JPH0574818B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention applies not only to a two-component developer but also to a two-component developer.
The present invention relates to a toner for developing electrostatic latent images that can be used also as a component-based developer and that has a fluidizing agent added thereto. The above-mentioned fluidizing agent is used to impart fluidity and good chargeability to the toner and to increase transfer efficiency. Conventionally, fine powders such as silica and titanium oxide have been added as a fluidizing agent. It is known to do. However, these fluidizing agents are hydrophilic, and due to their moisture absorption, especially at high humidity, the toner may not have sufficient charge, resulting in poor development efficiency, toner scattering, and image fading. The drawback was that the image density was significantly reduced. Therefore, for example, as shown in JP-A-52-30437, JP-A-51-179861, and JP-A-58-60754, silica is used as a fluidizing agent by using silicone oil or a silane coupling agent. Some toners use hydrophobized toners, but in these cases, the amount of charge on the toner increases or decreases dramatically as it is repeatedly used to develop electrostatic latent images.
There was a drawback that the density of the developed image varied greatly. In view of the above points, the present invention aims to provide a toner for electrostatic latent images that does not cause fluctuations in developed image density even when used repeatedly as well as under high humidity conditions. In order to achieve the above-mentioned object, the toner for developing electrostatic latent images of the present invention includes fluidizing agent particles that have been hydrophobized to have the same polarity as the charge polarity of the toner, and hydrophobization treatment to have the polarity opposite to the charge polarity of the toner. The superplasticizer particles are mixed and added at a weight ratio of 10:1 to 1:5, and the total amount of both superplasticizer particles is 0.05 to 20wt%. do. In other words, using fluidizer particles that have been hydrophobized, and adding fluidizer particles that have the same polarity as the toner's charge polarity and those that have the opposite polarity to the toner's charge polarity, The increase or decrease in the amount of charge during repeated use, which occurs in toners to which simply hydrophobized fluidizing agent particles are added, is offset by the use of fluidizing agent particles with a polarity opposite to that of the toner. It is to prevent it. Therefore, due to its hydrophobicity, the toner does not easily clump even under high humidity conditions, has excellent so-called blocking resistance, has good fluidity, has excellent transferability, and can avoid attenuation of the toner charge amount. Furthermore, even during repeated use, the amount of charge is stable, and the density of the developed image does not vary, making it possible to obtain copies with good image quality. The toner of the present invention is made by dispersing a coloring agent in a thermoplastic resin, and in addition to these, as a charge control agent, a chromium-containing oil-soluble dye, a nigrosine-based oil-soluble dye, etc. may also be used as necessary. It is contained. Thermoplastic resins include polystyrene and polyP.
- Monopolymers of styrene and its substituted products such as chlorostyrene and polyvinyltoluene, styrene-P
-Chlorstyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene- Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl (methacrylate) copolymer,
Styrene-butyl methacrylate copolymer, styrene-d chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-
Styrenic copolymers such as acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene maleate copolymer, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, Polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyamide, polyacrylic acid resin,
Rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. can be used alone or in combination. Further, in order to use the toner of the present invention as a magnetic toner, magnetic powder may be included. Such magnetic powder is a substance that is magnetized when placed in a magnetic field, and includes powders of ferromagnetic metals such as iron, cobalt, and nickel, and alloys and compounds such as magnetite, hematite, and ferrite. The content of this magnetic powder is 15~15% based on the weight of the toner.
Preferably it is 70wt%. As the fluidizing agent mixed and added to the toner of the present invention, silica, alumina, titanium oxide, silica/alumina, etc., which have been subjected to hydrophobic treatment to have positive triboelectric charging property and negative tribocharging property, are used. Examples of toner production, carrier production, synthetic examples of fluidizing agents, examples, and comparative examples will be described below. [Example of toner production] Polyester resin (softening point 120℃, glass transfer
60℃) 100 parts by weight Carbon black (Mitsubishi Chemical Industries, Ltd. MA)
#8) 5 parts by weight After thoroughly mixing the above materials in a ball mill, they were kneaded on a heated three roll roll. After the kneaded material was left to cool, it was coarsely ground using a feather mill, and further finely ground using a jet mill. After that, it is classified and the average particle size is
A toner of 13 μm was obtained. This is hereinafter referred to as toner A. Further, a toner with the same composition ratio using a styrene-acrylic resin (softening point: 120° C., glass transition point: 58° C.) instead of the polyester resin is hereinafter referred to as toner B. Both toners A and B are negatively chargeable toners. [Example of manufacturing carrier] Styrene/acrylic resin (manufactured by Good Year Co., Ltd., Priorite ACL) 100 parts by weight Magnetic powder (manufactured by Titan Kogyo Co., Ltd., Mabiko Black BL)
-500) 200 parts by weight carbon black (Mitsubishi Chemical Corporation MA-
100) 5 parts by weight The above materials were sufficiently mixed and pulverized using a ball mill, and then sufficiently heated using three rolls to melt and knead. The powder was further finely pulverized with a jet mill and then classified to obtain a magnetic carrier with an average particle size of 40 μm and a volume resistivity of 10 ¹⁴ Ω·cm. [Example of synthesis of fluidizing agent] (i) Put 500 ml of special grade methanol in a flask, and add 5 g of aminosilane coupling agent (δ-(2-aminoethyl)aminopropylmethoxysilane): SH6020 (manufactured by Toray Silicon Co., Ltd.). , and stirred thoroughly to completely dissolve. 100 g of Siri Lot. 200 (manufactured by Degussa) was added to this and sufficiently suspended. Thereafter, this reaction solution was heated to 80°C to remove methanol and water produced by the reaction, and the residue was then transferred to a desiccator (desiccant, drying agent, etc.).
It was stored dry in silica gel). The positively triboelectrically charged fluidizing agent particles thus obtained are referred to as (+) silica. (ii) Positive triboelectric fluidizing agent particles were obtained in the same manner as in (i) above, using aluminum oxide C (manufactured by Degussa) in place of the silica Lot. 200. This is called (+) alumina. (iii) A positively triboelectric fluidizing agent was obtained in the same manner as in (i) above, using titanium oxide P-25 (manufactured by Degussa) in place of the silica Lot. 200. This is called (+) titanium. (iv) Silica alumina instead of the above silica Lot.200
A positively triboelectric fluidizing agent was obtained using MOX.80 (manufactured by Degussa) in the same manner as in (i) above. This is called (+) silica alumina. Example 1 To the aforementioned toner A, 0.1 wt% of hydrophobized silica (negatively triboelectrically charged hydrophobized silica treated with dimethyldichlorosilane) R976 (manufactured by Nippon Aerosil Co., Ltd.) and the above (i) were added. (+) Silica
Add 0.05wt% each and use a Henschel mixer.
Mix at 1200 rpm for 3 minutes, add 450 parts by weight of the carrier to 50 parts by weight of the mixture thus obtained,
These were thoroughly mixed to prepare a two-component magnetic developer. Using this developer, a positive electrostatic charge image was developed using a magnetic brush development method using a copying machine equipped with a (+) chargeable Se-based photoreceptor and a Teflon-coated heating fixing roll, and 60,000 sheets were printed. Continuous copying was performed, and changes in toner charge amount and image density were measured. Image density was measured using a reflection densitometer. In addition, the image part potential of the electrostatic latent image is
The 600V non-image area potential is approximately 150V. As a result of the above development experiment, an image with excellent resolution and image quality was obtained at the initial stage, and despite repeated copying, there was almost no change in the amount of charge and the image density did not decrease.
It showed a high value of 1.43. Also, fogging on the base,
No aggregation was observed at all. Example 2 A two-component magnetic developer was prepared for the aforementioned Toner B in the same manner as in Example 1, and a development experiment was conducted in the same manner. As a result, the initial image and 6
All images after 10,000 copies had excellent resolution and image quality, and the amount of charge remained stable regardless of repeated copying. Examples 3 to 14 Two-component magnetic developers were prepared in the same manner as in Example 1 by adding a fluidizing agent to the aforementioned Toner A or Toner B in the proportions shown in the following table (Table-1). ,
A development experiment was also conducted in the same manner. As a result, good results were obtained in both the initial image, the image after 60,000 copies, and the change in charge amount due to repeated copying. For each of the above Examples 1 to 14, the charge amount and image density were measured at the initial stage, after 30,000 copies, and after 60,000 copies, and the results shown in the following table (Table 1) were obtained. .

【table】

[Table] From the above results, the one with the largest change in charge amount regardless of repeated copying of 60,000 sheets (Example
11), it was 0.8 μc/g, and it was clear that the amount of charge was stable. In addition, even in the case where the change in image density was the largest (Example 14),
In addition to being 0.09, it also shows a high value for image density,
It was clear that both resolution and image quality were excellent. Comparative Example 1 A two-component magnetic developer was prepared in the same manner as in Example 1 by adding only 0.1 wt% of negatively triboelectrically charged hydrophobized silica R976 to the aforementioned toner A, and a development experiment was conducted in the same manner. Ivy. As a result, the initial image was good, but as copying was repeated, the amount of charge increased and the image density decreased from 1.42 to 1.28 after about 10,000 copies. Comparative Example 2 A two-component magnetic developer was prepared in the same manner as in Example 1 by adding only 0.1 wt% of (+) silica in Synthesis Example (i) to the above-mentioned toner A, and a development experiment was conducted in the same manner. I went to As a result, the initial image was good, but due to repeated copying, the amount of charge decreased after 5000 sheets were copied, and significant fogging occurred on the base. Comparative Example 3 to Comparative Example 9 A two-component magnetic developer was prepared in the same manner as in Example 1 by adding a fluidizing agent to the aforementioned Toner A or Toner B in the proportions shown in the following table (Table 2). ,
A development experiment was also conducted in the same manner. As a result, with repeated copying, the amount of charge increased or decreased extremely and became unstable, and the image quality was also poor. For each of Comparative Examples 1 to 9 above, the charge amount and image density were measured at the initial stage, after 5,000 copies, and after 10,000 copies.
The results shown in 2) were obtained.

[Table] From the above results, if only a negatively triboelectrically charged fluidizing agent is added, the image density will drop significantly after 10,000 copies have been made due to an increase in the amount of charge. It is obvious and also
If only a positive triboelectric material is added, the amount of charge will be extremely reduced, the image density will change drastically, and toner scattering and fogging will occur on the undercoat. It was at its limit. For reference, the above synthesis examples (i) to (iv) and R976
[(-)・Silica] The charge amount of each fluidizing agent is listed in the following table (Table 3). However, the amount of charge of each fluidizing agent was measured by a blow-off method based on frictional electrification with iron powder.
Regarding the fluidizing agents in Synthesis Examples (i) to (iv), the amount of charge can be proportionally increased or decreased by increasing or decreasing the amount of Aminolan SH6020 added.

[Table] In the above-mentioned negatively chargeable toner, the flow agent particles were hydrophobized to have positive triboelectric chargeability while maintaining the mixed amount of the superplasticizer at approximately 0.3wt%. When the mixing weight ratio of the fluidizing agent particles was changed, when the weight ratio was less than 0.1, the result was no different from the case where only the fluidizing agent particles that had been hydrophobized to have negative triboelectric charging properties were added. On the other hand, if the weight ratio exceeds 5, the result tends to be the same as when only fluidizing agent particles that have been positively triboelectrically charged and hydrophobized are added. 0.1~5, preferably 0.2~
It was clear that the number needed to be 3. Similarly, in the positively chargeable toner, while maintaining the amount of fluidizer added at 0.3 wt%, the flow agent particles that were hydrophobized to have negative triboelectric chargeability were compared to the fluidizer particles that were hydrophobized to have positive triboelectric chargeability. When the mixing weight ratio of the curing agent particles was changed, the same tendency as in the above-mentioned negatively chargeable toner was observed.
It was also clear that it needed to be 0.1-5, preferably 0.2-3. Furthermore, in each of the negatively chargeable toner and the positively chargeable toner, the mixing weight ratio of fluidizer particles hydrophobically treated to have negative triboelectrification and fluidizer particles hydrophobized to be positively triboelectrically charged was set to 1:1. When the total amount of toner added was varied while maintaining the amount of toner at 0.05 wt%, it was found that if it was less than 0.05 wt%, it lacked fluidity, leading to a decrease in image density during repeated copying, and the inability to replenish toner due to blocking. On the other hand, if it exceeds 2.0 wt%, the fluidity increases more than necessary and fog occurs during repeated copying, so it is clear that it is necessary to reduce the content to 0.05 to 2.0 wt%. From the above results, in order to obtain the desired effect for both negatively chargeable toner and positively chargeable toner, it is necessary to use fluidizer particles that have been hydrophobically treated to have the same polarity as the toner charge polarity and charge the toner. The weight ratio of polarity and fluidizing agent particles treated with hydrophobic treatment to have opposite polarity is 10:1.
It is clear that they should be mixed and added so that the ratio is 1:5 and the total amount of both fluidizing agent particles is 0.05 to 20 wt%.

Claims (1)

[Claims] 1 A toner for developing an electrostatic latent image formed by dispersing a coloring agent in a thermoplastic resin, which comprises fluidizing agent particles that have been hydrophobized to have the same polarity as the toner's charging polarity and opposite polarity to the toner's charging polarity. and superplasticizer particles that have been hydrophobized at a weight ratio of 10:1 to 1:5, and the total amount of both superplasticizer particles added is 0.05 to 2.0 wt%.
A toner for developing an electrostatic latent image, characterized in that the toner is mixed and added so as to have the following properties.