JPH0782243B2 - Dry toner - Google Patents

Description

The present invention relates to a dry toner used for electrophotography, laser printers, electrostatic recording and the like.

2. Description of the Related Art Conventional dry toners used in electrophotography, laser printers, electrostatic recording or magnetography have a drawback that the gloss of the image surface is conspicuous and difficult to see when fixed by a heat fixing roll.

For this reason, the nip pressure of the heating and fixing roll is lowered, fixing failure occurs even if an attempt is made to modify the toner binder, and a problem of toner blocking occurs.

In an attempt to use a color toner instead of a carbon black as a colorant, a toner having good chargeability cannot be obtained.
Further, there is a problem that the carrier is contaminated by the dye and the life of the developer is shortened.

OBJECTS OF THE INVENTION Accordingly, the object of the present invention is to have heat roll fixing suitability at a relatively low temperature, good blocking resistance, no surface gloss of a fixed image, and electrical characteristics depending on the type of dye / pigment. Is to provide a developer having a long life and a long life.

SUMMARY OF THE INVENTION The present inventors have searched for seed materials in order to achieve the object of the previous period, and as a result, metal oxides such as aluminum oxide, titanium oxide, silicon oxide, calcium oxide, magnesium oxide, etc. Proved to be the most suitable material to reach.

As a result of further study, the average particle size of the adhesive resin is 40 nm or more and 300 n
Inorganic white particles of m or less 0.2 to 2 per 100 parts by weight of binder resin
It has been found that the above object can be achieved by a dry toner containing 5.8 parts by weight. Examples of the inorganic white particles used in the dry toner of the present invention include the following.

Aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), magnesium oxide (MgO), calcium oxide (CaO).

These may be used alone or as a mixture of any two or more kinds, but the average diameter of the white particles must be 40 nm or more and 300 nm or less.

As the binder resin, styrene, which is usually used,
Ethylene, methylmethacrylate, n-butylmethacrylate, 2-ethylhexylmethacrylate, vinyl chloride, acrylonitrile, α-methylstyrene, 2
-Vinyl pyridine, butadiene, butyl acrylate,
A homopolymer of each vinyl monomer such as propylene, a copolymer thereof, a polyester typified by a condensate of bisphenol A and fumaric acid, or a graft polymer obtained by polymerizing a vinyl monomer in the presence of an unsaturated polyester. Are used. The inorganic white particles are mixed in an amount of 0.2 or more and 25.8 parts by weight or less with 100 parts by weight of these binder resins, and further, carbon black, or in the case of color toner, a dye or a pigment in a range of 0% to 30%. In addition, if necessary, magnetic powder is mixed and kneaded with a three-roll mill or Banbury mixer, and after rolling, cooling, coarse pulverization and fine pulverization, a toner having an average particle diameter of 10 to 15 μm is obtained. This may be mixed with carrier powder at a ratio of 1 to 10% by weight and used as a two-component developer for electrophotography, electrostatic recording of a laser printer, or as a one-component developer as it is. It is also effective for magnetography.

The particle size of the inorganic white particles used in the present dry toner is preferably 40 nm or more. If the particle size is smaller than that, there is no effect in reducing the gloss of the fixed image. On the other hand, when the thickness is 300 nm or more, the effect is low in electrical characteristics, and it is particularly difficult to keep the charged electric charge stable when mixed with the carrier powder. Also, if the content of inorganic white particles is 0.2% by weight or more, there is no effect on blocking resistance, gloss reduction, economical stability of charge amount when mixed with carrier powder, and when it exceeds 25.8 parts by weight. Poor electrical properties and poor fixability due to poor kneading and dispersion during production are not preferable. Therefore, the average particle size of the white particles is 40 nm.
It is appropriate that the content is not less than 300 nm and not more than 0.2 parts by weight and not more than 25.8 parts by weight with respect to 100 parts of the binder resin. Also, styrene,
Blending a resin such as acrylic or polyester, or a graft copolymer resin thereof has no effect, and similarly, an organic metal salt such as barium laurate, calcium stearate or zinc stearate is mixed with the binder resin. Has no effect. Probably, because of the good compatibility and dispersion of these organic compounds in the binder resin, they are embedded in the binder resin in a relatively small order, and the inorganic white particles as in the above example It is considered to have no effect on the reduction of gloss, improvement of electrical characteristics and anti-blocking as seen.

That is, in the dry toner of the present invention, as shown in FIG. 1 (a), inorganic particles appropriately appear on the toner surface and are retained on the surface as shown in FIG. Therefore, it is considered that the anti-blocking property and good electric characteristics are maintained.

On the other hand, when the resin blend or the addition of the organic metal salt is used, as shown in FIG. 2A showing the toner before heat roll fixing and FIG. 2B showing the toner after heat roll fixing, the blend resin, Since the organic metal salt is embedded in the binder resin, it is considered that it has no effect on blocking and improvement of electrical characteristics.

The present invention will be described below with reference to Examples and Comparative Examples.

Example 1 Styrene-n-butyl methacrylate copolymer resin 1000 parts by weight Diamond black (manufactured by Sumitomo Chemical Co., Ltd.) 10 parts by weight Carbon black # 40 (manufactured by Mitsubishi Kasei) 80 parts by weight Silicon oxide (Japan Aerosil TT600, average particle size) (Diameter 40 nm) 2 parts by weight are mixed, kneaded with 3 rolls, rolled and cooled, finely pulverized to obtain toner having an average particle size of 11 μm, and then mixed with carrier iron powder (average particle size of 90 μm) to obtain toner concentration. A 4% developer was prepared and put into a Fuji Zerox 3500 machine to obtain a fixed image.
The fixed image had a sufficient fixing strength and showed no image offset and showed a stable image even after copying 50,000 sheets. Moreover, even if a large area solid image was copied, the image was free from glare and easy to see.

Comparative Example 1 With the composition described in Example 1 above, except for silicon oxide,
The toner was kneaded and pulverized to have a particle size of 11 μm and mixed with iron powder, and the same evaluation as in Example 1 was carried out. As a result, the fixing strength was sufficient, but offset often occurred, and The storm was overwhelming. Also, fogging occurred on 8,000 sheets. Further, the gloss of the fixed image was obviously larger than that in Example 1.

Example 2 1000 parts by weight of polyester resin (manufactured by Sanyo Kasei Co., Ltd.) 30 parts by weight of DIARESIN RED K (manufactured by Mitsubishi Kasei Co., Ltd.) 258 parts by weight of silicon oxide (Japan Aerosil TT600) were mixed, kneaded and pulverized to obtain an average particle size. A toner having a diameter of 12 μm was obtained. Then, this was mixed with iron powder, and the same evaluation as in Example 1 was carried out.
The offset and fixed images had no gloss. Also, 10
The initial image was maintained even after copying 10,000 copies. Also, 55
Toner blocking did not occur even if left at 10 ° C. for 10 hours. When the mixing amount of silicon oxide (TT600) was increased to 300 parts by weight, kneading could not be performed and the production was stopped.

Comparative Example 2 To 100 parts by weight of the toner of Comparative Example 1, 0.6 part by weight of silicon oxide (Japan Aerosil R972, average particle size 16 nm) was externally added to produce a toner, and the same evaluation was performed.
The fixed image had sufficient fixing strength, but a slight offset was observed. Also, when a large area solid image was copied, the obtained image had glare and was very hard to see.

Example 3 A toner was manufactured using the same composition as in Example 2 but using silicon oxide having an average particle size of 50 nm instead of silicon oxide (TT600). As a result, the image density decreased due to an increase in the amount of charge. There has occurred.

Similarly, with 310 nm silicon oxide, the initial image density was maintained up to 50,000 sheets, although there was a tendency for the amount of charge to increase slightly. In addition, the surface gloss of the image was also non-existent.

The dry toner of the present invention has an average particle diameter of 40 nm or more and 300 nm or less, the content is 0.2 parts by weight or more based on 100 parts by weight of the binder resin, and 25.8 parts by weight or less of inorganic white particles, carbon dispersed and contained at the time of kneading. A black toner colored black or a color toner colored with a dye or a pigment. (1) Due to the reinforcing effect of the inorganic white particles, the blocking resistance is improved even with a low-melting-point binder resin having good fixability, (2) ) The unevenness of the surface formed on the fixed image of relatively large inorganic particles eliminates the difficulty of seeing the image due to glossiness. (3) It was contained even when it contained dyes and pigments that significantly affect the electrical properties of the toner. Since the charge control effect of the inorganic particles is great, there is no change in the electrical characteristics over time, and the white particles on the surface of the toner are also used to suppress dye bleeding, reducing carrier contamination. , Has a feature such that the developer life is prolonged.

[Brief description of drawings]

FIGS. 1 (a) and 1 (b) are views showing states of inorganic white particles in a dry toner of the present invention before and after heat roll fixing,
FIGS. 2 (a) and 2 (b) are diagrams showing a state after the fixing with the heat roll fixing agent of the blended particles or the organic metal salt particles in the dry toner to which the resin blend or the organic metal salt is added. Symbols in the figure: 1 ... dry toner; 2 ... inorganic white particles; 3 ... blended resin or organic metal salt particles; 4 ... transfer paper.

Claims (2)

[Claims] 1. A binder resin obtained by mixing 0.2 to 25.8 parts by weight of inorganic white particles having an average particle size of 40 nm or more and 300 nm or less with 100 parts by weight of a binder resin, and then melt-kneading and pulverizing the mixture. A dry toner characterized in that it contains inorganic white particles. 2. The dry toner according to claim 1, wherein the inorganic white particles are selected from one or more of aluminum oxide, titanium oxide, silicon oxide, magnesium oxide and calcium oxide.