JP3148950B2 - Electrostatic charge developing 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 toner development of an electrostatic latent image, and more particularly to a toner used in electrophotography and a multicolor copying method.

[0002]

2. Description of the Related Art Multi-color and full-color images in electrophotography are formed by forming a plurality of toner image layers composed of colored toners as a multi-layer, but a single toner image formed on a latent image forming body (photoreceptor) is conventionally used. There has been a method in which an image layer is once transferred to an intermediate transfer member one by one, and then re-transferred to a transfer material such as paper. Since this method requires an intermediate transfer member, the size of the apparatus is increased, and color shift easily occurs.

In contrast to this method, a required number of color toner image layers are formed on a latent image forming member as a multi-color toner image layer, and are collectively transferred directly to a transfer material such as paper without passing through an intermediate transfer member. Subsequently, a method of batch fixing has been proposed.

However, non-contact development is required so as not to damage the multicolor toner image layer. By making the non-contact development, the effective electric field strength is weakened, the amount of developed toner is reduced, and the density becomes insufficient. To solve this inconvenience, there has been proposed a method in which an alternating electric field is applied to the developing area and a fluidizing agent having an average particle size of 7 to 30 μm is added (Japanese Patent Application Laid-Open No. 62-182775).

[0005] However, initially, the developability is improved and the fluidity is good, but over time, the developability is reduced and the image density is reduced. In, the toner image layer is present on the latent image forming body for a long time, the adhesion phenomenon proceeds between the two, and transfer failure occurs.

For further improvement of fluidity, there is a proposal of adding 0.3 to 1.0 wt% of hydrophobicized silica having a primary particle diameter of 0.005 to 0.2 μm (Japanese Patent Application Laid-Open No. 64-68765). The effect on the characteristics and the correspondence is not clear, and there is no place to contribute to the adjustment of the characteristics.

[0007]

SUMMARY OF THE INVENTION Based on the demand for miniaturization of copiers and the demand for improvement of characteristics, an object of the present invention is to provide a multi-developing-multi-toner image layer collective transfer system which does not cause color misregistration and apparatus miniaturization. Another object of the present invention is to provide a toner for electrostatic charge development and an image forming method which enable long-term stabilization of image density and transferability and suppression of contamination.

[0008]

The object of the present invention is to provide: a resin fine particle having an average particle diameter [μm] D containing at least a colorant;
An inorganic fine particle having a particle size of up to 120 nm, and the amount ratio [vol%] x of the inorganic fine particle to the resin fine particle is 5.0 / D ≦ x ≦ 15.0 / D. Forming a multi-toner image layer on the latent image forming body by a multi-developing process in which non-contact development is repeatedly performed on the latent image formed on the latent image forming body by using a two-component developer containing the multi-toner image and the carrier; This is achieved by an image forming method in which the layers are directly transferred onto a transfer material at once.

In the toner development using a two-component developer, in the contact type, since the toner surface is in contact with both the drum and the carrier, there is no need to consider the contact situation involving van der Waals force in the development. Then it becomes a problem. On the other hand, the mutual force involved in the contact is proportional to the contact area, and decreases as the contact surface with the carrier decreases and as the distance from the carrier increases.

Therefore, in order to keep the mutual force large, a large particle size external additive is added in the present invention.

Although a sufficient image density can be obtained over a long period of time by improving the developability and preventing the external additive from being buried over time by the mediating effect of the added external additive having a large particle diameter, the toner has a particle diameter of 50 nm. Below this effect is not fully exhibited, 120n
If it is more than m, the adhesiveness to the toner is deteriorated, the external additives are released, and the inside of the device is contaminated. Also, sufficient fluidity cannot be obtained.
On the other hand, the effect varies greatly depending on how much the toner surface is covered. With an addition amount of 5.0 / D ≧ x [vol%], the toner surface coating is insufficient and sufficient effect cannot be obtained, and 15.0 / D ≦
At x [vol%], the coating is excessive, and the inside of the machine due to the release of external additives is caused.

Next, the binder resin used in the toner according to the present invention is not particularly limited, and various resins can be used.

Specifically, for example, styrene resin, acrylic resin, styrene / acrylic copolymer resin, epoxy resin, polyester resin and the like can be mentioned. In particular, side chains which do not give a three-dimensional network structure are used. It is preferable that the external additive is embedded 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 dyes and pigments can be used as the toner colorant according to the present invention. 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 12 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 Blue 15: 3 CI Pigment Blue 60 The content ratio of the colorant above is preferably 0.5 to 15% by weight based on the toner.

Other toner components used as needed include, for example, a charge control agent and a fixability improver (release agent).
And the like.

As the charge control agent, for example, a nigrosine dye, a metal complex dye, an ammonium salt compound, an aminotriphenylmethane dye or 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%.

Further, in order to improve the fluidity of the toner, inorganic fine particles may be further added to and mixed with the toner.

Examples of the 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 zirconium oxide. Fine particles of silicon or the like can be given. Particularly, silica fine particles and titanium oxide fine particles are preferable.

The addition ratio of the inorganic fine particles is 0.05 to 1 w
t% is preferred.

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, copper-zinc-based ferrite and copper-magnesium-based ferrite are particularly preferable, since they have higher electric resistance than manganese-zinc-based ferrite and nickel-zinc-based ferrite and exhibit 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 resin, a fluorine resin, or the like can be suitably used.

The average particle size of the carrier is preferably 20 to 100 μm, particularly preferably 30 to 80 μm. When the average particle diameter is too small, the carrier adheres to the electrostatic latent image and a so-called carrier adhesion phenomenon that forms a fixed image occurs, and as a result, the image may be unclear. That may occur.

[0036]

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

Various materials used in the examples and comparative examples are as follows.

(Binder) Binder 1; polyester resin containing BPA-PO *, BPA-EO **, terephthalic acid, n-dodecenyl succinic anhydride and trimellitic acid as monomer components (Tg = 64 ° C., Tsp = 140 ° C.) Binder 2; polyester resin containing BPA-PO, BPA-EO, terephthalic acid and trimellitic acid as monomer components (Tg = 6)
5 ° C, Tsp = 135 ° C) Binder 3; styrene acrylic resin containing styrene, methyl methacrylate, and butyl acrylate as monomer components (Tg = 55 ° C, Tsp = 110 ° C) * BPA-PO: bisphenol A propylene oxide ** BPA- EO: Bisphenol A ethylene oxide (pigment) Yellow; CI Pigment Yellow 174 Magenta; CI Pigment Red 122 Cyan; CI Pigment Blue 15: 3 Black; Carbon Black (External additive) External additive A; External additive B: hydrophobicized silica having a particle diameter of 40 nm External additive C: hydrophobicized silica having a particle diameter of 35 nm External additive D: hydrophobicized silica having a particle diameter of 50 nm External additive E: hydrophobicized titanium having a particle diameter of 150 nm Agent F: Hydrophobized titanium with a particle size of 120 nm (Method for measuring particle size) Observe a 1.0 μm visual field with a transmission electron microscope, calculate the projected area and number of 100 or more particles, and calculate assuming a sphere The values obtained were used.

(Release Agent) Release Agent A; Polypropylene Release Agent B; Fatty Acid Amide (Charge Control Agent) Charge Control Agent A; Zinc Salt of Salicylic Acid Derivative (Carrier) Average Particle Size 48 μm, σ ₁₀₀₀ = 20 emu / g Cu-
Example 1 Carrier obtained by coating styrene-acrylic resin on Mg-based low-magnetization spherical ferrite Example 1 100 parts of binder 1, 4 parts of yellow pigment and 2 parts of release agents A and B were melt-kneaded and pulverized. Fine particles of 15 μm, 0.33 of external additive A and 0.10 [vol.
%] To give a yellow toner. Similarly, 4 parts of magenta and cyan were added and 10 parts of black were added to obtain toner of each color.

Examples 2 to 16 and Comparative Examples (1) to (16) As shown in Tables 1 and 2 below, the external additives were changed in the same manner as in Example 1 except that the kind of the external additive and the amount of addition were changed. Each color toner was obtained. Note that the external additive C was externally added in an amount of 0.10 [vol%]. In the case of the toner using the binder 3, the charge control agent A was added in 3 parts for each color without adding the release agent at the time of kneading.

[0041]

[Table 1]

[0042]

[Table 2]

[Evaluation Method and Evaluation Results] DC-902 was evaluated.
8 (manufactured by Konica Corp.), and judgment was made based on the density change of the initial image and the image after 20,000 sheets of images were printed, and the state of contamination in the machine.

The evaluation results are shown in Tables 3 and 4.

[0045]

[Table 3]

[0046]

[Table 4]

The image density was measured by Macbeth RD914. Contamination was indicated by the number of sheets at which uneven cleaning due to poor cleaning or contamination of the charged wire began to occur.

[0048]

According to the structure of the present invention, the image density is stable for a long time and no contamination occurs.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-191363 (JP, A) JP-A-4-21861 (JP, A) JP-A 1-273056 (JP, A) JP-A-60-1985 263956 (JP, A) JP-A-60-243665 (JP, A) JP-A-60-243666 (JP, A) JP-A-2-284150 (JP, A) (58) Fields investigated (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, and the ratio x [vol%] of the inorganic fine particles to the resin fine particles is 5.0 / D ≦ x ≦ 15.0 / D The electrostatic charge developing toner. 2. A latent image formed by a two-component developer comprising a toner for electrostatic charge development and a carrier according to claim 1 , wherein the latent image formed on the latent image forming body is repeatedly subjected to non-contact development. An image forming method in which a multi-toner image layer is formed on a body, and the multi-toner image layer is directly transferred collectively to a transfer material.