JP2589389B2 - Black photoconductive toner with photosensitivity in semiconductor laser wavelength range - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a black semiconductive toner having good chargeability and photoconductivity and excellent photosensitivity in a laser wavelength range.

(Prior Art) In recent years, attention has been paid to the use of photoconductive toner as a method of forming a copied image without using a photosensitive drum or the like. This photoconductive toner is obtained by dispersing or dissolving a photoconductive material and a sensitizer in a binder resin.
The toner is granulated by a pulverizing method or a spraying method, and the toner itself has photoconductivity.

An example of an image forming (image forming) method using the photoconductive toner is as follows. That is, the charged photoconductive toner is uniformly adhered and held on a conductive substrate to form a toner layer, image exposure is performed, a copy sheet is overlapped on the toner layer, and corona discharge is performed from the back side of the copy sheet. , The toner image is transferred, and the transferred toner image is fixed on copy paper.

However, even in the above-described process, there is a problem that a difference in charge amount between an exposed portion and a non-exposed portion in a latent image formed after exposure is small due to the generally low photosensitivity of the photoconductive toner. . Attempts have been made to improve the surface potential of the toner layer by performing corona discharge on the toner layer after the formation of the toner layer in order to increase the difference in charge amount, but this has not always been possible. It is also conceivable to increase the ratio of the photoconductive material in the toner to increase the photoconductivity. However, in this case, the toner is less likely to be charged, and the photosensitivity is rather lowered and satisfactory results are obtained. Development of a photoconductive toner which is not obtained, has good chargeability and photoconductivity, and has excellent photosensitivity is desired.

On the other hand, an image forming system using a photoconductive toner is not limited to an analog type image forming apparatus, and in recent years, its use in a laser printer has been studied because the apparatus can be extremely miniaturized. In the past, gas lasers were used as the laser light source for exposing the laser printer.However, it has many advantages such as excellent laser light intensity and stability, direct modulation, and low cost. Semiconductor lasers are increasingly used. The wavelength of this semiconductor laser light is 78
Because it is in the near-infrared to infrared region of 0 nm to 850 nm, research on photoconductive materials showing good sensitivity to wavelengths in this range and dyes as sensitizers for shifting the photosensitive region to infrared light Research is ongoing.

Then, by using zinc oxide as a photoconductive material and using a cyanine dye as a sensitizer, the photosensitive area can be shifted to infrared light. Because it is blue-green and not black, the addition of a black pigment as a colorant is further considered. When carbon black, which is generally used as a black pigment, is used, this carbon black absorbs light in the wavelength range of 780 nm to 850 nm, which is the wavelength range of laser light, so that the photosensitivity of the toner decreases. 780nm ~ 850
As a colorant having a small light absorption at nm, there is a perylene black pigment manufactured by BASF. This pigment does not absorb at around 780 nm unlike carbon black, and can be blackened without greatly reducing the photosensitivity of the toner at around 780 nm.

However, the perylene black pigment has a dark green color, and is not yet satisfactory in blackening the toner. Further, in order to obtain a higher image density, it is necessary to contain 10% by weight or more in the resin alone, especially 30% by weight or more when white zinc oxide is used as the photoconductive material. However, as the content of the perylene black pigment is increased, the chargeability of the obtained toner is reduced, and the photosensitivity is significantly reduced, so that the image density is rather reduced.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a black color while minimizing a decrease in toner chargeability and a decrease in photosensitivity. It is an object of the present invention to provide a black photoconductive toner having a taste and excellent photosensitivity to a wavelength around 780 nm.

(Means for Solving the Problems) The black photoconductive toner having photosensitivity in the semiconductor laser wavelength range according to the present invention comprises a binder resin, zinc oxide, and yellow, magenta, and cyan having no functional groups. Each quinone dye is contained, whereby the above object is achieved. The photoconductive material is preferably an inorganic material.

(Preferred Aspect) The black semiconductive toner having photosensitivity in the semiconductor laser wavelength range according to the present invention comprises a binder resin, a photoconductive material,
And a mixed dye of three colors, which are dispersed or compatible with a solvent or the like, and granulated by a pulverizing method or a spraying method.

As the binder resin, conventionally known resins are used, for example, a styrene-based polymer, a styrene-butadiene copolymer, a styrene-acrylonitrile copolymer, a styrene-maleic acid copolymer, an acrylic polymer, and styrene. -Acrylic copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, acrylic-modified urethane resin epoxy resin, polycarbonate, polyarylate, polysulfone And various polymers such as diallyl phthalate resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin and phenol resin.

As the photoconductive material, zinc oxide, titanium oxide,
Inorganic photoconductive materials such as cadmium sulfide and cadmium oxide are preferably used, and zinc oxide is particularly preferably used because of its high photosensitivity and large memory properties. The added amount of the photoconductive material is preferably photoconductive material / binder resin = 1/1 to 5/1 (weight ratio), and particularly preferably 2/1 to 3/1 (weight ratio).

Then, the toner of the present invention is added with a sensitizing dye together with the above-mentioned photoconductive material to give sensitivity in the near infrared to infrared region. As such a sensitizing dye, a cyanine dye is preferably used. Examples of the cyanine dye include the following.

 A cyanine dye represented by the following formula (A):

(Where R is CH ₃ , C ₂ H ₅ , CH ₂ COOH, C ₂ H ₄ COOH, or CH ₂ CHCHCH ₂ , X is I, Br, Cl, ClO ₄ , or Indicates that A cyanine dye represented by the following formula (B).

Wherein n is an integer in the range of 1 to 7, M and M ′ are independently selected from the group consisting of a hydrogen atom and an alkali metal, and X is an anion of an acid. Is a mixture of a yellow quinone dye, a magenta quinone dye, and a cyan quinone dye. Each dye has a functional group such as a hydroxyl group, a carboxyl group, an amino group, or a sulfoxyl group in the molecule. Having no (functional group).

Examples of the yellow quinone dye include Indanthrene Yellow BY, and examples of the cyan quinone dye include Alizarine Brillian Pure Blue.
Pure Bure) and magenta quinone dyes such as Indanthrene Red 5GK (Indanth
rene Red 5gk).

Since each dye does not have a functional group, when mixed with a photoconductive material such as zinc oxide, each dye does not adsorb to the photoconductive material and adsorbs a sensitizing dye such as a cyanine dye. Does not hinder the photo-conductivity of the obtained toner. For example, dyes having a functional group such as quinone dyes such as Suprance-Violet 4BF and Anthracene Blue SWGG have strong interaction with the photoconductive material and are adsorbed on the photoconductive material, resulting in an increase in cyanine dye and the like. This impairs the adsorption of the dye and lowers the photosensitivity of the toner.

A black dye is obtained by mixing these dyes. Further, the color tone of the black toner can be adjusted by adjusting the amounts of the three colors. The mixing amount of these three color mixed dyes is 1 to 30% by weight based on the binder resin,
It is particularly preferably 5 to 15% by weight, and the blending amount of each dye among the mixed dyes can be arbitrarily determined according to the color tone of the intended toner.

Further, the black photoconductive toner of the present invention may contain a small amount of a perylene black pigment and / or a magenta pigment having almost no light absorption in a wavelength range of 780 nm to 850 nm which is a wavelength range of a laser beam. Such perylene-based black pigments include, for example, perylene-3,4,9,10-tetracarboxylic diimide and the like, and magenta pigments include, for example, Paliogen Red 3910HD (manufactured by BASF) and Paliogen Red 3870HD ( BASF), Chromo Fine Magenta MT201 (Dainichi Seika), Hostapern Pink E-0
2 (Hoechst), Brilliant Carmine FB Pure
(Manufactured by Yamazaki), permanent pink (manufactured by Sanyo), perylene red (manufactured by Okunisha) and the like. These color pigments may be used alone or in combination of two or more.

The amount of the perylene black pigment added is 1 to the binder resin.
~ 5% by weight is preferred. The magenta pigment is preferably added in an amount of 10% by weight to 40% by weight based on the perylene black pigment.

These cyanine dyes may be used alone or in combination of two or more. The addition amount of the sensitizing dye is preferably 0.05 to 0.3% by weight, more preferably 0.1 to 0.2% by weight, based on the photoconductive material such as zinc oxide.

Further, in addition to the above-mentioned components, an auxiliary agent such as a known wax and an auxiliary agent such as a pressure fixing agent may be added to the toner of the present invention, if necessary, according to a known formulation. In the present invention, the term “high photosensitivity” means that the initial surface potential of the charged toner layer is measured, and the surface potential of the toner layer reduced by exposure (irradiation of light) is measured to efficiently charge the toner layer. Means lost.

(Effect of the Invention) Since the black photoconductive toner of the present invention contains each quinone dye of yellow, magenta, and cyan having no functional group, it does not absorb the wavelength in the laser wavelength range. In addition, the present invention provides a black toner that can be blackened without greatly affecting the photoconductive material, has good chargeability and photoconductivity, and has excellent photosensitivity to wavelengths in a laser wavelength range. be able to. There is also an advantage that the color of the toner can be freely adjusted by adjusting the amounts of the three color dyes.

(Examples) Hereinafter, the present invention will be described specifically with reference to examples.

Example 1 Zinc oxide, Grade # 2 (manufactured by Hakusui Chemical) 100 parts by weight Styrene-acrylic resin, PA-525 (manufactured by Mitsui Toatsu Chemicals) 33 parts by weight Quinone dye (three colors not containing functional groups) TON106 (manufactured by Mitsui Toatsu Chemicals) 4 parts by weight Cyanine dye, NK1414 (Japan Photographic Research Institute) ... 0.1 parts by weight Toluene 1000 parts by weight After the above mixture is dispersed and mixed, the average particle size is determined by spray drying. A black semiconductive toner of 10 to 11 μ was obtained.

Example 2 Example 1 was repeated except that the quinone dye was 1 part by weight.
In the same manner as in the above, a black photoconductive toner was obtained.

Example 3 Example 1 was repeated except that the quinone dye was used in an amount of 3 parts by weight.
In the same manner as in the above, a black photoconductive toner was obtained.

Example 4 Example 1 was repeated except that the quinone dye was used in an amount of 5 parts by weight.
In the same manner as in the above, a black photoconductive toner was obtained.

Comparative Example 1 A black photoconductive toner was obtained in the same manner as in Example 1, except that only 2 parts by weight of perylene black pigment (Pailogen Black L0084) was used.

Comparative Example 2 A black photoconductive toner was obtained in the same manner as in Example 1 using a three-color mixed dye TON102 (manufactured by Mitsui Toatsu Chemicals) containing a functional group.

Next, the black photoconductive toners obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were mixed with a ferrite carrier and triboelectrically charged, and charged into a magnetic brush developing device for an electrophotographic copying machine. Then, a photoconductive toner was uniformly adhered on an aluminum substrate to form a toner layer. Next, the monochromatic light (780 n
m) was irradiated for 0.5 seconds, the surface potential before irradiation and the surface potential 1.0 seconds after irradiation were measured, and the decay rate of the surface potential (maximum surface potential decay rate) was measured by a computer connected to a digital oscilloscope. The charge amount of each photoconductive toner was measured by a blow-off method. Table 1 shows the results.

From the results in Table 1, it can be seen that by containing each of the quinone dyes of yellow, magenta, and cyan having no functional group, the color of the toner is black compared to a black semiconductive toner using only a perylene black pigment. , And it was confirmed that blackening was possible without greatly affecting the photoconductive material.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazushige Inoue 1-2-2, Tamazo, Chuo-ku, Osaka City, Osaka Prefecture Inside Mita Kogyo Co., Ltd. (56) References JP-A-1-266554 (JP, A) JP-A-48-63727 (JP, A) JP-A-61-167954 (JP, A) JP-A-64-74555 (JP, A) JP-A-1-202760 (JP, A) JP-A-63-96666 (JP, A) JP, A) JP-A-1-227162 (JP, A)

Claims (1)

(57) [Claims] 1. A semiconductor laser comprising a binder resin, zinc oxide as a photoconductive material, and each of a quinone dye of yellow, magenta, and cyan having no functional group. Black photoconductive toner.