JPH0862889A - Photosensitive toner - Google Patents

Abstract

PURPOSE: To obtain a photosensitive toner using carbon black as a colorant and without causing fog at a high temp. and humidity by incorporating carbon black, a photoconductive material as inorg. substances and a coupling agent into particles of org. resin for fixation. CONSTITUTION: A photoconductive material, a sensitizing dye, carbon black as a colorant and a coupling agent are incorporated into single structural particles of a resin for fixation. The resin for fixation is, e.g. styrene resin, acrylic resin, styrene-acrylic resin, polyester resin or butyral resin. Any of silane and titanium coupling agents may be used as the coupling agent. The photoconductive material is, e.g. an inorg. photoconductive material such as zinc oxide, titanium oxide, cadmium sulfide or selenium. Any of known various sensitizing dyes may be used as the sensitizing dye.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive toner having photoconductivity, and more particularly to a black photosensitive toner using carbon black as a colorant.

[0002]

2. Description of the Related Art As an alternative to an image forming method using a photoconductive photosensitive member and a charging toner, an image forming method using a photoconductive photosensitive toner is used for an image of a laser beam printer or the like. It is being adopted in forming devices. In the above image forming method, first, the photosensitive toner in the high resistance state which has not been irradiated with light is charged alone or in a mixture with a carrier.

Then, the charged photosensitive toner is uniformly electrostatically adhered to the surface of the conductive substrate to form a thin layer of the photosensitive toner on the surface of the substrate. Next, the thin layer of the above-mentioned photosensitive toner is exposed to a predetermined pattern corresponding to a formed image by using a semiconductor laser or the like, the photosensitive toner in the portion irradiated with light becomes conductive, and an electric charge is generated on the substrate. The charge potential drops by escaping.

Thereafter, when an electric field having the same polarity as that of the photosensitive toner is applied from the back surface of the transfer target such as paper to the thin layer of the photosensitive toner in contact with the transfer target, the photosensitive toner not irradiated with light is a substrate. The photosensitive toner, which remains on the surface and whose charging potential is lowered by irradiation with light, is transferred to the paper, and a toner image corresponding to the exposure pattern is formed on the paper surface. The photosensitive toner used in the above-mentioned image forming method is usually constituted by containing a photoconductive material, a sensitizing dye and a colorant in particles of a single structure composed of a fixing resin. Such a photosensitive toner is produced, for example, by a so-called spray dry method in which a solution prepared by dissolving or dispersing the above components in a suitable solvent is sprayed and dried.

As the photoconductive material, zinc oxide (Zn oxide) is used.
An inorganic photoconductive material such as O) is used, and a cyanine dye (λ _max = 780 nm) is generally used as a sensitizing dye. The cyanine dye sensitizes zinc oxide (λ _max = 380 nm), which is insensitive to light in the visible or infrared region used as a light source of an image forming apparatus, such as a semiconductor laser light, and is sensitized to a sensitivity region of a photosensitive toner. Is added in order to spread to the vicinity of the wavelength of the light source of the image forming apparatus.

Dyes are mainly used as colorants,
Among them, a quinone dye that does not have a functional group that affects the sensitivity characteristics of the photoconductive material is preferably used. Further, in the case of a black photosensitive toner, in order not to affect its sensitivity characteristics, a dye of a plurality of colors which does not absorb in the sensitivity range of the sensitizing dye, for example, a dye of three colors of cyan, magenta and yellow is used together. It is colored black.

[0007]

However, since the dye has a high hygroscopicity, the photosensitive toner using the dye is apt to escape the charging potential especially when used in a high humidity condition, so that the toner is not formed in the blank portion of the formed image. There is a problem that so-called fogging that adheres occurs, and the fog density of the formed image is significantly increased.

Further, the dye-colored photosensitive toner has a high dark temperature value, that is, the temperature value of the current value without light irradiation is high, and the dark current value greatly increases as the temperature rises. When used, there is a problem that not only the fog density of the formed image is greatly increased as in high humidity, but also the image density is significantly decreased. Further, in the case of a black photosensitive toner, dyes of a plurality of colors are used as described above. However, since the dyes have weak coloring properties, the image density of the solid portion of the formed image may be reduced, the color may be uneven, and the tint may be weakened. Graying of black tends to occur, and it is necessary to add a large amount of dye in order to obtain sufficient blackness. However, in that case, there is a problem that the photosensitivity of the photosensitive toner is lowered.

Therefore, the present inventors have examined the use of carbon black as the colorant for the photosensitive toner, instead of the dye having various problems as described above. Since such carbon black does not have hygroscopicity, the photosensitive toner using it as a colorant has improved moisture resistance, and when used under high humidity conditions, it does not form a formed image like a dye-colored photosensitive toner when used under high humidity conditions. Fog density does not increase significantly.

Further, the photosensitive toner colored with carbon black has a low temperature dependence of the dark current value, and the dark current value does not greatly increase even at high temperature unlike the photosensitive toner dyed with a dye. Therefore, the fog density does not significantly increase or the image density does not significantly decrease when used under high temperature conditions. Furthermore, carbon black has a stronger coloring power than dyes, and a sufficient amount of blackness can be obtained with the addition of a small amount, and since it itself has conductivity, it must have both sufficient blackness and high photosensitivity. You can

Moreover, since carbon black is cheaper than the dye, the manufacturing cost of the photosensitive toner can be reduced. However, the inventors of the present invention have found that, in the conventional structure, when the colorant is simply changed to carbon black, the moisture resistance is still insufficient, especially when used under high temperature and high humidity conditions. It has become clear that is likely to occur.

An object of the present invention is to provide a photosensitive toner which uses carbon black as a colorant and which does not cause fogging under high temperature and high humidity conditions.

[0013]

According to the studies made by the present inventors, carbon black and photoconductive materials, which are inorganic substances, and fixing resins, which are organic substances, are used to form a photosensitive toner by a spray dry method. It was found that since they were not sufficiently integrated at the time of manufacturing, the humidity resistance becomes insufficient under severe conditions of high temperature and high humidity, and fogging occurs.
That is, since the carbon black and the photoconductive material have insufficient wettability with the fixing resin and the like, in the formed photosensitive toner, a very fine gap is generated at the interface with the fixing resin, and this gap is , As a result of water being adsorbed under particularly severe conditions of high temperature and high humidity, the charging potential easily escapes,
Fogging occurs.

Therefore, as a result of various investigations by the present inventors to improve the integrity of carbon black and the fixing resin, addition of a coupling agent to the toner particles causes a decrease in moisture resistance. The inventors have found that the formation of gaps is prevented, the integrity of the photosensitive toner is improved, and the occurrence of fogging under severe conditions of high temperature and high humidity can be prevented, and the present invention has been completed.

That is, the photosensitive toner of the present invention comprises a photoconductive material in particles of a single structure composed of a fixing resin,
It is characterized by containing a sensitizing dye, carbon black as a colorant, and a coupling agent.
The present invention will be described below. As described above, the photosensitive toner of the present invention is a single-structure particle composed of a fixing resin, which contains a photoconductive material, a sensitizing dye, carbon black as a coloring agent, and a coupling agent. It is composed by including it in the inside.

Examples of the fixing resin include styrene resin, acrylic resin, styrene-acrylic resin, polyester resin, butyral resin and the like. Such fixing resins may be used alone or in combination of two or more. As the coupling agent contained in the particles of a single structure composed of the fixing resin, either a silane type or a titanium type can be used, but in particular, the following general formula (1):

[0017]

Embedded image

(In the above formula, R represents an organic functional group having a substituent which binds to an organic material, and is represented by Y ¹ , Y ² and Y.
³ is the same or different and represents a hydrolyzable group that reacts with an inorganic material), and a silane coupling agent represented by the formula (3) is preferably used. Examples of the organic functional group corresponding to the above-mentioned group R include a vinyl group, a methacryl group, a glycidoxy group, an amino group, a mercapto group, a chloropropyl group and the like, and these groups are bonded to the tip of an alkylene chain or the like. Also included are groups and the like.

Examples of the hydrolyzable group corresponding to the groups Y ^{1 to} Y ³ include an alkoxy group having 1 to 6 carbon atoms and a chlorine atom. Specific examples of such a silane coupling agent include, but are not limited to, formula (2):

[0020]

Embedded image

Γ-methacryloxypropyltrimethoxysilane represented by the following formula (molecular weight 248, specific gravity 1.04, boiling point 255 ° C., trade name SZ603 manufactured by Toray Silicone Co., Ltd.
0), formula (3):

[0022]

[Chemical 3]

Γ-glycidoxypropyltrimethoxysilane represented by (molecular weight 236, specific gravity 1.07, boiling point 2
90 ° C, trade name SH6040 manufactured by Toray Silicone Co., Ltd.,
And equation (4):

[0024]

[Chemical 4]

Γ-chloropropyltrimethoxysilane represented by (molecular weight 198, specific gravity 1.08, boiling point 196
C., Toray Silicone Co., Ltd., trade name SH6076) and the like. Such coupling agents may be used alone or in combination of two or more.

The coupling agent is preferably added in a proportion of 0.2 to 10% by weight based on the total amount of the toner constituting material containing the coupling agent. If the addition amount of the coupling agent is less than the above range, the effect of adding the coupling agent is not sufficient, and the moisture resistance of the photosensitive toner becomes insufficient,
Fogging may occur especially under high temperature and high humidity conditions. On the other hand, when the amount of the coupling agent added exceeds the above range, the excess coupling agent affects the sensitivity characteristics of the photosensitive toner, and the sensitivity of the photosensitive toner decreases,
The image density may decrease. The amount of the coupling agent added is preferably 0.4 to 2.0% by weight, especially within the above range, in consideration of both improvement in moisture resistance and photosensitivity of the toner.

Examples of the photoconductive material include inorganic photoconductive materials such as zinc oxide, titanium oxide, cadmium sulfide and selenium. Such photoconductive materials may be used alone or in combination of two or more. The photoconductive material is 100 to 50 parts by weight with respect to 100 parts by weight of the fixing resin.
It is preferably added in a proportion of 0 parts by weight. If the addition amount of the photoconductive material is less than the above range, the photosensitivity of the photosensitive toner may be insufficient. On the contrary, if it exceeds the above range, the heat fixing property of the toner may be deteriorated. . Note that the addition amount of the photoconductive material is, in consideration of the compatibility of the photosensitivity and the heat fixing property of the toner, within the above range, particularly 200
It is preferably 400 parts by weight.

As the sensitizing dye, any of various conventionally known sensitizing dyes can be used. Particularly, as a sensitizing dye having a high sensitizing effect when combined with carbon black, a compound represented by the general formula (5 ):

[0029]

[Chemical 5]

(Wherein X ¹ , X ² , X ³ and X ⁴ are
The same or different, a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group or a hydrogen atom is shown, and M is a monovalent metal atom. ), An erythrosine compound represented by the general formula (6):

[0031]

[Chemical 6]

(Wherein X ⁵ , X ⁶ , X ⁷ and X ⁸ are
The same or different, a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group or a hydrogen atom is shown. ) A phenol sulfonephthalein compound represented by
(7):

[0033]

[Chemical 7]

(Wherein X ⁹ , X ¹⁰ , X ¹¹ and X ¹² are
The same or different, a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group or a hydrogen atom is shown. ) The fluorescein-based compound represented by. Of these, the general formula
Specific examples of the erythrosine-based compound represented by (5) include compounds represented by the formula (8) in which X ^{1 to} X ⁴ in the formula are all iodine and M is sodium:

[0035]

Embedded image

3 ', 6'-dihydroxy-represented by
2 ', 4', 5 ', 7'-Tetraiodospiro [isobenzofuran-1 (3H), 9'-[9H] xanthene]
Examples thereof include disodium salt of -3-one [λ _max = 550 nm, also known as erythrosine, for example, erythrosin B (trade name, manufactured by Ciba-Geigy), erythrosine J (trade name, manufactured by BASF).

Specific examples of the phenolsulfonephthalein compound represented by the general formula (6) include compounds represented by the formula: wherein X ^{5 to} X ⁸ are bromine.
(9):

[0038]

[Chemical 9]

3,3 ', 5,5'-tetrabromophenolsulfonephthalein [λ _max = 620 n
m, also known as bromphenol blue]. Further, as a specific compound of the fluorescein compound represented by the general formula (7), for example, a compound of the formula (10) in which X ^{9 to} X ¹² in the above formula are all hydrogen:

[0040]

[Chemical 10]

Examples include 3 ', 6'-dihydroxyspiro [isobenzofuran-1 (3H), 9'-[9H] xanthen] -3-one [λ _max = 510 nm, also known as fluorescein]. Such sensitizing dyes may be used alone or in combination of two or more.

The amount of the sensitizing dye added is preferably 0.01 to 0.5% by weight based on the amount of the photoconductive material used. If the addition amount of the sensitizing dye is less than the above range, the sensitizing action may be insufficient and the photosensitivity of the photosensitive toner may not be sufficiently obtained. Since the sensitizing dye absorbs light and interferes with the sensitizing action of the sensitizing dye, the photosensitivity of the photosensitive toner may be decreased. Considering the photosensitivity of the photosensitive toner, the addition amount of the sensitizing dye is preferably about 0.1% by weight even within the above range.

Although carbon black having various physical properties can be used as the carbon black, the average particle size is in the range of 15 to 30 nm in consideration of the dispersibility in the fixing resin and the coloring property of the photosensitive toner. And carbon black having a pH of less than 6 is preferably used in the present invention.
Carbon black having an average particle size of less than 15 nm easily aggregates and has insufficient dispersibility in the fixing resin.
It is difficult to uniformly disperse in the photosensitive toner, and carbon black tends to be exposed on the surface of the toner. Therefore, the charging potential is likely to escape, fogging may occur, and the fog density of the formed image may increase.

On the other hand, carbon black having an average particle size of more than 30 nm has a low degree of blackness and a weak coloring power, so that the image density of solid portions of the formed image is reduced, the color is uneven, and the grayness of black is caused by the fading of the tint. May occur. In addition, when a large amount of carbon black is added to prevent this, the dark current value increases and the charging potential decreases accordingly, which may cause a decrease in image density and fog.

The average particle size of carbon black is 16 to 27 n, especially in the above range, in consideration of the coloring property.
It is preferably m. Further, since carbon black having a pH of 6 or more has insufficient dispersibility in the styrene-acrylic fixing resin, the charging potential is likely to escape, fogging occurs, and the formed image is The fog density may increase.

The pH of the carbon black is preferably 2-5, especially within the above range, considering the dispersibility in the fixing resin. Examples of carbon black that satisfies such conditions include grades such as furnace black HCF and MCF. Specifically, for example, product name MOGUL (pH 2.5, average particle size 24 nm) manufactured by CABOT, and product name MA100R (pH 3.5, average particle size 2 manufactured by Mitsubishi Kasei) are used.
2 nm), product name RAUEN125 manufactured by Colombian
5 (pH 2.5, average particle size 23 nm) and the like correspond to this.

The characteristics of the carbon black other than the above-mentioned average particle size and pH are not particularly limited, but the volatile components of the carbon black give an activity to the surface of the carbon black to control the pH thereof, and the dispersibility and the like. Considering that it affects the electrical characteristics, the volatile content is 3-10.
Preferably, it is weight%. Considering that the structure of carbon black influences the conductivity, the dibutyl phthalate oil absorption which is one of the indexes for judging the size of the structure is 50 to 140 ml / 100 m.
It is preferably g. Furthermore, since the surface condition of carbon black also affects the conductivity, the specific surface area is preferably 100 to 400 m ² / g.

The carbon black is based on the fixing resin 1.
It is preferably added in an amount of 6 to 25 parts by weight with respect to 00 parts by weight. If the amount of carbon black added is less than the above range, the blackness of the photosensitive toner may be insufficient. Conversely, if it exceeds the above range, the dark current value increases and the charging potential decreases accordingly. There is a risk that the image density may be reduced or fog may occur.

Considering the coloring property and the fog density of the formed image, the addition amount of carbon black is preferably 7 to 15 parts by weight, especially within the above range. The average particle size of the photosensitive toner of the present invention produced from each of the above components is not particularly limited, but is preferably about 7 to 14 μm, and in an image forming apparatus using the photosensitive toner, a conductive substrate is used. In order to form a uniform toner layer on the upper surface, it is particularly preferably 8 to 13 μm within the above range.

The photosensitive toner of the present invention has the same characteristics as in the prior art.
It is produced by a so-called spray dry method in which a solution prepared by dissolving or dispersing each of the above components in a suitable solvent is sprayed and dried. As a solvent used in such a spray drying method, toluene for dissolving the fixing resin is mainly used, and a lower alcohol or tetrahydrofuran may be used together therewith.

[0051]

EXAMPLES The photosensitive toner of the present invention is described below with reference to Examples,
A description will be given based on a comparative example. Example 1 In a beaker having a volume of 1 liter, 0.072 g of erythrosine represented by the above formula (8) as a sensitizing dye was added in an amount of 10 m.
After dissolving in 1 ml of methanol, add 200 ml to this solution.
Of toluene was added for dilution. Next, 72 g of zinc oxide as an inorganic photoconductive material was added to this diluted solution and ultrasonically dispersed, and then the above formula as a silane coupling agent was used.
1 g of γ-methacryloxypropyltrimethoxysilane represented by (2) (0.95% of the total amount of toner constituent materials) was added and lightly dispersed.

On the other hand, 24 g of styrene-acrylic resin as a fixing resin was dissolved in 600 ml of toluene, and 2.4 g of carbon black (average particle size 24 nm, pH 2.5) as a colorant was dispersed. A solution was prepared, which was added to the beaker and ultrasonically dispersed to prepare a spray-dried liquid. Then, the above spray-dried liquid was spray-dried using an atomizer or a two-fluid nozzle to produce a photosensitive toner having a volume-based central particle diameter D ₅₀ of 12.0 μm. Example 2 As the silane coupling agent, γ represented by the above formula (3)
A photosensitive material having a volume-based central particle diameter D ₅₀ of 11.5 μm in the same manner as in Example 1 except that 1 g of glycidoxypropyltrimethoxysilane (0.95% of the total amount of toner constituent materials) was used. Toner was prepared. Example 3 As the silane coupling agent, γ represented by the above formula (4)
The volume-based central particle diameter D ₅₀ was 11.1 in the same manner as in Example 1 except that 1 g of chloropropyltrimethoxysilane (0.95% of the total amount of the toner constituent materials) was used.
A μm photosensitive toner was prepared. Comparative Example 1 A volume-based central particle size D ₅₀ was 11. in the same manner as in Example 1 except that the silane coupling agent was not added.
A 1 μm photosensitive toner was prepared.

The following tests were carried out on the photosensitive toners of the above Examples and Comparative Examples to evaluate their characteristics. Photosensitivity Test (Preparation of Sample) The photosensitive toners of Examples and Comparative Examples were laid out on the surface of a stainless steel substrate and compression-molded using a press machine. Then, as shown in FIG. A pressed toner layer T was formed.

Next, on the surface of the press toner layer T,
A pair of comb-shaped electrode layers E, E were formed by a vacuum evaporation method so that the teeth of the comb mesh with each other. (Measurement of Current Value) The current flowing through the press toner layer T was obtained by placing the sample in a dark room and applying a voltage of 100 V between the comb-shaped electrode layers E and E without irradiating the press toner layer T with light. The value was measured as a dark current value.

Next, when the above-mentioned pressed toner layer T is irradiated with light having a wavelength of 550 nm (light intensity 40 μW) taken out by using a monochromator for 3.8 seconds, the current value flowing through the pressed toner layer T is converted into light. It was measured as a current value. Then, the photosensitivity (gain) represented by the photocurrent value / dark current value was obtained from the above measured values. The results are shown in Table 1.

[0056]

[Table 1]

From Table 1, it was found that the photosensitive toner of each example to which the silane coupling agent was added exhibited the same photosensitivity as the photosensitive toner of Comparative Example 1 to which the silane coupling agent was not added. Toner reflection density test A sample tube (3 ml) made of polypropylene with one end opened with 0.6 g of each of the photosensitive toners of Examples and Comparative Examples.
Then, a wire mesh filter made of stainless steel (400 mesh) was attached using a double-sided adhesive tape so as to cover the opening of the sample tube. Next, on paper,
A sample was prepared by uniformly sprinkling the photosensitive toner on the paper by tapping the bottom of the sample tube with a finger with the opening of the sample tube facing downward, and then thermally fixing the toner to the paper through a heat roller. Then, the reflection density of this sample was measured with a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.).

The results are shown in Table 2.

[0059]

[Table 2]

From Table 2, it was found that the photosensitive toners of Examples and Comparative Example 1 which were colored with carbon black had sufficient blackness. Environmental resistance test The photosensitive toners of Examples and Comparative Examples were used in the image forming tester shown in FIG. 2 under normal temperature and humidity conditions of 20 ° C. and 65% RH, and high temperature and high temperature of 35 ° C. and 85% RH. A black-and-white image was formed under a wet condition, and the image density (ID) of the black solid part and the fog density (FD) of the blank part were measured by the reflection densitometer. In addition, the charge amount (μC / μC) of each toner under the above-mentioned normal temperature and normal humidity condition and high temperature and high humidity condition.
g) was measured by the blow-off method.

The tester shown in FIG. 2 has a developing device 2, an exposure light source 3, a transfer roller around a conductive base drum 1 along the rotation direction of the base drum 1 (indicated by an arrow in the drawing). 4 and 4 are arranged. The developing device 2 mixes the photosensitive toner in a high resistance state, which has not been irradiated with light, with a carrier to charge it, and adheres it around a sleeve 21 having a magnet inside to form a magnetic brush, which is formed on a substrate. Drum 1
The surface of the base drum 1 is electrostatically adhered to the photosensitive toner t in the magnetic brush by the Coulomb force generated by the application of the bias voltage while being in contact with the surface of the base drum 1. It forms a thin layer of t. Further, the developing device 2 is provided with an exposure light source 3 in a process described later.
Photosensitive toner T whose charging potential has been lowered by exposure from
However, a blade 23 is also provided for collecting in the toner hopper 22 the unexposed photosensitive toner t remaining on the surface of the substrate drum 1 after being transferred onto the paper P by the transfer roller 4.

The exposure light source 3 is for irradiating the thin layer of the photosensitive toner t formed on the surface of the substrate drum 1 with light in accordance with a predetermined pattern corresponding to the formed image, and is formed from a semiconductor laser or the like. Become. The transfer roller 4 is for applying an electric field of the same polarity as the photosensitive toners t and T from the back surface of the transfer roller 4 while bringing the paper P into contact with the thin layer after being exposed by the exposure light source 3. By the application, the photosensitive toner t which is not irradiated with light remains on the surface of the substrate drum 1, but the photosensitive toner T which is irradiated with light and whose charging potential is lowered is transferred to the paper and corresponds to the exposure pattern on the paper. The formed toner image is formed.

The image density results are shown in Table 3, the fog density results are shown in Table 4, and the charge amount results are shown in Table 5.

[0064]

[Table 3]

[0065]

[Table 4]

[0066]

[Table 5]

As can be seen from the above tables, the photosensitive toners of the respective examples show smaller changes in image density, fog density and charge amount under high temperature and high humidity conditions than the photosensitive toners of Comparative Example 1. It was found that it has excellent moisture resistance. Examination of Addition Amount of Silane Coupling Agent The addition amount of γ-chloropropyltrimethoxysilane represented by the above formula (4) as the silane coupling agent to the total amount of the toner constituent materials is set to the value shown in Table 6. A photosensitive toner was prepared in the same manner as in Example 1 except for the above.

Then, each of the photosensitive toners was used in the image forming tester, and black and white under the conditions of normal temperature and normal humidity of 20 ° C. and 65% RH and high temperature and high humidity of 35 ° C. and 85% RH, respectively. An image is formed, and the image density (ID) of the black solid area and the fog density (FD) of the blank area are measured with the above-mentioned reflection densitometer, and the normal temperature and normal humidity conditions as well as high temperature and high temperature are measured. The amount of charge (μC / g) under wet conditions
It was measured by the blow-off method. Further, the photosensitivity (gain) of each photosensitive toner was measured by the above method.

The image density result is shown in Table 6, the fog density result is shown in Table 7, the charge amount result is shown in Table 8, and the gain result is shown in Table 9.

[0070]

[Table 6]

[0071]

[Table 7]

[0072]

[Table 8]

[0073]

[Table 9]

From the above tables, the photosensitive toner containing the silane coupling agent in the range of 0.2 to 10% by weight shows changes in the image density, fog density and charge amount under high temperature and high humidity conditions. It was found that the value of γ was small, the moisture resistance was excellent, and the photosensitivity was high. On the other hand, the photosensitive toner to which the silane coupling agent was not added had large changes in image density, fog density and charge amount under high temperature and high humidity conditions, and its moisture resistance was insufficient. Further, the photosensitivity of the photosensitive toner containing more than 10% by weight of the silane coupling agent tended to lower the photosensitivity.

[0075]

As described above in detail, since the photosensitive toner of the present invention contains carbon black as a colorant and a coupling agent is added, it has various kinds of dyes which conventional toners of dye coloring have. It can solve the above problems and has excellent moisture resistance.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a method of measuring a photocurrent value and a dark current value of a photosensitive toner.

FIG. 2 is an explanatory diagram illustrating a configuration of an image forming tester used for evaluating characteristics of photosensitive toners of Examples and Comparative Examples.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 9/08 365

Claims (2)

[Claims] 1. Particles of a single structure comprising a fixing resin,
A photosensitive toner containing a photoconductive material, a sensitizing dye, carbon black as a colorant, and a coupling agent. 2. The photosensitive toner according to claim 1, wherein the amount of the coupling agent added is 0.2 to 10% by weight based on the total amount of the toner constituent materials.