JP3105745B2 - Two-component developer toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for a two-component developer, and more particularly to a toner having a high transfer efficiency and a desired density of a copied image over a long period of time even though it does not contain a charge controlling agent. The present invention relates to a two-component developer toner 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 developers for developing an electrostatic latent image on a photosensitive member. The two-component developer contains a toner containing a colorant such as carbon black and a fixing resin, and a magnetic carrier containing iron powder, ferrite particles and the like.

At the time of development, the toner is charged to a predetermined polarity by mixing the toner with a carrier, and then the mixture is conveyed to a photoreceptor in the form of a magnetic brush. The photoreceptor is rubbed by the magnetic brush, and toner adheres to the electrostatic latent image on the photoreceptor surface. In general, a charge control agent is contained in toner particles in order to keep the amount of adhered toner constant and to provide a predetermined amount of charge to the toner in order to provide a stable image. For the negatively charged toner, a negative charge controlling agent such as a metal-containing complex dye containing a metal such as chromium (for example, an azo-based dye) or a metal oxycarboxylate (for example, a metal salicylate) is used (see JP-A-Hei. JP-A-3-67268), and a positively chargeable toner uses an oil-soluble dye such as nigrosine, and a positive charge control agent such as an amine-based control agent.
No. 106249).

[0004] Many conventional charge control agents contain compounds containing heavy metals, such as chromium-containing complexes.
When these are used, 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 a form contained in a toner,
It would be more desirable to avoid the use of charge control agents containing these heavy metals. Further, since the charge controlling agent has a higher unit price than coloring materials such as a fixing resin and carbon black, which are materials constituting the toner, the unit price of the toner is increased despite its content of about several percent.
Therefore, development of a toner that does not contain such a heavy metal-containing charge control agent is desired.

In addition, in the conventional toner, a long time use causes spent to adhere to the toner particles on the surface of the carrier particles. Therefore, the charged state of the surface of the carrier particles is similar to the charged state of the surface of the toner particles. come. As a result, there is a disadvantage that toner scattering occurs and transfer efficiency is reduced.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned conventional problems.
An object of the present invention is to provide a toner for a two-component developer in which the toner has good charging performance even though it does not contain a charge control agent at all, so that the scattering of the toner is small and the image quality is excellent.

Another object of the present invention is to provide a two-component developer toner which does not cause spent even when used for a long period of time, thereby maintaining good image quality and stabilizing transfer efficiency. It is in.

[0008]

The two-component developer toner of the present invention comprises a fixing resin and toner particles containing a magnetic powder dispersed in the resin, and the fixing resin is anionic. A composition comprising a resin having a low molecular weight and a high molecular weight having a polar group, the content of the anionic polar group in the low molecular weight is less than the content of the anionic polar group in the high molecular weight, And the SP value (solubility parameter) of the low molecular weight material is smaller than the SP value of the high molecular weight material, and the magnetic powder is
The above object is achieved by being contained in the toner particles at a ratio of 0.1 to 5 parts by weight with respect to parts by weight.

In a preferred embodiment, the extract obtained by extracting the toner with methanol is 280 to 350.
substantially no absorption peak in the region of
The absorbance in the region from to 700 nm is substantially zero.

In a preferred embodiment, the magnetic powder is used in an amount of 0.5 to 3 based on 100 parts by weight of the fixing resin.
It is contained in parts by weight.

In a preferred embodiment, the toner particles have a volume-based average particle size of 5 to 15 μm, and the surface of the toner particles has a volume-based average particle size of 0.05 to 1.0 μm.
μm spacer particles are attached.

[0012]

The toner for a two-component developer of the present invention does not contain any charge controlling agent such as an azo dye or a metal complex of oxycarboxylic acid. Therefore, as described later, since a spent caused by the charge control agent does not occur, a high-quality image can be copied for a long period of time. Since this toner does not contain any charge control agent, such a charge control agent can be obtained from the toner by any chemical or physical means.
That is, no dye-based compound is detected. For example, in the toner of the present invention, these compounds are not detected by a chemical reaction. Alternatively, no absorption peak due to these compounds is detected from the organic solvent extract of the toner of the present invention. For example, when the toner of the present invention is extracted with an organic solvent, for example, methanol, the extracted liquid is 280-35.
Substantially no absorption peak in the region of 0 nm and 40
The absorbance in the range from 0 to 700 nm is substantially zero. Here, "having substantially no absorption peak" means that no absorption peak was detected in an 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 0.05. It means the following. Similarly, the fact that the absorbance is substantially zero means that the absorbance of an extract obtained by extracting 0.1 g of the 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 for by the following matter. First, a resin having an anionic polar group is used as the fixing resin in the toner particles, and second, a magnetic powder is contained in the toner particles at a predetermined ratio.

Further, in the present invention, the fixing resin is composed of a composition containing a resin having a low molecular weight having an anionic polar group and a resin having a high molecular weight, respectively. By making the content ratio smaller than the content ratio of the anionic polar group in the polymer and making the SP value of the low molecule smaller than the SP value of the polymer, the compatibility between the low molecule and the polymer is improved. Therefore, when the toner is pulverized, the shearing force concentrates on the relatively soft interface between the low molecular weight substances, and the pulverizability of the toner can be improved. In addition, there is no occurrence of poor charging of the toner.

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

The above is described in detail below.

The methanol extract 20 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 has no peak due to each charge control agent. That is, 280-35
Substantially no absorption peak in the region of 0 nm and 40
The absorbance in the range from 0 to 700 nm is substantially zero. On the other hand, the absorbance curve of a methanol extract of a toner containing an azo chromium complex dye as a charge controlling agent has a peak in the range of 400 to 700 nm, particularly 550 to 570 nm (FIG. 2). The absorbance curve of a methanol extract of a toner containing a metal complex as a charge control agent has a peak in the range of 280 to 350 nm (FIG. 3).

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

The carrier of the developer whose chargeability of the carrier is insufficient due to the generation of spent is extracted with methanol,
When the absorbance at 400 to 700 nm is examined, a peak attributable to the charge control agent is observed in that region. For example, when a toner containing an azo chromium complex salt dye whose absorption curve 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 spent occurred. In FIG. 4, a peak is recognized at the same position as the charge control agent in FIG. In the past, spent was thought to be caused by the toner fixing resin adhering to the carrier particle surface to form a resin film.However, due to the above fact, one of the main causes of spent is charged. It was found that the transfer of the carrier from the toner particles of the control agent to the surface of the particles occurred.

The inventors conducted the following experiment in order to further investigate the relationship between the charge control agent and spent. First, a toner having toner particles containing 1.5% by weight of an azo chromium complex dye as a charge control agent and a carrier were mixed to prepare a developer. FIG. 5 shows the relationship between the elapsed time when the mixing / stirring operation of the toner and the carrier of the developer is continued and the weight of the adhered substance adhered to the particle surface of the carrier due to spent. The weight of the deposit is shown in FIG. 5 as a percent spent, as a percentage of the total weight of the carrier with the deposit. FIG. 6 shows the relationship between the elapsed time and the charge amount of the toner. Further, the same measurement was performed on a developer containing a toner having toner particles not containing the charge control agent and a carrier. Fig. 5 also shows the results.
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. 5 and 6, it can be seen that the toner containing the charge control agent forms more deposits on the surface of the carrier particles due to spent compared to the toner not containing the charge control agent, and the degree of reduction in the charge amount is large.

The weight of the toner component adhering to the surface of the carrier particles is measured over time with the spent, and the measured value is plotted on the horizontal axis (shown as spent amount), and the amount of the charge control agent in the toner component is plotted on the vertical axis. The graph taken is shown in FIG. The dotted line indicates 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 precipitates in the early stage of use of the developer and adheres to the surface of the carrier particles. 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 change, the difference between the two is likely to widen further.

Further, the present inventors investigated the relationship between the components constituting the toner particles and the spent by mixing a charge control agent, a fixing resin, carbon black as a colorant and wax, and a carrier with each other. -The weight of the deposit on the particle surface of the carrier generated by the passage of time when stirring was measured. FIG. 8 shows the result. In FIG.
Open circles indicate the results of a test using a charge control agent, black circles indicate carbon black, squares indicate fixing resins, and triangles indicate results of tests using wax. FIG. 8 shows that the charge control agent is most likely to cause the carrier to adhere to the particle surface due to spent.

From the above facts, the poor charging due to spent of the conventional two-component magnetic developer can be 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 toner 21. When this developer is used, the toner component mainly composed of the charge control agent in the toner particles adheres to the surface of the carrier particle 1. Since the attached matter 201 formed by this spent is negatively charged, a toner having a positive charge with respect to the attached matter 201, that is, the opposite polarity toner 22 is formed. This reverse polarity toner 2
Since particles 2 are formed on the surface of the particles 1 of the carrier, toner scattering occurs and transfer efficiency is reduced.

As described above, the charge control agent is, as described above,
Since it may contain heavy metal, it is preferable not to contain it. Further, as described above, it causes a major cause of spent, causing toner scattering and a decrease in transfer efficiency. Contains no agents.

The instability of the charge amount due to the absence of the charge control agent, mainly the shortage of the charge amount, is caused by the fact that the fixing resin having an anionic polar group is first used for the toner as described above. Supplemented. Since the anionic polar group gives a negative charge to the fixing resin itself, the shortage of the charge amount of the toner particles is compensated. Since the polar group is present by bonding to the skeleton of the resin itself, it migrates to the surface of the carrier particles unlike the charge control agent, and does not cause spent. However, conversely, the chargeability near the surface of the toner particles is
Since it is not so large, the coupling between the toner particles and the carrier particles by the Coulomb force in the magnetic brush during development is insufficient. Therefore, when high-speed copying is performed, the scattering of the toner is not sufficiently suppressed because the binding to the carrier particles is weak. The inside of the copier is contaminated by the scattering of toner,
There is a disadvantage that so-called fogging occurs in the image of the copy.

In the present invention, as described above, the second requirement is that the magnetic powder is contained in the toner particles at a predetermined ratio, that is, 0.1 to 5 parts by weight based on 100 parts by weight of the fixing resin. Incorporation of the compound makes it possible 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. As described above, since a magnetic attraction force is generated in addition to the Coulomb force between the toner particles and the carrier particles, scattering of the toner is prevented. In general, the smaller the charge amount per toner particle, the more
Since the number of toner particles adhering to a given electrostatic latent image increases, the apparent development sensitivity increases.

The content of the magnetic powder in the toner particles is as follows:
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, so that the toner is not sufficiently bonded to the particles of the carrier, so that the toner is easily scattered. In other words, there is a drawback that a so-called fog occurs in the image of the copy. When the content of the magnetic powder exceeds 5 parts by weight, the bonding force between the carrier particles and the toner particles becomes too large, so that the toner does not sufficiently adhere to the electrostatic latent image,
As a result, the image density decreases.

Attempts have been made to incorporate (internally add) magnetic powder into toner particles for the purpose of improving the resolution of images and the like. For example, JP-A-56-1062
No. 49 discloses toner particles containing 10% by weight of ferrite, and JP-A-59-162563 discloses toner particles containing 5 to 35% by weight of magnetic fine powder. . However, in any case, since the amount of the magnetic powder is excessive, the image density of the obtained copy is low. JP-A-3-67268 discloses a toner in 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 adhere unevenly 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 prior arts, since the charge control agent is contained in the toner, problems such as generation of spent may occur.

Further, in the present invention, the fixing resin is composed of a composition containing a resin having a low molecular weight having an anionic polar group and a resin having a high molecular weight, respectively. By making the content ratio smaller than the content ratio of the anionic polar group in the polymer and making the SP value of the low molecule smaller than the SP value of the polymer, the compatibility between the low molecule and the polymer is improved. Therefore, when the toner is pulverized, the shearing force concentrates on the relatively soft interface between the low molecular weight substances, and the pulverizability of the toner can be improved. In addition, there is no occurrence of poor charging of the toner.
The detailed reason is as follows.

Even in the toner containing no charge controlling agent, the low molecular weight in the fixing resin having the low molecular weight and the high molecular weight selectively adheres to the particle surface of the carrier based on the analysis result of the deteriorated carrier. Turns out there are cases.
When the low molecular weight material in the resin has a relatively large amount of an acid value component (crosslinking component) serving as an anionic polar group, the low molecular weight material adheres to the particle surface of the carrier, thereby causing friction with the toner. The toner having the opposite polarity is generated by the charging, and as a result, the charging failure of the toner may occur. Therefore, by setting the acid value of the low molecular weight to be lower than that of the high molecular weight and adding a large amount of non-crosslinking components (groups other than hydrogen or free acid) to the low molecular weight, the generation of the reverse polarity toner is reduced. Prevents poor charging of toner. Also, as described above, the acid value of the low molecular weight is set lower than that of the high molecular weight,
At the same time, the pulverizability of the toner can be improved by setting the SP value of the polymer to be higher than the SP value of the low molecular material.

In the present invention, in order to further enhance 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 is increased by long-time copying, the transfer efficiency is increased because the toner can be easily transferred from the surface of the photoconductor. 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 carrier particles becomes higher, and the toner scattering and fog can be further reduced.

Fine particles having a particle size of about 0.015 μm have been used as an external additive as a conventional fluidity improver, but such particles form a sufficient gap between the photosensitive member and the toner particles. Therefore, it does not function as the above-mentioned spacer particle.

[0033]

Preferred embodiments of the present invention are described below. Hereinafter, in the present specification, "lower alkyl group"
Means 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 having an anionic polar group and a resin having a high molecular weight, respectively. Composition. Here, the high molecular weight refers to a resin having a molecular weight of 100,000 or more, and the low molecular weight refers to a resin having a molecular weight of less than 100,000. The ratio of the low molecular weight to the high molecular weight is preferably 40 to 75% by weight.

Further, the molecular weight peak of the low molecular weight resin is preferably 4,000 to 30,000. If the molecular weight peak of the low molecular weight compound is less than 4,000, improvement in spent resistance cannot be expected and durability tends to decrease. 30,000
If it exceeds 300, pulverizability tends to decrease.

The content ratio of the anionic polar group in the low molecular weight polymer and the high molecular weight polymer can be represented by an acid value. The acid value of the low molecular weight polymer is preferably 3 to 15, and the acid value of the high molecular weight polymer is 6
~ 25 is preferred. The ratio of the acid value of the high molecular weight to the acid value of the low molecular weight is preferably from 1: 1.2 to 1: 8. When the acid value of the low molecular weight compound exceeds the above range, and when the ratio of the acid value is below the above range, poor charging of the toner due to spent tends to occur, and conversely, the toner tends to scatter.

The resin has a weight average molecular weight of 70,000 to 2
100,000 is preferred. If it is less than 70,000, the obtained toner is excessively pulverized, so that the toner particles are easily broken. If it exceeds 200,000, the pulverizability of the toner is apt to be reduced.

To obtain a resin having a low molecular weight and a high molecular weight, a low molecular weight polymer is prepared as described below,
Next, a polymer for the polymer may be added to the polymer and polymerized, or a separately prepared low molecular and polymer may be mixed.

The resin used for 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 polar 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 preferred. As the monomer having a carboxylic acid group, an ethylenically unsaturated carboxylic acid is used, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, maleic acid, and fumaric acid, and carboxylic acids such as maleic anhydride. Monomers capable of forming groups or lower alkyl half esters of dicarboxylic acids such as maleic acid and fumaric acid may also be used. Examples of the monomer having a sulfonic acid group include styrene sulfonic acid, 2-acrylamide-
2-methylpropanesulfonic acid and the like. 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 include:
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 monomer having an anionic polar group and other monomers to be polymerized as required are selected so that the obtained polymer has the fixing property and the charging property required for the toner. One or more combinations of monomers having an ethylenically unsaturated bond are used. Such monomers include acrylic ester monomers, monovinyl aromatic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers. and so on.

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

[0044]

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 monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate,
Phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, β-
Examples include ethyl hydroxyacrylate, γ-hydroxypropyl acrylate, δ-hydroxybutyl acrylate, and β-hydroxyethyl methacrylate.

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

[0048]

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, etc., and Φ is a phenylene group. It is.

As such a monomer, styrene, 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):

[0052]

Embedded image

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

Such monomers include vinyl formate,
Examples include vinyl acetate and vinyl propionate.

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

[0056]

Embedded image

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, vinyl cyclohexyl ether and the like.

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

[0060]

Embedded image

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

Such monomers include butadiene,
There are isoprene and chloroprene.

The monoolefin monomer is represented by the following general formula (VI):

[0064]

Embedded image

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

Such monomers 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, ionomer There are resins and the like. 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, the resin has an anionic polar group in such a ratio that the acid value is 2 to 30, preferably 5 to 15. It is desirable to have. When a part or all of the anionic polar group is neutralized, it is preferable to have the anionic polar group in such a ratio as to have the above-mentioned acid value when it is present 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 the acid value is higher than the above range, the toner has a hygroscopic property. Absent.

A preferred fixing resin contains the above-mentioned monomer having an anionic polar group and at least one of acrylic monomers of the formula (I) as essential components. A copolymer containing the monomers of the formulas (II) to (VI) as optional components is used.

Each of the above monomers can be used alone or in combination of two or more 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 of the anionic polar group in the whole composition is in the above range.

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

A low molecular weight monomer and a polymerization initiator are mixed with a solvent (eg, toluene, xylene, etc.) in which both the monomer and the resin can be dissolved, and the mixture is stirred. This mixed solution was charged into a reaction vessel 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 the solution, a low molecular weight polymer is obtained. Next, the polymer monomer, the low molecular polymer 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 charged into a reaction vessel, and polymerization is carried out at 60 to 200 ° C. for 5 to 24 hours while thoroughly stirring with a stirring blade. Then, after degassing and drying the solution, a polymer having a low molecular weight and a high molecular weight is obtained. Get.

(Magnetic Powder) As the magnetic powder contained (internally added) to the toner particles, any of the magnetic powders conventionally used for one-component magnetic toners can be used. As a material of the magnetic powder, for example, triiron tetroxide (F
e ₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe ₂ O ₄ ), and iron oxide yttrium (Y ₃ Fe
₅ O ₁₂ ), cadmium iron oxide (CdFe ₂ O ₄ ), gadolinium iron oxide (Gd ₃ Fe ₅ O ₁₂ ), copper iron oxide (CuFe ₂
O ₄ ), lead iron oxide (PbFe ₁₂ O ₁₉ ), nickel iron oxide (NiFe ₂ O ₄ ), and neodymium iron oxide (NdFe).
O ₃ ), barium iron oxide (BaFe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe ₂ O ₄ ), iron manganese oxide (MnF
e ₂ O ₄ ), iron lanthanum oxide (LaFeO ₃ ), iron (F
e), cobalt (Co), nickel (Ni), and the like. A particularly preferred magnetic powder is particulate iron tetroxide (magnetite). Preferred magnetite is octahedral and has 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 diameter of the magnetic powder contained in the toner particles is generally 1.0 μm.
m, preferably 0.05 to 1.0 μm.

The content of the magnetic powder in the toner particles is as follows:
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, the toner is scattered during the development as described above, resulting in an insufficient image density and an insufficient fixing effect.

(Compounding agent in toner particles)
As described above, the toner contains the fixing resin and the magnetic powder as essential components, and may further contain, if necessary, a compounding agent which can be usually compounded in the toner.

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

As the coloring agent, for example, the following pigments can be used.

Black pigments: carbon black, acetylene black, lamp black, aniline black.

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

The 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-based resin, polypropylene, polyethylene, propylene-ethylene copolymer and the like can be used, and 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 pulverization classification method, a melt granulation method, a spray granulation method and a polymerization method. And is usually produced by a pulverization classification method.

For example, after the components for forming the toner particles are premixed with a mixer such as a Henschel mixer, the components are kneaded using a kneading device such as a twin-screw extruder, and after cooling, pulverized. , And classified into toner particles. As for the particle diameter of the toner particles, it is generally preferable that the volume-based average particle diameter (median diameter measured by a Coulter counter) is in the range of 5 to 15 μm, particularly 7 to 12 μm.

If necessary, a fluidity improver such as hydrophobic fumed silica particles may be adhered to the surface of the toner particles as an external additive to improve the fluidity of the toner. The primary particle diameter of the fluidity improver such as the silica particles is usually about 0.015 μm, and is about 0.15 μm per 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 flow improver particles are externally added. As the spacer particles, 0.05 to
Any organic or inorganic inert particles of 1.0 μm, preferably 0.07-0.5 μm, can be used. Materials for such inert particles include silica, alumina,
Titanium oxide, magnesium carbonate, acrylic resin, styrene resin, magnetic material and the like can be mentioned. The spacer particles can function as a fluidity improver and have the function of increasing the 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, in particular, fine iron tetroxide (magnetite) particles. The use of magnetic powder particles as spacer particles effectively acts on toner scattering as described above. The spacer particles are 10% by weight or less, preferably 0.1 to 10% by weight based on the total weight of the toner.
%, More preferably 0.1 to 5% by weight. If it is excessive, the density of the copied image becomes insufficient.
When magnetic powder is used as the spacer particles, the total amount of 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 decrease.

In order to externally add the fluidity improver and the spacer particles to the toner particles, for example, the fluidity improver and the spacer particles are sufficiently mixed, and the 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 any state of being held in contact with the particle surface or being fixed in a state where the particle is partially driven into the inside from the particle surface. Thus, 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 form a two-component developer.

As the magnetic carrier, a ferrite-based magnetic carrier is preferably used. Soft ferrite containing preferably at least one, and preferably two or more, metal components selected from the group consisting of Cu, Mg, Mn and Ni in addition to Fe, for example, sintered ferrite of copper-zinc-magnesium ferrite In particular, spherical particles are used. The surface of the magnetic carrier particles may not be coated, but is generally preferably coated with a silicone resin, a fluorine resin, an epoxy resin, an amino resin, a urethane resin, or the like. The particle size of the magnetic carrier particles is 30 to 200 μm, particularly 50 to 150 μm.
Is desirably within the range. The saturation magnetization of the carrier is 3
It is desirably in the range of 0 to 70 emu / g, particularly 45 to 65 emu / g.

The mixing ratio between the magnetic carrier and the toner is generally from 98: 2 to 90:10, especially from 97: 3 to 9
Preferably, the weight ratio is 4: 6.

A copy can be made by a general electrostatographic copying method using a two-component developer containing the toner of the present invention. For example, after uniformly charging the photoconductive layer on the photoconductor, image exposure is performed to form an electrostatic latent image, and then a two-component magnetic developer magnetic brush is brought into contact with the photoconductor to form an 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 transferred image is fused and pressed by a heat roll to perform fixing.

[0092]

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

Example 1 A. Preparation of Fixing Resin 5 parts by weight of methacrylic acid (MAA), 35 parts by weight of butyl acrylate (BA), 60 parts by weight of styrene (St), and a polymerization initiator were mixed in a soluble solvent and stirred. The obtained mixed solution was charged into a reaction vessel, and polymerization was carried out at 150 ° C. for 5 hours while sufficiently stirring with a stirring blade. Thereafter, the solution was degassed and dried to obtain a low molecular weight polymer. Next, 15 parts by weight of methacrylic acid, 25 parts by weight of butyl acrylate, 60 parts by weight of styrene, a polymerization initiator, a soluble solvent, and 100 parts by weight of the low molecular weight polymer obtained above were mixed and stirred.
The obtained mixed solution was put into a reaction vessel, and polymerization was carried out at 80 ° C./15 hours while stirring well with a stirring blade. Thereafter, the solution was degassed and dried to obtain a polymer having low molecular weight and high molecular weight. .

The low molecular weight SP value of the obtained styrene acrylic resin was 9.17. The SP value of the polymer was 9.36.

Table 1 summarizes the constitution of the obtained fixing resin.
Shown in

[0096]

[Table 1]

In Table 1, SP of the crosslinking component (MAA)
The value of 10.73 indicates that the SP value of the polymer obtained by polymerizing only methacrylic acid is 10.73, the SP value of the non-crosslinked component (BA), and the styrene component (St). The same applies to the SP value of ()). further,
The SP value of the high / low molecular weight is an SP value calculated based on the monomer amount shown in the above section A.

B. Preparation of Toner (Composition of Toner Particles) Fixing resin: 100 parts by weight of styrene acrylic resin obtained in the above section A Colorant: 10 parts by weight of carbon black Magnetic powder: 2 parts by weight of magnetite Biaxial extruder for each of the above components Then, the kneaded product was pulverized by a jet mill and classified by an air classifier to obtain toner particles having an average particle diameter of 10.0 μm.

[0099] This toner particles, an average particle diameter of 0.015μm hydrophobic silica fine particles as flow improver in a proportion of 0.3 parts by weight per 100 parts by weight of the toner particles, and the flat Hitoshitsubu diameter 0.3 μm alumina fine particles were added (externally added) at a ratio of 0.6 parts by weight to 100 parts by weight of the toner particles, and mixed with a Henschel mixer for 2 minutes.
A toner was obtained.

Comparative Example 1 A. Preparation of Fixing Resin 15 parts by weight of methacrylic acid, 10 parts by weight of butyl acrylate, 75 parts by weight of styrene, and a polymerization initiator were mixed with a soluble solvent and stirred. The obtained mixed solution was charged into a reaction vessel, and polymerization was carried out at 150 ° C. for 5 hours while sufficiently stirring with a stirring blade. Thereafter, the solution was degassed and dried to obtain a low molecular weight polymer.

Next, 5 parts by weight of methacrylic acid, 20 parts by weight of butyl acrylate, 75 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 vessel, and polymerization was carried out at 80 ° C./15 hours while sufficiently stirring with a stirring blade. Thereafter, the solution was degassed and dried to obtain a polymer.

The low molecular weight SP value of the obtained styrene acrylic resin was 9.42. The SP value of the polymer was 9.23.

Table 1 summarizes the constitution of the obtained fixing resin.
Shown in

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

Comparative Example 2 A. Preparation of Fixing Resin 13 parts by weight of methacrylic acid, 7 parts by weight of butyl acrylate, 80 parts by weight of styrene, and a polymerization initiator were mixed with a soluble solvent and stirred. The obtained mixed solution was charged into a reaction vessel, and polymerization was carried out at 150 ° C. for 5 hours while sufficiently stirring with a stirring blade. Thereafter, the solution was degassed and dried to obtain a low molecular weight polymer.

Next, 10 parts by weight of methacrylic acid, 5 parts by weight of butyl acrylate, 85 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 vessel, and polymerization was carried out at 80 ° C./15 hours while sufficiently stirring with a stirring blade. Thereafter, the solution was degassed and dried to obtain a polymer.

The low molecular weight SP value of the obtained styrene acrylic resin was 9.40. The SP value of the polymer was 9.37.

Table 1 summarizes the constitution of the obtained fixing resin.
Shown in

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

[Evaluation of Toner] The toners obtained in Example 1 and Comparative Examples 1 and 2 were each given an average particle diameter of 100 μm.
m 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. The test was performed using an electronic copier (trade name "DC-46") manufactured by Mita Kogyo Co., Ltd.
85 ") (a modified copier for easily sampling an evaluation sample).

(A) Transfer Efficiency The amount of toner in the toner hopper before copying was started and the amount of toner in the toner hopper after copying a predetermined number of sheets were measured, and the toner consumption was calculated from the difference. On the other hand, the amount of toner collected in the cleaning step during copying of a predetermined number of sheets was measured, and this was defined as the amount of collected toner. From these values,
The transfer efficiency of the toner was calculated by the following equation (i). Here, the original used for copying is a character original having a black area ratio of 8%. This evaluation was performed in order to perform each of the evaluation tests described in (b) and below.

[0112]

(Equation 1)

(B) Image Density (ID) Copying is performed using a character original having a black area ratio of 8%.
Copying was continued until the transfer efficiency was less than 70%. Every 5,000 sheets, the density of the solid black portion in the copied image was measured using a reflection densitometer (model number “TC-6D” manufactured by Tokyo Denshoku Co., Ltd.), and the average value was defined as the image density (ID). . Here, the original used for sampling every 5,000 sheets is an original having a black area including a solid black area and an area ratio of 15%. Table 2 shows the evaluation results.

(C) Fog density (FD) Copying is performed using a character manuscript having a black area ratio of 8%.
Copying was continued until the transfer efficiency was less than 70%. The density of the non-image portion of 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 before copying (base paper) with a reflection densitometer was calculated, and the highest value was defined as the fog density (FD). Here, the original used for sampling 5,000 sheets is an original having a black area ratio of 15% including a solid black part. Table 2 shows the evaluation results.

(D) Resolution A copy is performed using a character original having a black area ratio of 8%.
At the time of copying 50,000 sheets (if the transfer efficiency has become less than 70% by that time), a prescribed chart document (document using a plurality of patterns with a predetermined number of parallel straight lines drawn per mm) , And the copied image was visually determined. Table 2 shows the evaluation results.

(E) Amount of Charge Copying is performed using a character original having a black area ratio of 8%.
Copying was continued until the transfer efficiency was less than 70%. The charge amount of 200 mg of the developer was measured every 5,000 sheets using a “blow-off powder charge amount measuring device” (manufactured by Toshiba Chemical Co., Ltd.), and the average value of the charge amount per gram of the toner was calculated. Table 2 shows the evaluation results.

(F) Amount of attachment to the particle surface of the carrier due to spent The copy was performed using a character manuscript having an area ratio of black portions of 8%.
The developer was sampled when 50,000 copies were made (if the transfer efficiency was less than 70% by that time). Place the developer on a 400 mesh sieve,
The toner was suctioned from below with a blower to separate the toner and the carrier. 5 g of the carrier remaining on the sieve was placed in a beaker, and toluene was further added to the beaker to dissolve the toner component attached to the surface of the carrier particles by spent. Thereafter, the toluene solution was discarded while the carrier was attracted by a magnet from under the beaker. After repeating this several times until the toluene became colorless, the weight of the residue obtained by evaporating the toluene adhering to the carrier in an oven was measured. The difference between the weight of the carrier initially placed in the beaker and the weight after toluene evaporation is the amount (spent amount) of the toner component attached to the particle surface of the carrier by the spent. The spent amount is represented by mg of the toner component attached per gram of the carrier. Table 2 shows the evaluation results.

(G) Toner Scattering Copying is performed using a character original having a black area ratio of 8%.
Copying was continued until the transfer efficiency was less than 70%. At this time, the toner scattering state in the copying machine was visually observed and evaluated according to the following criteria. ：: no toner scattering x: toner scattering The evaluation results are shown in Table 2.

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

(I) Pulverizability The toner was supplied to a jet mill and pulverized at a constant pressure, and the toner supply speed (g / min) at that time was evaluated according to the following criteria. ◎: 120 g / min or more ：: 100 g / min or more and less than 120 g / min ×: less than 100 g / min The evaluation results are shown in Table 2.

[0121]

[Table 2]

[Consideration of Evaluation Results] The toner of Example 1
The image density, fog and resolution were very stable, and toner scattering was good. The grindability is also low molecular weight SP
It can be seen that the values are higher than those of Comparative Example 2 in which the polymer and the low molecular weight are equivalent. Regarding the durability, it can be seen that the low molecular acid value is higher than that of Comparative Example 1 which is higher than the high molecular acid value.

[0123]

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

Therefore, the chargeability of the toner is sufficient, the toner is not scattered at the time of copying, the transfer efficiency is sufficient, and a copy image of 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 constituting the resin is set to be lower than that of the high molecular weight, and the non-crosslinking component is contained in the low molecular weight in a large amount. Is higher than the SP value of the low molecular weight material, so that the compatibility between the low molecular weight material and the high molecular weight material is reduced. Can be increased.

Further, with the above configuration, the occurrence of toner of the opposite polarity can be reduced, the occurrence of charging failure can be further suppressed, and the durability can be further improved.

[0127] Such a two-component developer toner is suitably used in an electronic image forming apparatus such as an electrostatic copying machine or a laser beam printer.

[Brief description of the drawings]

FIG. 1 shows the wavelength 2 of the 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 dye (2: 1 type) as charge control agent
200-7 wavelength of methanol extract of toner containing
It is a graph which shows the light absorbency in 00 nm.

FIG. 3 shows a wavelength of 200 to 700 nm of a methanol extract of a toner containing a salicylic acid metal complex as a charge control agent.
5 is a graph showing the absorbance at a time.

FIG. 4 Chromium complex dye (2: 1 type) as charge control agent
Is used for a two-component magnetic developer, and the carrier when charge failure due to spent occurs,
Methanol extraction was performed, and the wavelength of this extract was 200-70.
It is a graph at the time of measuring the light absorbency in 0 nm.

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

FIG. 6 shows the mixing / stirring time when the operation of mixing and stirring the toner containing the charge controlling agent and the magnetic carrier or the mixing and stirring of the toner not containing the charge controlling agent and the magnetic carrier is continued. 4 is a graph showing a relationship with a charge amount.

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

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

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

[Explanation of symbols]

 1 Carrier particles 2 Toner 22 Reverse polarity toner

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Norio Kubo 1-2-28 Tamazo, Chuo-ku, Osaka-shi Mita Kogyo Co., Ltd. (72) Inventor Kazuya Nagao 1-2-28 Tamazo-ku, Chuo-ku, Osaka Mita Inside Industrial Co., Ltd. (72) Inventor Terumichi Asano 1-2-2, Tamazo, Chuo-ku, Osaka Mita Industrial Co., Ltd. (56) References JP-A-5-173366 (JP, A) JP-A-6-118701 (JP, A) JP-A-6-194873 (JP, A) JP-A-2-23569 (JP, A) JP-A-4-359260 (JP, A) JP-A-3-42674 (JP, A) JP-A-4-110860 (JP, A) JP-A-57-30848 (JP, A) JP-A-60-254157 (JP, A) JP-A-4-235565 (JP, A) JP-A-4-240658 (JP JP, A) JP-A-63-217362 (JP, A) JP-A-63-217364 JP, A) JP flat 2-63065 (JP, A) JP flat 3-257461 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) G03G 9/08

Claims (4)

(57) [Claims] 1. A two-component developer toner comprising a fixing resin and toner particles containing magnetic powder dispersed in the resin, wherein each of the fixing resins has an anionic polar group. A composition comprising a resin having a low molecular weight and a high molecular weight, wherein the content of the anionic polar group in the low molecular weight is less than the content of the anionic polar group in the high molecular weight, and the low molecular weight The SP value of the polymer is smaller than the SP value of the polymer, and the magnetic powder is used in an amount of 0.1 to 100 parts by weight of the fixing resin.
Contained in the toner particles at a ratio of 1 to 5 parts by weight,
A toner for two-component developer does not contain a charge control agent, and when extracted with methanol
Extract substantially absorbs in the 280-350 nm region
No peak and in the region of 400 to 700 nm
For two-component developers, the absorbance of which is substantially zero
Ner . 2. The fixing device according to claim 1, wherein the magnetic powder is
The toner according to claim 1, wherein the toner is contained in a ratio of 0.5 to 3 parts by weight based on part by weight. 3. The toner according to claim 1, wherein the volume-based average particle size 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 adhere to the surface of the toner particles. 4. The low molecular weight anionic polar group,
The anionic polar group of the polymer is a carboxylic acid
The toner according to claim 1, which is a base.