JP2850127B2 - Image forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming method using an electrophotographic toner and a developer for developing a latent image in electrophotography.

<Conventional Technology> As a developing toner in an electrostatic image development in an electrophotographic apparatus, a one-component toner using no carrier or a two-component toner using a carrier is used.

 These toners are usually manufactured as follows.

First, a resin, a wax, a pigment, a charge control agent and the like are mixed, melt-kneaded and cooled, and then pulverized and classified to obtain charged toner particles. A fluidizing agent, a resistance controlling agent, and the like are externally added to the charged toner particles, and mixed with a Henschel mixer or the like to adhere the fluidizing agent to the toner surface.

However, in the conventional electrophotographic toner manufactured as described above, if tens of thousands of copies are continuously made, the image density changes with time, fog increases, and the inside of the apparatus is stained.

This is considered to be due to insufficient charge stability, charge rising characteristics, and fluidity of the toner.

Japanese Patent Application Laid-Open No. Sho 62-209542 discloses an invention for improving the fluidity and charge stability of a toner, which is described in Japanese Patent Application Laid-open No. 62-209542. An electrophotographic toner which is obtained by mixing under a condition where a fine particle having a diameter of 5 to 20 μm and substantially 5 μm or less does not exist by applying a mechanical strain force ”. In this case, the change in image density and fog during continuous copying are reduced.

<Problems to be Solved by the Invention> However, with the toner disclosed in the above publication, the problem of in-machine contamination that occurs when tens of thousands of copies are continuously made has not been solved yet.

This is presumably because the rise of the toner charge at the time of toner supply is not sufficiently fast.

The present invention is directed to an electrophotographic toner and a developing method, in which a change in image density and fogging during continuous copying are reduced, and in particular, contamination in a machine is reduced, as a result of rapid rise of charging of the toner, and excellent charging stability and fluidity. It is an object of the present invention to provide an image forming method using an agent.

<Means for Solving the Problems> Such an object is achieved by the present invention described below.

5-20% of particles having an average particle diameter of 5 to 20 μm and a particle diameter of 5 μm or less in number distribution, 1 to 10% by volume of particles having a particle diameter of 2 or more and containing a charge control agent The raw material chargeable toner particles have an average particle size of 5 to 20 μm, particles having a particle size of 5 μm or less increase, and particles having a particle size of 5 μm or less exist in a number distribution of 6 to 25%. The charged toner particles are mixed by applying a mechanical strain force so that the particle diameter becomes 1 to 10% by volume, silica is externally added thereto, and the electrons containing the charged toner particles are mixed. An image forming method using an electrophotographic developer containing a photographic toner and carrier particles, wherein more than 60,000 copies are made without cleaning inside the machine.

<Operation> In the present invention, the raw material chargeable toner particles are mixed by applying a mechanical strain force so that particles having a particle size of 5 μm or less increase. As a result, the corners of the pulverized toner are sharpened, become smooth spheres, the contact area with the carrier or the like is increased, the charging is quickly started, and the charging properties and fluidity are improved.

On the other hand, in the invention described in Japanese Patent Application Laid-Open No. 62-209542, mixing is performed by applying a mechanical strain force so that particles having a particle size of 5 μm or less are substantially absent. It is considered that the property is still insufficient and the rise of charging is not sufficiently rapid.

<Specific Configuration of the Invention> The raw material chargeable toner particles of the present invention exhibit a particularly high effect when applied to known chargeable toner particles for two-component developers.

The volume average particle diameter of the raw material chargeable toner particles used is 5 to 20.
μm, especially 6 to 18 μm, more preferably 8 to 12 μm.

If the average particle size is less than 5 μm, fogging is deteriorated and cleaning is poor, which is disadvantageous in cost.

On the other hand, when the thickness exceeds 20 μm, there is a problem that the resolution is deteriorated and the toner scatters.

The volume average particle diameter may be measured by a Coulter counting method, and the 50% average particle diameter of the measured particle diameter may be determined.
At this time, Isoton II (manufactured by Coulter Electronics Co., Ltd.) was used as the electrolytic solution.
What is necessary is just to measure with a coulter counter TA-II (made by the company) of μm.

Further, as for the particle size distribution, 5 μm or less in the number distribution is about 5 to 20%.

When the average particle size is defined as 2 or more, about 1 to 10% by volume.

By using the toner having such a particle size distribution, the yield and yield of the toner are improved, and the production is facilitated.

The raw material chargeable toner particles have a substantially spherical outer shape when observed with an electron microscope, but have irregularities on the surface and are in the form of crushed fragments.

An appropriate polarity may be selected for the charging polarity of the raw material chargeable toner particles depending on the material of the photoreceptor to be used, the developing process, and the like.

The raw material chargeable toner particles are made of a resin containing a resin and a colorant, and further contain a charge control agent, a wax, and the like as needed.

The resin used for the raw material chargeable toner particles may be selected from known resins according to a fixing method such as heating or pressure bonding, and is not particularly limited, and examples thereof include the following.

Olefin resin, acrylic resin, styrene copolymer,
One or more of various resins such as vinyl resin, polyamide resin, alkyd resin, epoxy resin, and polyester resin.

Of these resins, styrene-acrylic resins and polyester resins are preferred, and styrene-acrylic resins are particularly preferred.

The colorant may be selected according to the purpose, and is not particularly limited. Suitable coloring agents include, for example, the following.

Black pigments such as carbon black, acetylene black, channel black, and aniline black; yellow pigments such as Dialite Yellow GR and Variotor Yellow 1090; red pigments such as permanent red E5B and rhodamine 2B; blue pigments such as copper phthalocyanine and cobalt blue Green pigments such as Pigment Green B; orange pigments such as pyrazolone orange;

The content of such a coloring agent depends on the amount of the resin 100 of the toner particles.
It is preferably about 1 to 10 parts by weight based on parts by weight.

It should be noted that such a colorant may not be used, or in addition, a magnetic powder may be used as a colorant to form a one-component or magnetic toner.

The charge control agent is added as needed to control the charge polarity, charge amount, and the like. In the present invention, an appropriate known charge control agent may be selected according to the intended polarity, charge amount, and the like, and there is no particular limitation. For example, metal complex salt azo dyes, nigrosine dyes and the like can be mentioned, and these are selected according to required characteristics.

The content of such a charge control agent is preferably about 0.1 to 5 parts by weight based on 100 parts by weight of the resin of the raw material chargeable toner particles.

Wax is added as a release agent as needed to prevent offset. In the present invention, the wax used is not particularly limited, and various known waxes, for example, polyethylene wax, polypropylene wax, silicon wax, etc. may be used, and these are selected according to required characteristics. The content of such a wax is preferably about 1 to 7 parts by weight based on 100 parts by weight of the resin of the non-magnetic toner particles.

In addition, if necessary, when magnetic toner particles are used, the magnetic powder contained therein is not particularly limited, and known magnetic powders such as magnetite and various ferrites may be used, but these may be selected according to required characteristics. Is what is done.
Such magnetic powder is preferably contained in an amount of about 5 to 70 parts by weight based on 100 parts by weight of the resin of the magnetic toner particles.

The raw material chargeable toner particles may contain a resistance adjuster and the like in addition to the above.

The raw material chargeable toner particles may be manufactured by an ordinary toner manufacturing method, and for example, manufactured as follows.

The necessary additives are selected from the above-mentioned colorants, charge control agents, waxes and other additives as internal additives, and these predetermined amounts and resins are melted and kneaded, and after cooling,
Coarsely pulverized with a hammer mill, cutter mill, or the like. Next, after finely pulverized by a jet mill, ang mill, etc.,
Classification is performed so as to be within the above-mentioned volume average particle size range to obtain raw material chargeable toner particles.

In the present invention, the raw material chargeable toner particles having an average particle size of 5 to 20 μm as described above are mixed with an average particle size of 5 to 20 μm,
In order to increase the number of particles having a particle size of m or less, mixing is performed by applying a mechanical strain force. The average particle size of the charged toner particles after mixing is 5 to 20 μm, preferably 6 to 18 μm, and particularly preferably 8 to 12 μm.

The mechanical strain force is to apply mechanical energy, mainly impact force, between particles to cause a mechanochemical reaction in some cases.

As an apparatus for applying such a mechanical strain force, for example, there is a granular material processing apparatus as described in JP-A-63-42728, etc., specifically, manufactured by Hosokawa Micron Corporation. A mechanofusion system and a hybridization system manufactured by Nara Machinery Co., Ltd. are suitable.

These devices, for example, by rotating the casing containing the powder at high speed to form a powder layer on the inner peripheral surface, at the inner peripheral surface of the casing, apply compression or friction to the powder layer, At the same time, scraping, dispersion and stirring are performed.

In this case, in the above apparatus, the mixing time is about 15 to 30 minutes, the casing rotation speed is about 800 to 1200 rpm, and the temperature is 15 to
The temperature may be about 50 ° C., and other conditions may be normal.

The charged toner particles mixed under such mechanical strain are spherical particles having a smooth surface when observed with an electron microscope.

Further, in the electrophotographic toner of the present invention, particles having a particle size of 5 μm or less in the number distribution are 6 to 25 in the charged toner particles.
% Exists.

 In addition, the thing of 2 or more particle diameters is 1 to 10 volume%.

If it is less than the above range, the smoothness and spheroidity of the particle surface are insufficient, and the charge rising characteristics are not sufficient. Conversely, if it exceeds the above range, disadvantages such as deterioration of smoothness and spheroidity occur.

The charged toner particles mixed by the mechanical strain force in this manner may be used as it is as an electrophotographic toner by adding necessary external additives described below as needed.

Alternatively, charged toner particles mixed by mechanical strain and charged toner particles not mixed by mechanical strain may be mixed and used.

In this case, in all the charged toner particles, the charged toner particles mixed by mechanical strain force are 60% by weight or more, in particular,
It preferably accounts for 80% by weight or more.

When such a mixed toner is used, the external additive may be added to either one of the toners, or may be added to both of the toners.

To such toner particles, inorganic or organic fine particles such as a resistance adjusting agent, a colorant, and a fluidity improver are externally added as additive particles.

Examples of these are colloidal silica, titanium oxide,
Metal oxides such as zinc oxide and alumina; inorganic fine particles such as silicon carbide, calcium carbonate, barium carbonate, and calcium silicate; magnetic particles; polymer beads such as PMMA, polyethylene, nylon, silicone resin, phenolic resin, benzoguanamine resin, and polyester; Fluorinated organic fine particles such as polytetrafluoroethylene, polytetrafluoroethylene, and polyvinylidene fluoride; fatty acid metal salts such as zinc stearate and magnesium stearate; black pigments such as carbon black, acetylene black, channel black, and aniline black; Yellow pigments such as Dialite Yellow GR and Variore Yellow 1090, red pigments such as Permanent Red E5B and Rhodamine 2B, blue pigments such as copper phthalocyanine and cobalt blue, and Pigment Green B Green pigments, orange pigments such as pyrazolone orange, and the like charge control agent, but in the present invention as an essential component silica.

In addition, only one kind of these additive particles may be used, but if necessary, two or more kinds can be used in combination.

 A release agent can also be externally added as additive particles.

 These additive particles are dry mixed with the toner particles.

At this time, each additive particle may be subjected to a titanate-based, aluminum-based, silane-based coupling agent, silicone oil, other organic treatment, or inorganic treatment for surface hydrophobization treatment and surface dispersion improvement treatment. it can.

These additive particles have an average particle size of about 0.005 to 5 μm. The external addition amount is about 0.1 to 8% by weight.

When the particle size is 1 μm or less, the particle size is measured by an electron microscope.

Such additive particles are dry-mixed with the toner particles by a Henschel mixer, a grind mixer, a V blender, a Nauta mixer or the like, and are adsorbed or fixed on the toner particle surfaces, and further, due to mechanical strain or heat. , Which are fixed and integrated on the surface of the toner particles.

The charged toner particles to which such an external additive has adhered are:
It may be used as a component-based electrophotographic toner.

The electrophotographic toner of the present invention is used as a two-component developer by mixing with carrier particles. At this time, the effect of the present invention is further enhanced.

The carrier particles to be used are not particularly limited, and known carrier particles composed of Fe, various ferrites, and the like may be used. However, ferrite is preferably used because charging control is easy.

In the present invention, the volume average particle size of the carrier particles is preferably 20 to 120 μm, and more preferably 50 to 100 μm.

In the electrophotographic developer of the present invention composed of such carrier particles and the electrophotographic toner,
The content of the electrophotographic toner is preferably 2 to 12% by weight, and more preferably 3 to 10% by weight.

Such an electrophotographic developer of the present invention exhibits a predetermined effect when used in a magnetic brush developing method or, if necessary, in a dry developing method such as a cascade method, a bristle brush method, or a powder cloud method.

<Example> Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention.

Styrene-acrylic resin (KB-1010 manufactured by Mitsubishi Rayon Co., Ltd.) 86 parts by weight Polypropylene wax (Viscole manufactured by Sanyo Chemical Industries, Ltd.)
550P) 4.5 parts by weight Charge control agent (Spilon Black TRH manufactured by Hodogaya Chemical Co., Ltd.) 2 parts by weight 7.5 parts by weight of carbon black (MA-100 manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) blended, melted, kneaded, cooled, and hammer milled And coarsely pulverized. Then, it is finely pulverized by a jet mill and classified, and 6% (almost 0% by volume) of particles having a particle diameter of 5 μm or less in a number distribution having a volume average particle diameter of 11.37 μm contains 1.2% of particles having a particle diameter of 2 or more. Raw material chargeable toner particles containing about 30% by volume were prepared.

The raw material chargeable toner was used as an electrophotographic toner by the following method. After that, the ferrite carrier (TDK T
F-3044 average particle size 100 μm, Hc 18 Oe at 5000 Oe, σm 40e
mu / g) and a life test was performed using a commercially available copying machine (BD-7610 manufactured by Toshiba Corporation) as a developer having a toner concentration of 4%.

Example 1 The raw material chargeable toner was mixed by mechanical strain to prepare a base toner. In this case, the mixing was performed by a method of compressing and scraping the powder on the inner peripheral surface of the rotary casing as described above, and the mixing time was 20 minutes and the rotation speed was 1000 rpm.

As a result, the volume average particle size becomes 11.17 μm, and particles having a particle size of 5 μm or less in the number distribution are 12% (0.3 to 0.4%).
% By volume). In addition, particles having a particle size of 2 or more
The content was 1.1% by volume, and the surface smoothness and the spherical shape were improved by observation with an electron microscope.

Separately, 4% by weight of silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was added to the above-mentioned charged toner, and mixed with a Henschel mixer to prepare a conc. Toner.

The base material toner and the conc toner were mixed at a ratio of 9: 1 with a V blender to obtain a toner. This is referred to as toner 1.

Comparative Example 1 The above-mentioned charged toner and raw material toner were mixed at a ratio of 9: 1 with a V blender to obtain a toner 2.

Comparative Example 2 Toner 3 was obtained in the same manner as in the production of Toner 1, except that the mixing time due to mechanical strain was changed to 20 minutes, and the number of revolutions was changed to 500 rpm.

The volume average particle size of the toner 3 is 12.25 μm, and particles having a particle size of 5 μm or less in the number distribution are 4.2% (almost 0%).
(Volume%), and particles having a particle size of 2 or more were 1.6 volume%. In addition, the smoothness and the sphericality of the toner 3 were improved as compared with the toner 2, but were inferior to the toner 1.

With respect to each of the toners 1 to 3, the image density, charge amount, fog, and in-machine stain were measured at the initial stage and after continuous copying of 40,000 and 60,000 sheets.

 Table 1 shows the above results.

From Table 1, it is clear that the toner 1 has a stable image density, charge amount and fog. Particularly, the in-machine stain and the fluidity are greatly improved as compared with the toners 2 and 3, and very good results are obtained. Can be

Further, the results obtained by performing ball mill stirring on the toners 1, 2, and 3 and measuring the rise of charging are shown in FIG.

The measurement of the toner concentration, carrier and charge in FIG. 1 was performed under the same conditions as in Table 1.

From FIG. 1 and Table 1, it can be seen that the toner 1 shows a favorable rise in charging. It can be seen that this contributes to stabilization of image density and the like, particularly to reduction of in-machine contamination.

<Effects of the Invention> As described above, the toner for electrophotography of the present invention has a rapid charge rise, and has excellent charge stability and fluidity. As a result, during continuous copying, there is little change in image density and fog. In particular, it has the effect of reducing in-machine dirt.

[Brief description of the drawings]

FIG. 1 is a graph showing the charge rising characteristics of the electrophotographic toner of the present invention.

Continuation of front page (72) Inventor Yukio Takahashi 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TEDK Corporation (56) References JP-A-63-235595 (JP, A) JP-A-63-235954 ( JP, A) JP-A-63-235955 (JP, A) JP-A-63-235956 (JP, A) JP-A-63-235957 (JP, A) JP-A-1-221759 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) G03G 9/08 G03G 15/08 507

Claims (1)

(57) [Claims] 1. An average particle diameter of 5 to 20 μm, 5 to 20% of particles having a particle size of 5 μm or less in a number distribution, and 1 to 10% by volume of particles having a particle size of 2 or more. The raw material chargeable toner particles containing the control agent have an average particle size of 5 to 20 μm, particles having a particle size of 5 μm or less increase, and particles having a particle size of 5 μm or less in the number distribution are 6 to 25%. 1 to 10% by volume with 2 or more particle size
To obtain charged toner particles by applying a mechanical strain force, externally adding silica thereto, and an electrophotographic toner containing the charged toner particles,
An image forming method in which more than 60,000 copies are made without cleaning inside the machine, using an electrophotographic developer containing carrier particles.