JPH02151877A - Magnetic toner and developing process - Google Patents

Abstract

PURPOSE:To obtain superior picture images under any environmental conditions by using a magnetic toner consisting at least of a binder resin and a magnetic body having specified compd. or a mixture of specified compd. adsorbed thereto, wherein a particle size of the magnetic body is specified. CONSTITUTION:The magnetic toner consists primarily of a binder resin and a magnetic body having a compd. expressed by the formula I or a mixture of the compds. adsorbed thereto. In the formula I, X is =CH2 or =C=O; R is an alkyl or alkenyl group which may contain a 6-24C OH group as substitu ent; n is a real number >=1; m is a real number >=0, and (m+n) is <=30; Further, the magnetic toner contains >=12 % (basing on the number of particles) magnetic toner particles having <=5 mum particles size, >=12% (basing on the number of particles) magnetic toner particles having 8-12.7 mum particle size, and <= 2.0 vol.% magnetic toner particles having >=16 mum particle size, wherein a volume average particle size of the magnetic toner is regulated to 4-10 mum. Thus, a magnetic toner capable of maintaining a stable electric charge under any low humidity environmental conditions is obtd., and picture images having stable reproducibility for fine lines and high resolving power without being influenced by temp. and humidity is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner for developing electrostatic latent images in electrophotography, electrostatic recording, etc., and a developing method thereof.

[Prior Art] Conventionally, two-component toners using a carrier and one-component toners containing a magnetic component are known as dry toners used in electrophotography and the like.

- component magnetic toner has the advantage that the developing device can be simplified,
It has been widely used because it is easy to maintain.

Generally, the following method is used to produce magnetic toner.

The magnetic material, binder resin, charge control agent, etc. are mixed uniformly using a mixer such as a Pall mill or Henschel mixer, and then melted and kneaded using a kneader such as a roll mill, extruder, or kneader to thoroughly incorporate each component. disperse. Thereafter, it is finely pulverized using a jet mill or the like, and then classified using an air classifier or the like to obtain a magnetic toner.

In addition, in order to improve the dispersion of the magnetic material in the binder resin,
Methods have been proposed in which the surface of a magnetic material is treated with various substances for the purpose of increasing the compatibility of the magnetic material with an organic material.

For example, JP-A-53-137148 discloses fatty acids and their derivatives, JP-A-53-81125 discloses polymeric materials, and JP-A-54-127329 discloses silane cuff pulling agents. JP-A-55-28018 discloses a titanium coupling agent. These materials are excellent in improving compatibility.

However, in a magnetic toner, a magnetic substance is exposed to some extent on the toner surface and discharges excessively charged charges, thereby playing a role in adjusting the amount of charge to an appropriate level. Therefore, when a magnetic material treated as described above is used, the philicity of the surface of the magnetic material is lost, the polarization increases, and the release of charge is inhibited, and the toner becomes overcharged and scatters on the image. Roughness may occur. In addition, the reflection force on the developing sleeve becomes strong, which may cause a decrease in density or cause unevenness in the sleeve coat. This phenomenon becomes more noticeable in low humidity environments or in high-speed machines, and it is inevitable that image defects will occur.

On the other hand, various magnetic materials are manufactured in order to obtain the desired magnetic properties, electrical properties, and powder properties, but some of them do not release enough charge, and compared to the above example, There are many magnetic materials that cause image defects, albeit to a lesser extent.

In addition, as a method for improving the dispersion of magnetic materials, JP-A-58
-1257413 Publication, JP-A-59-126544
Publication No. 1987-125747, Japanese Patent Publication No. 1983-125747
Publication No. 3-125748, JP 59-1257411
Publication No. 1, JP-A-59-125750, JP-A-8
No. 1-59349 discloses surfactants. These materials are excellent in improving compatibility, have stable charging properties even under low humidity, and give good images. Although it is moisture resistant in the sense that it does not undergo irreversible changes under high humidity conditions, it tends to release more charge and often causes a decrease in concentration.

On the other hand, in recent years, as image forming apparatuses such as electrophotographic copying machines have become widespread, their uses have expanded to a wide variety of uses, and demands on their image quality have become stricter. When copying images such as general documents and books, it is required to reproduce extremely fine details and fidelity, even down to the minute characters, without being crushed or cut off. In particular, when the latent image on the photoreceptor of an image forming apparatus is a line image of 11001z or less, fine line reproducibility is generally poor, and the line image clarity is still not sufficient. Furthermore, in recent image forming devices such as electrophotographic printers that use digital image signals, latent images are formed by dots with a constant potential gathered together.
Solid areas, halftone areas, and light areas are expressed by changing the dot density. However, if the toner particles do not adhere to the dots faithfully and the toner particles protrude from the dots, the gradation of the toner image that corresponds to the ratio of dot densities in the black and white areas of the digital latent image cannot be obtained. There are problems. Furthermore, when improving resolution by reducing dot size in order to improve image quality, the reproducibility of images made up of minute dots becomes even more difficult, resulting in poor resolution, poor gradation, and poor sharpness. This tends to result in images lacking in detail.

Further, although the image quality is good initially, the image quality may deteriorate as copying or printing continues. This phenomenon is thought to occur because, as copying or printing continues, only toner particles that are easy to develop are consumed first, and toner particles with poor developability accumulate and remain in the developing machine.

Up to now, several developers have been proposed for the purpose of improving image quality. Japanese Patent Publication No. 51-3244
The publication proposes a non-magnetic toner intended to improve image quality by regulating the particle size distribution. The toner mainly has a particle size of 8 to 12 μm, which is relatively coarse, and according to the studies of the present inventors, it is difficult to uniformly "glue" the latent image with this particle size. In addition, due to the characteristics that 5 μm or less is 30% by number or less and 20 μm or more is 5% by number or less, the particle size distribution is broad, which also tends to reduce uniformity. In order to form clear images using toner particles with a broad particle size distribution,
It is necessary to increase the apparent image density by thickly stacking the toner particles to fill the gaps between the toner particles, and there is also the problem that the amount of toner consumption required to achieve a predetermined image density increases.

Furthermore, in JP-A-54-72054, a non-magnetic toner having a sharper distribution than the former is proposed, but the particle size of medium weight particles is coarse, 8.5 to 11.0 μm, and There is still room for improvement as a toner in terms of resolution.

In JP-A No. 58-128437, the average particle size is 6 to
A non-magnetic toner has been proposed in which the particle size is 10 μm and the maximum number of particles is 5 to 8, but the number of particles of 5) z+n or smaller is as low as 15% or less, and images that lack sharpness tend to be formed. .

According to the studies conducted by the present inventors, it has been found that toner particles of 5p, m or less have the main function of clearly reproducing the outline of a latent image and densely applying the toner to the entire latent image. Ta. In particular, in an electrostatic latent image on a photoreceptor, lines of electric force are concentrated, so the electric field strength is higher at the edge portion than inside the image, and the sharpness of the image quality is determined by the quality of toner particles collected at this portion. According to studies conducted by the present inventors, it has been found that the amount of particles of 51 zm or less is effective in solving the problem of sharpness of image quality.

Also, U.S. Patent No. 4.299,! In specification No. 300,
A jumping development method using a developer having 10 to 50% by weight of magnetic toner of 20 to 35 μm has been proposed.

That is, in order to triboelectrically charge the magnetic toner, uniformly and thinly coat the toner layer on the sleeve, and further improve the environmental resistance of the developer, efforts have been made to find an appropriate toner particle size. However, considering the stricter requirements such as fine line reproducibility and resolution, this is not sufficient and further improvements are required. The inventors of the present invention have found that it is a problem that long spikes (silver toner particles) and disordered spikes of magnetic toner exist on the sleeve surface in the development area.

However, by reducing the particle size of the toner, the unit surface area per unit weight of the toner particles increases, so the amount of charge per toner particle increases. Therefore,
As the particle size of the magnetic toner is reduced, the amount of charge due to frictional electrification increases, and the magnetic toner gradually becomes overcharged.

Therefore, simply reducing the particle size of conventionally used magnetic toner tends to result in excessive charging, and when used in low humidity conditions, the amount of charging increases further, resulting in increased fogging, roughness, and scattering. , may cause a decrease in image density. Further, even if the toner coat is thin and uniform, and the magnetic toner has a small particle size, which is advantageous against sleeve coat unevenness, sleeve coat unevenness may occur under severe usage conditions. Further, in order to reduce the particle size, further improvement in the dispersibility of the magnetic material is required.

In view of the above, there is a need for a toner that provides good O2 images under any environment. In other words, what is needed is a magnetic toner that can disperse a magnetic material with desired characteristics in a binder resin, effectively adjust the amount of charge, and provide images with excellent latent image reproducibility and high resolution. .

[Problems to be Solved by the Invention] An object of the present invention is to provide a toner and a developing method that are not affected by environments such as temperature and humidity, and provide stable images especially under low humidity conditions.

Another object is to provide a toner and a developing method that achieve high image quality such as high resolution.

Another object of the present invention is to provide a toner and a developing method that have good dispersion of magnetic material in a resin, have excellent durability, and consistently produce fog-free images even after long-term continuous use. There is a particular thing.

Still another object is to provide a magnetic toner that does not impede the fixing properties and anti-offset properties of the binder resin.

[Means and effects for solving the problem] As a result of intensive research for the above purpose, the present inventor has developed a magnetic toner having a specific particle size distribution using a magnetic material with a specific compound adsorbed on the surface. It was discovered that the toner's chargeability was stabilized, the magnetic material was well dispersed in the resin, and the ring barrel stability and durability were excellent. The magnetic toner of the present invention is based on the above findings, and more specifically, the magnetic toner of the present invention is mainly composed of a binder resin and a magnetic material to which a compound represented by the following general formula (1) or a mixture thereof is adsorbed. This is a characteristic feature.

Furthermore, the present invention provides a magnetic toner having at least a binder resin and a magnetic material, which contains 12% or more by number of magnetic toner particles having a particle size of 5AIIl or less, and 8 to 12% by number.
．． Magnetic toner particles having a particle size of 7 pm are contained in an amount of 33% or less by number, magnetic toner particles having a particle size of 16 μm or more are contained in an amount of 2.0% by volume or less, and the volume average particle size of the magnetic toner is 4 to 10 μm. It is characterized by the fact that

The present invention will be explained in more detail below. In the following description, "%" and "part" expressing quantitative ratios are based on weight unless otherwise specified.

In the magnetic toner of the present invention, a magnetic material on which a compound represented by general formula (1) is adsorbed is used.

These compounds consist of an alkyl group serving as a hydrophobic group, an ether bond serving as a parent group, an amino group, and a hydroxyl group. Specifically, the following compounds may be mentioned.

G12 H25NHCHHz CH20H...(2)C
1o H21CHCH2NHCH2CH20H・” (
3) H C,+! H23C0-NH-1,000GH2CH20)-
H...(7)G++H23GO-NH-G-0120
820 liters --H (8) In the above compound, the number of ethylene oxide added is an average value.

In general, many compounds are known to exhibit hydrophilic and hydrophobic properties, but when adsorbed to a magnetic material, many of them are unable to release an effective charge and become overcharged, or absorb moisture significantly, resulting in an excessive charge. This causes the release of , resulting in a significant lack of charging.

In the compound of the present invention, the ether bond, amino group, and hydroxyl group, which are parent groups, facilitate adsorption onto a magnetic material. It is also believed that these functional groups suppress the polarization of the surface of the magnetic material and supplement effective charge release.

On the other hand, since the hydrophobic alkyl group of the compound of the present invention spreads on the surface of the magnetic material, the compatibility with the binder resin etc. is improved,
It is believed that this improves the dispersibility of the magnetic material in the toner and also suppresses significant moisture absorption.

Magnetic toner containing magnetic substances that have adsorbed these compounds does not absorb a lot of moisture, but under high humidity conditions the release of charge increases and the magnetic toner may not be able to maintain good developability, resulting in poor charging. As a result, a decrease in image density may occur. However, by making the magnetic toner containing the magnetic material, which is a feature of the present invention, have the particle size distribution described below, the above drawbacks can be overcome and the objects of the present invention can be achieved. That is, by defining the magnetic toner in the particle size distribution of the present invention, the amount of charge is increased, and the friction with the triboelectric charge imparting member is increased, the charging ability of the magnetic toner is improved, and the effect of the magnetic material used in the present invention is enhanced. It is something that makes it noticeable. Further, since reducing the particle size of the magnetic toner tends to result in excessive charging, the magnetic material of the present invention plays a role in controlling the amount of charge of the magnetic toner. In other words, the magnetic material of the present invention is suitable for use in magnetic toner with small particle size.

One of the characteristics of the magnetic toner of the present invention is that magnetic toner particles having a particle size of 5 μm or less account for 12% or more by number. Conventionally, in the case of magnetic toner particles, it is difficult to control the amount of charge of magnetic toner particles of 5) zm or less, and they tend to be overcharged. For this reason, toner particles of 5 μm or less have a strong reflection force on the developing sleeve, etc., and stick to the sleeve surface, inhibiting the frictional charging of other particles, generating toner particles with insufficient charging, and causing roughness and density reduction. It was thought that it was necessary to proactively reduce the risk of cancer.

However, according to studies conducted by the present inventors, it has been found that magnetic toner particles of 5 μm or less are an essential component for forming high-quality images.

For example, using a magnetic toner with a particle size distribution ranging from 0.5μff1 to 30μm, the surface potential on the photoreceptor can be changed from a large development potential contrast where large numbers of toner particles are easily developed, to halftones, to very small A latent image was developed by changing the surface potential on the photoconductor to a small development potential contrast in which only toner particles of It was found that there were many magnetic toner particles with a particle size of 51 or less, and in particular, there were many magnetic toner particles with a particle size of 51 or less. In other words, when magnetic toner particles with a particle size of 5 pm or less, which is most suitable for development, are smoothly supplied to develop the latent image on the photoreceptor, the latent image is faithful to the latent image, does not protrude from the latent image, and is truly reproducible. An excellent image can be obtained.

The magnetic toner containing the magnetic material of the present invention has a diameter of 8 μm or less,
In particular, the charging of magnetic toner particles of 5 ILrn or less is controlled appropriately, and the above-mentioned effects are effectively exhibited.

Further, in the magnetic toner of the present invention, 8 to 12.7 p.
One of the characteristics is that the number of particles in the range m is 33% or less by number. As mentioned above, this is related to the necessity of the presence of magnetic toner particles with a particle size of 5 μm or less, and 5) im
Magnetic toner particles with the following particle sizes have the ability to cover the latent image closely and reproduce it faithfully, but the electric field strength at the edges around the latent image itself is higher than at the center, so The toner particles may be less adhered to the inside than the edges, and the image density may appear lighter. In particular, 5μ
Magnetic toner particles with a size of m or less have a strong tendency to do so.

However, the present inventors have found that by containing toner particles in the range of 8 to 12.7 pm in an amount of 33% by number or less, this problem can be solved and further clarity can be achieved. That is, toner particles with a particle size in the range of 8 to 12.7 μm are different from magnetic toner particles with a particle size of 5 μm or less.
A moderately controlled band? This is thought to be due to the fact that the toner particles are supplied to the inner side of the latent image where the electric field strength is lower than the edge part, and this compensates for the lack of adhesion of the inner toner particles to the edge part, resulting in uniform development and image formation. As a result, a sharp image with high density and excellent resolution and gradation is provided.

Furthermore, for particles with a particle size of 5 μm or less, 12 to 00
If the number % is □, the number % (N) and volume % (V
), it is also preferable that the magnetic toner of the present invention satisfies the following relationship: N/V=-0,04N+k (4.5≦≦Ei, 5; 12≦N≦eo). The magnetic toner of the present invention having a particle size distribution satisfying this range can achieve better developability.

While studying the state of particle size distribution of 5 μm or less, the present inventors found that there is a state of existence of fine powder that best achieves the objective, as shown by the above formula. That is, 1
For a certain value of N where 2≦N≦60, the fact that N/V is large means 5! This shows that it contains a wide range of particles of Il or less, and a small N/V means that particles of 5 μm or less are included.
It is understood that this indicates that the abundance of nearby particles is high and there are few particles with smaller particle sizes.If N is in the range of 12 to 60, the value of N/V is 2.1 to 60. 5.82 and further satisfies the above relational expression, better fine line reproducibility and high resolution can be achieved.

Further, it is preferable that the amount of magnetic toner particles having a particle size of 18 μm or more be 2.0% by volume or less, and as small as possible.

The magnetic toner of the present invention solves the problems of the magnetic material used in the present invention and can withstand the recent strict demands for high image quality.

The configuration of the present invention will be explained in more detail.

Magnetic toner particles with a particle size of 5g11 or less account for 12 of the total number of particles.
It is good that it is more than % by number, preferably 12-60 % by number. 12 magnetic toner particles with a particle size of 5 pm or less
When the number of particles is less than %, there are few magnetic toner particles effective for high image quality, and in particular, as the toner is used by continuing copying or printing, the effective magnetic toner particle component decreases, and as shown in the present invention, the effective magnetic toner particle component decreases. The particle size distribution of the magnetic toner becomes unbalanced, and the image quality gradually deteriorates.

If the content is 60% by number or more, magnetic toner particles tend to aggregate with each other, resulting in toner lumps larger than the original particle size, resulting in rough image quality, lowering resolution, or causing the edges of the latent image to In some cases, the difference in density between the area and the inside becomes large, resulting in an image that appears hollow.

Further, it is preferable that the number of particles in the range of 8 to 12.7 μm is 33% by number or less, preferably 1 to 334% by number. If it exceeds 33% by number, the image quality will deteriorate and more development than necessary, that is, too much toner will be applied.
This leads to an increase in I.ner consumption.

On the other hand, if it is less than 1% by number, it may become difficult to obtain high image density. In addition, magnetic particles with a particle size of 5IL11 or less
There is a relationship between the number% (N%) of the toner particle group and 9% by volume (7%), N/V=-0.04N+, which is 4.5
≦ indicates a positive number in the range of ≦6.5. Preferably 4.5≦
is ≦6.0. As shown earlier, 12≦N≦60
It is.

If k<4.5, 5. If the particle size is smaller than Jtm, the number of magnetic toner particles is small, and the image density, resolution, and sharpness tend to be poor. □The moderate presence of fine magnetic toner particles, which were conventionally considered unnecessary, achieves close packing of toner during development and contributes to the formation of uniform images without roughness. In particular, by uniformly filling in thin lines and image contours, visual sharpness is further enhanced. That is, when k<4'', 5, these properties tend to be inferior due to the lack of this particle size distribution component.

From another point of view, in terms of production, conditions such as classification will become stricter in order to satisfy the condition of k < 4.5, which will be disadvantageous in terms of yield and toner cost.゛Also, k
> 13.5, due to the presence of more fine powder than necessary,
As copying is continued repeatedly, the balance of particle size distribution may be lost, the degree of agglomeration of the toner may increase, or frictional charging may not be performed effectively, resulting in poor cleaning or fogging.

In addition, magnetic toner particles with a particle size of 18 μm or more are 2.0 μm or more.
It is preferably less than or equal to volume %, more preferably 1.0
It is not more than 0.5% by volume, more preferably not more than 0.5% by volume. If it is more than 2.0% by volume, not only will it be a hindrance to reproducing fine lines, but during transfer, coarse toner particles of 18 μm or more will protrude on the thin layer surface of toner particles developed on the photoreceptor. This makes the delicate state of close contact between the photoreceptor and the transfer paper via the toner layer irregular, causing fluctuations in transfer conditions and causing a defective transfer image.

Further, the magnetic l-toner of the present invention cannot sufficiently retain the charge of magnetic toner particles of +6 μm or more, resulting in charging failure and fogging in the background area and inverted area.

The volume average diameter of the magnetic toner is 4 to IO4+, m, preferably 4 to 9 μm, and this value cannot be considered in isolation from the above-mentioned components. If the volume average particle diameter is 4 Pm or less, in applications where the image area ratio is high, such as graphic images, the amount of toner on the transfer paper is small and the problem of low image density tends to occur. This is considered to be due to the same reason as the reason why the density inside the edge portion of the latent image decreases as described above. If the volume average particle diameter is 101" or more, the resolution is not good, and even if copying is good at the beginning, image quality is likely to deteriorate with continued use. Further, image density tends to decrease under high humidity conditions.

The magnetic toner of the present invention having a specific particle size distribution can faithfully reproduce down to the fine lines of the latent image formed on the photoconductor, and can reproduce halftone dots and digital dot latent images. It provides images with excellent gradation and resolution. Furthermore, it maintains high image quality even when copying or printing is continued, and even in the case of high-density images, it is possible to perform good development with less toner consumption than conventional magnetic toner, making it economical. In addition, the magnetic toner of the present invention has the advantage of downsizing the main body of a copying machine or printer.As described above, the magnetic toner of the present invention uses a magnetic material to which a specific substance is adsorbed and has a specific particle size distribution. It was discovered that the electrostatic chargeability is stabilized, and the material has excellent environmental stability and durability.

Further, since the magnetic toner of the present invention has good dispersion of the magnetic material, it has excellent durability and is also characterized by providing images with very little fog, which is preferable for reducing the toner particle size.

The amount of the compound of the present invention to be used depends on the binder resin, the magnetic material, the presence or absence of additives used as necessary, the adsorption method to the magnetic material,
It is determined by the toner manufacturing method and is not uniquely limited. The preferred usage amount is magnetic material 1
0601 to 5 parts (more preferably 0.1
~3 parts). If the amount used is less than 0.01 part, the effect of charge release will not be effective, and if it is more than 5 parts, the charge will be released excessively, resulting in poor charging under high humidity and a decrease in image density. There is a fear.

The amount of the magnetic substance of the present invention contained in the toner is 20 to 150 parts, preferably 40 parts, based on 100 parts of the resin component.
~120 copies.

In order to achieve the same object as the present invention, although the effect is smaller than that of the present invention, it is possible to consider means of increasing the magnetic substance content. In this case, the ratio of magnetic material increases, which has a negative effect on fixing properties and causes low-temperature offset. Another disadvantage is that the organic photoreceptor is easily damaged. Furthermore, the strong magnetic binding force from the toner carrier reduces developability, resulting in image defects such as reduced image density and roughness.
It has the disadvantage of causing deterioration in image quality.

On the other hand, in the magnetic toner of the present invention, charge is effectively discharged, the amount of charge is stable, and fog is extremely low, so that the content of magnetic material can be reduced. Therefore,
The influence of magnetic binding force is reduced, resulting in improved image quality such as high density, no tailing, good resolution, and no roughness.

Furthermore, in addition to good dispersibility, it is advantageous in fixing properties and low-temperature offset resistance, and can fully demonstrate the performance of the binder resin. Furthermore, since it does not excessively damage the organic photosensitive layer, etc., it is preferably used in models using organic photoreceptors, etc.

The magnetic toner of the present invention exhibits its effects more effectively as the toner particle size is made smaller for the following reason. For example, in the case of magnetic toner, reducing the particle size has drawbacks such as increased fog and image defects due to excessive charging.

In order to solve these drawbacks, measures have been taken to increase the magnetic material content, but this results in the above-mentioned disadvantages. Also, the smaller the toner particle size, the greater the defects, so
It is necessary to increase the magnetic substance content □, which also increases the adverse effects. However, in the magnetic toner of the present invention, the magnetic substance content can be reduced, so that the adverse effects can be suppressed. The magnetic toner of the present invention can be sufficiently effective when the average volume particle size is 10 pm or less, particularly 9 pm or less, and the smaller the particle size, the more effective the effect can be expected.

According to the findings of the present inventors, when the particle size is made smaller or the magnetic material content is reduced, the magnetic brushes on the toner carrier become shorter and denser (even if the toner coat layer becomes thinner, the developing ability decreases). High-precision development is performed and the latent image reproducibility is excellent, resulting in high image quality. The magnetic toner of the present invention can achieve both of these requirements at the same time, and therefore can provide even better image quality.

The particle size distribution of toner can be measured by various methods.
In the present invention, a Coulter counter was used.

In other words, the measuring device is Coulter counter TA.
- An interface (manufactured by Nikkaki) that outputs number distribution 9 volume distribution using type II (manufactured by Coulter) and CX-
1 A personal computer (manufactured by Canon) is connected, and a 1% NaCj) aqueous solution is prepared using primary sodium chloride as the electrolyte. As a measurement method, the electrolytic aqueous solution 100~
A surfactant, preferably an alkylbenzene sulfonate (0.1 to 5 ml), is added as a dispersant to 150-ml, and 2 to 20 mg of a measurement sample is added thereto. The electrolytic solution in which the sample was suspended was dispersed for about 1 to 3 minutes using an ultrasonic disperser, and then dispersed using the Coulter Counter TA-II model, using a 100JL aperture as an aperture, to disperse the sample in an amount of 2 to 40 g based on the number of meters. The particle size distribution of the particles was measured and the values according to the invention were determined therefrom.

As the binder resin used in the toner of the present invention, the following toner binder resins can be used when a heated pressure roller fixing device having an oil coating device is used.

For example, monopolymers of styrene and its substituted products such as polystyrene, poly p-chlorostyrene, and polyvinyltornidi; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, and styrene-vinylnaphthalene copolymers. , styrene-acrylic acid ester copolymer, styrene-methacrylic acid triester copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-
Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile- Styrenic copolymers such as indene copolymers; excess vinyl chloride, laenol resin, naturally modified phenol resin, □Yaren resin-modified maleic acid resin, acrylic resin, methacrylic resin □Polyvinyl acetate, silicone resin, polymer □ Polyester resin, polyurethane, polyamide □ resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumaron indene resin, stone thread resin, etc. can be used.

In the heating and pressure roller fixing method, which does not apply much oil, a part of the toner image on the toner image support member is transferred to the roller.The so-called offset phenomenon and the adhesion of the toner to the toner image support member are important issues. be. Since toners that are fixed with less thermal energy tend to be easily blocked or quenched during storage or in a developing device, these problems must also be taken into consideration. The physical properties of the binder resin in the toner are the most important factor in these phenomena, but according to research by the present inventors, reducing the content of magnetic material in the toner improves the toner image support during fixing. Although the adhesion of the L-ner to the member is improved, the inherent properties of the binder resin are more likely to appear, offset is more likely to occur, and blocking or caking is also more likely to occur. Therefore, when using the heated pressure roller fixing method in which little oil is applied in the present invention, the selection of the binder resin is more important. Preferred binding materials include crosslinked styrenic copolymers or crosslinked polyesters.

Examples of comonomers for the styrene monomer of the styrenic copolymer include acrylic acid, butyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, and acrylic acid. Monocarboxylic acids having double bonds such as phenyl, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. or substituted products thereof; for example, maleic acid, Dicarboxylic acids with double bonds such as butyl maleate, methyl maleate, dimethyl maleate, etc. and substituted products thereof; for example, vinyl chloride, vinyl acetate,
Vinyl esters such as vinyl benzoate; ethylene olefins such as ethylene, propylene, butylene; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone; vinyl methyl ether, vinyl ethyl ether, Vinyl monomers such as vinyl ethers such as vinyl isobutyl ether may be used alone or in combination of two or more.

As the crosslinking agent, compounds having two or more polymerizable double bonds are mainly used, such as aromatic divinyl compounds such as EVA, divinylbenzene, and divinylnaphthalene; for example, ethylene glycol diacrylate, ethylene glycol Dimethacrylate, 1,3-butanediol dimethacrylate, etc.
Divinyl compounds such as carboxylic acid ester, divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and compounds having three or more vinyl groups are used alone or as a mixture.

In addition, when using a pressure fixing method, it is possible to use a binder resin for pressure fixing toner, such as polyethylene,
Polypropylene, polymethylene polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene
butadiene copolymer, styrene-isoprene copolymer,
Examples include linear saturated polyester and paraffin.

The magnetic materials contained in the magnetic toner of the present invention include iron oxides such as magnetite, maghematite, and ferrite, and iron oxides including other metal oxides; Fe, Go, and Ni.
or these metals and Aj), G
o, Gu, Pb, Mμ, Ni, Sn, Zn
, Sb, Be.

Bi, Cd, Ga, Mn, Se, Ti, W
, alloys with metals such as V, and mixtures thereof.

These ferromagnetic materials have an average particle size of about 0.1 to 24+ m, and a magnetic property with a coercive force of 20 to +5 when 10 KOe is applied.
00e Saturation magnetization 50-200emu/μ, residual magnetization 2~
2° emu/g is preferable.

Further, in the magnetic toner of the present invention, it is preferable that a charge control agent be added internally or externally to the toner. - Since the magnetic toner of Rikiki's invention stabilizes charging, there is a wide range of charge control agents to choose from.

Known positive charge control agents can be used in the present invention, such as nigrosine and its modified products with fatty acid metal salts, quaternary ammonium salts, diorganotin oxides, diorganotin borates, etc. alone or in combination. Can be used in combination. Among these, nigrosine type and quaternary ammonium salts are particularly preferably used.

(Left below) In addition, a monopolymer of the monomer represented by the general formula or a copolymer with a polymerizable monomer such as styrene, acrylic ester, or methacrylic ester as described above may be used as a positive charge control agent. In this case, it also functions as (part or all of) a binder resin.

On the other hand, known negative charge control agents can be used in the present invention, such as carboxylic acid derivatives and metal salts thereof,
Alkoxylates, organometallic complexes, chelate compounds, etc. can be used alone or in combination of two or more. Among these, acetylacetone metal complexes, salicylic acid metal complexes, and monoazo metal complexes are particularly preferably used.

Further, it is preferable to add fine silica powder to the magnetic toner of the present invention. A magnetic toner having a particle size distribution characteristic of the present invention has a larger specific surface area than conventional toners. When magnetic toner particles are brought into contact with the surface of a cylindrical conductive sleeve that has a magnetic field generating means inside for triboelectrification, the number of times the toner particle surface contacts the sleeve increases compared to conventional magnetic toner, and the toner particles Particle wear and sleeve surface contamination are more likely to occur. When the magnetic toner according to the present invention is combined with fine silica powder, wear is significantly reduced due to the presence of the fine silica powder between the toner particles and the sleeve surface. As a result, the life of the magnetic toner and the sleeve can be extended, and stable charging properties can also be maintained, making it possible to obtain a developer having a magnetic toner that is better for long-term use. moreover,
Magnetic toner particles having a particle size of 5#Lm or less, which play a major role in the present invention, exhibit more effectiveness in the presence of fine silica powder and can stably provide high-quality images.

As the silica fine powder, both silica fine powder produced by a dry method and a wet method can be used, but from the viewpoint of filming resistance and durability, it is preferable to use a silica fine powder produced by a dry method.

The dry method referred to here is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halide compound.For example, a method that utilizes the thermal/decomposition oxidation reaction of silicon tetrachloride gas in oxygen/hydrogen. The basic reaction formula is as follows.

5iCI! j + 2 H2+' 02→S 02 +
4 HCR Also, in this production process, for example, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halide compounds such as aluminum chloride or titanium chloride together with a silicon halide compound. Yes, it also includes them.

On the other hand, various conventionally known methods can be applied to produce the silica fine powder used in the present invention by a wet method.

For example, the general reaction formula for the decomposition of sodium silicate with an acid is shown below.

Na2O・XSiO2+HC1) +H20+SiO2
・nH2O+NaCjl! Other methods include decomposition of sodium silicate with ammonia salts or alkali salts, a method of generating alkaline earth metal silicate from sodium silicate and then decomposing it with acid to produce silicic acid, and a method of converting sodium silicate solution into ion exchange resin. There are methods such as using silicic acid, and using natural silicic acid or silicate.

The silica fine powder referred to herein can be any of anhydrous silicon dioxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate.

Among the above silica fine powders, the specific surface area due to nitrogen adsorption measured by the BET method is 30I12/g or more (especially 50 to 4
00 m2/g) gives good results. Silica fine powder 0.0 per 100 parts by weight of magnetic toner
It is good to use 1 to 8 parts by weight, preferably 0.1 to 5 parts by weight.

Further, when the magnetic toner of the present invention is positively chargeable,
As fine silica powder added to prevent toner wear and staining of the surface of the sli nib, rather than being negatively charged,
It is preferable to use positively charged silica fine powder because charging stability is not impaired.

As a method for obtaining positively chargeable silica fine powder, the above-mentioned untreated fine silica powder is added with at least one nitrogen atom in the side chain.
There is a method of treatment with a silicone oil having more than one organo group, a method of treatment with a nitrogen-containing silane coupling agent, or a method of treatment with both.

In the present invention, positively charged silica refers to silica that has a positive tripo charge relative to the iron powder carrier when measured by a plow-off method.

As the silicone oil having a nitrogen atom in the side chain used in the treatment of silica fine powder, a silicone oil having at least a partial structure represented by the following formula can be used.

Sl-〇- and/or -81-〇 (wherein R] represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, R2 represents an alkylene group or a phenylene group, and R3 and R4 represent hydrogen or an alkyl group , or an aryl group, and R5 represents a nitrogen-containing heterocyclic group) The above alkyl group, aryl group, alkylene group, or phenylene group may have an organo group having a nitrogen atom, or may impair chargeability. It may have a substituent such as halogen to the extent that it is not present.

Furthermore, the nitrogen-containing silane coupling agent used in the present invention is
It generally has a structure shown by the following formula.

Rm-3i-Y.

(R represents an alkoxy group or a halogen, Y represents an amino group or an organo group having at least one nitrogen atom, m and n are integers of 1 to 3, and m+n=4
It is. ) Examples of the organo group having at least one nitrogen atom include an amino group having an organic group as a substituent, a nitrogen-containing heterocyclic group, or a group having a nitrogen-containing heterocyclic group. Examples of the nitrogen-containing heterocyclic group include unsaturated heterocyclic groups and saturated heterocyclic groups, and known ones can be used. Examples of the unsaturated heterocyclic group include the following.

Examples of the saturated heterocyclic group include the following.

The heterocyclic group used in the present invention is preferably a five-membered ring or a six-membered ring in consideration of stability.

Examples of such treatment agents include aminopropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminepropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane. , monobutylaminopropyltrimethoxysilane, dioctylaminopropyltrimethoxysilane, dibutylaminopropyldimethoxysilane.

Dibutylaminopropyl monomethoxysilane Dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamine.

There are trimethoxysilyl-γ-propylbenzylamine, etc. Furthermore, as the nitrogen-containing heterocycle, those having the above-mentioned structure can be used. Examples of such compounds include trimethoxysilyl-γ-propylpiperidine, trimethoxysilyl- γ-propyl morpoline, trimethoxysilyl-γ-
Examples include propylimidazole.

The application amount of these treated positively charged silica fine powders is
0.01 per 100 parts by weight of positively charged fibrous toner
The effect is exhibited when the amount is 8 parts by weight, particularly preferably 0.
When added in an amount of 1 to 5 parts by weight, it exhibits positive chargeability with excellent stability. Regarding the preferred form of riveting, it is from 0.1 to 100 parts by weight of positively charged magnetic toner.
It is preferable that 3 parts by weight of the treated silica fine powder be attached to the surface of the toner particles. Note that the untreated fine silica powder described above can also be used in the same amount.

In addition, the silica fine powder used in the present invention may be treated with a silane coupling agent, a treatment agent such as silicone oil, an organosilicon compound for the purpose of hydrophobization, or a combination of various treatment agents, if necessary. It may be treated with the above-mentioned treatment agent that reacts with or physically adsorbs the silica fine powder.

Examples of such treatment agents include hexamethyldisilazane, trimethylsilyl, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane,
Allyl phenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate , vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyljethoxysilane,
Hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule, one each for the unit located at the end. S of
Examples include dimethylpolysiloxane containing a hydroxyl group bonded to i.

The silicone oil is generally represented by the following formula.

Preferred silicone oils have a viscosity of approximately 5 to 5000 centistokes at 25°C, such as methyl silicone oil.

Preferred are dimethyl silicone oil, phenylmethyl silicone oil, chlorphenylmethyl silicone oil, alkyl-modified silicone oil, fatty acid-modified silicone oil, polyoxyalkylene-modified silicone oil, and the like. These may be used alone or in a mixture of two or more.

Further, in the present invention, it is preferable to add fine powders of fluorine-containing polymers, such as polytetrafluoroethylene, polyvinylidene fluoride, etc., and fine powders of tetrafluoroethylene-vinylidene fluoride copolymers. Particularly preferred is polyvinylidene fluoride fine powder from the viewpoint of fluidity and polishability. The amount added to the toner is 0.
01 to 2.0% by weight, particularly 0.02 to 1.0% by weight are preferred.

In particular, in magnetic toners that combine fine silica powder with the above-mentioned fine powders, for reasons that are not clear, the state of the silica adhered to the toner is stabilized, and for example, the adhered silica is released from the toner, causing the toner to become The effect on wear and sleeve staining does not decrease, and
It is possible to further increase charging stability.

The magnetic toner of the present invention may contain additives, if necessary. Other additives include lubricants, such as zinc stearate, or abrasives, such as cerium oxide or silicon carbide, or flow agents, such as aluminum oxide, and anti-caking agents.

Lie during hot roll fixing: 0.5 to 5% by weight of a waxy substance such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, Sasol wax, paraffin wax, etc. for the purpose of improving moldability. It may be added to magnetic toner to some extent.

In the present invention, methods for adsorbing the compound used in the present invention onto the magnetic material include the following methods.

1) A method in which each component of the toner is added when mixing and adsorbed to the surface of a magnetic material during mixing and kneading.

However, with this method, the effect may be reduced or excessive moisture absorption may occur due to penetration into the binder resin or excessive exposure of the parent wood group.

There is also a possibility that the adsorption will not be carried out effectively on the surface of the magnetic material.

Therefore, in order to efficiently adsorb the material to the magnetic material and effectively achieve the object of the present invention, it is preferable to adsorb the material to the magnetic material in advance, and the following method is available.

2) A dry method in which the compound used in the present invention is added to a magnetic material, and then mixed and adsorbed using a Henschel mixer or a fret mill.

3) A wet method in which the compound used in the present invention and the magnetic material are dispersed and adsorbed in water or an organic solvent, followed by filtration and drying.

A dry method is a simple method, but a wet method is better in order to achieve more uniform adsorption on the surface of a magnetic material, and a method using water as a solvent is the best method due to safety and ease of production. This is the preferred method.

In manufacturing the toner according to the present invention, the toner constituent materials as described above are sufficiently mixed using a ball mill or other mixer, then thoroughly kneaded using a heat kneader such as a hot roll kneader or an extruder, and then cooled and solidified. Preferably, the toner is obtained by mechanical pulverization or classification; another method is to obtain the toner by dispersing the constituent materials in a binder resin solution and then spray drying; Polymerization toner production method in which a monomer is mixed with a predetermined material to form an emulsified suspension and then polymerized to obtain a toner; or in so-called microcapsule toners consisting of a core material and a shell material, the core material or shell material , or a method in which a predetermined material is contained in both of them; and the like can be applied.

Furthermore, the magnetic toner according to the present invention can be produced by sufficiently mixing desired additives with a mixer such as a Henschel mixer, if necessary.

The magnetic toner of the present invention can be produced by electrophotography, electrophotography, etc. by conventionally known means.
All of them can be used for one-component development for visualizing electrostatic images in electrostatic recording, electrostatic printing, etc.

The magnetic toner of the present invention is preferably applied to an image forming method in which a latent image is developed while flying the toner from a toner carrier such as a cylindrical sleeve to a latent image carrier such as a photoreceptor. That is, the magnetic toner is given a tripo charge mainly through contact with the sleeve surface, and is coated in a thin layer on the sleeve surface. The thickness of the thin layer of magnetic toner is formed to be thinner than the gap between the photoreceptor and the sleeve in the development area. When developing a latent image on the photoreceptor, it is preferable to apply an alternating electric field between the photoreceptor and the sleeve, and then cause the magnetic toner having a tripo charge to fly from the sleeve to the photoreceptor.

Examples of the alternating electric field include a pulsed electric field, an alternating current bias, or a combination of alternating current and direct current bias.

On the other hand, as a method for uniformly coating the magnetic toner onto the toner carrier (sleeve), the surface is sandblasted with amorphous particles to form a roughened surface with a specific unevenness. It is possible to provide an excellent developing device that can always maintain a good toner coating state over a long period of time, with uniformity and no unevenness on the surface of the toner carrier. The target surface has numerous fine incisions and protrusions arranged in random directions.

However, in a developing device using a toner carrier having such a specific surface condition, depending on the applied magnetic toner,
Components in the toner tend to adhere to the surface, causing so-called contamination of the surface of the toner carrier. As a result, the density of the initial image decreases, and if the contamination progresses due to durability, the toner carrier may be contaminated once per cycle of the toner carrier. White areas in the image occur.

This is because components in the toner adhere to the slopes of convex portions and concave portions on the surface of the toner carrier, resulting in poor banding of magnetic toner particles and a decrease in the amount of charge in the toner layer.

In general, the components in magnetic toner consist of materials such as a magnetic binder resin, a charge control agent, and a release agent.The materials are designed to prevent contamination of the surface of the toner carrier. The current situation is that the selection of options is restricted.

Furthermore, if the surface of the toner carrier is smooth or has a specific unevenness formed by a plurality of spherical trace depressions, no matter what kind of material the magnetic toner is applied to, the toner will not be applied to the surface. Components become difficult to adhere to, and contamination can be prevented or reduced over a long period of time.

However, in terms of the ability to uniformly coat a toner carrier with magnetic toner, a toner carrier having a surface with specific irregularities formed by spherical trace depressions is difficult to achieve because of the ability to uniformly coat a toner carrier with magnetic toner. Under certain circumstances, it is inferior to a toner carrier having an uneven surface with cuts or protrusions in random directions, but it is superior to a toner carrier having a completely smooth surface.On the other hand, the magnetic toner of the present invention By using this on a toner carrier having a surface with spherical trace depressions, it is possible to prevent the toner coating layer from becoming excessively thick, and even in a toner carrier with a smooth surface without toner coating unevenness, it can be used for a long period of time. Can be evenly coated with toner. Therefore, as a result, it is possible to obtain clear, high-quality images with high image density, excellent fine line reproducibility and gradation, and no fogging over a long period of time.

The present invention will be described in detail below, and the toner carrier will hereinafter be referred to as a sleeve.

When the sleeve of the present invention has a surface with an uneven surface formed by a plurality of spherical trace depressions, a blasting method using regular particles can be used to obtain the surface condition. As the regular particles, for example, various rigid spheres such as metals such as stainless steel, aluminum, steel, nickel, and brass, ceramics, plastics, and glass beads having a specific particle size can be used. By blasting the sleeve surface using regular particles having a specific particle size, it is possible to form a plurality of spherical trace depressions with approximately the same diameter R.

In the present invention, the diameter R of the plurality of spherical trace depressions on the sleeve surface is preferably 20 to 250 pm;
If it is less than 0 pm, it is not preferable because it increases contamination due to components in the magnetic toner. Therefore, the diameter of the regular particles used when blasting the sleeve surface is 20 to 250 μm.
The one is good. In addition, in the present invention, the pitch P of unevenness on the sleeve surface and the surface roughness d are determined by measuring the surface roughness of the sleeve using a micro surface roughness meter (manufactured by Teilani Hopson, Koita Institute, etc.). d is based on 31810 point average roughness (RZ) rJIS B 0801J.

In other words, the interval between the two straight lines, one parallel to the average line obtained by extracting the standard length from the cross-sectional curve and passing through the third peak from the highest, and the other passing through the bottom of the third valley from the deepest one, is calculated by micrometer. It is expressed in meters (interval ■),
Standard length l'=0.25m+s. Moreover, the pitch P is 0.0. Items with a height of I 71 or higher are counted as one mountain, and the standard length is 0.25 mm.
It is calculated as follows based on the number of mountains in the middle.

250 (L)/Number of peaks included in 250 (L) (g) In the present invention, the pitch P of the unevenness on the sleeve surface is between 2 and 250 (L).
100 JL is preferable, and if P is less than 21 L, it is not preferable because the sleeve contamination due to components in the magnetic toner increases. The surface roughness d of the unevenness on the sleeve surface is 0.
1 to 5 μm is preferable, and when d is 51 or more, in a method of developing by applying an alternating voltage between the sleeve and the latent image holder to cause the magnetic toner to fly from the sleeve side to the latent image surface, This is not preferable because the electric field tends to concentrate on the uneven portions and cause image disturbance.

In the present invention, fine line reproducibility was measured by the following method. In other words, an image of an original manuscript with thin lines accurately set to long 11 in width was copied under appropriate copying conditions as a sample for measurement, and a Luzex 450 particle analyzer was used as the measurement device to measure the line width using an indicator from the enlarged monitor image. Perform measurements. At this time, since the line width measurement position has irregularities in the width direction of the fine line image of the toner, the average line width of the irregularities is taken as the measurement point. From this, the value (%) of fine line reproducibility is calculated using the following formula.

In the original name of the present invention, the resolution was measured by the following method. In other words, it is a pattern consisting of five thin lines with equal line width and spacing, with a distance of 2.8°3.2.3.13.4.0.4 within 1 mm.
．． 5.5.0.5.8. e, 3.7.1 or 8.0
Create original images that look like they are in a book. Observe with a magnifying glass the image copied from the original document with these 10 types of line images under appropriate copying conditions, and calculate the resolution value by calculating the number of images (wood/mm) in which thin lines are clearly separated. do.

The larger this number, the higher the resolution.

[Examples] The present invention will be explained in more detail below with reference to Examples.
This is not intended to limit the invention in any way. All parts in the following formulations are parts by weight. Examples of manufacturing the magnetic material used in the present invention are shown below.

Production Example 1 Slurry concentration is 93.5 g/j in 10 aqueous solutions of compound (4) (1.4 g/i)! Add magnetic substance A (magnetic iron oxide) and stir for 1 hour.
Magnetic material B was obtained by heating and drying.

At this time, the amount of adsorption was 1.2 parts per 100 parts of the magnetic material.

Production Example 2 Magnetic material C was obtained in the same manner as Production Example 1, except that a 1.0 g/4 aqueous solution of compound (5) was used instead of compound (4).

The amount of magnetic material C adsorbed was 0.9 parts per 100 parts of the magnetic material.

Production Example 3 1.2 g/i of compound (lO) instead of compound (4)
A magnetic material was obtained in the same manner as in Production Example 1 except that the aqueous solution of ' was used.

The adsorbed amount of the magnetic material was 1.0 parts per 100 parts of the magnetic material.

Production Example 4 Magnetic material F was obtained in the same manner as in Production Example 1, except that magnetic material E (magnetic iron oxide) was used instead of magnetic material A.

The adsorption amount of magnetic material F was 1.2 parts per 100 parts of magnetic material.

Since the compound of the present invention is distributed into the solvent at a constant flow rate, the amount of adsorption is determined by the concentration of the original solution of the compound and the slurry concentration of the magnetic material.

In addition, when 6e is applied to 10 of magnetic material A, the magnetic property is coercive force 13
30 e, saturation magnetization of 83.7 parts mu/g, and residual magnetization of 12.5 parts mu/g. The average particle size is 0.15 μm.

The magnetic material E has a coercive force of 836 e and a saturation magnetization of 91, respectively.
．． 8 parts mu/g + residual magnetization E1.4 emu/g. The average particle size is 0.20 μm.

Example 1 After premixing the above materials in a Henschel mixer, 15
Kneaded with an extruder heated to 00G, cooled, coarsely pulverized with a cutter mill, pulverized with a fine pulverizer using a jet stream, and further classified using an air classifier to obtain particles with an average volume particle size of 8.11L. A classified powder was obtained. The particle size distribution is shown in Table 1. Positively charged hydrophobic colloidal silica (BET 200m2/g) 0.5 parts to 100 parts of this classified powder
A magnetic toner was obtained by thoroughly mixing the two parts with a Henschel mixer. The obtained magnetic toner was subjected to commercially available electrophotographic copying*(
Table '2 shows the results of copying 5000 sheets using product name NP1215, manufactured by Canon, roughening of the developing sleeve, diameter of the depression 53 to B2IL, pitch of unevenness 30, and surface roughness 2).

As is clear from Table 2, images with no fog and excellent fine line reproduction were obtained.

Similar results were also obtained at 15° C. and 10% RH at 132.5° C. and 85% RH.

The amount of charge of the toner on the toner carrier during the test was +5
~+8 nc/cm2.

In the present invention, the charge amount of the toner layer per unit area on the carrier was determined using the so-called attraction Faraday cage method. In this suction type Faraday cage method, the outer cylinder is pressed against the toner carrier to suck all the toner on a certain area on the carrier, and the toner is collected in a filter in the inner cylinder. The weight of the toner layer per unit area above can be calculated. At the same time, this method allows the amount of charge per unit area on the toner carrier to be determined by measuring the amount of charge accumulated in the inner cylinder which is electrostatically sealed from the outside.

Example 2 A toner was obtained in the same manner as in Example 1 except that magnetic substance C was used in place of magnetic substance B used in Example 1. However, hydrophobic colloidal silica (BET300m2/g) is 0.
．． Six parts were used. The particle size distribution of the classified powder is shown in Table 1, and the results of the same copying test as in Example 1 are shown in Table 2. As shown in Table 2, images with excellent original reproduction were obtained.

Also 15°C910%RH132,5°C985%RH
Similar results were obtained under the test.The amount of toner charge on the toner carrier during the test was +6 to +
It was 9 nG/cm2.

Example 3 A toner was obtained in the same manner using the materials of Example 1, except that 80 parts of magnetic material B was used in place of magnetic material B used in Example 1. However, 0.8 part of positively charged hydrophobic colloidal silica was used.

- The particle size distribution of the classified powder is shown in Table 1, and the results of the same copying test as in Example 1 are shown in Table 2.

As is clear from Table 2, images with high resolution were obtained.

The amount of charge of the toner on the toner carrier during the test was +7~
+9 nc/cm2.

Example 4 Using the above materials, classified powder was obtained in the same manner as in Example 1:
0.8 part of hydrophobic colloidal silica (BET 300 layer 2/g) was added externally. Table 1 shows the particle size distribution of the classified powder.

This toner is applied to a commercially available electrophotographic copying machine (product name NP-75).
Table 2 shows the results of a 5,000-sheet copying test using 50, manufactured by Canon.

As shown in Table 2, high quality images with excellent reproducibility were obtained. Also 15℃, 10%RH 132.5℃.

Similar results were obtained under 85% RH. The charge amount of the toner on the toner carrier during the test was -5 to -10 nG.
/cm2.

Comparative Example 1 A toner was obtained in the same manner as in Example 1, except that 70 parts of magnetic material A was used instead of magnetic material B used in Example 1.

Table 1 shows the particle size distribution of the classified powder, and Table 2 shows the results of a copying test conducted in the same manner as in Example 1. As is clear from Table 2, good results were obtained. However, 15℃
, under 10% RH, a good image was obtained initially, but as the number of copies was increased, the image became slightly rough, fog increased, and the density decreased (1.35→1.15).

At this time, the amount of charge of the toner on the toner carrier is +IB
It was nC/cm2.

Comparative Example 2 A toner was obtained in the same manner as in Example 1, except that 100 parts of magnetic material A was used instead of magnetic material B used in Example 1.

Table 1 shows the particle size distribution of the classified powder, and Table 2 shows the results of a copying test conducted in the same manner as in Example 1.

As shown in Table 2, good results were observed, but trailing and roughness were slightly more common than in Example 1. Further, although there was no problem in practical use, the fixing performance was somewhat poor, and there were many scratches on the photosensitive drum, which began to appear on the images after 5,000 copies were printed.

Comparative Example 3 A toner was obtained in the same manner as in Example 1, except that 50 parts of magnetic material B was used.

Table 1 shows the particle size distribution of the classified powder, and Table 2 shows the results of a copying test conducted in the same manner as in Example 1.

There were no problems with image density or fog, but image quality such as resolution and fine line reproducibility was poor.

Furthermore, the image density is low at 32.5°C and 185%RH.
Especially in the early stages, it is low 1.07 to 1.15, and solid black is 1.
．． It was as low as 00.

The initial charge amount of the toner on the toner carrier is +3
It was nc/cm2.

Comparative Example 4 A toner was obtained in the same manner as in Example 1, except that 80 parts of magnetic substance A was used instead of magnetic substance B.

Table 1 shows the particle size distribution of the classified powder, and Table 2 shows the results of a copying test conducted in the same manner as in Example 1.

There was no problem with image density, but there was a lot of fogging, solid black areas were rough, and image quality such as resolution and fine line reproducibility was poor.
Toner consumption was also high. In addition, sleeve coat unevenness was observed in the non-image area.

(The following is a blank space) [Effects of the Invention] The present invention is a magnetic toner that has been subjected to the above-mentioned magnetic material surface treatment and has a specific particle size distribution, and therefore exhibits the following excellent effects. ζ.

■ Maintains stable charge even in low humidity environments.

■ Unaffected by temperature and humidity, it provides stable images with fine line reproducibility and high resolution.

■ Excellent durability, maintaining the initial high image quality even after long-term use.

■ Provides high image density with low consumption.

■ The magnetic material is well dispersed in the binder resin, has excellent durability, and consistently provides fog-free images.

■ Allows the binder resin to fully demonstrate its performance without adversely affecting fixing properties and anti-offset properties.

Claims (1)

[Scope of Claims] (1) Magnetic toner particles having a particle size of 5 μm or less in a magnetic toner having at least a binder resin and a magnetic material adsorbing a compound represented by the following general formula (1) or a mixture thereof. Contains 12% or more by number, 8 to 12.7
Magnetic toner particles having a particle size of μm are contained in an amount of 33% or less by number, magnetic toner particles having a particle size of 16 μm or more are contained in an amount of not more than 2% by volume, and the volume average particle size of the magnetic toner is 4 to 10 μm. A magnetic toner characterized by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) [In the above general formula, X is >CH_2 or >C=OR
represents an alkyl group or alkenyl group which may have a hydroxyl group having 6 to 24 carbon atoms as a substituent; n and m represent real numbers such that n≧1, m≧0 and n+m≦30. (2) An electrostatic image carrier that holds an electrostatic image on its surface and a toner carrier that carries the magnetic toner according to claim 1 on its surface are arranged with a certain gap in a developing section, and the magnetic toner is A developing method characterized in that the toner is regulated to a thickness thinner than the gap on a toner carrier and conveyed to a developing section, and the toner is developed in the developing section while applying an alternating electric field to the toner. (3) The developing method according to claim 2, wherein the toner carrier has a smooth surface. (4) The developing method according to claim 2, wherein the toner carrier has a surface having irregularities formed by a plurality of spherical trace depressions by blasting with regular shaped particles. (5) The surface of the toner carrier has a spherical trace depression with a diameter R=
5. The developing method according to claim 4, wherein the pitch of the unevenness is 20 to 250 μm, the pitch of the unevenness is 2 to 100 μm, and the surface roughness d is 0.1 to 5 μm.