JPH025072A - Production of toner for two-component development - Google Patents

Abstract

PURPOSE:To sharpen a charge distribution and to decrease sticking of the toner to the non-image part of a photosensitive body and staining of the inside of an electrophotographic copying device by subjecting toner particles to a heating treatment at the temp. below the glass transition temp. of a binder resin. CONSTITUTION:The toner particles are formed by kneading the binder resin and coloring agent and grinding the mixture and an external additive is added thereto so as to be stuck to the toner particles. The toner particles are then subjected to the heating treatment at the temp. below the glass transition point of this binder resin. The binder resin to be used is exemplified by polystyrene, styrene-alkyl acrylate, etc. The coloring agent is exemplified by, for example, a carbon black, oil black, graphite, etc. The desired electrostatic charge quantity is attained in this way and the excellent charge exchangeability is obtd. The charge distribution is sharp even after toner admixing and the sticking of the toner to the non-image part of the photosensitive body decreases; in addition, the staining in the machine decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing a toner for a two-component developer used for developing an electrostatic latent image in electrophotography, electrostatic recording, and the like.

Conventional techniques In electrophotography, electrostatic recording, etc., electrophotographic developers used to develop electrostatic latent images include resins such as polystyrene, styrene-butadiene copolymer, and polyester, and carbon black. , using a pigment or dye such as phthalocyanine blue as a coloring agent, and after melt mixing,
A toner is obtained by crushing it to 1 μm to 30 μm, and this toner is used as a carrier with glass pieces, iron,
A two-component developer is generally used by mixing particles of nickel, ferrite, etc., or particles coated with various resins.

However, these electrophotographic developers often do not have the desired charging amount, charging speed, charge exchangeability, charging uniformity, environmental dependence of image quality, developer durability, etc. Rollers are added internally or externally as an additive.

Problems to be Solved by the Invention However, simply adding the conventionally used charging controllers 1 to rollers does not necessarily satisfy the above-mentioned requirements.
In a system in which a metal oxide powder of cm to 109 Ω・cm is externally added as a charge controller, the amount of addition that provides the desired amount of charge does not match the amount of addition that provides the desired charge exchange property, and the amount of charge is If it is set to a predetermined value, there is a problem in that the charge exchangeability deteriorates significantly, and more toner adheres to the non-image area of the photoreceptor, resulting in only copies with a lot of fog.

Therefore, the present invention was made with the aim of obtaining an electrophotographic developer that satisfies all of the properties required in the above-mentioned conventional technology, and provides a method for producing a toner for a two-component developer used for this purpose. It's about doing.

In other words, it is an object of the present invention to realize a desired amount of charge, have excellent charge exchangeability, and have a sharp charge distribution even after toner atomization (after mixing additional toner), so that the photoconductor Toner for two-component developer for electrophotographic developer that has extremely little toner adhesion to non-image areas, less dirt inside the machine, excellent durability, and can provide stable image quality even when making multiple copies. The purpose is to provide a method for manufacturing.

Means for Solving the Problems The method for manufacturing a toner for a two-component developer of the present invention involves kneading a binder resin and a colorant, pulverizing them to form toner particles, and adding external additives to form toner particles. The toner particles are then heat-treated at a temperature equal to or lower than the glass transition point of the binder resin.

The present invention will be explained in detail below.

In the present invention, first, toner particles containing a binder resin and a colorant as main components are formed. These toner particles are manufactured by a known method using known ingredients. Binder resins used include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, and styrene-alkyl acrylate copolymer.
Butadiene copolymers, styrene-maleic anhydride copolymers, unsaturated polyester polymers, and graft copolymers of the above polymers with crystalline polymers of monomers selected from ethylene, propylene, and vinyl acetate, etc. I can give you something.

In addition, examples of coloring agents include carbon platter, oil black, graphite, nigrosine dye, aniline blue, calcoyl blue low, ultramarine blue, DuPont oil red,
Quinoline Yellow, Methylene Blue Chloride, Phthalocyanine Blue, Malachite Green Oxalate, Lamp Black, Rose Bengal, C.I. 1. Pigment・
Red 48:1, C. 1. pigment red 122
,C. 1. Pigment Red 57;1, C.I. 1.
Pigment Yellow 97, C. I, Pigment No. Yellow 12, C. 1. Pigmen 1~・Blue 15.1,
C. 1. Pigment Blue 15:3 and the like can be cited as representative examples.

In addition to the binder resin and the colorant, an internal additive may be used as a third component in the toner particles. There are no particular limitations on the internal additive as long as it is a known one, and for example, a charge control agent, a resin for offset prevention such as polyethylene, vopropylene, waxes, etc. can be used.

In the present invention, the above-mentioned components are mixed, heated and kneaded by a conventional method, cooled, and then pulverized to produce toner particles having an average particle size of about 30 μm or less, preferably in the range of 3 to 20 μm.

External additives are added to the obtained toner particles and mixed. As external additives, metal oxide fine particles, silica fine particles, cleaning aids, etc. are used.

Examples of metal oxide fine particles include tin oxide, zinc oxide, aluminum oxide, titanium oxide, and zirconium oxide. These metal oxide fine particles have an electrical resistance of 102
~109 Ω·cm, and preferably has an average particle size of 0.3 μm or less.

The silica fine particles include silica itself, or 1 which is directly bonded to silicon by a silicon-carbon bond as described in Japanese Patent Publication No. 54-16219.
A silicon atom having ~3 organic groups is silicon-oxygen-
Silicon dioxide particles are provided having surface silicon atoms chemically bonded via silicon bonds. The anti-wrinkle particles may be subjected to a hydrophobic surface treatment.

Examples of cleaning aids include fine resin powders such as polymethyl methacrylate, polyvinylidene fluoride, and polytetrafluoroethylene.

These external additives may be added in an amount of 0.0% per 100 parts by weight of toner particles.
It is preferable to add it in a proportion of 1 to 5.0 parts by weight.

Each henna particle with external additives attached to its surface is then heat-treated. The heat treatment can be carried out, for example, by placing the toner particles in a container and keeping them in a constant temperature bath at a predetermined temperature, or by using a hot air fluidized bath. The heat treatment temperature needs to be below the glass transition point of the binder resin used for the toner particles. If the heat treatment temperature is higher than the glass transition point, toner particles will adhere to each other during the heat treatment.

The preferable heat treatment temperature is 2°C or more than the glass transition point.
The temperature range is 15°C lower. When the heat treatment temperature is 15° C. or more lower than the glass transition point, the effect of improving charge exchangeability (atomicity) by the heat treatment decreases.

The toner for a two-component developer obtained as described above is mixed with a carrier and used as a so-called two-component developer.

As a carrier, particles with an average particle size of up to 500 μm are used, including iron, nickel, cobalt, iron oxide, and iron oxide.
-, glass beads, granular silicon, and other known materials are used. Further, the surfaces of these particles may be coated with a coating agent such as a fluorine resin, an acrylic resin, or a silicone resin.

An electrophotographic developer using the toner for two-component developer of the present invention can be used to develop an electrostatic latent image formed on an electrophotographic photoreceptor or an electrostatic recording material. That is, an electrostatic latent image is electrophotographically formed on a photoreceptor made of an inorganic photoconductive material such as selenium, zinc oxide, cadmium oxide, or amorphous silicon, or an organic photoconductive material such as a phthalocyanine pigment or a bisazo pigment; An electrostatic latent image is formed on an electrostatic recording medium having a dielectric material such as poly(ethylene terephthalate 1) using a needle-shaped electrode, and the electrostatic latent image is formed by a developing method such as a magnetic brush method or a cascade method. The toner for the two-component developer is attached to the image to form a toner image. After being transferred to a transfer material such as paper, this toner image is fixed and becomes a copy.

Example The present invention will be explained below with reference to Examples.

Example 1 Polypropylene graft copolymer of propylene polymer and styrene n-butyl methacrylate (weight ratio 80:20) copolymer (10 parts by weight polypropylene 90 parts by weight graft component 54 parts by weight styrene)
n-Butyl methacrylate-I ~ (weight ratio 65:35) crosslinked polymer 36 parts by weight C, 1, Pigment Red 48:1 (Symuler Neothol Red 2BY manufactured by Dainippon Ink & Chemicals ■) 10 parts by weight Melt the above components After cross-mixing, the mixture was finely pulverized and classified to obtain red toner particles having an average particle size of 12 μm.

For 100 parts by weight of this toner particle, the electrical resistance is 8x
1.0 parts by weight of 108 Ω cm tin oxide fine powder, 0.7 parts by weight of silica fine powder, and 0 parts by weight of polymethyl methacrylate powder.
．． After adding 7 parts by weight and mixing for 5 minutes using a Henschel mixer at a circumferential speed of 10 m/s, heat treatment was performed under the conditions shown in Table 1 to obtain red toner (No.

1-1 to No. 1-13) were obtained. In addition, the heat treatment is
The toner was placed in a container, sealed, and placed in a constant temperature bath.

Note that the glass transition point of the binder resin (mixing ratio 54:36) made of a mixture of the above two polymers used in this toner was 55°C.

Example 2 Styrene-n-butyl methacrylate (weight ratio 70:30) copolymer 90 parts by weight Copper tetra(alkylsulfonamide) phthalocyanine 9 parts by weight Silica fine powder
After melting and mixing 1 part by weight of the above acid component, the mixture was finely pulverized and classified to obtain blue toner particles having an average particle size of 13 μm.

For 100 parts by weight of this toner particle, the electrical resistance is 3x
Adding 0.4 parts by weight of 102 Ω・Cm titanium oxide fine powder and 0.8 parts by weight of hydrophobic silica fine powder, 100 g of V
After mixing for 20 minutes using a mold blender at a rotation speed of 20 ppm, heat treatment was performed for 48 hours in a constant temperature bath at 50°C to obtain a blue toner (No. 2-2). In addition, a toner (No. 2-1) that was not subjected to heat treatment was used as a comparative example.

Note that the glass transition point of the binder resin used in this toner was 60°C.

(Comparative test) Each of the toners in Examples 1 and 2 was mixed with a carrier having a ferrite core having an average particle size of 130/1ffl coated with methyl methacrylate-1 to -n-butyl methacrylate copolymer, and A photographic developer was prepared. The mixing ratio was 3.5 parts of toner to 100 parts by weight of carrier.

Next, 100 g of this electrophotographic developer was mixed with 250 n],
The electrophotographic developer was placed in a wide mouth bottle and shaken for 10 minutes using a tumbler shaker, and after stopping, the electrophotographic developer was sampled. Furthermore, 3.5 g of toner was added (+-toner admix), shaken for 30 seconds, and the electrophotographic developer was sampled. The results are shown in Table 1. In the table, regarding the appearance after treatment, ○ means that there is no change from before treatment, × means that it has become lumpy, and in terms of atomicity, Q
is one in which there is no opposite polarity component in the charge distribution after atomicization,
Δ means that the opposite polarity component is less than 3%, and × means that the opposite polarity component is 3% or more.

In addition, separately, toner No. 1-1, No. 1-7,
For No. 2-1 and No. 2-2, put the electrophotographic developer 900 Q into the developing machine of a copying machine (FX-3870, manufactured by Fuji Xerox ■) having a two-component magnetic brush developing machine, and 1 After conducting a continuous copying test of 10,000 sheets,
The results shown in Table 2 were obtained. In the table, Q means that there is no practical problem with fogging or internal contamination, and × means that toner adheres to the non-image area of the copy and the back side of the copy is stained with henna (in-machine contamination).

Effects of the Invention The two-component developer 1 to toner of the present invention improves the charge exchangeability between 1 to 2, and even after additional toner is added (toner atomic mix), the charge distribution is sharp and the photoreceptor remains stable. It exhibits an excellent effect in that the amount of toner side pipes to non-image areas is extremely small, and there is little dirt inside the electrophotographic copying device.

Furthermore, it has excellent durability and can provide images with stable image quality even when a large number of copies are made.

Patent applicant Fuji Xerox Co., Ltd. Agent
Patent attorney Tsuyoshi Watanabe

Claims (2)

[Claims] (1) Knead a binder resin and a colorant, crush them to form toner particles, add external additives and make them adhere to the toner particles,
A method for producing a toner for a two-component developer, characterized in that the toner particles are then heat-treated at a temperature below the glass transition point of the binder resin. (2) The method for producing a toner for a two-component developer according to claim (1), wherein the external additive is silica fine particles or metal oxide fine particles.