JP2931643B2 - Electrostatic latent image developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrostatic latent image developer containing magnetic toner particles,
And an electrostatic latent image developer containing magnetic toner particles and carrier particles.

<Conventional Technology> As a developer for developing an electrostatic latent image, a one-component developer using a magnetic toner is widely known.

Charged magnetic toners in which a charge control agent is added to magnetic toners are also known (JP-A-55-48754 and JP-A-57-455).
No. 55, No. 57-45556, No. 57-45557).

Further, in order to prevent charge aggregation of the toner and reduce image defects such as white stripes, Japanese Patent Application Laid-Open Nos.
182464, 59-210450, 59-210466, 59-21
No. 6149, No. 62-42163, No. 62-275280, No. 62-29425
In the publications such as No. 9 and the like, a charged chromium complex of a monoazo dye such as Bontron S-34 (manufactured by Orient Chemical Industries) and a pontron N-01 (same as above) which is a nigrosine dye are internally added to a toner as a charge control agent. It is disclosed that carrier particles are further added to the magnetic toner.

The magnetic toner used for these various developers is usually a magnetic powder dispersed in a resin, and contains various charge control agents, pigments, and the like as necessary.

As the magnetic powder, various metals such as iron, manganese, cobalt, nickel and chromium, or alloys thereof, or metal oxides such as chromium oxide, iron sesquioxide and triiron tetroxide are usually used. Japanese Patent Application Laid-Open No. 60-32859 discloses the use of magnetic particles made of an amorphous alloy.

This publication describes an example in which magnetic particles of an amorphous alloy are used as a carrier. The magnetic particles of the amorphous alloy have good surface properties due to the manufacturing method, and when used as a carrier, there is no toner adhesion, and image deterioration is observed even after performing hundreds of thousands of copy runs. It cannot be done. Further, since the amorphous alloy is hard to rust, fogging is prevented.

However, the publication does not disclose an example in which magnetic particles made of an amorphous alloy are internally added to a magnetic toner.

<Problems to be Solved by the Invention> The present inventors prepared magnetic toner particles by internally adding amorphous magnetic alloy particles to toner particles, and prepared the above-described one-component developer and further carrier particles. It was applied to the contained developer.

As a result, it was found that the desired image density could not be obtained because the amorphous magnetic alloy particles were lighter in color than metal oxides such as chromium oxide, iron sesquioxide, and triiron tetroxide.

In this case, the magnetic toner particles tend to adhere to the sleeve, and when carrier particles are used in combination, carrier pulling tends to occur.

The present invention has been made in view of such circumstances, and has a good developing characteristic, a sufficient image density, little adhesion of a magnetic toner to a sleeve, and an extremely small electrostatic latent image. It is an object to provide an image developer.

<Means for Solving the Problems> As a result of repeated studies, the present inventors have found that the above object is achieved when crystalline black magnetic particles are used in combination with amorphous magnetic alloy particles, The present invention of the following (1) to (8) has been completed.

(1) An electrostatic latent image developer containing magnetic toner particles, wherein the magnetic toner particles contain a magnetic powder and a resin, and the magnetic powder contains amorphous magnetic alloy particles and black magnetic particles. An electrostatic latent image developer comprising:

(2) The method according to the above (1), wherein the ratio of the content of the amorphous magnetic alloy particles to the total of the content of the amorphous magnetic alloy particles and the content of the black magnetic particles is 40 to 90% by weight. Electrostatic latent image developer.

(3) The content of the magnetic powder in the magnetic toner particles is 10 to 70.
The electrostatic latent image developer according to the above (1) or (2), which is in terms of% by weight.

(4) The average particle diameter of the amorphous magnetic alloy particles is 0.1 to 2
μm, and the average particle diameter of the black magnetic particles is 0.04 to 1.
The electrostatic latent image developer according to any one of the above (1) to (3), which has a thickness of 2 μm.

(5) The electrostatic latent image developer according to any one of (1) to (4) above, wherein the average particle diameter of the magnetic toner particles is 5 to 30 μm.

(6) The electrostatic latent image developer according to any one of the above (1) to (5), further comprising carrier particles.

(7) The electrostatic latent image developer according to (6), wherein the carrier particles have an average particle diameter of 10 to 45 μm.

(8) The electrostatic latent image developer according to the above (6) or (7), wherein the content of the carrier particles is 10 to 40% by weight.

<Operation> In the present invention, amorphous magnetic alloy particles are used as the magnetic powder added to the magnetic toner.

Since the amorphous magnetic alloy particles have a large maximum magnetization σ _m , the content for forming magnetic toner particles having a predetermined magnetization is small. For this reason, the solid content that does not deform when fixing the magnetic toner can be reduced, and the fixability is improved.

In the present invention, the lack of image density due to the light color of the amorphous magnetic alloy particles is compensated for by the addition of black magnetic particles.

Further, when only amorphous magnetic alloy particles are used as the internal magnetic powder, adhesion of the magnetic toner to the sleeve and carrier pulling are liable to occur, but these can be prevented by using black magnetic particles in combination.

<Specific Configuration> Hereinafter, a specific configuration of the present invention will be described in detail.

The electrostatic latent image developer of the present invention contains magnetic toner particles, and the magnetic toner particles contain a magnetic powder and a resin.

In the present invention, the magnetic powder contained in the magnetic toner particles contains amorphous magnetic alloy particles.

As the composition of the amorphous magnetic alloy, an arbitrary alloy composition such as one composed of a ferromagnetic transition metal and a semimetal, or one in which a small amount of another element is further added thereto can be used.

1 to 3 kinds of ferromagnetic transition metals such as Fe, Co, Ni,
In particular, those mainly composed of Fe or Co, semimetals such as B,
It is mainly composed of Si, C, P, Ge, especially B, Si,
Preferred are Fe-B-Si ternary system, Co-B-Si ternary system, Fe
-Co-B-Si4 element system and the like.

In addition, 10% or less of Cr, Mn, Mo, Nb, A
At least one of l, Ti, V, Sn, Zn, and Cu may be added.

The alloy composition in this case is preferably represented by the following formula.

Wherein _{T u M x (Si, B} ) w However, in the above equation, expressed in at%, x = 0 to
20, preferably x = 2-10, w = 15-37, preferably w
= 18-30, u = 100- (x + w).

 T is one or two of Fe and Co.

M is at least one selected from the group consisting of Ti, V, Nb, Ta, Cr, Mo, W, Mn, and Ni. Of these, only Cr or Cr is essential in terms of corrosion resistance, and the other one is used. It is preferable to include the above.

More specifically, when Cr is added, the addition amount is preferably 2 to 10 at%, and Nb, Mo, W, Ta, V, Ti, Ni
In particular, when one or more of Nb, Mo, and Ni are added, the addition amount is preferably 1 to 10 at%.

By setting the addition amount in such a range, the corrosion resistance and the brittleness are improved, and the saturation magnetization is not reduced. Also, w
= 15 to 37 is an amorphous formation region.

Such an amorphous magnetic alloy can be manufactured by any conventionally known rapid quenching method. Examples of such a production method are described in JP-B-61-4302. For example, an ingot of a predetermined alloy composition is melted at a high temperature, sprayed on a rotating steel single roll or the like, and cooled at a high speed, and the obtained ribbon or scale is roughly pulverized to coarse particles. I do.

Coarse pulverization may be performed by any known method, and a granular powder having an average particle diameter of several μm to about 50 μm or a powder having a similar size produced by a known powder production method such as a water atomizing method is used.

 The rapidly quenched alloy is then subjected to a grinding process.

For the pulverization, it is preferable to use a medium stirring mill such as a pin mill (or a bead mill), particularly a pin mill. The pin mill is described in, for example, JP-A-61-259739. The pin mill has a large number of pins erected on opposing surfaces of the inner and outer cylinders, filled with beads as a medium, and the inner and outer cylinders are rotated at a relatively high speed.

 The obtained particles may be subjected to a heat treatment.

The shape of such amorphous magnetic alloy particles may be spherical, crushed, or flake.

The average particle size is preferably from 0.1 to 2 μm, more preferably from 0.5 to 1 μm.

When the average particle diameter is less than the above range, the magnetization σm becomes low, and the characteristic of the amorphous alloy, ie, high magnetization, tends to deteriorate. If the ratio exceeds the above range, the fixing property tends to deteriorate, and the dispersion of the magnetic powder in individual toner particles tends to deteriorate.

In this case, the average particle size is measured by the following method.

The specific surface area (BET one-point method) Sw is actually measured by BET one-point method using Micromeritex Flow Soap Model 2300 manufactured by Shimadzu Scientific Instruments.

Then, the average particle size D may be determined from the relationship between the particle size and the specific surface area.

Sw: specific surface area (actual value) Di: particle size ni: number of particles ρ: powder density In the present invention, the magnetic toner particles contain crystalline black magnetic particles in addition to the amorphous magnetic alloy particles.

As the black magnetic particles used in the present invention, the brightness, that is, the reflectance is lower than the amorphous magnetic alloy particles used in combination, the difference in reflectance depending on the wavelength is small, preferably a black or a color close to it, There is no particular limitation as long as it has magnetic properties that can be used for magnetic toner particles.

As such black magnetic particles, for example, the general formula MO
・ Fe ₂ O ₃ (M is Fe, Mn, Co, Ni, Mg, Zn, Cd, B
a, Li, Cu, V, Cr, and Ca), and a compound having a spinel structure having a composition represented by formula (1), and Fe ₃ O ₄ is particularly preferable.

In addition, CrO ₂ can also be used.

The ratio of the content of the amorphous magnetic alloy particles to the total content of the amorphous magnetic alloy particles and the black magnetic particles in the magnetic toner particles is preferably 40 to 90% by weight. If the ratio is less than the above range, the fixability tends to be insufficient. If the ratio exceeds the range, the image density becomes insufficient, and the magnetic toner particles tend to adhere to the sleeve and to the carrier.

The average particle diameter of the black magnetic particles is 0.04 to 1.2 μm
It is preferred that

If the average particle size is less than the above range, the maximum magnetization σm tends to be low, and if the average particle size exceeds the above range, the coloring effect tends to be low and the dispersion in the toner particles tends to be poor.

Incidentally, the coercive force Hc of the amorphous magnetic alloy particles used in the present invention.
Is usually about 1 to 90 Oe at 1000 Oe, and the coercive force Hc of the black magnetic particles is usually about 30 to 150 Oe at 1000 Oe.

The maximum magnetization σm at 1000 Oe of the amorphous magnetic alloy particles is usually about 70 to 120 emu / g,
The maximum magnetization σm at Oe is usually about 50 to 80 emu / g, and when the particle diameter is the same, the maximum magnetization σm of the amorphous magnetic alloy particles is usually larger.

In the present invention, in addition to amorphous magnetic alloy particles and black magnetic particles, iron, manganese, cobalt, nickel, metals such as chromium or alloys thereof, various magnetic particles conventionally known as magnetic materials, May be used.

In this case, the total content of the amorphous magnetic alloy particles and the black magnetic particles in the magnetic powder is preferably 80% by weight or more, and most preferably 100% by weight. If it is less than the above range, the effects of the present invention will be insufficient.

The content of the magnetic powder in the magnetic toner particles is 10 to
Preferably it is 70% by weight, especially 15-60% by weight.

If the amount is less than 10% by weight, the magnetic force from the magnet inside the developing machine is not sufficiently transmitted, and fog and toner scattering tend to be deteriorated. If it exceeds 70% by weight, the fixability of the toner tends to deteriorate.

As the resin contained in the magnetic toner, a styrene copolymer resin is particularly suitable.

The styrene copolymer resin is obtained by a copolymerization reaction between a styrene monomer and a copolymerizable vinyl monomer.

In this case, the copolymerizable monomers include styrene and its derivatives, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate,
Α-ethylhexyl acrylate, α-hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, Acrylic esters or methacrylic esters such as α-hydroxyethyl methacrylate and hydroxypropyl methacrylate; amides such as acrylamide, diacetone acrylamide and N-methylol acrylamide; and other vinyl esters, ethylene-based olefins, and ethylene-based And unsaturated carboxylic acids.

 In addition, a polyester resin can also be used.

The polyester resin is obtained by a polycondensation reaction between a polybasic acid component and a polyhydric alcohol component.

As the polybasic acid in this case, oxalic acid, malonic acid,
Succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebecinic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-
Examples thereof include resin group polycarboxylic acids represented by cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid, aromatic polycarboxylic acids, alicyclic polycarboxylic acids, and anhydrides thereof.

As polyhydric alcohols, ethylene glycol, propylene glycol, trimethylene glycol,
1,4-butanediol, 1,5-pentanediol, 1,6-
Hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, pinacol, hydrobenzoin, benzpinacol, cyclopentane-1,2-diol, cyclohexane- Examples thereof include aliphatic polyalcohols represented by 1,2-diol and cyclohexane-1,4-diol, aromatic polyalcohols, and alicyclic polyalcohols.

As other resins, epoxy resin, silicone resin, fluorine resin, polyamide resin, acrylic resin, polyurethane resin, polyether resin, polyvinyl alcohol resin, polyethylene, ethylene-vinyl acetate copolymer,
Polypropylene and the like.

These resins may be used alone, but may be used as a mixture of two or more as needed. Further, as a production method of these resins, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a bulk polymerization method, a thermal polymerization method, a contact polymerization method, a high-pressure polymerization method, a low-pressure polymerization method and an appropriate one of these polymerization methods are used. It can be produced by a conventionally known polymerization method such as a combination.

In the present invention, the average particle size of the magnetic toner particles is 5
It is preferably from 30 to 30 μm, more preferably from 5 to 25 μm.

When the average particle diameter is less than 5 μm, the fluidity of the developer is deteriorated, and caking or sleeve adhesion of the developer is likely to occur. When the average particle diameter is more than 30 μm, the resolution is deteriorated and the fixability tends to be poor. .

To measure the average particle size of the toner particles, the volume particle size of the measured value was calculated by the Coulter counter method, and the 50
% The average particle diameter is defined as the average particle diameter.

In the Coulter counter method, Isoton II (manufactured by Coulter Electronics) is used as an electrolyte,
For example, a coulter counter TA with an aperture diameter of 100 μm
Perform volume-based measurements using -II (from Coulter Electronics).

In general, the particle size distribution is preferably such that the average particle size is 2% or more and about 5% or less, and / 2 or less is about 5% or less.

Various internal additives may be further added to such magnetic toner particles.

 One example of the internal additive is a wax.

Waxes are for so-called offset development measures that occur during fixing by a fixing roll,
For example, low molecular weight polyethylene, polypropylene, metal salts of fatty acids, and silicone oil are used.

Such materials include polyethylene such as High Wax 100P and High Wax 110P [Mitsui Petrochemical Industry Co., Ltd.], polypropylene such as Viscol 550P and Viscol 330P [Sanyo Chemical Industry Co., Ltd.], and zinc stearate 60.
1. Fatty acid metal salts such as zinc stearate CP [Nitto Kasei Kogyo] and silicone oils such as silicone oil KF96 and silicone oil KF69H [Shin-Etsu Silicone Co., Ltd.].

A fluorine resin is also effective as a release agent having such a function.

These substances having a releasing action are preferably contained in an amount of 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, per 100 parts by weight of the toner particles.

Carbon black MA-100 [Mitsubishi Kasei Kogyo Co., Ltd.], Ketjen Black EC-DJ600 [Lion Akzo Co., Ltd.], 671 Miloli Blue [Dainichi Seika Kogyo Co., Ltd.] And inorganic or organic pigments such as conductive titanium oxide (Titanium Industry Co., Ltd.).

These are preferably contained in an amount of 0.1 to 10 parts by weight, particularly 0.1 to 5 parts by weight, per 100 parts by weight of the toner particles.

In addition, examples of the internal additive include a fluidity improver and a resistance adjuster described below.

As described above, the magnetic toner particles contain the magnetic powder and the resin, and further contain waxes, pigments, and the like as necessary.

The charge control agent is added as needed to control the charge polarity, charge amount, and the like. In the present invention, an appropriate known charge control agent may be selected according to the intended polarity, charge amount, and the like, and there is no particular limitation. For example, metal complex salt azo dyes, nigrosine dyes and the like can be mentioned, and these are selected according to required characteristics.

The content of such a charge control agent is 100
It is preferably about 0.1 to 5 parts by weight based on parts by weight.

To such magnetic toner particles, a resistance adjusting agent, a color adjusting agent or a coloring agent, a fluidity improving agent and the like can be externally added.

Examples of these are colloidal silica, titanium oxide,
Metal oxides such as zinc oxide and alumina; inorganic fine powders such as silicon carbide, calcium carbonate, barium carbonate and calcium silicate; polymer beads such as PMMA, polyethylene, nylon, silicone resin, phenolic resin, benzoguanamine resin, polyester; Fluorinated organic fine powders such as ethylene fluoride, polytetrafluoroethylene, and polyvinylidene fluoride; fatty acid metal salts such as zinc stearate and magnesium stearate; black pigments such as carbon black, acetylene black, channel black, and aniline black; Yellow pigments such as Light Yellow GR and Bioreel Yellow 1090, red pigments such as Permanent Red E5B and Rhodamine 2B, blue pigments such as copper phthalocyanine and cobalt blue, and green faces such as Pigment Green B , And the like orange pigments such as pyrazolone orange.

Although these substances may be used alone,
If necessary, two or more types can be used in combination.

 Further, the above-mentioned release agent can be externally added.

These may be, as described above, kneaded by being internally added to the toner particle composition, or may be externally added and dry-mixed or thermally or mechanically fixed to the surface of the toner particles. For example, when necessary, the forms can be combined as needed.

Further, each substance may be subjected to a coupling agent of a titanate type, an aluminum type, a silane type or the like, a silicone oil, other organic treatments, or an inorganic treatment for a surface hydrophobic treatment or a surface dispersion improving treatment.

These external additives have a particle size of about 0.01 to 5 μm. The external addition amount is about 0.1 to 5% by weight.

Magnetic particles may be further externally added to such magnetic toner particles.

As the magnetic particles to be externally added, it is preferable to select from the same magnetic particles as those of the above-mentioned internally added magnetic powder.

In this case, more preferable results are obtained when the average particle diameter of the externally added magnetic particles is 0.05 to 20% of the average particle diameter of the magnetic toner particles.

The coercive force Hc of the magnetic particles used is, for example, 1000 Oe, 6
It is preferably from 0 to 250 Oe, particularly preferably from 70 to 220 Oe.

As a result, the effect of preventing the adhesion of the sleeve is further enhanced.

Further, for example, the maximum magnetization σm of the magnetic particles and the magnetic toner particles at 1000 Oe is preferably 60 to 100 emu / g and 10 to 50 emu / g, respectively. This allows
The image quality and the effect of preventing the adhesion of the sleeve are further improved.

Such magnetic particles are externally added to the magnetic toner particles.

That is, the magnetic particles are dry-mixed with the magnetic toner particles, mixed with the magnetic toner particles, adhered, adsorbed or adhered to the particle surface, and further adhered to the toner particle surface due to mechanical strain or heat. They are integrated or embedded.

Such magnetic particles are used in an amount of 0.1 to 1 with respect to the magnetic toner particles.
It is preferable to add 0% by weight, particularly 1 to 8% by weight.

If it is less than 0.1% by weight, the effect of external addition is not obtained, and if it exceeds 10% by weight, fog increases and the fixing rate tends to deteriorate.

The magnetic properties of the magnetic toner obtained by externally adding the magnetic particles to the magnetic toner particles as required, for example, are preferably such that the coercive force Hc at 1000 Oe is 20 to 250 Oe, particularly 30 to 220 Oe.

When Hc exceeds 250 Oe, the spikes of the toner become hard, and the toner concentration tends to decrease.

Further, the maximum magnetization σ _{m at} 1000 Oe is preferably ₁₀ to 50 emu / g.

When sigma _m exceeds 50 emu / g, the developing property deteriorates, there is a tendency to lower the density, also when less than 10 emu / g, toner scatter tends to occur.

The bulk density is 0.2 to 0.8 g / cm ³ , especially 0.4 to 0.7 g / cm ³
It is preferred that

In order to manufacture such a magnetic toner, as one example, the raw material composition is sufficiently mixed with a Henschel mixer,
Then, the mixture is kneaded by a hot-melt kneader. Then cool down,
After coarse grinding with a hammer mill, fine grinding is performed with a jet impact mill.

Then, after removing the excess fine powder area by an air classifier, after dry mixing the external additives and magnetic particles as necessary with a Henschel mixer, the excess coarse powder area was removed by an air classifier, A toner having a predetermined particle size distribution is obtained.

Of course, various other known methods may be used.

The electrostatic latent image developer of the present invention, in addition to the magnetic toner particles,
It may contain carrier particles and can be selected according to the purpose.

The carrier particles contained in the developer of the present invention preferably have an average particle diameter of 10 to 45 μm, more preferably 10 to 35 μm.

When the average particle size exceeds 45 μm, the resolution is deteriorated, and the inside of the apparatus due to toner scattering tends to occur.

On the other hand, when the thickness is less than 10 μm, white spots in a solid black pattern called carrier particle pulling tend to occur.

In this case, the average particle diameter is represented by a 50% particle diameter in calculating a volume particle diameter of a measured value by the Microtrack method. That is, a sample dispersed in water using a dispersant is used, for example, in Microtrac STD (799).
It may be calculated from data obtained by performing a volume-based measurement using a 1-0) type (manufactured by LEEDS & NORTHRUP).

There is no particular limitation on the material of the carrier particles used, and various soft magnetic materials such as iron, magnetite and various ferrites can be used.

In this case, as the ferrite, any of various known compositions such as Mg-Cn-Zn ferrite, Ni-Zn ferrite, and Cu-Zn ferrite can be used.

These carrier particles may have a coating of an acrylic resin, a styrene resin, a silicone resin, a fluorine resin, or the like, if necessary, or a polyester resin, a styrene-acryl resin, or the like, as in the case of a toner described below. May be included.

The coercive force Hc of such carrier particles is 1000 Oe1 = 250
Oe or less, more preferably 20 Oe or less at 1000 Oe. This is because if it exceeds 50 Oe, there is a tendency for transport failure.

Also, for example, the maximum magnetization σ _m at 1000 Oe is 10 to 150 emu /
g, more preferably 20 to 100 emu / g, and particularly preferably 20 to 70 emu / g for ferrite carrier particles.

When σ _m is less than 10 emu / g, carrier particles tend to scatter, and when σ _m exceeds 150 emu / g, the brush of the magnetic brush becomes hard and scratches on the photoreceptor tend to occur.

These magnetic properties may be measured using a vibrating magnetometer. Furthermore, the magnetoresistance is 1 × 10 ⁵ Ω when 100 V is applied.
As described above, it is particularly preferable to be about 2 × 10 ⁶ to 2 × 10 ¹² Ω.

If it is less than 1 × 10 ⁵ Ω, the brush streak tends to increase, and if it is too large, the density tends to be hard to appear.

 The measurement of the electric resistance is performed as follows.

That is, 0.2 g of carrier particles are put between parallel metal plates spaced apart by 7 mm, and the carrier particles are sandwiched by magnets from the outside of the metal plates. Then, for example, SM
Start applying voltage from 10V with -10E or SM-5 (both manufactured by Toa Denpa Co., Ltd.), and apply voltage sequentially to 1000V. The direct reading at this time may be used as the electric resistance.

In order to produce such carrier particles, for example, the following may be performed. First, a soft magnetic material is put into a mixer, mixed in a slurry state, and further crushed by an attritor.

These are granulated and dried with a spray drier, and further classified with a shifter.

These are fired in an electric furnace, and these are roughly crushed by a crusher and then crushed by a vibration method.

After that, shifter,
Adjust the particle size using an air classifier. If necessary, it can be coated with a coating machine, and after heat treatment, the particle size can be adjusted again to obtain coated carrier particles.

Further, it is of course possible to produce the image by using other various known methods.

Such magnetic toner particles and carrier particles are mixed at an initial concentration of 10 to 40% by weight of carrier particles,
It is a developer.

If the initial carrier particle concentration in the developer exceeds 40% by weight, stability such as density, fogging, resolution and the like in critically large number of copies, especially in continuous multiple copy, deteriorates.

On the other hand, when the content is less than 10% by weight, toner aggregation, which should be originally improved, occurs, and white stripes tend to occur.

In such a case, more preferable results can be obtained when the initial concentration of the carrier particles is 12 to 38% by weight, particularly 15 to 35% by weight.

At the time of mixing, a Nauta mixer, a V blender, or the like may be used.

In addition, the above-mentioned externally added magnetic particles and certain external additives may be added during this mixing.

Incidentally, the magnetic toner particles may contain a charge control agent, but when carrier particles are contained, an azo dye as a charge control agent, particularly a metal of a monoazo dye, particularly a chromium complex or a nigrosine dye, It is more preferable that they are not contained.

Among the charge control agents, especially in a system in which a metal complex of an azo dye or a nigrosine dye is internally added, especially when the initial toner content in the developer is increased to make the toner rich, toner scattering and an increase in background fog are caused. This is because the density tends to decrease, and toner spent is liable to occur.

The development system to which the electrostatic latent image developer of the present invention is applied is not particularly limited, and can be applied to various systems depending on the purpose.
In particular, a magnetic brush developing system is preferable, and a system in which a developer is magnetically conveyed to a developing area by rotation of a magnet is preferable.

Of these, for example, JP-A-54-119935 and JP-A-55-191993.
No. 32073, etc., having a magnet roll and a developing sleeve roll, wherein the magnet and the developing sleeve rotate in the same or opposite directions, or a fixed developing sleeve in which a rotating magnet roll is built in is preferable. is there.

In addition, the developer of the present invention can be applied to various known developing methods, and the structure of a printer or a copying machine may be any known one.

<Example> Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention.

Example 1 Production of Magnetic Toner Toner Composition A: Toner composition B: The same as the toner composition A except that the amount of the amorphous magnetic alloy particles was 50 parts by weight and no black magnetic particles were contained.

Toner composition C: The same as the toner composition A except that the black magnetic particles were 55 parts by weight and the amorphous magnetic alloy particles were not included.

The toner compositions A, B, and C were sufficiently mixed with a Henschel mixer, kneaded with a hot-melt kneader, cooled, and coarsely ground with a hammer mill. Then, it was pulverized by a jet impact mill.

Next, the excess fine powder area was removed with an air classifier, and the external additive was dry-mixed with a Henschel mixer. Thereafter, the excess coarse powder area was removed by an air classifier to obtain magnetic toner particles A, B, and C produced from the toner compositions A, B, and C, respectively.

These magnetic toner particles each have a volume average particle diameter of 11 ± 0.5 μm, particles of 5 μm or less and 20 μm
Each of the above particles was 0.5% or less. Also, 1000
The magnetization and coercivity in Oe are 32-36 emu / g respectively.
And 30-70 Oe.

These magnetic toner particles were applied to an electrophotographic printer, and the following items were evaluated. The results are shown in Table 1 below.

(Image density) It was measured by REFLECTOMETER MODEL TC-6D manufactured by Tokyo Denshoku Co., Ltd.

(Fixing rate) After printing a 1-inch square black solid pattern, rub the black solid image 10 times with a metal cylinder stick (diameter 50mm, weight 1000g) with gauze glued with double-sided tape,
Measure the density before and after rubbing the printed matter respectively,
It was calculated by the following equation.

(Sleeve adhesion) Printing was performed on 1000 sheets with a printer in which 200 g of toner was set, and after 200 g of toner was further added, continuous printing was performed on 100 sheets.

Next, the sleeve surface was blown off with air, and it was visually identified whether or not the aggregate remained in the sleeve shape and whether or not a wave pattern due to the aggregate was generated in the image.

The occurrence of only agglomerates was evaluated as Δ, the occurrence of agglomerates and wavy pattern was evaluated as x, and the absence of sleeve attachment was evaluated as o.

Example 2 carrier manufacturing carrier composition _{(mol%) 10.5Mg (OH) 2 -20ZnO} -7.5CuO-62Fe 2 O 3 placed above composition to the mixer, and mixed in the slurry was further pulverized in an attritor.

This was granulated by a spray drier, dried, and fired in an electric furnace to obtain a carrier base material. This raw material is adjusted to the target particle size by a shifter and a wind classifier,
Carrier particles having an average particle size of 25 μm were obtained. The magnetization of the carrier particles at 1000 Oe was 53 emu / g.

Next, the carrier particles were mixed with the magnetic toner prepared in Example 1 by a V blender to obtain developers A, B and C containing the magnetic toner particles A, B and C, respectively. The initial carrier particle concentration of these developers is
23% by weight.

Using these developers, the same evaluation as in Example 1 and the following evaluation were performed.

 The results are shown in Table 2 below.

(Carrier pull) Three continuous black solid patterns were printed, white spots (white spots) appearing on the image at that time were counted, and the average of the three sheets was obtained.

The effects of the present invention are clear from the above embodiments.

That is, when the developer of the present invention containing the amorphous magnetic alloy particles and the black magnetic particles is used, the fixability is good and a sufficient image density is obtained, and the adhesion of the sleeve and the pulling of the carrier are hardly observed. .

On the other hand, when only amorphous magnetic alloy particles are used as the magnetic powder to be added to the magnetic toner particles, the image density becomes insufficient, the sleeve adheres and the carrier is drawn, and a high-quality image is obtained. I can't.

Also, when not using amorphous magnetic alloy particles in the magnetic powder,
Poor fixability.

<Effects of the Invention> According to the present invention, a high-quality image with good fixability and sufficient image density can be obtained, and there is almost no adhesion of a sleeve and no carrier pull.

Claims (8)

(57) [Claims] 1. An electrostatic latent image developer containing magnetic toner particles, wherein the magnetic toner particles contain a magnetic powder and a resin, and the magnetic powder contains amorphous magnetic alloy particles and black magnetic particles. An electrostatic latent image developer characterized by containing: 2. The ratio of the content of the amorphous magnetic alloy particles to the total of the content of the amorphous magnetic alloy particles and the content of the black magnetic particles is 40 to 90% by weight. Electrostatic latent image developer. 3. The content of the magnetic powder in the magnetic toner particles is as follows:
3. The electrostatic latent image developer according to claim 1, wherein the amount is 10 to 70% by weight. 4. An amorphous magnetic alloy particle having an average particle size of 0.
1-2 μm, the average particle diameter of the black magnetic particles is 0.0
4. The electrostatic latent image developer according to claim 1, which has a thickness of 4 to 1.2 [mu] m. 5. The magnetic toner particles having an average particle diameter of 5 to 30.
The electrostatic latent image developer according to any one of claims 1 to 4, which has a particle size of 1 µm. 6. The electrostatic latent image developer according to claim 1, further comprising carrier particles. 7. The carrier particles have an average particle size of 10 to 45 μm.
7. The electrostatic latent image developer according to claim 6, wherein m is m. 8. The content of the carrier particles is 10 to 40% by weight.
The electrostatic latent image developer according to claim 6, wherein