JPS61117566A - Dry process toner - Google Patents

Abstract

PURPOSE:To improve fixability and blocking resistance and to obtain excellent electrical characteristics by incorporating inorg. white particles having a specific grain size into a binder resin. CONSTITUTION:The inorg. white particles having 40-300mum average grain size are incorporated at 2-20wt% into the binder resin. >=1 Kinds Al2O3, TiO2, SiO2, MgO and CaO are used for such inorg. white particles. The carbon black- contg. black toner or the color toner colored by dye and pigment into which said inorg. white particles are dispersed and incorporated has the reinforcing effect by the inorg. white particles and is therefore improved in the blocking resistance even if the low melting binder resin having good fixability is used. The obscurity of the iamge owing to the brightness is eliminated by the surface ruggedness formed by the inorg. particles to the fixed image. The inorg. particles has the high effect of controlling electrostatic charge even in the case in which the toner contains the dye pigment to affect the electrical characteristics thereof and therefore the change of the electrical characteristic with age is eliminated and the bleeding of the dye onto the toner surface is suppressed. The staining of the carrier is decreased and the developer life is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dry toner used in electrophotography, laser printers, electrostatic recording, etc.

BACKGROUND ART Conventional dry toners used in electrophotography, laser printers, electrostatic recording, and porcelain printing have the disadvantage that when fixed by a heated fixing roll, the surface of the image becomes glossy and difficult to see.

For this reason, even if attempts are made to lower the nip pressure of the heat fixing roll or to modify the toner binder, fixing failures may occur, and toner blocking problems may occur.

Further, attempts to use color toner instead of carbon black as a coloring agent do not provide a toner with good charging and electrification properties, and there is also the problem that the carrier is contaminated by the dye and the life of the developer is shortened.

OBJECTS OF THE INVENTION Accordingly, the objects of the present invention are to provide a film that has heat roll fixability at relatively low temperatures, good blocking resistance, does not cause surface gloss of the fixed image, and does not have electrical properties deteriorated depending on the type of dye or pigment. First, we searched for long-life materials and found that metal oxides, especially aluminum oxide, titanium oxide, silicon oxide, calcium oxide, magnesium oxide, etc., are the most suitable materials to achieve the purpose of this invention. There was found.

As a result of further studies, it has been found that the above object can be achieved by a dry toner characterized by containing 0.2 to 20% by weight of inorganic white particles having an average particle size of 40 μm or more and 300 μm or less in an adhesive resin. Examples of the inorganic white particles used in the dry toner of the present invention include the following.

Aluminum oxide (HatoOs)% Titanium oxide (TiO
□), silicon oxide (Sin), and Madane oxide are used, but the average diameter of the white particles must be 4 e μm or more and 300 μm or less.

As the binder resin, commonly used styrene,
Ethylene, methyl methacrylate. -Butyl methacrylate, 2-ethylhexyl methacrylate, vinyl chloride, acrylonitrile, α-methylstyrene, 2
-vinylpyridine, butadiene, butyl acrylate,
Homopolymers of vinyl monomers such as propylene, copolymers thereof, polyesters typified by condensates of bisphenol A1 fumaric acid, or graft polymers obtained by polymerizing vinyl monomers in the presence of unsaturated polyesters. used. These binder resins are mixed with the above-mentioned inorganic white particles in an amount of 0.2% to 20%, and carbon black, or in the case of a color toner, a dye or pigment is added in a range of 0.5% to 30%. Then, if necessary, magnetic powder is mixed and kneaded using a three roll or Banbury mixer, rolled, cooled, and then coarsely and finely pulverized to obtain a toner having an average particle size of 10 to 15 μm.

Mix this with carrier powder at a ratio of 1 to 10% by weight and
It may be used as a component developer for electrophotography, laser printer electrostatic recording, or as a single component developer.

It is also effective against Madanetodarafi.

3. The particle size of the inorganic white particles used in the dry toner is preferably 40 μm or more. If the particle size is smaller than that, there is no effect of reducing the gloss of the fixed image. Further, if the diameter is 300 μm or more, the effect on electrical properties is low, and it is particularly difficult to keep the electrical charge stable over time when mixed with carrier powder. In addition, unless the content of inorganic white particles is 0.2% by weight or more, there is no effect on anti-blocking, reduction of gloss, or economical stability of charge amount when mixed with carrier powder, and if 20% or more is contained. Poor electrical properties and fixing properties due to poor crosstalk dispersion during manufacturing are undesirable. Therefore, it is appropriate that the average particle size of the white particles is 40 μm or more and 300 μm or less, and the content is 0.2 weight ratio or more and 20 weight ratio or less. Also, styrene,
Blending resins such as acrylic, polyester, or their graft copolymer resins has no effect, and mixing organic metal salts such as barium laurate, calcium stearate, zinc stearate, etc. with the binder resin has no effect. also has no effect.

Perhaps because these organic compounds have good compatibility and dispersion in the binder resin, they end up being embedded in the binder resin in relatively small amounts, causing the particles to look like inorganic white particles in the example above. It is considered that these do not exhibit the effects of reducing gloss, improving electrical properties, and anti-blocking as expected.

That is, in the dry toner of the present invention, inorganic particles appear moderately on the toner surface as shown in FIG. It is considered that blocking properties and good electrical properties are maintained.

On the other hand, in the case of adding a resin blend or an organic metal salt, Fig. 2(a) shows before heat roll fixing, Fig. 2(b)
) shows the toner after heat roll fixing, it is thought that the blend resin and organic metal salt are buried in the binder resin, so that it is not effective in blocking or improving electrical properties.

The present invention will be explained 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 Plackna 40 (manufactured by Mitsubishi Kasei Co., Ltd.) 80 parts by weight Silicon oxide (Japan Aerosil TT600. Average particle size 40
μm) 2 parts by weight were mixed, kneaded with three rolls, rolled and cooled, and then finely pulverized to give an average particle size of 11 μm.
m toner, carrier iron powder (average particle size 90 μm
) to prepare a developer with a toner concentration of 4, which was charged into a Fuji Xerox 3500 machine to obtain a fixed image. The fixed image had sufficient fixing strength and showed stable image quality even after 50,000 copies were made without any offset.

Furthermore, even when copying a large-area solid image, the image was easy to see without glare.

Comparative Example 1 The composition described in Example 1 above, except for silicon oxide,
When a toner that was kneaded and crushed to a particle size of 11 μm was mixed with iron powder and evaluated in the same manner as in Example 1, the fixing strength was sufficient, but offset occurred frequently and the image was rough. was significant. Further, fogging occurred after 8,000 sheets were printed.

Furthermore, the gloss of the fixed image was clearly greater than that of Example 1.

Example 2 Polynystyl resin (Sanyo Kasei Co., Ltd.! 1000 parts by weight Dia Resin Red K (manufactured by Mitsubishi Kasei) 30 parts by weight silicon oxide (Japan Aerosil TT 600) 258 parts by weight were mixed, cross-wired, and pulverized to obtain an average particle size. A toner with a diameter of 12 μm was obtained. This was then mixed with iron powder and evaluated in the same manner as in Example 1. The fixing strength was sufficient, and there was no offset or gloss of the fixed image. .Also,
The initial image was maintained even after 100,000 copies were made. Further, even when the toner was left at 55° C. for 10 hours, toner blocking did not occur. In addition, silicon oxide (TT600)
.

When the mixed amount was increased to a total of 300 parts by weight, no crosstalk occurred and production was discontinued.

Comparative Example 2 A toner was produced using the composition described in Example 2, but the amount of TT600 was reduced to 20 parts by weight, and the same evaluation was performed. When 500 sheets were printed, the image became thinner.

Evaluation was continued while increasing the toner density, but after 800 sheets, almost no images appeared. Also, the offset was significant, and when left at a high temperature of 55° C., the toner solidified into a cake-like shape in the toner box.

Example 3 The same composition as in Example 2, silicon oxide (TT600
) When a toner was manufactured using silicon oxide having an average particle size of 500 μm, as in Comparative Example 2, a decrease in image density occurred due to an increase in the amount of charged charge.

Similarly, with silicon oxide of 310 μm, although there was a slight tendency for the amount of charge to increase, the initial image density was maintained up to 50,000 sheets. In addition, the surface of the image had no gloss.

Effects of the Invention The dry toner of the present invention has an average particle size of 40 μm or more and 300 μm.
Hereinafter, it is a carbon black colored black toner in which inorganic white particles having a content of 0.2% by weight or more and 20% by weight or less are dispersed at the time of crosstalk, or a color toner colored with a dye or pigment, and (1) inorganic white particles. (2) The surface irregularities formed on the fixed image of relatively large inorganic particles reduce the difficulty of viewing the image due to gloss. (3) Even when the toner contains dyes and pigments that have a significant effect on the electrical properties, the inorganic particles contained have a great charge control effect, so the electrical properties do not change over time, and the dyes do not change over time. Since bleeding is also suppressed by the white particles on the toner surface, carrier contamination is also reduced, and the developer has a long lifespan.

[Brief explanation of the drawing]

FIGS. 1(a) and (bJ are diagrams showing the state of inorganic white particles in the dry toner of the present invention before and after fixing with a heat roll, and FIGS. 2(a) and (b) are resin blends or organic metal particles. It is a diagram showing the state of blend particles or organometallic salt particles in a dry toner to which salt is added, after fixing with a heat roll fixing agent.Symbols in the diagram: 1...Dry toner; Ze...Inorganic white particles: 3...
Blend resin or organic metal salt particles; 4... Transfer paper. 100(a) (a) (b)

Claims (1)

[Scope of Claims] 1) A dry toner characterized by containing 0.2 to 20% by weight of inorganic white particles having an average particle size of 40 μm or more and 300 μm or less in an adhesive resin. 2) The inorganic white particles are aluminum oxide, titanium oxide,
Claim 1 is selected from one or more of silicon oxide, magnesium oxide and calcium oxide.
Dry toner described in section.