JP2589388B2 - Black photoconductive toner with photosensitivity in semiconductor laser wavelength range - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a black photoconductive 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.
A toner granulated by a pulverization method or a spray method,
That is, 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. In this method, the steps of transferring a toner image and fixing the transferred toner image on copy paper are sequentially performed.

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.

Recently, it has been proposed to shift the photosensitive region to infrared light by using zinc oxide as a photoconductive material and a cyanine dye as a sensitizer. Since the toner containing the resin is blue-green and not black, it is further considered to add a black pigment as a colorant. 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.
Therefore, as a colorant without light absorption at 780 nm to 850 nm, BA
The perylene black pigment and yellow, cyan, and magenta quinone dyes made by SF Co., Ltd. were added to add a quinone dye to some extent, but because inorganic photoconductive materials such as zinc oxide were white, However, satisfactory results have not yet been obtained as a factor that hinders blackening of the toner.

(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 780 nm color having a black tint while preventing a decrease in toner chargeability. An object of the present invention is to provide a black photoconductive toner having excellent photosensitivity to wavelengths in the vicinity.

(Means for Solving the Problems) The black photoconductive toner having photosensitivity in the semiconductor laser wavelength range according to the present invention includes a binder resin, light-colored zinc oxide colored with erythrosin B, and a semiconductor laser wavelength range. A sensitizing dye having absorption at a wavelength as an essential component, a perylene black pigment and a yellow having no functional group as a colorant,
It contains one or a mixture of quinone dyes comprising magenta and cyan color dyes, thereby achieving the above object.

The black photoconductive toner preferably contains both a magenta pigment.

(Preferred Embodiment) As the binder resin, a conventionally known resin is used, and examples thereof include a styrene-based polymer, a styrene-butadiene copolymer, a styrene-acrylonitrile copolymer, a styrene-maleic acid copolymer, and an acrylic resin. Polymer, 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, polystyrene, diallyl phthalate resin, silicone resin, ketone resin,
Various polymers such as polyvinyl butyral resin, polyether resin, and phenol resin are exemplified.

The colored photoconductive material used in the present invention is a light-colored inorganic photoconductive material colored with a sensitizing dye having an absorption in a visible wavelength range. The sensitizing dye having absorption at a wavelength in the visible region is a colored sensitizing dye, and examples thereof include erythrosin B, fluorescein, and bromophenol blue. In addition, the light-colored inorganic photoconductive material is a white to light-colored inorganic photoconductive material, and examples thereof include zinc oxide, titanium oxide, and the like. Zinc oxide is particularly preferably used. For example, when this zinc oxide is colored with erythrosin B, it becomes deep pink, when it is colored with fluorescein, it becomes yellow to flesh color, and when it is colored with bromophenol blue, it becomes light purple to blue. The photoconductive material may be colored with a plurality of sensitizing dyes. For example, when the photoconductive material is colored with three sensitizing dyes, the photoconductive material has a black tint. This conceals the white color of the inorganic photoconductive material. The added amount of the photoconductive material colored with the sensitizing dye is as follows: photoconductive material / binder resin = 1/1 to 5
/ 1 (weight ratio) is preferred, and particularly preferably 2/1 to 3/1 (weight ratio).

The mixed dye of the three colors is a mixture of a yellow quinone dye, a magenta quinone dye, and a cyan quinone dye, and each dye has a hydroxyl group, a carboxyl group, an amino group, a sulfoxyl group, etc. Those having no functional group (reactive group) are preferred.

The quinone dye as a black colorant is, for example, indanthrene yellow as a yellow quinone dye.
BY (Indanthrene Yellow BY) and the like. Examples of cyan quinone dyes include Alizarine Brilliant Pure Brue.
And magenta quinone dyes such as Indanthrene Red 5GK.
And the like.

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 the obtained toner has greatly reduced sensitivity. Never do. For example, a quinone dye
Dyes having a functional group such as Suprance Violet4BF and Anthrancene Blue SWGG have strong interaction with the photoconductive material and are adsorbed on the photoconductive material, thereby inhibiting the adsorption of sensitizing dyes such as cyanine dye. As a result, the light sensitivity of the toner is reduced.

In the present invention, one or more of these dyes are preferably added.For example, a black dye is obtained by mixing three color dyes, and a black color is obtained by adjusting the amount of the three colors. The color of the toner can be adjusted.

Examples of the perylene black pigment as a black colorant include perylene-3,4,9,10-tetracarboxylic diimide. These perylene black pigments may be used alone or in combination of two or more.

The perylene black pigment and the quinone dyes of the above three colors may be used alone or as a mixture, and the addition amount thereof is preferably 1 to 30% by weight based on the binder resin, and particularly preferably 5 to 30% by weight.
~ 15% by weight is preferred.

Cyanine dyes are preferably used as sensitizing dyes that absorb light in the semiconductor laser wavelength range used in the present invention. 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). Or a plurality of them may be used in combination. 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.

In addition, a quinacridone-based, rhodamine-based, thioindigo-based, or azo-based magenta pigment can be added to the toner of the present invention for the purpose of color correction. This addition amount is appropriately determined within a range where the chargeability of the toner does not decrease.

Further, in addition to the above-described components, the toner of the present invention may contain, if necessary, an auxiliary agent such as a known wax such as an offset inhibitor and a pressure fixing agent 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) In the toner of the present invention, the white color of the inorganic photoconductive material is concealed, so that the toner does not hinder the blackening of the toner. , A black toner having excellent light sensitivity can be obtained.

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

Example 1 Zinc oxide colored with erythrosin B, Grade # 2 (manufactured by Hakusui Chemical) 100 parts by weight styrene-acrylic resin, PA-525 (manufactured by Mitsui Toatsu Chemicals) 33 parts by weight perylene black pigment, Pailogen Black L0086: 1.5 parts by weight Quinone dye, TON109 (manufactured by Mitsui Toatsu Chemicals): 1.5 parts by weight Cyanine dye, NK3425 (Japan Photographic Pigment Research Institute): 0.1 parts by weight Troen: 1000 parts by weight The above mixture was dispersed and mixed. Thereafter, a black photoconductive toner having an average particle diameter of 10 to 11 μm was obtained by a spray drying method.

Example 2 Zinc oxide colored with erythrosin B, Grade # 2
A black photoconductive toner was obtained in the same manner as in Example 1 except that zinc oxide colored with fluorescein, Grade # 2 (manufactured by Shiromizu Chemical Co., Ltd.) was used instead of (made by Shimizu Chemical Co., Ltd.).

Example 3 Zinc Oxide Colored with Erythrosin B, Grade # 2
A black photoconductive toner was obtained in the same manner as in Example 1, except that zinc oxide colored with bromophenol blue, Grade # 2 (manufactured by Shiromizu Chemical Co., Ltd.) was used instead of (manufactured by Shimizu Chemical Co., Ltd.). Was.

Example 4 Zinc oxide colored with erythrosin B, Grade # 2
A black light was obtained in the same manner as in Example 1 except that erythrosin B, fluorescein, and zinc oxide colored with bromophenol blue, Grade # 2 (manufactured by Hakusui Chemical) were used instead of (manufactured by Hakusui Chemical). A conductive toner was obtained.

Example 5 A black photoconductive toner was obtained in the same manner as in Example 1 except that the perylene black pigment was not used.

Example 6 A black photoconductive toner was obtained in the same manner as in Example 1 except that no quinone dye was used.

Comparative Example 1 A black photoconductive toner was obtained in the same manner as in Example 1 except that an uncolored zinc oxide, Grade # 2 (manufactured by Shimizu Chemical Co., Ltd.) was used.

Next, the black photoconductive toner obtained in Examples 1 to 6 and Comparative Example 1 and a ferrite carrier were mixed and frictionally charged, and then charged into a magnetic brush developing device for an electrophotographic copying machine. A photoconductive toner was uniformly adhered on the substrate to form a toner layer. Next, the monochromatic light (780 nm) extracted from the monochromator is applied to this toner layer.
Was irradiated for 0.5 seconds, the surface potential before irradiation and the surface potential 1.0 seconds after irradiation were measured, and the attenuation rate of the surface potential (maximum surface potential attenuation 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 shown in Table 1, the light-colored inorganic photoconductive material is colored with a sensitizing dye, and blackened using the colored photoconductive material and a perylene black pigment and / or a three-color quinone dye. By doing so, it can be seen that the electrical characteristics are not significantly impaired as compared with a black photoconductive toner prepared using an uncolored photoconductive material. Further, when the toners obtained in Examples and Comparative Examples were visually observed, Examples 1 to
The toner of No. 6 had a black tint, while the toner of the comparative example was green.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-1-266554 (JP, A) JP-A-48-63727 (JP, A) JP-A-61-167954 (JP, A) JP-A 64-64 74555 (JP, A) JP-A-1-202760 (JP, A) JP-A-63-96666 (JP, A) JP-A-1-227162 (JP, A) JP-A-62-1753 (JP, A) JP-A-57-139144 (JP, A) JP-A-59-181361 (JP, A)

Claims (2)

(57) [Claims] An essential component is a binder resin, light-colored zinc oxide colored with erythrosin B, and a sensitizing dye having absorption in a wavelength range of a semiconductor laser, and a perylene black pigment and a functional group as colorants. One of the quinone dyes comprising yellow, magenta and cyan color dyes having no
A black photoconductive toner having photosensitivity in a semiconductor laser wavelength region containing a seed or a mixture thereof. 2. The black photoconductive toner according to claim 1, further comprising a magenta pigment.