JPS62209541A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To form an electrophotographic toner superior in fluidity and stability of electrostatic chargeability and good in characteristics in long run test by mixing the toner with a charge controller under the conditions for giving a specified average particle diameter range by applying mechanical stress and burying the charge controller into the surface of the toner. CONSTITUTION:The electrophotographic toner having an average particle diameter of 5-15mum is mixed with the charge controller under the conditions for forming 5-20mum average particle diameter by applying mechanical stress to bury at least a part of the charge controller into the surface of the toner. After the treatment of the toner, it is observed that the small particles of the toner decrease and become more uniform in particle diameter, and the corners of the particles are rounded, i.e. the toner particles small in diameter are made uniform in the prescribed particle diameter by the mixing treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a toner for dry developing electrostatic latent images such as electrophotography.

(Prior art) Conventionally, dry development methods include methods using a two-component developer in which toner particles are mixed with carrier particles, that is, glass beads or magnetic powder, and methods in which a two-component developer is used in which toner particles are mixed with carrier particles, that is, glass beads or magnetic powder, and a method in which magnetism is imparted to the toner particles themselves is used. There is a method using a one-component toner.

Furthermore, recently, a method using a non-magnetic one-component toner with excellent environmental resistance has been proposed.

Conventional methods for manufacturing these toners include thermoplastic resin, colorants such as pigments and dyes, wax, plasticizer,
Additives such as charge control agents are heated and melted, secondary agglomerated pigments are milled by applying strong shearing force, and magnetic powder is heated and melted as necessary to form a uniform composition.

Most of the methods involved pulverizing the material after cooling it and classifying it into two categories.

However, in terms of quality, the toner particles obtained by this pulverization method vary in size and shape, and are generally amorphous, so their triboelectric charging characteristics are different, causing scumming or scattering inside the machine. Furthermore, there are drawbacks such as poor fluidity of the toner, which makes replenishment difficult and causes trouble, and improvements are desired. Also,! ! ! In terms of the manufacturing process, there are problems such as the kneading process requires a large amount of energy and requires two classifications, which requires a large number of man-hours.

To this end, attempts have been made to obtain a one-spherical toner by spray drying and suspension polymerization.

However, in the former case, it is necessary to select a resin that has good solubility in the solution, and there remains a problem in the offset phenomenon to the fixing drum, and in the e method, problems in blocking and offset phenomena remain. Therefore, it has not been industrialized.

In addition, conventional toners use a relatively expensive charge control agent as a toner raw material that originally exhibits characteristics on the toner surface.
It is also contained in the deep part of the toner, which is disadvantageous in terms of cost.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems, and the charge control agent is distributed on the surface of the toner, so that the shape of each particle is rounded (angular) compared to conventional toner. 3), and the particle sizes are relatively uniform, with excellent fluidity and triboelectric properties.

The object of the present invention is to provide a toner that is advantageous in terms of economy.

[Structure of the invention]

(Means for solving the problem) As a result of intensive research, the present inventors found that the average particle size is 5 to 15.
μ toner used in electrophotography.

To provide an electrophotographic toner in which at least a portion of the charge control agent is embedded in the toner surface by mixing the charge control agent with a charge control agent under conditions such that the average particle size is in the range of 5 to 20 μm by applying mechanical strain. It is something. In this specification, particle diameters are measured using a Coulter Counter Model TAn (manufactured by Coulter Electronics Co., Ltd.) on a 1 volume basis.

The toner used in the present invention includes:

It is possible to use the one obtained by the conventional method as it is, or it is possible to use the method of embedding a coloring agent on the resin surface by the same operation as the present invention in the resin particles as described later, and there are no particular limitations. do not have.

Polystyrene resin is used as toner resin.

Copolymers containing styrene with styrene and acrylic esters, methacrylic esters, acrylonitrile or maleic esters, polyacrylic esters, polymethacrylic esters, polyesters, polyamides, polyvinyl acetate, epoxy resins, phenolic resins, hydrocarbon resins.

Examples of binder resins that are known per se include petroleum resins and chlorinated paraffins, and these can be used alone or in combination. Other additives include coloring agents such as pigments and dyes, lubricants such as wax in addition to magnetic powder, and fluidity imparting agents such as colloidal silica.

Low molecular weight polyolefins and the like can be used in combination depending on the purpose, and if they are fine particles, they can be embedded in the same manner as the charge control agent. This operation can be performed simultaneously with, or before or after implanting the charge control agent, depending on the purpose. Further, it is preferable that these toners are substantially free of particles having a size of 25 μm or more. However, it is generally said that fine particles of 5 μm or less are not preferred, but as described later, in the present invention.

Since the grains are sized through the mixing process, there is no need to cut them.

As the coloring agent (B), zinc yellow, yellow iron oxide, Hansa yellow, disazo yellow, quinoline yellow, permanent yellow, red iron oxide.

Permanent Red, Lysol Resodo, Pyrazolone Red, Watchan Resodo Ca Salt.

Watchken Red Mn Salt, Lake Red C.

Lake Red D, Brilliant Carmine 6B.

Brilliant Carmino 3B, navy blue, phthalocyanine blue, gold-free phthalocyanine, and if necessary, colored pigments such as orange, purple, and green, titanium oxide, white and black pigments or dyes such as oil blank may be used. I can do it.

In the present invention, the method of mixing the above-mentioned toner and charge control agent by applying mechanical strain under conditions such that the average particle size is in the range of 5 to 20μ is such that the toner is fused to form a large lump. On the other hand, the conditions are such that the strain force is not too large to cause the toner to be finely pulverized, and at least a portion of the charge control agent is embedded in the surface of the toner. A specific method to satisfy both of these conditions is as follows:
A mortar is used in the laboratory. Industrially, the operating conditions and throughput of dispersing machines such as grinders, ball mills, and sand mills that have similar effects to mortars.

Conditions such as the dispersion medium may be changed so that the above objective is achieved.

However, in a mortar, it takes several hours to several tens of days, and in a ball mill or sand mill, it takes a long time, so industrially, powder is mixed in a fluidized bed state, with a mixer in which the powder moves at high speed with air current, or in an impact mill. It is a mixer that is equipped with blades, hammers, etc. that give

An example of such a mixer is the SI Mill (manufactured by Toyo Ink Manufacturing Co., Ltd., see Japanese Patent Publication No. 57-43051 for an overview).
, Atomizer-2 free crusher (9 Kiku Nara Machinery Works),
An example is a crusher manufactured by Kawasaki Heavy Industries @ (KTM-1).

These devices can be used as they are or modified as appropriate to meet the purpose of the present invention. If possible, a closed system with a circulation system is preferable.

The effect of embedding the charge control agent on the toner surface by such a mixing process is that the toner particles and the charge control agent collide with each other, with two walls, with a dispersion medium such as beads, and instantaneously. It is thought that a phenomenon similar to a mechanochemical reaction in the field of inorganic chemistry has occurred, as the temperature of the air stream in the system rises to near the Tg of the resin, cooling the system. In some cases, it may be necessary to do so. The above phenomenon can be understood by observing electron micrographs before and after premixing.

In other words, before the mixing process, the toner particles with a relatively large particle size distribution and the charge control agent are partially aggregated, and after the process, the surface of the toner is hot and the fine particles of the charge control agent are almost invisible. It becomes a particle that is not easily broken even by a running test in a copying machine.

Therefore, effective control can be performed with a small amount of charge control agent. Furthermore, according to the measurement of the particle size distribution, it is recognized that the average particle diameter becomes larger by one side degree after the mixing treatment.

Further, it is observed that the toner after the treatment has fewer small particles, the particle size is uniform, and the corners of the nine particles are rounded. Namely.

It is considered that the toner particles having a small particle size are sized into particles of a constant size by the mixing process.

Various factors can be considered to obtain the above effect, but according to research by the present inventors, the speed of airflow is the highest, and is preferably several tens of meters/second to several hundred meters/second. .

In the present invention, the particle size of the toner is as follows.

It is preferable that the average particle diameter is in the range of several microns to 20 microns, and substantially no toner with a particle size of 5 microns or less and 25 microns or more is contained. When the amount of toner with a particle size of 5 μm or less increases, fluidity deteriorates and background smear occurs. In addition, if the amount of toner larger than 25μ increases, two images will be mixed together, reducing the commercial value.5 However, in the toner of the present invention, particles smaller than 5μ are sized, so
No special classification is required.

In the present invention, when a -component type magnetic toner is used, a known toner containing magnetic powder may be used, and in some cases, a toner in which magnetic powder is embedded by the same operation as in the present invention may be used. There are no particular restrictions on what can be used as the magnetic powder, but when using the latter method, it is preferable to use fine magnetic powder with an average particle size of 1μ or less, preferably 0.5μ, and various types of ferrite magnetite, hematite, etc. iron, zinc, cobalt and nickel.

It is possible to use materials known per se such as alloys or compounds of manganese, etc. These magnetic powders may be classified depending on the purpose, and surface treatments known per se such as hydrophobic treatment or silane coupling agents can be used. It may also be one that has been subjected to processing.

The charge control agents used in the present invention are known per se, and examples include dyes such as Fettschwarz HBN, Nigrosine Base, Friliant Spirit Zabon Schwarz X, Ceres Schwarz RG, and copper phthalocyanine dyes. Yes, other c, r.

Solvent black 1, 2, 3.5, 7. C4 ■, acid black 123, 22.23.28.42.43.
Dyes such as oil black (C, 1, 26150) and spirone black.

Quaternary ammonium salt, naphthenic acid metal salt.

Examples include fatty acid or resin acid metal soaps and colloidal silica.

The present invention will be explained below using specific examples. The middle part of the example shows parts by weight.

Example 1 Styrene-acrylic resin (manufactured by Sanyo Chemical ■).

88 parts of Hymer SBM-73 (trade name), 5 parts of carbon black and low molecular weight polypropylene (manufactured by Sanyo Chemical Co., Ltd.)
Premix 3 parts (trade name: Vinicol 550P) in a Henschel mixer, melt and knead with a twin-screw extruder, let cool, and coarsely crush this kneaded product with an I-type jet mill. A toner (AI) having a particle size of 25 μm or less and an average particle size of about 10 μm was prepared. This toner contained about 3% of fine particles of 5 microns or less.

100 parts of this toner (Al) and 1 part of a charge control agent (manufactured by Orient Kagaku ■, trade name: Bontron S-34) were premixed in a super mixer at a rotational speed of 25Q Q r pm for 1 minute.

A charge control agent was electrostatically attached to the surface of (A1). Next, this was introduced into a free mill M-3, and the internal rotation speed was set to 500 rpm.

The airflow velocity in the free mill at this time was about 90 m/sec, and the average residence time of the introduced mixture in the system was about 3 seconds, and the mixture discharged to the collector passed through the free mill five times in total. The desired toner was obtained.

The average particle size of this toner particle was 11μ.

There were substantially no particles smaller than 5μ and particles larger than 25μ, and no 9-classification was required.

80 parts of this toner and 720 parts of iron powder carrier (manufactured by Dowa Iron Powder ■, trade name: DSP 128B) were mixed in a ball mill for 1 hour, mixed as a two-component developer, and then used in a commercially available copying machine (Sanda Kogyo Co., Ltd.). (trade name: DC-232) manufactured by Iwata Co., Ltd.), and copies were made continuously on plain paper using a test chart.

In this copying, the fixing properties, charge stability, anti-blocking properties, and anti-offset properties of the toner were extremely good, and in a running image test in which the toner of the present invention was put into the toner replenishment hover bar in the copying machine, Over 10,000 images are maintained that are equivalent to the initial images.

The replenishment of toner was also good.

Example 2 In Example 1, a red organic pigment (Lionol Red) was used instead of carbon black.

A toner was obtained using the same procedure except that Toyo Ink Seisakusho (product name) was used, and the same test was conducted, and it showed excellent effects. There was no phenomenon of pigment filming on the photoreceptor, which is often a problem when used.

Comparative Example 1 Production was carried out by a conventional method using the same raw materials as in Example 2 (however, the charge control agent was 4 parts). That is, after mixing each raw material and premixing with a Henschel mixer,
This is melted and kneaded using a two-wheeled extruder and left to cool.

This mixed material was coarsely pulverized using a Type 1 jet mill to obtain a toner having an upper limit particle size of 25 μm or less and an average particle size of about 11 μm or 5 μm or less.

When this toner was subjected to the same test as in Example 1, 9 when compared with the toner of the present invention, slight fading was observed in solid areas, and a running test revealed a decrease in image density after approximately 5,000 copies. A filming phenomenon of red pigment on the photoreceptor occurred, and a bridging phenomenon was observed in the replenishment hopper.

Example 3 Styrene-acrylic resin (manufactured by Nippon Carbide Industries, trade name: Nikalide-NC-6100) 53 parts, carbon black 2 parts, low molecular weight polypropylene (manufactured by Sanyo Chemical Co., Ltd.,
A toner (A2) having an average particle size of about 10 μm was prepared using 3 parts of Vinicol 550P (trade name) and 40 parts of magnetite (Toda Kogyo type, trade name EPT-500) in the same manner as in Example 1.

This toner contained about 3% of fine particles of 5 microns or less.

98 parts of this toner (A2) and 1 part of a charge control agent (manufactured by Orient Kagaku@, trade name Bontron E-81) were premixed in a super mixer at a rotation speed of 280 Qrpm for 1 minute, and this was mixed in a closed system atomizer. -, and the rotational speed of the internal rotating blade was set to 450Orpm. The airflow velocity at this time was 80 m/sec.

The introduced mixture was retained for 30 seconds and then discharged to a Sunclone collector to obtain toner.

The average particle size of this toner was 12.5 μm, and no particles of 5 μm or less and 25 μm or more were measured.

200g of this magnetic toner was transferred to a commercially available copier (Canon).
A clear image was obtained by copying the test chart onto plain paper using a developing machine (NP-500+Canon (trade name)).

Toner fixability, charge stability and blocking resistance,
The offset resistance was extremely good, and when a running test was performed while adding toner, images equivalent to the initial image were obtained over 50,000 sheets, and no toner bridging phenomenon was observed.

Comparative Example 2 A one-component magnetic toner was obtained by a conventional method using the same raw material as in Example 3 (however, the charge control agent was 4 parts). That is, each raw material is premixed with a Henschel mixer, melted and kneaded with a twin-screw extruder, allowed to cool, coarsely pulverized with a cutting mill, finely pulverized with an I-type jet mill, and then 5 μm with an Alpine classifier. The following fine powder and 2
Particles of 5 μm or more were excluded to obtain a toner with an average particle size of 13 μm.

When the same test as in Example 3 was conducted using this toner, the image density decreased after about 10,000 copies, background smear occurred, and a bridging phenomenon in the hopper was observed.

Example 4 In Example 1, instead of styrene-acrylic resin,
Polyester resin (■Made by Kao.

A toner obtained in the same manner except that KTR-2500 (trade name) was used showed similar good suitability.

(Effects of the Invention) The electrophotographic toner according to the present invention has particles without corners and a surface that is hard to break.

In addition, since the nine particle sizes are relatively uniform, it has excellent fluidity and charge stability, and exhibits good characteristics even in long-term running tests. Also.

Because of this characteristic, it is an excellent toner that is compatible with developing devices that use non-magnetic one-component toners, such as the one disclosed in Japanese Patent Application Laid-Open No. 60-22150, where conventional toners had various problems. be.

Furthermore, it is simpler and more cost-effective than conventional systems.

Claims (1)

[Claims] 1. Electrophotographic toner with an average particle size of 5 to 15 μm and a charge control agent are mixed by applying mechanical strain under conditions such that the average particle size is in the range of 5 to 20 μm, and the charge An electrophotographic toner comprising at least a portion of a control agent embedded in the surface of the toner. 2. The one-component magnetic toner according to claim 1, which uses a toner containing magnetic powder. 3. The non-magnetic one-component toner according to claim 1, which uses a toner that does not contain magnetic powder.