JP3148951B2 - Color toner and image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color toner for electrophotography and a method for forming a multicolor image, and more particularly to a method for forming a batch transfer image.

[0002]

2. Description of the Related Art As a multicolor image forming method, a single toner image layer is formed on a latent image forming body by contact development, and is transferred onto a transfer material each time, and this process is repeated a plurality of times. A multi-toner image layer is formed by accumulating a toner image layer on a latent image forming body by non-contact development in accordance with the formation of an electrostatic latent image, and the multi-toner image layer is directly transferred onto a transfer material at a time. Although the transfer method is known, the advantage of the batch transfer method is great because the apparatus can be downsized and there is no color shift.

In addition, in the case of a transfer drum system, in the formation of a color image having many solid images, the cleaning step of the latent image forming body surface is required a plurality of times for one multicolor image. In particular, under severe conditions such as high temperature and high humidity, cleaning failure is likely to occur. In this regard, the batch transfer method requires only one cleaning step for one image even for a multicolor image, which is also advantageous in this respect.

However, this batch transfer system has the following disadvantages. That is, in non-contact development, since the physical adhesion between the toner and the carrier or the toner conveying member is more greatly affected, an external additive that is present around the toner for the purpose of reducing the physical adhesion is used. However, those conventionally used as external additives have a relatively small particle size, and the external additives are easily buried in the toner surface due to stress received in a developing device or the like,
Developability is likely to be reduced due to an increase in physical adhesion.

Some external additives which have relatively large particle diameters and are hardly buried in the toner surface are known. However, the conventional external additives have a low adhering ability to the toner and exist in a free state. , The effect of reducing the physical adhesion was poor.

As described above, the batch transfer method has a great merit, but at the present time, the merit cannot be fully utilized due to the above-mentioned drawbacks.

[0007]

OBJECTS OF THE INVENTION The objects of the present invention are: 1. Stabilization of developability, especially non-contact developability To provide a multi-color image forming system that satisfies the conditions for improved cleaning
Further 3. The purpose is to downsize and simplify the image forming apparatus.

[0008]

The purpose of the present invention DETAILED DESCRIPTION OF THE INVENTION: In the toner containing the resin fine particles having an average particle diameter D of entailment the small of Kutomo colorants [μm], and an inorganic fine particles having an average particle diameter of 50 to 120 nm, When the amount ratio of the inorganic fine particles to the resin fine particles is m [vol%], the relationship between the charge amount A of the toner when the inorganic fine particles are not added and the charge amount B when the inorganic fine particles are added is: 0 ≦ (BA) / (m ^2/3 ) ≦ 15.0 (1), and the ratio of the inorganic fine particles to the resin fine particles
m [vol%] is 5.0 / D ≦ m ≦ 15.0 / D (2), and a two-component developer containing the color toner and a carrier is used. An image forming method in which a multi-toner image layer is formed on an image forming body, and the multi-toner image layer is directly transferred collectively.

In the present invention, in order to greatly reduce the physical adhesion due to the effect of the addition of the external additive, as a criterion for adjusting the characteristics, the charge amount is determined based on the resin fineness in the toner.
The difference between the value A of the toner when the external additive is not added and the value B when the external additive is added of the charge amount Q / M of the toner is obtained by balancing the amount ratio m [vol%] of the external additive with respect to the particles. According to (1), and with respect to the coating effect of the external additive and the burial resistance, the amount ratio m [vol%] of the external additive to the resin fine particles in the toner is determined according to the above-mentioned relational expression (2) and further to the relational expression An external additive having a large particle size of 50 to 120 nm is used in order to satisfy (1) and (2) without any problem.

If the ratio (BA) is too large, the adhesive force between the carrier and the external additive increases and the developing property decreases. If the ratio (BA) is too small, the electrostatic adhesive force decreases and the toner adheres to the toner surface. Poor coverage. Further , the amount ratio of the external additive to the resin fine particles m
Is less than 5.0 / D, the coating is insufficient and the effect is not sufficient.
If it exceeds 15.0 / D, internal contamination due to free external additives occurs.

When the particle size of the external additive exceeds 120 nm, the fluidity is impaired and the developing property is reduced.

Next, the binder resin used in the toner according to the present invention is not particularly limited, and various resins can be used. ^{2 × 10 4 ~3 ×; M} W is the average molecular weight
10 ⁵ , M _N ; 5 × 10 ^{3 to} 1.5 × 10 ⁴ , T _g ; 50 to 65 ° C. are preferred.

Specifically, for example, styrene resins, acrylic resins, styrene / acrylic copolymer resins, epoxy resins, polyester resins and the like can be mentioned.
Further, those having a side chain are preferable, and burying of the external additive can be more effectively suppressed by its buffering property. These resins may be used in combination.

The styrene-acrylic copolymer resin as the binder resin is a resin composed of a copolymer of a styrene monomer and an acrylic monomer.

The polyester resin as the binder resin is obtained by polycondensation of a polyhydric alcohol monomer and a polycarboxylic acid monomer.

Various additives are used as additives contained in the toner.

Various colorants such as carbon black, azo type, diazo type, quinacridone type, perylene type, phthalocyanine type, triarylamine type and rhodamine type are used as the colorant for the internal additive of the toner according to the present invention. be able to. Specific examples include the following.

(Black pigment): carbon black, nigrosine (magenta pigment or red pigment): CI Pigment Red 5 CI Pigment Red 48: 1 CI Pigment Red 53: 1 CI Pigment Red 57: 1 CI Pigment Red 122 CI Pigment Red 123 CI Pigment Red 139 CI Pigment Red 144 CI Pigment Red 149 CI Pigment Red 166 CI Pigment Red 177 CI Pigment Red 178 CI Pigment Red 222 (Orange Pigment or Yellow Pigment): CI Pigment Orange 31 CI Pigment Orange 43 CI Pigment Yellow 17 CI Pigment Yellow 14 CI Pigment Yellow 138 CI Pigment Yellow 93 CI Pigment Yellow 94 CI Pigment Yellow 174 (Green Pigment or Cyan Pigment): CI Pigment Green 7 CI Pigment Blue 15 CI Pigment Blue 15: 2 CI Pigment Instruments Blue 15: 3 content of CI Pigment Blue 60 or more colorants is preferably 0.5 to 15% of the toner.

[0019] Other optional toner additives that may be used include, for example, a charge control agent and a fixability improving agent (release agent).

As the charge control agent, for example, nigrosine dyes, metal complex dyes, ammonium salt compounds, aminotriphenylmethane dyes and the like can be used.

The charge control agent is contained in an amount of 0 to 5% by weight based on the weight of the binder resin of the toner.

In the case of a color toner, a colorless or white color toner is preferable in order not to impair the coloring properties of the color toner.

Examples of the fixability improver (release agent) include low molecular weight polyolefins such as low molecular weight polypropylene, low molecular weight polyethylene, and low molecular weight polybutene.
Fatty acid esters such as ethyl maleate, butyl maleate, methyl stearate, butyl stearate, cetyl palmitate, ethylene glycol montanate, and partially saponified products thereof, natural paraffin, micro wax, synthetic paraffin, etc. Paraffin wax, amide wax such as stearamide, olefin amide, palmitic amide, lauric amide, behenic amide, methylene bis-stearamide, ethylene bis-stearamide, and carnauba wax can be used. .

A preferable content ratio is 1 to toner.
~ 6 wt%.

In the present invention, in order to improve the characteristics of the toner as an external additive, inorganic fine particles are further added to and mixed with the toner described above.

Examples of such inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, antimony trioxide, zirconium oxide, and carbon dioxide. Fine particles of silicon or the like can be given. Particularly, silica fine particles and titanium oxide fine particles are preferable.

It is preferable to use hydrophobic particles of these inorganic particles.

The hydrophobizing treatment is carried out, for example, by mixing the fluidizing agent fine particles as described above with a silane coupling agent such as dialkyldihalogenated silane, trialkylhalogenated silane, alkyltrihalogenated silane, hexaalkyldisilazane or dimethyl coupling agent. The reaction can be carried out by reacting with a hydrophobizing agent such as silicone oil such as silicone oil at a high temperature.

Further, in order to improve the cleaning property of the cleaning method using a blade, a fatty acid metal salt such as zinc stearate may be added and mixed at a ratio of 0.01 to 50% by weight based on the weight of the developer.

In the present invention, when a two-component developer is prepared, a carrier is further used together with the toner and the inorganic fine particles.

The carrier is not particularly limited, but may be an uncoated carrier made of magnetic particles, a resin-coated carrier obtained by coating the surface of magnetic particles with a resin, or a magnetic material dispersed and contained in a binder resin. Magnetic material-dispersed carrier or the like can be used.

The magnetic particles constituting the carrier include:
A substance that is strongly magnetized in that direction by a magnetic field, for example, iron,
Ferromagnetic metals or alloys such as ferrite, magnetite, nickel, and cobalt, or compounds containing these elements, or alloys that do not contain ferromagnetic elements but become ferromagnetic by appropriate heat treatment For example, an alloy of a kind called a Heusler alloy such as manganese-copper-aluminum or manganese-copper-tin, or particles made of chromium dioxide or the like can be used.

Here, ferrite is a general term for magnetic oxides containing iron, and is not limited to spinel-type ferrite represented by the chemical formula of MO.Fe ₂ O ₃ (M is a divalent metal). Such ferrite can be suitably used in the present invention because various magnetic properties can be obtained by changing the composition of the contained metal component. Among them, a copper-zinc ferrite is particularly preferable because it has a higher electric resistance than a manganese-zinc ferrite and a nickel-zinc ferrite, and exhibits excellent triboelectric charging ability. Also, since ferrite is an oxide, its specific gravity is smaller and lighter than metals such as iron and nickel. Therefore, it is easy to mix and stir with toner, uniform toner concentration, and uniform triboelectric charge. It is suitable in achieving.

As the coating resin for the resin-coated carrier or the binder resin for the magnetic material-dispersed carrier, for example, a styrene-acrylic copolymer, a silicone compound, a fluorine resin, or the like can be suitably used.

The average particle size of the carrier is preferably from 20 to 100 μm, and particularly preferably from 30 to 55 μm in the batch transfer method. When the average particle size is too small, a so-called carrier adhesion phenomenon in which the carrier adheres to the electrostatic latent image occurs, and as a result, the image may be unclear. On the other hand, when the average particle size is too large, image deletion may occur. is there.

The saturation magnetization is preferably 15 to 35 emu / g.

[0037]

Next, the present invention will be described in detail with reference to examples.

The materials used in the examples and comparative examples are shown in Tables 1 and 2 below.

The base toner BT of Table 1 was finished to 8 μm,
Inorganic fine particles T1-8 and H having the specifications and characteristics of Table 2
1 to 8 were mixed using a Henschel mixer.

Next, a carrier obtained by coating a ferrite particle having a saturation magnetization of 22 emu / g and an average particle diameter of 40 μm with a copolymer having a composition of MMA / st = 6/4 by 2 wt%, and a toner / carrier ratio of 7 wt%
% To prepare a developer using each toner.

[0041]

[Table 1]

[0042]

[Table 2]

Evaluation of properties Evaluation machine: (1) Konica 9028 was used (FIG. 1 (1)).

Reference numeral 9028 is provided with an opc photoreceptor and a blade cleaning device. In the multi-color mode, non-contact development is repeated several times to form a multi-color image on the drum, and then transfer the image in batch. Table 3 shows the results.

(2) A modified Konica 9028 was used (FIG. 1).
(2)).

A transfer drum is mounted on Konica 9028, and transfer is performed each time one-color contact development is performed, and cleaning is performed by a blade cleaning device. Table 4 shows the results.

The evaluation was performed using the developing property, cleaning property and transfer property as scales.

Developability: A patch of 2 cm × 5 cm was developed at 30,000 copies, and the amount of developed toner per 1 cm ² on the photoreceptor was calculated by measurement, and judged by the change width from the initial stage.

Cleaning performance: Judgment was made based on the timing of occurrence of cleaning failure when copying 30,000 sheets.

Transferability: Determined by the ratio of the toner on the transfer paper to the total development amount in the same manner as in the measurement of the developability.

[0051]

[Table 3]

[0052]

[Table 4]

[0053]

According to the constitution of the present invention, the stability of the developing property, the uniform attachment of the external additive and the improvement of the durability can be attained, and the apparatus can be reduced in size and simplified.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a multicolor image forming apparatus used for evaluation of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st developing device 2 2nd developing device 3 3rd developing device 4 4th developing device 5 Photoconductor drum 6 Transfer pole 7 Cleaning unit 8 Charging unit 9 Feeding unit 10 Transfer drum

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-109571 (JP, A) JP-A-2-83551 (JP, A) JP-A-2-298957 (JP, A) JP-A-59-1984 83171 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (2)

(57) [Claims] 1. A mean particle diameter D of entailment the small of Kutomo colorants
[Μm] resin fine particles and inorganic fine particles having an average particle diameter of 50 to 120 nm, wherein the resin fine particles
When the amount ratio of the inorganic fine particles to the toner is m [vol%], the relationship between the charge amount A of the toner when the inorganic fine particles are not added and the charge amount B when the inorganic fine particles are added is 3.0 ≦ (BA). / (M ^2/3 ) ≦ 15.0, and the amount ratio of the inorganic fine particles to the resin fine particles
m [vol%], wherein 5.0 / D ≦ m ≦ 15.0 / D. 2. A latent image forming member is formed on a latent image forming member by using a two-component developer containing a color toner and a carrier according to claim 1 to form a latent image on the latent image forming member and performing non-contact development. An image forming method in which a multi-toner image layer is formed and the multi-toner image layer is directly and collectively transferred to a transfer material.