JPH0667463A - Production of electrophotographic toner - Google Patents

Abstract

PURPOSE:To improve electrification characteristics by kneading a fixing resin, charge controlling agent, and other compounding material for the toner, pulverizing the kneaded material, classifying to obtain toner particles, and washing the toner particles with a solvent which dissolves the charge controlling agent. CONSTITUTION:A fixing resin, charge controlling agent, and other compounding material for the toner such as coloring agent, mold release agent, etc., are mixed and stirred under conditions to give low-load and low-shearing force. The mixing temp. is preferably lower than the glass transition temp. of the fixing resin. Then the kneaded material is pulverized and classified to obtain the toner particles. The toner particles and a solvent which dissolves the charge controlling agent are mixed in a mixer and stirred to wash the particles. Then the toner is separated from the solvent with a filtering device, and dried in vacuum. By washing the toner surface with a specified solvent, the charge controlling agent exposing on the particle surface can be removed, and the obtd. toner particles have excellent durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrophotographic toner, and more particularly to a method for producing an electrophotographic toner having excellent charging properties.

[0002]

2. Description of the Related Art An electrophotographic toner (hereinafter simply referred to as "toner") contains a fixing resin and a colorant as essential components, and if necessary, various materials such as an organic / inorganic release agent may be added to the fixing resin. The resin particles are dispersed and mixed, and in the production, the above-mentioned toner materials are mixed, the mixture is melt-kneaded, various constituent materials are uniformly dispersed, and cooling, pulverization, and classification are performed to obtain toner particles. It has gained.

Generally, a method of adding a charge control agent is used in order to improve the toner charge amount and stabilize the toner charge.

[0004]

However, if the content of the charge control agent in the toner particles is low, the toner charge rise is poor and the saturated charge amount is also low. On the other hand, if the content of the charge control agent is high, the charge control agent is exposed on the surface of the toner particles, and this is attached to the surface of the carrier and causes the generation of the reverse polarity toner.

Conventionally, various attempts have been made to solve the above problems by variously devising the addition amount of the charge control agent or the addition method of the charge control agent, but a simple and reliable addition method has not yet been found. Therefore, an object of the present invention is to provide a method for producing an electrophotographic toner having excellent charging characteristics.

Another object of the present invention is to provide a method for producing an electrophotographic toner in which the charge control agent is not exposed on the surface of the toner particles even if the content of the charge control agent in the toner particles is increased.

[0007]

According to the present invention, a fixing resin, a charge control agent and other compounding agents for toner are kneaded,
A method for producing an electrophotographic toner comprising the steps of pulverizing a kneaded product, classifying the kneaded product to produce toner particles, and washing the toner particles with a solvent dissolving a charge control agent. It

[0008]

The method for producing an electrophotographic toner of the present invention is the same as the prior art in producing toner particles, but it is remarkable that the toner particles are washed with a solvent that dissolves the charge control agent. Is. That is, in the conventional pulverization method, the charge control agent is inevitably exposed on the toner surface, but according to the present invention, the exposed charge control agent is removed by the solvent by introducing a washing step of treating the toner surface with a predetermined solvent. As a result, toner particles having excellent durability can be obtained.

As the charge control agent, two types of charge control agents for positive charge control and negative charge control are used depending on the polarity of the toner. Examples of the charge control agent of the positive charge control agent include organic compounds having a basic nitrogen atom, such as basic dyes, aminopyrine, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, and the like, and surface-treated fillers with the above compounds. can give.

Examples of the charge control agent for controlling the negative charge include compounds containing a carboxy group (eg, metal chelate of alkylsalicylic acid), metal complex dyes, fatty acid soaps, metal salts of naphthenic acid and the like. The charge control agent is used in a proportion of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the fixing resin.

As the cleaning solvent, any solvent can be used as long as it can dissolve the above charge control agent, but generally, alcohols such as methanol and ethanol can be preferably used. The fixing resin is styrene resin, acrylic resin,
Or styrene-acrylic resin, polyester resin,
Polyurethane resin, silicone resin, polyamide, modified rosin, etc. are used.

As the colorant, a conventionally known colorant can be used. For example, the following colorants can be preferably used. Black furnace black, channel black, gas black, oil black, carbon black such as acetylene black, lamp black, aniline black white zinc white, titanium oxide, antimony white, zinc sulfide red red iron oxide, cadmium red, red lead, mercury sulfide , Cadmium, Permanent Red 4R, Resor Red,
Pyrazolone red, watching red calcium salt,
Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B Orange Red Lead Yellow, Molybdenum Orange, Permanent Orange GTR, Pyrazolone Orange, Vulcan Orange, Indanthrene Brilliant Orange RK, Benzidine Orange G, Indanthrene Brilliant Orange GK Yellow Yellow Lead, Zinc Flower, Cadmium Yellow, Yellow Iron Oxide, Mineral Fast Yellow, Nickel Titanium Yellow, Navels Yellow, Naphthol Yellow S, Hansar Yellow G, Hansar Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake Green Chromium Green, Chromium Oxide, Pigme Togulin B, Malachite Green Lake, Final Yellow Green Blue Navy Blue, Cobalt Blue, Alkali Blue Lake, Victoria Blue Lake, Phthalocyanine Blue Partial Chloride, Farnest Sky Blue, Indanthrene Blue BC, Metal-free Phthalocyanine Blue Purple Manganese Purple, Fast Violet B, methyl violet lake extender pigments include, for example, perlite powder, barium carbonate,
Examples include clay, silica, white carbon, talc, and alumina white.

Examples of the conductive pigment include various metal powders such as conductive carbon black and aluminum powder. Examples of magnetic pigments include triiron tetraoxide (magnetite iron black); iron sesquioxide (γ-Fe2O3), zinc iron oxide (ZnFe2O4), iron yttrium oxide (Y3Fe5O12), iron cadmium oxide (CdFe2O4), iron oxide gallium ( Gd3Fe5O4), iron oxide copper (CuFe2O4), iron oxide lead (PbFe12O19), iron oxide nickel (NiFe2O4), iron oxide neodymium (NdFeO3), iron oxide barium (BaFe12O19), iron oxide magnesium (MgFe2O4), iron manganese oxide (MnFe2O4). ), Various ferrites such as lanthanum iron oxide (LaFeO3);
Examples include iron powder, cobalt powder, nickel powder, and the like.

These pigments may have a plurality of functions. For example, carbon black has a function as a black pigment and a function as a conductive pigment. Similarly, magnetite has a function as a black pigment and a function as a magnetic pigment. It is preferable that these pigments are present in the toner in an amount of 5 to 15% by weight, particularly 7 to 12% by weight, depending on its use.

The method for producing toner particles according to the present invention is as follows.
This is similar to the conventional method for producing toner particles by a pulverization method. For example, a fixing resin, a colorant, a charge control agent, a release agent, etc. are mixed and stirred. The mixing and stirring should be carried out under the condition that a low load and a low shearing force act, and generally, it can be carried out by various mixing and stirring devices such as a conical blender, a ribbon blender, a V-type blender, a Nauta mixer, a Henschel mixer, and a ball mill. The mixing and stirring temperature is preferably lower than the glass transition point (Tg) of the fixing resin.
The required mixing / stirring time varies depending on the type of equipment and the input amount, but generally a range of 10 to 300 minutes is suitable.

The premix thus obtained is melt-kneaded by a conventional method, and the kneaded product is pulverized and classified to obtain toner particles. The toner particles and the solvent are put in a mixer and mixed and stirred. The stirring time varies depending on the input amount, etc.,
Generally, about 30 minutes is appropriate. The washed toner is separated into toner and solvent by a filter, and the toner is vacuum dried. The dryer may be a commonly used one.

The resulting toner particles may be sprinkled with hydrophobic silica fine particles in the mixing stirrer. The toner produced by the production method of the present invention is useful as both a one-component developer and a two-component developer. When it is used as one component, it is used as a toner particle developer containing the above magnetic material. When used as a two-component developer, the toner is a glass bead or oxidized or unoxidized iron powder, an uncoated carrier such as ferrite, or a magnetic substance such as iron, nickel, cobalt or ferrite is used as an acrylic polymer or fluorine. A developer is prepared by mixing with a coated carrier coated with a polymer such as a resin-based polymer, polyester, or a modified silicone resin. The carrier generally has a particle size of 30 to 500 μm. When a two-component developer is used, the toner concentration is preferably 2-15%.

The toner particles have a volume-based median diameter of 5 to 30 μm, especially 5 to 5 by a Coulter counter.
It is preferably in the range of 15 μm.

[0019]

EXAMPLES Hereinafter, the electrophotographic toner of the present invention will be described in more detail with reference to Examples and Comparative Examples. Example 1 Styrene-acrylic resin 100 parts by weight (“S-REC P596” manufactured by Sekisui Chemical Co., Ltd.) Carbon black 10 parts by weight (“Regal 330R” manufactured by Cabot Co.) Charge control agent 3 parts by weight (“Aisenspiron Black TRH” Hodogaya Chemical) Release agent: 1 part by weight (“Viscor 550P”, manufactured by Sanyo Kasei Co., Ltd.) A mixture having the above formulation was premixed with a Henschel mixer, then melt-kneaded with a twin-screw extruder and allowed to cool. This kneaded product was roughly pulverized with a cutting mill and finely pulverized with a jet mill to obtain a minus toner having an average particle size of 10 μm in the range of 5 to 20 μm with an Alpine classifier.

100 g of this toner was placed in a 1 l beaker, and a methanol-hexane mixed solvent (1:99) 0, 8 was added.
1 was added and the mixture was stirred with a stirring rod with motor (100 rpm) for 5 minutes. Next, the solution was filtered with a filter paper, put in a desiccator, and vacuum dried for 8 hours. After the completion of drying, the toner was put into a mixer and crushed.

Next, 0.2 parts by weight of hydrophobic silica fine particles ("Aerosil R972" manufactured by Degussa Co.) were mixed and dispersed in the toner particles to prepare an electrophotographic toner used in the present invention. This electrophotographic toner has an average particle size of 100
A two-component developer having a toner concentration of 3.5% was obtained by uniformly mixing and stirring with a ferrite carrier of μm. A total of 200,000 copies were made from this two-component developer using a copying machine (“DC-4085” manufactured by Mita Kogyo Co., Ltd.). Comparative Example 1 Styrene-acrylic resin 100 parts by weight (“S-REC P596” manufactured by Sekisui Chemical Co., Ltd.) Carbon black 10 parts by weight (“Regal 330R” manufactured by Cabot Co.) Charge control agent 3 parts by weight (“Aisenspiron Black TRH” Hodogaya Chemical) Release agent: 1 part by weight (“Viscor 550P”, manufactured by Sanyo Kasei Co., Ltd.) A mixture having the above formulation was premixed with a Henschel mixer, then melt-kneaded with a twin-screw extruder and allowed to cool. This kneaded product was roughly pulverized with a cutting mill and finely pulverized with a jet mill to obtain a minus toner having an average particle size of 10 μm in the range of 5 to 20 μm with an Alpine classifier.

Next, 0.2 parts by weight of hydrophobic silica fine particles ("Aerosil R972" manufactured by Degussa) was mixed and dispersed in the toner particles to prepare a toner for electrophotography. This electrophotographic toner was uniformly mixed with a ferrite carrier having an average particle diameter of 100 μm and stirred to obtain a two-component developer having a toner concentration of 3.5%. Copy this two-component developer with a copier ("D
C-4085 "manufactured by Mita Kogyo Co., Ltd.) was used to make a total of 200,000 copies. <Evaluation Test> Each test method is as follows. (1) Charge Amount 0.2 g of the developer was sampled, the toner concentration was measured, and then measured with a blow-off charge amount measuring device manufactured by Toshiba Chemical Co., and the charge amount was calculated.

The results are shown in Table 1. Example 1 is superior to Comparative Example 1 in charging stability. (2) Measurement of Fog Density (FD) Using a reflection densitometer, the density of the blank area of the copied image was measured to obtain the fog density.

The results are shown in Table 1. In Example 1, fog did not occur even after copying 200,000 sheets, whereas in Comparative Example 1, fog occurred.

[0025]

[Table 1]

[0026]

According to the present invention, by eliminating the exposure of the charge control agent to the toner surface, it is possible to obtain an electrophotographic toner which is less likely to generate reversely charged toner and has excellent durability.

Claims (1)

[Claims] 1. A step of kneading a fixing resin, a charge control agent, and other toner compounding agents, crushing the kneaded material, and classifying the kneaded material to produce toner particles, and the charge control agent is dissolved in the toner particles. A method of producing a toner for electrophotography, which comprises a step of washing with a solvent.