JPS61153660A - Photoconductive toner - Google Patents

Abstract

PURPOSE:To obtain a photoconductive toner high in photosensitivity and superior in fixability by dispersing cores composed essentially of a material generating an electrostatic charge on absorption of light into a matrix composed essentially of charge transfer material in the form of plural domains. CONSTITUTION:The matrix 1 is composed essentially of a material mainly contg. the charge transfer material, and this matrix 1 has both functions of transfer of charge generated by the matrix on light absorption and fixing of the toner. The plural cores 2 made of charge generating material on light absorption are dispersed in the form of domains into the matrix, thus permitting the photoconductive toner to be prevented from deterioration of light utilization efficiency in spite of small sizes of individual cores, and light to be transmitted down to the lower part of the toner by control of the number of the cores, accordingly, charge to be generated from the upper layer to the lower layer by absorption of the light, and hence, photosensitivity to be fully enhanced.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to photoconductive toners used in electrophotography.

[Technical background of the invention and its problems]

Photoconductive toner has the chargeability that conventional toners have,
Development characteristics such as fluidity and electrical resistance, and fixing properties.

It is a multifunctional material that has a new function of photoconductivity in addition to coloring properties. The composition of such a photoconductive toner includes a composition in which a photoconductive substance is uniformly dispersed in an insulating resin, and a composition in which a photoconductive substance is uniformly dispersed in an insulating resin core, and a binder material dissolved in an organic solvent or the like is used on the surface of an insulating resin core. Structures that cover the trade in soldering products are already known.

However, toners with such a structure have problems such as it is difficult to achieve both photoconductivity and fixing properties required of toners, or they cannot be used unless they are made into a single-layer toner layer. .

Furthermore, Japanese Patent Application Laid-Open No. 53-79542 discloses (1) a structure in which a core body mainly composed of a charge transporting substance is coated with a material mainly composed of a charge generating substance by light absorption; A configuration has been disclosed in which a core body mainly composed of a generating substance is coated with a material mainly composed of a charge transporting substance. However, with the toner having the structure (1) disclosed herein, when image exposure is performed on multiple layers, a large amount of light is absorbed in the upper layer of the toner layer, and sufficient light does not reach the lower layer.
As a result, there is a problem that the photosensitivity decreases.

In order to avoid such problems, it is possible to form a single layer of toner, but in reality it is very difficult to form a single layer of fine particle toner, and in reality it takes several to ten layers. This results in a thin layer consisting of several layers of toner, which does not solve the problem. Furthermore, if the layer is too thin, even if a visible image can be obtained by imagewise exposure, the image density will decrease and it will be difficult to obtain a good visible image.

On the other hand, in the case of toner having a structure like (2), if the core body that absorbs light is large, the light irradiated for image exposure will be absorbed in the upper layer of the toner layer, and the lower layer will be absorbed. In addition, if the core is small enough, the light will reach the lower layer of the toner 1, but the efficiency of using the irradiated light will decrease because the core, which is mainly made of charge-generating material, is small. There were still problems such as no improvement in photosensitivity.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and when using a single toner layer formed into a thin layer of several to ten or more layers,
An object of the present invention is to provide a photoconductive toner having high photosensitivity and excellent fixing properties.

[Summary of the invention]

The photoconductive toner of the present invention is characterized in that a plurality of core bodies mainly composed of a substance that generates electric charge by absorption of light are dispersed in a matrix in a matrix mainly composed of a charge transporting substance. .

A schematic cross-sectional view of the photoconductive toner of the present invention is illustrated in FIG. 1. As shown in FIG. It has the functions of both transporting the electric charge generated from the toner and fixing the toner. A plurality of core bodies 2 made of a substance that generates electric charges by light absorption are dispersed in the matrix in the form of domains. By dispersing a plurality of cores 2 in a domain shape within the matrix, the photoconductive toner according to the present invention can be used without reducing light utilization efficiency even if the individual cores are small. By controlling the amount of light, the light can reach the bottom of the toner layer, and as a result, light is absorbed from the top to the bottom of the toner layer, creating a charge.

As a result, it is possible to obtain a sufficient improvement in photosensitivity compared to the conventional method.

In this case, in order to efficiently absorb light in the core, it is necessary that at least the light absorption wavelength range of the matrix layer made of a charge-transporting substance is at least as large as the light absorption of the charge-generating substance due to the light absorption in the core. It is necessary that the main wavelength range and the wavelength range of 200 to 9QQnm do not overlap. If the absorption wavelength ranges of both 1 and 1 overlap in this wavelength range, the amount of light received by the charge-generating substance in the core decreases due to absorption of light by matrix 1, and as a result, the charge generated in the core decreases. and the photosensitivity of the photoconductive toner will decrease. Therefore, the absorption wavelength range of charge-transporting substances and charge-generating substances is 200 to 900.
It is necessary to create a combination that does not overlap within the nanometer range.

In addition, in terms of light absorption in a single layer of the photoconductive toner, it is preferable that the volume average particle size of each core is 173 or less of the volume average particle size of the photoconductive toner, and that It is desirable that the total proportion thereof is 10 volume percent or less. This is because when the volume average particle size of each core exceeds 173 in the toner, the matrix layer, which also has a fixing function, decreases due to the toner containing more than one such core. This is because the fixing function of the photoconductive toner is impaired. In addition, even if the volume average particle diameter of the core is 173 or less of the toner, if the total proportion of the core in the toner exceeds 10 volume percent,
Since the light absorption rate of the core of each toner increases, light is absorbed only in the upper layer of the photoconductive toner layer, and no improvement in photosensitivity can be expected.

Therefore, it is desirable that the proportion of the core in the photoconductive toner is 10% by volume or less. Furthermore, as the particle size of the core becomes smaller, the surface area per unit volume of the core increases, so even if cores of the same weight are contained in the toner, if the particle size of the core is small, each individual The light absorption rate of the toner increases and the photosensitivity of the photoconductive toner layer decreases. Therefore, when the S particle size is small, it is desirable to reduce the proportion of the core in the toner. The volume average particle diameter of the core is 1 of the volume average particle diameter of the photoconductive toner.
It is more preferable that it is /30 or more.

There are no particular limitations on the charge-generating substance by light absorption that can be used in the present invention, but examples include phthalocyanine pigments such as metal-free phthalocyanine, metal phthalocyanine or their halogen derivatives, perylene pigments such as perylene acid anhydride, and bisimidole perylene. , anthraquinone pigments, azo pigments such as monoazo and bisazo, indigo and thioindigo indigoid pigments, quinacridone pigments, cyanine dyes such as merocyanine and cyanine, anthraquinone pigments, anthraquinone pigments, anthraquinone pigments, dibenzpyrenequinone, vilanthrone, and violanthrone fistiso. Polycyclic aromatic pigments such as violanthrone-exposed flavanthrene.

Benzimidazole pigments and the like can be used.

Charge transporting substances that can be used in the present invention include:
Transparent organic photoconductors can be widely used.

For example, a low molecular weight organic photoconductor dispersed in an insulating resin or a photoconductive polymer can be used.

Examples of the former are arylalkane and pyrazoline.

Oxadiazole, hydrazone, styrene, triphenylamine, phenylenediamine, biphenylamine, Calhaf''-/lz, 7/L/olenon-based substances are mixed with polystyrene resin, acrylic resin, methacrylic resin,
Polyester resin, polyethylene, polypropylene.

Polyvinylidene fluoride, polyvinylidene chloride, polyvinyl chloride, ethylene-vinylidene acetate copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-butadiene copolymer, styrene-vinylidene chloride copolymer Examples include those dispersed in polymers, styrene-vinylidene chloride copolymers, styrene-vinylidene fluoride copolymers, styrene-acrylonitrile copolymers, polyethylene waxes, epoxy resins, phenol resins, urethane resins, and the like. The latter polymers include vinylcarbazole, vinylphenylandrane,
Vinylpyrazone, vinylbenzothiophene, vinylpyrene, and heavy adducts or copolymers of these derivatives can be used.

〔Effect of the invention〕

The photoconductive toner of the present invention is a photoconductive toner that has sufficient photosensitivity and sufficient fixing properties when used in a single layer or in several to several thin layers. can be,
It is possible to obtain images that are clearer and have better fixability than conventional methods. Furthermore, the photoconductive toner of the present invention differs from conventional photoconductive toners having a polygonal structure, and due to the structure of the toner, it is not necessary to use special equipment such as a fluidized bed dryer or a spray dryer. It is possible to manufacture it using a device.

[Embodiments of the invention]

Example 1 50 parts by weight of β-type steel phthalocyanine 40 parts by weight of epoxy resin ERL4221 (manufactured by Union Carbide Co.) 10 parts by weight of maleic anhydride were mixed in a kneader.
After dispersing the powder, it was cured by heating at 120'C for 3 hours. The obtained cured product is crushed and classified to have a volume average particle size of approximately 2 μm.
Fine particles for the core were obtained.

Next, we synthesized a charge-transporting substance. first.

Vinyl carbazole 50 parts by weight n-
Butyl methacrylate 35 parts by weight to 70
A monomer solution was prepared by heating to ℃ and mixing. In addition, 1 part by weight of surfactant Emar O (manufactured by Kao Soap Co., Ltd.) Water 200 parts by weight Methanol 35 parts by weight Silicone antifoaming agent TSA730 0.01 part by weight (Toshiba Silicone Co., Ltd.)
Co., Ltd.) as a dispersion medium and heated to 65° C., the monomer solution was added and stirred to form an emulsified state. Thereafter, 10 parts by weight of potassium persulfate (4% by weight aqueous solution) 10 parts by weight of sodium acid sulfite (4% by weight aqueous solution)
Parts by weight were dropped into the above-mentioned emulsified solution over 30 minutes, and the monomers were reacted to synthesize a vinylcarbazole 110-butyl methacrylate copolymer. The molar ratio of vinylcarbazole in the obtained copolymer was 40 mol percent, and the glass transition temperature was about 75°C.

The core obtained in this way: 5 parts by weight of vinyl carbazole/n-butyl methacrylate, 95 parts by weight of a copolymer of vinylcarbazole and n-butyl methacrylate were heat kneaded in a pressure kneader, then pulverized and classified by φ to obtain a light particle with a volume average particle diameter of 12 μm. A conductive toner was obtained.

Example 2 Perylene PV Fast Red B 50 parts by weight (manufactured by Hoechst) Epoxy resin ERL4221 40 parts by weight (Un
ion Carbide Co.) Maleic anhydride
After mixing and dispersing 10 parts by weight in a kneader, the mixture was hardened by heating at 120° C. for 3 hours. The obtained cured product was crushed and classified to obtain fine particles for a core having a volume average particle diameter of about 2 μm.

The thus obtained core 5 parts by weight of vinyl carbazole/n-butyl methacrylate (same as in Example 1) and 95 parts by weight were heat-kneaded in a pressure kneader in the same manner as in Example 1, and then pulverized and classified to form volume-average particles. A photoconductive toner having a diameter of 13 μm was obtained.

Comparative example Peri L/:/PV Fist Red B
5 parts by weight of styrene-vinylidene chloride resin 5 parts by weight of toluene 90 tt parts were uniformly dispersed by 100H dispersion using a ball mill dispersion method. This dispersion was placed in a stainless steel vat and air-dried in a draft. This is further vacuum heated and dried, then crushed and
A photoconductive toner with a volume average particle diameter of 10 μm was obtained by classification. The photosensitivity of the photoconductive toner itself obtained in Examples 1 and 2 and the comparative example was measured by photocurrent under 1000 lux light irradiation. The ratio of the dark current value to the dark current value (the value of the current flowing when a voltage of 100 V was applied to the electrodes after toner was packed between interdigitated electrodes with a distance of 0.5 mm) was calculated. Also,
To evaluate the photosensitivity when a thin layer of several to ten or more layers is formed, a thin layer of photoconductive toner was actually formed on a transparent electrode, and an image was formed using the Sigerman method. The image quality of each image was evaluated. Further, the fixability of the photoconductive toner was evaluated by conducting a fixability test on the thus obtained toner image using a heat roll fixing device.

These results are shown in the table. Hereinafter, f: Us゛L As described above, the photoconductive toner according to the present invention has better image quality in a thin layer than conventional toners, and has excellent fixing properties, resulting in clear images. It was confirmed that

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a photoconductive toner according to the present invention. 1...Matrix body % consisting mainly of charge transporting substance
2: A core mainly made of a substance that generates electric charge by absorbing light.

Claims (2)

[Claims] (1) A photoconductive toner characterized in that a plurality of core bodies mainly composed of a substance that generates electric charges by light absorption are dispersed in a matrix composed of a charge-transporting substance in the form of domains. (2) The light absorption wavelength range of the matrix mainly composed of a charge-transporting substance does not overlap in the wavelength range of 200 to 900 nm with the light absorption wavelength range of the core body mainly composed of a substance that generates charges by light absorption. A photoconductive toner according to claim 1, characterized in that: