JPH04107469A - Negative charge black toner and method for controlling density thereof - Google Patents

Abstract

PURPOSE:To contrive the stabilization of the electrostatic property and flowability by incorporating a specified azo metal complex salt as a charge control agent, a hydrophilic inorganic oxide such as alumina particles and a hydrophobic inorganic oxide such as hydrophobic silica particles into nonmagnetic resin particles incorporating a coloring agent. CONSTITUTION:One of the inorganic oxide represented by formula I is a negative charge hydrophobic inorganic oxide A, having >=50muc/g of an absolute value of a triboelectric charge quantity against magnetic particles and 80-300m<2>/g of a relative surface area SA by the BET method, and the other is a hydrophilic inorganic oxide B, having <=20muc/g of an absolute value of a triboelectric charge quantity and 30-300m<2>/g of a relative surface area SB. A is incorporated by a wt.% and B is incorporated by b wt.% for these inorganic oxides A and B and the resin particles incorporating the coloring agent and there are the relations of SA>=SB, a>=b, and 0.3>=a+b>=1.5. In formula I, R1 is halogen atom, R2-R4 are hydrogen atom, nitro group, and alkyl group, etc., (n) being an integer of 0-3, and (m) is an integer of 1-4. Thus the electrostatic property and the flowability are stabilized.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to black toner used in electrophotographic copying devices and electrostatic recording devices used in various applications, and more specifically, to a photodetection automatic toner density control The present invention relates to a negatively chargeable black toner for a color developer used in a developing device.

(Prior Art) In a developing device that uses a two-component developer consisting of toner and carrier, the mixing ratio of toner and carrier is an extremely important factor.

That is, when the toner density falls below the appropriate value, the image density becomes low, and when the toner density exceeds the appropriate value, the toner cannot be sufficiently charged, resulting in inconveniences such as image fogging and toner scattering. occurs.

Therefore, in order to obtain a good image, it is necessary to accurately detect the toner concentration of the developer and to always control it to a constant value.

Regarding ATR (Automatic Toner Density Detection) methods, various proposals have been made in the past, but in particular,
The method of controlling the amount of toner supply by detecting the color of the developer proposed in Publication No. 45, etc. is stable because it is less affected by changes in physical properties such as the bulk density of the developer due to environmental changes and durability. It is widely used today as a means of detecting toner concentration.

The toner concentration detection section of the above photodetection ATR method is as follows:
For example, the one shown in FIG. 1 is generally known.

As shown in FIG. 1, a sensor window 13 made of a transparent material is provided at a predetermined location on a developer transport path A consisting of toner and carrier, and the sensor window 13 passes through the sensor window 13 to form a developer transport path. Lamp (light source) 1 that irradiates light to the developer in A
0, a first sensor 11 that receives reflected light reflected by the developer, and a second sensor 1 that directly receives light from the lamp 10.
It is composed of 2.

This optical detection type automatic toner density detection method is the first
The toner concentration is detected from the difference between the voltage outputted by the sensor 11 upon receiving reflected light from the developer and the voltage outputted by the second sensor 12 upon directly receiving the light from the lamp 10.

However, in the photo-detection ATR method as described above, since the developer comes into direct contact with the toner concentration detection device, the surface of the sensor window 3 may be damaged due to rubbing against the carrier, or normal charge may occur due to contact with the carrier. There is a problem in that toner with a small amount of charge or toner charged with the opposite polarity adheres to the surface of the sensor window 13, which cannot occur with toner that has been charged.

Generally, the toner adhering to the surface of the sensor window 13 can be removed by rubbing when the developer comes into contact with the window surface, but the rubbing ability of the developer depends on the high toner concentration. As the amount of toner with a smaller charge amount increases, the amount of charge tends to decrease more easily.

Therefore, when toner adheres to the surface of the sensor window 13, the sensor determines that there is enough toner and stops toner replenishment, so the toner concentration of the developer decreases and as a result, the developer is rubbed off. The capacity is restored and the toner adhering to the window surface is removed. When the toner adhering to the surface of the window portion 13 is removed in this manner, the sensor determines that there is a shortage of toner and rapidly starts toner replenishment.

As a result, the toner concentration increases rapidly, and a new area is added to the window 13.
A vicious cycle of toner adhesion to the surface is repeated.

When toner adheres to the surface of the sensor window section 13 in this way, the control range of toner concentration becomes wider (the fluctuations in toner density become wider), resulting in image defects such as fluctuations in image density, fogging, and toner scattering.

This tendency becomes more pronounced when the toner particle size is reduced for the reasons described below.

In other words, as the particle size of the toner becomes finer (as the specific surface area of the toner increases, the amount of charge becomes excessive due to contact charging with the carrier, the miscibility with the carrier decreases, or the cohesiveness of the toner itself increases). This causes a new problem of deterioration.If the mixing property deteriorates and the toner and carrier cannot be mixed and stirred uniformly, the toner will not be charged uniformly, and as a result, the toner will be charged broadly when it comes into contact with the carrier. This results in a toner that is not fully charged or a toner that is charged to the opposite polarity.

These toners that cannot be charged normally tend to adhere to the sensor window 13, especially in a photo-detection type automatic toner concentration control device that has the sensor window 13. Therefore, if the toner particle size is reduced, the sensor as described above Dirty windows become an even more serious problem.

(Problem to be solved by the invention) However, as image forming apparatuses such as electrophotographic color copying machines have become widespread and their uses have expanded to a wide variety, the demands for image quality have become even more demanding. This is becoming increasingly difficult, and reducing the particle size of toner is an essential technique in this technical field.

Furthermore, in this technical field, polyester-based resins are widely used as binder resins for color toners due to their high negative chargeability and excellent fixing properties. Frictional charging is easily affected by temperature and humidity, and for this reason, problems such as excessive charge amount in low temperature and low humidity conditions and insufficient charge amount in high temperature and high humidity conditions tend to occur, and toner chargeability due to environmental changes may occur. Shaking is also becoming a serious problem.

As mentioned above, there are many problems faced when trying to further reduce the particle size of toner, and among them, improving charging characteristics is a major challenge that stands in the way, and this point is the most important point in toner development.

Therefore, an object of the present invention is to provide a negatively chargeable black toner for color developers which solves the above-mentioned problems.

Another object of the present invention is to provide a negatively chargeable black toner with high image density (and excellent fine line reproducibility and highlight gradation) and a photodetection automatic toner density control device using the same.

Another object of the present invention is to provide a negatively chargeable black toner which has a stable toner concentration even during long-term use and whose performance does not change even with environmental changes.

Furthermore, another object of the present invention is to provide a negatively chargeable black toner that can provide high image density with a small amount of colorant and a small amount of toner consumption.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a two-component developer containing at least nonmagnetic colorant-containing resin particles comprising a charge control agent, two or more types of colorants, and a binder resin, and two or more types of inorganic oxides. In the black toner applied to the above, the charge control agent is represented by the following general formula [1], and one of the inorganic oxides has an absolute value of triboelectric charge amount of 50 μm with the magnetic particles.
c/g or more, and specific surface area SA by BET method is 80~
300 m'/g negatively charged hydrophobic inorganic oxide A,
The other of the inorganic oxides has an absolute value of triboelectric charge with the magnetic particles of 20 μc/g or less, and a specific surface area Sl by the BET method.
] is 30 to 300 m/g of hydrophilic inorganic oxide B,
In addition, these inorganic oxides A and B contain 8% by weight of A and 5% by weight of B, respectively, based on the colorant-containing resin particles, and SA≧Sa, a≧b, 0.3≦a+b ≦
1.5, and is a negatively charged black toner whose density can be controlled by a photodetection automatic toner density control device having a photodetection section made of a transparent material.

(In the formula, R1 represents a halogen atom, R2 is a hydrogen atom,
Nitro group, alkyl group, amino group, alkylamino group,
It represents an alkoxy group or an acetoxy group, n represents an integer of 0 to 3, and m represents an integer of 1 to 4. Further, R3 and R4 are hydrogen atoms, alkyl groups, amino groups, alkylamino groups, carboxyl groups, lower alkyl groups, lower alkoxy groups,
It represents a nitro group or a halogen atom, and ρ represents an integer of 1 to 2. M represents chromium, iron, aluminum or cobalt, and A○ represents a counter cation such as a hydrogen ion, sodium ion, potassium ion or ammonium ion. ) (Function) As a result of intensive research into the above-mentioned problems, the present inventors added an azo metal complex salt as a charge control agent to non-magnetic colorant-containing resin particles containing two or more types of colorants. When a black toner is made by containing a hydrophilic inorganic oxide such as alumina particles and a hydrophobic inorganic oxide such as hydrophobic silica particles,
The present invention was completed by discovering that the toner satisfies both stable chargeability and fluidity at the same time, and can function satisfactorily as a toner suitable for a developing device having an automatic photo-detection toner density control device.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

Generally, in order to cause toner to retain electric charge, the triboelectric charging properties of resin, which is the main component of toner, are mainly utilized.

However, with this method, it is difficult to uniformly control the chargeability of the toner, and for example, there may be variations in the charge amount depending on manufacturing lots, instability of chargeability before and after durability tests, and even fluctuations in chargeability due to environmental changes. The reality is that it is difficult to always maintain uniform and stable triboelectric chargeability of toner, which is the most required of toner for electrophotography.

Therefore, today, in order to add more charge to the toner or to make the toner's triboelectric charging properties more uniform and stable, substances called charge control agents are added to control the charging characteristics of the toner. It is common to
Many toners employ this type of material.

There are many charge control agents known in the technical field today, such as metal complexes of monoazo dyes, metal complexes of zarydylic acid, metal complexes of naphthoic acid, and metal complexes of dicarboxylic acids. A charge control agent that is satisfactory in all respects such as properties, stability, and durability has not yet been known.

In particular, there is an urgent need to develop a better charge control agent for toners such as the toner of the present invention, in which the binder resin is generally a polyester resin, etc., which has a high negative chargeability, and whose particle size is small and which tends to have a high tripod charge amount. be.

Furthermore, when black toner is used as a black toner for a full-color copying machine, the biggest issue is the charging stability of the toner, which governs the stability of color reproducibility, gradation, and image density.

As a result of various studies, the present inventors have found that black toner has stable charging properties when it contains a charge control agent represented by the following general formula [I].

(In the formula, R1 represents a halogen atom, R2 is a hydrogen atom,
Nitro group, alkyl group, amino group, alkylamino group,
It represents an alkoxy group or an acetoxy group, n represents an integer of 0 to 3, and m represents an integer of 1 to 4. Further, R3 and R4 are hydrogen atoms, alkyl groups, amino groups, alkylamino groups, carboxyl groups, lower alkyl groups, lower alkoxy groups,
It represents a nitro group or a halogen atom, and ρ represents an integer of 1 to 2. M represents chromium, iron, aluminum or cobalt, and AO represents a counter cation such as a hydrogen ion, sodium ion, potassium ion or ammonium ion. ) Many of the charge control agents represented by the above general formula [I] are colored and have not been used as charge control agents for color toners, but in black toners such as the toner of the present invention. is not a particular problem.

In addition, the charge control agent described above has good compatibility with the binder resin used in the present invention and is easily dispersed uniformly, so that a large difference in chargeability between toners is unlikely to occur (and the tribocharge distribution is sharp). Become.

On the other hand, if the triboelectric charge amount distribution is broad, there will be many toners with a small charge amount or toners with an excessively high charge amount, and the presence of toners with a small charge amount will easily cause images to become foggy and unclear. Due to the presence of toner with too high a density, such a toner has a strong adhesion to the carrier and is difficult to fly onto the paper, so that images with low density are generally likely to be obtained.

In addition, some types of charge control agents tend to contaminate sleeves, carriers, etc., and toners using these agents tend to have a reduced amount of charge as the number of copies is increased, or toner that is charged to the opposite polarity, resulting in a decrease in image quality. However, since the above-mentioned charge control agent used in the present invention has good dispersibility in the resin, it does not tend to be localized only on the surface and does not particularly contaminate the sleeve or carrier. There is nothing like that.

As a method for incorporating the above-mentioned charge control agent into toner,
There are two methods: adding it inside the toner and adding it externally.
The present invention is not particularly limited in any way.

When externally added, it is preferable to mechanochemically fix it to the toner particle surface, since it may cause sleeve contamination, change in charge amount, and accompanying image defects due to detachment from the toner surface.

However, it is more preferable to add the charge control agent to the inside of the toner since it is possible to impart stable chargeability to the entire toner.

Further, the amount of the charge control agent added to the toner is determined by the manufacturing method including the type of binder resin and the dispersion method, and is not uniquely limited. However, preferably O per 100 parts by weight of the binder resin.
, 1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight.

The compound [I] used in the present invention can also be used in combination with a conventionally known charge control agent.

As mentioned above, in the negatively chargeable black toner of the present invention,
Although stable triboelectrification is the most required performance, at the same time the toner must also have excellent fluidity.

The present inventors have continued to study the above-mentioned charge control agent and have also continued to earnestly study external additive formulations. As a result, when the toner contains two types of external additives, a hydrophobic inorganic oxide and a hydrophilic inorganic oxide, in addition to the above-mentioned charge control agent, it is possible to achieve both chargeability and fluidity. It was discovered that the characteristics can be controlled simultaneously.

The effects of the hydrophilic inorganic oxide used in the present invention will be explained in detail below.

When a low chargeability hydrophilic inorganic oxide such as alumina particles is externally added to the toner, it functions as a kind of spacer in the frictional charging between the carrier and the toner, and as a result, a region with low charging ability is formed on the toner surface, and the toner suppresses excessive charge amount.

Furthermore, since alumina particles have a strong weakly positive charge series,
It also has the effect of relatively lowering the negative nature of toners using negatively chargeable polyester, and is useful for improving charging characteristics. Therefore, when trying to reduce the particle size of toner, it is essential to use a hydrophilic inorganic oxide with low chargeability such as alumina particles.

Additionally, when toner particles are made smaller in size, the Coulomb force and van der Waals force that act on the toner become relatively stronger compared to gravity and inertial force, which increases the adhesion force between toner particles and causes toner aggregates. However, alumina particles function effectively against this, weakening the adhesion between toner particles and making it difficult to form toner aggregates.

Furthermore, since the presence of alumina particles reduces direct contact between the toner base and the carrier surface, it is effective in reducing toner spent on the carrier surface, and also extends the life of the developer.

As mentioned above, alumina particles are very effective in preventing toner aggregation and suppressing excessive charging, but for the reasons described below, they have a BET specific surface area of 30 m2/g.
(approx. 40mg) ~300rrf'/g (approx. 5mμ)
It must be within the range of 80m2/g, more preferably 80m2/g.
(approximately 25 mu) to 150 r&/g (approximately 15 mμ).

For example, when alumina particles having an ET specific surface area of more than 300 n-1'/g are used, the fluidity is sufficient, but there is a disadvantage that the toner is likely to be susceptible to hydrophilic failure. Peeling deterioration occurs as a phenomenon in which the amount of charge changes significantly or the fluidity of the developer worsens when copying continues with low toner consumption.

In addition, if alumina particles having an ET specific surface area smaller than 30 d/g are used, sufficient fluidity cannot be obtained even when used in combination with other fluidity-imparting agents. Dispersion of the agent tends to be insufficient, which has the disadvantage of causing fog on the image.

However, the BET specific surface area is 30 due to the following reasons.
Even in the range of ~300 d/g, it is necessary to use not only alumina particles alone but also a hydrophobic inorganic oxide such as hydrophobic silica.

That is, in the range of 30 to 300 m2/g, the use of alumina particles alone will result in insufficient fluidity, so it is necessary to use hydrophobic silica or the like, which has a high fluidity imparting effect, in combination.

Furthermore, 1. In the range of OO to 300 m2/g, the surface of the colorant-containing resin particles can be uniformly covered, so if only low-charging alumina particles are used, the amount of charge tends to be extremely low; It is necessary to use a hydrophobic inorganic oxide such as hydrophobic silica in combination.

As described above, hydrophobic inorganic oxides such as hydrophobic silica serve to supplement low chargeability inorganic oxides such as alumina particles in terms of negative chargeability and ability to impart fluidity. For this purpose,
A sufficient effect cannot be obtained unless the BET specific surface area of the hydrophobic inorganic oxide is 80+m'/g or more. More preferably 1
50m2/g or more is preferable.

Further, when alumina particles and a hydrophobic inorganic oxide are used in combination, the fluidity of the toner becomes better than when each is used alone, and the mixing properties of the developer and the toner cleaning properties are also improved.

In order to make the present invention more effective, the BET specific surface area of the hydrophobic inorganic oxide A should be sA, and the BE of the alumina particles B should be
When the T specific surface area is sll, SA≧SB, and A and B should be contained at 8% by weight and B at b% by weight, respectively, so that the following formulas are satisfied for the colorant-containing resin particles. is necessary.

a≧b and 0.3≦a+b≦1.5 In other words, if the amounts of A and B added are in the relationship a<b, or if (a+b) is not within the above range, the chargeability and fluidity If (a+b)>1.5, the fixing properties of the toner will deteriorate, and in particular, the transparency of the toner will decrease.

As the hydrophobic inorganic oxide used in the present invention, 80i/g
Any negatively charged inorganic oxide with a BET specific surface area of 50 μc/g or more and an absolute value of frictional charge with magnetic particles of 50 μc/g or more may be used. It is more preferable to use treated silica fine powder obtained by hydrophobicizing silica fine powder produced by oxidation. Furthermore, it is particularly preferable that the fine silica powder is treated so that the degree of hydrophobicity as measured by a methanol titration test is in the range of 30 to 80.

As a method for hydrophobic treatment, hydrophobicity is imparted by chemical treatment with an organosilicon compound that reacts with or physically adsorbs silica fine powder.

A preferred method is, for example, a method in which fine silica powder produced by gas phase oxidation of a silicon halide compound is treated with an organosilicon compound.

Examples of such organosilicon compounds are hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, benzyldimethylchlorosilane. Silane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, Dimethyldimethoxysilane, diphenyljethoxysilane, hexamethyldisiloxane, 13-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane and terminally located siloxane units having 2 to 12 siloxane units per molecule. Examples include dimethylborisiloxane, each containing one hydroxyl group bonded to Sl. These may be used alone or in a mixture of two or more.

The particle size of the hydrophobized silica fine powder is 0003
It is preferable to use one in the range of ~0.1 μm.

Commercially available products include Taranox 500 (Kurko), A
Examples include ERO3IL R972 (Japan Aerosil Co., Ltd.).

On the other hand, although there are no particular restrictions on the manufacturing method or crystal structure of alumina particles, alumina particles obtained by vapor phase oxidation generally have a sharp particle size distribution, and the particle size can be controlled relatively easily. It is also preferable in that it is possible to do this, and furthermore, it has good dispersibility on the toner surface.

However, even with alumina particles obtained by a wet method, the specific surface area is 30 to 300 r&/g, preferably 80
~150rn''/g is sufficient.

The so-called wet manufacturing methods of high-purity aluminum that are widely practiced today include the ammonium alum thermal decomposition method, the organic ammonium hydrolysis method, the ethylene chlorohydrin method, the underwater spark discharge method, and the ammonium aluminum carbonate thermal decomposition method. Various decomposition methods have been put into practical use, but due to differences in starting material firing temperature, reaction time, etc., even alumina particles with the same chemical structure have significantly different properties depending on each manufacturer. The agglomerated form of -
Differences in particle diameter etc. are extremely likely to occur due to differences in manufacturing methods.

The alumina particles used in the present invention are preferably non-agglomerated, or even if they are agglomerated, they are easy to loosen, and alumina particles that contain tightly aggregated so-called °° particles are not uniformly dispersed on the toner surface. This is not very preferable because it is difficult to use, and the toner particles lack charging stability.Also, particles with extremely angular or acicular shapes are also not preferable.

As the binder resin used in the negatively chargeable black toner of the present invention, various kinds of material resins conventionally known as toner binder resins for electrophotography are used.

For example, styrene copolymers such as polystyrene, styrene-butadiene copolymers, styrene-acrylic copolymers, ethylene copolymers such as polyethylene, ethylene-vinyl acetate copolymers, and ethylene-vinyl alcohol copolymers. , phenolic resin, epoxy resin, acryl phthalate resin, polyamide resin, polyester resin, maleic acid resin, etc. Furthermore, there are no particular restrictions on the manufacturing method of any of the resins.

However, among these resins, the effect of the present invention is particularly great when a polyester resin having a high negative charging ability is used.

That is, although polyester resin has excellent fixing properties and is suitable for color toner, it has a strong negative charging ability and tends to be overcharged. However, when polyester resin is used in the structure of the present invention,
These adverse effects are improved and an excellent toner can be obtained.

In particular, the following formula (wherein R is ethylene or propylene group, X and y
are each an integer greater than or equal to 1, and the average value of x and y is 2=
It is 10. ) as a diol component, and a carboxylic acid component consisting of a bivalent or higher carboxylic acid, its acid anhydride, or its lower alkyl ester (for example, fumaric acid, maleic acid,
A polyester resin obtained by cocondensation polymerization with maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc. is more preferable because it has sharp melting characteristics.

In terms of light transmittance with special nitraben, the apparent viscosity at 90'C is 5 x 10' to 5 x 106 poise, preferably 7
．． 5xlO' to 2xlO6 voids, more preferably 1
05 to 106 voices, ], apparent viscosity at OO''C is 10' to 5X10' voices, preferably 10'
~3X10'boids, more preferably 10'~2X10
'Color OH with good light transmittance due to its voids
P is obtained, and good results are obtained in fixing properties, color mixing properties, and high temperature offset resistance as a full color toner.

Furthermore, the absolute value of the difference between the apparent viscosity P1 at 90°C and the apparent viscosity P2 at 100°C is 2x1.05<P
It is particularly preferred that + -P2 <4xlO6.

The negatively chargeable black toner of the present invention is a toner obtained by blending and mixing two or more types of colorants such as dyes and pigments that are not generally black with a binder resin, and kneading the mixture to obtain a black color.

Colorants suitable for the purpose of the present invention include known dyes and pigments;
For example, copper phthalocyanine, insoluble azo, disazo yellow, anthraquinone pigments, quinacridone pigments, disazo oil-soluble dyes, etc. can be widely used.

In this case, the colorant may be subjected to some kind of surface treatment for the purpose of increasing the affinity between the resin and the colorant.

Particularly preferred pigments include C,I pigment yellow o-
17, C, 1, Pigment Yellow 1, C, I Pigment Yellow 12, C, 1, Pigment Yellow 13, C
,1, Pigment Yellow 14, C,I Pigment Red 5, C,1, Pigment Red 2, C,I Pigment Red 3, C,I, Pigment Red 17, C1I Pigment Red 22, C,I Pigment Red 23, C,
I, Pigment Red 122, C,1, Pigment Blue 15, C,1, Pigment Blue 16, or Ba having the structural formula (TT) shown below and having 2 to 3 carboxybenzamidomethyl groups substituted on the phthalocyanine skeleton
There are copper phthalocyanine pigments which are salts.

(C: uPc-copper phthalocyanine ring, n=2-3) Also, preferred dyes include C,1, Solvent Red 49
, C,1, Solventret 52, C,I Solventret 109, etc., but the present invention is not limited thereto.

The content of the colorant is sensitive to the transparency of the OHP film, so it is better to keep it as low as possible, and it is better to disperse it uniformly in the resin. For example, the content thereof is preferably 0 parts by weight or less, preferably 1 to 7 parts by weight, based on 100 parts by weight of the binder resin.

In particular, in the negatively chargeable black toner of the present invention, which is blackened by mixing and kneading two or more colorants into a binder resin,
Adding a total amount of colorant in excess of parts by weight not only tends to cause spent to the carrier, but also increases concerns about toner drum fusing and fixing properties due to a large amount of colorant being exposed on the toner surface. , the amount of colorant is 100% of the binder resin
It is preferable that the amount is 1 to 7 parts by weight based on the amount of ffi.

A preferred combination of colorants for forming the negatively chargeable black toner of the present invention is a 1+1 combination of pigments such as a disazo yellow pigment, a monoazo red pigment, and a copper phthalocyanine blue pigment. ．． It is preferable to use the colorants in a blending ratio of 5 to 2.5:0.5 to 15, but in the present invention, the above-mentioned colorants may be combined in any way, and there is no restriction on the blending ratio. do not have.

However, as the colorant for the negatively chargeable black toner of the present invention, those having low spectral reflectance in the infrared region, such as carbon black, nigrosine dye, and iron black, cannot be used alone.

That is, in a photo-detection type automatic toner density control device,
Since the toner concentration is detected from the difference between the voltage output by receiving the reflected light reflected by the developer and the voltage output by directly receiving the light from the light source lamp, it has infrared light reflection characteristics above a certain fixed value. This is an essential condition for toners applied to photodetection type automatic toner density control devices.

Therefore, the toner is in the infrared region, especially in the range of 900 to 11,000.
It is preferable that the spectral reflectance in the range of n is at least 30% or more, and it is not possible to use a single colorant such as carbon black, which has low reflection characteristics in the infrared region.

However, there is no problem in using a small amount of carbon black or the like in combination with other colorants in order to slightly adjust the blackness of the black toner of the present invention. If the spectral reflectance in the infrared region is ultimately 30% or more, the black toner of the present invention will function satisfactorily.

Theoretically, if the difference in spectral reflectance between toner and carrier is minute, it should be possible to apply it to a photodetection type automatic toner density control device, but if it is less than 30%, the detection device's ability to detect It is below the limit of the combined power of the factors that determine the detection accuracy, such as the spectral transmittance of the fiber, the spectral transmittance of the gicroic mirror, the S/N ratio of the electrical signal processing circuit, and the assembly tolerance of the detection device, and the carrier and toner cannot be stably identified, and the developer concentration cannot be determined quantitatively.

The magnetic particles used when the negatively charged black toner of the present invention is mixed with magnetic particles to form a two-component developer include:
For example, surface-oxidized or unoxidized metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earths, alloys or oxides thereof, and ferrites can be used.

Moreover, there are no special restrictions on the manufacturing method.

When the density of the negatively chargeable black toner of the present invention is controlled by a photodetection automatic toner density control device, it is preferable to coat the surface of the magnetic particles with a resin or the like.

As a method for this, any conventionally known method can be applied, such as a method in which a coating material such as a resin is dissolved or diluted in a solvent and then applied and adhered to the magnetic particles, or a method in which the coating material is simply mixed in powder form. In order to stabilize the coating layer, it is preferable that the coating material be dissolved in a solvent.

The coating material on the surface of the magnetic particles varies depending on the toner material, but examples include aminoacrylate resin, acrylic resin, copolymers of these resins and styrene resin, silicone resin, polyester resin, polytetrafluoroethylene, etc. , monochlorotrifluoroethylene polymer, polyvinylidene fluoride, etc., but are not necessarily limited thereto.

The most suitable material for the present invention is an acrylic resin or a copolymer of these resins and a styrene resin.

The most suitable material for the magnetic particles used in the present invention is
98% or more Cu-Zn-Fe (composition ratio (5-20):
Ferrite particles having a composition of (5-20): (30-80)) can be easily smoothed on the surface, have a stable charge imparting ability, and can be coated stably.

The amount of the coating substance coated on the magnetic particles may be appropriately determined so that the charge imparting properties of the magnetic particles satisfy the above-mentioned conditions, but generally the total amount is 0.1 to 30% by weight (preferably 0.1 to 30% by weight based on the magnetic particles). is 0.3 to 20% by weight).

In addition, the weight average particle diameter of the stiff magnetic particles is 35 to 65 μm,
Preferably, it has a diameter of 40 to 60 μm. Furthermore, in the weight average particle size distribution, 26 μm or less is 2 to 6
%, and between 35 μm and 43 μm is 5% or more and 25%
A good image can be maintained when the diameter is below and the ratio of 74 μm or more is 2% or less.

The mixing ratio of the magnetic particles as described above and the negatively charged black toner particles of the present invention is usually 2.
Good results are obtained with 0-9% by weight, preferably 3-8% by weight. That is, if the toner concentration is less than 2.0% by weight, the image density will be too low to be practical, and if it is more than 9% by weight, fogging and in-machine scattering will increase and the useful life of the developer will be shortened.

In addition, in the present invention, fatty acid metal salts such as zinc stearate, aluminum stearate, etc., or fine powders of fluorine-containing polymers, such as polytetrafluoroethylene, polyvinylidene fluoride, etc., and tetrafluoroethylene-containing polymers are used as lubricants. A fine powder of vinylidene fluoride copolymer, an abrasive such as cerium oxide or silicon carbide, or a conductivity imparting agent such as tin oxide or zinc oxide may be added.

As a method for producing the colorant-containing resin particles used in the present invention, a thermoplastic resin as a binder resin is mixed with a pigment or dye as a colorant, a charge control agent, other additives, etc. by a ball mill or the like. After mixing thoroughly with a mixer,
Pigments or dyes are dispersed or dissolved in the resins by melting, mixing and kneading using a heat kneader such as a heating roll, a heat kneader, or an extruder, and then the pigment or dye is dispersed or dissolved in the mixture, which is cooled and solidified, and then pulverized and kneaded. Colorant-containing resin particles can be obtained by rigorous classification.

In the photodetection automatic toner concentration control device used in the present invention, the sensor window 13 may be made of any transparent material as long as it has the same polarity as the toner when charged with magnetic particles. Desirable from the point of view of energy and charging characteristics.

Examples of such fluorine-based resins include polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, halofluoropolymers such as polytrifluorochloroethylene, polytetrafluoroethylene, polyperfluoropropylene, and fluorinated resins. Copolymer of vinylidene and acrylic monomer, copolymer of vinylidene fluoride and trifluorochloroethylene, copolymer of tetrafluoroethylene and hexafluoropropylene, copolymer of vinylidene fluoride and vinylidene fluoride fluorocarbons such as copolymers of vinylidene fluoride and tetrafluoroethylene, copolymers of vinylidene fluoride and hexafluoropropylene, and terpolymers of tetrafluoroethylene and vinylidene fluoride and non-fluorinated monomers. Polymers and the like are preferably used.

Among these, polytetrafluoroethylene or a copolymer of polytetrafluoroethylene and polyvinylidene fluoride is preferred from the viewpoint of strength and charging characteristics.

A method for measuring the characteristic values of the toner used in the present invention will be described below.

Frictional charge measurement/ The measurement method will be explained in detail using drawings.

FIG. 2 is an explanatory diagram of an apparatus for measuring the amount of triboelectric charge of toner.

First, a mixture of an additive and a carrier whose weight ratio is 2:98, whose triboelectric charge amount is to be measured, is placed in a metal measurement container 2 with a 500-mesh screen 3 at the bottom.
Pour the mixture (developer) into a 4-capacity polyethylene bottle and shake by hand for about 10 to 40 seconds to make the mixture (developer) about 0.5 to 1.5
g and cover with metal lid 4. The weight of the entire measuring container 2 at this time is weighed and is defined as W+ (g).

Next, in the suction mechanism (at least the part in contact with the measurement container 2 is an insulator), suction is carried out from the suction lower and the air volume control valve 6
Adjust the pressure of the vacuum gauge 5 to 250 mmAq. In this state, suction is performed for a sufficient period, preferably 2 minutes, to remove the toner by suction. The potential of the electrometer 9 at this time is ■ (volt)
shall be. Here, 8 is a capacitor whose capacity is C(
μF). In addition, the weight of the entire measuring container after suction is weighed and is defined as W2 (g).

As a result, the amount of triboelectric charge (μc/g) of the toner is calculated as shown in the following formula.

(However, the measurement conditions are 23° C. and 60% RH.) (Example) Next, the present invention will be described in more detail with reference to Examples.

Note that the text in the middle of the text is based on weight unless otherwise specified.

After thoroughly premixing Example 1 (hereinafter referred to as the blank) using a Henschel mixer,
The mixture was melt-kneaded at least twice using a three-roll mill, and after cooling, it was coarsely ground using a hammer mill to a particle size of approximately 1 to 2 mm. Then, it was pulverized using an air jet type pulverizer.

Further, the obtained finely ground product was classified using a multi-division classifier to obtain colorant-containing resin particles having a volume average particle diameter of 8.3 μm.

The apparent viscosity of this particle is 6.0OX105 voids at 90°C and 1.0OX at 100°C. The voice was lXl0'.

To 100 parts of the above colorant-containing resin particles, 0.3 parts of alumina fine powder with a charge amount of -3 μc/g and a specific surface area of 10 Or#/g by the BET method, and a specific surface area of 250 r&/g by the BET method. A negatively chargeable black toner of the present invention was prepared by externally adding 0.5 part of silica fine powder having a charge amount of -80 μc/g that had been hydrophobized with hexamethyldisilazane.

The surface of 6 parts of this black toner was coated with styrene-methyl methacrylate-2-ethylhexyl acrylate copolymer (copolymerization ratio 50.20.30, weight average molecular weight 5.000, number average molecular weight 4.000). Cu-Zn-Fe
A developer was prepared by mixing 94 parts of ferrite particles (average particle size: 47 μm).

Next, a running test of 30,000 sheets was conducted using the above developer using polytetrafluoroethylene as the ATR window member of a commercially available W color copier (CLC-500, manufactured by Canon) at room temperature (23°C/23°C). 60%RH), low temperature and low humidity (2
0°C/10% RH) and high temperature (30°C/80%
It was performed in each environment of R1 ().

As a result, high-quality images with sufficient image density were obtained in any environment. At this time, the 1-ner concentration was within the range of 6±0.5% under any environment.

Comparative Example 1 In Example 1, when images were produced in the same manner as in Example 1 except that alumina fine powder was not used, there was a large fluctuation in image density under low temperature and low humidity, and image fogging was also different from that in Example 1. increased compared to

The variation in toner density at this time was 6-1.3% to 6005%.

Comparative Example 2 When image formation was carried out in the same manner as in Example 1 except that fine silica powder was not used, the fluidity of the developer was poor at room temperature and the toner concentration was 6±2%. Thick (
It has changed.

Comparative Example 3 A toner was prepared in the same manner as in Example 1, except that no charge control agent was used, and when images were printed, the toner was a source of density under low temperature and low humidity conditions, and toner scattering occurred under high temperature and high humidity conditions.

This means that there is a large environmental difference in charge amount compared to Example 1, and the charge control agent as adopted in Example 1 is an essential component in the negatively chargeable black toner of the present invention. This suggests something.

Comparative Example 4 When an image was produced in the same manner as in Example 1 except that the 'ATR window member was made of polymethyl methacrylate, the image density decreased under low temperature and low humidity. Ta.

Also, the variation in toner density at this time is 6-2.0 to 6+0.
It was 2%.

Example 2 The same procedure as in Example 1 was performed except that the ATR window member was made of a copolymer of polytetrafluoroethylene and polyvinylidene fluoride (5050).
Similar good results were obtained.

The variation in toner density at this time was 6-07% to 6+1%.

Example 3 Image formation was carried out in the same manner as in Example 1, except that the same compound (4 parts) represented by the following structural formula (2) was used instead of the charge control agent used in Example 1. When tested, the charging property was stable under any of the following environments: normal temperature, low temperature and low humidity, and high temperature and high humidity, and almost no fluctuation in image density was observed.

The toner concentration fluctuation during the 30,000-sheet durability was 6±0.5%.

Comparative Example 5 A black toner was produced and an image was produced in the same manner as in Example 3 except that 35 parts of carbon black was used instead of the three types of colorants in Example 3. The initial image was produced under low temperature and low humidity. Although it performed reasonably well in both the high-temperature, high-humidity environments, the toner density began to deviate significantly over the course of the test, and image production had to be interrupted midway through the test.

This means that the toner of this comparative example could not be applied to a developing system having an infrared reflective type photodetection automatic toner density control device.

(Effects) According to the present invention as described above, a negatively chargeable black toner having excellent charging characteristics and fluidity can be obtained.

As a result, when the negatively chargeable black toner of the present invention is applied to a two-component developer and an image is produced, it is possible to obtain an image with high density (and excellent fine line reproducibility and highlight gradation).

Furthermore, such developers are compatible with and can function satisfactorily in development devices having photo-sensing automatic toner concentration control devices.

Further, the negatively chargeable black toner of the present invention has a stable toner concentration even when used for a long time, and its performance does not change even with environmental changes.

Furthermore, high image density can be obtained with a small amount of colorant and toner consumption.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a photodetection automatic toner concentration detection section,
FIG. 2 is an explanatory diagram of the frictional charge amount measuring device. 10. Light source 11: First sensor 12: Second
Sensor 13/Sensor window member 14: Light source light
15.Developer reflected light patent applicant Canon Co., Ltd.

Claims (6)

[Claims] (1) Applied to a two-component developer containing at least nonmagnetic colorant-containing resin particles consisting of a charge control agent, two or more types of colorants, and a binder resin, and two or more types of inorganic oxides. In the black toner, the charge control agent is represented by the following general formula [I], one of the inorganic oxides has an absolute value of triboelectric charge with the magnetic particles of 50 μc/g or more, and the BET method is used. Specific surface area S_A is 80-300
m^2/g is a negatively charged hydrophobic inorganic oxide A, and the other inorganic oxide has an absolute value of triboelectric charge with the magnetic particles of 2.
A hydrophilic inorganic oxide B having a specific surface area S_B of 0 μc/g or less and a specific surface area S_B of 30 to 300 m^2/g by the BET method,
In addition, these inorganic oxides A and B contain A by weight % and B by b weight % with respect to the colorant-containing resin particles, respectively, and S_A≧S_B, a≧b, 0.3≦a+b
≦1.5, a negatively chargeable black toner whose density can be controlled by a photodetection automatic toner density control device having a photodetection section made of a transparent material. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] (In the formula, R_1 represents a halogen atom, R_2 represents a hydrogen atom, a nitro group, an alkyl group, an amino group, an alkylamino group, an alkoxy group, or an acetoxy group, and n is 0~
An integer of 3, m represents an integer of 1 to 4. Also, R_3, R
_4 represents a hydrogen atom, an alkyl group, an amino group, an alkylamino group, a carboxyl group, or ▲a mathematical formula, a chemical formula, a table, etc.▼, where X_1 is a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, or a halogen represents an atom, and l represents an integer of 1 to 2. M represents chromium, iron, aluminum or cobalt, A^■
represents a counter cation such as a hydrogen ion, sodium ion, potassium ion or ammonium ion. ) (2) Negative chargeability according to claim 1, wherein the binder resin is mainly composed of a polyester resin, the hydrophobic inorganic oxide A is a hydrophobic silica particle, and the hydrophilic inorganic oxide B is an alumina particle. black toner. (3) 3 in the near-infrared region, especially in the range of 900 to 1000 nm
The negatively chargeable black toner according to claim 1 or 2, having a spectral reflectance of 0% or more. (4) Toner concentration control, characterized in that the concentration of the negatively chargeable black toner according to any one of claims 1 to 3 is controlled using a photodetection automatic toner concentration control device having a photodetection section made of a transparent material. Method. (5) The toner concentration control method according to claim 4, wherein the transparent material is charged to the same polarity as the toner by frictional charging with the magnetic particles. (6) The toner concentration control method according to claim 4, wherein the transparent material is made of a fluororesin.