JP3287716B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for developing an electrostatic image formed by electrophotography or electrostatic printing.

[0002]

2. Description of the Related Art An electrophotographic method is disclosed in U.S. Pat.
A number of methods are known, as described in Japanese Patent Publication No. 7,691, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-24748, but generally, a photoconductive substance is used. An electric latent image is formed on the photoreceptor by various means, then the latent image is developed using toner, and if necessary, a toner image is transferred to a transfer material such as paper. The toner is fixed by pressurization or solvent vapor to obtain a copy, and the remaining toner not transferred onto the photoreceptor is cleaned by various methods, and the above-described steps are repeated.

As a developing system, a one-component developing system is preferably used from the viewpoint of miniaturization, weight reduction and maintenance-free of the apparatus.

Among them, a toner carrier and an electrostatic latent image carrier are arranged at a certain interval, and a thin layer of magnetic toner which does not come into contact with the latent image carrier is formed on the toner carrier. A jumping developing method (Japanese Patent Publication No. 58-3) in which an alternating electric field is applied between the carrier and the latent image carrier to perform development.
No. 2375) is preferably used.

This method increases the chance of contact between the sleeve and the toner by applying the magnetic toner on the sleeve in a very thin manner, enables sufficient triboelectric charging, supports the magnetic toner by a magnetic force, By moving the toner relatively, the toner particles are aggregated with each other and sufficiently rubbed with the sleeve, so that an excellent image can be obtained.

Further, since the thin toner layer of the toner carrier is not in contact with the latent image carrier, even when an organic photoconductor which is inexpensive and easily mass-produced is used, its life is long and it can be adapted to high speed. Can be.

As for the fixing step, the most common method at present is a heat compression method using a heat roller. The heat compression bonding method using a heat roller performs fixing by allowing the toner image surface of a sheet to be fixed to pass through the surface of a heat roller having a surface formed of a material having releasability with respect to toner while contacting the surface under pressure. . In this method, since the surface of the heat roller and the toner image of the sheet to be fixed come into contact with each other under pressure, the heat efficiency when fixing the toner image on the sheet to be fixed is extremely good, and the fixing can be performed quickly. It is very effective in high-speed electrophotographic copying machines.

In recent years, such a copying apparatus has been strictly sought for smaller size, lighter weight, higher speed, lower energy, and higher reliability, and as a result, the performance required for the toner has become higher. It is getting more advanced.

For example, in response to the demand for low energy, most of the power consumption is used for the heat source of the fixing device.
The heat compression bonding method using a heat roller is disadvantageous. To overcome this, it is necessary to lower the temperature of the heat roller as much as possible, and it is necessary to improve the melting characteristics of the toner.

[0010] A problem with the conventional low-meltable toner that can be melted is that when toner on a transfer material such as paper comes into contact with the heat roller, the toner adheres to the heat roller surface and stains the image. Becomes narrower. The fluidity of the toner decreases, and in extreme cases, blocking occurs. Contamination of the toner carrier and the electrostatic latent image carrier. ,, Charging characteristics and image deterioration. Efficiency reduction during toner production. Etc. occur.

Specifically, conventionally, for the purpose of preventing the toner from adhering to the surface of the fixing roller, a method of adding a wax such as low molecular weight polyethylene or polypropylene which sufficiently melts when heated in order to increase the releasability of the toner has been proposed. Although this method is effective in preventing offset, it tends to increase the cohesiveness of the toner, destabilize the charging characteristics, and reduce the durability. Therefore, various attempts have been made to improve the binder resin as another method.

For example, a method is known in which the glass transition temperature (Tg) and the molecular weight of the binder resin in the toner are increased to improve the melt viscoelasticity of the toner. However, in such a method, when the offset phenomenon is improved, the fixing property becomes insufficient, and there is a problem that the fixing property at a low temperature required for high-speed development and energy saving, that is, the low-temperature fixing property is inferior. .

In general, in order to improve the low-temperature fixability of a toner, it is necessary to decrease the viscosity of the toner at the time of melting to increase the adhesion area with a fixing base material. Is required to be reduced.

That is, since the low-temperature fixing property and the offset preventing property have contradictory aspects, it is very difficult to develop a toner that simultaneously satisfies these functions.

In order to solve this problem, for example, Japanese Patent Publication No. 51-23354 discloses a toner comprising a vinyl polymer which is appropriately crosslinked by adding a crosslinking agent and a molecular weight modifier. Japanese Patent No. 6805 discloses a toner having a wide molecular weight distribution such that the ratio between the weight average molecular weight and the number average molecular weight of the α, β unsaturated ethylenic monomer as a constitutional unit is 3.5 to 4.0. Further, a blend-type toner or the like in which Tg, molecular weight, gel content, and the like of a vinyl polymer are combined has been proposed.

Certainly, the toner according to these proposals has a lower fixing temperature (the lowest temperature at which fixing can be performed) and an offset temperature (a temperature at which offset starts to occur) as compared with a toner made of a single resin having a narrow molecular weight distribution. Although the temperature range that can be fixed is widened, if sufficient anti-offset performance is given, the fixing temperature cannot be lowered sufficiently. There was the problem of becoming.

In place of these vinyl resins, there is also a toner obtained by crosslinking a polyester resin which is essentially superior to a vinyl resin in terms of low-temperature fixability, and further adding an offset preventing agent. JP-A-57-2085
No. 59 is proposed. This is excellent in both low-temperature fixability and offset prevention, but has a problem in productivity (pulverizability) as a toner.

Further, in Japanese Patent Application Laid-Open No. 56-116043, a vinyl monomer is polymerized in the presence of a reactive polyester resin, and polymerized through a crosslinking reaction, an addition reaction and a grafting reaction in the course of polymerization. Although a toner using a resin that has been made has been proposed and is improved in terms of pulverizability, the functions of the resins cannot be fully utilized in terms of low-temperature fixability and offset prevention.

Further, a toner simply using a resin obtained by blending two types of vinyl resins (gelling degree of 80% or more and gelling degree of less than 10%) having a different gel content from a polyester resin is disclosed in Japanese Patent Publication No. 1-15063. Although this is proposed in the gazette, it has good low-temperature fixability, but it is still insufficient in anti-offset properties and pulverizability. Even if the proportion of the vinyl resin having a gelation degree of 80% or more is increased for the purpose of improving the offset resistance, the anti-offset property is improved, but the low-temperature fixability is significantly reduced. Gelation degree 1
Sufficient pulverizability cannot be satisfied only by containing less than 0% of a vinyl resin.

On the other hand, in order to satisfy the physical properties required for the toner as described above, crosslinking is performed by reacting a polymer having a carboxylic acid with a metal compound in a binder resin (Japanese Patent Laid-Open No. Sho 57-79). No. 178249, 57-17
No. 8250), or a binder having a vinyl resin monomer and a more specific monoester compound as essential constitutional units and a polyvalent metal compound are reacted and cross-linked via a metal (Japanese Patent Application Laid-Open No. 61-1986). No. 110155, 61-1
No. 10156).

Further, JP-A-63-214760, JP-A-63-217362, and JP-A-63-21736.
In JP-A Nos. 3 and 63-217364, a carboxylic acid group having a molecular weight distribution divided into two groups, a low molecular weight and a high molecular weight, is reacted with a polyvalent metal ion to crosslink ( A dispersion of a metal compound is added to a solution obtained by solution polymerization, and the mixture is heated and reacted), but in any method, the reaction between the binder and the metal compound or the addition of the metal compound to the binder is carried out. The dispersion of the metal compound is not sufficient, and the physical properties required for the toner, particularly the fixing property and the offset resistance, have not yet been satisfied. In addition, since it is necessary to mix a large amount of the metal compound with the binder resin, the compounded metal compound shows a catalytic action on the binder resin depending on conditions, and the binder resin is easily gelled, and as a result, the metal compound is mixed. However, it is difficult to determine the manufacturing conditions for obtaining a desired toner, and even if the manufacturing conditions can be determined, there is a problem that reproducibility is hardly obtained.

Further, in the adjustment of the acid amount in these proposals, the charging characteristics (rising), environmental characteristics (leaving characteristics under high humidity), and image characteristics (fog and density characteristics) of the toner are still insufficient.

Further, JP-A-2-168264, JP-A-2-23569, JP-A-5-173363,
In JP-A-5-173366 and JP-A-5-241371, the molecular weight, the mixing ratio, the acid value and the ratio of the low molecular weight component and the high molecular weight component in the binder resin are controlled, and the fixing property, non-offset property, image Toner binder compositions and toners having improved properties, blocking resistance, charging start-up properties and the like have been proposed, but are still low in perfection.

In particular, in the adjustment of the acid value disclosed in the above-mentioned publication, poor dispersibility of a coloring agent such as magnetic iron oxide, a charge controlling agent (charge controlling agent) and other additives occurs, and a developer or carrier such as a carrier or a sleeve is loaded. Image deterioration such as fog and density reduction due to contamination on the body surface occurs.

Further, the fixing at a lower temperature is insufficient.

In Japanese Patent Application Laid-Open No. 62-9256,
A binder composition for a toner in which two kinds of vinyl resins having different molecular weights and resin acid values are blended is disclosed. However, when using such a binder resin,
In order to improve the compatibility and dispersibility of the toner components, kneading conditions must be strengthened, and the resin of the binder is affected by cutting of molecules and the like, and exhibits desired performance such as offset resistance. It will be difficult to do. If kneading is performed to the extent that molecular breakage does not occur, poor dispersion of other additives will occur immediately, promoting contamination of the surface of the developer carrier such as a carrier or a sleeve, and fogging and scattering of developability. Cause serious problems. In particular, when a polymer having a weight average molecular weight of 1,000,000 or more is used, these phenomena become apparent.

Japanese Unexamined Patent Publication (Kokai) No. 3-72505 discloses a vinyl-based toner binder having a molecular weight of 300,000 or more and using a polyfunctional initiator. Although satisfactory, in addition to the above-described problems, the performance of the developer is deteriorated when left at high temperatures. Although the cause of this phenomenon is not clear, according to our investigation, only the molecular cleavage of the binder resin was promoted during the formation of the toner, so that the proportion of the resin component having a sufficient molecular weight in the toner composition was reduced. It is estimated that it became lower and became weaker to thermal shock.

Further, the various properties required for the above-mentioned toners are often reciprocal to each other, and it is more and more desirable in recent years to satisfy both of them with high performance. Research has been conducted on comprehensive responses that include characteristics, but there is still not enough.

In recent years, the demand for higher speed of the apparatus has required the toner to have further low-temperature fixability, toughness of the toner that can withstand high-speed development, and charging stability that can withstand long-term durability. I have.

However, it is difficult to achieve both the low-temperature fixability described above and the toughness of the toner at the same time, and at present, there is no satisfactory structure in the above-mentioned prior art.

In the magnetic toner used for jumping development, a considerable amount of a fine powdered magnetic material is mixed and dispersed, and a part of the magnetic material is exposed on the surface of the toner particles. Affects the fluidity and triboelectricity of the magnetic toner, and as a result, the development characteristics of the magnetic toner,
There is an unstable factor that causes fluctuation or deterioration of various characteristics required for magnetic toner such as durability.

More specifically, in a conventional jumping development method using a magnetic toner containing a magnetic material, if a long-term repeated development process (for example, copying) is continued, the developer containing the magnetic toner is removed. Liquidity worsens,
Normal frictional electrification cannot be obtained, the electrification tends to be non-uniform, and fog development tends to occur in a low-temperature and low-humidity environment, which tends to be a major problem on toner images. Also,
When the adhesiveness between the binder resin and the magnetic material constituting the magnetic toner particles is weak, the magnetic material is removed from the surface of the magnetic toner by a repeated developing process, and tends to have an adverse effect such as a decrease in toner image density. There is.

When the dispersion of the magnetic substance in the magnetic toner particles is not uniform, small magnetic toner particles containing a large amount of the magnetic substance accumulate on the sleeve, causing a reduction in image density and a reduction in sleeve ghost. In some cases, the occurrence of so-called shading unevenness is observed.

Conventionally, proposals have been made regarding magnetic iron oxide contained in magnetic toners, but they still have points to be improved.

For example, JP-A-62-279352 and JP-A-62-278131 propose a magnetic toner containing a magnetic iron oxide containing a silicon element. Although such a magnetic iron oxide intentionally causes a silicon element to be present inside the magnetic iron oxide, there is still a point to be improved in the fluidity of the magnetic toner containing the magnetic iron oxide.

Further, Japanese Patent Publication No. 3-9045 proposes that the shape of magnetic iron oxide is controlled to be spherical by adding a silicate. In the magnetic iron oxide obtained by this method, a large amount of silicon elements are distributed inside the magnetic iron oxide because silicate is used for controlling the particle size, and the amount of the silicon element on the surface of the magnetic iron oxide is small, The fluidity of the magnetic toner tends to be insufficiently improved.

JP-A-61-34070 proposes a method for producing ferric oxide by adding a hydroxosilicate solution during the oxidation reaction to ferric oxide. Although triiron tetroxide according to this method has a Si element near the surface, the Si element exists in a layer near the surface of the triiron tetroxide, and the surface is vulnerable to mechanical shock such as friction. Have a point.

In order to solve the above-mentioned problems, the present inventors have disclosed in Japanese Patent Application Laid-Open No. 5-72801 a method in which a magnetic iron oxide contains a silicon element, and a magnetic silicon oxide contains all silicon elements in the vicinity of the magnetic material surface. A magnetic toner containing magnetic iron oxide in which 44 to 84% of the ratio is present was proposed.

However, in the magnetic toner containing the magnetic iron oxide, although the fluidity of the toner and the adhesion to the binder resin are sufficiently improved, the silicon element is unevenly distributed on the surface of the magnetic iron oxide. There has been a problem that the charging characteristics are deteriorated when the environment characteristics, particularly, when left for a long period of time under high humidity.

Furthermore, Japanese Patent Application Laid-Open No. 4-362954 discloses a magnetic iron oxide containing both a silicon element and an aluminum element, but has the disadvantage that environmental characteristics are insufficient as in the above-mentioned patent. I have.

Furthermore, Japanese Patent Application Laid-Open No. 5-213620 discloses a magnetic iron oxide containing a silicon component and having a silicon component exposed on the surface. It has disadvantages that are inadequate.

Further, the above-mentioned magnetic iron oxide which contains the silicon element and is abundant in the vicinity of the surface of the magnetic material tends to have insufficient dispersibility in the toner binder resin, and each of the toner constituent components has an excellent property. In order to take advantage of the characteristics, it is necessary for the toner design to select a material having good compatibility of each component and good physical mixing, and also, an image forming system that brings out the excellent characteristics of the toner, and an appropriate It is required to find image forming conditions.

[0043]

SUMMARY OF THE INVENTION It is an object of the present invention to significantly improve the disadvantages of the prior art, improve low-temperature fixability and anti-offset properties, and realize a high-quality image. It is an object of the present invention to provide an image forming method which is less affected by the environment of humidity and can maintain stable charging performance without fog even in long-term durability.

It is another object of the present invention to provide an image forming method which achieves both low-temperature fixability of an image and high durability at a high speed of an apparatus recently required.

[0045]

To achieve the above object, the present invention has the following arrangement. That is, the present invention forms a thin layer of magnetic toner that does not contact the latent image carrier on a toner carrier disposed at a certain gap from the electrostatic latent image carrier. And developing the electrostatic latent image on the electrostatic latent image carrier with the magnetic toner while applying an alternating electric field between the toner image and the latent image carrier. The coating amount per unit area of the magnetic toner thin layer is: w / ρ = 0.5 to 1.4 w; toner coating weight per 1 cm ^{2 of} toner carrier surface (mg) ρ; toner true density (g / cm ³⁾ And the moving speed of the toner carrier surface in the developing region is 1.05 to 2.0 times the moving speed of the electrostatic latent image carrier surface, and the magnetic toner is at least Contains polymer component, magnetic material and charge control agent The polymer component of the composition has a molecular weight of 3) in a GPC chromatogram of a THF-soluble portion of the polymer component which is substantially free of a THF-insoluble component. It has a main peak in a region of × 10 ^{3 to} 3 × 10 ⁴ and a molecular weight of 1 × 10 ^{5 to} 3 × 10 ^6.
And c) a ratio of acid value to total acid value (acid value / total acid value) of 0.7 or less, and a low molecular weight polymer (molecular weight of 5 × 10 in GPC chromatogram). (Region less than ⁴ ) having an acid value (A _VL ) of 2
1 to 35 mgKOH / g, and a high molecular weight polymer (GP
In the C chromatogram, the acid value (A _VH ) of the region having a molecular weight of 5 × 10 ⁴ or more is 0.5 to 11 mgKOH / g, and the relationship between the differences is 10 ≦ (A _VL −A _VH ) ≦ 27. The present invention relates to an image forming method characterized by satisfying.

By making the polymer component of the toner composition as described above, the low-temperature fixability and the anti-offset property can be improved, and the toner containing the polymer component having the above-mentioned composition can be further deposited on the toner carrier. Supply amount of w / ρ = 0.5 to
By setting the moving speed of the toner carrier in the developing area to be as high as 1.05 to 2.0 times the moving speed of the surface of the electrostatic latent image carrier, the temperature, A stable and high charge amount toner coat layer can be obtained with little influence of the humidity environment, and a high-quality image with no fog and high image density can be stably obtained even in long-term durability.

Further, even when the configuration of the present invention is applied at a high process speed, the deterioration due to the fusion of the toner to the toner carrier and the electrostatic latent image carrier, and the deterioration of the toner itself are small and very stable. It shows durability.

The reason that the above effects can be obtained is that the polymer component of the toner composition has the above structure,
Despite improved low-temperature fixability and anti-offset properties, it is resistant to mechanical loads in the low-temperature range and has characteristics that make it difficult to fix, so the toner carrier is rotated at a high speed with a small amount of toner supply. Even under such severe use conditions, since the deterioration due to the fusion of the toner to the toner carrier and the electrostatic latent image carrier and the deterioration of the toner itself are small, the supply amount of the toner onto the toner carrier is w / ρ. = 0.5-
1.4, and the moving speed of the toner carrier surface in the developing area can be set to be 1.05 to 2.0 times higher than the moving speed of the electrostatic latent image carrier surface. This is because, depending on the conditions, a sufficient amount of toner having a high charge amount can be supplied to the latent image.

When the relationship w / ρ between the coating amount per unit area of the magnetic toner thin layer formed on the toner carrier and the true toner density is less than 0.5, development over a wide area such as solid black is performed. If there is a portion that requires a large amount of toner, the amount of toner supplied to the latent image is insufficient, and the image density is reduced. Further, it is not preferable because the toner may adhere to the toner carrier. On the other hand, when the ratio exceeds 1.4, it becomes difficult for the toner to be sufficiently triboelectrically charged, and as a result, the distribution of the toner charge amount is widened, and fog is likely to occur.

The true density of the toner was measured by using a dry automatic densitometer "Acupic 1330" manufactured by Shimadzu Corporation.

When the moving speed of the surface of the toner carrier is less than 1.05 with respect to the moving speed of the surface of the electrostatic latent image, the toner coating amount of the present invention is large enough for development over a wide area such as solid black. When there is a portion that requires the amount of toner, the amount of toner supplied to the latent image is insufficient, and the image density is reduced. If the ratio is more than 2.0, the deterioration of the toner and the adhesion of the toner to the toner carrier may occur, which is not preferable.

The toner composition of the present invention contains substantially THF.
Contains no insolubles. Specifically, the content is 5% by weight or less, preferably 3% by weight or less based on the resin composition.

The THF-insoluble content in the present invention indicates the weight ratio of the polymer component (substantially crosslinked polymer) insoluble in the THF solvent in the resin composition in the toner,
It can be used as a parameter indicating the degree of crosslinking of the resin composition containing the crosslinking component. The THF-insoluble matter is defined by a value measured as follows.

That is, 0.5 to 1.0 g of a toner sample was weighed (w ₁ g), and a cylindrical filter paper (for example, No. No.
86R), subjected to a Soxhlet extractor, extracted with 100 to 200 ml of THF as a solvent for 6 hours, and evaporated the soluble components extracted by the solvent.
After vacuum drying at 100 ° C. for several hours, the amount of the THF-soluble resin component is weighed (w ₂ g). The weight of a component other than the resin component such as a magnetic substance or a pigment in the toner is defined as (w ₃ g). T
The HF insoluble content is obtained from the following equation.

THF insoluble matter (%) = ((w ₁ − (w ₃ + w)
₂ )) / (w ₁ −w ₃ ) × 100

When the content of the THF-insoluble component exceeds 5% by weight, not only the fixing property is deteriorated, but also a problem arises in matching with the heat fixing device used in the embodiment of the present invention.

T of the polymer component in the toner composition of the present invention
The chromatogram of GPC measured by the HF soluble component is 3 × 10 ^{3 to} 3 × 10 ⁴ (more preferably, 5 × 1
0 ^{3 to} 2 × 10 ⁴ ), and has a main peak, and
Molecular weight 1 × 10 ^{5 to} 3 × 10 ⁶ (more preferably, 5 × 1
(0 ⁵ to 1 × 10 ⁶ ).

In the GPC chromatogram, the area ratio of the polymer component having a molecular weight of 1,000,000 or more is 3 to 10%.
It is preferable to show 10%. The presence of 3 to 10% of a THF-soluble component having a molecular weight of 1,000,000 or more improves the offset resistance without inhibiting low-temperature fixing and at the same time improves the storage stability of the developer under high-temperature storage. Can also be increased.

In the present invention, the molecular weight distribution of the polymer component of the toner composition is measured by GPC (gel permeation chromatography) under the following conditions.

<GPC Measurement Conditions for Toner Composition and Resin> Apparatus: GPC-150C (manufactured by Waters) Column: KF801 to 7 (manufactured by Shodex) Temperature: 40 ° C. Solvent: THF (tetrahydrofuran) Flow rate: 1.0 ml / min. Sample: 0.1 ml of a sample having a concentration of 0.05 to 0.6% by weight
Injection The polymer component according to the present invention comprises a low molecular weight polymer (G
The relationship between the acid value (A _VL ) of the PC chromatogram having a molecular weight of less than 5 × 10 ⁴ ) and the acid value (A _VH ) of the high molecular weight polymer (the region having a molecular weight of 5 × 10 ⁴ or more in the GPC chromatogram) is as _follows. , A _VL > A _VH , and more preferably a low molecular weight polymer (molecular weight 5 × 1 in GPC chromatogram).
0 less than ⁴ area) acid value of (A _VL) is 21~35mgKO
H / g and the acid value (A) of a high molecular weight polymer (region having a molecular weight of 5 × 10 ⁴ or more in a GPC chromatogram).
_VH ) is 0.5 to 11 mgKOH / g, and the relation of the difference is 10 ≦ (A _VL −A _VH ) ≦ 27.

As a result of intensive studies, the present inventors have found that, in a toner resin composition comprising a low molecular weight polymer and a high molecular weight polymer, each polymer component having the acid value shown above has low-temperature fixability, It has been found that it is most effective for improving the offset resistance and further the developing property.

The low-temperature fixability is governed by the Tg and molecular weight distribution of the low-molecular-weight component. The low-molecular-weight component contains an acid component.
It has been found that by increasing H / g or more, the viscosity can be made lower than that of the resin composition having the same Tg and the same molecular weight distribution as the acid value outside the above range.

This is because the acid value of the high molecular weight component is set to be lower than the acid value of the low molecular weight component by 10 mg KOH / g or more (acid value 0.5 to 11 mg KOH / g), whereby the molecular weight of the low molecular weight component and the high molecular weight component is reduced. It is considered that the entanglement of the chains is suppressed to some extent, so that the viscosity can be reduced on the low temperature side and the elasticity can be maintained on the high temperature side. This leads to low-temperature fixing in a high-speed machine and improvement in developing characteristics.

On the other hand, if the difference in the acid value exceeds 27, the mixing property between the low molecular weight component and the high molecular weight component becomes defective, and the durability offset property and the developability deteriorate.

Further, the acid value of the low molecular weight component is 21 mgK
At OH / g or more, it was found that the rising property of the charge was good.

On the other hand, the acid value of the low molecular weight component is 35 mg KO
If it exceeds H / g, environmental characteristics, particularly, developability under high humidity are impaired.

When the acid value of the high molecular weight component is less than 0.5, the low molecular weight component (acid value 21 to 35 mgKOH /
The miscibility with g) is inferior, and the developability, particularly the fogging property, deteriorates.

The polymer component has an acid value / total acid value ratio of 0.7 or less (more preferably 0.4 to 0.6).
Is more preferable. The value of acid value / total acid value is 0.
If it exceeds 7, the balance of charging of the toner, that is, the balance of charging and discharging, tends to be charged, and the toner charging stability tends to be reduced.

The polymer component is the polymer component THF.
In the GPC chromatogram of the soluble portion, the molecular weight was 3 × 10
It is preferable to have a minimum value (Min) in a region of ⁴ or more and less than 1 × 10 ⁵ . In order to achieve both low-temperature fixability and high-temperature offset resistance, it is preferable that the low-molecular-weight polymer component and the high-molecular-weight polymer component have independent molecular weight distributions.

[0070] Further, the polymer component of the toner resin composition of the present invention, in relation to the low molecular weight polymer component and a high molecular weight polymer component with respect to the mixing _{ratio, W L: W H = 50} : 50~90 : 10 is preferably satisfied. The reason is that when the ratio of the low molecular weight polymer component to the high molecular weight polymer component is within this range, the fixing property and the offset resistance are improved. That is, if the low molecular weight component is less than 50% by weight, the fixability decreases, while if the high molecular weight component is less than 10% by weight, the high temperature offset resistance decreases.

Further, with respect to the relationship between the mixing amount and the acid value,

[0072]

[Outside 4] Is preferably satisfied. The reason is that the mixing amount of the low molecular weight component and the high molecular weight component and their respective acid values do not satisfy the relationship of the above formula, that is,

[0073]

[Outside 5] When the acid value of the low molecular weight component in the entire resin is lower than four times the acid value of the high molecular weight resin, the mixing property between the low molecular weight polymer component and the high molecular weight polymer component increases, Low viscosity and high elasticity on the high temperature side tend to be more difficult to emphasize.

Also,

[0075]

[Outside 6] Is less than 11, the rising characteristics of the charge are reduced, while if it exceeds 30, the developability under high humidity tends to be reduced.

In the present invention, the acid value (JIS acid value) of the low molecular weight polymer component, the polymer component and the high molecular weight polymer component is determined by the following method.

<Preparation of each component> [Apparatus configuration] LC-908 (manufactured by Nippon Kagaku Kogyo Co., Ltd.) JRS-86 (company; repeat injector) JAR-2 (company; autosampler) FC-201 (Gilson; Hula cushion collector)

[Column configuration] JAIGEL-1H to 5H (20φ × 600 mm: preparative column)

[Measurement conditions] Temperature: 40 ° C. Solvent: THF Flow rate: 5 ml / min. Detector: RI

In the sample, additives other than the polymer component are separated in advance. As a preparative method, the molecular weight is 5 × 10 ₄
The elution time is measured in advance, and before and after the elution time, the low molecular weight polymer component and the high molecular weight polymer component are separated. The solvent is removed from the sampled sample to obtain a sample for acid value measurement.

<Measurement of Acid Value (JIS Acid Value)> 1) A crushed sample of 0.1 to 0.2 g is precisely weighed, and its weight is defined as W (g).

2) Put the sample in a 20 cc Erlenmeyer flask,
10 cc of a mixed solution of toluene / ethanol (2: 1) is added and dissolved.

3) Add a few drops of an alcohol solution of phenolphthalein as an indicator.

4) The solution in the flask is titrated with a 0.1N KOH alcohol solution using a burette.

At this time, the used amount of the KOH solution was S (ml).
And At the same time, a blank test is performed, and the amount of the KOH solution at this time is defined as B (ml).

5) Calculate the acid value by the following equation.

[0087]

[Outside 7]

The measurement of the total acid value in the present invention is carried out as follows. <Measurement of total acid value> 1) The sample is used after removing additives other than the polymer component in advance. Approximately 2 g of a crushed sample is precisely weighed, and the weight is
(G).

2) A sample was placed in a 200 cc Erlenmeyer flask, and 30 cc of 1,4-dioxane, 10 cc of pyridine,
20 mg of 4-dimethylaminopyridine is added and dissolved for 1 hour.

3) 3.5 cc of ion-exchanged water is added and refluxed for 4 hours. Then cool.

4) Add a few drops of a phenolphthalein alcohol solution as an indicator.

5) The solution in the flask is titrated with a 0.1N KOH THF solution using a burette.
The amount of the KOH solution at this time is defined as S ′ (ml). At the same time, a blank test was performed, and the amount of the KOH solution at this time was changed to B '(m
l).

6) The total acid value is measured by the following equation.

[0094]

[Outside 8]

As the KOH THF solution, KOH6.
6 g of ion-exchanged water (20 cc) was added and dissolved.
20 cc and 100 cc of ion-exchanged water are added, and then methanol is added while stirring until the mixture becomes transparent.

Examples of the monomer for adjusting the acid value of the polymer component include acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid and the like,
Alternatively, there are β-alkyl derivatives, unsaturated dicarboxylic acids such as fumaric acid, maleic acid, and citraconic acid and monoester derivatives thereof, and maleic anhydride. These monomers are used alone or in combination with other monomers. By polymerizing, a desired polymer can be produced.
Among them, it is particularly preferable to use a monoester derivative of an unsaturated dicarboxylic acid for controlling the acid value / total acid value.

More specifically, for example, monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monoallyl maleate,
Monoesters of α, β-unsaturated dicarboxylic acids such as monophenyl maleate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monophenyl fumarate, etc .; monobutyl n-butenylsuccinate, monomethyl n-octenylsuccinate, Monoesters of alkenyl dicarboxylic acids such as monoethyl n-butenylmalonate, monomethyl n-dodecenylglutarate and monobutyl n-butenyladipate; monomethyl phthalate, monoethyl phthalate, monobutyl phthalate and the like And monoesters of aromatic dicarboxylic acids.

The carboxyl group-containing monomer as described above may be added in an amount of 1 to 20% by weight, preferably 3 to 15% by weight, based on all monomers constituting the polymer side of the binder resin.

The reason that the monoester monomer of dicarboxylic acid is selected as described above is that it is not appropriate to use an acid monomer having high solubility in an aqueous suspension in the suspension polymerization. This is because it is preferable to use the compound in the form of an ester having low solubility.

In the present invention, the carboxylic acid groups and carboxylic acid ester sites in the copolymer obtained by the above method can be saponified by alkali treatment. That is, it is preferable that the carboxylic acid group or the carboxylic acid ester moiety is changed to a polar functional group by reacting with a cation component of an alkali. This is because, even if the polymer side component of the binder resin contains a carboxyl group that reacts with the metal-containing compound, if the carboxyl group is dehydrated, that is, the ring is closed, the efficiency of the crosslinking reaction decreases.

This alkali treatment may be carried out after the production of the binder resin, while immersing as an aqueous solution in the solvent used during the polymerization and stirring. Examples of the alkali that can be used in the present invention include hydroxides of alkali metals and alkaline earth metals such as Na, K, Ca, Li, Mg, and Ba;
hydroxides of transition metals such as n, Ag, Pb, and Ni; and hydroxides of quaternary ammonium salts such as ammonium salts, alkylammonium salts, and pyridinium salts. Particularly preferred examples include NaOH and KOH. .

In the present invention, the saponification reaction does not need to be carried out over all of the carboxylic acid groups and carboxylic acid ester sites in the copolymer. I just need to change.

The amount of the alkali used in the saponification reaction is difficult to determine unconditionally depending on the type of the polar group in the binder resin, the dispersion method, the type of the constituent monomers, and the like. What is necessary is just the equivalent of 02 to 5 times. When the amount is less than 0.02 equivalent, the saponification reaction is not sufficient, and the number of polar functional groups generated by the reaction is reduced, and as a result, the subsequent crosslinking reaction becomes insufficient. On the other hand, when the amount exceeds 5 times equivalent, the functional group such as a carboxylic acid ester site is adversely affected by hydrolysis of the ester, generation of a salt by a saponification reaction, and the like.

When the alkali treatment is performed at an equivalent of 0.02 to 5 times the acid value, the residual cation concentration after the treatment is 5 to 1%.
It is contained between 000 ppm and can be preferably used to regulate the amount of alkali.

The toner composition according to the present invention has a glass transition temperature (Tg) of 50 to 70 ° C., preferably 55 to 65 ° C. from the viewpoint of storage stability. This may cause deterioration of the developer and offset at the time of fixing. On the other hand, when Tg exceeds 70 ° C., it adversely affects the entire fixing property.

[0106] relationship Tg _H of Tg _L and a high molecular weight polymer having a low molecular weight polymer of the resin composition of the present invention is preferably in the range of _{Tg L ≧ Tg H -5 (℃} ), Tg L If there is less than Tg _H -5, there is a tendency that developing property is deteriorated. More preferably T
g _L ≧ Tg _H is good.

As a method for producing the binder resin according to the present invention, a high molecular weight polymer and a low molecular weight polymer are separately synthesized by a solution polymerization method, then they are mixed in a solution state, and then the solvent is desolvated. Alternatively, a low-molecular-weight polymer obtained by melt-kneading with an extractor or the like is further dissolved in a monomer constituting a high-molecular-weight polymer obtained by dissolving a low-molecular-weight polymer, and suspension polymerization is performed. A two-stage polymerization method for drying and obtaining a binder resin is exemplified. However, the dry blending method has problems in uniform dispersion and compatibility, and the two-stage polymerization method has many advantages in uniform dispersibility and the like, but increases the amount of low molecular weight to higher than high molecular weight. In the presence of low molecular weight components, not only is it difficult to synthesize the desired high molecular weight components desired in the present invention, but also there are drawbacks such as unnecessary low molecular weight components being by-produced. The solution blending method is most suitable for application to the present invention. As a method for introducing a predetermined acid value into the low molecular weight component, solution polymerization is preferred. The acid value can be easily set as compared with the hydrogen polymerization method.

As a polymerization method which can be used in the present invention as a method for synthesizing the high molecular weight component of the resin composition according to the present invention, there are a solution polymerization method, an emulsion polymerization method and a suspension polymerization method.

Among them, the emulsion polymerization method is a method in which a monomer (monomer) almost insoluble in water is dispersed in an aqueous phase as small particles with an emulsifier, and polymerization is carried out using a water-soluble polymerization initiator. . In this method, the reaction heat can be easily adjusted, and the phase in which the polymerization is performed (oil phase composed of a polymer and a monomer)
And the aqueous phase are separate, so that the termination reaction rate is low, resulting in a high polymerization rate and a high degree of polymerization. Further, due to the relatively simple polymerization process and the fact that the polymerization product is fine particles, in the production of toner,
There is an advantage as a method for producing a binder resin for a toner because it is easy to mix with a colorant, a charge control agent and other additives.

However, the resulting polymer tends to be impure due to the added emulsifier, and an operation such as salting out is required to take out the polymer. To avoid this inconvenience, suspension polymerization is convenient.

In the suspension polymerization, 100 parts by weight or less of the monomer (preferably 1 part by weight) is added to 100 parts by weight of the aqueous solvent.
(0 to 90 parts by weight). Examples of usable dispersants include polyvinyl alcohol, partially saponified polyvinyl alcohol, calcium phosphate, and the like. There is an appropriate amount in terms of the amount of a monomer relative to an aqueous solvent, and generally 0.05 to 1 based on 100 parts by weight of an aqueous solvent. Used in parts by weight. The polymerization temperature is suitably from 50 to 95 ° C, but should be appropriately selected depending on the initiator used and the intended polymer.

As the high molecular weight component of the resin composition used in the present invention, a polyfunctional polymerization initiator alone or a monofunctional polymerization initiator as exemplified below is used in order to achieve the object of the present invention.

Specific examples of the polyfunctional polymerization initiator having a polyfunctional structure include 1,1-di-t-butylperoxy-
3,3,5-trimethylcyclohexane, 1,3-bis- (t-butylperoxyisopropyl) benzene,
2,5-dimethyl-2,5- (t-butylperoxy)
Hexane, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexyne-3, tris- (t-butylperoxy) triazine, 1,1-di-t-butylperoxycyclohexane, , 2-Di-tert-butylperoxybutane, 4,4-di-tert-butylperoxyvaleric acid n-butyl ester, di-tert-butylperoxyhexahydroterephthalate, di-tert-butylperoxy Azelate, di-t-butylperoxytrimethyl adipate, 2,2-bis- (4,4-dito-
Butylperoxycyclohexyl) propane, 2,2-
A polyfunctional polymerization initiator having a functional group having a polymerization initiation function such as two or more peroxide groups in one molecule such as t-butylperoxyoctane and various polymer oxides, and diallyl peroxydicarbonate; In one molecule such as butylperoxymaleic acid, t-butylperoxyallyl carbonate and t-butylperoxyisopropyl fumarate, both a functional group having a polymerization initiation function such as a peroxide group and a polymerizable unsaturated group are contained. Selected from polyfunctional polymerization initiators having

Of these, preferred are 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-tert-butylperoxycyclohexane, di-tert-butyl. Peroxyhexahydroterephthalate, di-t-butylperoxyazelate and 2,2-bis- (4,4-di-t-butylperoxycyclohexyl) propane, and t-butylperoxyallyl carbonate.

These polyfunctional polymerization initiators are preferably used in combination with a monofunctional polymerization initiator in order to satisfy various performances required as a binder for a toner.
Particularly, it is preferable to use the polyfunctional polymerization initiator together with a polymerization initiator having a decomposition temperature lower than the decomposition temperature for obtaining a half-life of 10 hours.

Specifically, benzoyl peroxide,
1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-di (t
-Butylperoxy) valerate, dicumyl peroxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, t-butylperoxycumene, di-t
Organic peroxides such as -butyl peroxide and azo and diazo compounds such as azobisisobutyronitrile and diazoaminoazobenzene can be used.

These monofunctional polymerization initiators may be added to the monomer at the same time as the polyfunctional polymerization initiator, but in order to keep the initiator efficiency of the polyfunctional polymerization initiator at an appropriate level. It is preferable to add the compound after the half-life of the polyfunctional polymerization initiator has elapsed under any polymerization conditions.

These initiators are used in 0.05 to 2 parts by weight per 100 parts by weight of the monomer.

The high molecular weight component of the resin composition used in the present invention contains a crosslinkable monomer as exemplified below to achieve the object of the present invention.

As the crosslinkable monomer, a monomer having two or more polymerizable double bonds is mainly used, and specific examples thereof include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; Diacrylate compounds; for example, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate,
1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and acrylates of the above compounds replaced with methacrylates; diacrylate compounds linked by an alkyl chain containing an ether bond , Such as diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and acrylates of the above compounds instead of methacrylate Diacrylate compounds linked by a chain containing an aromatic group and an ether bond, for example, polyoxyethylene (2) -2,2-bis ( - hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,
2-bis (4-hydroxyphenyl) propane diacrylate and those obtained by replacing the acrylates of the above compounds with methacrylates; further, polyester-type diacrylate compounds, for example, trade name MANDA (Nippon Kayaku) . As multifunctional crosslinking agents, pentaerythritol acrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate, and acrylates of the above compounds to methacrylate Alternatives; triallyl cyanurate, triallyl trimellitate; and the like.

These crosslinking agents can be used in combination with other monomer components 10
1% by weight or less, preferably 0.00% with respect to 0% by weight
It is preferable to use it in the range of 1 to 0.05% by weight.

Of these crosslinkable monomers, those which are preferably used for the developer resin from the viewpoint of fixing properties and anti-offset properties include aromatic divinyl compounds (particularly divinylbenzene), aromatic groups and ether bonds. And diacrylate compounds linked by a chain containing the same.

By mixing the high-molecular-weight polymer constituting the resin composition according to the present invention with a low-molecular-weight wax in advance, phase separation in the micro-region is alleviated, and the low-molecular-weight component does not re-aggregate. A good dispersion state with the molecular polymer is obtained.

Examples of the low molecular weight wax applicable to the present invention include polypropylene, polyethylene, microcrystalline wax, carnauba wax, sasol wax, paraffin wax, higher alcohol wax,
Examples include waxy substances such as ester waxes, and oxides and graft-modified products thereof.

The weight average molecular weight of these low molecular weight waxes is preferably 30,000 or less, preferably 10,000 or less.
The addition amount is preferably about 1 to 20 parts by weight based on 100 parts by weight of the binder polymer component.

It is preferable that these low molecular weight waxes are added to and mixed with the binder resin in advance when producing the toner. In particular, a method in which the low molecular weight wax and the high molecular weight polymer are preliminarily dissolved in a solvent during the production of the binder, and then mixed with the low molecular weight polymer solution is preferable.

The solid concentration of the polymer solution is determined by the dispersion efficiency,
In consideration of prevention of deterioration of the resin at the time of stirring, operability, etc., 5 to 70
It is preferable that the content of the preliminary solution of the high molecular weight polymer component and the polyolefin polymer be 5 to 60% by weight or less, and that of the low molecular weight polymer solution be 5 to 70% by weight or less.

The method for dissolving or dispersing the high molecular weight polymer component and the polyolefin polymer is carried out by stirring and mixing.
A batch type or a continuous type may be used.

The method of mixing the low-molecular-weight polymer solution is to add 10 to 1000 parts by weight of the low-molecular-weight polymer solution to the solid content of the preliminary solution and to carry out stirring and mixing. But it can be a continuous type.

The organic solvent used for mixing the solution of the resin composition according to the present invention includes, for example, benzene, toluene,
Xylol, solvent naphtha 1, solvent naphtha 2, solvent naphtha 3, cyclohexane, ethylbenzene, hydrocarbon solvents such as Solvesso 100, Solvesso 150, mineral spirits, methanol, ethanol, iso-propyl alcohol, n-butyl alcohol, alcohol solvents such as sec-butyl alcohol, iso-butyl alcohol, amyl alcohol, and cyclohexanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and ester solvents such as ethyl acetate, n-butyl acetate, and cellosolve acetate. Solvents include ether solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, and methyl carbitol. Aromatic in these,
Ketone and ester solvents are preferred. They may be used in combination.

The method for removing the organic solvent is to heat the organic solvent solution of the polymer, remove 10 to 80% by weight of the organic solvent under normal pressure, and remove the remaining solvent under reduced pressure. At this time, the organic solvent solution has a boiling point of at least the boiling point of the used organic solvent,
It is necessary to keep the temperature below 0 ° C. Below the boiling point of the organic solvent, not only is the efficiency at the time of solvent distillation low, but also unnecessary shearing force is applied to the polymer in the organic solvent, and the redispersion of each constituent polymer is promoted, and in a micro state, Causes phase separation.
If the temperature exceeds 200 ° C., the depolymerization of the polymer proceeds, and not only oligomer formation due to molecular cleavage, but also incorporation of residual monomers into the product resin due to monomer generation, which is unsuitable as an electrophotographic toner binder Becomes

On the other hand, as a method for synthesizing the low molecular weight component of the binder resin according to the present invention, a known method can be used. However, in the bulk polymerization method, a polymer having a low molecular weight can be obtained by increasing the termination reaction rate by polymerizing at a high temperature, but there is a problem that the reaction is difficult to control.
In that regard, in the solution polymerization method, a low molecular weight polymer can be easily obtained under mild conditions by utilizing the difference in radical chain transfer depending on the solvent, and by adjusting the amount of the initiator and the reaction temperature, It is preferable to obtain a low molecular weight compound in the resin composition used in the present invention. In particular, minimize the amount of initiator used,
In order to minimize the influence of the initiator residue, a solution polymerization method under a pressurized condition is also effective.

Examples of the comonomer for obtaining the polymer side component of the binder resin used on the developing side of the present invention and the monomer for obtaining the low molecular side component include the following.

For example, styrene, o-methylstyrene, m
-Methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene,
2,4-dimethylstyrene, pn-butylstyrene,
Styrene such as p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene and derivatives thereof; ethylene Ethylenically unsaturated monoolefins such as propylene, butylene and isobutylene; unsaturated polyenes such as butadiene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl acetate, vinyl propionate, Vinyl esters such as vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid Stearyl, methacrylic Α-methylene aliphatic monocarboxylic esters such as phenyl, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, and n-acrylate Acrylates such as octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate and phenyl acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl Vinyl ketones such as methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyls such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone Vinyl compounds such as vinyl compounds, vinyl naphthalenes, and acrylic or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide;

Among these, a combination of monomers that results in a styrene-based copolymer and a styrene-acrylic copolymer is preferred.

It is preferable that both the low molecular weight component and the high molecular weight component contain at least 65 parts by weight of the styrene polymer component. By containing 65 parts by weight or more of each of the styrene components, the mixing property is improved.

The present inventors have disclosed in Japanese Patent Application Laid-Open No. 5-72801 a magnetic oxide containing a silicon element in magnetic iron oxide and having a total silicon content of 44 to 84% near the surface of the magnetic material. A magnetic toner containing iron was proposed.

However, as described above, in this system, there was a problem that the charging characteristics were deteriorated in the environmental characteristics, particularly, when left for a long time under high humidity.

Further, as the speed of an image forming apparatus such as a printer is increased and the number of durable sheets is increased, there is a demand for a toner having a high durability and a very high material dispersibility.

By controlling the outermost surface, composition and structure of the magnetic iron oxide, the present inventors have found that a magnetic toner containing the magnetic iron oxide has excellent fluidity, long-term storage stability, durability, and toner stability. It has been found that the dispersibility of the magnetic substance in the medium can be extremely excellent.

That is, in the present invention, the content of the silicon element in the magnetic iron oxide used in the magnetic toner is 0.1 to 5.0% by weight, preferably 0.4 to 2.0% by weight based on the iron element.
% By weight (more preferably 0.5 to 0.9% by weight).

When the content of the silicon element is less than 0.4% by weight or the Fe / Si atomic ratio exceeds 4.0,
The effect of improving the magnetic toner, particularly the improvement of the fluidity of the magnetic toner, is weak. When the content of the silicon element is more than 2.0% by weight or the Fe / Si atomic ratio is less than 1.2, deterioration of environmental characteristics, particularly, chargeability occurs for a long period of time under high humidity. Further, the durability of the toner and the dispersibility of the magnetic iron oxide in the toner binder resin deteriorate.

A preferred system of the magnetic iron oxide particles of the present invention is that the surface of the magnetic iron oxide particles is 0.01% in terms of SiO _2.
To 1.00% by weight (more preferably, 0.05 to 0.3%
% By weight) of silicon oxide. If the silicon oxide on the surface of the magnetic iron oxide particles is less than 0.01% by weight in terms of SiO ₂ , further improvement in the fluidity of the magnetic toner cannot be expected. On the other hand, when the content exceeds 1.00% by weight, the charge amount decreases due to environmental characteristics, particularly, long-term storage and long-term durability under high humidity.

Further, a preferable system of the magnetic iron oxide particles has a smoothness of 0.3 to 0.8, preferably 0.45
To 0.7, more preferably 0.5 to 0.7. The smoothness in the present invention is related to the amount of pores on the surface of the magnetic iron oxide. When the smoothness is less than 0.3, there are many pores on the surface of the magnetic iron oxide, and the adsorption of water is promoted. Is done.

Further, one of the more preferable systems of the magnetic iron oxide particles is that the bulk density thereof satisfies 0.8 g / cm ³ or more, preferably 1.0 g / cm ³ or more.
When the bulk density is less than 0.8 g / cm ³ , it has an adverse effect on physical mixing with other toner materials during toner production, and the magnetic substance dispersibility in the toner is deteriorated.

Further, as one of the more preferable systems of the magnetic iron oxide particles, the specific surface area is 15.0 m ² / g or less.
Preferably, it satisfies 12.0 m ² / g or less. When the specific surface area exceeds 15.0 m ² / g, the water absorption of the magnetic iron oxide particles increases, which adversely affects the hygroscopicity and chargeability of the toner containing the magnetic iron oxide particles.

As a result of intensive studies, the present inventors have found that the water absorption characteristics of magnetic iron oxide are largely related to the pores on its surface, and it is most important to control the pore distribution. Was. In terms of pore distribution, the total pore volume of the magnetic iron oxide particles is from 7.0 × 10 ^{−3 to} 15.0 × 10 ^3.
-3 ml / g, more preferably 8.0 × 10 ^{-3 to} 12.
It is preferably 0 × 10 ⁻³ ml / g.

When the total pore volume is less than 7.0 × 10 ⁻³ ml / g, the adhesion to the toner binder resin is weak, and the magnetic iron oxide particles are detached from the toner. It is easy to give adverse effects such as lowering. Furthermore, the surface pores of the magnetic iron oxide particles greatly contribute to the adsorption of water, and greatly affect the water adsorption characteristics of the toner containing the magnetic iron oxide particles. Further, the surface moisture content of the toner greatly affects the charging characteristics of the toner.

The total pore volume on the surface of the magnetic iron oxide particles is 7.0.
When the concentration is less than × 10 ⁻³ ml / g, the water retention ability of the magnetic iron oxide particles is remarkably reduced. Particularly in a low humidity environment, the toner containing the magnetic iron oxide particles is easily charged up and the image density is lowered. Tends to occur.

When the total pore volume exceeds 15.0 × 10 ⁻³ ml / g, the water adsorbability of the magnetic iron oxide particles increases, and the magnetic iron oxide particles are contained particularly in a high humidity environment. The toner easily absorbs moisture when left to stand, causing a decrease in the charge amount, and as a result, a decrease in image density.

Further, in the magnetic iron oxide particles used in the present invention, the total specific surface area of the pores (micropores) having a pore diameter of less than 20 mm in the pore distribution on the surface is more than 20 mm (2 mm).
It is preferable that the total specific surface area of the pores (mesopores) of 0 ° to 500 °) is not more than the total specific surface area.

The surface pore diameter of the magnetic iron oxide particles has a large effect on water adsorption, and smaller pores make it difficult for adsorbed water to desorb. When the total specific surface area of the pores having a pore diameter of less than 20 mm of the magnetic iron oxide particles exceeds the total specific surface area of the pores having a pore diameter of 20 mm or more, more adsorption sites where adsorption water is difficult to desorb are present. In the toner containing the magnetic iron oxide, the charging characteristics are remarkably reduced particularly when the toner is left under high humidity for a long period of time, and the charging characteristics are likely to be unable to recover.

Furthermore, it is preferable that the magnetic iron oxide particles used in the present invention basically do not cause hysteresis between the adsorption and desorption isotherms in the adsorption and desorption isotherms by nitrogen. That is, it is preferable that the difference in the amount of gas adsorbed and desorbed at an arbitrary relative pressure on the isotherm is 4% or less.

The adsorption / desorption isotherm due to nitrogen has a hysteresis,
That is, the difference is caused by having an ink bottle type pore in which the pore entrance is narrow in the pore and the internal pore is wide, and the adsorbed substance (water)
This makes the structure difficult to be desorbed, and adversely affects the charging characteristics of the toner containing the magnetic iron oxide, particularly under high humidity.

The magnetic iron oxide particles used in the present invention have a water content of 0.4% at a temperature of 23.5 ° C. and a humidity of 65%.
To 1.0% by weight (more preferably, 0.45 to 0.90%
Wt.), And the water content at a temperature of 32.5 ° C./85% is 0.6 to 1.5 wt.% (More preferably, 0.1 wt.%).
60 to 1.10% by weight), and the difference in water content in each environment is preferably 0.6% by weight or less (more preferably, 0.3% by weight or less).

When the value is below the above range, the toner is liable to be charged up particularly under low humidity, and when it exceeds the value, the charge amount is reduced. Further, when the difference in the water content in each environment exceeds 0.6% by weight, a difference in image characteristics due to the environment difference occurs, which is not so preferable.

Furthermore, the magnetic iron oxide particles used in the present invention may be treated with aluminum hydroxide.

The magnetic iron oxide particles used in the present invention have an average particle size of 0.1 to 0.4 μm, preferably 0.1 to 0.4 μm.
It preferably has a thickness of about 0.3 μm.

By combining the above-mentioned magnetic iron oxide particles containing a silicon element with the polymer component having an adjusted acid value of the present invention, developing characteristics such as charging characteristics, durability, image characteristics (reproducibility, fog) and the like are obtained. Has been confirmed to improve dramatically. This is presumably because "wetting" at the interface between the polymer and the magnetic iron oxide particles was appropriately improved and the dispersibility in the toner was improved.

The method for measuring the various physical property data of the magnetic iron oxide particles in the present invention will be described in detail below.

[0161] (1) SiO ₂ amount of magnetic oxide Tetsukaku particle surfaces at the surface SiO ₂ amount present invention of the magnetic iron oxide particles,
Ask for:

That is, 1N NaO was added to 15 g of the sample.
300 ml of H aqueous solution is added and ultrasonically dispersed (10 minutes). Then, the mixture is heated to 50 ° C. and stirred for 30 minutes. afterwards,
Separate the supernatant with a centrifuge (10,000 rpm, 10 minutes).

A 1N-NaOH aqueous solution is added again, and the mixture is ultrasonically dispersed (5 minutes), followed by centrifugal separation. The supernatant is cut off and the solid content is dried. The amount of surface SiO ₂ is calculated by measuring and quantifying the sample before and after the alkali washing with a fluorescent X-ray analyzer.

(2) Bulk Density The bulk density of the magnetic iron oxide particles in the present invention is determined according to JIS-K
It measured according to the pigment test method of -5101.

(3) Smoothness In the present invention, the smoothness D of the magnetic iron oxide particles is determined as follows.

[0166]

[Outside 9]

(4) BET Specific Surface Area The BET of the magnetic iron oxide particles is measured as follows.

The BET specific surface area was measured by Yuasa Ionics Co., Ltd., fully automatic gas adsorption amount measuring apparatus: Auto Soap 1
And BET multipoint method using nitrogen as the adsorption gas.

The sample was pretreated at 50 ° C.
For 10 hours.

(5) Average particle size and surface area of magnetic iron oxide particles Measurement of the average particle size and calculation of the surface area of magnetic iron oxide are performed as follows.

A transmission electron micrograph of the magnetic powder was taken,
After arbitrarily selecting 250 pieces per 40,000 times,
The Martin diameter (the length of a line segment bisecting the projected area in a fixed direction) in the projected diameter is measured, and this is represented by the number average diameter.

For the calculation of the surface area, the magnetic iron oxide is assumed to be spherical with the average particle diameter being the diameter, and the density of the magnetic iron oxide is measured by a usual method to determine the value of the surface area.

(6) Pore Distribution The total pore volume, total specific surface area of pores having a pore diameter of less than 20 °, and total pore volume of pores having a pore diameter of 20 ° or more in the present invention are shown in FIG. The specific surface area is determined as follows.

That is, as a measuring device, a fully automatic gas adsorption device: Auto Soap 1 (Yuasa Ionics Co., Ltd.)
Using nitrogen as the adsorption gas and a relative pressure of 0
Measurement of 40 points of adsorption and desorption of 40 points to 1.0 was performed, and de Boer's t-plot method, kelvin
Formula and B. J. The pore distribution was calculated by the H method, and each was obtained. The pretreatment of the sample was performed at 50 ° C for 10 minutes.
Degas for hours.

(7) Water Content In the present invention, the water content of the magnetic iron oxide particles is determined as follows. That is, the amount of water is 23.5 ° C. and 65% humidity.
The magnetic iron oxide particles were allowed to stand in an environment of 32.5 ° C. and a humidity of 85% for 3 days, and thereafter, a micro moisture analyzer AQ-6 and an automatic moisture vaporizer SE-24 manufactured by Hiranuma Sangyo Co., Ltd. were used. The sample was heated to 130 ° C. while passing a nitrogen gas carrier at 0.2 L / min, and the measurement was performed.

(8) Silicon Element Amount The silicon element amount in the magnetic iron oxide particles of the present invention can be determined by using a fluorescent X-ray analyzer SYSTEM3080 (Rigaku Corporation).
And X-ray fluorescence analysis according to JIS K0119 "General rules for X-ray fluorescence analysis".

The magnetic iron oxide particles used in the magnetic toner of the present invention are preferably used in an amount of 20 parts by weight to 200 parts by weight based on 100 parts by weight of the binder resin. It is more preferable to use 30 to 150 parts by weight.

In some cases, the magnetic iron oxide particles used in the magnetic toner of the present invention may be treated with a silane coupling agent, a titanium coupling agent, titanate, aminosilane, an organosilicon compound, or the like.

Examples of the silane coupling agent used for the surface treatment of the magnetic iron oxide particles of the present invention include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, and the like. Allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, Triorganosilyl acrylate,
Examples thereof include vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, and 1,3-diphenyltetramethyldisiloxane.

Examples of the titanium coupling agent include isopropoxytitanium triisostearate, isopropoxytitanium dimethacrylate isostearate,
Isopropoxy titanium tridodecyl benzene sulfonate, isopropoxy titanium tris dioctyl phosphate, isopropoxy titanium tri N-ethylaminoethyl aminato, titanium bis dioctyl pyrophosphate oxy acetate, bis dioctyl phosphate ethylene dioctyl phosphite, di-n-butoxy Bistriethanol aminato titanium and the like can be mentioned.

Examples of the organosilicon compound include silicone oil. Preferred silicone oils are those having a viscosity of about 30 to 1,000 centistokes at 25 ° C., such as dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil. Silicone oil and the like are preferred.

Further, pigments or dyes such as conventionally known carbon black and copper phthalocyanine can be used as a coloring material that can be added to the toner for developing an electrostatic image according to the present invention.

The toner for developing an electrostatic image of the present invention is characterized by containing a charge control agent. In the case of a negatively chargeable toner, a metal complex salt of a monoazo dye, salicylic acid, alkyl salicylic acid, dialkyl salicylic acid or naphthoic acid is used. A negative charge control agent such as a metal complex salt is used.

For example, as the negative charge control agent,

[0185]

[Outside 10]

[0186]

[Outside 11]

[0187]

[Outside 12] The following three types are more effective as negative charge control agents combined with the magnetic iron oxide used in the present invention.

[0188]

[Outside 13] [Wherein, X ₁ and X ₂ represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group or a halogen atom, m and m ′ each represent an integer of _{1 to 3} , and Y ₁ and Y ₃ represent a hydrogen atom. ,
Alkyl C ₁ -C _18, alkenyl group of C ₂ -C _18, a sulfonamide group, a mesyl group, a sulfonic group, carboxy ester group, hydroxy group, an alkoxy group of C ₁ -C _18,
Acetylamino group, a benzoyl group, an amino group or a halogen atom, n and n 'represents an integer of 1 to 3, Y ₂
And Y ₄ represent a hydrogen atom or a nitro group, and may be the same as or different from X ₁ and X ₂ , m and m ′, Y ₁ and Y ₃ , n and n ′, and Y ₂ and Y ₄ )) A ⁺ is H ⁺ , NA ⁺ , K ⁺ , N
H ⁺ ₄ or a mixed ion thereof is shown. A monoazo iron complex salt represented by the formula:

[0189]

[Outside 14] A compound of an aromatic hydroxycarboxylic acid, an aromatic diol or an aromatic dicarboxylic acid derivative represented by the formula and an iron atom.

[0190]

[Outside 15] [In the formula, Y ¹ and Y ² represent a phenyl group, a naphthyl group or an anthryl group, and R ₁ and R ₂ represent a halogen atom, a nitro group, a sulfonic group, a carboxyl group, a carboxylate group, a cyano group, a carbonyl group. Represents an alkyl group, an alkoxy group or an amino group, and R ³ and R ⁴ represent a hydrogen atom, an alkyl group, an alkoxy group, a phenyl group optionally having a substituent, an aralkyl group optionally having a substituent or an amino group. R ⁵ and R ^{6 each} represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, k and j each represent an integer of 0 to 3 (not simultaneously 0), and m and n represent 1 or 2 Show.

However, Y ¹ , Y ² , R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , k and j, and m and n may be the same or different. A NN'-bisarylurea derivative represented by the formula:

In particular, the following formula

[0193]

[Outside 16] Is particularly preferable.

It has been confirmed that the use of the above-described negative charge control agent and a polymer component having an adjusted acid value prevents or suppresses image quality characteristics, particularly fog.

Specific examples of the positive charge control agent include, for example,
Modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and oniums such as phosphonium salts which are analogs thereof Salts and lake pigments thereof; triphenylmethane dyes and lake pigments thereof (phosphorotungstic acid, phosphomolybdic acid, phosphomolybdic molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferricyanide) Metal salts of higher fatty acids, metal complexes of acetylacetone; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate DOO, a diorgano tin borate such as dicyclohexyl tin borate, may be used in combination singly, or two or more kinds. Of these, charge control agents such as nigrosine and quaternary ammonium salts are particularly preferably used.

The amount of the charge control agent to be used is 0.1 to 100 parts by weight of the binder resin in terms of the charge amount of the toner.
5.0 parts by weight are preferred.

The toner for developing an electrostatic image of the present invention is preferably mixed with an inorganic fine powder or a hydrophobic inorganic fine powder. For example, it is preferable to use silica fine powder or titanium oxide fine powder alone or in combination.

The fine silica powder used in the present invention includes both a so-called dry method produced by the vapor phase oxidation of a silicon halide and a so-called fumed silica and a so-called wet silica produced from water glass. Although it can be used, fumed silica having few silanol groups on the surface and inside and having no production residue is preferable.

Further, the silica fine powder used in the present invention is preferably subjected to a hydrophobic treatment. The hydrophobizing treatment is applied by chemically treating with an organic silicon compound or the like which reacts or physically adsorbs with the silica fine powder. A preferred method is to treat the dry silica fine powder produced by the vapor phase oxidation of the silicon halide compound with a silane coupling agent or simultaneously with the silane coupling agent and an organic silicon compound such as silicone oil. Is mentioned.

Examples of the silane coupling agent used in the hydrophobic treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, and allylphenyl. Dichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane,
Chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldi Siloxane and 1,3-diphenyltetramethyldisiloxane.

Examples of the organosilicon compound include silicone oil. Preferred silicone oils are those having a viscosity of about 30 to 1,000 centistokes at 25 ° C., such as dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil. Silicone oil and the like are preferred.

The silicone oil treatment method may be, for example, the silica fine powder treated with a silane coupling agent and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or the silicone oil may be mixed with the base silica. May be injected. Alternatively, it may be prepared by dissolving or dispersing a silicone oil in an appropriate solvent, mixing with a base silica fine powder, and removing the solvent.

Further, a preferred system for hydrophobizing silica fine powder used in the present invention is a method of preparing by treating with dimethyldichlorosilane, then with hexamethyldisilazane, and then with silicone oil. No.

As described above, it is preferable to treat the silica fine powder with two or more silane coupling agents and then treat the oil with oil, since the degree of hydrophobicity can be effectively increased.

[0205] The hydrophobizing treatment of the silica fine powder and the oil treatment of the titanium oxide fine powder can also be used in the present invention, and it is preferable as in the case of silica.

If necessary, an external additive other than the silica fine powder may be added to the toner for developing an electrostatic image in the present invention.

For example, a charge auxiliary agent, a conductivity-imparting agent, a fluidity-imparting agent, an anti-caking agent, a release agent for fixing with a hot roll,
These are resin fine particles and inorganic fine particles that function as a lubricant, an abrasive and the like.

The fine resin particles have an average particle size of 0.1.
The polymerizable monomer constituting the resin is preferably styrene / o-methylstyrene / m-methylstyrene / p-methylstyrene / p-methoxystyrene / p-ethylstyrene. Styrene monomers, methacrylic acids such as acrylic acid and methacrylic acid,
Methyl acrylate / ethyl acrylate / acrylic acid n-
Butyl, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate
Acrylic esters such as 2-chloroethyl acrylate / phenyl acrylate, methyl methacrylate / ethyl methacrylate / n-propyl methacrylate / n-butyl methacrylate / isobutyl methacrylate / n-methacrylic acid
-Octyl / dodecyl methacrylate / methacrylic acid 2-
Methacrylates such as ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and other acrylonitrile, methacrylonitrile,
And monomers such as acrylamide.

As the polymerization method, suspension polymerization, emulsion polymerization,
Soap-free polymerization and the like can be used, but more preferably particles obtained by soap-free polymerization are preferred.

In particular, it has been confirmed that resin fine particles having the above-described characteristics have a great effect on drum fusion in a contact charging system such as a roller, brush or blade as a primary charging device.

As other fine particles, for example, a lubricant such as Teflon, zinc stearate, and polyvinylidene fluoride, among which polyvinylidene fluoride is preferable. Alternatively, abrasives such as cerium oxide, silicon carbide, and strontium titanate, among which strontium titanate is preferable. Alternatively, for example, a fluidity imparting agent such as titanium oxide and aluminum oxide, particularly a hydrophobic agent is preferable. A small amount of a caking preventing agent or a conductivity-imparting agent such as carbon black, zinc oxide, antimony oxide, and tin oxide, or white and black fine particles of opposite polarity can also be used as a developability improver.

The resin fine particles, inorganic fine powder, or hydrophobic inorganic fine powder mixed with the toner may be used as the magnetic toner 100.
0.1 to 5 parts by weight (preferably 0.1 to 5 parts by weight)
To 3 parts by weight).

To prepare an electrostatic image developing toner for developing an electrostatic image according to the present invention, the polymer component of the present invention and a pigment, dye or magnetic material as a colorant, a charge controlling agent, Additives, etc. are sufficiently mixed by a mixer such as a ball mill, and then heated, rolled, kneaded, and extruded.
A pigment or dye is dispersed or dissolved in a resin kneaded by melting, kneading and kneading using a hot kneading machine such as a kneader, and after cooling and solidifying, pulverization and strict classification are carried out. Can be obtained.

As another method for obtaining the toner for developing an electrostatic image according to the present invention, the toner can be produced by a polymerization method. The suspension polymerization toner uniformly dissolves or dissolves the polymerizable monomer, the charge control agent of the present invention, the pigment or dye, the magnetic iron oxide, and the polymerization initiator (and, if necessary, the crosslinking agent and other additives). After dispersing into a monomer composition, this monomer composition or a prepolymerized version of this monomer composition is placed in a continuous phase (for example, water) containing a dispersion stabilizer with a suitable stirrer. And a polymerization reaction is carried out at the same time to obtain toner particles having a desired particle size. When the magnetic iron oxide used in the present invention is used in the polymerization method, it is preferable to perform a hydrophobic treatment in advance.

The magnetic iron oxide having a silicon element according to the present invention is produced, for example, by the following method.

Ferrous salt aqueous solution and Fe in the ferrous aqueous solution
Magnetite by passing an oxygen-containing gas through a ferrous salt reaction aqueous solution containing a ferrous hydroxide colloid obtained by reacting 0.90 to 0.99 equivalents of an aqueous alkali hydroxide solution with respect to ²⁺ In producing the particles, the total content of the water-soluble silicate in advance in either the alkali hydroxide aqueous solution or the ferrous salt containing the ferrous hydroxide colloid in terms of silicon element relative to iron element ( 0.4 ~
2.0 to 100% by weight, and 85 to 100 ° C.
An oxygen-containing gas is passed while heating in the temperature range described above to cause an oxidation reaction, whereby magnetic iron oxide particles containing a silicon element are generated from the ferrous hydroxide colloid.
Thereafter, 1.00 equivalent or more of the aqueous alkali hydroxide solution and the remaining water-soluble silicate relative to Fe ²⁺ remaining in the suspension after the completion of the oxidation reaction, that is, the total content (0.4 to
2.0% by weight), and 85-1%
An oxidation reaction is performed while heating in a temperature range of 00 ° C. to generate magnetic iron oxide particles containing silicon element.

Next, in the case of treatment with aluminum hydroxide, a water-soluble aluminum salt is added to the formed particles in the alkaline suspension in which the magnetic iron oxide particles containing the silicon element are formed in terms of aluminum element. After being added to be 0.01 to 2.0% by weight, the pH is adjusted to a range of 6 to 8, and aluminum hydroxide is precipitated on the surface of the magnetic iron oxide. Then, the magnetic iron oxide of the present invention is obtained by filtering, washing with water, drying and crushing. Further, as a method for adjusting the smoothness and the specific surface area to the preferable ranges of the present invention, it is preferable to perform compression, shearing, and spatula using a mix muller or a grinder.

Examples of the silicate compound to be added to the magnetic iron oxide used in the present invention include commercially available silicates such as sodium silicate and silicic acids such as sol silicic acid generated by hydrolysis or the like.

As the water-soluble aluminum salt to be added, aluminum sulfate and the like are exemplified.

As the ferrous salt, iron sulfate generally produced as a by-product in the production of titanium sulfate, iron sulfate produced as a by-product of cleaning the surface of a steel sheet, and iron chloride and the like can be used. .

An example of an image forming apparatus is schematically shown in FIG.
Based on this, the image forming method will be described.

Reference numeral 1 denotes a rotating drum-shaped electrostatic latent image carrier, around which a primary charging device 2, an exposure optical system 3, a developing device 4 having a toner carrier 5, a transfer device 9, and a cleaning device 11 are provided. Are located.

In this image forming apparatus, the surface of the electrostatic latent image carrier 1, which is a photosensitive member, is uniformly charged by the primary charging device 2, and the surface of the electrostatic latent image carrier is exposed by the exposure optical system 3. An electrostatic latent image is formed on the surface of the image forming apparatus 1.

Next, a toner coat layer is formed on the surface of the toner carrier 5 containing the magnet by the toner layer thickness regulating member 6 based on the structure of the present invention, and the conductive portion of the electrostatic latent image carrier 1 is developed in the developing section. The electrostatic latent image formed on the electrostatic latent image carrier 1 is developed while applying an alternate bias, a pulse bias, and / or a DC bias by the bias applying means 8 between the conductive substrate and the toner carrier 5.

The developed toner image is conveyed to the transfer paper P, and the transfer device 9 and the voltage applying means 10 apply an electric charge having a polarity opposite to that of the toner from the back surface of the transfer paper P to be electrostatically transferred to the transfer paper P. .

The fixed image is obtained by passing the transfer paper P on which the toner has been transferred through the heating / pressing roller fixing device 12.

The magnetic toner remaining on the latent image carrier after the transfer step is removed by the cleaning device 11, and the steps following the primary charging are repeated again.

[0228]

EXAMPLES The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

Preparation of resin composition Synthesis of low molecular weight polymer (L-1) 300 parts by weight of xylene was charged into a four-necked flask, and the inside of the vessel was sufficiently purged with nitrogen while stirring, and then heated. To reflux.

Under the reflux, a mixture of 75 parts by weight of styrene, 18 parts by weight of n-butyl acrylate, 7 parts by weight of monobutyl maleate and 2 parts by weight of di-tert-butyl peroxide was added dropwise over 4 hours. Thereafter, the mixture was held for 2 hours to complete the polymerization, thereby obtaining a low molecular weight polymer (L-1) solution.

A portion of the polymer solution was sampled,
The polymer was dried under reduced pressure, and the obtained low molecular weight polymer (L-1) was obtained.
Was measured for GPC and glass transition point (Tg), as a result, weight average molecular weight (Mw) = 9,600, number average molecular weight (Mn) = 6,000, and peak molecular weight (PMw) =
8,500, Tg = 62 ° C., acid value 25.

The conversion of the polymer at this time was 97%.

Synthesis of high molecular weight polymer (H-1) 180 parts by weight of degassed water and 20 parts by weight of a 2% by weight aqueous solution of polyvinyl alcohol were charged into a four-necked flask, and then 70 parts by weight of styrene and acrylic acid 25 parts by weight of n-butyl, 5 parts by weight of monobutyl maleate, 0.005 parts by weight of divinylbenzene, and 2,2-bis (4,4-di-t
A mixture of 0.1 parts by weight of tert-butylperoxycyclohexyl) propane (half-life 10 hours, temperature: 92 ° C.) was added, and stirred to form a suspension.

After sufficiently replacing the inside of the flask with nitrogen, 8
The temperature was raised to 5 ° C. to initiate polymerization. After maintaining at the same temperature for 24 hours, 0.1 part by weight of benzoyl peroxide (half-life of 10 hours; temperature of 72 ° C.) was additionally added. Further, the polymerization was completed by holding for 12 hours.

To the suspension after the completion of the reaction, an aqueous NaOH solution equivalent to 6 times the acid value (AV = 7.8) of the obtained high molecular weight polymer (H-1) was added, and the mixture was stirred for 2 hours. Was.

The high molecular weight polymer (H-1) was separated by filtration, washed with water, dried, and analyzed.
Mw = 1.2 million, Tg = 62 ° C., acid value 6

Preparation of Binder In a four-necked flask, 100 parts by weight of xylene, 25 parts by weight of the high molecular weight polymer (H-1), and 4 parts by weight of polypropylene (Mw = 6,000) were charged, and the temperature was raised. Then, the mixture is stirred under reflux to perform preliminary dissolution. After maintaining in this state for 12 hours, a uniform pre-dissolved solution (Y-1) of the polymer (H-1) and the polypropylene was obtained.

A part of the pre-dissolved solution was sampled,
The solid was dried under reduced pressure and the glass transition point of the obtained solid was measured.

On the other hand, the low molecular weight polymer (L-
300 parts by weight of the homogeneous solution of 1) is introduced and refluxed.

After the above pre-dissolved solution (Y-1) and the low molecular weight polymer (L-1) solution were mixed under reflux, the organic solvent was distilled off, and the obtained resin was cooled, solidified and pulverized. A toner resin composition 1 was obtained.

Analysis of the resin 1 showed that PMw = 11
The area ratio in the molecular weight distribution of GPC of the resin composition having a molecular weight of 100,000 and 1,000,000 or more is 9.2%, Tg = 62.5 ° C.,
The THF insoluble content was 2.1% by weight.

Similarly, the amounts of monobutyl maleate, styrene, n-butyl acrylate and the amount of initiator were adjusted to obtain resin compositions 2 to 4 and comparative resin composition 1 shown in Table 1.
~ 4.

[0243]

[Table 1]

Production of Magnetic Iron Oxide Particles An aqueous solution of ferrous sulfate was mixed with 0.95 equivalent of an aqueous solution of sodium hydroxide relative to Fe ²⁺ , and then mixed with Fe (OH) _2.
The ferrous salt aqueous solution containing was produced.

Thereafter, sodium silicate was added so as to be 1.0% in terms of silicon element with respect to iron element. Next, air was passed through the aqueous ferrous salt solution containing Fe (OH) ₂ at a temperature of 90 ° C. to cause an oxidation reaction, thereby producing magnetic iron oxide particles containing a silicon element.

Further, 0.1% of sodium silicate was added to this suspension.
1.05 equivalents of an aqueous solution of sodium hydroxide in which (silicon element conversion with respect to iron element) is dissolved with respect to the remaining Fe ²⁺ , and while further heating at a temperature of 90 ° C., oxidize and contain silicon element Magnetic iron oxide particles were produced.

The produced magnetic iron oxide particles are washed, filtered, and dried by a conventional method, and then the aggregated magnetic iron oxide particles are subjected to a crushing treatment (consolidation crushing treatment using a mix muller).
Magnetic iron oxide particles 1 were obtained. The particle size was 0.21 μm, the content of silicon element was 1.09%, and the amount of surface SiO _{2 was} 0.19.
%, Smoothness 0.53, bulk density 1.10 g / cm ³ , BE
T specific surface area 10.0 m ² / g, total pore volume 1.1 × 10
^-2 ml / g, micropore specific surface area 4.8 m ² / g, mesopore specific surface area 5.3 m ² / g.

Production of toner Resin composition 1 100 parts by weight Magnetic iron oxide 1 100 parts by weight Negative charge control agent (following formula) 2 parts by weight

[0249]

[Outside 17]

The above mixture was melt-kneaded with a twin-screw extruder heated to 140 ° C., and the cooled kneaded material was coarsely ground with a hammer mill, and the coarsely ground material was finely ground with a jet mill. Was classified with a fixed wall type air classifier to produce a classified powder. Further, the obtained classified powder is strictly classified and removed at the same time by a multi-division classifier (Elbow jet classifier manufactured by Nippon Steel Mining Co., Ltd.) utilizing the Coanda effect to remove the ultrafine powder and the coarse powder at the same time to obtain a weight average particle diameter (D4) 6. 0.7 μm (particle size 12.7
A negatively chargeable magnetic toner having a magnetic toner particle content of 0.2 μm) was obtained. G of the resin composition of the obtained magnetic toner
FIG. 2 shows a PC chart.

100 parts by weight of this magnetic toner, 1.2 parts by weight of hydrophobic silica fine powder (BET 300 m ² / g) treated with dimethyldichlorosilane, treated with hexamethyldisilazane, and then treated with dimethylsilicone oil. And styrene-acrylic microparticles (average particle size: 0.05 μm) obtained by soap-free polymerization were mixed with a Henschel mixer to prepare a magnetic developer (toner No. 1).

Toners 2 to 4 and Comparative Toners 1 to 4 were prepared in the same manner except that the type of resin used and the amount of magnetic iron oxide were changed. The correspondence between the toner and the resin used,
Table 2 shows the compounding amount of the magnetic iron oxide, the physical properties of the resin components when the toner was formed, and the true toner density. Table 3 shows the acid value of the low-molecular component and the high-molecular component and the acid value / total acid value when the toner was formed.

[0253]

[Table 2]

[0254]

[Table 3]

Example 1 Using toner 1, a laser beam printer LBP-A304GII manufactured by Canon was remodeled from a printing speed of 8 sheets / min to a printing speed of 25 sheets / min, and image output was evaluated. At this time, the process speed was 110 mm / sec.

As the toner carrier, a sleeve (center line average roughness Ra = 2.4) obtained by spray-coating a resin in which carbon black and graphite were dispersed on an aluminum base was used, and a urethane elastic blade was applied with a sleeve linear pressure of 20 g. /
cm to control the thickness of the toner layer. The coating amount per unit area of the thin toner layer on the toner carrier in the initial stage was set to 2.1 mg, and w / ρ at that time was 1.
21, the height of the toner layer is about 140 μm at the highest
m.

An OPC drum was used as the electrostatic latent image carrier, and its peripheral speed was 110 mm / sec. The peripheral speed of the developing sleeve set at a distance of 300 μm from the OPC drum was set to 132 mm / sec. The magnification of the peripheral speed was 1.2 times.

The photosensitive drum is primarily charged to V _D = −700 V, and the surface thereof is scanned with a laser beam of a minute spot in accordance with an image pattern to form an electrostatic latent image of V _L = −700 V. Bias f = 1800Hz, V
_pp = 1400V and DC bias _VDC = -500V
Was applied between the developing sleeve carrying the toner and the electrostatic latent image on the OPC surface to form a magnetic toner image.

The formed magnetic toner image is applied to a transfer roller having a conductive elastic layer having a surface rubber hardness of 27 ° with a contact pressure of 5 °.
A transfer device applied to the OPC drum at 0 g / cm ² applied a positive charge from the back of the transfer paper to transfer the image, and then passed through a heating / pressing roller fixing device to obtain a fixed image.

At this time, the surface temperature of the heating roller of the heating / pressing roller fixing device was set to 180 ° C., the total pressure between the heating roller and the pressure roller was set to 5.5 kg, and the nip was set to 4 mm.

Under the above set conditions, low temperature and low humidity (15 ° C./1
0% RH environment and high temperature and high humidity (32.5 ° C / 85%)
RH) An image output test was performed in an environment. The print speed was 2 sheets / 20 sec.

In a low-temperature, low-humidity environment, after taking an initial sample, 9 solid blacks of 5 mm square (3 rows, 3
100 images were continuously printed to obtain images for evaluation of fixability. Thereafter, the durability of 20,000 sheets was performed while successively supplying toner.

In a high-temperature, high-humidity environment, after 5,000 images have been printed, the image is left for 2 days in the same environment, and then 500
Zero images were drawn.

<Evaluation> (1) Image Density An image of 9 pieces (3 rows and 3 rows) of 5 mm square solid black was printed on ordinary plain paper for copying (75 g / m ² ), and a “Macbeth reflection densitometer” was used. (Manufactured by Macbeth Co., Ltd.), the relative density with respect to the print image of the white background portion where the document density was 0.00 was measured.

(2) Fog Using a “Reflectometer” (manufactured by Tokyo Denshoku Co., Ltd.), the whiteness of the transfer paper before printing was measured in advance, and a solid white image printed every 1000 sheets under a low-temperature and low-humidity environment The value at one point at which the difference from the whiteness of the sample was maximum was recorded.

(3) Fixing property In a low-temperature and low-humidity environment, 5
100 images of 9 mm square solid black (3 rows, 3 rows)
Using the printed sample, the fixed image was rubbed with a soft thin paper under a load of 50 g / cm ² , and the worst value of the decrease in image density before and after rubbing was evaluated as follows.

◎ (excellent): less than 5% ○ (good): 5% to less than 10% Δ (acceptable): 10% to less than 20% × (impossible): 20% or more

(4) Offset Resistance The offset resistance was evaluated by printing out a sample image having an image area ratio of about 5% and evaluating the degree of stain on the image.

◎ (excellent): not generated. （(Good): slightly generated. （(Acceptable): slightly generated. X (impossible): remarkable stain on the image.

(5) Stain on Sleeve After completion of the printout test, the state of fixation of the residual toner on the surface of the developing sleeve and the effect on the printout image were visually evaluated.

A: Very good (not generated) A: Good (almost no occurrence) C: Practical (there is sticking, but there is little effect on the image) C: Not practical (a lot of sticking, image unevenness Arises)

(6) Drum Stain The occurrence of scratches on the surface of the photosensitive drum and the adhesion of residual toner and the effect on printout images were visually evaluated.

◎: very good (not generated) 良好: good (slight flaws are seen, but there is no effect on the image) Δ: practical (there are sticking and flaws, but the effect on the image is poor) X): Impossible (many sticks, causing vertical streak-like image defects)

The above results are summarized in Table 4.

Examples 2 to 9 w / ρ was adjusted by using sleeves having different center line average roughnesses (Ra). Further, the peripheral speed ratio of the toner carrier / latent image carrier and the toner were as shown in Table 4. Example 1 except for changing to
The evaluation was performed in the same manner as described above.

Table 4 summarizes the results.

The results of Examples 1 to 9 all show the fixing property,
Excellent results were obtained, including excellent offset resistance, excellent density durability in each environment, and low fog level.

Comparative Examples 1 to 9 As shown in Table 4, the evaluation was performed in the same manner as in Example 1 except that w / ρ, the toner carrier / latent image carrier peripheral speed ratio, and the toner were changed.

Table 4 summarizes the results.

The results of Comparative Examples 4 to 9 all show the fixing property,
At least one of the following items was insufficient: offset resistance, sleeve contamination, density durability in any environment, and fog.

[0281]

[Table 4]

[0282]

As described above, according to the present invention, by adjusting the molecular weight of the polymer component and the acid value of the low molecular weight component and the high molecular weight component in the toner composition, it is possible to fix the toner at a lower temperature than before. It has excellent anti-offset properties, and is resistant to mechanical loads and hardly adheres. Therefore, deterioration due to toner fusion to the toner carrier, electrostatic latent image carrier, etc. It is possible to use a process condition in which deterioration of the toner is small and a load is applied to the toner, and enables long-term durability, environmental stability, and reduction of fog.

[Brief description of the drawings]

FIG. 1 is a view schematically showing an example of an image forming apparatus used in an image forming method of the present invention.

FIG. 2 is a diagram showing a GPC chart.

[Explanation of symbols]

 Reference Signs List 1 latent image carrier 2 primary charging device 3 exposure optical system 4 developing device 5 toner carrier 6 toner layer thickness regulating member 7 toner stirring device 8 developing bias power supply 9 transfer device 10 transfer current generator 11 cleaning device 12 fixing device 13 Magnetic toner

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaichiro Katada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Koichi Toyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-6-194873 (JP, A) JP-A-5-173366 (JP, A) JP-A-5-313421 (JP, A) JP-A-6-110324 (JP, A) A) JP-A-1-214876 (JP, A) JP-A-5-72801 (JP, A) JP-A-61-155464 (JP, A) JP-A-6-194869 (JP, A) JP-A-1 -231060 (JP, A) JP-A-4-204854 (JP, A) JP-A-4-190245 (JP, A) JP-A-6-75427 (JP, A) JP-A-4-70885 (JP, A) JP-A-4-70890 (JP, A) JP-A-61-123853 (JP, A) JP-A-6-138701 (JP, A) JP-A-4-211272 (JP, A) JP-A-5-53373 (JP, A) JP-A-2-256075 (JP, A) (58) Int.Cl. ⁷ , DB name) G03G 9/087 G03G 9/083 G03G 9/097 G03G 15/08 501 G03G 15/08 507

Claims (17)

(57) [Claims] 1. A thin layer of magnetic toner which does not contact a latent image carrier is formed on a toner carrier disposed at a certain distance from an electrostatic latent image carrier, and further formed on the toner carrier. In an image forming method including a step of developing an electrostatic latent image on an electrostatic latent image carrier with the magnetic toner while applying an alternating electric field between the latent image carriers, a magnetic layer formed on the toner carrier is formed. The coating amount per unit area of the toner thin layer is: w / ρ = 0.5 to 1.4 w; toner coating weight per 1 cm ^{2 of} toner carrier surface (mg) ρ; toner true density (g / cm ³ ) And the moving speed of the toner carrier surface in the developing area is 1.05 to 2.0 times the moving speed of the electrostatic latent image carrier surface. Contains coalescing component, magnetic substance and charge control agent The polymer component of the composition has a molecular weight of 3 × in a GPC chromatogram of a) a THF-soluble component of the polymer component, which is substantially free of a THF-insoluble component. It has a main peak in the region of 10 ^{3 to} 3 × 10 ⁴ , and has a molecular weight of 1 × 10 ^{5 to} 3 × 10 ^6.
And c) the ratio of the acid value to the total acid value (acid value / total acid value) is 0.7 or less.
And the acid value (A _VL ) of the low molecular weight polymer (region having a molecular weight of less than 5 × 10 ⁴ in the GPC chromatogram) is 2
1 to 35 mgKOH / g, and a high molecular weight polymer (GP
In the C chromatogram, the acid value (A _VH ) of the region having a molecular weight of 5 × 10 ⁴ or more is 0.5 to 11 mgKOH / g.
There, and an image forming method characterized in that relationship of the difference satisfies the _{10 ≦ (A VL -A VH)} ≦ 27. 2. The image forming method according to claim 1, wherein the GPC chromatogram of the THF-soluble component of the polymer component of the composition has a minimum value in a region having a molecular weight of 3 × 10 ⁴ or more and less than 1 × 10 ^5. . 3. The composition has a Tg of 50 to 70 ° C.
The image forming method according to claim 1 or 2 and Tg _H of Tg _L and a high molecular weight polymer having a low molecular weight polymer satisfies the following condition Tg _L ≧ Tg _H -5 of the composition. 4. The composition has a Tg of 55 to 65 ° C.,
The image forming method according to any one of claims 1 to 3 and Tg _H of Tg _L and a high molecular weight polymer having a low molecular weight polymer satisfies the following condition Tg _L ≧ Tg _H of the composition. 5. The image forming method according to any one of claims 1 to 4 polymer component of the composition satisfies the following formula. [Outside 1] Wherein, W _L is the abundance of low-molecular weight polymer component (wt%)
W _H represents the abundance (% by weight) of the high molecular weight polymer component, A _VL represents the acid value of the low molecular weight polymer component (mg KOH / g), and A _VH represents the acid value of the high molecular weight polymer component. Value (mgKOH /
g). ] 6. The composition according to claim 1, wherein both the low molecular weight polymer component and the high molecular weight polymer component of the composition contain at least 65 parts by weight of a styrene monomer component unit. 5. The image forming method according to any one of 5 . 7. A high molecular weight polymer component of the composition is polymerized polymer with a polyfunctional polymerization initiator claims 1 to 6
The image forming method according to any one of the above. 8. according to any one of claims 1 to 6 high molecular weight polymer component is a polyfunctional polymerization initiator and a monofunctional polymerization initiator at least in combination with polymer produced of the composition Image forming method. Magnetic body 9. The composition is a magnetic iron oxide particles, the image forming method according to any one of claims 1 to 8 magnetic iron oxide particles contain silicon element. 10. The image forming method according to claim 9 , wherein the magnetic iron oxide particles have a silicon element content of 0.1 to 2.0% by weight based on the iron element. 11. The magnetic iron oxide particles have Si on their surface.
The image forming method according to claim 9 or 10 O ₂ silicon oxide 0.01 to 1.00% by weight in terms exist. 12. The magnetic iron oxide particles have a smoothness of 0.3 to 0.3.
The image forming method according to any one of claims 9 to 11 is 0.8. 13. The magnetic iron oxide particles have a bulk density of 0.8 g.
The image forming method according to any one of claims 9 to 12 , wherein the density is not less than / cm ³ . 14. The magnetic iron oxide particles having a specific surface area of 15.
The image forming method according to any one of claims 9 to 13 , wherein the amount is 0 m ² / g or less. 15. magnetic iron oxide particles, the image formation according to any one of claims 9 to 14 the total pore volume is ^{7.0 × 10 -3 ~15.0 × 10 -3} m1 / g Method. 16. The charge controlling agent has the following general formula: [Wherein, X ₁ and X ₂ represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, or a halogen atom, m and m ′ each represent an integer of _{1 to 3} , and Y ₁ and Y ₃ represent hydrogen atom, an alkyl group of C ₁ ~C _18, C ₂ ~
A C ₁₈ alkenyl group, a sulfonamide group, a mesyl group, a sulfonic acid group, a carboxyester group, a hydroxy group,
₁ -C ₁₈ alkoxy group, an acetylamino group, a benzoyl group, an amino group, or a halogen atom, n and n 'represents an integer of 1 to 3, Y ₂ and Y ₄ represents a hydrogen atom or a nitro group (X ₁ and X ₂ , m and m′Y ₁ and Y ₃ , n and n ′, Y ₂
And Y ₄ may be the same or different. ) A ⁺ is H ⁺ , N
^{a +, K +, NH +} 4 or the image forming method according to any one of claims 1 to 15, characterized in that indicated in those showing a mixed ion of. 17. The charge control agent represented by the following general formula: The image forming method according to claim 16 , wherein: