JPH05257316A - Developer for electrostatic charge image - Google Patents

Abstract

PURPOSE:To prevent occurrence of weak bond among toner particles in a state of high temperature and occurrence of image fog and increase of scattering of the toner particles by using the toner particles obtained by treating the surfaces of spherical silica particles in a specified range of particle diameter and attaching these silica particles to the surfaces of the toner particles. CONSTITUTION:The silica particles to be used have an average particle diameter of 0.1-1mmu, and if >1mmu, the silica particles in the developer are not consumed together with the toner but accumulated in the developer and cause image fog. If <0.1mmu, the silica addition effect is not exhibited. The silica particles are added, preferably, in an amount of 0.1-5 weight % of the toner, and if <0.1 weight %, the effect is reduced, and if >5weight%, toner charging itself is hindered and fog is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge image developer used in a developing process such as an electrophotographic method, an electrostatic recording method and an electrostatic printing method, and more particularly to toner particles surface-treated with spherical silica particles. And a developer for an electrostatic image containing

[0002]

2. Description of the Related Art A fluidizing agent used in conventional developers for electrostatic images has a primary particle diameter of 7 to 20 nm (mμ) because the smaller the particles, the higher the fluidity. (For example, JP-A-46-5782 and JP-A-48-47346). Also, JP-A-62-1747
No. 72 has a primary particle diameter of 20 nm (mμ) = 0.02.
Although a toner using a fluidizing agent having a particle size of at least μm is described, examples of the toner include hydrophobic titania 30 nm,
The hydrophobic alumina is, for example, 20 nm, which is considerably smaller than the lower limit of 0.1 μm (100 nm) of the spherical silica particles of the present invention, and is not spherical. Furthermore, the fluidizing agent for this toner requires the use of a large-diameter fluidizing agent and a small-diameter fluidizing agent in combination, and the above-mentioned ones are large-diameter fluidizing agents and small-diameter fluidizing agents have particle sizes. Less than 20 nm,
According to the example, a fluidizing agent having a particle size of 7 to 16 nm, for example, silica particles, has a remarkably small particle diameter as compared with the silica particle diameter of the present invention.

[0003]

If the toner is to be fixed at low temperature, various problems are likely to occur in the copy performance after storage at high temperature. One of them is a phenomenon in which image fog increases in the toner left at high temperature.
The reason for this is that the toner particles weakly bond at high temperature, so that the toner particles agglomerate and some toner particles remain without being triboelectrically charged, and the rise of charging in the developing tank is deteriorated, resulting in image fog (BG). It is expected that the amount of toner will also increase, and the scattering of toner from the developing tank will also increase. The present invention solves these problems.

[0004]

In the developer for electrostatic charge images of the present invention, the surface of the developer is treated with spherical silica particles having an average particle diameter of 0.1 μm to 1 μm, and the toner particles having the spherical silica particles attached to the surface are treated. By using it, the said subject was solved.
The developer of the present invention is suitable for dry development. When the average particle diameter of the spherical silica particles is larger than 1 μm, the developer using the same is not consumed together with the toner during copying and is accumulated in the developer, causing image fog. Further, when the average particle diameter of the spherical silica particles is smaller than 0.1 μm, the effect is small even when added to the toner. Average particle size 0.1
The spherical silica particles having a diameter of 1 μm to 1 μm are preferably contained in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner. If the amount of the spherical silica particles is less than 0.1 part by weight, the effect of addition is poor, and if the amount is 5 parts by weight or more, the charging itself of the toner is hindered and the fog increases again.

The spherical silica particles used in the present invention include
Spherical silica particles having an average particle diameter of 0.1 μm to 1 μm are used. As the spherical silica particles, for example, silica particles having a high purity (for example, a silica content of 99.9% or more) and amorphous silica particles can be used. Specific examples of such spherical silica particles include, for example, Seahoster KE-P.
30 (amorphous silica, silica content: 99.9% or more after firing at 1000 ° C., true specific gravity: about 2, average particle diameter: 0.28
± 0.03 μm), Seahoster KE-P50 (amorphous silica, silica content: 99.9% or more after firing at 1000 ° C., true specific gravity: about 2, average particle diameter: 0.53 ± 0.05 μm)
m), Seahoster KE-P100 (amorphous silica, silica content of 99.9% or more after firing at 1000 ° C., true specific gravity 2, average particle diameter 1.00 ± 0.10 μm), but spherical used in the present invention Of course, the silica particles are not limited to these.

As the toner in the present invention, a toner usually used for a developer for an electrostatic image can be used.
The particle size of the toner is generally 5 to 20 μm. These toners generally include a binder, a colorant, and if necessary, a magnetic material, a charge control agent, an offset preventive agent, and the like as additives. As the binder, for example, a binder resin is used. As the binder resin, generally polystyrene, styrene-acrylic copolymer, polyester, epoxy, polyamide, polymethylmethacrylate, polyvinyl butyral, polyvinyl chloride, polyvinyl acetate, polyolefin, silicone resin, polyurethane, rosin, terpene resin, phenol resin, Xylene resin or the like can be used.

As the colorant, various pigments such as carbon black and nigrosine dye, and dyes can be used. Ferrite, magnetite, and ferromagnetic metals such as iron, cobalt, and nickel, and ferromagnetic alloys such as manganese-copper-aluminum can be used as the magnetic material. As the charge control agent, a quaternary ammonium compound,
Nigrosine, nigrosine base, crystal violet, azo metal-containing dye, chlorinated paraffin, chlorinated polyester and the like may be used. Further, as the offset preventing agent, low molecular weight polyethylene, low molecular weight polypropylene, silicon varnish, etc. can be used. The developer may be a two-component developer, for example, a mixture of toner and carrier, or a one-component developer, for example, a toner containing a magnetic material. The mechanism by which the occurrence of image fog and the increase of toner scattering are prevented by the means of the present invention is not clear, and the present invention is not limited by any theory. If left to stand, the toners will bond loosely (not due to melting of the toners), and the lumps of toner thus formed will not become triboelectric particles when agitated with the carrier in the developing tank, and therefore will not be frictionally charged. Toner particles are also generated, and therefore an accurate charge amount cannot be obtained, and fogging and toner scattering occur, but by treating the surface of the toner particles with silica spherical particles having a particle size larger than ordinary silica, Silica particles enter between the particles, the binding is hindered, secondary aggregation of toner particles does not occur, and as a result, fogging is prevented and toner particles are prevented from flying. Prevention is believed to be possible.

[0008]

EXAMPLES The present invention will now be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the following, "parts" means parts by weight unless otherwise specified. The toner used in the following Examples and Comparative Examples is manufactured as follows.

(Toner Production Example) Binder (UNI-7000, Sanyo Kasei Co., Ltd.) 100 parts Carbon black (MA-100, Mitsubishi Kasei) 5 parts Polypropylene (Viscor 550P, Sanyo Kasei Co., Ltd.) 2 parts Quaternary ammonium salt (P-51, manufactured by Orient Chemical Co., Ltd.) 2 parts were melt-kneaded, cooled, pulverized, and classified to obtain toner particle powder having an average particle diameter of 10 μm.

Example 1 To 100 parts of the toner obtained in the above toner production example, 0.5 part of spherical silica (Seahoster KE-P30, average particle diameter 0.28 μm, manufactured by Nippon Shokubai) silica (R972, manufactured by Nippon Aerosil Co., Ltd.) ) 0.1 part Magnetite (EPT-500, manufactured by Toda Kogyo Co., Ltd.) 0.3 part was mixed with a Henschel mixer to obtain "toner 1".
4 parts by weight of this "toner 1" was mixed with 96 parts by weight of a carrier made of ferrite having an average particle size of 100 µm to prepare a developer, which was referred to as "developer 1". This developer 1 is called "SF
-9400 "(manufactured by Sharp Corporation). The toner used was left at room temperature after being left in an environment of 50 ° C. for 24 hours. The fog value (BG) is Hunter whiteness measured with a whiteness meter before and after copying (the same applies hereinafter). Copies Number Toner 1 to 3 sheets 150 sheets 500 sheets 1000 sheets (Toner scattering) Fog value 0.7 1.2 1.0 1.0 Small and good

(Example 2) Instead of the spherical silica (Seahost P30) of Toner 1 used in Example 1, Nippon Catalyst Co., Ltd., Seahost KE-P50, (average particle size 0.53) was used.
μm) was added in an amount of 1 part by weight to prepare a toner 2 and a developer 2. The test method is the same as in the first embodiment. Number of copies Toner 2 1-3 sheets 150 sheets 500 sheets 1000 sheets (toner scattering) Fog value 0.7 1.1 0.9 0.9 Low and good

(Comparative Example) Toner 3 and developer 3 were prepared by removing the spherical silica in the above example. Fifty
The same test was performed after leaving it at 24 ° C. for 24 hours. Fog and toner scattering increased. Number of copies Toner 3 1-3 sheets 150 sheets 500 sheets 1000 sheets (toner scattering) Fog value 0.7 2.5 2.6 2.6 Large and defective

Example 3 The effect of the amount of spherical silica particles added was investigated. The fog (BG) value was investigated by changing the amounts of spherical silica and Seahoster P-30 in Example 1. Amount of Seahoster P-30 0.05 part 0.1 part 0.5 part 5 part 10 parts Fog when copying 500 sheets 2.6 1.5 1.0 1.6 3.0 Less than 0.1 part is less effective, and above 5 parts, silica does not charge the toner itself. It hindered it and the fog rose again. Fog of spherical silica particles and fog The relationship between the particle diameter of spherical silica particles and the occurrence of fog was investigated and the experimental results were as follows. Example 1 except that the spherical silica of Example 1 was replaced with the spherical silica of Table 1 below.
A toner surface-treated with spherical silica particles was prepared in accordance with the above procedure, and the developer performance thereof, in particular, the occurrence of image fog after copying 500 sheets was examined. The results are as follows. Type of spherical silica Primary particle size (μm) BG (500 sheets) Rating R972 0.016 3.0 No effect (Nippon Aerosil Co., Ltd.) OX50 0.040 2.1 Same as above (same as above) Seahoster KE-P30 0.28 1.0 Effective (manufactured by Nippon Shokubai) Seahoster KE-P50 0.53 1.0 Same as above (same as above) Seahoster KE-P100 1.00 1.3 Same as above (same above)

[0014]

According to the present invention, the surface treatment of the toner particles with spherical silica particles larger than those in the prior art can prevent weak bonds between the toner particles in a high temperature state, thereby preventing image fog. It is possible to prevent the occurrence of toner generation and the increase of toner scattering. In addition, the fluidity of the toner is improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takeaki Ouchi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Corporation (72) Hiroshi Sakita 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Toshihiko Murakami 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture

Claims (2)

[Claims] 1. The toner particles have an average particle diameter of 0.1 μm on the surface thereof.
A developer for electrostatic charge images, which is treated with spherical silica particles having a particle size of ˜1 μm. 2. The electrostatic image developer according to claim 1, wherein the spherical silica particles are contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the toner.