JPH03220565A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To obtain the toner applicable to a plain paper copying system as well by fixing a nonferrous metal oxide or ferrous/nonferrous metal oxide having a small electrical conductivity as a black coloring agent onto the surfaces of thermoplastic resin particles. CONSTITUTION:This toner is formed by fixing the black nonferrous metal oxide or ferrous/nonferrous metal oxide mixture having <=0.5mum grain size and >=5X10<6>OMEGAcm specific volume resistivity value alone or together with the fine particles of a charge control agent and other necessary particles to the surfaces of the thermoplastic resin particles having 1 to 15mum average grain size. The specific volume resistivity of the toner does not, therefore, degrade as compared with the coloration by the carbon black. The toner which can be applied to the plain paper copying system is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a powder toner for developing electrostatic latent images in electrophotography, electrostatic recording, and the like.

(Prior art) As a powder toner for converting an electrostatic latent image into a visible image,
A common method is to disperse dyes, pigments, Tl1l powders, etc. in a toner resin by melt-kneading, mechanically crush the resulting mixture after cooling, and then classify it.

However, since the so-called pulverized toner obtained by this method has an amorphous shape, it has been pointed out that it has drawbacks such as difficulty in obtaining a uniform charge and poor fluidity.

Furthermore, in manufacturing, the consumption of electrical energy required for melting, kneading, and pulverization is enormous, and methods other than the pulverization method are being considered to obtain powder toner.

Spray drying, emulsion polymerization, suspension polymerization, interfacial polymerization, and the like are known as methods for producing powder toners other than the so-called pulverization method, which involves the above-mentioned melt-kneading and subsequent pulverization.

However, the method of manufacturing by spray drying produces spherical toner, which provides uniform charge and good fluidity, but requires explosion-proofing of the spray dryer and recovery of solvent. However, there are drawbacks such as the large amount of thermal energy consumed during drying, and the fact that the solvent remains in the toner even after drying and is difficult to remove. Due to restrictions on materials, it is difficult to obtain toner with sufficient properties using this method alone.

In addition, by emulsion polymerization method, suspension polymerization method, interfacial polymerization method, etc.
In the method of producing spherical toner particles in water, the dispersant and stabilizer used during the production of toner particles in water remain on the surface of the toner particles, which absorb moisture in the air and reduce the electrical resistance of the toner. It has been pointed out that this method has disadvantages such as making it difficult to copy on plain paper and making the charge on the toner surface non-uniform, which is the biggest problem and it has not yet been put into practical use.

Under the above circumstances, in order to improve the drawbacks of the so-called pulverization method, in addition to the various methods mentioned above, in recent years, for example, Japanese Patent Application Laid-Open No. 6
2-209541, 63-2075, 6331
As shown in various publications such as No. 8570, toners have been proposed in which colorants and other necessary fine particles are fixed to the surfaces of thermoplastic resin particles. However, the toner obtained by this manufacturing method has the following problems and has not yet been put into practical use.

In other words, plain paper copying (P
In order to apply it to the P C) method, the volume resistivity of the toner must be at least 10'3Ω0 or more, but since carbon black, which is usually used as a black colorant, is electrically conductive, it has a blackness that is sufficient for practical use. If the amount of toner used is a distant relative, the volume resistivity of the toner will decrease, resulting in background smearing, or in severe cases, poor transfer. In addition, triiron tetroxide (iron black), which is known as a black pigment in addition to carbon black, has a relatively small volume resistivity value of about 10'Ω or less, and has low tinting power, so it is difficult to obtain sufficient blackness. In order to obtain this, it is necessary to increase the amount added. Therefore, the volume resistivity of the toner decreases in the same way as when carbon black is used.

(Problems to be Solved by the Invention) The present invention provides a toner in which a black colorant is fixed on the surface of thermoplastic particles, which can also be applied to a plain paper copying system.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a black color having a particle size of 0.5 μm or less and a volume resistivity value of 5×10′Ω or more on the surface of thermoplastic resin particles having an average particle size of 1 to 15 μm. The present invention relates to the above-mentioned toner for developing an electrostatic image, characterized in that it is formed by fixing a non-ferrous metal oxide or an iron/non-ferrous metal mixed oxide alone or together with a charge control agent and other necessary fine particles.

The electrostatic image developing toner of the present invention contains a non-ferrous metal oxide or an iron/non-ferrous metal mixed oxide as black colorant fine particles. CuCrz04 (C,1
, pigment blank28), and FezTiO4 (C, I.

Pigment blank 12), Cu (Cr, Fe)
z04(C0f.

Pigment Black 23), (Fe, Mn) (Fe
, Mn)zOn(C,l, Pigment Black 26)
, C,1, pigment blank 27, etc.

These nonferrous metal oxides or iron/nonferrous metal mixed oxides are made into fine particles of 0.5 μm or less. Particles larger than this have low coloring power and are insufficiently fixed to the surface of the thermoplastic resin particles.

The amount of metal oxide black colorant used is 10 parts of thermoplastic resin particles.
The amount is 2 to 20 parts by weight, preferably 5 to 10 parts by weight, and if it is less than the above value, the toner will not be sufficiently colored, and if it exceeds the above value, the electrical resistance of the toner will decrease, which is not preferable.

In the present invention, the volume resistivity value of the non-ferrous metal oxide or iron/non-ferrous metal mixed oxide is 5 x 10'Ω or more, and if it is smaller than this value, the resistance of the toner will decrease and the charge will become uneven, so it should be used on plain paper. transfer becomes difficult.

Resins that can be used for the thermoplastic resin particles of the present invention include those that have the function of holding colorants, magnetic powder, etc. and fixing visible images on paper, such as ethylene-vinyl acetate copolymer, polystyrene-based , styrene-containing copolymers of styrene and acrylic esters or methacrylic esters, acrylonitrile or maleic esters, polyacrylic ester-based, polymethacrylic ester-based, polyester-based, polyamide-based, polyvinyl acetate-based, epoxy-based , phenolic, hydrocarbon,
Petroleum-based resins can be exemplified, and these can be used alone or in combination.

Note that the thermoplastic resin particles may contain magnetic powder depending on the applied development process. The magnetic powder mentioned here may be alloys or compounds of iron such as various ferrites, magnetites, hematites, zinc, cobalt, nickel, manganese, etc. These magnetic powders are spherical, cubic, octahedral, acicular, oblate, etc., and have a shape of 0.05~
It is preferable to have an average diameter of 1.0 microns, and it should be surface-treated to ensure good dispersion in the resin, such as hydrophobic treatment with fatty acids, silane coupling agent treatment, resin coating treatment, etc. There may be.

The thermoplastic resin fine particles used are fine particles produced by a suspension polymerization method, a soap-free emulsion polymerization method, an emulsion polymerization method, a dispersion polymerization method, etc., or particles produced by a dissolution/precipitation method, a spray drying method, etc. Alternatively, amorphous fine particles obtained by melting and kneading them as necessary and pulverizing them with a crusher etc. may be used.The particle size of these resin fine particles is not particularly limited, but the average particle size The diameter is preferably 1 to 15 μm, particularly preferably 3 to 10 μm.

The electrostatic image developing toner of the present invention can be produced using various known methods. Preferably, a media stirring mill having a spherical dispersion medium, such as a sand mill, attritor, pearl mill, or ball mill, is used, and thermoplastic resin particles, a black colorant, other charge control agents, lubricants, abrasives, etc. are added as necessary. The surface of the thermoplastic resin particles is softened by impact force, shear force, friction force, etc., and these fine particles are fixed.

(Operations and Effects of the Invention) According to the present invention, a non-ferrous metal oxide or iron/non-ferrous metal oxide with low conductivity is fixed on the surface of the thermoplastic resin particle as a black coloring agent, so compared to coloring with carbon black. The volume resistivity of the toner does not decrease. As a result, it has become possible to apply this method to plain paper copying systems, which have the drawbacks of toners in which colorants are fixed on the surface of thermoplastic resin particles.

(Example) The present invention will be explained below with reference to Examples. In the examples, "part" means part by weight, and "%" means % by weight.

Example 1 100 parts of spherical styrene-acrylic resin fine particles (average particle size 9.6 μ'') produced by suspension polymerization, Pigment Blank 27 (trade name: Diviroxide Blasoku 95)
80. Manufactured by Dainichiseika Kagyo Co., Ltd., 10 parts of oxidized compound of Fe and Cr (with volume resistivity 1XlO7Ω), charge control agent (trade name: PNP-BE, Orient Chemical Co., Ltd.)
150 g of a mixture of 1.0 part (manufactured by Co., Ltd.) was introduced into a test medium stirring mill having a capacity of 1.2β and having a rod-shaped stirring blade. As the spherical medium, 1 kg of 3/16 inch chrome steel balls are used.
The stirring blade was rotated at 50 rpm for 15 minutes. 'In addition, water is used as a dispersion aid at 1% of the toner raw material.
and the vessel was water cooled by a jacket. The toner particles thus obtained had an average particle size of 10.4μ and 2
The concentration of Oμ or more was 2.5%, and there was no problem with aggregation. Visual observation using an electron microscope shows that the dispersion medium is deformed somewhat irregularly due to the impact force, but it is generally spherical, and the optical w
Visual observation using a 4-microscope revealed uniform coloring, with no uncolored particles or free pigment present. In addition, this toner was pressurized at 400 kg/ci, and the diameter was 2 cm and the thickness was about 2 cm.
When measuring the volume resistivity using a guard electrode with a mm pellet and an applied voltage of 100V, it was 9 x 106Ωc.
It was m.

Next, 98 parts of commercially available carrier particles (product name: TY-100 manufactured by Kanto Denka Kogyo C Co., Ltd.) were added to 2 parts of the above toner particles, and after thorough stirring, a blow-off charge amount measuring device (product name: Toshiba Chemical Co., Ltd.) was added. When the amount of charge was measured using a product manufactured by ), it was found to be well charged at -16.5 μC/g. In addition, for 100 parts of the above toner, colloidal silica (product name R
-972, manufactured by Nippon Aerosil Co., Ltd.) was added to a commercially available copying machine (trade name: Rheodory 4140, manufactured by Nippon Aerosil Co., Ltd.).
When we conducted a printing test on Toshiba (manufactured by Toshiba), it was found that
℃ and 80% RH), good images could be obtained.

Note that the volume resistivity value of the black oxide fine particles was determined by the following measurement method since a molded product could not be obtained by the above method. Electrometer/Source Type 617 (KEITH
LE), a powder electrode P-616, and a shield box (all newly manufactured by Kawaguchi Denki Seisakusho). Apply 100V to the above powder electrode, which consists of a main electrode with a diameter of 5 cm + and a guard electrode on the outside. Apply voltage and measure and calculate the volume resistivity value.

Example 2 Styrene-acrylic resin (trade name: xP^-3336, manufactured by Mitsui Toatsu Chemical Co., Ltd.) produced by solution polymerization was pulverized using a jet mill to obtain fine resin particles with an average particle size of 9.7μ. Manufactured. To 100 parts of these particles, 12 parts of the dipyroxide blank used in Example 1 and 1.0 parts of the charge control agent.
0 parts 150 g of mixture 1 part 8 inch chrome steel ball 1
kg, and treated in the same manner as in Example 1.

The toner particles thus obtained had an average particle diameter I of 0.5 μm, but the proportion of coarse particles of 20 parts or more was 4.5% or less, and no coarse agglomerated particles were observed when observed using an electron microscope. Furthermore, observation using an optical microscope revealed that the surface was uniformly colored with black metal oxide fine particles.

Further, when the volume resistivity of this toner was measured in the same manner as in Example 1, it was found to be 9X10'''Ω value, and the charge amount was also good at -15°3 μC/g. We conducted a test and obtained good results.

Example 3 100 parts of spherical styrene-acrylic resin fine particles (average particle size 9.6μ) produced by suspension polymerization, Pigment Black 28 (C, 1,77428, volume resistivity l)
A trial production was conducted in the same manner as in Example 1 using a mixture of 1.0 part of Xl0'Ωell) and 1.0 part of the charge control agent used in Example 1. The obtained particles have a charge amount of -20.7μC
/g, and the volume resistivity is lXl0"
As a result of conducting the same printing test as in Example 1, a good image was obtained.

Example 4 In Example 2, titanium black (volume resistivity 6XIO'Ωc) was used instead of 10 parts of dipyroxide black.
When a similar test was conducted using 15 parts of m+), similarly good results were obtained.

Comparative Example 1 A toner was produced using 3 parts of carbon blank (trade name #44, manufactured by Mitsubishi Chemical Industries, Ltd.) in place of 10 parts of dipyroxide black used in Example 1. The volume resistivity of this toner was 1×1O12Ω. When this toner was subjected to the same printing test as in Example 1, the transfer to plain paper was poor and sufficient image density could not be obtained. Comparative Example 2 A toner was produced using iron black (triiron tetroxide) (trade name: BL-100°, manufactured by Titan Industries Co., Ltd.) in place of the dipyroxide black used in Example 1. The volume resistivity of this toner was 6 x 10''Ω. When this toner was subjected to the same printing test as in Example 1, sufficient image density could not be obtained due to insufficient transfer to plain paper.

Claims (1)

[Claims] 1. On the surface of thermoplastic resin particles with an average particle size of 1 to 15 μm, particles with a particle size of 0.5 μm or less and a volume resistivity of 5 × 1
The above-mentioned toner for developing an electrostatic image, characterized in that a black nonferrous metal oxide or an iron/nonferrous metal mixed oxide having a resistance of 0^6 Ωcm or more is fixed alone or together with a charge control agent and other necessary fine particles.