JPH06332237A - Two-component developer - Google Patents

Abstract

PURPOSE:To provide a two-component developer which is easily transported in a developing device and capable of forming a high-quality picture over a long period. CONSTITUTION:This two-component developer contains a toner having a fine titanium oxide particle and a carrier. The weight average diameter of the toner is controlled to 3-7mum, the particle size distribution is specified, the saturation magnetization in the impressed magnetic field of 3000 oersteds is adjusted to 50-90emu/g, the residual magnetization to <=10emu/g and the coercive force to <=40 oersteds, and the fluidity of the developer is controlled to 25-55 (sec/50g).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called two-component developer in which a small amount of toner is dispersed in a medium called a carrier, and more particularly to a two-component developer having markedly improved image quality and durability.

[0002]

2. Description of the Related Art In recent years, with the widespread use of image forming apparatuses such as electrophotographic copying machines, their applications have been widespread, and demands for high definition and high image quality have been increasing in the market. In the technical field, attempts have been made to reduce the particle size of the toner to achieve high image quality, but when the particle size becomes finer, the surface area per unit weight increases, and the amount of electrification of the toner tends to increase. Yes, there is concern about low image density and deterioration of durability. In addition, since the amount of electrification of the toner is large, the adhesion between the toners is strong, the fluidity is lowered, and problems occur in stability of toner replenishment and tribo application to the replenishment toner.

In the case of color toner, a magnetic material,
Since it does not contain a conductive substance such as carbon black, there is no part that leaks charge, and the amount of electricity generally tends to increase. This tendency is more remarkable when a polyester binder having high charging performance is used.

Up to now, several developers have been proposed for the purpose of improving the image quality. JP-A-5
Japanese Patent Laid-Open No. 1-3244 proposes a non-magnetic toner intended to improve the image quality by regulating the particle size distribution. Among the toners, the toner having a particle size of 8 to 12 μm is mainly used, and it is relatively coarse. According to the study of the present inventors, it is difficult for the toner to have a uniform “paste” on the latent image. Further, from the characteristics that 5 μm or less is 30 number% or less and 20 μm or more is 5 number% or less, the point that the particle size distribution is broad also tends to deteriorate the uniformity.
In order to form a clear image using a toner having such a coarse toner particle and a broad particle size distribution, the toner particles are superposed in a thick manner to fill the gaps between the toner particles to form an apparent image. There is also a problem that it is necessary to increase the image density, and the amount of toner consumption required to obtain a predetermined image density increases.

Further, Japanese Laid-Open Patent Publication No. 54-72054 proposes a non-magnetic toner having a sharper distribution than the former, but the size of particles having an intermediate weight is 8.5 to 8.5.
As a toner having a high resolution of 11.0 μm, there is still room for improvement.

Japanese Unexamined Patent Publication (Kokai) No. 58-129437 proposes a non-magnetic toner having an average particle size of 6 to 10 μm and a maximum number of particles of 5 to 8 μm, but particles of 5 μm or less are 15% by number or less. There is little, and there is almost no effect in terms of sharpness.

According to the studies made by the present inventors, it was found that toner particles of 5 μm or less clearly reproduce the contour of the latent image and have a main function of fine toner paste on the entire latent image. Was done. In particular, in the electrostatic latent image on the photoconductor, the electric field lines are concentrated in the electrostatic charge latent image, so the electric field strength is higher at the edge portion that is the contour than inside, and the quality of the toner particles gathering at this portion causes
The sharpness of the image quality is decided. According to the study by the present inventors, 5 μ
It has been found that the amount of particles of m or less is effective for solving the problem of sharpness of image quality.

Therefore, Japanese Patent Application Laid-Open No. 2-222966 proposes a toner containing 15 to 40% by number of toner particles having a size of 5 μm or less. With this, a considerable improvement in image quality is achieved, but further improvement is achieved. Image quality is also desired.

Further, in JP-A-2-877, 5 μm
A toner containing 17 to 60% by number of the following toner particles has been proposed, which certainly stabilizes the image quality and image density, but continuously prints an original that consumes a large amount of toner, such as a photographic original. In such a case, it was also found that it is difficult to always obtain a constant image because the particle size distribution of the toner is changed only by taking measures as the toner.

On the other hand, as an indication of the average particle size and particle size distribution of the carrier, JP-A-51-3238, JP-A-58-144839, and JP-A-61-20464 have been proposed.
There is No. 6 publication. JP-A-51-3238 refers to a rough particle size distribution. However, it does not specifically disclose the magnetic characteristics that are closely related to the developability of the developer and the transportability within the developing device. Further, in all the carriers in Examples, 250 mesh or more is about 80% by weight.
In addition, the average particle diameter is 60 μm or more.

Further, Japanese Unexamined Patent Publication No. 58-144839 discloses only the average particle size, and the amount of fine powder which influences the carrier adhesion to the photoreceptor and the coarse powder which affects the sharpness of the image. The amount is not mentioned, and the distribution is not described in detail in consideration of the characteristics of color reproduction. Further, Japanese Patent Laid-Open No. 61-204646 discloses a combination of a copying machine and a suitable developer as the main point of the invention, and does not specifically describe the particle size distribution or magnetic characteristics of the carrier. Moreover, it does not even disclose why the developer is so effective in the copying machine.

Further, JP-A-49-70630 discloses that
Although the magnetic force of the carrier is described, these are about iron powder having a larger specific gravity than ferrite as the carrier material, and the saturation magnetism is also high. Although many of these iron powder carriers have been used in the past, they have a large specific gravity and are apt to cause a heavy weight of the copying apparatus and overload of driving torque, and have a large environmental dependency.

Further, the ferrite carrier described in JP-A-58-23032 is for a porous material having a large number of pores, and such a carrier is liable to cause an edge effect and has durability. It is scarce and proved to be unsuitable as a color carrier.

Up to now, there has been a demand for a developer capable of continuously copying an image having a large image area with a small amount of the developer and satisfying the characteristic peculiar to color copying in which the edge effect does not occur even after the endurance. ing. Although developers and carriers have been studied, most of them have been proposed in consideration of black-and-white copying, and very few have been proposed as applicable to full-color copying. In addition, a carrier having the ability to continue copying an image having an image area of 20% or more, which is almost similar to a solid image, the reduction of edge effect, and the ability to maintain the uniformity of image density in one copy are Long-awaited.

In view of this, Japanese Patent Application Laid-Open No. 2-281280 proposes a carrier having a narrow particle size distribution in which the amount of fine powder and the amount of coarse powder are controlled to achieve a carrier having improved developing characteristics.

However, as described above, there is an increasing demand in the market for high-definition and high-quality copying machines, and in the technical field, the particle size of toner should be reduced to achieve high-quality color. However, when the particle size becomes finer, the surface area per unit weight increases, and the amount of electrification of the toner tends to increase, and there is a concern that the image density will be low and the durability will be deteriorated.

As described above, it has been attempted to further reduce the diameter of the carrier for the purpose of reducing the image density and preventing the deterioration of durability by reducing the toner particle diameter, or improving the developing efficiency. However, in such a carrier,
The current situation is that sufficient quality has not been obtained to cope with changes in charge amount due to durability.

The present inventors have found that the image density of the image forming method,
As a result of diligent studies on highlight reproducibility and fine line reproducibility, when a toner having a specific particle size distribution and a carrier having a spherical shape are used, excellent image quality excellent in high image density, highlight reproduction, fine line reproduction, etc. It was also found that when specific titanium oxide fine particles are contained as an external additive, the fluidity of the developer can be improved and stable environmental characteristics can be achieved.

First, as an adverse effect that occurs when the carrier and the toner have a small particle size, the fluidity as a developer is lowered, and the developer in the developing device becomes difficult to circulate. As a countermeasure for this, changing the apparatus conditions such as increasing the stirring strength in the developing device can be mentioned, but this is not preferable because it causes a problem such as shortening the durable life of the developer. Therefore, it is important to secure a certain level of fluidity as a developer. Several means can be considered for securing the fluidity of the developer.

The present inventors have found that controlling the shape of the carrier is effective as one of them. That is,
The fluidity is improved by increasing the spherical rate of the carrier particles.

Regarding the spheroidizing of the carrier, JP-A-59-59
As described in JP-A-222847, the definition of the degree of spheroidization is unclear, and it is not possible to know which level actually can be used.

Further, in JP-A-63-41864, the sphericity Ψ _{w of the} carrier is defined.
This applies only to the elastic blade coat developing method and is different from the present invention.

The present inventors have also found that in order to improve the fluidity of the developer, it is effective to further add a resin having a low surface energy to the coating resin of the resin-coated carrier.

What defines the carrier fluidity is
JP-A-63-41865 and JP-A-1-22596
No. 2 publication. However, when using a carrier smaller than the conventional one in the present invention, J
It is difficult to perform measurement by IS-Z2502, and it becomes difficult to obtain reproducibility.

Further, the above publication is limited to the carrier only, and does not include the influence of the chargeability on the toner side and other additives. Therefore, even if the liquidity of the carrier is kept constant, good results are not always obtained in reality. Therefore, it is important to pay attention to the developer fluidity including the chargeability and the influence of the toner surface.

[0026]

SUMMARY OF THE INVENTION An object of the present invention is to provide a two-component developer which solves the above problems.

Further, an object of the present invention is to provide a two-component developer which is clear and has excellent gradation.

A further object of the present invention is to provide a two-component developer having good transportability in the developing device.

A further object of the present invention is to provide a two-component developer which does not change its performance even after long-term use.

A further object of the present invention is to provide a two-component developer having no change in performance with respect to environmental changes.

Further, the object of the present invention is to provide a two-component developer capable of obtaining a high image density with a small consumption amount.

Further, an object of the present invention is to provide a two-component developer capable of forming a toner image excellent in resolution, gradation and fine line reproducibility even in an image forming apparatus using a digital image signal. is there.

[0033]

The present invention provides a two-component developer containing at least a non-magnetic colorant-containing resin particle, a toner having an external additive, and a carrier.

(1) The toner has a weight average particle diameter of 3 to 7 μm, contains more than 40% by number of toner particles having a particle diameter of 5.04 μm or less, and 10 toner particles having a particle diameter of 4 μm or less. ˜70% by number, 2 to 20% by volume of toner having a particle size of 8 μm or more, 1
6% by volume or less of toner having a particle size of 0.08 μm or more is contained,

(2) The carrier has a weight average particle size of 15 to 45 μm, 1 to 20% of carrier particles smaller than 22 μm, 3% or less of carrier particles smaller than 16 μm, and a carrier of 62 μm or more. 2 to 15% of particles, 2% of carrier particles of 88 μm or more
The carrier has a saturation magnetization of 50 to 90 emu / g with respect to an applied magnetic field of 3000 oersteds, a residual magnetization of 10 emu / g or less, and a coercive force of 40 or less.
Below Oersted,

(3) The two-component developer is characterized in that the developer has a fluidity of 25 to 55 (sec / 50 g).

The present invention will be described in more detail.

As the toner, toner particles having a particle diameter of 4 μm or less are 10 to 70% by number of the total number of particles, preferably 15 to
60% by number is good. 1 toner particle having a particle size of 4 μm or less
When the content is less than 0% by number, the number of non-magnetic toner particles effective for high image quality is small, and particularly, as the toner is used by continuing copying or printing out, the effective non-magnetic toner particle component decreases, and the present invention The balance of the particle size distribution of the non-magnetic toner is deteriorated as indicated by, and the image quality may be gradually deteriorated.

On the other hand, if it exceeds 70% by number, the toner particles are likely to aggregate with each other, and a toner lump having a particle size larger than the original particle size is likely to be formed, resulting in a rough image quality, a reduction in resolution, or The density difference between the edge portion and the inside of the latent image becomes large, and the image tends to be a hollow image.

Further, particles of 8 μm or more are 2.0 to 20.0.
It is preferably in volume%, and is preferably 3.0 to 18.0.
Volume% is good. If the amount is more than 20.0% by volume, the image quality is deteriorated, and more than necessary development, that is, excessive toner overload occurs, resulting in an increase in toner consumption. On the other hand, 2.0
When the content is less than the volume%, the image quality may be deteriorated due to the deterioration of fluidity, no matter how the toner formulation is devised.

In order to further improve the effect of the present invention, in order to improve the chargeability and fluidity of the toner,
Particles of 5.04 μm or less are more than 40% by number and 90% by number or less, preferably more than 40% by number and 80% by number
In the following, particles of 10.08 μm or more are 0 to 6% by volume,
It is necessary to set it to preferably 0 to 4% by volume.

On the other hand, the carrier has a weight average particle diameter of 15 to 45 μm, 1 to 20% of carrier particles smaller than 22 μm, preferably 2 to 10%, more preferably 2 to 6%, 16 μm. Smaller carrier particles are 3% or less, preferably 1% or less, more preferably 0.5% or less.

If the amount of the fine powders exceeds the above value, the carrier adhesion and the smooth charging with the toner are hindered, and if the carrier particles smaller than 22 μm is less than 1%, the magnetic brush becomes sparse. The rising of the charging of the toner is also deteriorated, which causes toner scattering and fog.

As described above, the adverse effect that occurs when the carrier and toner have a small particle size is that the fluidity of the developer is lowered, and the developer in the developing device becomes difficult to circulate. As a countermeasure for this, changing the apparatus conditions such as increasing the stirring strength in the developing device can be mentioned, but this is not preferable because it causes a problem such as shortening the durable life of the developer. Therefore, it is important to secure a certain level of fluidity as a developer. It is effective to control the shape of the carrier as a means for ensuring the fluidity of the developer. That is, the fluidity is improved by increasing the spherical rate of the carrier particles.

In the present invention, the shape of the carrier is defined as follows.

First, the carrier is photographed with an SEM (scanning electron microscope) at an appropriate magnification. At this time, with respect to the same particle, several screens in which the electron beam hits the sample stage on which the carrier is perpendicular and a screen in which the electron beam hits as horizontally as possible are drawn, and a rectangular parallelepiped circumscribing one particle is drawn from these. In addition, a>
Set a, b and c so that b> c or a> b = c or a = b> c or a = b = c.
Measure c.

The above operation is randomly performed for at least 20 particles and the average of b / a and c / a is obtained.

In the present invention, the average of b / a is 0.7.
To 1.0 and a carrier having a shape in which the average of c / a falls within the range of 0.6 to 1.0, preferably the average of b / a is 0.8 to 1.0 and c / a. The average of a is 0.
It falls within the range of 7 to 1.0. If the modified carrier is out of the spherical shape beyond this range, problems occur in the fluidity of the developer and the stirring efficiency as described above.

However, the spheroidization rate is increased and c / a is 1
When it is brought close to the above, the cost will usually be considerably high even if the processing conditions such as spheroidization by a spray dry method or high-temperature heat treatment are controlled. It has been found that it is possible to obtain sufficient performance even with a sized carrier.

Generally, it is difficult to increase the spheroidization rate as the carrier has a smaller particle size, but in order to adjust the degree of spheroidization as described above, adjustment of manufacturing conditions, for example, spray drying method is used. When used, the viscosity of the slurry can be adjusted, the temperature and the use of additives can be used, but the method is not particularly limited, and the baking temperature can be adjusted by other methods.

The method of measuring the fluidity of the developer is JIS-Z.
2502, when applied to the small particle size toner and carrier of the present invention, the fluidity of the developer is worse than that of the normal particle size and the funnel holes are apt to be clogged. Therefore, reproducibility and measurement accuracy are extremely deteriorated. Then, as a result of the investigation, the present inventors have found that the diameter of the funnel can be increased and measured to be a preferable determination means.

That is, the desired fluidity of the developer in the present invention is 25 to 55 (second / 50 g). When the time is longer than 55 seconds, the fluidity is poor, charge cannot be smoothly applied to the replenished toner, and image deterioration occurs. If it is less than 25 seconds, a phenomenon in which the developer becomes a small lump and flows is observed, and toner scattering and background fogging occur.

By the way, the carrier is influenced by the magnetic roller incorporated in the developing sleeve due to its magnetic characteristic, and greatly affects the developing characteristic and the transportability of the developer.

The saturation magnetization of the carrier is 50 to 90 emu /
A value of g is excellent in uniformity and gradation reproducibility of images in color copying, which is suitable.

When the saturation magnetization exceeds 90 emu / g (for an applied magnetic field of 3000 oersteds), a brush composed of carrier and toner on the developing sleeve facing the electrostatic latent image on the photoreceptor during development. -Like spikes are tightly tightened, and the reproduction of gradation and halftone is poor. On the other hand, if it is less than 50 emu / g, it becomes difficult to properly hold the toner and the carrier on the developing sleeve, and problems such as carrier adhesion and toner scattering are likely to occur. Further, if the residual magnetization and coercive force of the carrier are too high, the good transportability of the developer in the developing device is hindered, and image defects such as scratches and uneven density in a solid image are likely to occur, and the developing ability is deteriorated. It will be lowered. Therefore, in order to maintain the developability, the residual magnetization is 10 emu / g or less, preferably 5 emu.
/ G or less, more preferably substantially 0 and a coercive force of 4
It is important that it is 0 Oersted or less (3000 Oersted, with respect to the applied magnetic field), preferably 30 Oersteds or less, and more preferably 10 Oersteds or less.

Further, the present invention provides an external additive for toner,
It is also one of the features that it contains at least titanium oxide fine particles. In particular, anatase type titanium oxide fine particles which have been surface-treated while hydrolyzing the coupling agent in an aqueous system are extremely effective in terms of stabilizing charging and imparting fluidity. This cannot be achieved with the commonly known hydrophobic silica as a flow improver.

The reason for this is that the silica fine particles themselves have a strong negative chargeability, whereas the titanium oxide fine particles have a substantially neutral chargeability. Conventionally, it has been proposed to add hydrophobic titanium oxide, but titanium oxide fine particles originally have a smaller surface activity than silica, so that they have not been sufficiently hydrophobized. In addition, when a large amount of treatment agent or the like or a highly viscous treatment agent is used, the degree of hydrophobicity is certainly increased, but coalescence of particles occurs and the fluidity-imparting ability is deteriorated. It was not always possible to achieve both stabilization and liquidity provision.

On the other hand, hydrophobic silica is certainly excellent in its fluidity-providing ability, but when it is contained in a large amount, on the contrary, due to its strong charging property, electrostatic aggregation occurs and the fluidity-providing ability is lowered. I will end up. In that respect, as the amount of titanium oxide increases,
The fluidity of the toner is improved.

The use of anatase-type titanium oxide has been proposed, for example, in Japanese Patent Application Laid-Open No. 60-112052. However, anatase-type titanium oxide has a small volume resistivity of about 10 ⁷ Ωcm and is used as it is. When it was used, the charge leaked quickly especially under high humidity, and it was not always satisfactory in terms of stabilization of charge, and it was necessary to improve it.

Further, as an example of containing a hydrophobized titanium oxide in a toner, Japanese Patent Application Laid-Open No. 59-52255 proposes a toner containing titanium oxide treated with alkyltrialkoxysilane. ,
Although the characteristics of electrophotography are certainly improved, the surface activity of titanium oxide is originally small and coalesced particles are generated at the treatment stage, and the hydrophobicity is not uniform, which is not always satisfactory. It was

The inventors of the present invention have made earnest studies on the stability of the chargeability of the toner. As a result, the average particle diameter of 0.01 to 0.5 was obtained by treating a specific coupling agent while hydrolyzing it in an aqueous system.
It was found that anatase type titanium oxide having a light transmittance of 0.2%, a hydrophobicity of 20 to 98% and a wavelength of 400 nm of 40% or more can be subjected to a uniform hydrophobic treatment and there is no coalescence of particles, and the oxidation thereof is performed. It has been found that a toner containing titanium is extremely effective in terms of stabilizing charging and imparting fluidity.

That is, according to the present invention, the surface treatment is carried out while hydrolyzing the coupling agent while mechanically dispersing the anatase type titanium oxide fine particles in an aqueous system so as to have a primary particle size. It was found that the particles are hardly coalesced with each other, and the charging repulsion between particles is caused by the treatment, and the anatase type titanium oxide fine particles are surface-treated in the state of almost primary particles.

The present invention is characterized in that the surface of titanium oxide is treated while hydrolyzing the coupling agent in an aqueous system. At this time, in order to disperse the titanium oxide fine particles into the primary particles, mechanical force is applied. Since it is added, it is not necessary to use a coupling agent such as chlorosilanes or silazanes that generate a gas, and further, it has not been possible to use particles in a gas phase because they cannot be used together. A viscous coupling agent can also be used, and the effect of hydrophobization is great.

As the coupling agent which can be used in the present invention, any one such as a silane coupling agent and a titanium coupling agent may be used. A silane coupling agent is preferably used, which has a general formula

R _m SiY _n R: Alcooxy group m: integer of 1 to 3 Y: alkyl group Hydrocarbon group containing vinyl group, glycidoxy group, methacryl group n: integer of 1 to 3 Vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxy Examples thereof include silane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane. Particularly preferred is

C _α H _{2α + 1-} Si (OC _β H _{2β + 1} ) ₃ α = 4 to 12 and β = 1 to 3.

Here, when α in the general formula is smaller than 4, the treatment becomes easy, but the hydrophobicity cannot be sufficiently achieved.
On the other hand, when α is greater than 13, the hydrophobicity is sufficient, but the titanium oxide particles are often coalesced with each other and the fluidity-imparting ability is deteriorated. On the other hand, when β is larger than 3, the reactivity is lowered and the hydrophobization is not sufficiently performed. Therefore, in the present invention, α is 4 to 12, preferably 4 to 8 and β is 1
-3, preferably 1-2.

The amount of treatment is 1 to 50 parts by weight, preferably 3 to 40 parts by weight, based on 100 parts by weight of titanium oxide, and the degree of hydrophobicity is 20 to 98%, preferably 30 to 90.
%, More preferably 40 to 80%.

That is, if the degree of hydrophobicity is less than 20%, the amount of charge is greatly reduced by leaving it in high humidity for a long period of time, and a mechanism for promoting charge on the hardware side is required, which complicates the apparatus and makes it hydrophobic. If the degree exceeds 98%, it is difficult to control the charge of titanium oxide itself even if anatase type titanium oxide having a small volume resistivity is used, and as a result, the toner is charged up under low humidity.

The particle size is 0.0 from the viewpoint of imparting fluidity.
1 to 0.2 μm is preferable. When the particle size is larger than 0.2 μm, toner charging becomes non-uniform due to poor fluidity, resulting in toner scattering and fog. Also 0.0
If it is less than 1 μm, the toner is likely to be embedded on the toner surface and the toner is deteriorated quickly, and the durability is deteriorated. This tendency is more remarkable in the sharp melt color toner used in the present invention. The particle size of titanium oxide in the present invention was measured by a transmission electron microscope.

In the present invention, the method of treating titanium oxide is effective by hydrolyzing the coupling agent while mechanically dispersing titanium oxide in an aqueous system so as to have a primary particle size. Therefore, it is preferable in that no solvent is used.

Further, one feature of the present invention is that the treated titanium oxide has a light transmittance of 40% or more at a light length of 400 nm.

That is, the titanium oxide used in the present invention has a very small primary particle diameter of 0.2 to 0.01 μm, but when it is actually contained in the toner, it is not necessarily dispersed in the primary particles. However, it may exist as secondary particles. Therefore, no matter how small the primary particle size is, the effect of the present invention is drastically reduced if the effective particle size that behaves as the secondary particles is large. However, the higher the light transmittance at 400 nm, which is the lower limit wavelength in the visible region, the smaller the secondary particle size, the ability to impart fluidity, the sharpness of the projected image of OHP in the case of color toner, and the like, and the better results are expected. it can. The reason why 400 nm is selected is the boundary region between ultraviolet and visible, and it is said that particles having a particle size of ½ or less of the light wavelength are transmitted.
The transmittance for wavelengths longer than that is naturally large and meaningless.

Further, it was confirmed by X-ray diffraction that the crystal form of titanium oxide was an anatase form having a lattice constant (a) of 3.78Å and a lattice constant (b) of 9.49Å.

On the other hand, as a method of obtaining a hydrophobic titanium oxide having a fine particle diameter, a method of obtaining amorphous spherical titanium oxide by subjecting a volatile titanium alkoxide or the like to low-temperature oxidation to make it spherical and then subjecting it to surface treatment is known. However, considering that the starting materials are expensive and the manufacturing equipment is complicated,
The cost is less than the present invention.

The titanium oxide of the present invention is suitable for satisfying the developer fluidity and obtaining good results.

If the particle size of the toner is reduced, the surface area per weight increases, and excessive charging due to rubbing tends to occur. On the other hand, the effect of titanium oxide fine particles that can control charge and impart fluidity is great. The content of titanium oxide suitable for the present invention is 0.5 to 5% by weight, preferably 0.7 to 3% by weight, more preferably 1.0 to 2.5% by weight.

The toner according to the present invention may contain a charge control agent in order to stabilize the charge characteristics. At that time, a colorless or pale color charge control agent that does not affect the color tone of the toner is preferable. Examples of the negative charge control agent at that time include organic metal complexes such as metal complexes of alkyl-substituted salicylic acid (for example, chromium complex or zinc complex of di-tert-butylsalicylic acid). When the negative charge control agent is blended in the toner, it is 0.1-10 with respect to 100 parts by weight of the binder resin.
It is preferable to add 0.5 part by weight, preferably 0.5 to 8 parts by weight.

When the mixing ratio of the toner according to the present invention and the carrier is 2 to 12% by weight, preferably 3 to 9% by weight as the toner concentration in the developer, a good result is usually obtained. If the toner concentration is less than 2% by weight, the image density is low and it is not practical. If it exceeds 10% by weight, fog and scattering in the machine are increased and the useful life of the developer is shortened.

As the colorant used in the present invention, known dyes and pigments such as phthalocyanine blue, indanthrene blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, benzidine yellow and the like are widely used. can do. The content thereof is 12 parts by weight or less, preferably 0.5 to 9 parts by weight, based on 100 parts by weight of the binder resin so as to sensitively reflect the transparency of the OHP film.

If necessary, the toner of the present invention may be mixed with additives within a range that does not impair the characteristics of the toner. Examples of such additives include Teflon, zinc stearate and polyvinylidene fluoride. Such lubricants, fixing aids (for example, low molecular weight polyethylene, low molecular weight polypropylene, etc.), organic resin particles and the like can be used.

In the production of the toner of the present invention, after the constituent materials are well kneaded by a heat kneader such as a hot roll, a kneader, an extruder or the like, a method of obtaining by mechanical pulverization and classification, or in a binder resin solution After dispersing a material such as a colorant in, a method obtained by spray drying, or
After mixing the predetermined material to the monomer that should constitute the binder resin,
Each method such as a method for producing a polymerized toner in which a toner is obtained by polymerizing this emulsion suspension can be applied.

As the binding substance used in the toner of the present invention, various material resins conventionally known as electrophotographic toner binding resins are used.

For example, polystyrene, styrene-based copolymers such as styrene-butadiene copolymer, styrene-acrylic copolymer, etc., ethylene-based such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer. Examples thereof include copolymers, phenol resins, epoxy resins, acrylic phthalate resins, polyamide resins, polyester resins, maleic acid resins and the like. In addition, the manufacturing method and the like of each resin are not particularly limited.

Among these resins, the effect of the present invention is remarkable when a polyester resin having a high negative chargeability is used. That is, while polyester-based resins have excellent fixability and are suitable for color toners, they have a strong negative charging ability and are prone to excessive charging, but when the polyester resin is used in the constitution of the present invention, the harmful effects are improved and excellent. Toner is obtained.

[0086]

[Chemical 1]

(Wherein R is an ethylene or propylene group, x and y are each an integer of 1 or more, and x +
The average value of y is 2 to 10. ), A bisphenol derivative or a substitution product represented by the formula (1) is used as a diol component, and a carboxylic acid component composed of a carboxylic acid having a valence of 2 or more or an acid anhydride thereof or a lower alkyl ester thereof (eg, fumaric acid, maleic acid, maleic anhydride, phthalate). An acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) is more preferable because it has a sharp melting property.

The carrier used in the developer of the present invention is preferably a resin-coated carrier, and an electrically insulating resin is used as a coating resin for the surface of the carrier, which is appropriately selected depending on the toner material and carrier core material. . In the present invention, at least one monomer selected from acrylic acid (or its ester) monomer and methacrylic acid (or its ester) monomer is used in order to improve the adhesion to the carrier core material surface. It is desirable to contain it, but it is not particularly limited. In particular, when polyester resin particles having a high negative chargeability are used as the toner material, it is preferable to use a copolymer with a styrene-based monomer for the purpose of stabilizing the charge. Is preferably 5 to 70% by weight.

Examples of the monomer for producing the resin for coating the carrier core material which can be used in the present invention include styrene-based monomers such as styrene monomer, chlorostyrene monomer, α-methylstyrene monomer, styrene-chlorostyrene monomer and the like. Examples of the system monomers include acrylic acid ester monomers (methyl acrylate monomer, ethyl acrylate monomer, butyl acrylate monomer, octyl acrylate monomer, phenyl acrylate monomer, 2-ethylhexyl acrylate monomer), and the like, and methacrylic acid ester monomers. (Methyl methacrylate monomer, ethyl methacrylate monomer, butyl methacrylate monomer, phenyl methacrylate monomer) and the like.

Examples of the material for the core material of the carrier used in the present invention include surface-oxidized or non-oxidized metals such as iron, nickel, cobalt, manganese, chromium and rare earths, their alloys or oxides, and magnetic substance dispersions. Resin particles and the like can be used, but ferrite particles are more preferably used than metal oxides.

There are no particular restrictions on the manufacturing method.

When the average particle size of the carrier is less than 4 μm, the carrier is easily developed (transferred together with the toner) on the latent image carrier, and the latent image carrier and the cleaning blade are easily damaged. If the thickness is less than 10 μm, the same tendency is likely to occur due to the difference in development conditions. On the other hand, when the average particle diameter of the carrier is larger than 45 μm, the toner holding ability of the carrier is lowered particularly in combination with the small particle diameter toner of the present invention, and nonuniformity of solid image, toner scattering, fogging and the like occur. Easier to do. Such a carrier core material may be composed of only a magnetic material or a combination of a magnetic material and a non-magnetic material, and is a mixture of two or more kinds of magnetic particles. May be.

The method of coating the surface of the above-mentioned carrier core material with the above-mentioned coating resin is as follows: the resin is dissolved or suspended in a solvent and applied to the surface of the core material, and the above-mentioned resin is composed of magnetic particles and the like. However, a dry pressure bonding method using no solvent is also possible and is not particularly limited.

The treatment amount of the above coating resin is generally 0.1 to 3 with respect to the carrier core material in view of the film forming property and durability of the coating material.
0% by weight (preferably 0.5 to 20% by weight) is desirable.

The method of measuring the characteristic values of the developer of the present invention will be described below. (1) Magnetic properties of carrier: The measuring device is BHU-60
A type magnetization measuring device (manufactured by Riken Seisakusho) is used. Specifically, about 1.0 g of the measurement sample is weighed and the inner diameter is 7 mmφ and the height is 1
It is packed in a 0 mm cell and set in the above device. In the measurement, the applied magnetic field is gradually added and changed up to 3,000 oersted. Next, the applied magnetic field is reduced to finally obtain the hysteresis curve of the sample on the recording paper. Than this,
Calculate saturation magnetization, remanent magnetization and coercive force. (2) Measurement of carrier particle size distribution: Microtrac particle size analyzer (Nikkiso Co., Ltd.) SRA type was used as the measuring device, and the measurement was performed in a range setting of 0.7 to 125 μm. (3) Toner particle size measurement: The particle size distribution can be measured by various methods, but in the present invention, it was measured using a Coulter counter.

That is, a Coulter counter TA-II type (manufactured by Coulter) is used as a measuring device, and an interface (manufactured by Nikkaki) and a CX-1 personal computer (manufactured by Canon) for outputting number average distribution and volume distribution are connected. Then, the electrolyte is 1
% NaCl aqueous solution is prepared. As a measuring method, a surfactant, preferably an alkylbenzene sulfonate, as a dispersant is added to 100 to 150 ml of the electrolytic aqueous solution in an amount of 0.1
Add ~ 5 ml, and then add 2 to 20 mg of the measurement sample.
The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and the Coulter Counter TA-II type was used to measure the volume and number of toners using a 100 μm aperture as an aperture. The volume distribution and number distribution of ˜40 μm were calculated. Then, according to the present invention, the weight-based weight average diameter (D
4) (the median value of each channel is set as a representative value for each channel), and the weight-based coarse powder amount (1
6.0 μm or more), and the number-based fine powder number (5.04 μm or less) determined from the number distribution was determined. (4) Hydrophobicity measurement: The methanol titration test is an experimental test for confirming the hydrophobicity of titanium oxide fine powder having a hydrophobized surface.

The "methanol titration test" defined in this specification for evaluating the hydrophobicity of the treated titanium oxide fine powder is performed as follows. Titanium oxide fine powder 0.2 g was placed in a 250 ml Erlenmeyer flask with 50 m of water.
Add to l. Methanol is titrated from the burette until the total amount of titanium oxide is wet. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed by suspending the total amount of fine titanium oxide powder in the liquid and the degree of hydrophobization is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached. (5) Transmittance measurement method: Sample 0.10 g Alkyd resin 13.20 (* 1) Melamine resin 3.30 (* 2) Thinner 3.50 (* 3) Glass media 50.00 * 1 ... Dainippon Ink Beckosol 1323-60-E
L * 2 ... Dainippon Ink Super Beckamine J-820-
60 * 3 ... Amilac thinner made by Kansai Paint

The above formulation was sampled in a 150 cc glass bottle,
Disperse for 1 hour with a paint conditioner manufactured by Red Devil Co., and after the dispersion is finished, apply to a PET film with a 2 mil doctor blade. This is heated at 120 ° C. for 10 minutes and baked to obtain U-BEST 5 manufactured by JASCO Corporation.
At 0, the transmittance is measured in the range of 320 to 800 nm and compared. (6) Method of measuring developer fluidity: In this experiment, the fluidity of the developer was measured as follows.

That is, the toner and the carrier are mixed at a toner concentration (0.5 to 20%) actually used, and the temperature is adjusted to 2
After leaving it in an environment of 3 ° C ± 2 ° C and a humidity of 60% ± 3% for 24 hours, measure it. The measuring method is based on JIS-Z 2502. Here, although the measuring device is shown in FIG. 1, a modified funnel as shown in FIG. 2 (a is a plan view and b is a cross-sectional view) is used.

[0100]

EXAMPLES Parts mean parts by weight.

Example 1 Polyester resin obtained by condensing 100 parts of propoxylated bisphenol and fumaric acid Phthalocyanine pigment 4 parts 4 parts of chromium complex salt of di-tert-butylsalicylic acid 4 parts were sufficiently premixed by a Henschel mixer and biaxial. The mixture was melt-kneaded with a type extruder, cooled, coarsely pulverized to about 1 to 2 mm using a hammer mill, and then finely pulverized by an air jet type fine pulverizer. Further, the finely pulverized product obtained was classified by a multi-division classifier to select 2 to 8 μm so as to obtain the particle size distribution of the present invention, to obtain colorant-containing resin particles.

The particles were mixed with hydrophilic anatase-type titanium oxide fine particles (particle size: 0.05 μm, BET120 m ² /
While the g) were mixed and stirred in a water-based, n-C ₄ H ₉ Si
Disperse (OCH ₃ ) ₃ in an aqueous system, add and mix so that the solid content is 20% by weight with respect to the titanium oxide fine particles while hydrolyzing, and mix so that the particles do not coalesce, dry and crush. The obtained hydrophobicity is 70% and the average particle size is 0.05μ.
Titanium oxide having a transmittance of 60% at m and 400 nm.
Cyan toner was prepared by mixing 5% with a Henschel mixer.

The weight average particle diameter of this cyan toner is 5.90 μm 4 μm or less 16.8 number% 5.04 μm or less 46.2 number% 8 μm or more 6.6% by volume 10.08 μm or more 1.0 volume % Met.

The carrier <A> shown in Table 1 was mixed with 7 parts of the above cyan toner so that the total amount was 100 parts to obtain a developer. This carrier <A> is a methyl methacrylate / butyl acrylate copolymer (copolymerization ratio 75/25)
About 1% by weight of a mixed resin of 80 parts and 20 parts of 1,1-dihydroperfluorooctyl methacrylate copolymer.
It was a coated carrier.

Using the above-mentioned developer, a commercially available Canon color copying machine CLC-500 (partially modified screw shape of developing device: developing sleeve having developing main pole 960 gauss 5
23 ° C / with built-in magnetic roller with pole structure)
Tested under a 60% temperature and humidity environment (developing condition V _cont = 3
50V, V _back = -130V). As a result, even after printing 10,000 sheets, the image density excellent in the fineness of the image is 1.5 to
A stable image was obtained at 1.6, and the developer concentration control was good and stable.

Further, when images were similarly printed at 23 ° C./5% and 30 ° C./80%, good results were obtained.

Example 2 As a carrier, instead of the carrier <A> of Example 1,
Methyl methacrylate / butyl acrylate = 75/2
5 parts of the copolymer of 5 to 6 parts of dimethylpolysiloxane
Image formation was performed in the same manner as in Example 1 except that the carrier <B> coated with the coating material in which the parts were mixed was used, and good results were obtained.

Example 3 As a carrier, instead of the carrier <A> of Example 1,
Methyl methacrylate / butyl acrylate = 75/2
Image formation was performed in the same manner as in Example 1 except that the carrier <C> coated with the coating material consisting of the copolymer of Example 5 was used, and after copying 10,000 sheets as compared with Examples 1 and 2. The image was slightly inferior in the fineness of the image quality, but good results were obtained.

Example 4 Toner using a quinacridone pigment in place of the phthalocyanine pigment of Example 1 as a toner. Weight average particle size 6.11 μm 4 μm or less 25.0% by number 5.04 μm or less 53.1% by number When 8 μm or more is 10.7% by volume, and when 10.08 μm or more is 1.4% by volume, and image formation was performed in the same manner as in Example 1 except that the carrier <B> in Table 1 was used, good results were obtained. Was obtained.

Example 5 Titanium oxide fine particles using 25% by weight of iso-C ₄ H ₉ -Si (OCH ₃ ) ₃ (hydrophobicity 65%, average particle size 0.05 μm, light transmittance 65% at 400 nm) A cyan toner was obtained in the same manner as in Example 1 except that was used, and image formation was performed in the same manner as in Example 1 in combination with the carrier <B> in Table 1, and good results were obtained.

Example 6 As a carrier, the carrier <D> in Table 1 was replaced with the carrier <A.
When an image was formed in the same manner as in Example 1 except that it was used in place of>, good results were obtained although the density slightly decreased after copying 10,000 sheets.

Comparative Example 1 As a carrier, the carrier <E> in Table 1 was replaced with the carrier <A.
When images were printed out in the same manner as in Example 1 except that the image density was unevenly generated, the image density after copying 10,000 sheets tended to decrease by about 0.1. It was

Comparative Example 2 Image formation was carried out in the same manner as in Example 1 except that the carrier <F> in Table 1 was used in place of the carrier <A>, but a good image was initially obtained, but 1 After printing 10,000 sheets, the image density decreased by about 0.2.

Comparative Example 3 When images were printed in the same manner as in Example 1 except that titanium oxide was not used, fog deteriorated at 23 ° C./60% and toner scattering occurred.

Comparative Example 4 Images were produced in the same manner as in Example 1 except that the carrier <G> in Table 1 was used in place of the carrier <A>, and the image quality was the same as that of Example 1 in terms of fineness. Although it was at a level, a carrier pull appeared and there was a white blank part on the image.

Comparative Example 5 An image was produced in the same manner as in Example 1 except that the carrier <H> in Table 1 was used instead of the carrier <A>, and the image quality was the same as that of Example 1 in terms of fineness. Although it was a level, there were many career pulls and there were many white parts on the image.

[0117]

[Table 1]

[0118]

[Table 2]

[0119]

The present invention is a two-component developer in which the chargeability and durability of a toner having a small particle diameter is improved. By using the two-component developer of the present invention, the number of copies can be increased. The stable charging is maintained, and a high-quality image can be obtained for a long time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an apparatus for measuring a fluidity of a developer.

FIG. 2 is an explanatory diagram of a funnel in the apparatus shown in FIG.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location G03G 9/10 351 (72) Inventor Makoto Kamibayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (3)

[Claims] 1. A two-component developer containing at least a toner having non-magnetic colorant-containing resin particles, an external additive, and a carrier, wherein (1) the toner has a weight average particle diameter of 3 to 7 μm, The toner having a particle diameter of 5.04 μm or less is contained in an amount of more than 40% by number, and the toner having a particle diameter of 4 μm or less is included in an amount of 10 to 70% by number, and 8 μm.
2 to 20% by volume of the toner having the above particle size is contained,
6% by volume or less of a toner having a particle size of 10.08 μm or more is contained, and (2) the carrier has a weight average particle size of 15 to 45 μm, and 1 to 20% of carrier particles smaller than 22 μm. , Carrier particles smaller than 16 μm are 3% or less, carrier particles 62 μm or more are 2% to 15%, carrier particles 88 μm or more are 2% or less, and the saturation magnetization of the carrier to an applied magnetic field of 3000 Oersted is 50%. To 90 emu / g, remanent magnetization of 10 emu / g or less, coercive force of 40 oersted or less, and (3) fluidity of the developer is 25 to 55 (sec / 50 g). And a two-component developer. 2. The external additive has an average particle size of 0.01 to 0.
The two-component developer according to claim 1, which is a titanium oxide fine particle having a thickness of 2 μm, a hydrophobicity of 20 to 98%, and a light transmittance at 400 nm of 40% or more. 3. In the carrier, one side of each rectangular parallelepiped (or cube) when the rectangular parallelepiped whose carrier shape circumscribes the carrier is assumed to be a>b> c or a> b = c or a = b> When a, b, and c are defined so that c or a = b = c, the average of b / a is 0.7 to 1.0 and the average of c / a is 0.6 to 1.0. The two-component developer according to claim 1 or 2, having a shape.