JPH11272016A - Electrophotographic toner - Google Patents

Abstract

(57) [Summary] [Problem] With the conventional technology, it is difficult to obtain an image having a stable image density, and there are some with fogging and toner scattering, and the charge amount of toner is adjusted according to each copying machine. There were difficulties such as doing. SOLUTION: The present invention mainly comprises a binder resin, a colorant, an azo metal compound and a triphenylmethane compound, and the content ratio of the azo metal compound to the triphenylmethane compound is 3: 3 by weight. 97 to 97: 3 and an electrophotographic toner having a volume resistance of 3 × 10 ¹⁰ to 15 × 10 ¹⁰ Ωcm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner used in an image forming apparatus such as a copying machine and a printer.

[0002]

2. Description of the Related Art At present, various types of copiers and printers are widely marketed, with various types of photoreceptors having a printing speed of about 3 to 100 sheets / min. The electrophotographic toner (hereinafter abbreviated as “toner”) to be used is designed and designed for each copying machine. An important factor in prescribing and designing the toner used in such various copying machines is to provide the toner with an appropriate charge amount.

Conventionally, the adjustment of the charge amount has been performed by adjusting the resistance between the toner and the carrier. However, the charge amount of the toner and the carrier varies depending on the environment in which the copying machine is placed, and in a high-temperature and high-humidity environment, when the resistance of the toner and the carrier is low, the charge amount of the toner is remarkably reduced, and ground fog occurs. Had a problem. In addition, when the resistance of the toner and the carrier is high, the charge amount under a low-temperature and low-humidity environment increases greatly, and the image density decreases.

Further, a method of adjusting the charge amount of the toner with an external additive such as hydrophobic silica, titanium oxide, and alumina has been proposed. However, when the amount of the external additive increases, the toner charge amount due to a change in temperature and humidity is increased. And the image density is difficult to stabilize. If the change is small, the storage stability deteriorates.

Although the charge amount of the toner can be adjusted by a carrier coating agent such as a silicone resin or an acrylic resin,
The carrier coating agent was peeled off due to toner fusion to the carrier surface or insufficient strength of the coating agent, causing a problem. In addition, the adjustment with the charge control agent leads to an increase in toner scattering because uncharged toner particles tend to be generated when the amount is small, and the toner resistance is likely to decrease when the amount is large, leading to ground fog. Was.

Conventionally, the charge amount of the toner has been adjusted according to each copying machine while adjusting these conditions. However, as described above, it is difficult to adjust the toner charge because of the respective problems. Had. INDUSTRIAL APPLICABILITY The present invention provides an electrophotographic toner which can be used in both a copier and the like using a positively and negatively charged photoconductor and has a stable charge amount capable of printing many sheets over a long period of time. The purpose is to:

[0007]

The invention of claim 1 comprises a binder resin, a colorant, an azo-based metal compound and a triphenylmethane-based compound as main components, and comprises an azo-based metal compound and a triphenylmethane-based compound. Content ratio is 3: 97 ~ by weight
97: 3, and the volume resistance is 3 × 10 ¹⁰ to 15 × 10 ¹⁰
Ωcm, wherein the total content of the azo metal compound and the triphenylmethane compound is 0.5 to 3 in the toner.
2. The electrophotographic toner according to claim 1, wherein the toner has a volume average particle diameter of 6 to 9 μm and a number particle diameter of 5 μm or less.
5 to 50% and a volume particle diameter of 16 μm or more are 0 to 3
The electrophotographic toner according to claim 1, which has a particle size distribution of 0.5% to 2%.
2. The electrophotographic toner according to claim 1, wherein 0.5% by weight and magnetite are attached to the surface at 0.5 to 2% by weight.

The materials constituting the toner of the present invention are as follows. <Binder resin> The binder resin is a polystyrene resin, a polyacrylate resin, a styrene-acrylate copolymer resin, a styrene-methacrylate copolymer resin, polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride. , A phenol resin, an epoxy resin, a polyester resin, or the like. The binder resin preferably has a melting start temperature as low as possible, particularly for the purpose of improving the fixing performance of the toner, and a resin having a high glass transition point, for the purpose of improving storage stability.

<Colorant> The colorant is carbon black,
Nigrosine dye, aniline blue, coco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, etc. are used alone or in combination. . The coloring agent needs to have a sufficient content of a coloring agent to form a visible image having a sufficient image density, and usually contains 1 to 2 parts by weight based on 100 parts by weight of the binder resin.
It is preferable that it is contained at a ratio of about 0 parts by weight.

<Azo-based metal compound> The azo-based metal compound used in the present invention has a chemical structure represented by the following general formula (1), specifically, a compound represented by the following chemical formula (2) or (7): 8, the structural formula shown in Chemical formula 9 is applied.

[0011]

Embedded image

[0012]

Embedded image

[0013]

Embedded image

[0014]

Embedded image

[0015]

Embedded image

[0016]

Embedded image

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image

<Triphenylmethane-based compound> The triphenylmethane-based compound used in the present invention has a chemical structure represented by the general formula shown in Chemical formula (10).
The structural formula shown below applies.

[0021]

Embedded image

[0022]

Embedded image

[0023]

Embedded image

[0024]

Embedded image

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image

The operation of the present invention will be described below. In the present invention, the content ratio of the azo metal compound to the triphenylmethane compound must be 3:97 to 97: 3 by weight. When the content ratio of the azo-based metal compound or the triphenylmethane-based compound is less than 3 by weight, the charge amount is not stable when a large number of sheets are printed, and an image having a reduced image density and a lot of background fog is obtained.

Further, the total content of the azo metal compound and the triphenylmethane compound is preferably 0.5 to 3% by weight in the toner. If the total content is less than 0.5 part by weight, the distribution of the charge amount among the individual toner particles will vary, and the background fog and toner scattering will easily occur. Also,
When the amount is more than 3 parts by weight, the volume resistance of the toner is apt to be reduced, and as a result, the occurrence of background fog and an increase in toner consumption are apt to occur.

<Other Additives> The toner of the present invention comprises:
The binder resin, the colorant, the azo-based metal compound and the triphenylmethane-based compound are the main components. In addition to these main components, the following materials are appropriately added.

Wax A wax is added to lower the melting start temperature of the toner and improve the low-temperature fixability. Examples of the synthetic wax include a polypropylene wax and a Fischer-Tropsch wax. Examples include paraffin wax, microcrystalline wax, petrotam and the like. Other waxes include carnauba wax, rice wax,
Natural waxes such as candelilla wax, oil-based synthetic waxes and the like are used.

Release Agent The release agent is added in order to ensure the releasability between the fixing heat roll and the toner, and low molecular weight polypropylene, low molecular weight polyethylene or the like is used.

・ Magnetic powder

External Additives External additives are added to control the fluidity, chargeability, cleaning properties, storage stability, etc. of the toner.
Magnetite, titanium oxide, alumina, various types of resin fine particles, and the like are used. Among them, hydrophobic silica is 0.1%.
Preferably, 5 to 2% by weight and magnetite are attached to the surface at 0.5 to 2% by weight.

When the hydrophobic silica content is less than 0.5% by weight, a part of the hydrophobic silica is buried in the toner particles by continuous printing, so that the fluidity and the chargeability are liable to decrease, and the durability cannot be obtained. If the content is more than 2% by weight, a part of the hydrophobic silica is released from the toner and adheres to the surface of the photoreceptor, so that the image is easily deteriorated. By attaching magnetite to the toner surface, the volume resistance of the toner can be appropriately adjusted, and the durability is improved.

In the present invention, the volume average particle diameter is 6 to 9
μm and having a number particle size of 5 μm or less
50%, volume average particle diameter of 16 μm or more is 0 to 3%
The particle size distribution is selected as follows.
If the volume average particle diameter of the toner is 6 to 9 μm, a high-quality image can be obtained. If the volume average particle diameter is out of this range, the image quality is rather poor, and the number particle diameter of all particles is 5 μm.
It is preferable to obtain a particle size distribution of 15 to 50% of the following particles, and a particle size distribution of 0 to 3% for a particle having a volume particle diameter of 16 μm or more of all particles to obtain higher image quality, and more than 3%. Does not improve image quality.

The toner of the present invention may be produced by a process in which the above-mentioned materials are melted and kneaded, then pulverized and classified, or may be produced by a polymerization method. The toner of the present invention is mixed with a carrier such as ferrite powder, iron powder or glass beads to form a two-component developer, or used as it is as a one-component developer.

The volume resistivity of the toner obtained by the present invention is 3 × 10 ¹⁰ to 15 × 10 ¹⁰ Ωcm. If the volume resistivity of the toner is less than 3 × 10 ¹⁰ Ωcm, the charge tends to leak and the background fogging becomes a problem. If the volume resistance is larger than 15 × 10 ¹⁰ Ωcm, the charge leakage is too small to increase the charge amount and deteriorate the developability. As a result, the image density decreases. The volume resistance of the toner in this case is measured as follows. That is, the toner is formed into a pellet by a press at a pressure of 500 g / cm ² , and a voltage is applied to the pellet to determine the conductance of the pellet. From the conductance, the volume resistance is determined by the following equation.

Ρ = 1 / G × S / d, where ρ: volume resistance S: effective electrode area d: thickness of pellet G: conductance

The electrophotographic toner of the present invention comprises a binder resin,
In addition to the colorant, the amount of the azo metal compound and the triphenylmethane compound and the total content are adjusted to control the amount of charge to control the charge amount, such as copying machines using positive and negative charge photosensitive members. Apply to both. Conventionally, in the case of negatively charged toner,
A negatively chargeable charge control agent is contained alone, and the content of the charge control agent is adjusted. However, when the content is small, the content of the charge control agent tends to be different between the toner particles or on the toner surface, which causes ground fogging and toner scattering.

Therefore, in the present invention, in the case of a negatively charged toner, the azo-based metal compound is contained in a certain amount, while the content of the triphenylmethane-based compound is adjusted to adjust the charge amount. Therefore, the negative charge amount of each toner particle does not change, and the charge amount of the entire toner can be adjusted by absorbing the negative charge by the triphenylmethane compound.
As a result, the charge amount can be adjusted while keeping the chargeability between each toner particle and on the toner particle surface constant, so that a toner having a stable charge amount can be obtained, and a practically sufficient image density and less background fog are obtained. Many images can be obtained.
In the case of a positively charged toner, on the contrary, the positive chargeability can be maintained with a triphenylmethane compound and the overall positive charge can be adjusted by the content of the azo metal compound.

[0042]

Next, the present invention will be described in more detail with reference to the following embodiments. However, the toner of the present invention is not limited to these embodiments. Hereinafter, parts are parts by weight.

Example 1 91.8 parts of styrene-acrylic acid ester copolymer (trade name: CPR-100, manufactured by Mitsui Chemicals) 8 parts of carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Corporation) Azo-based metal compound 2) 1 part triphenylmethane compound (Chemical formula 12) 0.2 part Low molecular weight polypropylene 2 parts (Viscol 330P manufactured by Sanyo Chemical Industries, Ltd.)

The above-mentioned raw materials were mixed by a super mixer, kneaded by hot melt in a twin-screw kneader, pulverized by a jet mill, and then classified by a dry air classifier to obtain a volume average particle diameter of 8 μm.
20% of all particles have a number particle size of 5 μm or less
In addition, particles having a volume particle diameter of 16 μm or more in all particles obtained particles having a particle diameter distribution of 2%. Next, the particles 9
In a Henschel mixer, 8.2% by weight, 0.8% by weight of hydrophobic silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) and 1.0% by weight of magnetite (BL-500, manufactured by Titanium Industry Co., Ltd.) were added. After mixing for 1 minute, the toner of the present invention was obtained. The volume resistance of this toner is 7 × 10 ¹⁰ Ωcm
Wherein the content ratio of the azo metal compound to the triphenylmethane compound is 83:17 by weight, and the total content of the azo metal compound and the triphenylmethane compound is 1.26 in the toner. % By weight.

Example 2 The procedure of Example 1 was repeated except that 4 parts of carbon black, 2.5 parts of the azo metal compound (Chemical Formula 2) and 0.3 part of the triphenylmethane compound (Chemical Formula 12) were used. Thus, the toner of the present invention was obtained. The volume resistance of this toner is 12 × 10
¹⁰ Ωcm, the content ratio of the azo metal compound to the triphenylmethane compound is 89:11 by weight, and the total content of the azo metal compound and the triphenylmethane compound is 2% in the toner. 0.9% by weight.

Example 3 A toner of the present invention was obtained in the same manner as in Example 1 except that the azo metal compound (Formula 2) was replaced by 1 part of the azo metal compound (Formula 8). The volume resistance of this toner is 8 ×
10 ¹⁰ Ωcm, the content ratio of the azo metal compound to the triphenylmethane compound is 83:17 by weight, and the total content of the azo metal compound and the triphenylmethane compound is in the toner. 1.26% by weight.

Example 4 A toner of the present invention was obtained in the same manner as in Example 1 except that the azo metal compound (Chemical Formula 2) was replaced by 2 parts of the azo metal compound (Chemical Formula 9). The volume resistance of this toner is 7 ×
10 ¹⁰ Ωcm, the content ratio of the azo metal compound to the triphenylmethane compound is 91: 9 by weight, and the total content of the azo metal compound and the triphenylmethane compound is in the toner. 2.1% by weight.

Example 5 91.8 parts of styrene-acrylic acid ester copolymer (trade name: CPR-100, manufactured by Mitsui Chemicals) 7 parts of carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Corporation) Azo-based metal compound 8) 0.1 part Triphenylmethane compound (Chemical formula 12) 2 parts Low molecular weight polypropylene 2 parts (Viscol 330P manufactured by Sanyo Chemical Industry Co., Ltd.)

The above-mentioned raw materials were mixed by a super mixer, kneaded by hot-melt in a twin-screw kneader, pulverized by a jet mill, and then classified by a dry air classifier to have a volume average particle diameter of 8 μm.
20% of all particles have a number particle size of 5 μm or less
In addition, particles having a volume particle diameter of 16 μm or more in all particles obtained particles having a particle diameter distribution of 2%. Next, the particles 9
8.4% by weight, 0.6% by weight of hydrophobic silica (trade name: HVK-2150, manufactured by Clariant Japan) and 1.0 of magnetite (trade name: MAT-222, manufactured by Kanto Denka)
% By weight in a Henschel mixer for 5 minutes to obtain the toner of the present invention. The volume resistance of this toner is 9 ×
10 ¹⁰ Ωcm, the content ratio of the azo metal compound to the triphenylmethane compound is 5:95 by weight, and the total content of the azo metal compound and the triphenylmethane compound is in the toner. 2.2% by weight.

Comparative Example 1 A comparative toner was obtained in the same manner as in Example 1 except that only the triphenylmethane compound (Chemical Formula 12) was omitted. In addition,
The volume resistance of this toner was 7 × 10 ¹⁰ Ωcm.

Comparative Example 2 A comparative toner was obtained in the same manner as in Example 2 except that only the triphenylmethane compound (Chemical Formula 12) was omitted. In addition,
The volume resistance of this toner was 12 × 10 ¹⁰ Ωcm.

Comparative Example 3 A comparative toner was obtained in the same manner as in Example 3 except that only the triphenylmethane compound (Chemical Formula 12) was omitted. In addition,
The volume resistance of this toner was 8 × 10 ¹⁰ Ωcm.

Comparative Example 4 A comparative toner was obtained in the same manner as in Example 5 except that only the azo metal compound (Formula 8) was omitted. The volume resistance of this toner was 8 × 10 ¹⁰ Ωcm.

Comparative Example 5 A comparative toner was obtained in the same manner as in Example 1 except that the blending amount of carbon black was changed to 15 parts. The volume resistance of this toner was 2 × 10 ¹⁰ Ωcm.

Comparative Example 6 A comparative toner was obtained in the same manner as in Example 1 except that the amount of carbon black was changed to 2.5 parts. The volume resistance of this toner was 17 × 10 ¹⁰ Ωcm.

Comparative Example 7 In place of the triphenylmethane compound (Chemical Formula 12),
Grade ammonium salt (trade name P-5, manufactured by Orient Chemical Co., Ltd.)
1) A comparative toner was obtained in the same manner as in Example 1 except that the amount was changed to 0.2 part. The volume resistance of this toner is 8 × 1
It was 0 ¹⁰ Ωcm. Next, 4 parts by weight of each of the toners of Examples 1 to 5 and Comparative Examples 1 to 7 and 100 parts by weight of the silicone-coated ferrite carrier were mixed to obtain a two-component developer.

The two-component developers of Example 5 and Comparative Example 4 were commercially available copying machines (trade name SD-2 manufactured by Sharp Corporation).
060), and the other two-component developer is applied to a commercial copying machine (product name: SF-9800, manufactured by Sharp Corporation) to continuously copy up to 10,000 sheets of A4 paper with a 6% black area. The following items were tested. Table 1 shows the results.

Friction Charge The charge of the toner was measured using a blow-off powder charge measuring device manufactured by Toshiba Chemical Corporation. Image density Reflectance densitometer RD-914 manufactured by Macbeth (practical range 1.
35 or more). Background fog in non-image area Measured using a colorimetric colorimeter ZE-2000 (practical range 1.00 or less) manufactured by Nippon Denshoku Co., Ltd. Toner scattering state After copying 10,000 sheets, the area around the developing machine was visually checked.
Those generated in a large amount were judged as x.

[0059]

[Table 1]

According to Table 1, in Examples 1 to 5 which satisfy the conditions of the present invention, the amount of triboelectric charge is stable even after 10,000 copies are made, and there is no significant change in image density or background fog. It was confirmed that toner scattering did not cause any problem in practical use. On the other hand, in Comparative Examples 1, 2, 3, 4, and 6, the image density after 10,000 sheets was low, and there was a practical problem. In Comparative Examples 5 and 7, it was confirmed that there was a lot of background fog and there was a problem in practical use.

[0061]

As described above, according to the electrophotographic toner of the present invention, it can be applied to both copying machines and the like using positively and negatively chargeable photoconductors. Since stable triboelectric charging properties can be obtained over a long period of time in both positive charging properties, sufficient image density and stable image characteristics with less background fog can be obtained.

Claims (4)

[Claims] 1. A binder resin, a coloring agent, an azo metal compound and a triphenylmethane compound as main components, and the content ratio of the azo metal compound to the triphenylmethane compound is 3:97 to 97 by weight. : 3 and volume resistance is 3 × 1
A toner for electrophotography, wherein the toner has a particle size of 0 ¹⁰ to 15 × 10 ¹⁰ Ωcm. 2. The toner according to claim 1, wherein the total content of the azo metal compound and the triphenylmethane compound is 0.5 to 3% by weight in the toner.
The electrophotographic toner according to claim 1, wherein: 3. A volume average particle diameter of 6 to 9 μm,
The electrophotographic toner according to claim 1, wherein the particles having a number particle diameter of 5 µm or less have a particle diameter distribution of 15 to 50% and those having a volume particle diameter of 16 µm or more have a particle diameter distribution of 0 to 3%. 4. The electrophotographic toner according to claim 1, wherein 0.5 to 2% by weight of hydrophobic silica and 0.5 to 2% by weight of magnetite are adhered to the surface.