence of the charge control agent, mainly the lack of the charge amount is as described above. First, the styrene-acrylic polymer having an anionic polar group is used for the toner. It is supplemented by using. 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, on the contrary, since the charging property of the toner particles in the vicinity of the surface is not so large, the coupling between the toner particles and the carrier particles in the magnetic brush at the time of development by the Coulomb force 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 above 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 becomes too large, so that 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, a toner may contain a charge control agent, so that spent may occur.

In the present invention, the fixing resin for toner particles contains a styrene-acrylic polymer having, independently or in combination, a component having an alkyl group having 12 or more carbon atoms in the side chain and a grafted wax component. Normal,
When the transfer image is heat-fixed with a heat roll, a release agent is contained in the toner particles in order to prevent offset onto the transfer paper. Various waxes are used as the release agent. These have poor SP compatibility (solubility parameter value) with the fixing resin that is usually used when they are heated and kneaded with the fixing resin and the magnetic powder in the toner manufacturing process, and thus the above-mentioned heating and kneading Sometimes it is difficult to disperse in resin sufficiently. Therefore, in the toner particles obtained, these waxes are present in relatively large particles in a non-uniform manner,
These particles may also be present on the surface of the toner particles. Therefore, when such toner particles are used, the wax as the release agent adheres to the surface of the carrier particles as a spent. However, in the styrene-acrylic polymer contained in the fixing resin used in the present invention, since the wax is chemically bonded to the resin by grafting, the wax as described above is detached from the toner particles. The occurrence of spent on the carrier due to is extremely small and the offset resistance is excellent. Although the fixing resin of the present invention has such excellent performance, it is added at the time of toner production because the styrene-acrylic polymer has a component having an alkyl group having 12 or more carbon atoms in its side chain. The dispersibility of the wax is also improved, and the life of the toner can be extended.

Further, in the present invention, the weight average molecular weight of the styrene-acrylic polymer, the peak of the molecular weight and the acid value are specified, whereby the spent resistance, the fixability, the pulverizability at the time of toner production, and the high It is possible to improve both the charging stability when wet.

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 particles of the same magnetic powder 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 insufficient charging property of the toner particles is also compensated. .

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, a specific magnetite or ferrite is used as a material for the core particles of the carrier. Since these compounds have little change in electric resistance due to environmental changes or changes with time, they can impart a stable charging property to the developer. Further, when a magnetic field is applied in the developing device, soft ears can be formed, so that the toner image formed on the photoconductor is less likely to be disturbed, and so-called white stripes do not occur in the image of the copy.

In the present invention, in order to further enhance the function as a developer, the coating layer of carrier particles contains a thermosetting resin, and the coating layer has a curing degree of 85% or more. Using a thermosetting resin as the coating layer of the carrier particles, wear resistance of the carrier, hardness, non-adhesiveness,
It is preferable because it improves heat resistance and durability. In the present invention, by setting the degree of cure to 85% or more, the cured product has a more dense structure, the uniformity of the obtained coating layer surface is improved, and the effect of preventing the coating resin from falling off and spent is further enhanced. Furthermore, since the hardness of the coating layer is improved, filming and spent on the photosensitive drum are less likely to occur.

Here, the degree of cure is a value defined by the following formula. After forming a coating layer on the core particles and curing the core particles, the obtained carrier particles are treated with a solvent (resin used in the coating layer). It is the ratio of the coating layer remaining on the core particles without being removed by the solvent after washing with a composition capable of dissolving or dispersing the composition).

[0037]

[Equation 1]

Here, C is the amount of carbon measured by elemental analysis or the like.

[0039]

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 styrene-acrylic polymer, and the at least one styrene. The acrylic polymer has an anionic polar group, a component having an alkyl group having 12 or more carbon atoms in the side chain, and a grafted wax component, independently or in combination, and the styrene-acrylic polymer Satisfies the following conditions: (a) The molecular weight peak of the polymer is 4,000 to 30,
000, (b) the weight average molecular weight of the polymer is 70,000 to 200,000, and (c) the acid value of the polymer is 4 to 20.

The styrene-acrylic polymer used for the fixing resin is obtained by copolymerizing a monomer containing a monovinyl aromatic monomer and an acrylic monomer.

In the present specification, the "side chain" of a monomer means a site capable of forming a side chain of a (co) polymer obtained by using the monomer. The grafted wax portion of the polymer grafted with wax is called a grafted wax component.

The anionic polar group is obtained by polymerizing a monomer containing a monomer having an anionic polar group. Even if the obtained polymer is a homopolymer, another monomer or It may be a copolymer with a monomer containing a monomer having an alkyl group having 12 or more carbon atoms in its side chain. Similarly, the component having an alkyl group having 12 or more carbon atoms in the side chain is obtained by polymerizing a monomer containing a monomer having an alkyl group having 12 or more carbon atoms in the side chain, and the obtained polymer May be a homopolymer or a copolymer with another monomer. The wax grafted polymer is
A reaction product obtained by adding wax to a part of a monomer used, for example, a monomer having an anionic group and / or a monomer having an alkyl group having 12 or more carbon atoms in a side chain to polymerize the reaction product, Further, it may be prepared by polymerizing the remaining monomer, for example, a monomer having an anionic polar group and / or a monomer having an alkyl group having 12 or more carbon atoms in the side chain.

Any of the above copolymers may be a random copolymer, a block copolymer or a graft copolymer.

The fixing resin of the present invention is preferably a styrene-acrylic polymer having a combination of an anionic polar group, a component having an alkyl group having 12 or more carbon atoms in its side chain, and a grafted wax component. It is a composition containing.

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 generally 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 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.

Next, the monomer having an alkyl group having 12 or more carbon atoms in its side chain will be described. The alkyl group having 12 or more carbon atoms includes an acyclic linear hydrocarbon group, an acyclic branched hydrocarbon group and a cyclic hydrocarbon group.

As the monomer having an alkyl group having 12 or more carbon atoms in the side chain, 1 carbon atom bonded by an ester bond is used.
Acrylic ester-based monomer such as acrylic acid or methacrylic acid ester having two or more alkyl groups, vinyl ester-based monomer having an alkyl group having 12 or more carbon atoms bonded by an ester bond, and an ether bond bonded A vinyl ether monomer having an alkyl group having 12 or more carbon atoms, an olefin monomer having 14 or more carbon atoms having a double bond at the 1-position, and at least one substituent consisting of an alkyl group having 12 or more carbon atoms Monovinyl aromatic monomer, having a double bond at the 1st and 3rd positions and having 12 carbon atoms
Examples thereof include diolefin-based monomers having at least one alkyl group, and these may be used alone or in combination of two or more.

The acrylic ester type monomer having an alkyl group having 12 or more carbon atoms in the side chain is represented by the following general formula (I)
Indicated by:

[0051]

Embedded image

Here, R ¹ is a hydrogen atom or a lower alkyl group, and R ² is an alkyl group having 12 or more carbon atoms.

Examples of such a monomer include lauryl acrylate, tridecyl acrylate, stearyl acrylate, docosyl acrylate, dicyclohexylmethyl acrylate, dicyclohexylpropyl acrylate, cyclododecyl acrylate, cycloundecanemethyl acrylate, methacryl Lauryl acid, tridecyl methacrylate,
Examples thereof include stearyl methacrylate, docosyl methacrylate, dicyclohexylmethyl methacrylate, dicyclohexylpropyl methacrylate, cyclododecyl methacrylate, cycloundecane methyl methacrylate and the like.

The vinyl ester monomer having an alkyl group having 12 or more carbon atoms in the side chain is represented by the following general formula (II):

[0055]

Embedded image

Here, R ³ is an alkyl group having 12 or more carbon atoms.

Examples of such a monomer include vinyl laurate, vinyl tridecanoate, vinyl stearate, vinyl docosanoate, vinyl triacontanate, vinyl pentylcyclohexanoate, vinyl dicyclohexyl acetate and the like.

The vinyl ether type monomer having an alkyl group having 12 or more carbon atoms in the side chain is represented by the following general formula (III)
Indicated by:

[0059]

[Chemical 3]

Here, R ⁴ is an alkyl group having 12 or more carbon atoms.

Examples of such a monomer include vinyl lauryl ether, vinyl stearyl ether, vinyl docosyl ether, vinyl cyclododecyl ether and the like.

The mono-olefinic monomer having a carbon number of 14 or more and having a double bond at the 1-position is represented by the following general formula (IV):

[0063]

[Chemical 4]

Here, R ⁵ and R ⁶ are each independently a hydrogen atom or an alkyl group having 12 or more carbon atoms.

Examples of such a monomer include 1-tetradecene and 1-eicosene.

The monovinyl aromatic monomer having at least one substituent having an alkyl group having 12 or more carbon atoms is represented by the following general formula (V):

[0067]

[Chemical 5]

Here, R ⁷ is a hydrogen atom, a lower alkyl group, an alkyl group having 12 or more carbon atoms, or a halogen atom, and R ⁸ is an alkoxy group, an amino group, a nitro group, or an alkyl group having 12 or more carbon atoms. And Φ is a phenylene group. The phenylene group may further have another substituent, and in this case, the substituent includes a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group, an alkyl group having 12 or more carbon atoms, and the like. it can. Further, the alkyl group having 12 or more carbon atoms has an ester bond,
They may be bonded via a (thio) ether bond or an amide bond.

Examples of such a monomer include m- or p
-Lauryl styrene, m-stearyl or p-stearyl styrene, α-methyl-3-stearyl styrene, m
-Or p-stearoxystyrene, 4-vinylbenzoic acid stearyl, 4-stearoylaminostyrene and the like can be mentioned.

The diolefin monomer having a double bond at the 1- and 3-positions and at least one alkyl group having 12 or more carbon atoms is represented by the following general formula (VI):

[0071]

[Chemical 6]

Here, R ⁹ , R ¹⁰ and R ¹¹ are each independently a hydrogen atom, a lower alkyl group, an alkyl group having 12 or more carbon atoms, or a halogen atom.

Examples of such a monomer include 1,3-hexadecadiene, 1,3-docosadiene and 2-methyl-
1,3-docosadiene and the like can be mentioned.

The above-mentioned monomer having an anionic polar group and / or a monomer having an alkyl group having a carbon number of 12 or more in the side chain, and other monomer to be polymerized as the case requires, are obtained. The combination is selected to have the fixability and chargeability required of the toner, and a combination of one or more monomers having an ethylenically unsaturated bond is used.
Examples of such monomers include acrylic ester-based monomers, monovinyl aromatic-based monomers, vinyl ester-based monomers, vinyl ether-based monomers, diolefin-based monomers,
There are mono-olefin type monomers.

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

[0076]

[Chemical 7]

Here, R ¹² is a hydrogen atom or a lower alkyl group, and R ¹³ 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.

The monovinyl aromatic monomer as another monomer is represented by the following general formula (VIII):

[0080]

Embedded image

Here, R ¹⁴ is a hydrogen atom, a lower alkyl group or a halogen atom, R ¹⁵ 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-based monomer as another monomer is represented by the following general formula (IX):

[0084]

[Chemical 9]

Here, R ¹⁶ is a hydrogen atom or a lower alkyl group.

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

Vinyl ether type monomers as other monomers are represented by the following general formula (X):

[0088]

[Chemical 10]

Here, R ¹⁷ 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-based monomer as another monomer is represented by the following general formula (XI):

[0092]

[Chemical 11]

Here, R ¹⁸ , R ¹⁹ and R ²⁰ are each independently a hydrogen atom, a lower alkyl group or a halogen atom.

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

The mono-olefinic monomer as another monomer is represented by the following general formula (XII):

[0096]

[Chemical 12]

Here, R ²¹ and R ²² are each independently a hydrogen atom or a lower alkyl group.

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

The wax added at the time of polymerizing the above-mentioned monomer is selected from the release agents usually used for 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-derived portion of the polymer having a grafted wax component has a function of preventing toner offset at the time of heat fixing, similarly to the release agent usually used for toner.

The wax is used in an amount of 0.01 to 6 parts by weight, preferably 0.1 to 6 parts by weight, based on 100 parts by weight of the fixing resin, in the polymer having the grafted wax component. It is selected to be 4 parts by weight. If the weight of the wax portion is less than 0.01 parts by weight, the offset resistance during heat fixing may be insufficient,
If it exceeds 6 parts by weight, poor charging occurs and durability deteriorates. The molecular weight of the wax is not particularly limited, but the average molecular weight is preferably 2,000 to 1
From the range of 6,000, more preferably from 3,000 to
It is selected from the range of 6,000.

The amount of the monomer having an alkyl group having 12 or more carbon atoms in the side chain is 0.1 to 2 with respect to the total weight of the monomer.
It is desirable that 0 part by weight, preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight is copolymerized. When the copolymerization amount of the monomer having an alkyl group having 12 or more carbon atoms in the side chain is less than the above range, the compatibility between the wax and the fixing resin is insufficient, and when it is more than the above range, the fixing amount is large. Since the Tg of the resin is low, the storage stability is low.

Specific examples of the polymer having an anionic polar group obtained by polymerizing the above-mentioned monomer and an alkyl group having a carbon number of 12 or more in the side chain include styrene- (meth) acrylic acid- (meth) acryl. Acid stearyl copolymer, styrene- (meth) acrylic acid ester- (meth) acrylic acid stearyl- (meth) acrylic acid copolymer, styrene-
Examples include stearyl (meth) acrylate-maleic acid copolymers. Furthermore, a polyester resin having an anionic polar group can be used. Similarly, a polymer having a grafted wax component, which is obtained by adding a wax at the time of polymerizing the above-mentioned monomer, has styrene- (meth) acrylic acid- (meth) acrylic acid as a part other than the grafted wax component. Stearyl copolymer, styrene-
It may have a partial structure corresponding to (meth) acrylic acid ester- (meth) acrylic acid stearyl- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid stearyl-maleic acid copolymer and the like.

The styrene-acrylic polymer used in the present invention has a ratio such that when the anionic polar group is present in the form of a free acid, the acid value is 4 to 20, preferably 5 to 15. It is desirable to have an anionic polar group. 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 above-mentioned acid value, that is, the concentration of the anionic polar group, is lower than the above range, the charging property of the toner is insufficient, and when it is higher than the above range, the toner has hygroscopicity, which is not preferable. .

Further, the peak of the molecular weight of the styrene-acrylic polymer is 4,000 to 30,000, preferably 6,000 to 20,000. When the peak of the molecular weight of the polymer is less than 4,000, the spent resistance cannot be expected to be sufficiently improved. If it exceeds 30,000, the pulverizability will decrease.

The weight average molecular weight of the styrene-acrylic polymer is 70,000 to 200,000, preferably 80,000 to 150,000. If it is less than 70,000, the obtained toner is over-pulverized, so that the toner particles tend to be easily broken.

Suitable fixing resins are obtained from styrene, acrylic acid or methacrylic acid, at least one of the acrylic monomers of formula (I) and wax and, if desired, of formula (II ) To any of the monomers of formula (VI) can be copolymerized as an optional component. Further, other monomers may be copolymerized if necessary. Each of the above monomers may be used alone or in combination of two or more in order to prepare the above resin.

As the fixing resin used in the present invention, the composition containing the styrene-acrylic polymer is used.
This composition may contain, in addition to the above-mentioned polymer, an anionic polar group, a component having an alkyl group having 12 or more carbon atoms in the side chain, and a polymer having no grafted wax component. . In that case, the proportion of the anionic polar group, the proportion of the component having an alkyl group having 12 or more carbon atoms in the side chain, and the proportion of the wax portion in the entire composition are preferably in the above ranges.

(Method for Producing Styrene-Acrylic Polymer Used for Fixing Resin) The styrene-acrylic polymer having a grafted wax component used in the present invention is
It can be manufactured as follows.

Solvents capable of dissolving both monomer, polymer and wax (eg toluene, xylene etc.)
Then, the monomer for low molecular weight substance, the wax and the polymerization initiator are mixed and stirred. This mixed solution is put into a reaction kettle, and the wax is grafted and polymerized at 60 to 250 ° C. for 3 to 10 hours while stirring well with a stirring blade. After degassing and drying the solution, a low molecular weight polymer is obtained. To get Next, the monomer for polymer, the polymer of low molecular weight obtained above and the polymerization initiator are mixed and stirred in a solvent in which both the monomer and the polymer can be dissolved. This mixed solution is put into a reaction kettle and polymerized at 60 to 200 ° C. for 5 to 24 hours while stirring well with a stirring blade, and then the solution is degassed and dried to obtain a desired polymer.

(Magnetic Powder) As the magnetic powder contained (internally added) in the toner particles, any of the magnetic powders conventionally used for a one-component magnetic toner 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 above 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 may 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 pigments Barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

The above 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 natural waxes and low molecular weight olefin resins are used. As the olefin resin, polypropylene, polyethylene,
Propylene-ethylene copolymer and the like can be used,
Polypropylene is particularly preferred.

(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 / classifying method, a melt granulation method, a spray granulation 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 improver 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 the silica particles is usually about 0.015 μm in the primary particle size, and is 0.1% per the total weight of the toner, that is, the total weight of the toner particles and the external additive.
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 to the toner particles. As the spacer particles, 0.05 to 1.0 μm, preferably 0.07 to 0.
Either 5 μm organic or inorganic inert particles can be used. Examples of the material of such inert particles include silica, alumina, titanium oxide, magnesium carbonate, acrylic resin, styrene resin, magnetic material 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 contained in an amount of 10% by weight or less, preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, based on the total weight of the toner. If it is excessive, the density of the copied image will be insufficient. When the 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 improving agent and the spacer particles to the toner particles, for example, the fluidity improving agent 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 used in the developer of the present invention is obtained.

(Carrier Particles) The carrier particles used in the developer of the present invention are particles having a double structure having core particles and a coating layer for coating the core particles. This core particle is made of a magnetic material represented by the following formula (A): MOFe ₂ O ₃ (A) where M is Cu, Zn, Fe, Ba, Ni, Mg, M
It is at least one metal selected from the group consisting of n, Al and Co.

The compound represented by the above formula (A) is composed of magnetite (when M is Fe) or ferrite (M is F).
(for metals other than e), M is Cu, Zn, Mn,
Ferrites such as Ni and Mg are preferably used. These magnetites or ferrites have a small rate of change in electric resistance with the passage of time, and can form soft ears when a magnetic field is applied in the developing device. The core particles made of these magnetic materials have a particle diameter of 30 to 200.
μm, preferably 50 to 150 μm. These core particles are obtained by granulating the fine particles of the magnetic material into spherical particles by means such as spray granulation and then firing. This core particle has a volume resistivity of 10 ⁵ to 1
It is 0 ⁹ Ω · cm, preferably 10 ⁶ to 10 ⁸ Ω · cm. The saturation magnetization of the core particles is in the range of 30 to 70 emu / g, preferably 45 to 65 emu / g.

The resin composition constituting the coating layer of carrier particles contains a thermosetting resin. Examples of the thermosetting resin include modified or unmodified silicone resin, thermosetting acrylic resin, thermosetting styrene-acrylic resin, phenol resin, urethane resin, thermosetting polyester resin, epoxy resin and amino resin. . Such a thermosetting resin increases in molecular weight by being heated and cured,
It becomes insoluble in the solvent. In order to adjust the curing degree to 85% or more, the heating temperature and the heating time may be adjusted. In the present invention, the coating layer may contain a thermoplastic resin as long as the characteristics of the coating layer are not deteriorated.
Examples of the thermoplastic resin include thermoplastic acrylic resin, thermoplastic styrene-acrylic resin, polyester resin, polyamide resin, and olefin-based copolymer resin.
These may be used alone or in combination of two or more.

Further, in the resin composition, if necessary,
Silica, alumina, carbon black, fatty acid metal salt,
Additives such as a silane coupling agent and silicone oil are contained, and these have the function of adjusting the characteristics of the coating layer.

(Preparation of Carrier) The resin composition is applied to the surface of the core particles by a known method to form a coating layer. For example, by mixing a solution or dispersion of the resin composition with core particles, coating the solution or dispersion of the resin composition on the surface of the core particles, drying if necessary, and curing by heating or the like. A coating layer is formed.
In forming the coating layer, any of commonly used dipping method, spraying method, fluidized bed method, moving bed method, rolling bed method and the like can be used. As a solvent capable of dissolving or dispersing the resin composition, a general organic solvent, for example, an aromatic hydrocarbon solvent such as toluene and xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, a ketone solvent such as cyclohexanone, tetrahydrofuran, Cyclic ethers such as dioxane, alcohols such as ethanol, propanol and butanol, cellosolve solvents such as ethyl cellosolve and butyl cellosolve,
Ester-based solvents such as ethyl acetate and butyl acetate, amide-based solvents such as dimethylformamide and dimethylacetamide, and the like can be appropriately used depending on properties such as solubility of the resin to be used.

The particle diameter of the thus obtained carrier is 30 to 200 μm, preferably 50 to 150 μm. The weight of the coating layer of carrier particles is 100%
The amount is 0.001 to 2.5 parts by weight, preferably 0.005 to 2.0 parts by weight. The volume resistivity of particles of the obtained carrier is 10 ⁵ to 10 ¹³ Ω · cm, preferably 10 ⁷ to 10 ¹² Ω · cm, and the saturation magnetization is 3
0 to 70 emu / g, preferably 45 to 65 emu / g
Is in the range.

(Preparation of Developer) A two-component developer is obtained by mixing the above toner and carrier. The mixing ratio of carrier and toner is generally 98: 2 to 90: 1.
A weight ratio of 0, particularly a weight ratio of 97: 3 to 94: 6 is preferred.

Using the two-component developer 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.

[0132]

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

(Production Example 1) A styrene-acrylic polymer having an anionic group, a component having an alkyl group having 12 or more carbon atoms in its side chain and a grafted wax component was prepared by the following steps.

Weight ratio of styrene, butyl methacrylate and acrylic acid as monomers for low molecular weight substances 80: 1
7: 3 mixture (100 parts by weight), polypropylene as wax (0.4 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 wax-grafted low molecular weight polymer.

The above low molecular weight substance (100 parts by weight), polypropylene as a wax (3.6 parts by weight; average molecular weight 4,000), styrene as a polymer monomer,
A mixture of stearyl methacrylate, butyl methacrylate and acrylic acid in a weight ratio of 66: 4: 20: 10 (10
0 parts by weight) and a 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 a polymer is generally 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 grafted wax component having a low molecular weight substance and a high molecular weight substance. This polymer had a molecular weight peak of 10,000 in a low molecular weight substance, and had a weight average molecular weight of 100,000 and an acid value of 10.

Example 1 <Preparation of Toner>

[0137]

[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, hydrophobic silica fine particles having an average particle diameter of 0.015 μm as a fluidity improving agent and hydrophobic alumina having an average particle diameter of 0.3 μm as spacer particles were respectively added to 100 parts by weight of the toner particles. 0.
3 parts by weight and 0.6 parts by weight were added, and the mixture was mixed for 2 minutes with a Henschel mixer and externally added to obtain a toner.

<Preparation of Carrier>

[0141]

[Table 2]

Spherical ferrite particles having an average particle size of 100 μm were used as the magnetic core particles. This ferrite particle 10
The coating agent having the composition shown in Table 2 was added to 00 parts by weight, and mixed using a heating and stirring device. After the solvent was dried and removed from the obtained mixture, heat treatment was carried out at 180 ° C. for 1 hour to obtain carrier particles having a coating layer.

10 g of the carrier obtained above was placed in a glass container, and toluene was added to dissolve the uncured resin.
Next, the toluene solution was discarded while the carrier was attracted from below the glass container with a magnet. After repeating this operation several times, the carrier was dried in an oven. The C content (carbon content) of the carrier before and after the toluene treatment (washing) was measured with a "carbon analyzer" (manufactured by Horiba), and the degree of curing was defined by the following formula. The obtained curing degree is shown in Table 2 above.

[0144]

[Equation 2]

<Preparation of Developer> The above toner and carrier were uniformly mixed to obtain a two-component developer having a toner concentration of 3.5% by weight.

(Example 2) A developer was obtained in the same manner as in Example 1 except that the curing temperature was changed to 200 ° C.

(Comparative Example 1) A developer was obtained in the same manner as in Example 1 except that the curing temperature was changed to 170 ° C.

[Evaluation of Developer] The developers of Examples and Comparative Examples were 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%. The evaluation results are shown in Table 3.

(B) Charge Amount 50,000 copies were made using a character original having an area ratio of black area 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. The evaluation results are shown in Table 3.

(C) 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 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%. The evaluation results are shown in Table 3.

(D) 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 3.

(E) Transfer Efficiency The toner amount in the toner hopper before the start of copying and the toner amount in the toner hopper after copying 50,000 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 50,000 sheets was measured and used as the toner recovery amount. From these values, the toner transfer efficiency was calculated by the following equation (i). Here, the original used for copying is a character original in which the area ratio of the black portion is 8%.

[0154]

(Equation 3)

The evaluation results are shown in Table 3.

(F) Amount of Adhered Substances on Surface of Particles of Carrier Due to Spent Copying is performed using a character original having an area ratio of black portion of 8%.
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 amount obtained by subtracting the elution amount of the coating layer of the carrier from the difference between the weight of the carrier initially placed in the beaker and the weight after evaporation of toluene is the amount of the toner component adhered to the particle surface of the carrier by the spent (spent amount). . The spent amount is represented by mg of the toner component attached to 1 g of the carrier. The evaluation results are shown in Table 3.

(G) Filming 50,000 copies were made using a character original having an area ratio of the black portion of 8%. The state of the drum in the copying machine at this point was visually observed and evaluated according to the following criteria. ◯: without filming x: with filming Table 3 shows the evaluation results.

[0158]

[Table 3]

[Discussion of Evaluation Results] The developers obtained in the examples have good chargeability, low fog density, and excellent transfer efficiency, as compared with the developers obtained in the comparative examples. Further, the amount of the deposits of the carrier on the particle surface of the carrier was about 3/5 that of the comparative example, and the toner scattering was not observed. The image density was also excellent. Furthermore, the developers of the examples did not cause filming.

[0160]

As described above, according to the present invention, there is provided a two-component developer containing no charge control agent, which is a main cause of spent during copying. The toner particles of the toner contained in this developer contain a fixing resin made of a composition containing at least one styrene-acrylic polymer. The at least one styrene-acrylic polymer has an anionic polar group and a side chain having 1 carbon atom.
The component having two or more alkyl groups and the grafted wax component each independently or in combination, and the styrene-acrylic polymer satisfies the following conditions: (a) peak of molecular weight of the polymer Is 4,000 to 30,
000, (b) the weight average molecular weight of the polymer is 70,000 to 200,000, and (c) the acid value of the polymer is 4 to 20. The magnetic powder is contained in the toner particles in a predetermined ratio. The core particles of the carrier contained in the developer are composed of a magnetic material having a specific composition, and the coating layer for coating the core particles is a resin composition containing a thermosetting resin. The degree is 85% or more. Further, spacer particles having a predetermined particle diameter are attached to the surface of the toner particles as needed.

In the toner of the developer of the present invention, since the wax is grafted to the fixing resin, the offset resistance is excellent, and the spent unlike the case of using the conventional release agent is hard to occur. Further, since the styrene-acrylic polymer has a component having an alkyl group having a carbon number of 12 or more in the side chain, the compatibility of the fixing resin and the wax is increased, so that the homogeneity of the fixing resin is further increased,
As a result, the variation in performance among the toner particles is reduced, so that the life of the toner can be extended. Further, by specifying the weight average molecular weight of the polymer, the peak of the molecular weight and the acid value, it is possible to improve both the spent resistance, the fixability, the pulverizability during toner production, and the charge stability under high humidity. it can.

The toner of such a developer has sufficient chargeability, and the toner particles and the carrier particles are also sufficiently bonded. Therefore, this developer does not generate spent during copying, toner does not scatter, transfer efficiency is sufficient, and a copy image having a required density can be stably obtained for a long time. Further, since the particles of the carrier of the developer of the present invention have the above coating layer, filming is prevented.

Such a two-component type developer 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 is a graph showing the absorbance of a methanol extract of a toner used in a developer of the present invention at wavelengths of 200 to 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

Front page continuation (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location G03G 9/107 9/113 G03G 9/08 365 9/10 321 351 352 (72) Inventor Tomohide Iida Osaka City Central Ward 1-22, Mita Kogyo Co., Ltd. (72) Inventor, Eiichi Tamura Chuo-ku, Osaka 1-2-2 Tamazo, Mita Kogyo Co., Ltd. (72) Inventor, Kazuhiko Fujii Chuo-ku, Osaka 1-2-2 Tamatsukuri Mita Industrial Co., Ltd.

Claims (8)

[Claims] 1. A two-component developer containing a toner and a carrier, wherein the toner contains toner particles, and the toner particles contain a fixing resin and a magnetic powder dispersed in the resin. The fixing resin is a composition containing at least one styrene-acrylic polymer, and the at least one styrene-acrylic polymer has an anionic polar group and an alkyl group having 12 or more carbon atoms in the side chain. A component having a group and a grafted wax component, independently or in combination, the styrene-acrylic polymer satisfies the following conditions, and (a) the molecular weight peak of the polymer is 4,000 to 30,
000, (b) the weight average molecular weight of the polymer is 70,000 to 200,000, (c) the acid value of the polymer is 4 to 20, and the magnetic powder is 100 weight% of the fixing resin. 0 for the department.
The carrier particles are contained in the toner particles in an amount of 1 to 5 parts by weight, and the carrier particles have core particles and a coating layer for coating the core particles, and the core particles are represented by the following formula (A). The magnetic material is: MOFe ₂ O ₃ (A) where M is Cu, Zn, Fe, Ba, Ni, Mg, M
The coating layer is at least one metal selected from the group consisting of n, Al and Co, the coating layer is a resin composition containing a thermosetting resin, and the coating layer has a curing degree of 85% or more. Is a two-component developer. 2. The extract obtained by extracting the toner with methanol has substantially no absorption peak in the region of 280 to 350 nm, and the absorbance in the region of 400 to 700 nm is substantially zero. Item 2. The developer according to Item 1. 3. The fixing resin is an anionic polar group,
The developer according to claim 1, comprising a styrene-acrylic polymer having a component having an alkyl group having 12 or more carbon atoms in a side chain and a grafted wax component in combination. 4. The fixing resin 100 comprises the magnetic powder.
The developer according to claim 1, which is contained in a ratio of 0.5 to 3 parts by weight with respect to parts by weight. 5. The volume-based average particle diameter of the toner particles is 5
2. The developer 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. 6. The core particles have a particle size of 50 to 150 μm.
The developer according to claim 1, which is m. 7. The core particle 10 has a weight of the coating layer.
0.001 to 2.5 parts by weight with respect to 0 parts by weight,
The developer according to claim 1. 8. The thermosetting resin is a modified or unmodified silicone resin, thermosetting acrylic resin, thermosetting styrene-acrylic resin, phenol resin, urethane resin, thermosetting polyester resin, epoxy resin, and The developer according to claim 1, which is at least one selected from the group consisting of amino resins.