JPH02298955A - Photoconductive toner and image forming device - Google Patents

Abstract

PURPOSE:To exhibit photoresponsiveness with a smaller amt. of the pigment to be added by specifying the fiber diameter and fiber length of the fine crystal powder to be used as an inorg. pigment of the photoconductive toner consisting of at least the photoconductive inorg. pigment and binder resin. CONSTITUTION:The photoconductive pigment, a sensitizer, resin for binding and fixing, and a coloring agent are basically used. Zinc oxide, titanium oxide, cadmium sulfide, alpha-silicon, etc., are used as the pigment. The fiber diameter of the fine crystal powder is specified to 0.005 to 1.0mum and the fiber length to 0.5 to 5mum. The sensitizer is selected as desired by a photoconductive material and photosensitive wavelength region and, for example, a triphenyl methane dye, monomethyne cyanine, styryl dye, etc., are used. Alloy dyes of an azo system are used for the black coloring agent and insulating thermoplastic resins are adequate as the resin for binding and fixing, for which acrylic resins, such as, for example, polyacrylate and polymethacrylate, polystyrene and polyvinyl chloride are used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus using photoconductive toner.

[Prior Art] As an image forming apparatus using conventional photoconductive toner,
When printing in black, for example, inorganic materials such as dye-sensitized Z n O and dye-sensitized TiO2, or organic photoconductors such as phthalocyanine, quinacridone, and benzidine are used as photoconductive agents to print cyan, magenta, and yellow. Pigmented three-color mixed systems have been used. Still another method has been to use a toner in which the above photoconductive agent is mixed with a black colorant such as carbon black. In this case, dye-sensitized ZnO is often used as the photoconductive agent. In addition, as an example of a process using them, JP-A-60-
There was one shown in 31150.

A visible light source has been used as a light source for conventional image forming apparatuses using photoconductive toner. As an image forming apparatus using a semiconductor laser, there is an image forming apparatus disclosed in Japanese Patent Application No. 63-289094 that uses a photoconductive toner.

[Problems to be Solved by the Invention] However, the following problems have been pointed out in conventional photoconductive toners and image forming apparatuses using photoconductive toners, and solutions are desired.

1. The toner has poor charging and fixing properties because the amount of pigment added is excessive in order to express the photoconductive function.

2. Since the inorganic pigment used itself has a color, if the amount added is large, the color tone and color reproducibility of the toner will deteriorate.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned problems, and its purpose is to have sensitivity in the near-infrared region, maintain the chargeability and sensitivity of photoconductive toner, and improve fixing properties. This makes it possible to obtain clear black images with good reproducibility.

[Means for Solving the Problems] The photoconductive toner of the present invention is characterized in that the photoconductive inorganic pigment is a microcrystalline powder having an acicular structure. In addition, as a microcrystalline powder, the fiber diameter is 0°005μm to 0.1μm.
m1 fiber length is 0. It is characterized by having a diameter of 5 μm to 5 μm.

Further, the image forming apparatus is characterized in that it uses the above photoconductive toner and uses a semiconductor laser as a light source.

[Function] Photoresponse in the case of a pigment-dispersed type photoconductive toner is generally expressed by the photoconductive pigment forming a chain in the toner resin, and the generated carrier traveling through the chain and running through the toner. It is considered. Therefore, the pigment contained in the toner needs to be added in a large amount to reach a level that forms chains.

However, when a toner with such a configuration is used, problems such as those pointed out in the above-mentioned [Problems to be Solved by the Invention] arise, and the toner is not practical.

In the present invention, by using a needle-like substance as a photoconductive pigment, the probability of contact between the pigments is increased, and the formation of chains in the toner becomes possible with a small amount added.

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

[Example] The composition of the photoconductive toner of the present invention is shown below.

Basically, photoconductive pigments, sensitizers, binding and fixing resins, and colorants are used.

The following photoconductive pigments are used.

Zinc oxide, titanium oxide, zinc sulfide, selenium, cadmium sulfide, α-silicon.

Any dye can be selected as the sensitizer depending on the photoconductive material and the sensitive wavelength range. For example, triphenylmethane dye, diallylmethane dye, monomethine cyanine, trimethine cyanine, pentamethine cyanine, heptamethine cyanine, styryl dye, Oxonol, merocyanine, complex cyanine, azenium dye, azo dye, anthraquinone dye, indigo dye, vinylene dye, and azomethine are used. Examples of these types of dyes include rose bengal, acridine orange, rhodamine B, erythrosin, eosin, fluorescein, brilliant green, crystal violet, and the like.

It was decided to use an azo alloy dye as the black coloring agent.

Known insulating thermoplastic resins can be used as the binding and fixing resin, including acrylic resins such as polyacrylate and polymethacrylate, and copolymers thereof;
Styrene resins such as polystyrene and poly-1-methylstyrene and their copolymers, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride, polyester resins and their copolymers, polycarbonate resins, cellulose resins, Polyarylate resins can be used alone or in combination.

Specific examples of the present invention are shown below, but it goes without saying that the present invention is not limited thereto.

[Example 1] The composition and manufacturing method of the photoconductive toner (hereinafter referred to as photoner) shown in the present invention are shown below.

Zinc oxide: 40 parts by weight Sensitizing dye: 0.04 parts by weight Ethyl alcohol: 80 parts by weight Since the sensitizing dye uses a semiconductor laser as a light source,
A cyanine dye with the following structure was used.

The particle size of zinc oxide is 0.01μm in fiber diameter, 1a fiber length 1
μm needle-shaped material was used.

The above materials were mixed and uniformly dispersed and adsorbed using ultrasonic waves.

After adsorption, the solvent ethyl alcohol is removed by centrifugation to obtain dried dye-adsorbed zinc oxide.

Next, dissolve the following materials in methyl ethyl ketone solvent,
A resin colored solution was prepared.

Acrylic resin...40 parts by weight Black dye-1...20 parts by weight Black dye-1 has the property of transmitting near infrared light and is the second
As shown in the figure, it has a naphthalene ring and an azo coupling, Me is Cr, Xi, X3 is a long chain methyl group, X2. The one in which X4 was a long-chain ethyl group was used.

The above-mentioned dye-adsorbed zinc oxide is added to this solution, and further subjected to ultrasonic dispersion so that it is uniformly dispersed in the resin. In this manner, the raw material solution was prepared to have a solid content of 5%, and a phototoner having a thickness of approximately 10 μm was prepared by spray drying.

Next, FIG. 1 shows an outline of the process of an image forming apparatus using the photoconductive toner of the present invention. The basic configuration is a drum,
Consists of a two-component developer, writing optical system, corona transfer device, heat roll, and cleaning brush.

Next, the process will be explained.The drum surface is made of a dielectric material, and the inner conductive substrate is grounded. While a developing electric field is being applied by the two-component magnetic brush 2, the exposure system 3 irradiates light to form an image.Since the zinc oxide is sensitized to near-infrared rays by a sensitizing dye, an inexpensive semiconductor laser can be used as the light source. . When irradiated with light, only the conductive toner is injected with charge and further adhered to the dielectric surface. The developed conductive toner is irradiated with corona by a corona charger 12 to recover its resistance, and in the transfer section, it is passed through plain paper 8 and permanently fixed by a zero-order heat roll 6 that forms an image on the paper by ordinary electrostatic transfer. When an image was actually formed through a zero-line process in which the toner remaining on the drum was removed by the cleaning brush 7, a printing speed of 20 PPM was obtained at a resolution of 300 DPI. For the black solid image, O and D values of 1.5 or more were ensured. In addition, good images were obtained with good reproducibility in 10,000 printing tests. The light amount of the exposure system at this time is 10er
Writing was performed in g/cm2. With this method, development and exposure are performed simultaneously, increasing speed, and because only one layer of development is performed by charge injection, it is possible to print with sharp images without background smearing. These printing results are due to the photoresponsiveness of the photoner despite the 1:1 ratio of inorganic pigment to resin, and clear and reproducible printing is due to the small ratio of addition. This indicates that the toner's fixability on plain paper and the black printing temperature are functioning as desired.

[Example 2] Printing experiments were conducted using the same dispersion type photoner as in Example 1, with the particle size of the inorganic pigments contained changed as follows. The amount of pigment added was 1:1 with respect to the resin.

Table 1 As can be seen from this table, the smaller the spherical particle size, the easier it is to form a chain, and the more acicular, the more photoresponsiveness is possible with a smaller amount added.

[Example 3] As the phototoner structure of the present invention, a double-structured microcapsule toner can be prepared in which the surface has an excess of zinc oxide for photoresponsiveness, and the inner core has an excess of resin to ensure fixability.

The composition and manufacturing method of Micro Cub Self Toner are shown below.

First, using styrene particles with a particle size of 10 μm, black dye-
The particles are directly stained in the alcohol solution of 1 and used as inner core particles.

Next, prepare the following solution.

Zinc oxide: 50 parts by weight Cyanine dye: 0.05 parts by weight Ethyl alcohol: 100 parts by weight ff1fi butyral resin: 50 parts by weight Zinc oxide and sensitizing dye used as in Example 1 there was.

First, the above materials were mixed except for the resin, and uniformly dispersed and adsorbed using ultrasonic waves.

Next, a resin is added to this dispersion liquid and subjected to ultrasonic dispersion in the same manner to prepare a zinc oxide dispersed resin solution. Furthermore, inner core particles are added to this resin solution and subsequently uniformly dispersed using ultrasonic waves. In this way, the raw material solution was prepared to have a solid content of 10%, and a phototoner whose surface was coated by a spray drying method was prepared. Approximately 1 μm according to electron microscope observation
It was confirmed that the zinc oxide dispersed film was coated with a thickness of .

When the process of Example 1 was performed using this micro-force self-adhesive toner, good printing was obtained. Since the photosensitive area of this photo toner is limited to only the surface, the amount of pigment added is even smaller than the total toner, and these results indicate that it fixes well on plain paper and has good color reproducibility. .

[Example 4] The results of a printing experiment in which the composition ratio of pigment/binder resin was changed in a normal dispersion type phototoner of the present invention will be shown.

Table 2 As can be seen from this table, printing is possible with a zinc oxide pigment/binder resin ratio of 0.2 to 5, and from the viewpoint of clarity and sensitivity, it is preferable to set the ratio to be 0.25 to 1. be. Within this range, the phototoner of the present invention can ensure chargeability, exhibit photoresponsiveness, have good fixing properties, and print with clear color tones and good reproducibility. This shows that the phototoner of the present invention is functioning as designed.

[Example 5] Printing experiments were conducted using the micro-force self-adjusting toner of the present invention in which the pigment/binder resin composition ratio of the outer shell photosensitive layer was changed as follows.

Table 3 As can be seen from this table, printing is possible with a zinc oxide pigment/binder resin ratio of 0.2 to 20, and from the viewpoint of clarity and sensitivity, it is preferably 0.2 to 20. It is appropriate to set it to 5-5. In this range, the photoner of the present invention exhibits photoresponsiveness while ensuring insulation on the surface, has good fixing properties on plain paper, and is capable of printing with clear color tones and good reproducibility. indicates that the phototoner of the present invention is functioning as designed.

Although the embodiments have been described above, the process using the photo toner of the present invention is applicable not only to the above embodiments but also to all processes using photoconductive toner.

[Effects of the Invention] As described above, according to the present invention, the photoconductive inorganic pigment is a microcrystalline powder having an acicular structure, and this microcrystalline powder has a fiber diameter of 0.005 μm to 0.1 μm, By using fibers with a fiber length of 0.5 μm to 5 μm, it became possible to exhibit photoresponsiveness with a small amount of pigment added.

Furthermore, an image forming apparatus using the photoconductive toner described above can now use an inexpensive semiconductor laser as a light source.

If an image forming apparatus using the photoconductive toner according to the present invention is used, it has sensitivity in the near-infrared region, maintains the chargeability and sensitivity of the photoconductive toner, has excellent fixing properties, and has black color. The present invention has the effect of making it possible to provide a low-cost device with a small and simple process that can provide clear images with good reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a process using the image forming apparatus of the present invention. FIG. 2 is a diagram showing the composition of the black dye used in the photoconductive toner of the present invention. FIG. 3 is a diagram showing an example of the cross-sectional structure of the photoconductive toner of the present invention. 1, conductive drum 2, two-component magnetic brush developer 3, exposure system 4, photoner 5. Intermediate transfer device 6, corona transfer device 7, heat roll 8, cleaning brush 9, plain paper 10, dielectric substrate 11, conductive substrate 12, corona charger 13, photoconductive inorganic pigment Applicant: Seiko Epson Corporation Agent Person Patent attorney Kizobe Suzuki (1 person) Φ Figure 1

Claims (4)

[Claims] (1) A photoconductive toner comprising at least a photoconductive inorganic pigment and a binder resin, wherein the photoconductive inorganic pigment is a microcrystalline powder having an acicular structure. (2) Microcrystalline powder used as a photoconductive inorganic pigment with a fiber diameter of 0.005 μm to 0.1 μm and a fiber length of 0.5
2. The photoconductive toner according to claim 1, wherein the photoconductive toner has a particle diameter of .mu.m to 5 .mu.m. (3) An image forming apparatus using the photoconductive toner according to claim 1. (4) The image forming apparatus according to claim 3, wherein a semiconductor laser is used as the light source.