JPH0324560A - Electrophotographic dry toner - Google Patents

Abstract

PURPOSE:To obtain a toner adapted to a magnetic brush cleaning process, to be freed of fogging and the like and capable or forming a sharp image by using a composition of a binder resin, carbon black, and a copper-phthalocyanine type pigment each in a specified proportion. CONSTITUTION:The toner comprises 100 pts.wt. of the binder resin, 2.0 - 8.0 pts.wt. of the carbon black, and 0.1 -3.0 pts.wt. of the copper-phthalocyanine type pigment. The toner not transferred and remaining on an electrostatic charge image bearing body can be sufficiently removed by the magnetic brush cleaning process without causing any toner attaching phenomenon even when electric field intensity is elevated in order to execute perfect cleaning, thus permitting highly sharp images freed of fogging and the like to be stably obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic dry toner, particularly an electrophotographic dry toner that is compatible with a magnetic brush cleaning method and stably forms clear images without fogging. Regarding.

[Prior Art] As shown in FIG. 1, an electrophotographic copying apparatus generally includes an image carrier 1 (not limited to a drum shape but may also be a belt shape) and a charger 2, Optical system 3,
It consists of a developing section 4, a transfer charger 5, a separation charger 6, and a cleaning section 7.

The transfer charger 5 is used to transfer the toner image on the photoreceptor 1 to a transfer paper 8 such as plain paper, and the separation charger 6
is used to separate the transfer paper 8 bearing the toner image from the surface of the photoreceptor 1. In the drawings, numeral 9 indicates a separation claw.

By the way, either a dry development method or a wet development method (including a semi-dry development method) is used to visualize an electrostatic charge image, but the former is more effective in obtaining a dry reproduction. Because of this, the dry developing method is the mainstream for Genka.

Dry development method uses a one-component developer (consisting only of toner)
It is broadly classified into two-component developers (consisting of carrier and toner). In any case, it is ideal that all the toner images made visible by such a developer be transferred to the transfer paper, but at the end of the process, the toner that could not be completely transferred remains on the photoreceptor. This residual toner must be removed by a cleaning device.

Methods for cleaning residual toner (untransferred toner) are (1) fur brush, (2) blade, (3)
It is generally done using a magnetic brush or the like. However,
The fur brush method requires a large cleaning device, and
Some dislikes include the fact that it tends to cause filming on the photoreceptor. Further, the blade method has drawbacks such as the fact that the photoreceptor is easily damaged. On the other hand, cleaning using a wide magnetic brush eliminates the disadvantages of (1) and (2) above, but has the disadvantage that sufficient cleaning performance cannot be obtained when there is a large amount of residual toner, such as untransferred toner. Therefore, in order to improve cleaning performance, it is being considered to apply a bias voltage to attract toner to the cleaning sleeve, or to apply a charge with the same polarity as the toner to the surface of the image carrier before cleaning to improve cleaning performance. .

Further, in JP-A No. 132-276082, the cleaning performance is improved by lowering the carrier resistance in the cleaning agent. All of these methods improve the cleaning performance by using an electric field that attracts toner from the image carrier to the cleaning sleeve, and the cleaning performance is certainly improved. However, if the electric field in this cleaning area is increased until the untransferred toner is completely cleaned, a phenomenon occurs in which the toner adheres to the non-image area of the image carrier, making it virtually impossible to clean the untransferred toner. It was impossible.

Furthermore, in JP-A-58-102273, the carrier used in the cleaning device uses a carrier with stronger triboelectric charging properties than the carrier used in the developing device, but in order to increase the charging property, a coating layer such as a resin is provided to improve the cleaning carrier. has a high resistance and does not have the cleaning performance to completely remove untransferred toner.

Problems to be Solved by the Invention Under these circumstances, the present invention provides a dry toner for electrophotography that is well suited for magnetic brush cleaning, is free from fogging, and is capable of forming clear images. The purpose is to provide

[Means for Solving Problems] The present invention provides a toner containing a binder resin, carbon black, and a copper phthalocyanine pigment, in which 2 parts by weight of carbon black is added to 100 parts by weight of the binder resin.
．． 0 to 8.0 parts by weight, 0.1 parts by weight of copper phthalocyanine pigment
This is a dry toner for electrophotography, characterized in that it contains 3,0 to 3,0 times a day.

Normally, about 90% of the developed toner image is transferred to the recording medium, and the cleaning device transfers about 10% of the developed toner image to the recording medium.
The toner image is removed, but in some cases, the untransferred toner image is also cleaned.

This may occur if the recording medium such as transfer paper has wrinkles and the transfer is poor, if the area of the recording medium is smaller than the development area, or if there is a jam (paper jam) before the transfer.

In the magnetic brush cleaning method, when the amount of toner to be removed is large, such as an untransferred image, there is a marked tendency for cleaning performance to deteriorate.

In order to improve this, a magnetic brush cleaning method has been studied in which an electric field is generated in a direction that attracts toner from the image carrier to the cleaning sleeve to improve the cleaning performance.

Specifically, there is a method of applying a bias voltage to the cleaning sleeve or applying an electric current Gj of the same polarity as the toner to the surface of the image carrier.

However, if the electric field is increased to the extent that untransferred toner can be removed using this method, a phenomenon occurs in which toner adheres to non-image areas.

The inventors of the present invention have conducted intensive studies to eliminate this toner adhesion phenomenon without impairing cleaning performance, and have found that the objective can be achieved by selecting the dielectric constant, carbon content, and additives of the toner. This led to the present invention.

As a result of further study on the dielectric constant of toner, it was found that toner dielectric skewers vary in degree depending on the type of binder resin, but dielectric skewers vary greatly depending on the amount of carbon blended to give blackness to toner.

As the amount of carbon decreases, the dielectric constant of toner decreases significantly, and within the range of resins conventionally used as binder resins for toner, it is possible to reduce the dielectric constant to 3.5 or less by reducing the amount of carbon. It has been found.

However, if the amount of carbon is simply reduced, the blackness of the toner becomes insufficient, resulting in a poor color tone with a slight reddish tinge. Also,
When the amount of carbon is reduced, the saturation value of toner charge due to mixing and stirring of toner and carrier increases, but the charge increase rate (hereinafter abbreviated as charge rise property) decreases, resulting in so-called "gabbery" that stains the background part of the image during development. A problem also occurred in that it became more likely to occur.

As a result of investigating materials that can maintain blackness even when the amount of carbon is reduced and improve charge rise properties, we found that copper phthalocyanine pigments have both of the above two effects, and also improve cleaning properties and toner adhesion properties. It was found that the degree of margin increases.

The copper phthalocyanine pigment is a blue pigment having the structure shown in Structural Formula-1, and has shown particularly good results in positive polarity toners.

As more and more chlorine is added to the benzene nuclei, the chargeability becomes negative, and when 12 or more chlorine atoms are added, the benzene nucleus takes on a green color.

This chlorine-introduced copper phthalocyanine pigment showed particularly good results in negative polarity toners. 16 chlorine in structural formula-2
It shows the horizontal construction of the individual introduced.

Structural Formula-1 Structural Formula-2 The preferred content of these carbon black and copper phthalocyanine pigments is 2.0 to 8.0 parts by weight of carbon plaque per 100 parts by weight of the binder resin. Q Ift amount is 0.1 to 3.0 parts by weight of the copper phthalocyanine pigment.

The toner dielectric constant defined in the present invention is TR-
This is the value determined by Apl at a frequency of IKHz using a 10'42 dielectric loss AH regulator.

The sample is 3g of toner using a fluorescent X-ray sample die SD.
-40 (manufactured by Rigaku Denki) and applied a pressure of 6 tons for 1 minute using an electric press machine. A pellet of lmφ was prepared. As the binder resin used in the present invention, as described above, all binder resins that can be conventionally used as binder resins for toners can be used.

For example, boristyrene, chloroboristyrene, poly~α
-Methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene- Acrylic ester copolymers (styrene-methyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer,
Styrene-phenyl acrylate copolymer, etc.), styrene-methacrylate ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-methacrylate copolymer) acid phenyl copolymer), styrene-α
- Styrenic resins such as methyl chloroacrylate copolymer, styrene-acrylonitrile-acrylic ester copolymer (Ill polymer or copolymer containing styrene or styrene substitutes), vinyl chloride resin, styrene-vinyl acetate copolymer Coalescence, rosin-modified maleic acid resin, phenolic resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral There are resins, etc., but these resins are not suitable for use alone with tl1, but two or more types can also be used in combination.

The carbon black used in the present invention can be any of those conventionally used for coloring toners, such as channel black, furnace black, acetylene black, lamp black, etc. However, if the particles are small, the degree of blackness increases, but the dielectric constant is high. Therefore, it is necessary to reduce the blending amount.

In addition, known highly polar substances such as nigrosine dyes, quaternary ammonium salts, monoazo dyes, salicylic acid metal salts, etc. can be used as charge control agents to adjust the polarity and resistance of the toner. The cleaning carrier is made of magnetic powder such as iron, ferrite, magnetite, etc., and it does not matter whether it is coated or not, but a low resistance is advantageous for cleaning performance.

An example of a magnetic brush cleaning device is shown in FIG. 1, and has a structure in which at least a cleaning carrier is magnetically attracted to the surface of a cylindrical sleeve 71 containing a magnet.

Furthermore, a bias voltage is applied to the cleaning sleeve or image carrier to electrostatically attract the toner toward the cleaning sleeve, or a charger (see step 10 in the first step) or the like is placed on the surface of the image carrier before cleaning to absorb the toner. This device is capable of applying an electrostatic force in the direction of the cleaning sleeve to the toner in the area where the cleaning carrier ear and the image bearing member come into contact with each other by applying a polar charge.

The cleaned toner is electrostatically attracted and collected by a collection roller 74, scraped off by a collection blade 76, and discharged outside the prefecture by a discharge screw.

[Example] Next, examples will be shown. Parts here are by weight.

Examples 1 to 2 and Comparative Examples 1 to 6 The following formulations were kneaded in a two-roll mill, cooled, coarsely pulverized (rotobrex), finely pulverized in a jet mill, and classified in a wind separator. A positive polarity toner having a volume average particle diameter of 1 μm was obtained.

Styrene-n-butyl methacrylate copolymer (possible
-120,000. ″My -9.000.Tg
-58℃) t00 parts Carbon black (Mitsubishi Kasei #44) Table 1 amount Copper phthalocyanine pigment (Toyo Ink Co., Ltd. On01Blue P
G-7351) Amounts shown in Table 1 Nigrosine dye (Orient Chemical Nigrosine Base IEX)
0.5 parts Table 1 if(7)l: Amorphous iron oxide powder (TEFv200/30
0) An OPC photoreceptor was used as the image carrier (1).

Cleaning sleeve (7l) two too v and one three
00V was applied and the photoconductor surface was charged with a pre-cleaning charger so that the potential iIj was +150V, and the cleaning performance and the copied image were evaluated. Table 2 shows the results.
Shown below.

Note that 01Δ and × in the table represent good, slightly poor, and poor, respectively.

The cleaning performance was evaluated on untransferred images.

Table 2 3.0 parts of the toner obtained above and 97.0 parts of amorphous iron oxide powder (TEPV 200/300 manufactured by Nippon Iron Powder)
The mixture was placed in a mold blender and mixed and stirred for 5 minutes to prepare a developer.

The above developer was put into the developing section (4) of the electrophotographic copying machine shown in FIG. 1, and the following formulation was applied under the same conditions as in Example 1. A toner was obtained to obtain a negative polarity toner.

Polyester resin made by condensation polymerization of polyoxyethylated bisphenol A, terephthalic acid, and trimellitic acid (100,000 units, 3,000 units of Ishishita, oxidized te.o.
, Tg 58°C) 100 parts carbon plaque (Mitsubishi Kasei #44) Amount shown in Table 3 Chlorine-introduced copper phthalocyanine pigment (Toyo Ink Lionol G
raan YS Cl-18) Table 3 Amounts of metal complex dye (manufactured by Hodogaya Chemical) 1.0 part Table 3 Next, 0.5 part of the above toner and amorphous iron oxide powder (TEFV)
A cleaning agent was prepared by mixing and stirring 99.5 parts of a carrier (200/300) coated with silicone resin to a thickness of 0.4 μm using a V-type blender for 15 minutes. A developer and a cleaning agent were put into the developing section and magnetic brush cleaning device of the electrophotographic copying apparatus shown in FIG. 1, and an Se photoreceptor was used as the image carrier.

Table 4 shows the results of evaluating cleaning properties and copied images by applying +300 V and +too much voltage to the cleaning sleeve, and charging the photoreceptor surface with a pre-cleaning charger so that the surface potential was -150 V.

Note that 01Δ and X in the table represent good, slightly poor, and poor, respectively.

A developer was prepared by mixing and stirring 3.0 parts of the above-obtained toner and 97.0 parts of a carrier obtained by coating silicone resin on ferrite powder (average particle size 90 μm) to a thickness of 1 μm using a V-type blender for 15 minutes.

Table 4 [Effects of the Invention] As explained above, the dry toner for electrophotography according to the structure of the present invention has a magnetic brush cleaning method in which the electric field strength is increased to completely clean even the untransferred toner on the image tLl body. Even if the temperature is increased, toner adhesion does not occur, and the toner has sufficient cleaning properties.In addition, this toner provides sufficient image blackness and has good charge rise properties, so it does not cause any force fluctuation. This makes it possible to stably obtain images with excellent sharpness and no blemishes.

The toner contains 2.0 to 8.0 parts by weight of carbon plaque and 0.0 to 8.0 parts by weight of copper phthalocyanine pigment based on 100 parts by weight of binder resin. By containing 1 to 3.0 parts by weight, the dielectric constant of the toner becomes 3.5 or less, and a magnetic brush cleaning method showing even better cleaning performance can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a magnetic brush cleaning device and an electrophotographic copying device. 1... Image carrier 2... Charger 3.
...Optical system 4...Developing section 5...Transfer charger 6...Separation charger 7...Cleaning section 8...Transfer paper 9...Separation claw lO...Pre-cleaning charger 4L...・Developing sleeve 411...Magnet 42...
・Sensor 43... Paddle wheel 7l...
・Cleaning sleeve 72, 73...Pumping roller 74...Collection roller 75...Cleaning scraper

Claims (1)

[Claims] In a toner containing a binder resin, carbon black, and a copper phthalocyanine pigment, 2.0 to 8.0 parts of carbon black is added to 100 parts by weight of the binder resin.
A dry toner for electrophotography, characterized in that it contains 0.1 to 3.0 parts by weight of a copper phthalocyanine pigment.