JPH03107865A - Photoconductive toner and image forming device - Google Patents

Abstract

PURPOSE:To improve photoresponsiveness by making photoconductive inorganic pigment of porous microcrystal powder. CONSTITUTION:The photoconductive inorganic pigment is made of the porous microcrystal powder, and the specific surface of the pigment is 20 - 1,000m<2>/g and the oil absorption of the pigment is 50 - 400ml/100g. When the porous pigment having the large surface area and the high oil absorption is used, it is easy to form a structure in resin because of the high aggregation of the pigment, so that it is possible to form a conductive chain with a little additional quantity. Thus, the photoresponsiveness and fixation are improved with keeping electrostatic charging ability.

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.

14 Since the pigment is added in an excessive amount in order to exhibit a photoconductive function, the toner has poor charging properties and fixing properties.

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 porous microcrystalline powder.

In addition, as a microcrystalline powder, the specific surface area is 20~1゜000.
m2/g, oil absorption 50-400 m1/1
00g.

Further, the image forming apparatus is characterized in that it uses the photoconductive toner described above. It is also characterized by using a semiconductor laser as a light source.

[Function] In order to disperse a photoconductive pigment in a resin and make it exhibit conductivity, it is necessary to form a conductive chain with the pigment in the resin, and when used as a toner at the same time, it is necessary to form a conductive chain in the resin. If too much pigment is added to the toner, fixing properties and charging properties will be adversely affected.

When using a pigment that is porous, has a large surface area, and has a large oil absorption amount, it has a strong cohesive force and easily forms struts in the resin, making it possible to form a conductive chain with a small amount added. This makes it possible to produce a photoconductive toner with good photoresponsiveness and fixing properties while maintaining chargeability.

Furthermore, by configuring an image forming apparatus using the photoconductive toner described above, it is possible to perform printing with excellent color reproducibility. Furthermore, by selecting a sensitizing dye, it is possible to use a semiconductor laser, which reduces the cost of the device.

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

[Example code] 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. , azomethine is used. Examples of these types of dyes are Rose Bengal, Acridine Orange, Rhodamine B, Erythrosine,
Eosin, fluorescein, brilliant green,
There are crystal violets, etc.

The following can be used as the coloring agent.

Nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, pont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate,
Lamp black, oil black, azo oil black, rose bengal, crystal violet, rhodamine B. This time, we decided to use an azo metal-containing dye as the black colorant.

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, polyarylates 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 phototoner) according to the present invention are shown below.

Zinc oxide: 20 parts by weight Sensitizing dye: 0.02 parts by weight Ethyl alcohol: 40 parts by weight Since the sensitizing dye uses a semiconductor laser as a light source,
A cyanine dye with the following structure was used.

Sensitizing dye of Example 1 The following zinc oxides were used.

Specific surface area...100m2/g Oil absorption amount...160ml/100g 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...60 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 azo coupling, Me is Cr, x, Xs are long chain methyl groups, 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 way, the raw material solution was prepared to have a solid content of 5%, and a photoner of about 10 μm was prepared by spray drying.

Next, FIG. 1 schematically shows the process of an image forming apparatus using the photoconductive toner of the present invention. The basic configuration is drums,
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 formed of a dielectric material 9, and the inner conductive substrate 10 is grounded. While a developing electric field is being applied to the developer 1 triboelectrically charged by the two-component magnetic brush 2, an exposure system 3 irradiates the developer 1 with light to form an image. 1. Zinc oxide is sensitized by near-infrared rays using 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 11 to recover its resistance, and an image is formed on the paper by ordinary electrostatic transfer through plain paper 8 in a transfer section. Next, it is permanently fixed using a heat roll 6. The toner remaining on the drum is removed by a cleaning brush 7. When images were actually formed through this process, 300DP I
A printing speed of 20 PPM was obtained with a resolution of . 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 l Oe r g / c
Writing was performed using m2. In this method, development and exposure are performed simultaneously, increasing speed, and since only one layer is developed by charge injection, it is possible to print with clear images without background smearing. These printing results show that the phototoner exhibits photoresponsiveness with respect to the amount of inorganic pigment added, and the clear and reproducible printing is thought to be due to the small amount of added inorganic pigment. This shows that plain paper fixability and black printing accuracy are functioning as desired.

[Example 2] As the phototoner structure of the present invention, a double-structured microcapsule toner can be prepared in which the surface has a composition containing zinc oxide for photoresponsiveness, and the inner core contains an excess of resin to ensure fixability.

The composition and manufacturing method of the micro-force 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...20 parts by weight Cyanine dye...0.02 parts by weight Ethyl alcohol...100 parts by weight Butyral resin...80 parts by weight The same pigment as in Example 1 was used as the sensitizing dye.

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 this microcapsule toner was subjected to the process of Example 1, good printing was obtained. This indicates that insulation on the surface is ensured, triboelectric charging properties and transferability work as expected, and photoresponsiveness, fixing properties with inner core particles, and coloring properties function as designed.

[Example 3] Printing experiments were conducted using the micro-force self-adhesive toner of the present invention in which the amount of pigment added to the outer photosensitive layer was changed as follows. This ratio has a specific surface area of 1 for zinc oxide.
00m”7g, oil absorption 11160ml/100g
This is the value for the case of . Needless to say, the optimal ratio will change if the zinc oxide changes.

Table 1 As you can see from this table, the amount of zinc oxide pigment added is 2%.
Printing is possible at ~90%, and from the viewpoint of clarity and sensitivity, it is preferably 5% ~75%. 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.

[Example 4] In the photoner of the present invention, the results of a printing experiment in which the ratio of the amount of pigment added was changed in a normal dispersion type photoner will be shown.

In this case as well, the conditions for zinc oxide are the same as in Example 3.

Table 2 Table 3 Table 4 As can be seen from this table, the amount of zinc oxide pigment added is 0.
Printing is possible with a value of 2 to 5, and preferably 0.25 to 1 from the viewpoint of clarity and sensitivity. Within this range, the photoner 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 photoner of the present invention is functioning as designed.

[Example 5] The results of printing experiments in which the physical composition of the pigment in a normal dispersion type phototoner of the present invention was changed are shown.

In this case, a zinc oxide pigment/resin ratio of 1 was used.

As can be seen from this table, the specific surface area of zinc oxide pigment is 2.
Printing is possible at 0 m2/g and above, and the larger the better in terms of clarity and sensitivity.

Also, there is a balance between oil absorption and specific surface area.
400ml/100g is good in terms of pigment dispersibility and toner fixability on plain paper. 50ml/1
00g or less, the dispersibility in the resin is insufficient, and the
When the weight exceeds 00 ml/100 g, fixing performance must be reconsidered.

Although the embodiments have been described above, the process using the photoner 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, since the photoconductive inorganic pigment uses porous microcrystalline powder, it becomes easier to form conductive chains, and as this microcrystalline powder, Surface area 20-1,000 m2/g, oil absorption 1 50-400 m
By using 1/100 g, 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 a semiconductor laser with a small amount of light as a light source, and the initial cost of the image forming apparatus can be reduced.

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 provides an image This has the effect of making it possible to provide a compact and simple process device that can provide clear images with good reproducibility.

[Brief explanation of drawings]

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. 2. Two-component magnetic brush developer 3. Exposure system photoner corona transfer device Heat roll cleaning brush Plain paper corona charger and above

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 porous microcrystalline powder. (2) The microcrystalline powder used as a photoconductive inorganic pigment has a specific surface area of 20 to 1,000 m^2/g and an oil absorption of 50 to 50.
The photoconductive toner according to claim 1, wherein the photoconductive toner has a volume of 400 ml/100 g. (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.