JPH0614192B2 - Photoconductive toner - Google Patents

Description

The present invention relates to a photoconductive toner used in a color image forming method capable of electrophotographically image-copying a color image electric signal with one exposure, and in particular, a blue conductive toner. The present invention relates to a photoconductive toner which has a photosensitivity to light and exhibits a cyan color.

Conventionally, as a method for storing an electric signal for color image and recording it so that it can be handled, a thermal dyeing method or an ink jet method in which an image is formed by mechanically scanning a coloring means, a toner particle colored in three primary colors is used. There are known an electrophotographic method in which exposure, development and fixing are repeated three times in succession, and a method in which particles containing a colorless sublimable dye are colored on a transfer paper on which a coloring layer is formed. However, for example, in the thermal dyeing method, the ink jet method, and the electrophotographic method, it takes a lot of time to obtain a color image and there is a risk of color misregistration, and the method using the colorless sublimable dye is expensive. Since the transfer paper has to be used, the cost is high.

Therefore, the inventors of the present invention previously disclosed that in Japanese Patent Application No. 58-140150, a color image electrical signal is generated by using a photoconductive toner.
We proposed a so-called one-shot color image forming method that can easily copy an image with one exposure.

That is, this color image forming method uses three types of photoconductive toners: a magenta photoconductive toner that is sensitive to red light, a yellow photoconductive toner that is sensitive to green light, and a cyan photoconductive toner that is sensitive to blue light. These toners are charged in advance, and then the red light is converted into blue light, the green light is converted into red light, and the blue light is converted into green light to selectively erase the charge of the toner. The toner particles that have lost the electrostatic charge are removed by mechanical or electrical means to obtain a color image. Further, according to this method, it is possible to obtain a color image without color misregistration in a short time, and there is also an advantage that the image forming operation is simpler than that of the conventional technique.

By the way, in order to obtain a high-quality color image using the photoconductive toner as described above, these photoconductive toners have excellent spectral sensitivity, that is, they have a sharp photosensitivity in a predetermined wavelength range of visible light. It is necessary to have a large coloring power.

For example, it is necessary to use a photoconductive material in order to impart photoconductivity to the above-mentioned photoconductive toner, but since this kind of photoconductive material has photosensitivity only in a short wavelength region, it is photosensitized. It is common to sensitize a dye so that it has a photosensitivity in an arbitrary wavelength range. However, according to the experiments conducted by the present inventors, it has been found that so-called soot pulling occurs on the short wavelength side of the photosensitivity wavelength range even with such a photosensitizer. Therefore, it is slightly sensitive to light other than the desired wavelength range, and it is extremely difficult to clearly separate this photosensitive sensitivity wavelength range in the visible light range and to have sensitive sensitivity only in each wavelength range. Is.

On the other hand, the above photoconductive toner needs to have a large coloring power in order to obtain a clear image. Therefore, it is necessary to color the photoconductive toner with a coloring material such as various pigments. When the wavelength range extends to a region overlapping with the photosensitivity wavelength range of the photoconductive toner, the photosensitivity is reduced due to the absorption of light by the coloring material itself. Therefore, it becomes impossible to give a very large coloring power.

Therefore, the present invention aims to provide a photoconductive toner suitable for use in the above-described color image forming method, and among them, it has excellent spectral sensitivity, and in particular, is photoconductive which exhibits a cyan color while being sensitively exposed to blue light. The purpose is to provide a toner.

That is, the present invention provides three types of photoconductive toner: a magenta photoconductive toner that is sensitive to red light, a yellow photoconductive toner that is sensitive to green light, and a cyan photoconductive toner that is sensitive to blue light. By using these toners in advance, the blue light obtained by converting the red signal of the color image electric signal, the red light obtained by converting the green signal of the color image electric signal, and the blue signal of the color image electric signal were used. It is exposed to the green light to selectively eliminate the charge of the toner and remove the toner particles that have lost the charge to obtain a color image. 4. A cyan photoconductive toner, which comprises a photoconductor having a photosensitivity in the visible region of a wavelength of 500 nm or less, and a cyan colorant, and in a Munsell color system hue display. It is characterized in that it has a colored hue within the scope of BG～8.0PB.

The photoconductive toner of the present invention is a three-color subtractive primary color, that is, cyan, magenta, and yellow as a positive image of red,
It is used in a color image forming method for forming green and blue color images, and particularly has a cyan hue.

In the above color image forming method, the hue of each toner is important in order to obtain a clear color image, and particularly in the case of cyan color, as a result of repeated studies by the present inventors, the Munsell table It was found that the hue belonging to the range of 5.0 BG to 8.0 PB is the most preferable in the hue display.

This Munsell color system hue display is based on the American painter AHMu.
This is a color arrangement method proposed by nsell. According to this method, it is possible to quantify and express colors quantitatively by comparing with Munsell color chart which is a color sample. Specifically, R (red), Y (yellow), G (green), B (blue), P
The five basic hues of (purple) are selected and arranged so as to divide the hue circle into five equal parts, and the colors YR, GY, BG, PB and RP are arranged in the center of adjacent hues of these basic hues. Finally, the adjacent hues are equally divided into 10 to express 100 hues, and 1R, 2R, 3R, respectively.
, 10R, 1YR, 2YR, ...

According to the Munsell color system hue display described above, the hue actually perceived by human eyes can be expressed, and it is suitable for substantially defining the hue of cyan.

On the other hand, the photoconductive toner of the present invention has a wavelength of 5 which is blue light.
It has a sharp sensitivity to light in the visible light region of 00 nm or less, and further has a sensitivity of 470.
has a maximum sensitivity point in the wavelength range of nm or less, and 480 nm
It is preferable to have 80% or more of the sensitivity in the entire visible light range in the following wavelength range.

As a specific constitution of such a photoconductive toner, by adding a blue photosensitizer having a sensitizing action to blue light having a wavelength range of 500 nm or less, the photoconductive toner can be photosensitized specifically in this wavelength range. 500n in the visible light range as a photoconductor showing conductivity
Examples thereof include those in which a coloring material which has substantially no color absorption in a region of m or less and has a color absorption in a region of 500 nm or more, particularly 600 nm or more and which exhibits the cyan hue described above is added. With the above structure, the coloring material acts as a filter against the photoconductivity in the photoconductive region of 500 nm or more, and the substantial photoconductivity of the photoconductor is in the range of 500 nm or less. Can be limited to That is, since the cyan coloring material generally has a strong coloring absorption particularly in a region of 500 nm or more, particularly 600 nm or more, even if the blue photosensitizer is used, it is still longer than the sensitivity region of 500 nm or less in the long wavelength side. The photosensitivity of the photoconductor, which has unnecessary sensitivity over
The unnecessary absorption on the long wavelength side is reduced and substantially eliminated by being filtered by the coloring absorption of the coloring material. Further, at this time, the coloring material has a sensitivity range of the photoconductor sensitized by the blue photosensitizer, that is, a wavelength of 5 or less.
Since the color absorption is extremely small in the region of 00 nm or less,
It does not reduce the sensitivity of this photoconductor.

By the way, as the material of the photoconductor, sulfur, selenium, or oxides such as zinc, cadmium, mercury, antimony, titanium, bismuth, lead, sulfides, selenides,
Alternatively, anthracene, anthraquinone, polyvinylcarbazole, polyvinylanthracene, polyacetylene, and the like can be given, but zinc oxide is particularly preferably used.

The blue photosensitizer used for sensitizing the photoconductor is 2- [3- (2-carboxyethyl) -2 represented by
(3H) -Benzothiazolidene] methyl-3-carboxylate ethyl benzothiazolium and 1- [3- (2-
Carboxyethyl) -2 (3H) -benzothiazolidene] methyl-3-carboxyethyl benzothiazolium bromide, 2- [3- (2-carboxymethyl) -2
(3H) -benzothiazolidene] methyl-3-carboxylate methylbenzothiazolium, auramine, merocyanine, solar pure yellow, thioflavin T, thioflavin S, acridine yellow and the like. These blue photosensitizers are used by being added in a proportion of 0.01 to 1.0% by weight based on the above photoconductor.

Further, it is also effective to use a sensitization aid together with the above-mentioned blue light sensitizer in order to promote the sensitizing action and so-called supersensitization.
Examples of the sensitization aid include electron affinity compounds such as benzoquinone, chloranil, phthalic anhydride, maleic anhydride, dinitrobenzoic acid and iodine. The addition amount of these sensitization aids is 0.01 with respect to the photoconductor.
It is preferable to use it in a ratio of ˜1.0% by weight.

On the other hand, as the coloring material, inorganic pigments, organic pigments, direct dyes, acid dyes, basic dyes, disperse dyes, oil-soluble dyes, etc. may be used alone or in combination in consideration of hue and the like from pigments and coloring materials. However, for example, inorganic pigments such as Pigment Blue 27 (dark blue), Pigment Blue 28 (Cobalt Blue, Pigment Blue 29 (Ultramarine Blue), Pigment Blue 35 (Cerulean Blue), Pigment Blue 2, Pigment Blue 9, Pigment Blue 15, Pigment Blue). 16, Pigment Blue 18, Pigment Blue 19, Pigment Blue 24, Pigment Blue 60,
Pigment Blue 64, and other organic dyes such as Solvent Blue 2, Solvent Blue 11, Solvent Blue 12, Solvent Blue 25, Solvent Blue 35, Solvent Blue 36, Solvent Blue 55, and Solvent Blue 73. To be The amount of these coloring materials used is 1.
It is preferably in the range of 0 to 100% by weight.

The photoconductive toner of the present invention is the photoconductor or blue photosensitizer,
A coloring material, etc. is an indispensable constituent element, but a resin binder is used for the purpose of binding the above-mentioned elements to each other as necessary, or for the purpose of improving fixation on the copy screen. Agents may be used. As the resin binder, a thermoplastic resin such as an acrylic resin, a styrene resin, a styrene-butadiene copolymer, a polycarbonate resin, a polyvinyl alcohol resin, a polyvinyl acetate resin or a thermosetting resin such as a urethane resin, an epoxy resin or a melamine resin may be used. Resins and the like, which may be used alone or in admixture of two or more. The amount used is preferably in the range of 2 to 50% by weight with respect to the photoconductor.

Further, the photoconductive toner of the present invention is formed by making each of the above materials into particles having a uniform dispersion structure or a concentric sphere structure. Examples of the forming method include a spray drying method and a microcapsule method. .

As described above, the photoconductive toner according to the present invention has a sharp sensitivity in a visible light region having a wavelength of 500 nm or less, that is, it has a selective sensitivity only to blue light and has a substantially cyan color. It is possible to obtain a color image free from color misregistration in a short time by a single-operation electrophotographic method from a color image electric signal by using this photoconductive toner as a cyan color toner because the particles are colored into Become.

Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples.

Example 1 Zinc oxide particles (manufactured by Sakai Chemical Industry Co., Ltd., trade name Sazex 20)
00) 40 parts by weight, formula The blue photosensitizer represented by 2- [3- (2-carboxyethyl) -2 (3H) -benzothiazolidene] methyl-3
-0.03 parts by weight of carboxyethylbenzothiazolium bromide (NK1870 manufactured by Japan Photosensitive Dye Research Institute), 0.03 parts by weight of phthalic anhydride and 80 parts by weight of ethyl alcohol were uniformly ultrasonically dispersed to obtain a dispersion solution.

Next, ethyl alcohol, which is a dispersion medium of this dispersion solution, was dried, and the blue photosensitizer and phthalic anhydride were adsorbed on the surfaces of the zinc oxide particles.

2 parts by weight of an acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., BR102) as a resin binder and a formula as a coloring material are added to the dried material thus obtained. 3 parts by weight of the coloring dye Solvent Blue 11 (color index No. 61525, manufactured by Tokyo Kasei Kogyo Co., Ltd., trade name Sudan Blue) and 180 parts by weight of a dispersion medium toluene are added and mixed in a ball mill for 5 hours to obtain a uniform dispersion. A solution was prepared.

Subsequently, this dispersion solution was spray-dried (mobile minor spray dryer manufactured by Niro Atomizer).
Was spray-dried to obtain a particulate photoconductive toner.

The obtained photoconductive toner had substantially the coloring of the above-mentioned coloring dye, and its hue was examined with reference to the Munsell color chart, and it was judged to be Munsell color system hue display 5.0B.

Further, when the photoconductive toner was sprayed on a conductive substrate and charged by corona charging, the charge retention of the photoconductive toner in a dark place was extremely excellent. The photoconductive toner was irradiated with red light or green light, but the attenuation of the charge of this photoconductive toner was almost the same as the attenuation in the dark, and it showed no sensitivity to red light and green light. Was confirmed.

On the other hand, when the charged photoconductive toner was irradiated with blue light, it was confirmed that the charging was significantly attenuated and the sensitivity was remarkable.

Further, the obtained photoconductive toner was filled between the conductive transparent electrodes and the photocurrent for light irradiation in the visible light region was measured to examine the photoconductive characteristics, and the results shown in FIG. 1 were obtained. . On the other hand, FIG. 2 shows the photoconductive properties of zinc oxide sensitized simply with a blue photosensitizer before adding Solvent Blue 11, which is a coloring material. As can be seen from FIGS. 1 and 2, the photoconductive toner of this example has 40
It has photosensitivity only in the wavelength range of 0 to 480 nm,
Further, the above-mentioned photosensitivity is not reduced by the coloring dye.

Example 2 Zinc oxide particles (manufactured by Sakai Chemical Industry Co., Ltd., trade name Sazex 20)
00) 40 parts by weight, formula The blue photosensitizer 2- [3- (2-carboxymethyl) -2 (3H) -benzothiazolidene] methyl-3 represented by
-Carboxylate methyl benzothiazolium (manufactured by Japan Photosensitive Dye Research Institute, NK1880) 0.04 parts by weight, phthalic anhydride and 80 parts by weight of methyl alcohol were uniformly ultrasonically dispersed to obtain a dispersion solution.

Next, methyl alcohol, which is a dispersion medium of this dispersion solution, was dried, and the blue photosensitizer and phthalic anhydride were adsorbed on the surfaces of the zinc oxide particles.

8 parts by weight of an acrylic resin (BR102 manufactured by Mitsubishi Rayon Co., Ltd.) as a resin binder and a formula as a coloring material were added to the dried material thus obtained. Pigment Blue 60 (Color Index No. 69800, manufactured by Imperial Chemical Industries, Mono Light Blue 3R) shown in Table 1 is added, and 180 parts by weight of acetone as a dispersion medium is added, and the mixture is mixed in a ball mill for 5 hours to obtain a uniform mixture. A dispersion solution was prepared.

Subsequently, this dispersion was sprayed with a mini spray (Yamato Scientific Co., Ltd.,
DL-21) was spray-dried to obtain a particulate photoconductive toner.

The obtained photoconductive toner had substantially the coloring of the above-mentioned coloring pigment, and when its hue was examined with reference to the Munsell color chart, it was determined to be Munsell color system hue display of 3,0PB.

Further, when the photoconductive toner was filled between the conductive transparent electrodes and the photocurrent for light irradiation was measured, it was 400 to 480 in the visible light range (wavelength range of 400 to 700 nm).
The photocurrent was measured only in the wavelength range of nm.

Example 3 Zinc oxide particles (manufactured by Sakai Chemical Industry Co., Ltd., trade name Sazex 20)
00) 300 parts by weight was uniformly dispersed in 500 parts by weight of ethyl alcohol by ultrasonic dispersion.

Next, 0.4950 parts by weight of phthalic anhydride was added to this dispersion solution, and this phthalic anhydride was adsorbed on the surface of the zinc oxide particles. Then, this dispersion solution was suction filtered to remove unadsorbed phthalic anhydride and dried. At this time, when the obtained filtrate was quantified using a spectrophotometer, about 9.9% by weight of the added phthalic anhydride was not adsorbed.

Zinc oxide particles 30 thus adsorbing phthalic anhydride
0 part by weight was uniformly dispersed again in 500 parts by weight of ethyl alcohol by ultrasonic dispersion, 0.2866 parts by weight of the same blue photosensitizer as in Example 1 was added, and the blue photosensitizer was oxidized by the above oxidation. It was co-adsorbed on the surface of zinc particles. Further, this dispersion was suction-filtered to remove the unadsorbed blue photosensitizer, and the liquid was dried. When this filtrate was quantified using a spectrophotometer,
Of the added blue photosensitizer, 5.4% by weight was not adsorbed.

The resin binder polystyrene (polymerization degree: 1600 to 180) was added to 250 parts by weight of zinc oxide particles having the phthalic anhydride and the blue photosensitizer obtained as described above adsorbed on the surface thereof.
0, manufactured by Wako Pure Chemical Industries, Ltd.) 12.5 parts by weight and the same coloring dye as in Example 1 as the coloring material (solvent blue 11) 1
8.75 parts by weight and 1125 parts by weight of a dispersion medium toluene were added and mixed in a ball mill for 5 hours to prepare a uniform dispersion solution.

Next, this dispersion solution was spray-dried in a heated nitrogen gas stream using a spray dryer (Mobile Minor Spray Dryer manufactured by Niro Atomizer) to obtain a particulate photoconductive toner.

The obtained photoconductive toner had substantially the coloring of the above-mentioned coloring dye, and its hue was examined with reference to the Munsell color chart, and it was judged to be Munsell color system hue display 5.0B.

Further, when the photoconductive toner is sprayed on a conductive substrate and charged by corona charging, the charge retention of the photoconductive toner in a dark place is extremely excellent,
Further, the charged photoconductive toner was irradiated with red light or green light. The attenuation of the charge of the photoconductive toner was almost the same as the attenuation in the dark place. It was confirmed that no sensitivity was exhibited.

On the other hand, when the charged photoconductive toner was irradiated with blue light, it was confirmed that the photoconductive toner showed remarkable attenuation of charge and had a remarkable sensitivity.

[Brief description of drawings]

FIG. 1 is a graph showing photoconductive characteristics in an example of a photoconductive toner to which the present invention is applied, and FIG. 2 is a blue photosensitizer 2-
[3- (2-Carboxyethyl) -2 (3H) -benzothiazolidene] methyl-3-carboxyethyl benzothiazolium bromide sensitized photoconductor (ZnO) showing photoconductivity characteristics. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junetsu Seto 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-54-19748 (JP, A) JP Sho 55-83053 (JP, A) Japanese Patent Publication 4-56309 (JP, B2)

Claims (1)

[Claims] 1. A magenta photoconductive toner sensitive to red light, and a yellow photoconductive toner sensitive to green light.
Three types of photoconductive toner, cyan photoconductive toner that is sensitive to blue light, are used, these toners are charged in advance, and blue light obtained by converting the red signal of the color image electric signal and the color image electric signal The green light converted from the green signal and the green light converted from the blue signal of the color image electric signal are irradiated to selectively eliminate the charged electric charge of the toner, thereby removing the toner particles that have lost the charged electric charge. A cyan photoconductive toner that is sensitized to green light for use in a color image format of a system for removing a color image, the photoconductor having a photosensitivity in the visible region of wavelength 500 nm or less, and a cyan color. And a coloring agent having a hue within the range of 5.0 BG to 8.0 PB in Munsell color system hue display.