JPH0264555A - magnetic toner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic toner for developing electrostatic latent images formed in electrophotography, electrostatic printing, electrostatic recording, and the like.

[Prior Art] Conventionally, as a developing method using a component magnetic toner, a developing method using a conductive magnetic toner disclosed in U.S. Pat. No. 3,909,258 and the like is known.
It is also widely used.

However, in such a developing method, the toner needs to be electrically conductive, and the electrically conductive toner uses an electric field to transfer the toner image on the latent image carrier to the final image supporting member (for example, plain paper). However, it was difficult to transfer the images (although the reason for this is not fully understood).

The present applicant has previously proposed a new developing method that solves the problems of the conventional developing method using one-component magnetic toner (for example, Japanese Patent Application Laid-Open No. 55-18858 and Japanese Patent Application Laid-Open No.
5-18859). In this method, insulating magnetic toner is uniformly applied onto a cylindrical toner carrier having a magnet inside, and the toner is developed by facing the latent image carrier without contacting it.

As a method of forming a toner layer on a toner carrier, there is a method of using a coating blade at the outlet of a toner container.
For example, in the device shown in FIG. 1, a blade la made of a magnetic material is provided at a position facing one magnetic pole N1 of a fixed magnet 4 housed in a toner carrier 2, and the magnetic force lines between the magnetic pole and the magnetic blade are The thickness of the toner layer is regulated by making spikes of toner stand along the blade and cutting the spikes with the edge portion of the tip of the blade, thereby making use of magnetic force (see, for example, Japanese Patent Application Laid-Open No. 54-43037).

During development, a low-frequency alternating voltage is applied between the toner carrier and the base conductor of the latent image holder to cause the toner to reciprocate between the toner carrier and the latent image holder, thereby eliminating ground force blur. In addition, it has excellent gradation reproduction and can perform good development without thinning at the edges of the image. In this developing method, since the toner is an insulator, electrostatic transfer is easy.

In FIG. 1, 7 is a developing device containing toner lO;
is a latent image holding body (hereinafter referred to as a photoconductor or photoconductor drum) such as a photoconductor drum in electrophotography and an insulating drum in electrostatic recording.

In such a developing method, the problem is to uniformly coat the magnetic toner onto the toner carrier;
It is extremely important to prevent or reduce contamination of the surface of the toner carrier by components in the i-type toner. However, the problem and the problem (2) are in conflict with each other, and it is difficult to solve both issues simultaneously.

In other words, in problem 1, as a method for uniformly coating a toner carrier with magnetic toner, the present applicant has developed a method that can stably form a uniform toner coat layer on a toner carrier for a long period of time in practice. We proposed a developing device (
JP-A-57-88455), which is shown in FIG. 1 as a toner carrier.

By sandblasting the surface with irregularly shaped particles,
By using a rough surface with a specific unevenness, the surface of the toner carrier is uniform and even.
This is an excellent developing device that can always maintain a good toner coating condition over a long period of time. The target surface is one in which numerous minute incisions or protrusions are formed in random directions over the entire surface of the stainless steel cylindrical toner carrier.

However, in a developing device using a toner carrier having such a specific surface condition, depending on the applied magnetic toner, the toner or components in the toner may easily adhere to the surface, resulting in so-called contamination on the surface of the toner carrier. As a result, when the density of the initial image decreases and its contamination progresses due to durability, there is a tendency for omissions within the image to occur during the rotation period of the toner carrier. this is,
Components in the toner adhere to the convex slopes and concave areas on the surface of the toner carrier, resulting in poor charging of magnetic toner particles.
This is caused by a decrease in the amount of charge on the toner layer.

In general, components in a magnetic toner include materials such as a binder resin, a magnetic material, a charge control agent, and a release agent. Although materials are designed to prevent contamination of the surface of the toner carrier, the selection of materials is currently extremely limited.

Regarding issue (2), as a method to prevent or reduce contamination of the magnetic toner carrier, it is easy to infer that this is the opposite trend to issue (2), but in fact, it is better to make the surface of the toner carrier smoother. It was clear that However, in this method, the volume average particle size of the magnetic toner is 1
It has been experimentally found that when it is 21 or more, the toner coat tends to become non-uniform, causing unevenness in the visible image and making it impossible to obtain a good image. When the phenomenon causing this toner coating unevenness was observed in detail by idle rotation of the developing device, the following was discovered.

Although the cause is unknown at the beginning of idle rotation, if the surface of the toner carrier is smooth, the toner coating layer becomes excessively thick. The toner protrudes to the side (section A in Figure 2), as shown in the enlarged cross-sectional view in Figure 4.
A toner pool 10a is generated in the A section. When the toner pool reaches a certain limit, the transfer force of the sleeve 2 is transferred onto the sleeve, causing uneven coating as shown in 3a. If there are toner lumps like 3a in the toner layer 3 coated like -, these will appear unevenly on the image. The unevenness of the image includes dense unevenness, uneven fogging, etc. It was found that the shape of the toner application unevenness 3a includes a rectangular spot pattern, a wavy spot pattern, a wavy pattern, etc.

As described above, with the conventional developing method, it is extremely difficult to solve both the problem and the problem (2) at the same time.

Furthermore, these tendencies become more noticeable in machines where the humidity is low or the circumferential speed of the toner carrier is high.

[Problems to be Solved by the Invention] The purpose of the present invention is to provide a solution for uniformly coating a toner carrier with magnetic toner on a toner carrier in the above-mentioned developing method under any environment and even in high-speed machines for a long period of time. The purpose of the present invention is to provide a magnetic toner with a high quality.

A further object of the present invention is to provide a magnetic toner that has high image density, excellent fine line reproducibility and gradation, and can provide clear, high-quality images without fog over a long period of time.

[Means and effects for solving the problems] The present invention provides a magnetic toner having at least a bound shelf fat and a magnetic powder.
The present invention relates to a magnetic toner characterized in that the volume average particle diameter is within the range of 7 to 10 μm, and the number distribution of magnetic toner particles and the amount of triboelectric charge satisfy the following general formula (1).

Q (μc/g) = O, 1 (μc/g) A + K (μc/
g) ``(l) Conventionally, magnetic toner has a toner carrier that has a smooth surface or a specific unevenness formed by a plurality of spherical trace depressions, making it difficult for toner components to adhere to the surface. Since contamination can be prevented or reduced over a long period of time, there is no reduction in the charging ability of the toner carrier, and the magnetic toner can be charged efficiently at all times.

However, the above-mentioned toner carrier does not have the ability to uniformly coat the toner carrier with magnetic toner, and the toner carrier has an uneven surface with numerous fine incisions or protrusions in random directions by sandblasting with irregularly shaped particles. Slightly inferior under certain conditions compared to carriers0
For example, when magnetic toner with a high charging ability is applied to a high-speed machine under low humidity, the toner carrier has a large charging ability, so the amount of charge on the magnetic toner increases, and the mirroring force on the toner carrier increases. As the size increases, the cohesive force of the magnetic toner also increases, causing aggregates of magnetic toner to form on the toner carrier, causing toner coating unevenness.

On the other hand, in the magnetic toner of the present invention, any toner carrier can be used as long as it has a volume average particle size within the range of 7 to 10 gm, has a specific particle size distribution, and has an appropriate charge amount, and can be used to form a toner coat layer. This prevents the toner from becoming excessively thick, so that toner coating can be uniformly applied over a long period of time without causing toner coating unevenness.

As a result, it is possible to obtain clear, high-quality images with high image density, excellent fine line reproducibility and gradation, and no fog over a long period of time.

The present invention will be specifically explained below. Further, the toner carrier is hereinafter referred to as a sleeve.

The sleeve carrying the magnetic toner in the present invention preferably has a surface with an uneven surface formed by a plurality of spherical trace depressions, and a blasting method using regular particles can be used to obtain this surface condition. As the regular particles, for example, various rigid spheres made of metal such as stainless steel, aluminum, steel, nickel, and brass, or various rigid spheres such as ceramic, plastic, glass beads, etc., 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 H.

In addition, the diameter R of the plurality of spherical trace depressions on the sleeve surface is 2
The diameter R is particularly preferably 0 to 250 μm, and the diameter R of 20 μm or less depends on the components in the magnetic toner. Contamination tends to increase, and conversely, if the diameter R is 250 gm or more, the toner coating on the sleeve tends to be less uniform. Therefore, it is preferable that the diameter of the regular particles used when blasting the sleeve surface be 20 to 250 mm.In addition, in the present invention, the pitch P of the irregularities on the sleeve surface and the surface roughness d are such that the sleeve surface has a microscopic surface. Measured using a roughness meter (manufactured by Taylor Hopson, Koita Institute, etc.)
Surface roughness d is JIS 10 point average roughness (RZ) rJ
It is based on IS B Q801J.

In other words, as shown in Figure 3, there are two lines: one that is parallel to the average line of the section of the cross-sectional curve with the reference length extracted, and that passes through the third peak from the highest point, and one that passes through the bottom of the third valley from the deepest point. , the distance between two straight lines is expressed in micrometers (the final square), and the reference length fL = 0.25 m1.

In addition, the pitch P is based on a standard length of 0.25, when the height of the convex part is 0.1 g or more relative to the concave parts on both sides, which is counted as one mountain.
It is calculated as follows based on the number of peaks in mm.

[250 (Le)] / [Number of mountains included in 250 (JL) (end) 1 Pitch P of unevenness on the surface of the sleeve is 2 to 10
0 g is preferable; if P is less than 2 JL, sleeve contamination by components in the magnetic toner tends to increase; on the other hand, if P exceeds 100 μ, the uniformity of the toner coat on the sleeve decreases. There is a tendency. In addition, the surface roughness d of the unevenness on the sleeve surface is preferably 0.1 to 5 knits.
If d exceeds 5 μ layer, if the developing method is to apply an alternating voltage between the sleeve and the latent image holder and cause the magnetic toner to fly from the sleeve side to the latent image surface, The electric field tends to concentrate and cause image disturbance, and conversely, if d is less than 0.1 g, the uniformity of the toner coat on the sleeve tends to decrease.

For example, the most preferable sleeve for use in the magnetic toner of the present invention is one in which the surface of the stainless steel sleeve is blast-treated with glass beads having a diameter of 53 to 62 μm and 80% or more of the shaped particles.

In the magnetic toner according to the present invention, the volume average particle diameter is 7.
The coefficient of variation of the number distribution within the range of ~10H is 25~45 (
One feature is that the number is preferably 26 to 44). As mentioned above, the most preferable sleeve for the magnetic toner according to the present invention (hereinafter referred to as the present sleeve 2-1) has a specific uneven surface with a plurality of spherical grooves. In terms of the ability to uniformly coat the sleeve, the experimental results were slightly inferior under certain environments compared to the sleeve (hereinafter referred to as Comparative Sleeve 2-2) that smoothes the uneven surface by sandblasting with irregularly shaped particles. It was done. It applies magnetic toner with a volume average particle diameter of 12 corners or more to a developing device having the main sleeve 2-1 and the comparative sleeve 2-2 under a specific environment of a temperature of 15°C or less and a humidity of 10% or less. When the sleeve is rotated idly, the weight M/S of the toner layer per unit area on the sleeve becomes
-1 has 1.8 w 2.3 mg/cm2, and comparative sleeve 2-2 has 0.8 to 1.5 layers g/c2. Sleeve 2-1 has a thicker toner coat and is more empty. It has been confirmed that if the rotation is continued for a long time, uneven toner coating may occur in the sleeve 2-1 as shown in FIG. 2.

However, according to the studies of the present inventors, although the reason is not necessarily clear, when similar experiments were conducted using magnetic toner having the particle size distribution of the present invention, this sleeve 2-1
Even if the M/S on the sleeve is 0.5 to 1.5 mg/
It was found that the toner coat thickness could be kept low in C layer 2, and as a result, no sleeve coat unevenness occurred even after idling for a long time, and the toner coat thickness was reduced over a long period of time to ensure uniformity of the toner coat. We discovered a fact that is extremely effective in

However, even for magnetic toner with a volume average diameter in the range of 7 to 10 μ■ and a coefficient of variation of the number distribution of 25 to 45, if the circumferential speed of the sleeve is increased (220 mm/sea or more) and the idle rotation time is prolonged under low humidity, It has been found that some toner forms aggregates of magnetic toner on the sleeve and causes uneven sleeve coating. It has also been found that the faster the circumferential speed of the sleeve, the shorter the time it takes to generate magnetic toner aggregates. The amount of electric charge of the magnetic toner before sleeve coating unevenness of this magnetic toner increased with the idle rotation time, and was considerably larger than that of the magnetic toner that did not cause sleeve coating unevenness. Furthermore, when these magnetic toners were mixed with an iron powder carrier and the charge amount was measured, the former showed a larger value than the latter.

It has been found that when a magnetic toner with such a large amount of triboelectric charge is applied to a high-speed machine, uneven sleeve coating occurs under low humidity conditions for the reasons mentioned above.

When the volume average particle diameter is within the range of 7 to 10 μm and the coefficient of variation of the number distribution is 25 or less, the M/S on the sleeve tends to increase and sleeve coating unevenness tends to occur, although the reason is not clear. . Further, when the particle size is 45 or more, the particle size distribution becomes wide, so that the charging properties of the toner particles become non-uniform, which tends to cause a decrease in density, and the state of spikes on the sleeve is disturbed, causing roughness and a decrease in resolution.

The coefficient of variation of the number distribution can be adjusted in the classification process, but it is 25 to 4
Within the range of 5, if the amount of charge of the magnetic toner on the iron powder carrier is within the range of 4≦ and ≦12 according to the general formula (1), uniform sleeve coating can be achieved and a good image can be obtained.

In the case of k≧12, in other words, if the amount of charge is large and the sleeve rotates at high speed (circumferential speed of 220sv/+ec or more) in low humidity, excessive charging will occur and uneven sleeve coating will occur. It becomes easier to do.

On the other hand, when ≦4, that is, when the amount of charge is small,
The amount of charge that cannot be obtained due to insufficient developability, low density, and poor images can be controlled by selecting and using the magnetic charge control agent.

In addition, the magnetic toner having the particle size distribution and charge amount of the present invention has thin, short, and uniform spikes on the developing sleeve without any disturbance, so it has excellent fine line reproducibility and resolution and can produce clear images without fog. give.

Furthermore, since the magnetic toner of the present invention adheres uniformly to the transfer material, it has excellent gradation properties and can provide high image density while reducing consumption.

By the way, when manufacturing magnetic toner, bottles are used.

When pulverized using a mechanical pulverizer that uses a disc, rotor, and liner, or gently pulverized by lowering the air pressure with a jet mill, magnetic toner tends to become highly charged and the sleeve coat may become uneven. There is.

Therefore, when producing magnetic toner, it is important to carry out jet mill pulverization with appropriate air pressure. In addition, the smooth developing sleeve used for magnetic toner, as described above, has excellent ability to impart frictional electrification, so it can effectively apply frictional electrification to the magnetic toner, and the amount of charge of the magnetic toner on the sleeve is stable. High image density and high image quality can always be maintained.

Conventionally, after the electrostatic latent image shown in FIG. 4 is developed into a toner image, a transfer device 22 applies an electric charge of opposite polarity to the toner to the back side of a transfer material 24 that is in close contact with the toner image, and the image is separated by electrostatic attraction. The toner image is transferred onto a transfer material 24. Immediately after the transfer process is completed, an AC corona or the like is applied to the back surface of the transfer material 24 using the molecular a device W23 to eliminate the charge on the transfer material 24 and also separate the image carrier 21. In this image forming method, the toner particle size is reduced. In this case, the adhesion between the image carrier and the transfer material becomes strong, which is disadvantageous for retransfer in the separation step 6. However, the magnetic toner of the present invention is preferably used in the above-mentioned image forming method because the amount of charge is suitably controlled in the developing step.

In other words, when the amount of charge of the magnetic toner is small, the adhesion to the transfer material is poor and re-transfer to the latent image carrier occurs during separation, causing defects such as white spots on the image. If this is large, uneven transfer to the transfer material may cause transfer failure and re-transfer upon separation.

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 a Coulter counter〒A
- An interface (manufactured by Nikkaki) that outputs the number distribution and two volume distributions using Type II (manufactured by Coulter) and CX-
1 A personal computer (manufactured by Canon) is connected, and a 1% NaCR aqueous solution is prepared using first grade sodium chloride as the electrolyte. As a measurement method, the electrolytic aqueous solution 100-1
0.1 to 5 p of a surfactant, preferably an alkylbenzene sulfonate, as a dispersant is added to 50 mjJ, and 2 to 2 hg of a measurement sample is added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment using an ultrasonic disperser for about 1 to 3 minutes, and then dispersed using the Coulter Counter TA-II type using a 100p aperture as the aperture, and dispersing the sample in a 2 to 40mm aperture based on the number of samples. The particle size distribution of the particles was measured and the values according to the present invention were determined therefrom.

As the binder resin used in the magnetic toner of the present invention, the following toner binder resins can be used when a heating and 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 polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers , styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl Styrenic copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenol Resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin,
xylene resin, polyvinyl butyral, terpene resin,
Coumarone indene resin, petroleum-based resin, etc. can be used.

In the heating and pressure roller fixing method that does not apply much oil, the so-called offset phenomenon, in which a part of the toner image on the toner image support member is transferred to the roller, and the adhesion of the toner to the toner image support member are important issues. be. Toners that require less heat energy to fix tend to be prone to blocking or caking during storage or during development, so these issues must also be taken into account. According to research by the present inventors, reducing the content of magnetic material in the toner improves the adhesion of the toner to the toner image supporting member during fixing; Offset is more likely to occur, and blocking or caking is also more likely to occur. Therefore, in the present invention, when using a heated pressure roller fixing method in which little oil is applied, 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, methyl 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, methacrinitrile, acrylamide, etc. or substituted products thereof; e.g., eva, maleic acid, Dicarboxylic acids with double bonds such as butyl maleate, methyl maleate, dimethyl maleate, etc. and substituted products thereof; e.g., vinyl chloride, vinyl acetate,
Vinyl esters such as vinyl benzoate; ethylenic olefins such as ethylene, propylene, butylene, etc.; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, etc.; vinyl methyl ether, vinyl ethyl ether, etc. Vinyl monomers such as vinyl ethers such as , vinyl isobutyl ether, etc. 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 divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate,
Carboxylic acid esters having two double bonds such as ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and three or more vinyl Compounds having groups can be 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,
Examples include polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, and paraffin.

In addition, in order to control the amount of charge in the magnetic toner of the present invention, it is preferable to use a charge control agent by adding it to the toner particles (internal addition) or mixing it with the toner particles (external addition). Depending on the agent, it is possible to control the amount of charge optimally depending on the developing system, and in particular, in the present invention, it is possible to further stabilize the balance between particle size distribution and charge. Examples of positive charge control agents include modified products with nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroporate; dibutyltin oxide and dioctyltin. Diorganotin oxide such as oxide, dicyclohexyltin oxide: Diorganotin porate such as dibutyltin porate, dioctyltin porate, dicyclohexyltin porate, etc. can be used alone or in combination of two or more types. Among these, charge control agents such as nigrosine and quaternary ammonium salts are particularly preferably used.

Further, the general formula [wherein R1 represents H or CH3, R2 and R3
is a substituted or unsubstituted alkyl group (preferably C1"
Cs); or a copolymer with a polymerizable heptamer such as styrene, acrylic ester, or methacrylic ester as described above as a positive charge control agent. In this case, these charge control agents also act as (in whole or in part) a binder resin.

It is preferable to use the above-mentioned charge control agent (one that does not act as a binder resin) in the form of fine particles. In this case, the number average particle size of the charge control agent is specifically:
4B or less (more preferably 3 B or less) is preferable.

When internally added to the toner, such a charge control agent is added in an amount of 0.1 to 20 parts by weight (or even 0.1 to 20 parts by weight) per 100 parts by weight of the binder resin.
．． 2 to 10 parts by weight) is preferably used.

In the magnetic toner of the present invention, various additives may be added internally or externally as necessary.As the colorant, conventionally known dyes and pigments can be used, and usually, dyes and pigments that are known in the art can be used. Other additives that may be used in an amount of 0.5 to 20 parts by weight per 100 parts by weight of the adhesive resin include, for example, lubricants such as zinc stearate; abrasives such as cerium oxide and silicon carbide; colloidal silica, Fluidity-imparting agents or anti-caking agents such as fermented aluminum; conductivity-imparting agents such as carbon black and tin oxide.

In addition, in order to improve mold releasability during hot roll fixing, waxy substances such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, Sasol wax, paraffin wax, etc. are added to the binder resin. It is also one of the preferred embodiments of the present invention to add about .5 to 5 wt% to the magnetic toner.

Furthermore, the magnetic toner according to the present invention may also serve as a colorant, but it contains a magnetic material.

The magnetic materials contained in the magnetic toner of the present invention include iron oxides such as magnetite, γ-iron oxide, ferrite, and iron-rich ferrite; metals such as iron, cobalt, and nickel, or these metals and aluminum, cobalt, Examples include alloys with metals such as copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

It is desirable that these ferromagnetic materials have an average particle size of 0.1-1 μm, preferably 0.1-0.5 μm, and the amount of these ferromagnetic materials contained in the magnetic toner is based on 100 parts by weight of the resin component. The amount is 60 to 120 parts by weight, preferably 65 to 110 parts by weight per 100 parts by weight of the resin component.

To prepare the magnetic toner for developing electrostatic images according to the present invention, magnetic powder, vinyl or non-vinyl thermoplastic resin, pigment or dye as a coloring agent, charge control agent, and other additives are used as necessary. etc. are sufficiently mixed using a mixer such as a ball mill, and then melted, kneaded, and kneaded using a heat kneader such as a heated roll, niegu, or extruder to make the resins compatible with each other. The magnetic toner according to the present invention can be obtained by dispersing or dissolving it, cooling and solidifying it, and then pulverizing and strictly classifying it.

Further, fine silica powder may be added internally or externally to the magnetic toner of the present invention, but it is more preferable to mix it externally.

The magnetic toner that is a feature of the present invention may have poor fluidity, and depending on the developing device, may not be able to fully exhibit its triboelectric charging ability.

By externally adding and mixing fine silica powder to the magnetic toner according to the present invention, fluidity is improved, opportunities for contact with the triboelectric charging member are increased, and more of the magnetic toner's triboelectric charging ability is effectively utilized. It can exhibit good developability in any developing device.

Furthermore, a magnetic toner having a particle size distribution as a feature 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 When the magnetic toner according to the present invention is combined with fine silica powder, the wear of the particles 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 can be extended, and stable charging properties can also be maintained, making it possible to obtain a magnetic toner that is more excellent in long-term use.

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

5iCj? i + 2 H2+ 02→5i02+ 4
HCRAlso, in this manufacturing process, 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, and these can also be used. include.

Commercially available fine silica powder produced by vapor phase oxidation of a silicon halide compound used in the present invention includes, for example, those commercially available under the following trade names.

AEROSIL 130 (Japan Aerosil Co., Ltd.) Ca-0-8iL (CABOTOCo, Inc.) Wacker HDK N 20 (WACKER
-CHE) IIE 0M80 Co.) x50 TE100 0X80 0X170 0O to 84 S-7 S-5 H-5 20E D-CFine 5ilica (Dow Corning Co., Ltd.) Fransol (Fran+i1 Co.) On the other hand, one silica fine powder used in the present invention Various conventionally known methods can be used to produce the body using a wet method.

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

Na2O・XSiO2+HCj) +H20→S+02
・nH2O+NaC! ! Other methods include decomposition of sodium silicate with ammonia salts or alkali salts, generation of alkaline earth metal silicate from sodium silicate and then decomposition with acid to produce silicic acid, and method of decomposing sodium silicate solution with 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.

Commercially available fine silicic acid powders synthesized by a wet method include those sold under the following trade names, for example.

Carplex Neep Seal Tokushir, Fine Zelvita Shiruton, Silnex Star Shiru Meji Rusai
Lloyd Shionogi Pharmaceutical Nippon Silica Tokuyama Soda Taki Hizusawa Chemical Kamishima Chemical Ehime Pharmaceutical Fuji Davison Chemical Formerly -5il (Hiseal) Pittsburgh Plate Glass, C
.

(Pittsburgh Plate Glass) Durosil (Do90 Seal) Old Torasil (Ultra Seal) Fills
toff-Gegelschaft Marquard
Manos i I Hardman and Ho1den Chemische Fabrik Hoesch
K-G (Hiemische Fabrik Herras)
Sit-9tone Storr
er Rubber Co, (Stoner Rubber) Nalco Nalco Chew, Go, (Nalco Chemical) Quso Philadelphia Quartz Co.

(Philadelphia Quartz) Imsil 1nerals Go to 111i1oj3.

(Illinois Mineral) Calcium 5ilikat (Calcium Silicate) Chemische Fabrik Hoe
sch, K-G Calsil Fiillstoff-Gesellschaft
Marquart Fortafil Imperia
l Chemical Industries, Lt.
d.

(Imperial Chemical Industries) Former crocal (Microcal) Joseph Crogfiel+ & 5ons L
td.

(Joseph Crossfield Samp) AndVuikagil (Purkagil) Farbenfabriken Bryer, A, -
G.

(Falpen Fabricen Bayer) Tufknit
(Tough ---/T) 11urham Chem
icals, Ltd.

(Durham Chemicals) Silmos Shiroishi Kogyo Starex Kamishima Kagaku Fricosil Takihiro Among the above silica fine powders, the specific surface area due to nitrogen adsorption measured by the BET method is 30 m2/g or more (especially 50 to 40 m2/g).
0+s2/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.

In addition, in the case of the positively charged magnetic toner according to the present invention, it is better to use positively charged silica fine powder than to use negatively charged silica fine powder as the silica fine powder added to prevent wear of the toner. This is preferable since it does not impair charging stability.

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 blow-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.

(In the formula, R1 represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, R2 represents an alkylene group or a phenylene group, R3 and R4 represent hydrogen, an alkyl group, or an aryl group, and R5 represents a nitrogen-containing heterocycle. Note that the above alkyl, group, aryl group, alkylene group, and phenylene group may have an organo group having a nitrogen atom, or a substituent such as halogen may be added to the extent that the chargeability is not impaired. You may have one.

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

R@-3i-Yn (R represents an alkoxy group or halogen, Y represents an amine group or an organo group having at least one nitrogen atom, m and n are integers of 1 to 3, and m+n
=4. ) 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, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane. Silane, 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-propylmorpholine, trimethoxysilyl-γ
- Propylimidazole, etc.

The application amount of these treated positively charged silica fine powders is
0.01 to 100 parts by weight of positively charged magnetic toner
The effect is exhibited when the amount is 8 parts by weight, particularly preferably 0.1
A preferred form of addition is 0.1 to 100 parts by weight of the positively charged magnetic toner, which exhibits positive chargeability with excellent stability when added in an amount of 5 parts by weight.
It is preferable that 3 parts by weight of the treated silica fine powder be attached to the surface of the toner particles; however, the aforementioned untreated silica fine powder can also be used in the same amount.

Furthermore, the silica fine powder used in the present invention may be treated with a silane coupling agent or a treatment agent such as an organosilicon compound for the purpose of hydrophobization, if necessary, to react with or physically adsorb to the silica fine powder. Treated with the above-mentioned processing agent. Examples of such treatment agents include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane,
Trimethylethoxysilane, dimethyldichlorosilane.

Methyltrichlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-
Chlorethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyljethoxysilane, hexa Methyldisiloxane, l, 3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and having from 2 to 12 siloxane units per molecule, with one unit per molecule located at the end. Examples include dimethylpolysiloxane containing a hydroxyl group bonded to Si.

These can be used alone or in a mixture of two or more.

Further, in the magnetic toner according to the present invention, a fine powder of a fluorine-containing polymer may be added internally or externally. Examples of the fine powder of a fluorine-containing polymer include polytetrafluoroethylene, polyvinylidene fluoride, etc. and fine powder of tetrafluoroethylene-vinylidene fluoride copolymer, etc., and polyvinylidene fluoride fine powder is particularly preferred in terms of fluidity and polishability.

The amount added to the toner is 0. O2N2. Owt%, especially 0.02-1. Q wt% is better.

Particularly, in magnetic toners in which fine silica powder is mixed with the above-mentioned fine powders and externally added, the state of existence of silica attached to the toner is stabilized, for example, the attached silica is released from the toner, although the reason is not clear. L, the effect on toner abrasion and sleeve staining does not decrease, and charging stability can be further increased.

An example of a specific apparatus that can be used to carry out the developing step in the present invention is shown in FIG. 5, but this is not intended to limit the present invention in any way.

In the developing device shown in FIG.
Using a stainless steel sleeve (SuSt 304), the magnetic poles of magnet 4 inside the sleeve are: N+ = 850 Gauss, N2 = 500 Gauss, S+ = 850 Gauss,
The S2 depth is 500 Gauss, the blade la is made of iron, which is a magnetic material, and the gap between the blade la and the sleeve 2-1 is 2.
501L, ) The toner lO is the magnetic toner according to the present invention, and the bias power supply 11 is one in which DC is superimposed on AC, Vpp = 1200V, f = 800
(Hz) and rJC=+100W. Another example is one in which the shortest distance between the sleeve 2 and the latent image holder 9 is set to 300μ.

In the present invention, the charge amount of the toner layer per unit area on the carrier and the weight of the toner layer were determined using the so-called suction type Faraday cage method. This suction type Faraday cage method presses the outer cylinder against the toner carrier to suck all the toner on a certain area on the carrier, collects it in a filter in the inner cylinder, and uses the increased weight of the filter to absorb the toner carrier. The weight of the toner layer per unit area of t 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 M accumulated on the inner cylinder that is electrostatically shielded from the outside.

Further, a method for measuring the amount of charge of magnetic toner in the present invention will be explained in detail with reference to the drawings.

Figure 6 measures the amount of charge of magnetic toner? This is a close-up explanatory diagram. First, put about 1 g of a mixture of magnetic toner and iron powder carrier (200 to 30 G mesh) in a weight ratio of 1:9 into a metal measurement container 32 with a 400 mesh screen 33 at the bottom, and place the metal. Lid 34 made of
do. At this time, weigh the entire weight of the measuring container 32 W+
(g) Then, in the suction device 31 (at least the part in contact with the measurement container 32 is an insulator), suck it from the suction port 37 and adjust the air volume control valve 36 to adjust the pressure on the vacuum gauge to 250 m
Let mH+O. In this state, suction is performed sufficiently (for about 1 minute) to remove the toner. At this time, the potential of the electrometer 39 is set to V (volt). Here, 38 is a capacitor whose capacitance is C and F), and the weight of the entire measurement container after suction is measured as W2 (g).The amount of charge of this magnetic toner is calculated as shown below. Ru.

However, the measurement conditions are 23° C. and 80% RH. The carrier (iron powder) used for the measurement is 200 to 300 mesh, but in order to eliminate errors, the carrier is sufficiently suctioned with the suction device mentioned above, and the carrier that passes through the 400 mesh screen is removed before the magnetic toner is removed. Mix with.

Mixing time is approximately 30 seconds.

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but these are not intended to limit the present invention in any way. All parts in the following formulations are parts by weight.

Example 1 A cylindrical stainless steel sleeve (S
The surface of OS 304) was sprayed using glass beads with 80% or more diameter of 53 to 82 mm as regular particles, blowing nozzle diameter 7φ distance a 100 mm l air pressure 4 kg/
Blasting was performed under the conditions of cm2 and 2 minutes to form unevenness in which a plurality of spherical grooves had a diameter R of 53 to 82H. The pitch P of the unevenness on the surface of this sleeve was 33 tiles, and the surface roughness d was 2.0 l. This surface-treated sleeve was installed in a copying machine NP-5540.

On the other hand, the following magnetic toner was used.

After mixing the above ingredients well in a blender.

The mixture was kneaded using a twin-screw extruder set at 150°C.

The obtained kneaded material was cooled and coarsely pulverized with a cutter mill, and then 6 kg/
The powder was pulverized using an air pressure of cm2, and the resulting pulverized powder was classified using a fixed wall type wind classifier to produce a classification box. Furthermore, the obtained classification box was subjected to simultaneous classification and removal of ultrafine powder and coarse powder using a multi-division classification device that utilizes the Coanda effect (Nichisen Mining Co., Ltd.'s Elbow Jet Classifier). Toner A was obtained.

The coefficient of variation of the number distribution of this magnetic toner A was 33.5. The coefficient of variation is a value that indicates the degree of variation from the average value, and is a feature of the magnetic toner of the present invention, so by adjusting the classification conditions etc. and classifying more precisely, the desired value can be obtained. A magnetic toner having a particle size distribution could be obtained. The coefficient of variation is a measure of dispersion;
A smaller value means sharper, and a larger value means broader, but this is a scale that also includes variations depending on the grain size. Therefore, it is not enough to simply classify and remove fine powder and coarse powder; instead, the particle size distribution of the finely pulverized product is determined, and the classification conditions ( In the elbow jet, the toner of the present invention was obtained by adjusting the edge distance, differential pressure settings, etc., and carefully classifying the toner.

As mentioned above, the particle size distribution of the obtained magnetic toner was measured using a Coulter Counter Model TA-■ equipped with 7 perchers of 100 mm, and the amount of triboelectric charge against iron powder is shown in Table 1.

0.0% of positively charged hydrophobic dry silica (BET specific surface area 200s2/g) was added to 100 parts of the obtained black fine powder magnetic toner.
5 parts were added and mixed in a Henschel mixer.

Electrophotographic copying machine NP-55 equipped with the sleeve described above
Toner A was added to 40°C and an image reproduction test was carried out at 15°C.

5000 0 image output test conducted under 1O%RH environment
The results of repeated tests are shown in Table 2. As is clear from Table 2, at the initial stage, the weight M/S of the toner layer per unit area on the sleeve was 1, OB/Cm2. What is the charge jQ/S of the toner layer per unit area? , it shows a moderate value at 8 nc/c layer, and even after 5000 sheets of durability, M/S = 1. IB/cm2Q/S=8.5n
c/ca2, and the toner coating on the sleeve was also extremely uniform. In addition, the surface of the sleeve after being used for 5,000 sheets was observed with a scanning electron microscope after air cleaning, and it was found that no toner components were attached to the irregularities on the surface, and substantially no sleeve contamination occurred. Both the initial image and the 5,000-sheet durable image have high image density, no fog, and are clear, with resolution, fine line reproducibility, and halftone dot reproducibility 9.
It was a high quality image with excellent gradation.

Further, similarly good results were obtained in a durability test under an environment of 32.5° C. and 85% RH.

Examples 2-3 (4 parts of low molecular weight ethylene-propylene copolymer) Magnetic toner B having different particle size distributions as shown in Table 1 was prepared in the same manner as in Example 1 using the above materials.

C was prepared. 0.8 parts of positively charged hydrophobic dry silica (BE 150 m2/g) was added to 100 parts of these magnetic toners, mixed with a Henschel mixer, and evaluated in the same manner as in Example 1. As shown in Table 2, both the initial image and the image after 5,000 sheets of printing had high image density, no fog, and were clear and of high quality.There was also no sleeve contamination, and there was no toner coating unevenness on the sleeve. was also not recognized.

Example 4 A magnetic toner D having a particle size distribution as shown in Table 1 was prepared using the above materials in the same manner as in Example 1. Hydrophobic silica (BET 200 m2/g) was added to 100 parts of this magnetic toner.
The same evaluation as in Example 1 was carried out by adding 0.5 parts and mixing with a Henschel mixer.

The results were good, as is clear from Table 2.

Examples 5 to 6 Magnetic toner E having different particle size distributions as shown in Table 1 was prepared in the same manner as in Example 1 using the above materials.

F was prepared by rIR. Positively charged hydrophobic silica (BET 200 2/g) 0.8 to 100 parts of these magnetic toners
The same evaluation as in Example 1 was carried out by adding 1.0 parts and mixing with a Henschel mixer.

The results are shown in Table 2, and as is clear from this table, high quality images were obtained in good condition.

Example 7 A sleeve was surface-treated in the same manner as in Example 1, except that 1300 carbon random particles, which were amorphous particles, were used instead of the glass beads used in Example 1. Evaluations were conducted in the same manner as in Example 1, except that the sleeve described above was used instead of the sleeve used in Example 1. The results are shown in Table 2.

The initial image was clear with no fog, but
A slight decrease in image density was observed in the images after printing 000 images. Furthermore, when the sleeve was cleaned with air after the durability test and observed under a scanning electron microscope, it was found that toner components were deposited on the sleeve surface, indicating that the sleeve was contaminated.

Example 8 In Example 1, the sleeve surface was not blasted with regular particles, but was rubbed using fine powder of cerium oxide as an abrasive to give it a smooth, mirror-like finish. Evaluation was performed in the same manner as in Example 1 except that this sleeve was used in place of the sleeve used in Example 1. The results are shown in Table 2.

Although a clear image with high density and no fog was obtained, it was slightly inferior in gradation compared to Example 1.

Comparative Example 1 In the same manner as in Example 1, magnetic toner G having the average grain size and particle size distribution shown in Table 1 was prepared.

Magnetic toner G with the same external addition as in Example 1.

The same evaluation as in Example 1 was performed. The results are shown in Table 2.

When Toner G was used in this evaluation, the initial image was good, but during durability, some unevenness was observed in the toner coat on the sleeve, and image defects and unevenness were observed in the image area corresponding to that area. A type of fog was observed.

Comparative Example 2 A magnetic toner H having a volume average particle size and particle size distribution as shown in Table 1 was prepared in the same manner as in Example 2.

Magnetic toner H with the same external addition as in Example 2 was prepared in Example 1.
A similar evaluation was made. The results are shown in Table 2.

When Toner H was used in this evaluation, initial and 5000
Both of the images after the sheet durability test were unsatisfactory as the image density was low and the force of the adhesive was noticeable.

Comparative Example 3 The coarsely crushed material obtained in Example 2 was pulverized using a mechanical pulverizer using a rotor and a liner, and classified in the same manner as in Example 1 to produce magnetic toner I as shown in Table 1. I got it.

Table 2 shows the results of an evaluation test conducted in the same manner as in Example 1 using the same external additives as in Example 2. Although good images were obtained initially, coating unevenness occurred on the sleeve and H during durability. occurs,
An image defect has occurred.

Comparative Example 4 Crushed material obtained using the above materials in the same manner as in Example 1 was crushed to 3 kg/c+ using a pulverizer using a jet stream.
Fine pulverization was repeated three times at an air pressure of s2, and the mixture was classified in the same manner as in Example 1 to obtain magnetic toner J as shown in Table 1.

Table 2 shows the results of conducting the same evaluation test as in Example 1 with the same external additions as in Example 1.

Initially, the image was good, but during durability, sleeve coating unevenness occurred and image defects occurred.

Comparative Example 5 (3 parts of low molecular weight ethylene-propylene copolymer) Magnetic toner K as shown in Table 1 was prepared in the same manner as in Example 1 using the above materials.

Example 1 This magnetic toner was externally added in the same manner as in Example 5.
Table 2 shows the results of the same evaluation.

As a result, the image density was low and there was some fog, but the resolution and fine line reproducibility were excellent.

0 Good x Occurrence Table 2 [Effects of the Invention] Since the present invention has a magnetic toner having a specific particle size distribution and a friction zone of 7 ftm, it exhibits the following excellent effects.

(1) A magnetic toner that uniformly sleeve-neats under any environment and with any developing sleeve.

(2) A magnetic toner that coats the sleeve uniformly even when using a developing sleeve that rotates at high speed.

(3) It is a magnetic toner that has a high image tC degree, excellent fine line reproducibility, 9-level resolution, and provides clear images without fog over a long period of time.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view of a developing device using a magnetic blade, FIG. 2 shows a diagram explaining the causes of uneven toner coating, and FIG. 3 shows a diagram explaining the definition of surface roughness and pitch. FIG. 4 shows a schematic explanatory diagram of the transfer 9 separation device,
FIG. 5 shows a schematic explanatory diagram of the developing device, and FIG.
Friction zone of magnetic toner', t i measurement! A schematic explanatory diagram of the I device is shown. FIG. 7 is a diagram showing a graph in which the coefficient of variation of the number distribution of magnetic toner and the value of the amount of triboelectric charge (I&c/g) are plotted. Ia...Magnetic blade, 2...Sleeve. 3... Applied magnetic toner, 4... Fixed magnet roller, 7... Developer container, 9... Photosensitive drum,
lO... Magnetic toner, 11... Alternating voltage power supply, 22... Transfer device, 23... Separation device, 24... Transfer material, 32... Measuring container,
33... Screen, 39... Electrometer.

Claims (1)

[Scope of Claims] A magnetic toner having at least a binder resin and a magnetic powder has a volume average particle diameter in the range of 7 to 10 μm, and the number distribution of magnetic toner particles and the amount of triboelectric charge are expressed by the following general formula (1).
) A magnetic toner that satisfies the following. Q (μc/g) = 0.1 (μc/g) A+K (μc/g
)...(1) [However, 4≦K≦12 (μc/g)25
Indicates a positive number ≦A≦45, A indicates the coefficient of variation of the number distribution S/@D@_1×100, S indicates the standard deviation of the number distribution of magnetic toner, @D@_1 indicates the number average particle diameter (μm), and Q indicates the amount of frictional electrification with the iron powder carrier. (μc/g)]