JPS63128364A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To improve triboelectrification characteristics by regulating the triboelectrifiable quantity of one of colorants to + or -10muC/g on the basis of that of the other colorant. CONSTITUTION:A toner contains as essential components a binder resin and the >=2 kinds of colorants in a prescribed relating to one another. On the basis of one of the colorants, the triboelectrifiable quantity of the other colorants are controlled in the range of + or -10C/g, that is, the >=2 kinds of colorants are expressed as A1, A2, ..., An (n>=2), the triboelectrifiable quantities of said colorants are expressed as T1, T2, ..., Tn, (T1<=T2<=...<=Tn, including the cases of positive and negative values), and an optional one of said quantities is expressed as Tk (1<k<n) is used as the basis, and all the triboelectrifiable quantities of the other colorants T1, T2, ..., Tk-1, Tk+1, ..., Tn, are regulated in the range of + or -10muC/g, preferably, + or -8muC/g of Tk.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to toners for electrophotography, and particularly to toners that exhibit a chromatic or black color depending on a combination of colorants.

Background Art Conventionally, in electrophotography, US Pat. No. 2297
691, Special Publication No. 42-23910, Special Publication No. 43
As described in Japanese Patent No. 24748, electrostatic charge is applied to the photoconductive layer by corona discharge, and a light image corresponding to the original is exposed to the photoconductive layer, thereby eliminating the charge in the exposed area and causing the latent Image formation is carried out, and further development is carried out by allowing a fine powder electrostatic substance, so-called toner, to adhere to the electrostatic latent image thus obtained. At this time, the toner is attracted to the electrostatic latent image depending on the amount of charge on the photoconductive layer, forming a toner image with shading. This toner image is transferred to the surface of a support such as paper or cloth as necessary, heated,
It is permanently fixed on the surface of the support by a suitable fixing means such as pressure, solvent treatment, top coating treatment, etc. Alternatively, if it is desired to omit the toner image transfer step, the toner image can be fixed onto the photoconductive layer.

On the other hand, many developing methods using developers such as the above toners are known, including the cascade development method described in U.S. Pat. No. 2,618,552, the magnetic brush method described in U.S. Pat. No. 2,874,063, and the touchdown method described in U.S. Pat. No. 2,895,847. There are other methods such as jumping development method. In particular, a magnetic brush method is known as a typical developing method, and in the magnetic brush method, magnetic particles such as steel or ferrite are used as carriers. A developer consisting of toner and this magnetic carrier is held by a magnet,
The magnetic field of this magnet arranges the developer in a brush shape. When this magnetic brush comes into contact with the electrostatic latent image surface on the photoconductive layer, only the toner is attracted from the brush to the electrostatic latent image.
Development is performed.

In addition, the jumping development method is a method in which DC and AC electric fields are simultaneously applied between an electrostatic latent image surface and a developer carrier to cause the developer to move back and forth between the latent image surface and the developer carrier. By doing so, development is performed.

These development methods can be used not only to obtain conventional black and white copies, but also to obtain multicolor copies. That is,
First, light from an original is exposed onto the photoconductive layer through a blue filter, and the electrostatic latent image formed is developed with yellow toner, which has a complementary color to that of the filter. Then, similarly, the latent images formed by exposure through a green filter and a red filter in alignment with the latent image are developed with magenta toner and cyan toner, respectively. Finally, "inking" is performed using black toner.

The developed four color toners are sequentially transferred to the same support, and a final color copy is obtained with one fixation. In this color development method, the order of development is not limited to the above-mentioned order of yellow, magenta, cyan, and black, and can be changed as appropriate.

In these color toners, several colorants are usually used in combination in order to obtain a desired color tone.

In this case, these colorants not only have the function of simply forming a color, but also have a wide range of effects on the charging function, environmental dependence, durability, etc. of the toner.

In particular, when attempting to obtain a black toner by combining colorants having a tone other than black, at least two types, and generally three or more types (from the concept of three primary colors), are used. There is a need. In such a case, finding a combination of colorants that provides good color tone and excellent electrophotographic properties while maintaining the desirable properties of the electrophotographic toner described above is important in determining the toner binding that actually uses these colorants. This was not an easy task because it was difficult to predict what kind of electrophotographic properties would be exhibited when it was included in a resin.

Therefore, conventionally, when attempting to obtain a chromatic or black toner by combining two or more types of colorants, a newly synthesized colorant or a large number of dyes and pigments existing on the market are appropriately combined. At present, colorant combinations that provide desirable toner characteristics have been searched and studied (by trial and error) by actually dispersing them in a binder resin to form a toner.

With such a development method, the probability of obtaining a toner having desirable properties is extremely low. In fact, conventionally known colorants for electrophotographic toners (
When actually incorporated into a toner binder resin to form a toner, the combination (combination of) not only has spectroscopic properties such as color tone, but also has sufficient electrophotographic properties such as charging properties, environmental stability, and durability. It wasn't satisfying.

OBJECTS OF THE INVENTION An object of the present invention is to provide an electrophotographic toner with good charging characteristics.

Still another object is to provide an electrophotographic toner which has good environmental stability and has a small difference in charge amount even under low temperature, low humidity and high temperature and high temperature environments.

Still another object is to provide an electrophotographic toner in which a colorant is well dispersed in a binder resin.

Still another object is to provide an electrophotographic toner that is resistant to carrier spent (carrier contamination) and has excellent durability.

Still another object is to provide an electrophotographic toner with good storage stability.

11Wataru11 The inventors discovered that when incorporated into toner binder resin,
After intensive study on combinations of colorants that provide excellent electrophotographic properties, we found that the mutual relationship of the charging characteristics among the colorants to be combined is the (apparent) compatibility of these colorants as a whole with respect to the toner binder resin. It was discovered that the solubility and affinity of these colorants are greatly affected, and furthermore, that there is a certain relationship between the amount of triboelectric charge of each of these multiple colorants. found it to be essential.

The toner for electrophotography of the present invention is based on the above knowledge, and more specifically, the toner for electrophotography of the present invention is based on the above knowledge, and more specifically, a binder resin, 2f! A toner comprising the above colorants; based on the triboelectric charge amount of any one of the colorants, the triboelectric charge amount of other colorants is within the range of ±10 μc/g. It is characterized by this.

The reason why the above effects are achieved in the toner of the present invention having the above configuration is not necessarily clear, but according to the findings of the present inventors, it is presumed as follows.

In other words, when two types of colorants are combined in a conventional toner (colorants with a difference in triboelectric charge amount of more than 10 μc/g), the colorants are attracted to each other and repulsed by each other, causing the particles to form in the binder resin. Due to uneven distribution and poor dispersion of these colorants, the overall compatibility or affinity of these colorants with the binder resin decreases, resulting in exposure of the colorant to the toner surface or separation of the colorant from the toner particles. It is estimated that this occurred.

On the surface of such conventional toner particles, colorant particles with (apparently) opposite charge polarity are exposed at the same time, and when the toners are charged by friction with each other or between the toner and the carrier, they exhibit negative properties. This results in a mixture of toner and positive toner. Therefore, when conventional toners are used, problems such as so-called fog, where toner of opposite polarity adheres to non-image areas, image defects such as a decrease in image density during continuous copying, and a decrease in environmental stability occur. It is estimated that

Furthermore, in conventional toners, the separation of the colorant from the toner particles as described above is thought to have caused so-called spent formation in which the colorant is fused to the carrier, a change in color tone, and the like.

On the other hand, in the toner of the present invention, a combination of two or more colorants whose triboelectric charge is within the range of ±10 μc/g shows good affinity with each other, and the colorants are uniformly contained in the binder resin. In addition, because it is well dispersed, the exposure of the colorant particles to the toner surface and the separation of the colorant from the toner particles are effectively suppressed, resulting in not only excellent charging characteristics and environmental stability, but also durability and It is estimated that the toner has excellent storage stability.

The present invention will be explained in more detail below. In the following description, "1 part" and "%" expressing quantitative ratios are based on weight unless otherwise specified.

Specific Films of the Invention The toner of the present invention contains as essential constituents a binder resin and two or more types of colorants that have a certain relationship in triboelectric charge amount.

In the above two or more colorants, the triboelectric charge amount of any one of these colorants must be within the range of ±10 μc/g based on the triboelectric charge amount of the other colorant. It is.

That is, the above two or more colorants are AI, A2...
An (n≧2), and the amount of triboelectric charge (including positive and negative signs) of each of these colorants is T 1 , T2 ,
"・, Tn (Tt≦T2≦...≦Tn). In this case, in the present invention, the value T of any one of these charge amounts (1≦≦n) is set as a reference. , this T is ±10 μc/g (more preferably ±8.0 μc
/g), the charge amount of other colorants (T1,...
, T K-+ and TK++, . . . , Tn). Here, the above r±10μc/g
"Within the range of +10μc/g or -10μ
It is used to include cases where it is equal to c/g.

In the present invention, it is sufficient to have at least one TK that satisfies the above conditions (which serves as a reference), but it is more preferable to have two or more such TKs.

Each coloring agent described above must have the same triboelectric polarity (for example, with respect to iron powder) (i.e., T1, T2, .
..., To have the same sign of plus or minus) is most preferable, but even if a colorant of opposite polarity is included, as long as the above-mentioned condition of ±10 μc/g is satisfied, it is practically acceptable. I can't help it.

If there is no TK that satisfies the conditions described above, that is, the amount of charge of (one of) the other colorants is ±10μc based on any TK (1≦ to ≦n).
If the ratio exceeds the range of /g, the mutual charge of the colorants will affect each other, and a large number of individual toner particles will be charged with opposite polarity, resulting in increased fog on images.

In addition, due to the attraction and repulsion of colorants, in the binder resin,
Uneven distribution and poor dispersion of these colorants occur, resulting in a decrease in image density from the initial stage and a spent state in the carrier during durability.

In the present invention, the amount of triboelectric charge (Tz
~Tn) is a value obtained by measuring the amount of charge on the iron powder carrier by a blow-off method.

More specifically, it is preferable to measure the amount of charge as described below. That is, first, the amount of charge should be measured.To 1.0 g of colorant, 9.0 g of 200/300 mesh iron powder carrier was added, and the mixture was thoroughly shaken and mixed (
For example, using a test sample that has been shaken for 1.0 minutes using a tarpaulin mixer, this test sample is applied to a triboelectric charge amount measuring device as shown in a schematic perspective view in FIG. 1 for measurement.

Referring to Figure 1, let's measure the amount of triboelectric charge in a metal measuring container 2 equipped with a conductive screen 1 of 400 mesh (the size can be changed as appropriate to prevent iron powder particles from passing through) on the bottom. Add about 0.5 g of the above test sample and cover with the metal lid 3. The weight of the entire measurement container 2 (including the lid 3) is accurately weighed and determined as wl (g). Next, using the suction device 4 (at least the part in contact with the measurement container 2 is made of an insulator), suction is drawn from the suction port 5, and the air volume control valve 6 is adjusted to bring the pressure shown on the vacuum gauge 7 to 70 m
+nHg.

In this state, suction is applied sufficiently (for about 1 minute) to remove the colorant. Directly read the potential of the electrometer 8 at this time, and
bolt).

Here, 9 is a capacitor, and this capacitance is C (μF)
shall be. Also, weigh the entire measurement container 2 after suction,
Let it be W2 (g). In this case, the triboelectric charge amount T(
μc/g) is determined by the following formula.

In the present invention, as the two or more colorants to be contained in the binder resin, a combination of colorants that satisfies the above-mentioned condition of ±10 tt C/g is selected, taking into consideration the spectral characteristics such as color tone. These colorants may be selected and used as appropriate, and known dyes and pigments may be used without particular limitation.
It can be used as is. A combination of dyes and pigments may be used if necessary.

As the dye, for example, C,1, Direct Red 1
, c, i, Direct Red 4, C1, Acid Red 1. C, 1, Basic Red 1, C,! , Mordaunt Red 30. C1, Solvent Red 49.
C,1, Solvent Red 52, c,r, Direct Blue 1, c,r, Direct Blue 2, C,1,
7 acid blue 9, C, 1, acid blue 15,
C, 1, Basic Blue 3, C, 1, Basic
Blue 5, c, r, Mordant Blue, C, 1, Direct Green 6, c, r, Basic Green 4. C,1, Basic Green 6, C,1, Disperse Yellow 164, C,1, Solvent Yellow 77, etc. can be preferably used.

On the other hand, examples of pigments include yellow lead, cadmium yellow, mineral fast yellow, navel yellow,
Naphthol Yellow S5 Banza Yellow G Rujiren
Yellow TGL, C, 1, Pigment Yellow 17,
Paris First Yellow 3120. Permanent yellow NCG, tartrazine lake, red yellow lead, molybdenum orange, permanent orange GTR.

Pyrazolone Orange, Benzidine Orange G1 Cadmium Red, C,1, Pigment Red 5, Permanent Red 4R, Watching Red Calcium Salt, Eosin Lake, Brilliant Calgin 3B,
Manganese Purple, Fast Violet B1 Methyl Violet Lake, Navy Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Fast Sky Blue, Indanthrene
Blue BC, chrome green, chromium oxide, pigment green B, malachite green lake, final yellow green G, etc. are preferably used.

Next, preferred combinations of colorants when the toner of the present invention is a blackened toner will be described in some detail below.

In the present invention, in order to obtain a blackened toner, blue pigments C,! , Pigment Blue 15, a disazo compound represented by the following formula (1), and a monoazo compound represented by the following formula (2) are preferably combined.

In the above formula (1), X and Y are respectively -H and -C
H, or -0CR, where X is -0CH3i
and Y is preferably -H.

R4 In the above formula (2), R1, R2% Ra, R5 and R6 are -H, -CJZ, respectively.

-CH,, -0CR3, -NO2 or -So, N(C2
H6)2 is shown, but -Cjl, -0CH3, -502N
(C2I!) 2 or -H is preferred.

As the disazo compound (1), known disazo dyes and pigments can be used as they are, but disazo pigments such as C.I. I. Pigment Yellow 12 (Pigment Yellow12),
C,1, Pigment Yellow 13, C0■, Pigment Yellow 14, C,1, Pigment Yellow 17
, etc. are preferably used, especially when X =
C, I which is OCH3.

Pigment Yellow 17 is particularly preferably used because the amount of charge is less dependent on the environment.

On the other hand, as the monoazo compound (2), known dyes and pigments can be used as they are, but monoazo pigments, and even C,1, Pigment Red 2 (Pigment
ment Red 2), C, I, pigment
Red 5. C,1, Pigment Red 17, C,1,
Pigment Red 21, C, I.

Pigment Red 97. C,! , Pigment Knot 114 and the like are preferably used, and C1 and Pigment Red 5 are particularly preferably used from the viewpoint of dispersibility in used resin and charge controllability.

In addition, examples of combinations of other preferred embodiments for obtaining a blackened toner include an insoluble azo red pigment, a disazo yellow pigment, and a copper phthalocyanine blue pigment; or a xanthine red dye, a pyrazolone yellow dye, and copper. There are second class phthalocyanine blue pigments, more specifically, C
,1, Pigment Yellow 17 (Pigment
Yellow 7) and C. I. Pigment Red 5 and C,1, Pigment Blue 15
): C, 1, Solvent Yellow 21 (5ol
vent Yel low 21) and C, 1, Basic Red 5 (Basic Red 5) and C,
1, Pigment Blue 15. C, 1, Pigment Yellow 4
) and C,1, Pigment Red 17 (Pigmen
t Red 17) and C,I.

Pigment Blue 152 is particularly preferably used.

In the present invention, the total amount of the two or more colorants mentioned above is 1.5 to 20.0 parts per 100 parts of the binder resin.
It is preferable that the amount is about 100%.

In particular, in an embodiment of the present invention in which a blackened toner is obtained by a combination of three types of colorants as described above, the above-mentioned disazo compound (1), monoazo compound (2), and C, 1, pigment. Blue 15 (3) is 0.5 to 10 parts (0.5 to 10 parts) per 100 parts of the binder resin.
Furthermore, it is preferable to add 0.7 to 8.5 parts).

In this case, if the above-mentioned amount of compound (1), (2) or (3) is less than 0.5 part, it is difficult to obtain a substantial black color by the combination of these compounds, and it is difficult to obtain a sufficient black color by combining these compounds. Unable to obtain image density. On the other hand, if the blending amount of any of the above components exceeds 10 parts, the toner charge amount becomes highly dependent on the environment, and furthermore, the spent toner on the carrier is accelerated during durability. In addition, (1) above,
The quantitative ratio in the combination of the three compounds (2) and (3) is C,1, Pigment Blue 15 (compound (3)
)) is 0.5 to 1 part of disazo compound (1).
It is preferable that the monoazo compound (2) be 30 parts and 0.5 to 5.0 parts of the monoazo compound (2) from the viewpoint of the balance between spectral properties and charging properties.

In addition, in the present invention, in order to slightly adjust the color, if necessary, known direct dyes and dispersions whose triboelectric charge does not fall within the above-mentioned range of ±10 μGig may be used, within a range that does not impair the purpose of the present invention. It is also possible to use dyes, acid dyes, basic dyes, oil-soluble dyes or pigments as auxiliary colorants. The amount (total amount) of these auxiliary colorants added is 1/2 of the total amount of components constituting the toner other than the binder resin.
Below, it is further preferable that it is 173 or less (particularly 1/1O or less).

As the binder resin used in the toner of the present invention, any known binder resins can be used without particular limitation, but for example,
Polystyrene, polychlorostyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer , styrene-maleic acid copolymer, styrene-acrylic ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-
octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylate ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate) styrenic resins (including styrene or styrene substituted products) such as styrene-α-methyl chloroacrylate copolymers, styrene-acrylonitrile-acrylic acid ester copolymers, etc. (monopolymer or copolymer); vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene resin Ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, etc. can be used alone or in combination of two or more.

Among the above-mentioned resins, styrene-
(Meth)acrylic acid resin, styrene-(meth)acrylic acid ester resin, and polyester resin are preferably used.

Furthermore, in the present invention, a diol component represented by the following formula and a carboxylic acid component (for example, fumaric acid, maleic acid, A polyester resin obtained by cocondensation polymerization with an acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) is particularly preferably used.

(In the formula, R is ethylene or propylene group, x, y
are each an integer of 1 or more, and the average value of X+y is 2 to 10. ) On the other hand, as the carrier used in combination with the toner of the present invention, either a magnetic substance or a non-magnetic substance can be used, for example, iron, steel, ferrite, Ba- Fe ferrite, Cu-Fe
Ferrite, Zn-Fe ferrite, 5r-Fe ferrite, Cu-Zn-Fe ferrite, chromium, cerium, and magnesium oxides, or zircon, silicon, silicon dioxide, and the like are used. These substances have an average particle size of 20 to 100 μm, preferably 25 to 70 μm,
More preferably, it is used as particles of 30 to 65 μm.

These carrier particles may be surface-coated, if necessary.

As these coating materials, resins such as fluororesin, styrene resin, acrylic resin, and epoxy resin can be preferably used alone or in combination.

The toner of the present invention may be mixed with various additives, such as a charge control agent, a lubricant, finely powdered silica, and PVDF (polyvinylidene fluoride) powder, as required.

The toner of the present invention is produced by kneading and dispersing the above-mentioned two or more colorants in a binder resin and pulverizing (and classifying if necessary) according to a conventional method, so that the volume average particle diameter is preferably 5. Obtained as particles of ~15 μm. During the above-mentioned kneading, from the viewpoint of improving the miscibility of the colorants with each other and their dispersibility in the binder resin, the two or more colorants mentioned above are first thoroughly mixed and then dispersed in the binder resin. It's okay.

As described above, according to the present invention, by incorporating a colorant with a triboelectric charge amount of 2 fi 1 or more within a certain range into the binder resin, charging characteristics and environmental stability can be improved. A chromatic to black toner with excellent properties can be obtained.

As the above two or more colorants, especially blue pigments C, 1,
Pigment Blue 15 and a specific disazo compound,
When using a specific monoazo compound, based on the properties of these three compounds in the binder resin, it not only shows good electrophotographic properties such as charging properties, but also has excellent spectral properties, especially in the infrared. A blackened toner is obtained, which provides a good black image and at the same time allows for extremely easy detection of developer concentration.

Such a blackened toner is suitably used as a black toner for color electrophotography in a developing method using a two-component developer, particularly for color electrophotography in which accurate control of developer concentration is extremely important.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example] 50 parts by weight of a black mixture was obtained. This black mixture (
5.0 parts), hydroxypropylated bisphenol A
100 parts by weight of a polyester resin (flow tester softening point: 100 tl) obtained by condensing and fumaric acid was added, and the mixture was sufficiently premixed using a Henschel mixer, and then melt-kneaded using a roll mill to obtain a kneaded product. After cooling the kneaded product, it was coarsely ground using a hammer mill, and then finely ground using an air jet type pulverizer. Further, the obtained finely ground product was classified to select a particle size of 5 to 20 μm, and 0.3 part of finely powdered silica was externally added (mixed) to obtain the blackened toner of the present invention.

The triboelectric charge amounts of the colorants A1%A2 and A3 measured by the blow-off method as described above are T1=ta, 2, T2=17.3, and T3=25.0, respectively.
(μc/g) (Regarding any of T□, T2, and T3 as a reference, other charge amounts are within the range of ±10 μc/g).

100 parts by weight of this toner and Fe-Zn-Cu ferrite coated with fluorine acrylic resin (average particle size 50 μm,
900 parts by weight of carrier particles) were mixed to prepare a developer.

FIG. 2 shows the spectral diffuse reflectance of this developer in the visible and infrared regions, and the spectral diffuse reflectance of the fluorine acrylic resin-coated ferrite particles used as a carrier. Looking at FIG. 2, it can be seen that the difference in reflectance between the carrier particles and the toner of the present invention is large in the infrared region.

An image forming test was conducted by applying the developer obtained above to a color electrophotographic copying machine as shown in a schematic side sectional view in FIG.

Referring to FIG. 3, the electrostatic latent image formed on the photoreceptor drum 10 equipped with a positively chargeable CdS photoreceptor is visualized by the developer in the developing device 16a, and has already been applied to the gripper 20. The developed toner powder image was transferred by the transfer corotron 21 to the transfer material held on the transfer drum 19 by the transfer corotron 21 .

Thereafter, the transferred image was fixed and fixed on the transfer material using a fixing means to obtain a copy.

A durable image forming test was conducted using the above copier, but 1
Clear images with no fogging were obtained even after 10,000 prints. In addition, there was no toner fusion to the drum 10. At this time, the ratio of the initial charge amount of the developer to the charge amount after 10,000 copies (1
The charge amount after 10,000 sheets/initial charge amount) is 1.14,
There was almost no change in the amount of charge.

This developer has low temperature and low humidity (15℃, 10%RH), normal temperature and room temperature (23℃, 60%RH) and high temperature and high temperature (32℃).
Figure 4 shows the changes in the amount of charge under the following conditions: Looking at FIG. 4, it can be understood that the developer containing the toner of the present invention is stable in terms of charge, despite such extreme environmental changes.

The amount of triboelectric charge shown in FIG. 4 is a value measured using the above-mentioned resin-coated ferrite particle carrier and the above-mentioned blow-off method after being left in each environment for 2 days at a toner concentration of 10% in the developer.

Marugame 4962 Instead of the polyester resin of Example 1, styrene-diethylaminoethyl methacrylate resin copolymerization ratio 10:1
．． A blackened toner and developer of the present invention were obtained in the same manner as in Example 1, except that a weight average molecular weight (weight average molecular weight: toooo) was used.

A durable image forming test was conducted in the same manner as in Example 1, except that this developer was used and the apparatus shown in FIG. 3 equipped with an OPC (organic photoconductor, negatively chargeable) photosensitive drum 10 was used. Even after 50,000 sheets, good images were obtained.

The environmental dependence of the change in the amount of charge of the developer is shown in the graph of FIG.

Example 3 A blackened toner and developer of the present invention were obtained in the same manner as in Example 1, except that a black mixture (3.0 parts) obtained by mixing the components of the above formulation was used.

The above colorant A1. The amount of triboelectric charge in the blow-off method for A2 and A3 is T1=12.0 and T2=
19.5, T3=25.0 (μc/g) (T
Based on 2=19.5, T□ and T3 are ±10μ
c/g).

Using this developer, 20,000 copies were repeatedly made under high temperature and high humidity conditions in the same manner as in Example 1, but good images were obtained with no change in image bleeding or fogging from the initial stage.

K Turtle ■1 In addition to the colorants A 1 , A2 and A3 of Example 3,
A blackened toner and developer of the present invention were obtained in the same manner as in Example 3, except that a black mixture (3.1 parts) obtained by mixing 0.1 part of phthalocyanine green as a color tone modifier was used. .

Using this developer, 20,000 copies were repeatedly made under high temperature and high humidity conditions in the same manner as in Example 1, but good images were obtained with no change in image bleeding or fogging from the initial stage.

Comparative Example 1 A toner was prepared and a developer was obtained in substantially the same manner as in Example 1, except that 5 parts by weight of carbon black was used in place of the black mixture (5.0 parts) of Example 1.

The spectral diffuse reflectance of this developer is shown in FIG.

It can be seen that the reflectance is small in the visible and infrared regions as well, making it unsuitable for developer concentration detection based on reflection density.

Comparative Example 2 A black mixture (15, 2
A toner and a developer were obtained in the same manner as in Example 1, except that Example 1) was used.

The above C,1, Pigment Red 48, C,1, Pigment Blue 15, and C,! The triboelectric charge amounts of Pigment Yellow 1 are -10.5 and +25., respectively.
0.+3.8 (μc7g).

Although it was possible to obtain a sufficient reflectance of infrared light through spectral reflectance measurement, when a durability image formation test similar to that in Example 1 was conducted, fogging on the image significantly increased after 8,000 sheets were printed. It became practically impossible.

In this developer, the colorants had poor affinity with each other and also had poor dispersibility into the binder resin. While the initial charge amount of this developer was -11.3 μc/g, the absolute value of the charge amount was quite low at -3.8 μc/g after 8,000 sheets were printed.

From this, it is presumed that the toner of Comparative Example 2 was not given a sufficient amount of charge during durability, resulting in a significant increase in fog.

Further, FIG. 4 shows changes in the amount of charge of this toner under three environments such as room temperature and room temperature. Referring to FIG. 4, although the toner of Comparative Example 2 has an almost appropriate charge amount at room temperature, there is a significant difference in the charge amount under low temperature, low humidity, high temperature and high temperature conditions. The toner was unstable.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view showing an example of a triboelectric charge amount measuring device used in the present invention, Fig. 2 is a graph showing the spectral reflection characteristics of the toner etc. obtained in Example 1, and Fig. 3 is a graph showing the spectral reflection characteristics of the toner etc. obtained in Example 1. FIG. 4, which is a schematic side sectional view showing an outline of the color electrophotographic copying machine used, is a graph showing the amount of charge of the toners of Examples and Comparative Examples under each environment. 1... Conductive screen (400 mesh) 2...
Measuring container 3...Metal lid 4...Suction device 5...Suction port 6...Air volume control valve 7...Vacuum gauge 8...Electrometer 9...Condenser 10... Photosensitive drum 16...Developing section 19...Transfer drum 20...Gripper 21...Transfer corotron 22...Representative diagram of separation claw: Fig. 4

Claims (1)

[Scope of Claims] 1. A toner comprising a binder resin and two or more colorants; An electrophotographic toner, characterized in that the amount of triboelectric charge is within the range of ±10 μc/g. 2. The two or more colorants include blue pigment C. I. The electrophotographic toner according to claim 1, comprising Pigment Blue 15, a disazo compound represented by the following formula (1), and a monoazo compound represented by the following formula (2). ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) (In the above formula (1), X and Y are -H and -, respectively)
Indicates CH_3 or -OCH_3. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(2) (In the above formula (2), R_1, R_2, R_3, R_4,
R_5 and R_6 are -H, -Cl, -C, respectively
H_3, -OCH_3, -NO_2 or -SO_2N(
C_2H_5)_2 is shown. )