JP2866122B2 - Negatively chargeable color toner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negatively chargeable color toner for visualizing an electrostatic latent image in an image forming method such as electrophotography and electrostatic recording.

[Prior Art] In recent years, as image forming apparatuses such as color copying machines for electrophotography have become widespread, their uses have also been diversified and the demands for image quality have become strict. In copying an image such as a general catalog or a map, it is required to reproduce extremely finely and faithfully without being crushed or interrupted even in a minute portion.

Recently, in an image forming apparatus such as a color copying machine for electrophotography using digital image signals, a latent image is formed by collecting dots of a constant potential, and a solid portion, a halftone portion and a light portion are formed. Is expressed by changing the dot density. However, if the toner particles do not adhere to the dots and the toner particles protrude from the dots, the gradation of the toner image corresponding to the dot density ratio of the black portion and the white portion of the digital latent image cannot be obtained. There is a problem. Further, when the resolution is improved by reducing the dot size in order to improve the image quality, the reproducibility of the latent image formed from minute dots becomes more difficult, and the resolution and especially the gradation of the highlight part are increased. The image tends to be poor in quality and lacks in sharpness.

In view of the above problems, the present inventors have studied to reduce the particle size of the toner and to enhance the faithful reproducibility of a latent image composed of minute dots.

However, when the particle diameter of the toner is reduced, the cohesiveness of the toner itself is increased, which causes a problem that the mixing property with the carrier is reduced or the fluidity of the toner is reduced. As the diameter increases, the specific surface area of the toner increases, so that the amount of charge in contact charging with the carrier becomes excessive, causing new problems such as low density and poor transfer.

Today, in this research field, polyester resins are widely used as binders for color toners because of their high negative chargeability and excellent fixability.
Generally, resins such as polyester are susceptible to temperature and humidity during frictional electrification with the carrier, and are susceptible to problems such as excessive charge at low temperature and low humidity and insufficient charge at high temperature and high humidity. There is an urgent need to develop better toners.

As described above, when trying to further reduce the particle size of the toner, there are a number of problems encountered, among which the improvement of the charging characteristics is indispensable, and this is the most important item in toner development.

[Problems to be Solved by the Invention] An object of the present invention is to provide the following negatively chargeable color toner.

Performance is stable even for long-term use and environmental fluctuations.

Even in an image forming apparatus having a high image density and particularly using a digital image signal, an image excellent in resolution, highlight gradation and fine line reproducibility is formed.

Excellent transferability and high image density can be obtained with small consumption.

[Means and Actions for Solving the Problems] The present invention relates to a negative electrode containing at least a non-magnetic colorant-containing resin particle containing a colorant negative charge control agent and a polyester resin as a binder resin and an external additive. A chargeable color toner, wherein the polyester resin has the following formula: (Wherein R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 2)
It is 10. The negatively-chargeable color toner is a metal complex of an alkyl-substituted salicylic acid as the negative charge control agent. And containing at least a negatively-charged hydrophobic inorganic oxide A and alumina particles B as the external additive, wherein the negatively-charged hydrophobic inorganic oxide A has a specific surface area S _A by a BET method. There is a 80 m ² / g or more, the alumina particles B, the temperature / humidity = 15 ° C. / 10% saturation water content Q _L at 1.5 wt% or more,
The saturated water content at 32.5 ° C / 85% Q _H is 12% by weight or less,
_H, the ratio Q _H / Q _L ≦ 3 for Q _L, and the specific surface area by the BET method
S _B is 30~300m ² / g, a specific surface area S _B of the specific surface area S _A and the alumina particles B of the negative chargeable hydrophobic inorganic oxide A, and satisfies the following relationship S _A ≧ S _B The content of the negatively charged hydrophobic inorganic oxide A is a (% by weight) and the content of the alumina particles B is based on the colorant-containing resin particles.
Wherein the content a and the content b satisfy the following relationship: a ≧ b, 0.3 ≦ a + b ≦ 1.5, where b is the content of b (% by weight). About.

When a low-charge inorganic oxide such as alumina particles is externally added to the toner, it functions as a kind of spacer in frictional charging between the carrier and the toner, and as a result, forms a low-charge portion on the toner surface, and the charge amount of the toner. Suppress excessive. In addition, it has an effect of relatively lowering the negative property of the negatively chargeable polyester toner, which is useful for improving the charge characteristics. Therefore, when attempting to reduce the particle size of the toner, it is essential to use a low-charge inorganic oxide such as alumina particles.

Also, when the particle size of the toner is reduced, the Coulomb force and Van der Waals force acting on the toner become relatively stronger than the gravity and inertia force, so that the adhesive force between the toners becomes stronger, and toner aggregates are easily generated. In this case, the alumina particles function effectively to reduce the adhesion between the toners, thereby making it difficult to form toner aggregates.

Furthermore, in order to reduce direct contact between the toner base and the carrier surface, it is useful for toner spent on the carrier surface, and also achieves a longer life of the developer.

As described above, alumina particles are very effective in preventing aggregation of toner or suppressing excessive charging. However, in the present invention, it has also been found that there is a correlation between the water content of alumina particles and charging characteristics. As a result, the charging characteristics have been further improved.

That low temperature and low humidity (15 ° C., 10%) water content Q _L due to heat loss measurements of left alumina particles 10 days is not less 1.5% by weight or more, high temperature and high humidity (32.5 ° C., 85%) left in 10 days water content Q _H of the alumina particles is not more than 12% by weight and that
Q _H, the better charging properties when the ratio of Q _L was used externally added alumina grains satisfying Q _H / Q _L ≦ 3 in the colorant-containing resin particles obtained.

In the present invention, by adding alumina particles, (1) forming a portion having low chargeability on a so-called toner surface which is not in direct contact with the carrier by contact charging with the carrier; Since the particles have a weak positive property, they function to suppress the excessive charge amount especially at low temperature and low humidity due to the fact that the negative charge property is relatively weakened by adhering to the surface of the negatively charged polyester toner. However, in our study, in addition to the above (1) and (2), (3) the portion where the alumina particles are adsorbed on the toner surface becomes a kind of leak point, and the charge amount is excessively increased. We found the finding that it would be suppressed. In detail, a crystal defect site of the alumina particles used in the present invention or an adsorption site where water molecules are adsorbed or the like serves as a leak point, and functions to suppress excessive charging of electricity obtained by contact charging with the carrier. I do. In other words, it was considered that the higher the water content of the alumina particles used, the larger the active sites of the alumina particles, and the conclusion was that the above-described effects were greater.

Therefore, under low temperature and low humidity conditions (15 ° C., 10%), when alumina particles are externally added to the toner in order to reduce the charge of the toner, alumina particles having a high water content are more preferable. it is desirable moisture content Q _L in the left for 10 days is at least 1.5% by weight or more. If such surface area of the present invention use a little big alumina particles Q _L is there no particular problem is 1.5 wt% or more, but if Gotoki alumina particles having been subjected to hydrophobic treatment, Q _L is
If the amount is less than 1.5% by weight, charge-up occurs in a fine portion where the toner and the alumina particles are in contact with each other, and it is not possible to expect the tribodown as expected.

As described above, under low temperature and low humidity, alumina particles having a high water content are more advantageous for suppressing excessive charging of toner, but under high temperature and high humidity (32.5 ° C, 85%), conversely. The tribo drops too much, causing toner to scatter inside the machine,
Evils such as fog are likely to occur. Especially Q _H
If it exceeds 12% by weight, the triboelectricity is greatly reduced and toner scattering becomes severe. In addition, if Q _H > 12% by weight, the fluidity of the developer slightly deteriorates, and problems such as trouble during toner replenishment and poor mixing and agitation in the developing device easily occur. The water content of thus alumina particles Q _L is 1.5 wt% or more, and a Q _H is 12 wt% or less.

For example it is possible that can reduce scattering even alumina particles, such as exceeding Q _H is assumed 12% Reducing the amount of alumina particles added to the toner for the above such problems.
However, when trying to achieve tribo-down under low temperature and low humidity at the same time, reducing the amount of alumina particles is obviously in the direction of increasing tribo, and eventually it is impossible to obtain a balanced charging performance in both environments Would.

Therefore, in order to obtain a well-balanced charge in both environments, it has a certain water content under low temperature and low humidity, and functions positively to suppress the amount of charged electricity. Even if it is left under moisture, the water content does not change much (water is hardly adsorbed) and the tribo is not lowered extremely. We have Q _H , Q _L
The ratio of the case of using alumina particles satisfying that the Q _H / Q _L ≦ 3, found that the charging property of the toner becomes closer to the more stable direction.

That alumina particles if Q _H / Q _L is larger than 3 is not also have characteristics that easily adsorb water,
Therefore, there is a large difference in the water content under both environments, and the effect of lowering the triboelectricity by external addition of alumina becomes more remarkable under high temperature and high humidity, causing the problem that the difference in the amount of charged electricity between the two environments increases. Would.

As shown at the beginning, the binder used in the present invention is a polyester resin, which has a problem in that the amount of charged electricity is excessive under low temperature and low humidity, and the shortage of tribo under high temperature and high humidity is a problem.
By employing the Q _H / Q _L ≦ 3 consisting of alumina particles, was led to provide a more environmental stability toner.

As described above, alumina particles are very effective in preventing toner aggregation or suppressing excessive charging.
For reasons described below, BET specific surface area S _B is 30 m ² / g
(About 40 mμ) to 300 m ² / g (about 5 mμ), more preferably 80 m ² / g (about 25 mμ) to 150 m ² / g (about
15mμ).

For example, alumina particles having a BET specific surface area greater than 300 m ² / g have sufficient fluidity, but the disadvantage is that the toner tends to be easily deteriorated due to its hydrophilicity. Deterioration is caused by a large change in the amount of charge when copying is continued while toner consumption is low.
It appears as a phenomenon that the fluidity of the developer deteriorates.

Further, in the case of alumina particles having a BET specific surface area smaller than 30 m ² / g, it becomes difficult to obtain sufficient fluidity even when used in combination with another fluidity imparting agent. Further, the dispersion of the fluidity-imparting agent tends to be insufficient, and fogging occurs in an image.

Even in the range of 30 to 300 m ² / g, adverse effects are likely to occur unless used in combination with hydrophobic silica. In the range of 30 to 100 mm ² / g, the use of only alumina particles results in insufficient fluidity, so it is necessary to use it together with hydrophobic silica having a high fluidity-imparting effect. Furthermore, in the range of 100 to 300 m ² / g, since the surface of the colorant-containing fine particles can be uniformly covered, the use of only low-charged alumina particles tends to extremely reduce the charge amount. . Therefore, it is necessary to use in combination with negatively charged hydrophobic silica.

As described above, the hydrophobic silica functions to supplement the low-charge inorganic oxide in terms of negative chargeability and fluidity-imparting ability. Therefore, if the BET specific surface area is not less than 80 m ² / g, sufficient function cannot be obtained. More preferably, it is 150 m ² / g or more.

Further, when the alumina particles and the hydrophobic inorganic oxide are used in combination, the fluidity of the toner is improved, and the mixing property of the developer, the toner cleaning property, and the like are improved as compared with the case where each is used alone.

To more effectively present invention are S _A ≧ S _B when the specific surface area of the hydrophobic inorganic oxide A S _A, a specific surface area of the alumina particles B was S _B, colored A and B It is necessary to add a weight% and b weight% a ≧ b and 0.3 ≦ a + b ≦ 1.5 to the agent-containing resin particles so as to satisfy the following formulas.

When a <b or (a + b) is out of the above range, it is difficult to balance the chargeability and the fluidity.

Further, when (a + b)> 1.5, the fixing characteristics as a color toner are reduced, and in particular, the transparency of a trapene is reduced.

The hydrophobic inorganic oxide used in the present invention has a specific surface area of 80 m ² / g or more, and the absolute value of the triboelectric charge amount with the magnetic particles is 50 μc / g or more. Although it does not matter, a preferred example is a treated silica fine powder obtained by subjecting a silica fine powder generated by gas phase oxidation of a silicon halide compound to a hydrophobic treatment. It is particularly preferable that the treated silica fine powder is obtained by treating the silica fine powder such that the degree of hydrophobicity measured by a methanol titration test shows a value in the range of 30 to 80.

Hydrophobization is applied by reacting with silica fine powder or chemically treating it with an organic silicon compound that physically adsorbs.

As a preferred method, silica fine powder produced by vapor phase oxidation of a silicon halide is treated with an organosilicon compound.

Examples of such organosilicon compounds are hexamethyldisilazane, trimethylsilane, trimethylchlorosilane,
Trimethylethoxysilane, dimethyldichlorosilane,
Methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α
-Chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane,
Triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane,
Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule with terminal positions For example, dimethylpolysiloxane containing a hydroxyl group bonded to one Si unit may be used for each unit. These are used in one kind or in a mixture of two or more kinds.

The treated silica fine powder preferably has a particle size in the range of 0.003 to 0.1 μm. Commercial products include Taranox-500 (Talco), Aerosil (AER
OSIL) R-972 (Nippon Aerosil).

On the other hand, the production method and crystal structure of the alumina particles are not particularly limited, but generally the alumina particles obtained by the gas phase method have a sharp particle size distribution, and the particle size can be controlled relatively easily. And the dispersibility on the toner surface is good. Also, even in the case of alumina particles obtained by a wet method, the specific surface area is 30 to 300 mm ² / g, preferably 80 to
It does not matter if the water content is 150 m ² / g and the water content is within the above-mentioned range.

The widespread processes for producing high-purity alumina by the so-called wet method include the thermal decomposition of ammonium alum, the hydrolysis of organic ammonium, the ethylene chlorohydrin method, the spark discharge method in water, and the heat treatment of ammonium aluminum carbonate. Although various methods such as decomposition methods have been put into practical use, even if alumina particles have the same chemical structure due to differences in starting material firing temperature, time, etc., the properties vary greatly from manufacturer to manufacturer. Regarding the morphology, primary particle diameter, and the like, differences due to differences in production methods are extremely likely to occur.

The alumina particles used in the present invention are preferably those that are not aggregated or those that are easily loosened even if they are aggregated. In the case of alumina particles that contain so-called "dama" that is strongly aggregated, they are uniformly dispersed on the toner surface. This is not preferable because it is difficult to perform the charging and the charge stability between the toners is lacking. It is also not preferable that the particles have an extremely square shape or a needle shape.

The purity of the alumina particles used in the present invention is not particularly limited as long as they are fine and uniform, and there is no problem as long as the particles are generally called high-purity alumina.

Alumina particles are amorphous because of their crystal structure.
Although many types such as α, γ, η, ζ, and σ types are known, there is no particular limitation as long as the specific surface area by the BET method is in the range of 30 to 300 m ² / g. However, so-called α-type alumina, which is generally called alumina, has a small surface area and a relatively large particle size, and therefore, it is preferable to use an intermediate alumina having a small particle size such as a γ-type alumina.

Alumina is obtained by sintering aluminum hydroxide or an aluminum salt, but it is said that the alumina goes through various processes depending on the difference of starting materials and sintering conditions, and finally becomes α-type alumina. Therefore, aluminas other than α-type are called intermediate aluminas or transition aluminas.Intermediate aluminas such as γ-types have a characteristic that the crystal structure is unstable and the surface area is high, so that water is easily taken in. I have.

As described above, the alumina used in the present invention has a greater effect of lowering the triboelectricity as the water content increases, and under low temperature and low humidity, alumina having a high water content is preferable, and the alumina has a high activity. In this case, it can be said that the γ-type functions more effectively than the α-type.

However, even in the case of α-type alumina, if the particle size is extremely reduced through some kind of crushing process, the dispersibility on the toner surface increases, and as a result, it functions to suppress an excessive charge amount. Therefore, in the present invention, α
-It does not specify the existence ratio or the mixing ratio of alumina and γ-alumina at all.

For alumina and the like having particularly high water content under high temperature and high humidity, the surface may be subjected to some kind of hydrophobic treatment.

As the binder resin used for the colorant-containing resin particles of the present invention, first, a polyester resin is required.

Polyester resins have excellent fixability and are suitable for color toners.On the other hand, they have strong negative charging ability and tend to be excessively charged. Thus, a neutral color toner is obtained.

In particular, the following equation used in the present invention (Wherein R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2
~ 10. ), And a polycarboxylic acid composed of a di- or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid) An acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) are more preferable because they have a sharp melting property.

In particular, from the viewpoint of light transmission with a trapene, the apparent viscosity at 90 ° C. is 5 × 10 ^{4 to} 5 × 10 ⁶ poise, preferably 7.5 × 10 ⁴ poise.
２2 × 10 ⁶ poise, more preferably 10 ⁵ to 10 ⁶ poise, and the apparent viscosity at 100 ° C. is 10 ^{4 to} 5 × 10 ⁵ poise, preferably 10 ^{4 to} 3 × 10 ⁵ poise, more preferably 10 ⁴ to 2
Color O with good light transmittance due to × 10 ⁵ poise
As a result, good results can be obtained in fixing property, color mixing property and high-temperature offset resistance as a full-color toner. Especially
The absolute value of the difference between the apparent viscosity P ₂ at apparent viscosity P ₁ and 100 ° C. at 90 ° C. is, 2 × 10 ⁵ <| particularly preferably in the range of ^{_{<4 × 10 6 | P 1}} -P 2 .

As the coloring agent used in the present invention, known dyes and pigments such as copper phthalocyanine, insoluble azo, disazo yellow,
Anthraquinone pigments, quinacridone pigments, disazo oil-soluble dyes, and the like can be widely used.

A colorant that has been subjected to some surface treatment for the purpose of increasing the affinity between the resin and the colorant may be used.

Particularly preferred pigments include CI Pigment Yellow
17, CI Pigment Yellow 1, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Red 5, CI Pigment Red 2, CI Pigment Red 3, CI Pigment Red 1
7, CI Pigment Red 22, CI Pigment Red 2
3, CI Pigment Red 122, CI Pigment Blue 1
5, CI Pigment Blue 16 or imidoalkyl group [for example, (Wherein R represents an alkylene group having 1 to 5 carbon atoms)] as a substituent, a copper phthalocyanine-based pigment having one or a plurality thereof, or a structural formula (I) shown below,
And copper phthalocyanine pigments which are Ba salts in which two or three carboxybenzamide methyl groups are substituted on the phthalocyanine skeleton.

Examples of the dye include CI Solvent Red 49, CI Solvent Red 52, and CI Solvent Red 109.

As for the content, for the yellow toner which is sensitive to the transparency of the OHP film, the binder resin 100
8 parts by weight or less with respect to parts by weight, preferably 0.5 to
6 parts by weight is desirable.

When the amount is more than 8 parts by weight, the reproducibility of green, red, which is a mixed color of yellow, and an image of human skin color is inferior.

For other magenta and cyan color toners, the amount is preferably 10 parts by weight or less, more preferably 0.1 to 8 parts by weight, based on 100 parts by weight of the binder resin.

In the negatively chargeable color toner of the present invention, a metal complex of an alkyl-substituted salicylic acid (for example, a chromium complex or a zinc complex of di-tert-butylsalicylic acid) is used as a negative charge control agent. Since the negatively charged characteristics can be stabilized, and the metal complex of the alkyl-substituted salicylic acid is colorless or pale,
It is preferable because it does not affect the color tone of the color toner.

In the negatively chargeable color toner of the present invention, the metal complex of the alkyl-substituted salicylic acid is added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the binder resin.

As the magnetic particles used in the present invention, for example, metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earth and the like, and their alloys, oxides, and ferrites which are not oxidized or surface oxidized can be used. Also, there is no particular restriction on the manufacturing method.

In the present invention, the surface of the magnetic particles is coated with a resin or the like.A method of dissolving or suspending a coating material such as a resin in a solvent and applying the coating material to adhere to the magnetic particles, or simply a powder method Any of the conventionally known methods, such as a method of mixing with, can be applied. 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, for example, amino acrylate resin,
Acrylic resins or copolymers of these resins and styrene resins, silicone resins, polyester resins, polytetrafluoroethylene, monochlorotrifluoroethylene polymers, polyvinylidene fluoride, etc. are preferred, but not necessarily Not restricted.

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

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

The amount of the compound to be coated may be appropriately determined so that the charge imparting property of the magnetic particles satisfies the above-described conditions, but is generally 0.1 to 30% by weight (preferably 0.3 to 30% by weight) based on the magnetic particles of the present invention. 20% by weight).

These magnetic particles preferably have a weight average particle size of 35 to 65 μm, preferably 40 to 60 μm. Furthermore, 2 to 6% is the weight distribution of 26 μm or less, and the weight distribution is 35 μm or less.
A good image can be maintained when the distance between 43 μm is 5% or more and 25% or less and when the distance between 74 μm or more is 2% or less.

In the present invention, the mixing ratio between the magnetic particles and the color toner is 2.0% by weight to 9% by weight as the toner concentration in the developer.
%, Preferably 3% to 8% by weight usually gives good results. When the toner concentration is less than 2.0% by weight, the image density is low and cannot be used practically. When the toner concentration is more than 9% by weight, fog and scattering in the machine are increased, and the useful life of the developer is shortened.

Further, in the present invention, a fatty acid metal salt as a lubricant,
For example, zinc stearate, aluminum stearate, or
The fine powder region of the fluorine-containing polymer, for example, polytetrafluoroethylene, polyvinylidene fluoride, etc. and the fine powder region of the tetrafluoroethylene-vinylidene fluoride copolymer may be an abrasive such as cerium oxide or silicon carbide, or tin oxide. And a conductivity-imparting agent such as zinc oxide.

In order to produce the colorant-containing resin particles according to the present invention, a thermoplastic resin, if necessary, a pigment or dye as a colorant, a charge control agent, and other additives are sufficiently mixed by a mixer such as a ball mill. Heating roll, kneader,
Using a hot kneader such as an extruder, melt or knead and knead the resin to disperse or disperse the pigments or dyes in the resin, and then pulverize and strictly classify after cooling and solidifying. The colorant-containing resin particles according to the present invention can be obtained.

Hereinafter, each of the measurement methods (1) to (3) relating to the characteristic values of the developer used in the present invention will be described.

(1) Particle size distribution measurement: Coulter counter TA-II type (manufactured by Coulter, Inc.) was used as a measuring device, and an interface (manufactured by Nikkaki) for outputting a number average distribution and a volume average distribution, and a CX-1 personal computer (manufactured by Canon) ) And the electrolyte is 1
Prepare a 1% aqueous NaCl solution using graded sodium chloride.

As a measuring method, a surfactant as a dispersing agent, preferably 0.1 to 5 ml of an alkylbenzene sulfonate is added to the electrolytic aqueous solution of 100 to 150 ml, and a measurement sample of 0.5 to 50 mg is further added.
Add.

The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and the solution was applied to the solution using the Coulter Counter TA-II using a 100 μm aperture as an aperture.
The volume average distribution and the number average distribution are obtained by measuring the particle size distribution of the particles of up to 40 μm.

From the obtained volume average distribution and number average distribution, values of the volume average particle diameter and the number average distribution of 6.35 μm or less and the volume average distribution of 16.0 μm or more are obtained.

(2) Measurement of triboelectric charge: FIG. 1 is an explanatory view of a triboelectric charge measuring device. First, a mixture of particles to be measured and magnetic particles used as a developer is prepared. The mixing ratio is 5 parts by weight for 95 parts by weight of magnetic particles in the case of toner and colorant-containing fine particles, and 2 parts by weight in 98 parts by weight of magnetic particles in the case of a fluidity imparting agent. .

The magnetic particles used in the measurement are the magnetic particles used in the two-component developer. For example, ferrite particles coated with a styrene resin, particles of 250 mesh pass 400 mesh on 70% by weight or more (more preferably 75 to
95% by weight) and coated with 0.2 to 0.7% by weight of a styrene-2-ethylhexyl acrylate-methyl methacrylate copolymer.

Measure the particles and magnetic particles to be measured in the measurement environment (23
(60 ° C, 60%), leave it for 12 hours or more, put it in a polyethylene bottle, mix well, and stir (reciprocate 150 times).

When the sample is colored resin powder, a mixture of 5 g of colored resin powder and 95 g of magnetic particles is used. When the sample is a flow improver, a mixture of 2 g of the flow improver and 98 g of magnetic particles is used. A polyethylene bottle having a volume of 100 ml is used, and a turbine mixer (3 times /
Second).

Next, the particles whose triboelectric charge is to be measured are placed in a metal measuring container 112 having a conductive screen 113 of 500 mesh (which can be changed to a size that does not allow magnetic particles to pass through) at the bottom shown in FIG. And a metal lid with a mixture of magnetic particles
Do 114. At this time, the weight of the entire measurement container 112 is weighed w ₁
(G). Next, in the suction device 111 (at least a portion in contact with the measurement container 112 is at least an insulator), the pressure of the vacuum gauge 115 is adjusted to 250 mmA by adjusting the air volume control valve 116 by suctioning from the suction port 117.
q. In this state, suction is sufficiently performed (about 2 minutes) to remove toner by suction. The potential of the electrometer 119 at this time is V
(Volts). Here, reference numeral 118 denotes a capacitor having a capacity of C (μF). Further, the weight of the whole measurement container after suction is weighed to be W ₂ (g). This triboelectric charge T (μc / g)
Is calculated as follows:

(3) Measurement of Water Content The measurement of the water content of the alumina particles was carried out by a generally known heat drying weight measurement method. Using an electronic moisture meter PD ₂ -300WMB as measuring device, the set temperature 0.99 ° C. at a water content timer measurement mode was conducted at 10 minutes of drying conditions.

Low temperature and low humidity (15 ℃, 10%), high temperature and high humidity (32.5 ℃, 85%
%), Weigh about 2 g of a flat weighing bottle (inner diameter 50 mm) with a known weight, spread it out so that the sample becomes almost uniform in thickness, and clean the weighing bottle containing the sample. Weigh. After heating and drying at a set temperature of 150 ° C. for 10 minutes, the weight is weighed to determine the weight loss, and the water content (% by weight) is calculated by the following equation.

Water content = (weight loss (g) / sample (g)) x 100 In this study, alumina particles were added to each environment for 1 day, 3 days, 5 days, and 10 days to determine the saturated water content under each environment. It was left standing and the number of days left until the water content reached saturation was examined. As a result, it was confirmed that there was almost no difference in water content between the product left for 3 days and the product left for 5 days, and the value hardly fluctuated even after 10 days. Therefore, in each environment 10
It was assumed that the sample had reached the saturated water content after being left for a day, and the saturated water content was defined as the combined water content of the environmentally left products for 10 days.

In addition, in this study, the water content Q _H
There are also confirmed that the show always a value greater than if the amount of water Q _L of the low-temperature and low-humidity under standing goods.

Q _L <Q _H [Example] The basic configuration and features of the present invention have been described above, and the method of the present invention will be specifically described below based on the examples. However, these do not limit the embodiments of the present invention at all. All parts in the examples are parts by weight.

Example 1 Was thoroughly mixed by a Henschel mixer, melt-kneaded twice with a three-roll mill, cooled, and coarsely ground to a particle size of about 1 to 2 mm using a hammer mill. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified by a multi-segment classification device to obtain colorant-containing resin particles.

The water content of the alumina particles was measured at a low temperature and low humidity (15 ° C., 10%) in 100 parts of the colorant-containing resin particles by a heating loss measurement method.
In standing 0 day Q _L is 3.1%, the high temperature and high humidity (32.5 ° C., 85
%) Water content Q _H standing for 10 days is 5.8%, the alumina particles having a specific surface area by BET method was obtained by the gas phase method is 96m ₂ / g (charge -2μc / g) 0.3 parts of the BET method The toner had a specific surface area of 250 m ₂ / g, and 0.5 part of silica fine powder (charge amount -80 μc / g) hydrophobized with hexamethyldisilazane was externally added to obtain a cyan toner.

Styrene-acrylic acid-
Cu coated with methacrylic 2-ethylhexyl copolymer
A developer was prepared by mixing 94 parts of -Zn-Fe-based ferrite particles.

Table 2 shows the charge of the toner in a low-temperature and low-humidity environment (15 ° C., 10% RH) and the charge in a high-temperature and high-humidity environment (32.5 ° C., 85% RH).

Using this developer, a commercially available plain paper color copier (CLC
-500 Canon), a running test of 30,000 sheets was conducted in each environment of normal temperature and normal humidity (23 ° C, 60%), low temperature and low humidity (15 ° C, 10%), and high temperature and high humidity (32.5 ° C, 85%). As a result, a high-quality image having a sufficient image density was obtained in any environment.

Example 2 Alumina particles obtained by the wet method in Example 1 (Q _L = 4.5, Q _H = 6.1%, specific surface area by BET method was 126 m ₂ /
g, charge amount 0 μc / g) When images were produced in the same manner except that 0.3 parts were used, sufficient image density and high quality images were obtained even under low temperature and low humidity, and under high temperature and high humidity. A sharp image without fog was obtained.

Comparative Example 1 The same extraction was performed except that 0.3 parts of alumina particles (specific surface area of 146 m ₂ / g by BET) with Q _L = 3.6% and Q _H = 11.5% in Example 1 were used, and alumina particles were added. The effect of the suppression of the excessive amount of charged electricity due to is more remarkable under high temperature and high humidity. Under low temperature and low humidity, the same image density and high quality image as in Example 1 were obtained. The scattering of the toner accompanying it was noticeable.

Comparative Example 2 A cyan toner was prepared in the same manner as in Example 1 except that the alumina particles used in Example 1 were doubled from 0.3 part to 0.6 part. Under high temperature and high humidity, toner scattering became remarkable.

Comparative Example 3 An image was formed in the same manner as in Example 1 except that no alumina particles were added. Under low temperature and low humidity, particularly, the charged amount was high, and a poor image having a low image density was obtained.

In the case of using a toner having a small particle diameter as in the present invention, an external additive such as alumina particles which functions to suppress an excessive charge amount is indispensable.

Example 3 Magenta resin particles were obtained in the same manner as in Example 1 except that 4.5 parts of CI Pigment Red 122 was used.

Q _L = 4.5% in 100 parts of this colorant-containing resin particles, Q _H = 6.1
% Alumina particles (specific surface area by BET method is 126 m ₂ /
g, charge amount: 0 μc / g) 0.2 parts of the silica fine powder used in Example 1 were externally added to obtain a magenta toner. Five parts of the magenta toner were mixed with 95 parts of the coat carrier used in Example 1 to obtain a developer, which was similarly used for 30,000 sheets. Even at 30,000 sheets of durability, a stable image and a high quality image were always obtained without a large change in density.

[Effects of the Invention] As described above, according to the present invention, a high-quality image can be stably provided for a long period of time in any environment.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an apparatus for measuring a triboelectric charge amount in the present invention.

Claims (2)

(57) [Claims] 1. A negatively chargeable color toner containing at least a non-magnetic colorant-containing resin particle containing a colorant, a negative charge control agent, and a polyester resin as a binder resin, and an external additive, The polyester resin has the following formula (Wherein R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2
~ 10. Wherein the diol component having a bisphenol derivative or a substituent and a polycarboxylic acid component are synthesized by cocondensation, and the negatively chargeable color toner is a metal of an alkyl-substituted salicylic acid as the negative charge control agent. A complex, containing at least a negatively-charged hydrophobic inorganic oxide A and alumina particles B as the external additive, wherein the negatively-charged hydrophobic inorganic oxide A has a specific surface area S by a BET method. _A is 80 m ² / g or more, and the alumina particles B have a temperature /
Humidity = 15 ° C. / at 10% saturation water content Q _L is 1.5 wt% or more, 3
Saturated water content Q _H at 2.5 ° C. / 85% is not more than 12% by weight,
Q _H, the ratio Q _H / Q _L ≦ 3 for Q _L, and specific surface area by the BET method: S _B is 30~300m ² / g, the specific surface area S _A of the negative chargeable hydrophobic inorganic oxide A and the specific surface area S _B of the alumina particles B, and satisfies the following relationship S _a ≧ S _B, to colorant-containing resin particles, a content of the negative chargeable hydrophobic inorganic oxide a (% By weight) and the content of the alumina particles B is defined as b (% by weight), the content a and the content b satisfy the following relationship: a ≧ b, 0.3 ≦ a + b ≦ 1.5 A negatively chargeable color toner characterized by the following. 2. The negatively charged hydrophobic inorganic oxide A has an absolute value of a triboelectric charge with magnetic particles of 50 μc / g or more, and the alumina particles B have an absolute triboelectric charge with magnetic particles. Value is 20
2. The negatively chargeable color toner according to claim 1, wherein the color toner is not more than μc / g.