JP3519652B2 - Magnetic one-component developer and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic one-component developer used in electrophotography and a method for producing the same , and more specifically, high image density and transfer efficiency, and occurrence of memory phenomenon. TECHNICAL FIELD The present invention relates to a magnetic one-component developer for jumping development, which prevents or reduces the above-mentioned phenomenon, and a manufacturing method thereof .

[0002]

2. Description of the Related Art Generally, electrophotography is a method in which a latent image is electrically formed on a photoconductor, the latent image is developed with a toner, and the toner image is transferred to a transfer material such as paper as required. After that, the toner image is fixed on the transfer material by means such as heating and pressing to obtain a copy. Developers used in such an electrophotographic method include a two-component developer including a toner component and a carrier component, and a one-component developer having both the functions of the toner and the carrier.

The two-component developer is excellent in electrophotographic characteristics such as transferability, fixability and environmental resistance. However, since it is necessary to control the mixing ratio of the toner component and the carrier component, a toner concentration sensor is required for the developing device, and a stirring mechanism for stirring the toner component and the carrier component is required. It had problems such as becoming complicated and complicated. Further, the two-component developer is prone to deterioration and has a problem that the life is short.

In recent years, a developing method using a magnetic one-component developer has been proposed and put into practical use in order to make the developing device compact and simple and to achieve both electrophotographic characteristics. To develop a magnetic one-component developer, the magnetic one-component developer is carried by contacting the magnetic one-component developer carried on a non-magnetic sleeve with a photoreceptor carrying an electrostatic latent image. A contact type magnetic one-component developing method in which the image is transferred to the image for development and a non-magnetic sleeve carrying the magnetic one-component developer and the photoconductor holding the electrostatic latent image have a constant gap (gap). ) Is provided, and the magnetic one-component developer is transferred (jumping) to the electrostatic latent image in a non-contact manner to develop the non-contact type magnetic one-component developing method.

FIG. 1 is a schematic view of an apparatus used in a non-contact type magnetic one-component developing method. This developing device includes a cylindrical photosensitive drum 1 which is an electrostatic latent image holder, a hopper 2 in which a magnetic one-component developer 3 is stored, and a photosensitive drum 1.
And a non-magnetic sleeve 6 made of aluminum whose right half peripheral surface is housed in the hopper 2 and whose left half peripheral surface faces the photoconductor drum 1, and a non-magnetic sleeve 6 incorporated therein. The magnetized roller 5 and the magnetic blade 4 which makes the layer of the magnetic one-component developer 3 carried on the non-magnetic sleeve 6 uniform in thickness and the magnetic one-component developer 3 in the hopper 2 are agitated. The stirrer 7, the non-magnetic sleeve 6 and the magnetic blade 4 are kept in an electrically conductive state,
The photoconductor drum 1 has a power supply 8 for applying an alternating bias voltage and a DC bias voltage.

A non-contact type magnetic one-component developing method using this apparatus is carried out as follows. First, an electrostatic latent image is formed on the surface of the photosensitive drum 1 by a known electrophotographic method. On the other hand, the magnetic one-component developer 3 in the hopper 2 is
The magnetic blade 4 is carried on the surface of the non-magnetic sleeve 6 containing the magnet roller 5 so as to have a constant layer thickness, and is conveyed. By indicia pressurizing the alternating bias voltage and a DC bias voltage to the photosensitive drum 1 from the power supply 8 produces alternating electric field and a DC electric field between the nonmagnetic sleeve 6 and the photosensitive drum 1, the nonmagnetic sleeve 6 surface The magnetic one-component developer 3 is jumped and developed into an electrostatic latent image on the surface of the photosensitive drum 1.

As described above, in the developing method using the magnetic one-component developer, the device is simplified and the device can be downsized. However, since the magnetic one-component developer contains a large amount of magnetic material, it is difficult to obtain a uniform charge and the transfer efficiency onto a transfer material such as paper is poor.

In order to improve the transfer efficiency of the magnetic one-component developer, it has been proposed to use a magnetic toner containing silicone oil as the magnetic one-component developer. However, in such a magnetic toner containing silicone oil, although the transfer efficiency is improved, the fluidity of the magnetic toner is lowered, so that an appropriate toner film thickness cannot be maintained, and the image density becomes low. There is a problem that the image density is low, and the image density is remarkably reduced particularly when printing a large number of sheets.

When the magnetic toner contains silicone oil, due to the high charging property of the silicone oil, when the non-magnetic sleeve is rotated and rotated twice or more to develop, the first toner is developed. A phenomenon in which the magnetic one-component developer remaining on the surface of the non-magnetic body sleeve without being completely transferred to the photosensitive drum appears as an afterimage at the time of the second development, that is, a memory phenomenon occurs, particularly when printing a large number of sheets. There was a problem that the memory phenomenon became remarkable.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic one-component developer having excellent transfer efficiency, high image density and less memory phenomenon, and a method for producing the same.

[0011]

That is, the magnetic one-component developer of the present invention has a base magnetic toner containing a binder resin, a magnetic material and silicone oil, and the base magnetic toner.
By adding silicone oil to the surface of the maternal magnetic toner
After attaching silicone oil to the, add fine silica powder.
It is characterized by adding . The content of silicone oil in the base magnetic toner is preferably 0.1 to 0.5% by weight. Further, the amount of silicone oil attached to the surface of the base magnetic toner is preferably 0.01 to 0.1 parts by weight with respect to 100 parts by weight of the base magnetic toner. Also, the magnetic one-component development of the present invention
The manufacturing method of the agent is a binder resin, a magnetic substance and a silicone oil.
Silicone oil added to base magnetic toner containing
Then, attach silicone oil to the surface of the base magnetic toner.
After that, silica fine powder is added.

[0012]

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
Magnetic one-component developer of the present invention, containing a silicone oil
It has a maternal magnetic toner, silicon to the base magnetic toner
It is characterized in that the silica oil is added to the surface of the silicone oil and then the silica fine powder is added thereto. The base magnetic toner contains at least a binder resin, a magnetic material, and silicone oil, and may contain a colorant, a charge control agent (charge control agent), a wax, etc., if necessary.

Examples of the binder resin include polystyrene, poly-p-chlorostyrene, polyvinyltoluene,
Styrenes such as styrene-p-chlorostyrene copolymers and styrene-vinyltoluene copolymers, homopolymers of styrene and its substitution products and copolymers thereof; styrene-methyl acrylate copolymers, styrene-ethyl acrylate copolymers Copolymers of styrene and acrylates such as polymer, styrene-n-butyl acrylate copolymer; styrene-
Copolymers of styrene and methacrylic acid ester such as methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylic acid-n-butyl copolymer; styrene and acrylic acid ester and methacrylic acid ester Other styrene copolymers; styrene-acrylonitrile copolymer, styrene vinyl methyl ether copolymer, styrene butadiene copolymer, styrene vinyl methyl ketone copolymer, styrene acrylonitrile indene copolymer, styrene-maleic acid ester Styrene-based copolymers of styrene and other vinyl-based monomers such as copolymers; polymethyl methacrylate, polybutyl methacrylate, polyester resins, polyvinyl acetate polyester, polyamide resins, epoxy resins, polyvinyl butyral, polyac Le acid phenol resins, aliphatic or alicyclic hydrocarbon resins, petroleum resins, chlorinated paraffin, and the like. These can be used alone or as a mixture.

As the magnetic material, for example, cobalt, iron,
Metals such as nickel, aluminum, cobalt, copper, iron,
Used for nickel, magnesium, tin, zinc, gold, silver, selenium, titanium, tungsten, zirconium, alloys of other metals, metal oxides such as aluminum oxide, iron oxide, nickel oxide, ferromagnetic ferrite, magnetite or mixtures thereof. To be The average particle size of the magnetic substance is not particularly limited, but is preferably 0.05 to 3 μm. Also, the content of the magnetic material is not particularly limited,
It is preferably 65% by weight or less with respect to the magnetic toner.

Examples of the silicone oil include dimethyl polysiloxane and phenyl group-containing polysiloxane. In addition, methyl styrene or olefin modified silicone oil, polyether modified silicone oil, alcohol modified silicone oil, fluorine modified silicone oil, hydrophilic special modified silicone oil, amino modified silicone oil, mercapto modified silicone oil, epoxy modified Silicone oil, carboxyl modified silicone oil , higher fatty acid modified silicone oil, carnauba modified silicone oil,
Modified silicone oil <br/> and amide-modified silicone oil may be used. The silicone oil contained in the mother magnetic toner and the silicone oil attached to the surface of the mother magnetic toner may be the same or different.

Such a silicone oil is preferably contained in the base magnetic toner in an amount of 0.1 to 0.5% by weight. When the content of silicone oil is less than 0.1% by weight, the transfer efficiency tends to deteriorate. When the content of silicone oil exceeds 0.5% by weight, the image density is lowered when printing a large number of sheets, and black solid memory is likely to occur. The amount of silicone oil attached to the surface of the base magnetic toner is preferably 0.01 to 0.1 parts by weight based on 100 parts by weight of the base magnetic toner. The amount of silicone oil adhered to the base magnetic toner 10
If it is less than 0.01 parts by weight with respect to 0 parts by weight, the transfer efficiency tends to deteriorate. If the amount of silicone oil adhered exceeds 0.1 parts by weight with respect to 100 parts by weight of the base magnetic toner, the image density will decrease when printing a large number of sheets, and black solid memory will likely occur.

As the colorant, for example, the following pigments or dyes can be used. Carbon black, aniline blue (CINo.50405), calco oil blue (CI
No.azoec Blue 3), Chrome Yellow (CINo.1409
0), Ultramarine Blue (CINo.77103), DuPont Oil Red (CINo.26105), Orient Oil Red # 330 (CINo.47005), Methylene Blue Chloride (CINo.52015), Phthalocyanine Blue (CINo.7).
4160), malachite green oxalate (CINo.420
00), Lamp Black (CINo.77266), Rose Bengal (CINo.45435) and mixtures thereof.

As the charge control agent, for the (+) toner,
Nigrosine-based electron-donating dyes, metal salts of naphthenic acid and higher fatty acids, alkoxylated amines, quaternary ammonium salts, alkyd amides, phosphorus, tungsten, molybdic acid lake pigments, fluorine treatment activators and the like are used.
For the (−) toner, an electron-accepting organic complex, chlorinated paraffin, chlorinated polyester, polyester having excess acid groups, sulfonylamine of copper phthalocyanine and the like are used.

The wax is for improving the releasability of the base magnetic toner at the time of heat roll fixing. As such a wax, well-known waxes such as low molecular weight polyethylene, low molecular weight polypropylene, carnauba wax, and paraffin wax can be used.

The volume average particle diameter of the base magnetic toner is not particularly limited, but is preferably 5 to 20 μm. The surface of the maternal magnetic toner, charge stability, developability, fluidity, for improving the durability and the like, are surface-treated with silica fine powder. Further, the silica fine powder may be hydrophobized with an organic silicon compound such as a silicone varnish, a silicone oil, or a silane coupling agent for the purpose of hydrophobizing and controlling the charging property.

The magnetic one-component developer of the present invention is manufactured, for example, as follows. First, the binder resin, magnetic material,
Silicone oil, and further, if necessary, a colorant, a charge control agent (charge control agent), a wax, etc. are charged into a mixer such as a super mixer or a Henschel mixer, and sufficiently mixed, and then a biaxial kneader, The mixture is melted and kneaded by a kneader such as a heating roll or a kneader. Next, the kneaded product is crushed by a crusher such as a jet mill and classified by a classifier to obtain a base magnetic toner. The maternal magnetic toner by adding a silicone oil, and stirred by a Henschel mixer or the like, further added by silica fine powder to obtain a magnetic one-component developer of the present invention with stirring.

Next, the developing method of the present invention using the above magnetic one-component developer will be described in detail. FIG. 1 is a schematic view of a developing device used in the method for developing a magnetic one-component developer of the present invention. This developing device is installed with a cylindrical photosensitive drum 1 serving as an electrostatic latent image holder, a hopper 2 containing a magnetic one-component developer 3, and a constant gap with respect to the photosensitive drum 1. The right half-circumferential surface is housed in the hopper 2, and the left half-circumferential surface faces the photoconductor drum 1, a non-magnetic sleeve 6 made of aluminum, a magnet roller 5 contained in the non-magnetic sleeve 6, and a non-magnetic sleeve. 6, a magnetic blade 4 for equalizing the thickness of the layer made of the magnetic one-component developer 3 carried on the magnetic disk 6, an agitator 7 for agitating the magnetic one-component developer 3 in the hopper 2, a non-magnetic sleeve 6 and a magnetic material. The body blade 4 is kept electrically connected to the photosensitive drum 1
And a power supply 8 for applying an alternating bias voltage and a DC bias voltage. The gap between the non-magnetic sleeve 6 and the photosensitive drum 1 is about 50 to 400 μm.

The developing method of the magnetic one-component developer of the present invention using this developing apparatus is carried out as follows. First,
An electrostatic latent image is formed on the surface of the photosensitive drum 1 by a known electrophotographic method. On the other hand, the magnetic one-component developer 3 in the hopper 2 is transferred to the magnet roller 5 by the magnetic blade 4.
Is carried on the surface of the non-magnetic sleeve 6 enclosing it so as to have a constant layer thickness, and conveyed. Here, by <br/> indicia pressurizing the alternating bias voltage and a DC bias voltage to the photosensitive drum 1 from the power source 8, an AC electric field and a DC electric field between the nonmagnetic sleeve 6 and the photosensitive drum 1 occurs The magnetic one-component developer 3 on the surface of the non-magnetic sleeve 6 is jumped and developed into an electrostatic latent image on the surface of the photosensitive drum 1.

[0025]

The present invention will be described in more detail based on the following examples. [Example 1] (Preparation of base magnetic toner) Styrene-acrylic ester copolymer resin (binder resin, CPR-1 manufactured by Mitsui Chemicals, Inc.)
00) 56.7 parts by weight, magnetite particles (magnetic material, Toda Kogyo's EPT-1000) 38 parts by weight, silicone oil (Shin-Etsu Silicone KF-69) 0.3 parts by weight, metal-containing dye (charge control agent). , ORIENT CHEMICAL INDUSTRIES, LTD. BONTRON S-34) 2 parts by weight, and low molecular weight polypropylene wax (Sanyo Kasei Co., Ltd. VISCOL 330P) 3 parts by weight are mixed with a super mixer, and after hot melt kneading with a biaxial kneader, It is crushed with a jet mill and then classified with a dry classifier to obtain a volume average particle size of 9μ.
m base magnetic toner was obtained.

(Preparation of Magnetic One-Component Developer) To 100 parts by weight of the above-mentioned base magnetic toner, 0.05 part by weight of silicone oil (KF-69 manufactured by Shin-Etsu Silicone Co., Ltd.) was added, and the mixture was stirred with a Henschel mixer to obtain the base magnetism. Silicone oil was adhered to the toner surface. Next, hydrophobic silica (TS-530, manufactured by Cabot Corporation) was added to the base magnetic toner so that the hydrophobic silica was 1 part by weight with respect to 100 parts by weight of the base magnetic toner, and the mixture was stirred again with a Henschel mixer. A magnetic one-component developer of the present invention was obtained.

[Example 2] A magnetic one-component developer of the present invention was obtained in the same manner as in Example 1 except that 0.03 part by weight of silicone oil added to adhere to the surface of the base magnetic toner was used. It was [Example 3] A magnetic one-component developer of the present invention was obtained in the same manner as in Example 1 except that the amount of silicone oil added to adhere to the surface of the base magnetic toner was 0.07 part by weight.

[Example 4] Silicone oil added to the base magnetic toner was 0.2 part by weight, and the binder resin was 5 parts.
A magnetic one-component developer of the present invention was obtained in the same manner as in Example 1 except that the amount was 6.8 parts by weight. Example 5 A magnetic single component of the present invention was prepared in the same manner as in Example 1 except that the silicone oil added to the base magnetic toner was 0.4 parts by weight and the binder resin was 56.6 parts by weight. A developer is obtained.

Example 6 Silicone oil added to the base magnetic toner was 0.2 parts by weight, and the binder resin was 5 parts.
A magnetic one-component developer of the present invention was obtained in the same manner as in Example 1 except that the amount was 6.8 parts by weight and the amount of silicone oil added for adhering to the surface of the base magnetic toner was 0.03 parts by weight. . [Example 7] The silicone oil added to the base magnetic toner was 0.4 parts by weight, the binder resin was 56.6 parts by weight, and the silicone oil added to adhere to the surface of the base magnetic toner was 0. A magnetic one-component developer of the present invention was obtained in the same manner as in Example 1 except that the amount was 0.07 part by weight.

Comparative Example 1 (Preparation of Base Magnetic Toner) A base magnetic toner was obtained in the same manner as in Example 1 except that silicone oil was not added. (Preparation of Magnetic One-Component Developer) A surface treatment with silica was carried out in the same manner as in Example 1 without attaching silicone oil to the surface of the base magnetic toner to obtain a magnetic one-component developer.

[Comparative Example 2] Silicone oil added to the base magnetic toner was 0.4 parts by weight, and the binder resin was 5 parts.
A magnetic one-component developer was obtained in the same manner as in Comparative Example 1 except that the amount was 6.6 parts by weight. [Comparative Example 3] A magnetic one-component developer was prepared in the same manner as in Comparative Example 1 except that the silicone oil added to the base magnetic toner was 0.5 parts by weight and the binder resin was 56.5 parts by weight. Obtained.

[Comparative Example 4] Silicone oil added to the base magnetic toner was 0.6 parts by weight, and the binder resin was 5 parts.
A magnetic one-component developer was obtained in the same manner as in Comparative Example 1 except that the amount was 6.4 parts by weight. [Comparative Example 5] A magnetic one-component developer was obtained in the same manner as in Example 1 except that silicone oil was not added to the base magnetic toner.

[Comparative Example 6] The same procedure as in Example 1 was carried out except that silicone oil was not added to the base magnetic toner, and the amount of silicone oil added for adhering to the surface of the base magnetic toner was 0.075 parts by weight. Thus, a magnetic one-component developer was obtained. [Comparative Example 7] Magnetic property was the same as in Example 1 except that silicone oil was not added to the base magnetic toner and the amount of silicone oil added to adhere to the surface of the base magnetic toner was 0.09 parts by weight. A one-component developer was obtained.

[Evaluation Method] The following tests were carried out on the magnetic one-component developers of the above Examples and Comparative Examples. An original having the pattern shown in FIG. 2 was printed four times with a Casio printer, 4150II M / C, using the magnetic one-component developers of the above-mentioned Examples and Comparative Examples, and then a black solid image was printed. did. And, regarding the black solid image,
The image density and black solid memory were evaluated. The test results are shown in Table 1. In Table 1, the image density is a value obtained by measuring the black solid image portion of FIG. 2 printed for the first time with a reflection densitometer RD-914 manufactured by Macbeth.

The black solid memory was determined as follows. In the solid black image after the original document of FIG. 2 has been printed four times, the solid black portions 10a, 10b, 10c of FIG.
The part suitable for 10d is a reflection densitometer RD- manufactured by Macbeth.
The average value of the image densities at these four points was defined as E. On the other hand, the white parts 20a, 20b, 20c, 20 of FIG.
The portion matching d is the reflection densitometer RD-91 manufactured by Macbeth.
4 and the average value of the image densities at these four points is defined as F. Then, the value of EF was evaluated as a black solid memory. The value of the above black solid memory indicates that the image has no memory phenomenon as it approaches 0.

Further, the image density and the black solid memory after printing 5,000 sheets of a document having a black-and-white ratio of 6% were evaluated, and the transfer efficiency after printing 5,000 sheets was confirmed. The transfer efficiency was calculated using the following formula.

[0037]

[Equation 1]

In the formula, A is the weight of the magnetic one-component developer replenishing cartridge before printing, B is the weight of the magnetic one-component developer collecting cleaning cartridge before printing, and C is the magnetic one-component developer after printing 5,000 sheets. The weight of the component developer replenishing cartridge, D is the weight of the magnetic one-component developer collecting cleaning cartridge after printing 5,000 sheets.

[0039]

[Table 1]

As can be seen from the results in Table 1, Example 1 using the magnetic one-component developer of the present invention, that is, the base magnetic toner containing the silicone oil, further having the silicone oil adhered to its surface was used. In ~ 7,
The image density after printing 5,000 sheets was 1.34 or more, the black solid memory was 0.21 or less, and the transfer efficiency was 90% or more, which was practically no problem.

On the other hand, the magnetic one-component developer of Comparative Example 1, that is, the one in which the silicone oil is not present in the mother magnetic toner and on the surface thereof has no problem in image density and black solid memory, but the transfer efficiency is considerably high. It was low. As in Comparative Examples 2 to 4, in the magnetic one-component developer only in which the base magnetic toner contains the silicone oil,
It can be seen that although the transfer efficiency is improved as the content of the silicone oil is increased, the image density and the black solid memory are deteriorated. Further, in the magnetic one-component developer in which the silicone oil is simply attached to the surface of the base magnetic toner as in Comparative Examples 5 to 7, the transfer efficiency is improved as the amount of silicone oil attached is increased, but the image density and black are increased. You can see that the solid memory is getting worse.

[0042]

As described above, the magnetic one-component developer of the present invention comprises a base magnetic toner containing a binder resin, a magnetic material and silicone oil, and a silicone oil adhered to the surface of the base magnetic toner. Therefore, the transfer efficiency is excellent, the image density is high, and the memory phenomenon is small. Further, when the content of the silicone oil in the base magnetic toner is 0.1 to 0.5% by weight, the transfer efficiency is further improved, the image density is high and the memory phenomenon occurs even when printing a large number of sheets. Few. Further, when the amount of the silicone oil attached to the surface of the base magnetic toner is 0.01 to 0.1 parts by weight with respect to 100 parts by weight of the base magnetic toner, the transfer efficiency is further improved and a large number of prints are printed. Even when the image density is high, the memory phenomenon is small.

[0043]

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a developing device used in a non-contact type magnetic one-component developing method.

FIG. 2 is a diagram showing an image pattern used for image evaluation in Examples.

[Explanation of symbols]

1 ... Photosensitive drum, 3 ... Magnetic one-component developer, 6 ... Non-magnetic sleeve

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 54-48245 (JP, A) JP 11-202546 (JP, A) JP 10-293410 (JP, A) JP 10- 202133 (JP, A) JP-A-8-334918 (JP, A) JP-A-8-15895 (JP, A) JP-A-6-202461 (JP, A) JP-A-4-119361 (JP, A) JP-A-2-287363 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (4)

(57) [Claims] 1. A binder resin having a base magnetic toner containing a magnetic material and a silicone oil, with the addition of silicone oil to the mother body magnetic toner mother
After applying silicone oil to the surface of the magnetic toner,
A magnetic one-component developer comprising a fine silica powder . 2. The magnetic one-component developer according to claim 1, wherein the content of silicone oil in the base magnetic toner is 0.1 to 0.5% by weight. 3. The amount of silicone oil adhering to the surface of the base magnetic toner is 0.01 to 0.1 part by weight with respect to 100 parts by weight of the base magnetic toner. The magnetic one-component developer according to claim 2. 4. Binder resin, magnetic substance and silicone oil
Silicone oil is added to the base magnetic toner containing
Apply silicone oil to the surface of the base magnetic toner.
Magnetic powder characterized by adding silica fine powder after
Method for producing one-component developer.