JPH08123094A - Electrophotographic toner - Google Patents

Abstract

PURPOSE: To obtain an electrophotographic toner which has high safety and does not adversely affect the human body, environment, etc., by using edible dyestuff confirmed to have safety for use with food as a charge control agent. CONSTITUTION: This electrophotographic toner is prepd. by using the edible dyestuff as the charge control agent. The toner is composed by dispersing a coloring agent in particles consisting of resins for fixing, the edible dyestuff as the charge control agent and others, such as various additives. Various kinds of the edible dyestuff confirmed to have safety as foods are usable for the edible dyestuff used as the charge control agent. There is no possibility of impairing the color taste of the color toners if the edible dyestuff formed to meet the color toners of the toners is used as the charge control agent in the case of the color toners exclusive of black. Omission of other coloring agents is possible as well by commonly using the edible dyestuff as the coloring agent of the toners. In such a case, the safety is further improved and a reduction in cost is resulted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner, and more particularly to an electrophotographic toner which is highly safe and does not adversely affect people or the environment.

[0002]

2. Description of the Related Art With the recent improvement of environmental awareness, it is used in an image forming apparatus such as an electrostatic copying machine, a laser beam printer, a facsimile, etc. to which a so-called electrophotographic method is applied. With respect to the electrophotographic toners, the composition of the toner is required to be reviewed in order to reduce the safety thereof, particularly the influence on the human body and the environment.

An object of the present invention is to provide an electrophotographic toner which is highly safe and does not adversely affect the human body or the environment.

[0004]

Means and Actions for Solving the Problems The electrophotographic toner of the present invention for solving the above problems is characterized by using an edible dye as a charge control agent. According to the electrophotographic toner of the present invention having the above-mentioned constitution, since the food dye, which has been confirmed to be safe for food, is used as the charge control agent, it is highly safe.

As the above-mentioned food dyes, those having various tints can be used. Therefore, in the case of a color toner other than black, if a food dye that matches the color tone of the toner is used as a charge control agent, the color is changed. There is no risk of impairing the color of the toner. Therefore, the structure of the present invention can be suitably applied to toners of cyan, magenta, and yellow, which are used for full-color image formation, for example.

Further, it is possible to use the food dye as a colorant for the toner and omit the other colorants. In that case, there is an advantage that the safety is further improved and the cost is reduced. The present invention will be described below.
The toner for electrophotography of the present invention is constituted by dispersing a colorant, an edible dye as a charge control agent, and other various additives in particles made of a fixing resin, as in the conventional case.

Of these, various food dyes which have been confirmed to be safe for food use can be used as the food dye used as the charge control agent. Specific examples of food dyes include, but are not limited to, the followings. <Red> Edible Red No. 2 (Amaranth, CI No. 1
6185), edible red No. 3 (erythrosine, CIN
o. 45430), Edible Red No. 40 (Arula Red A
C, C.I. I. No. 16035), food red No. 102 (new coccin, CI No. 16255), food red No. 104 (phloxine, CI No. 4541).
0), Edible Red No. 105 (Rose Bengal, CIN)
o. 45440), food red No. 106 (acid red,
C. I. No. 45100). <Yellow> Edible Yellow No. 4 (Tartrazine, CI No.
19140), Edible Yellow No. 5 (Sunset Yellow FC
F, C. I. No. 15985). <Green> Edible Green No. 3 (First Green FCF,
C. I. No. 42053). <Blue> Edible Blue No. 1 (Brilliant Blue FCF,
C. I. No. 42090), Food Blue No. 2 (Indigo Carmine, CI No. 73015).

Since all such food dyes are water-soluble, in order to ensure the weather resistance of the electrophotographic toner, it is preferable to use them in the form of food lake which is made into a metal salt and adsorbed on the substrate. Aluminum is most preferable as a metal that forms a water-soluble food dye and a salt from the viewpoint of safety, but barium, calcium, iron, magnesium and the like can also be used. Further, examples of the substrate for adsorbing the metal salt include an adsorptive extender pigment such as aluminum hydroxide.

The above edible lake is almost insoluble in water, fats and oils and organic solvents, and is a fine particle having a primary particle size of 10 μm or less, which has high coloring property and is harder than the water-soluble edible raw material. It is also excellent. In addition, the edible lake mainly functions as a charge control agent having a negative polarity due to the chemical structure of the metal salt of the water-soluble edible pigment.

In the case of color toners, two or more of the above-mentioned food dyes such as food lakes can be used in combination depending on the tint. For example, when an edible lake is used as the edible pigment, in order to mix the two colors, the two edible lakes produced from the edible pigments of the respective colors may be blended in the toner. It is also possible to produce an edible lake having a color mixture of two colors by itself using an edible dye as a raw material and mix it with a toner.

The blending amount of the food dye such as food lake varies depending on the charge imparting performance due to the chemical structure of the food dye, but generally 0.5 to 20 parts by weight per 100 parts by weight of the fixing resin. It is preferably part by weight, more preferably 1 to 10 parts by weight. This value is the blending amount of the food dye when one color of food dye is used alone, and the total amount when the food dye of two or more colors is used in combination.

If the amount of the food dye blended is less than the above range, sufficient charge imparting performance may not be obtained. On the contrary, if the amount exceeds the above range, the image density may decrease. Further, when the amount of the food coloring compound exceeds the above range, the durability of the developer containing the toner of the present invention decreases,
As a result, the image density may be reduced.
Note that the decrease in the durability of the developer means that, for example, in a two-component system developer containing a magnetic carrier and a toner, a component of the toner such as an edible dye adheres to the surface of the magnetic carrier,
It means that the charging performance is deteriorated.

In addition to the blending amount, the dispersibility in the fixing resin is greatly related to the charge imparting performance of the food dye, as an important factor. That is, the more uniformly the food dye is dispersed in the fixing resin, the more uniform and stable the charging performance can be obtained. Therefore, for example, when using an edible lake as an edible pigment,
It is desirable to use an edible lake having a smaller particle size even in the range of μm or less, and at the time of producing an electrophotographic toner, the mixing conditions for premixing, kneading conditions and the like are appropriately set to form an edible lake. It is desirable to disperse the resin in the fixing resin as uniformly as possible.

The electrophotographic toner of the present invention can be constructed in the same manner as the conventional one except that the above-mentioned food dye such as food lake is used as a charge control agent. The fixing resin is not limited to this, and examples thereof include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, and styrene-butadiene copolymer. , Styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer) Coal, styrene-butyl acrylate copolymer, styrene-
Octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate) Copolymers, styrene-phenyl methacrylate copolymers, etc.), styrene-α-chloromethyl acrylate copolymers, styrene-acrylonitrile-acrylic acid ester copolymers and other styrene resins (including styrene or styrene substitutes) Homopolymer or copolymer),
Polyvinyl chloride, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-ethyl acrylate copolymer, polyvinyl butyral, ethylene-vinyl acetate copolymer,
Examples include rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, xylene resin, and polyamide resin, which may be used alone or in combination of two or more. To be

As the colorant, various conventionally known colorants can be used according to the tint of the toner. Further, in the present invention, as described above, the food dye serving as the charge control agent may also serve as a colorant, and the other colorants may be omitted. In the case of a black toner, examples of the colorant include acetylene black, carbon black, aniline black and the like.

Cyan, magenta and yellow pigments are used as full-color colorants. Of these, cyan colorants include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 16, C.I. I. Solvent Blue 55, C.I. I. Solvent Blue 70, C.I.
I. Direct Blue 25, C.I. I. Direct Blue 86 etc. can be mentioned.

Examples of magenta colorants include C.I. I. Pigment Red 49, C.I. I. Pigment Red 57, C.I.
I. Pigment Red 81, C.I. I. Pigment Red 122, C.I. I. Solvent Red 19, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52,
C. I. Basic Red 10, C.I. I. Examples include Disperse Red 15 and the like.

As yellow colorants, for example, C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 5, C.I.
I. Pigment Yellow 12, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I.
Acid Yellow 1, C.I. I. Solvent Yellow 2,
C. I. Solvent Yellow 6, C.I. I. Solvent Yellow 14, C.I. I. Solvent Yellow 15, C.I.
I. Solvent Yellow 16, C.I. I. Solvent Yellow 19, C.I. I. Solvent Yellow 21 and the like can be mentioned.

The amount of the colorant compounded is preferably 1 to 30 parts by weight, and 2 to 100 parts by weight of the fixing resin.
It is more preferably 20 parts by weight. A typical additive other than the food dye (charge control agent) and the colorant is a release agent (offset inhibitor) for imparting an offset preventing effect to the toner. Examples of the release agent (anti-offset agent) include aliphatic hydrocarbons, aliphatic metal salts, higher fatty acids, fatty acid esters or partially saponified products thereof, silicone oil, and various waxes. Among them, the weight average molecular weight is 1000 to 1000.
An aliphatic hydrocarbon of about 0 is preferable. Specifically, one or a combination of two or more of low molecular weight polypropylene, low molecular weight polyethylene, paraffin wax, a low molecular weight olefin polymer composed of olefin units having 4 or more carbon atoms is suitable.

The amount of the release agent compounded is preferably 0.1 to 8 parts by weight with respect to 100 parts by weight of the fixing resin, and is 0.1.
More preferably, it is 5 to 5 parts by weight. When magnetic powder is added, a magnetic toner as a one-component developer can be obtained. The magnetic substance is a substance that is strongly magnetized in that direction by a magnetic field, and is preferably chemically stable, and is preferably a fine powder having a particle size of 1 μm or less, particularly about 0.01 to 1 μm. Typical magnetic materials include iron oxides such as magnetite, hematite and ferrite, as well as metals such as iron, cobalt and nickel, or these metals,
Examples thereof include alloys with aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, etc., and mixtures thereof.

The mixing amount of the magnetic powder is 100% for the fixing resin.
It is preferably 20 to 300 parts by weight, more preferably 50 to 150 parts by weight, based on parts by weight. In addition, various additives such as a stabilizer may be blended in an appropriate ratio. The toner for electrophotography is a mixture obtained by homogeneously premixing the above components with a dry blender, a Henschel mixer, a ball mill, etc., and a kneading device such as a Banbury mixer, roll, uniaxial or biaxial extrusion kneader. It can be produced by uniformly melting and kneading the mixture, cooling the obtained kneaded product, pulverizing it, and classifying it if necessary. Alternatively, it can be produced by a suspension polymerization method or the like.

The particle size of the electrophotographic toner is 3 to 30 μm,
Particularly, it is preferably 4 to 20 μm, and 4 to 10 μm in the case of a toner having a small particle diameter for the purpose of improving the quality of a formed image.
The degree is preferred. An external additive may be added to the electrophotographic toner for the purpose of improving fluidity.

As the external additive, various conventionally known external additives such as inorganic fine particles and fluororesin particles can be used. Particularly, a silica-based surface treatment agent containing hydrophobic or hydrophilic silica fine particles, For example, ultrafine particulate anhydrous silica or colloidal silica is preferably used. The amount of the external additive to be added is not particularly limited and may be the same level as conventional. Specifically, 0.1 part of the external additive is added to 100 parts by weight of the toner particles.
It is preferable to externally add about 3.0 parts by weight, but in some cases, the external additive amount of the external additive may deviate from this range.

The toner composition for electrophotography of the present invention comprises a non-magnetic toner used alone as a non-magnetic one-component developer or a magnetic two-component developer together with a magnetic carrier, and a single magnetic one-component developer. It can be applied to various conventionally known toners such as a magnetic toner used as a toner or a photosensitive toner which itself has photosensitivity.

When used in a magnetic two-component developer, the toner concentration is preferably the same as in the conventional case, that is, about 2 to 15% by weight. In the case of a magnetic toner, a magnetic pigment may be mixed in the fixing resin. Further, in the case of a photosensitive toner, a photoconductive pigment and a cyanine dye as its sensitizing component may be mixed in the fixing resin.

[0026]

EXAMPLES The electrophotographic toner of the present invention will be described below based on Examples and Comparative Examples. Example 1 Styrene-acrylic resin 4000 as a fixing resin
Parts by weight, 400 parts by weight of carbon black as a colorant, and edible yellow as a charge control agent for controlling negative charge 5
60 parts by weight of No. aluminum rake and 112 parts by weight of polypropylene wax as a release agent were mixed, melt-kneaded, and then pulverized and classified to produce toner particles having an average particle diameter of 10 μm.

Then, 100 parts by weight of the toner particles were sprinkled with 0.3 part by weight of hydrophobic silica as an external additive to produce a black electrophotographic toner. Example 2 A black electrophotographic toner was manufactured in the same manner as in Example 1 except that 60 parts by weight of food blue No. 2 aluminum lake was used as the charge control agent for controlling the negative charge. Comparative Example 1 As a charge control agent for negative charge control, Spyron Black T
A black electrophotographic toner was manufactured in the same manner as in Example 1 except that 60 parts by weight of RH was used.

The following tests were conducted on the electrophotographic toners of the above Examples and Comparative Examples to evaluate the characteristics thereof. Electrical Property Test Conductivity (S / c) of the electrophotographic toners of Examples and Comparative Examples
m), dielectric constant, dielectric loss tangent tan δ and relaxation time (seconds)
Was measured using the measuring device shown in FIG. The results are shown in Table 1.
Shown in

The measuring apparatus shown in FIG. 1 has a cylindrical shield case 11 in which cylindrical electrodes 12 and 13 with flanges are provided.
And the ring body 14 are electrically isolated from each other via an insulating ring 15, the cylindrical electrodes 12 and 13 are connected to an electrical characteristic measuring instrument 16, and the ring body 14 is grounded. Has been done. In this measuring device, a powdery sample S is filled in a space formed by the cylindrical electrodes 12 and 13 and the ring body 14, and the upper cylindrical electrode 12 is moved downward as shown by an arrow in the figure. While pressing the sample S to compress the sample S, both the cylindrical electrodes 12, 13 are pressed.
In the meantime, an AC voltage having a predetermined frequency (100 kHz in the case of relaxation time) is applied from the electrical characteristic measuring instrument 16 to apply electrical characteristics (conductivity, permittivity, dielectric loss tangent tan of the sample S in the compressed state.
δ and relaxation time) are measured. As the electric characteristic measuring device 16, an impedance analyzer manufactured by Yokogawa Hewlett-Packard Co. is preferably used.

[0030]

[Table 1]

Charging Rising Characteristic Test The electrophotographic toners of Examples and Comparative Examples were mixed with a ferrite carrier to prepare a two-component developer having a toner concentration of 3%, which was made into a polypropylene container (poly container). , Content volume 3 ml), and allowed to stand in the working environment for 1 day for humidity control. Next, put this plastic container into a mini bottle (content volume: 300 ml), and rotate the mini bottle at 100 rpm.
I rotated it. Then, after rotating a predetermined number of times, using the total amount of the sample in the poly container, the rising charge amount (μC
/ G) was measured. Table 2 shows the results.

[0032]

[Table 2]

Actual machine test The two-component developer having a toner concentration of 3% used in the above charging rising characteristic test was applied to an electrostatic copying machine (D manufactured by Mita Kogyo Co., Ltd.).
C-4655), three black-and-white originals are copied, and the image densities of the front end portion, the central portion, and the rear end portion of each image and the fog density of the blank portion of each of the above-mentioned portions are measured by a reflection densitometer ( It was measured using TC-6D manufactured by Tokyo Denshoku Co., Ltd.).
The image density results are shown in Table 3, and the fog density results are shown in Table 4.

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

As described above in detail, according to the present invention, it is possible to obtain the electrophotographic toner which is highly safe and has no influence on the human body or environment.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a measuring device for evaluating electric characteristics of an electrophotographic toner.

Claims (1)

[Claims] 1. An electrophotographic toner comprising an edible dye as a charge control agent.