JP2833243B2 - Toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like.

[0002]

2. Description of the Related Art In electrophotography, a photoconductive material such as selenium is used as a photoreceptor, an electric latent image is formed by various methods, and toner is adhered to the latent image by a magnetic brush developing method or the like. In general, a method of visualizing the image is adopted. The toner used here has a positive or negative charge according to the polarity of the electrostatic latent image to be developed by a friction charging method. By the way, as a method of charging the developing toner, there is a method of controlling the charge using a binder resin which is a main component of the toner. However, when the charge is insufficient, or a polarity opposite to the original charge polarity of the binder resin is used. In the case where the colorant is charged, there is a method of giving the colorant a charge imparting ability. For example, there is a method of supplementing the charging ability by using carbon black having a PH corresponding to the charging polarity of the toner. PH7 for positively charged toner
The above basic carbon blacks may be used (see
JP-A-77732), acidic carbon black having a pH of 7 or less is used for the negatively charged toner, and a charge control agent is used to further increase the charging ability.

[0003]

In the above method, a basic carbon black is used for the positively charged toner. However, the surface of the carbon black has few oxygen-containing functional groups such as carboxyl groups and phenol groups. Since the dispersibility in the binder resin is poor, the blackness decreases. When using such a toner, in order to sufficiently produce the black color on the copy paper,
Conventionally, it has been necessary to maintain a high toner concentration in the developer. However, in this method, a load is applied not only to the carrier or the charging member but also to the toner itself, and there is a possibility that the deterioration of the developer is accelerated and the life is shortened. In addition, acidic carbon black is used for the negatively charged toner, and the surface thereof has a large amount of the oxygen-containing functional groups, so that the dispersibility in the binder resin is good, but water is easily adsorbed. In addition, there is a problem that the chargeability of the toner is reduced in a summer environment. Therefore, the present invention is intended to solve the above-mentioned problems and to provide a toner excellent in chargeability and environmental stability, can extend the life of the developer, and reduce background stains and the like. This makes it possible to secure a satisfactory image.

[0004]

Means for Solving the Problems The present invention provides at least:
A toner for developing an electrostatic image containing a binder resin and a colorant as main components, wherein carbon black having a pH of 5 or less and carbon black having a pH of 8 or more are used in combination as the colorant. This is an image developing toner.

The binder resins used in the toner of the present invention include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isobutylene, vinyl acetate, vinyl propionate and vinyl benzoate. Α─methylene aliphatics such as vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, ethyl methacrylate, butyl methacrylate and dodecyl methacrylate Monocarboxylic acid esters, vinyl methyl ether, vinyl ethyl ether, vinyl ether such as vinyl butyl ether, vinyl methyl ketone, vinyl hexyl ketone,
Homopolymers or copolymers such as vinyl ketones such as vinyl isopropenyl ketone can be exemplified. Particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, and styrene-methacrylic acid. Examples thereof include an alkyl copolymer, a styrene / acrylonitrile copolymer, a styrene / butadiene copolymer, a styrene / maleic anhydride copolymer, polyethylene, and polypropylene. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned.

As the colorant of the toner of the present invention, two kinds of carbon blacks having different PHs are used. That is, PH ≧
When the carbon black A of No. 8 and the carbon black B of PH ≦ 5 are used as a positively charged toner, the mixing ratio is preferably selected within a range of 1 ≦ A / B ≦ 5. When used as a negatively charged toner, the mixing ratio should be 0.2 ≦
It is preferable to select A / B ≦ 1. In the present invention, since the carbon black in the above combination is used, the charging ability of the carbon black is reduced. Therefore, it is preferable to add a charge control agent for the purpose of compensating the charging ability and increasing the charging ability of the toner. A quaternary ammonium salt type charge control agent for a positively charged toner, and a metal complex salt compound charge control agent having a salicylic acid ligand for a negatively charged toner are preferable from the viewpoints of charging ability and environmental stability.

The quaternary ammonium salt type charge control agent used in the present invention is a compound represented by the following general formulas (I) to (III), and a metal complex salt compound charge control agent having a salicylic acid ligand. Is a compound represented by the following general formula (V), but the present invention is not limited thereto. (Quaternary ammonium salt type charge control agent)

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Embedded image Specific examples of the compound represented by the above general formula (I) (I-
The following are 1) to (I-9).

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Embedded image Specific examples of the compound represented by the above general formula (II) (II
-1) to (II-2) are shown below.

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Embedded image Specific examples of the compound represented by the above general formula (III) (I
II-1) is mentioned below.

Embedded image Further, compounds (IV─1) to (IV-2) other than the above-mentioned general formulas which can be used in the present invention are exemplified below.

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Embedded image (Charge control agent for metal complex salt compound having salicylic acid ligand)

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[0008]

In the present invention, the above two different types of carbon blacks are used in combination as colorants to compensate for the disadvantages of each carbon black. That is, the basic carbon black that has been conventionally used for a positively charged toner has few oxygen-containing functional groups such as a carboxyl group and a phenol group on its surface, so that it has poor dispersibility in a binder resin and a poor blackness. However, the above-mentioned disadvantage was solved by using an acidic carbon black having excellent dispersibility in a binder resin because of having many oxygen-containing functional groups on the surface. The acidic carbon black used for negatively charged toners has a large amount of oxygen-containing functional groups on the surface and thus has good dispersibility in the binder resin. Although it has the disadvantage of lowering and increasing the environmental dependency, by using a combination of basic carbon black having a small number of oxygen-containing functional groups,
The above disadvantages have been eliminated. That is, in the present invention, carbon black A having PH ≧ 8 and carbon black B having PH ≦ 5 are used in combination, and when used as a positively charged toner, the mixing ratio is selected within the range of 1 ≦ A / B ≦ 5. Is preferred. A /
When B> 5, the blackness may be insufficient, and A /
In the case of B <1, the toner becomes insufficiently charged, which may cause background contamination. When used as a negatively charged toner, the mixing ratio is preferably selected within the range of 0.2 ≦ A / B ≦ 1. When A / B> 1, the charging of the toner may be insufficient, and when A / B <0.2, the environmental dependency may increase. Further, by simultaneously using two kinds of carbon blacks having different PHs, the dispersion diameter of the carbon black can be made large and uniform,
Even if the amount of carbon black is reduced, sufficient blackness can be obtained. Further, when a charge control agent is used, the effect of improving the dispersion of the charge control agent can be obtained.

[0009]

[Example 1]

(Production of toner) Styrene / butyl acrylate copolymer (80/20) 100 parts Carbon black A (Legal 330, PH8.5 manufactured by Cabot) 7 parts Carbon black B (BP-1300, PH2.5 manufactured by Cabot) 3 parts Low molecular weight polypropylene (Viscol 660P manufactured by Sanyo Chemical Co., Ltd.) 5 parts The above components are melt-kneaded with a Banbury mixer, cooled,
Finely pulverized by a jet mill and further classified finely pulverized product by a classifier, the average particle diameter D ₅₀ was obtained toner 11 [mu] m. (Manufacture of carrier) Styrene / butyl acrylate copolymer (80/20) 30 parts Magnetite (Toda Kogyo Co., Ltd., EPT-1000) 100 parts The above components were melt-kneaded with a pressure kneader, and further pulverized using a classifier. After classification, a carrier having an average particle size D ₅₀ of 50 μm was obtained. (Preparation of dry developer) For 100 parts of the above carrier,
3 parts of the above toner was mixed with a V blender to prepare a dry developer. Example 2 A dry developer was prepared in the same manner as in Example 1, except that 1 part of Bontron P # 51 manufactured by Orient Chemical Co., Ltd. was added as a charge control agent for the toner and melt-kneaded simultaneously with other toner components. . Example 3 A dry developer was prepared in the same manner as in Example 1, except that the carbon black A of the toner was changed to 8 parts and the carbon black B was changed to 2 parts.

Example 4 (Production of Toner) A toner was obtained in the same manner as in Example 1 except that the components of the toner were changed as follows. Polyester resin 100 parts Carbon black C (Legal 500R, PH8.0 manufactured by Cabot) 4 parts Carbon black D (Legal 400, PH4.5 manufactured by Cabot) 6 parts Low molecular weight polypropylene (Viscol 660P manufactured by Sanyo Chemical) 5 parts ( Production of carrier) 15 parts of methyl methacrylate / styrene / vinylpyrrolidone copolymer (78/20/2) were dissolved in 100 parts of toluene. The resulting solution was added to 2,000 parts of spherical ferrite having an average particle diameter of 100 μm, and coated with a vacuum kneader coater to obtain a carrier. (Preparation of dry developer) For 100 parts of the above carrier,
3 parts of the above toner was mixed with a V blender to prepare a dry developer. Example 5 Dry development was performed in the same manner as in Example 4 except that 1 part of Bontron E-84 manufactured by Orient Chemical Co., Ltd. was added as a charge control agent for the toner of Example 4 and melt-kneaded simultaneously with other toner components. An agent was prepared. Example 6 A dry developer was prepared in the same manner as in Example 5, except that the carbon black C of the toner was changed to 3 parts and the carbon black D was changed to 7 parts.

Comparative Example 1 A dry developer was prepared in the same manner as in Example 1, except that 10 parts of carbon black A was used and carbon black B was omitted. [Comparative Example 2] A dry developer was prepared in the same manner as in Example 4, except that carbon black C in the toner was omitted and carbon black D was changed to 10 parts.

[Evaluation of actual machine] An FX-5075 copier manufactured by Fuji Xerox Co., Ltd. was used for the developers of Examples 1 to 3 and Comparative Example 1, and a developer of Fuji Xerox was used for the developers of Examples 4 to 6 and Comparative Example 2. The actual machine evaluation was performed using an FX-5030 copier manufactured by Sharp Corporation. The results are shown in Table 1. Table 1
As is clear from the graph, the toners for developing electrostatic images of Examples are excellent in chargeability, environmental stability, and life.

[Table 1]

[0013]

The toner for developing electrostatic images of the present invention has a pH of
The use of a carbon black different in color and the use of a charge control agent makes it possible to ensure good chargeability, environmental stability, and high-quality image free of background contamination.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Ikutaro Nagatsuka 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside the Fujimatsu Rocks Takematsu Office (72) Inventor Ryuichi Kimura 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Takematsu In-house (56) References JP-A-53-33151 (JP, A) JP-A-2-296257 (JP, A) JP-A-60-138563 (JP, A) JP-A-4-199156 (JP, A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) G03G 9/09

Claims (1)

(57) [Claims] 1. An electrostatic image developing toner containing at least a binder resin and a colorant as main components, wherein the colorant includes carbon black having a pH of 5 or less and PH being 8 or less.
A toner for developing an electrostatic charge image, wherein the toner is used in combination with the above carbon black.