JPH0876409A - Toner for binary system developer - Google Patents

Abstract

PURPOSE: To provide a toner that contains no electrostatic charge control agent being mainly attributable to a spent at time of copying, which is sufficient enough in electrifiability, no scattering at time of copying, also adequate enough in transfer efficiency, thereby stably securing the required density copied image for hours, and further reduces the possible growth of a reverse-polar toner, whereby the occurrence of electrostatic charge failure in the toner is made yet more checkable. CONSTITUTION: This is a toner for a binary system developer containing toner grains inclusive of fixing resin and magnetic powder dispersed in this resin. This fixing resin in the tone grains consists. of a composition containing a low molecular body with an anionic polar group and resin with a high molecular body each, and an acid number of the low molecular body is smaller as compared with that of the high molecular body. The magnetic powder is contained in the toner grains at the rate of 5 pt.wt from 0.1 to 100 pt.wt in the fixing resin. Toner grain size of this toner is 5 to 15μm, and it is recommendable that a spacer grain of 0.05 to 1.0μm in volume reference mean grain size is stuck to this toner grain surface.

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 (for example, azo dyes) and oxycarboxylic acid metal complexes (for example, 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 a two-component developer which does not cause spent even during long-term use and, as a result, maintains good image quality and has stable transfer efficiency. It is in.

[0008]

A two-component developer toner of the present invention comprises a fixing resin and toner particles containing magnetic powder dispersed in the resin, each of the fixing resin being anionic. A composition comprising a resin having a low molecular weight substance having a polar group and a high molecular weight substance, wherein the acid value of the low molecular weight substance is smaller than the acid value of the high molecular weight substance, and the magnetic powder is By being contained in the toner particles in a ratio of 0.1 to 5 parts by weight with respect to 100 parts by weight of the fixing resin,
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 low molecular weight compound has an acid value of 3 to 15, the high molecular weight compound has an acid value of 6 to 25, and the low molecular weight compound has an acid value of 3 to 15. The acid value ratio of is from 1: 1.2 to 1: 8.

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.
Spacer particles of μm are attached.

[0013]

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 described later, the spent due to the charge control agent is not generated, so that a high quality image can be copied 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 absorption peaks due to these compounds are detected in the organic solvent extract of the toner of the present invention. For example, when the toner of the present invention is extracted with an organic solvent such as methanol, the extract liquid is 280 to 350.
has substantially no absorption peak in the nm region, and 400
The absorbance in the region of ˜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 that peak is 0.05 or less. It means that. Similarly, if the absorbance is substantially zero,
The absorbance of an extract obtained by extracting 0.1 g of toner with 50 ml of methanol is 0.05 or less.

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 by the following matters. The first is to use a resin having an anionic polar group as the fixing resin in the toner particles, and the second is to contain the magnetic powder in a predetermined ratio in the toner particles.

Further, in the present invention, the fixing resin is composed of a composition containing a resin having a low molecular weight substance and a high molecular weight substance each having an anionic polar group, and the acid value in the low molecular weight substance is high. By setting the acid value smaller than the acid value in the body, the charging failure of the toner can be further reduced.

Further, if necessary, by attaching spacer particles having a predetermined particle size to the surface of the toner particles,
The transfer efficiency from the photoconductor to the transfer paper is improved.

The above will be described in detail below.

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

The absorption due to the charge control agent is observed in the methanol extract of the toner containing the 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 deposit is a percentage of the total weight of the carrier having the deposit and is shown in FIG. 5 as the percentage of spent. Further, FIG. 6 shows the relationship between the elapsed time and the toner charge amount. Further, the same measurement was performed for the developer containing the toner having the toner particles not containing the charge control agent and the carrier. The results are also shown in Figure 5.
And 6 are shown. In FIGS. 5 and 6, the black circle plots show the measured values of the toner containing the charge control agent, and the white circle plots show the measured values of the toner without the charge control agent. From FIGS. 5 and 6, it can be seen that the toner containing the charge control agent has a larger amount of deposits on the particle surface of the carrier due to the spent and the degree of decrease in the charge amount is larger than that of the toner containing no charge control agent.

The weight of the toner component adhering to the surface of the particles of the carrier was measured 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 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.

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 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 the fixing resin having an anionic polar group in the toner as described above. Will be supplemented. Since the fixing resin itself is provided with a negative charge by the anionic polar group, the insufficient charge amount of the toner particles is compensated. Since this polar group exists by binding to the skeleton of the resin itself, it does not migrate to the particle surface of the carrier like a charge control agent and cause spent. However, conversely, the chargeability near the surface of the toner particles is
Since it is not so large, the coupling between the toner particles and the carrier particles by the Coulomb force in the magnetic brush at the time of development is 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. Contamination of the inside of the copying machine due to toner scattering,
There is a drawback that so-called fog occurs in the image of the copy.

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

The content of the 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. When the content of the magnetic powder exceeds 5 parts by weight, the binding force between the carrier particles and the toner particles becomes too large, so that the toner does not adhere sufficiently to the electrostatic latent image,
As a result, the image density becomes low.

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

Further, in the present invention, the fixing resin is composed of a composition containing a resin having a low molecular weight substance and a high molecular weight substance each having an anionic polar group, and the acid value in the low molecular weight substance is high. By setting the acid value smaller than the acid value in the body, the charging failure of the toner can be further reduced. The detailed reason for this is as follows.

Even in the toner containing no charge control agent, from the analysis result of the deteriorated carrier, the low molecular weight substance in the fixing resin having the low molecular weight substance and the high molecular weight substance selectively adheres to the particle surface of the carrier. It turned out that there are cases. When the low molecular weight substance in the resin has a relatively large amount of acid value component (crosslinking component) which becomes an anionic polar group, the low molecular weight substance adheres to the particle surface of the carrier, which causes friction with the toner. There is a possibility that toner of opposite polarity may be generated by the charging, resulting in defective charging of the toner.

For example, considering the charge series of styrene-acrylic resin, the acrylic acid component tends to be negatively charged. This acrylic acid component is generally used as a fixing resin material for toner, and is included in the low molecular weight material of the fixing resin. When a relatively soft low-molecular substance adheres to the particle surface of the carrier, if many of the adhered components have a strong negative charge tendency, the toner charged by friction with it is oppositely charged (charged to the positive side). It is considered that the charging becomes easier and a charging failure occurs.

For this reason, the acid value of the low molecular weight substance is set lower than that of the high molecular weight substance. In other words, by containing a large amount of non-crosslinking components (groups that are not hydrogen or free acid) in low-molecular weight substances, it is possible to reduce the generation of reverse polarity toner, prevent toner charging defects, and improve durability. can do.

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 fluidity improving agent for toner, and 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.

[0036]

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 contains a resin having a low molecular weight substance and a polymer having an anionic polar group. The acid value of the low molecular weight substance is smaller than that of the high molecular weight substance. Here, the high molecular weight means a resin having a molecular weight of 100,000 or more, and the low molecular weight means a resin having a molecular weight of less than 100,000. The ratio of low molecular weight to high molecular weight is preferably 40 to 75% by weight.

The molecular weight peak of the low molecular weight substance is 4,000 to 3
10,000 is preferable. The low molecular weight molecular weight peak is 4,
If it is less than 000, improvement in spent resistance cannot be expected, and durability tends to decrease. If it exceeds 30,000, the pulverizability tends to decrease.

The weight average molecular weight of the resin is 70,000-2.
0,000 is preferable. If it is less than 70,000, the obtained toner is over-pulverized, so that the toner particles are easily broken, and if it exceeds 200,000, the pulverizability of the toner is likely to be deteriorated.

The acid value of the low molecular weight substance is set to be smaller than that of the high molecular weight substance, and particularly the acid value of the low molecular weight substance is 3 to.
15 is preferable, and the acid value of the polymer is preferably 6 to 25. The ratio of the acid value of the polymer to the acid value of the low molecule is preferably 1: 1.2 to 1: 8. When the acid value of the low molecular weight substance exceeds the above range, and when the ratio of the above acid values is below the above range, poor charging of the toner is likely to occur.

In order to obtain a resin having a low molecular weight substance and a high molecular weight substance, a low molecular weight polymer is prepared as described below,
Then, a monomer for a polymer may be added to this and polymerized, or the separately prepared low-molecular substance and the polymer may be mixed.

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

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

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

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

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

[0047]

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.

The monovinyl aromatic monomer is represented by the following general formula (II):

[0051]

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):

[0055]

[Chemical 3]

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

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

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

[0059]

[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):

[0063]

[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):

[0067]

[Chemical 6]

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

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

Specific examples of the resin having an anionic polar group which is a (co) polymer obtained by polymerizing the above monomers include styrene-acrylic acid copolymer, styrene-maleic acid copolymer, and ionomer. Resin etc. further,
A polyester resin having an anionic polar group can be used.

When such an anionic polar group is present in the form of a free acid, such a resin has an anionic polar group in a ratio such that the acid value is 2 to 30, preferably 5 to 15. Is desirable. When part or all of the anionic polar group is neutralized, it is preferable to have the anionic polar group in such a proportion that it has the above-mentioned acid value when it exists in the form of a free acid. When the acid value of the resin, that is, the concentration of the anionic polar group, is lower than the above range, the chargeability of the toner is insufficient, and when it is higher than the above range, the toner has hygroscopicity, which is preferable. Absent.

A suitable fixing resin contains at least one kind of the above-mentioned monomer having an anionic polar group and the acrylic monomer of the formula (I) as an essential component, and if necessary, the formula Copolymers containing the monomers of formulas (II) to (VI) as optional components are 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 the fixing resin used in the present invention, a resin composition containing the above resin is used.
In addition to the above resin, a polymer having no anionic polar group may be contained. In that case, the content ratio of the anionic polar group in the entire composition is preferably within the above range.

(Method for Producing Resin Used for Fixing Resin) The resin having a low molecular weight substance and a high molecular weight substance used in the present invention can be produced as follows.

The low molecular weight monomer and the polymerization initiator are mixed in a solvent (for example, toluene, xylene, etc.) in which both the monomer and the resin can be dissolved, and the mixture is stirred. This mixed solution was put into a reaction kettle and stirred well with a stirring blade,
Polymerization is performed at 0 to 250 ° C. for 3 to 10 hours, and after degassing and drying of the solution, a low molecular weight polymer is obtained. Next, the monomer for polymer, the polymer of low molecular weight obtained above and the polymerization initiator are mixed and stirred in a solvent capable of dissolving both the monomer and the resin. 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. After that, the solution is degassed and dried, and then a polymer having a low molecular weight substance and a high molecular weight substance is obtained. obtain.

(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, toner is scattered during development, resulting in insufficient image density and insufficient fixing effect.

(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 agents include colorants and release agents.

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

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

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

The above-mentioned pigment is contained in the toner particles 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 low molecular weight olefin resins are used. As the olefin resin, polypropylene, polyethylene, propylene-ethylene copolymer and the like can be used, but polypropylene is particularly preferable.

(Preparation of Toner) 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 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 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 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, a soft ferrite containing at least one metal component selected from the group consisting of Cu, Mg, Mn and Ni in addition to Fe, preferably two or more, for example, a sintered ferrite of copper-zinc-magnesium ferrite. The following particles 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, particularly 50 to 150 μm.
It is desirable to be in the range of. Carrier saturation magnetization is 3
It is preferably in the range of 0 to 70 emu / g, particularly 45 to 65 emu / g.

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

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

[0094]

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

(Example 1) A. Preparation of Fixing Resin 3 parts by weight of methacrylic acid, 17 parts by weight of butyl acrylate, 80 parts by weight of styrene, and a polymerization initiator were mixed in a soluble solvent and stirred. The obtained mixed solution was put into a reaction kettle and sufficiently stirred with stirring blades to carry out polymerization at 160 ° C./6 hours, and then the solution was degassed and dried to obtain a low molecular weight polymer.

Next, 10 parts by weight of methacrylic acid, 20 parts by weight of butyl acrylate, 70 parts by weight of styrene, a polymerization initiator, a soluble solvent and the low molecular weight polymer 10 obtained above.
0 parts by weight were mixed and stirred. The obtained mixed solution was put into a reaction kettle and polymerized at 90 ° C./17 hours while stirring well with a stirring blade, and then the solution was degassed and dried to obtain a polymer having a low molecular weight substance and a high molecular weight substance. .

The acid value ratio of the low molecular weight material and the high molecular weight material in the obtained resin (acid value of the high molecular weight material / acid value of the low molecular weight material) was 15 /
It was 5.

The acid value is measured by dissolving the obtained toner in a solvent (for example, a mixed solvent of methanol and THF). Next, after removing carbon black, wax and the like with a centrifuge, low molecular weight substances and high molecular weight substances were separated and the acid value of each was measured. B. Preparation of Toner (Composition of Toner Particles) Fixing Resin: Resin Obtained in Section A 100 Parts by Weight Colorant: Carbon Black 10 Parts by Weight Magnetic Powder: Magnetite 2 Parts by Weight The above components are melted by a twin-screw extruder. After kneading, the kneaded material was pulverized with a jet mill and classified with an air classifier to obtain toner particles having an average particle size of 10.0 μm.

Hydrophobic silica fine particles having an average particle diameter of 0.015 μm are added to the toner particles at a ratio of 0.3 parts by weight to 100 parts by weight of the toner particles, and the average particle diameter is 0. Alumina fine particles 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 by a Henschel mixer for 2 minutes,
Toner was obtained.

(Example 2) A. Preparation of Fixing Resin 6 parts by weight of methacrylic acid, 19 parts by weight of butyl acrylate, 75 parts by weight of styrene, and a polymerization initiator were mixed in a soluble solvent and stirred. The obtained mixed solution was put into a reaction kettle and sufficiently stirred with stirring blades to carry out polymerization at 160 ° C./6 hours, and then the solution was degassed and dried to obtain a low molecular weight polymer.

Next, 10 parts by weight of methacrylic acid, 20 parts by weight of butyl acrylate, 70 parts by weight of styrene, a polymerization initiator, a soluble solvent and 100 parts by weight of the polymer obtained above were mixed and stirred. The obtained mixed solution was put into a reaction kettle and polymerized at 90 ° C./17 hours while stirring well with a stirring blade, and then the solution was degassed and dried to obtain a polymer having a low molecular weight substance and a high molecular weight substance. .

The acid value ratio of the low molecular weight material and the high molecular weight material in the obtained resin (acid value of the high molecular weight material / acid value of the low molecular weight material) was 15 /
It was 10.

B. Preparation of Toner Example 1 except that the resin obtained in Section A above was used.
A toner was obtained in the same manner as in.

(Comparative Example 1) A. Preparation of Fixing Resin 8 parts by weight of methacrylic acid, 19 parts by weight of butyl acrylate, 73 parts by weight of styrene, and a polymerization initiator were mixed in a soluble solvent and stirred. The obtained mixed solution was put into a reaction kettle and sufficiently stirred with stirring blades to carry out polymerization at 160 ° C./6 hours, and then the solution was degassed and dried to obtain a low molecular weight polymer.

Next, 6 parts by weight of methacrylic acid, 24 parts by weight of butyl acrylate, 70 parts by weight of styrene, a polymerization initiator, a soluble solvent and 100 parts by weight of the polymer obtained above were mixed and stirred. The obtained mixed solution was put into a reaction kettle and polymerized at 90 ° C./17 hours while stirring well with a stirring blade, and then the solution was degassed and dried to obtain a polymer having a low molecular weight substance and a high molecular weight substance. .

The acid value ratio of the low molecular weight compound and the high molecular weight substance in the obtained resin (acid value of the high molecular weight substance / acid value of the low molecular weight substance) was 10 /.
It was 15.

B. Preparation of Toner Example 1 except that the resin obtained in Section A above was used.
A toner was obtained in the same manner as in.

[Evaluation of Toner] Each of the toners obtained in Examples 1 and 2 and Comparative Example 1 had an average particle size of 100 μm.
Ferrite carrier was added and mixed uniformly to obtain a two-component developer having a toner concentration of 3.5%. Next, the developer was evaluated for the following items. What was used for the test was an electronic copying machine (trade name "DC-468" manufactured by Sanda Kogyo Co., Ltd.
5)) modified machine (a modified copying machine for easily sampling the evaluation sample).

(A) 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 each evaluation test under item (b).

[0110]

[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%. The evaluation results are shown in Table 1.

(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 on 5,000 sheets is a document in which the area ratio of black portions including black solid portions is 15%. The evaluation results are shown in Table 1.

(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 (when the transfer efficiency is less than 70% by then), the specified chart original (1
Copying was performed using a document using a plurality of patterns in which a predetermined number of parallel straight lines were drawn per mm), and the copied image was visually judged. The evaluation results are shown in Table 1.

(E) Charge Amount A black manuscript having an area ratio of 8% is used for copying.
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. The evaluation results are shown in Table 1.

(F) Amount of Adhered Substances on Surface of Particles of Carrier Due to Spent Copies were performed using a character original having an area ratio of black portion of 8%.
The developer was sampled at the time of copying 50,000 sheets (when the transfer efficiency was less than 70% by that time). Place the developer on a 400 mesh sieve,
The toner and the carrier were separated by sucking from below with a blower. 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. The evaluation results are shown in Table 1.

(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. A: No toner scattering X: Toner scattering evaluation results are shown in Table 1.

(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.
The evaluation results are shown in Table 1.

[0118]

[Table 1]

[Consideration of Evaluation Results] The toners of Examples 1 and 2 have very stable image density, fog, and resolution.
The toner scattering was also good. Also regarding durability,
It can be seen that the acid value of the low molecular weight substance is higher than that of Comparative Example 1 which is higher than that of the high molecular weight substance.

[0120]

According to the present invention, a toner containing no charge control agent, which is a main cause of spent during copying, is provided. The toner particles of this toner contain a fixing resin having an anionic polar group, and the toner particles contain magnetic powder at a predetermined ratio. Further, spacer particles 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.

Further, according to the present invention, the acid value of the low molecular weight substance constituting the resin is set lower than that of the high molecular weight substance, and the non-crosslinking component is contained in the low molecular weight substance in a large amount. As a result, it is possible to reduce the adhesion of low molecular weight substances to the carrier and prevent the generation of toner of the opposite polarity, and it is possible to further improve the durability.

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

[Brief description of drawings]

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

Fig. 2 Chromium complex salt dye (2: 1 type) as charge control agent
Wavelength of methanol extract of toner containing
It is a graph which shows the light absorbency in 00 nm.

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 Chromium complex salt dye (2: 1 type) as a charge control agent
A toner containing a toner is used for a two-component magnetic developer, and a carrier when a charging failure due to a spent occurs,
Methanol extraction was performed and the wavelength of this extract was 200-70.
It is a graph when the light absorbency in 0 nm 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 the amount of spent.

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 (72) Inventor Norio Kubo 1-22-28 Tamazo, Chuo-ku, Osaka Mita Kogyo Co., Ltd. (72) Kazuya Nagao 1-2-2 Tamazo, Chuo-ku, Osaka Mita Kogyo Incorporated (72) Inventor, Teruma Asano 1-22 Tamatsukuri, Chuo-ku, Osaka Mita Industrial Co., Ltd.

Claims (5)

[Claims] 1. A two-component developer toner comprising a fixing resin and toner particles containing magnetic powder dispersed in the resin, wherein the fixing resin has a low anionic polar group. A composition containing a resin having a molecular body and a polymer, wherein the low molecular weight acid value is smaller than the high molecular weight acid value,
A two-component developer toner, wherein the magnetic powder is contained in the toner particles in a proportion of 0.1 to 5 parts by weight with respect to 100 parts by weight of the fixing resin. 2. Extraction liquid when extracted with methanol is 2
The toner according to claim 1, which has substantially no absorption peak in the region of 80 to 350 nm, and has an absorbance of substantially zero in the region of 400 to 700 nm. 3. The acid value of the low molecular weight substance is 3 to 15, the acid value of the high molecular weight substance is 6 to 25, and the ratio of the acid value of the high molecular weight substance to the acid value of the low molecular weight substance. The toner according to claim 1, wherein: is from 1: 1.2 to 1: 8. 4. 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. 5. 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.