JPH0337183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry two-component developer used for developing electrostatic latent images, and in particular to a developer that can provide stable images even against environmental changes such as humidity. .

The conventionally used developers for electrostatic latent images are:
Generally, when humidity increases, the amount of toner charge decreases, resulting in a decrease in resolution, background smearing, and a significant increase in image density, which impairs image quality. Therefore, in order to prevent such a decrease in charge amount during high humidity, additives such as cerium oxide, chromium oxide, aluminum oxide, magnesium oxide, silicon oxide, tin oxide, zirconium oxide, iron oxide, and titanium oxide were used as additives. oxides such as; sulfates such as calcium sulfate, barium sulfate, aluminum sulfate; silicates such as calcium silicate and magnesium silicate; titanides such as boron titanide and titanium titanide; silicon carbide, titanium carbide, boron carbide, Carbides such as tungsten carbide and zirconium carbide;
Do not use hygroscopic substances such as borides such as zirconium boride, titanium boride, etc., and
As toner materials and carrier coating materials, attempts have been made to use resins with as low hygroscopicity as possible, rather than using highly hygroscopic resins such as unsaturated polyester. However, even after examining various materials in this way, the amount of charge under high humidity conditions is about 30 to 40% lower than that under low humidity conditions, and rapid humidity fluctuations occur in the environment in which the copying machine is used. The image quality varied greatly. Images fluctuate depending on the season, making it impossible to obtain stable image quality and not achieving satisfactory results.

Therefore, it is an object of the present invention to provide a developer for electrostatic latent images that solves the above-mentioned conventional drawbacks, and more specifically, it is an object of the present invention to provide a developer for electrostatic latent images that eliminates changes in the amount of negative charge of toner due to changes in humidity. The purpose of this invention is to provide a developer that can always form stable images.

After various studies in view of the purpose of the present invention, it was found that all of the above-mentioned drawbacks can be overcome by incorporating a specific metal complex dye into the toner and using a carrier coated with styrene or acrylic resin. This finding led to the present invention.

That is, the present invention provides an electrostatic latent image developer comprising a toner and a carrier, which has the general formula (However, X, Y, Z are hydrogen, halogen, carboxyl group, hydroxyl group, nitro group, sulfo group,
represents a sulfamide group, and A ⁺ is H ⁺ , K ⁺ ,
Represents Na ⁺ or an aliphatic ammonium cation. ) is contained in the toner, and a carrier coated with a resin obtained by polymerizing at least one monomer selected from styrene monomers and acrylic monomers is used. This is a developer for electrostatic latent images.

The resin used for toner in the present invention includes polystyrene, chloropolystyrene polymer, styrene-propylene copolymer, styrene-propylene copolymer, and styrene-propylene copolymer.
Butadiene copolymer, styrene-vinyl chloride copolymer, styrene-acrylic acid ester copolymer,
Examples include hydrophobic resins such as styrene-methacrylate copolymer, acrylic resin, vinyl chloride resin, epoxy resin, polyurethane resin, xylene resin, and polyvinyl brachyl. The toner particles of the present invention are structured according to conventionally known methods, including, for example, the above-mentioned resin components, a metal complex dye, and a compound ordinarily, but not necessarily, used for forming a visible image. It is obtained by thoroughly mixing a coloring agent such as carbon black, kneading it in a hot roll mill, cooling it, solidifying it, crushing it and classifying it.

The carrier coating resin is a resin obtained by polymerizing at least one monomer selected from styrene monomers and acrylic monomers, and the vinyl monomers include styrene, α-
Methyl styrene, P-chlorostyrene, P-methylstyrene, acrylic monomers include methyl acrylate, methyl methacrylate butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, dodecyl acrylate, lauryl methacrylate, cyclohexyl acrylate, Examples include acrylic acid and methacrylic acid ester monomers such as dimethylaminoethyl acrylate, diethylaminomethyl methacrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl methacrylate.

The amount of toner used is preferably mixed so that toner particles adhere to the carrier surface and occupy 30 to 90% of the carrier surface area.

By having the above configuration, the present invention has the following features:
It was possible to prevent a decrease in image quality, especially an increase in image density, due to a decrease in the amount of charge during high humidity, and it was possible to obtain a stable image that is unaffected by environmental changes.

Hereinafter, the present invention will be explained in more detail by giving examples.

Example 1 A negatively charged toner having an average particle size of 8 μm was prepared using a metal complex dye having the following structural formula (1) according to the following formulation.

Prescription styrene resin (Hercules D-125)
85 parts by weight Metal complex dye (structural formula (1)) 2 parts by weight Carbon black 13 parts by weight On the other hand, 40 g of methyl methacrylate resin (Mitsubishi Rayon Co., Ltd. BR85) was coated on the surface of 5 kg of iron oxide powder with a diameter of 100 μm using a fluidized bed coating device to obtain a resin-coated carrier.

Toner was mixed with the carrier at a ratio of 2.0 wt% to prepare a developer. Then 10℃, 30%
The developer was spread thinly under the conditions of 90% and 30° C., and the humidity was controlled for 5 hours, followed by image formation under these conditions using a copying machine FT6600 manufactured by Ricoh.

As a result, as shown in FIG. 1, there was almost no variation in image density due to environmental changes, and as for variation in charge amount, there was no decrease at all under high humidity as shown in FIG.

Example 2 A negatively charged toner having an average particle size of 8 μm was prepared using a metal complex dye having the following structural formula (2) according to the following recipe.

Formula Styrene resin 84 parts by weight Metal complex dye (structural formula (2)) 2 parts by weight Carbon black 14 parts by weight On the other hand, 40 g of methyl methacrylate resin (Mitsubishi Rayon Co., Ltd. BR85) was coated on the surface of 5 kg of iron oxide powder with a diameter of 100 μm using a fluidized bed coating device to obtain a resin-coated carrier.

Toner was mixed with the carrier at a ratio of 2.0 wt% to prepare a developer. Then 10℃, 30%
The developer was spread thinly under the conditions of 90% and 30° C., and the humidity was controlled for 5 hours, followed by image formation under these conditions using a copying machine FT6600 manufactured by Ricoh.

As a result, as shown in FIG. 3, there was almost no variation in image density due to environmental changes, and there were no other changes in image quality. Regarding the variation in the amount of charge, as shown in FIG. 4, there was almost no decrease at high humidity.

Example 3 Using metal complex dye 3 having the following structure,
A negatively charged toner with an average particle size of 8μ was prepared using the following recipe.

Prescription Styrene-n-butyl methacrylate copolymer resin (SBM600 manufactured by Sanyo Chemical Co., Ltd.) 90 parts by weight Metal complex dye (structural formula (3)) 1 part by weight Carbon black 9 parts by weight On the other hand, styrene resin (Hercules D-125)
50 g of the powder was coated on the surface of 5 kg of iron oxide powder with a diameter of 100 μm using a fluidized bed coating device to obtain a resin carrier.

Toner was mixed with the carrier at a ratio of 2.0 wt% to prepare a developer. Then 10℃, 30%
The developer was spread thinly under the conditions of 90% and 30° C., and the humidity was controlled for 5 hours, followed by image formation under these conditions using a copying machine FT6600 manufactured by Ricoh.

As a result, as in Examples 1 and 2, almost no change in image density or charge amount was observed.

Example 4 Instead of methyl methacrylate, styrene-
Butyl methacrylate resin (manufactured by Sanyo Chemical Co., Ltd.)
A carrier, toner, and developer were prepared in exactly the same manner as in Example 1, except that SBM700) was used. After that, the developer was spread thinly in environments of 10℃, 30% and 30℃, 90%, and after conditioning the humidity for 5 hours, using a Ricoh copier FT6600,
Images were taken under these conditions.

As a result, the image density was 1.25 for low humidity and 1.27 for high humidity.
And the amount of charge at that time is −
There was almost no change at 17.9μc/g and -17.2μc/g for high humidity.

Comparative example 1 A toner with an average particle size of 8μ was prepared using the following recipe.

Prescription Styrene 85 parts by weight Carbon black 15 parts by weight Meanwhile, 40 g of methyl methacrylate resin (Mitsubishi Rayon Co., Ltd. BR85) was coated on the surface of 5 kg of iron oxide powder with a diameter of 100 μ using a fluidized bed coating device. A coated carrier was obtained.

Toner was mixed with the carrier at a ratio of 1.50 wt% to prepare a developer. Then 10℃, 30%
The developer was spread thinly under the conditions of 90% and 30° C., and the humidity was controlled for 5 hours, followed by image formation under these conditions using a copying machine FT6600 manufactured by Ricoh.

As a result, the image density fluctuations are as shown in Figure 5.
There is a significant difference between 0.9 for low quality and 1.35 for high humidity.
In high humidity conditions, the resolution deteriorated due to too much toner adhesion, and background smudges also increased.
In addition, when we investigated the variation in the amount of toner charge, we found that
As shown in the figure, it is -14μc/g at low humidity, while
At high humidity, it was as low as -8 μc/g.

Comparative Example 2 The following structural formula, A toner having an average particle size of 8 μm was prepared using an azo complex dye having the following formula.

Prescription Styrene resin (D125 manufactured by Harleskiu)
85 parts by weight of the above azo complex dye 2 parts by weight Carbon black 13 parts by weight Methyl methacrylate resin (Mitsubishi Rayon)
BR85) was coated on the surface of 5 kg of iron oxide powder with a diameter of 100 μm using a fluidized bed coating device to obtain a resin-coated carrier.

Toner was mixed with the carrier at a ratio of 2.0 wt% to prepare a developer. The amount of charge of the obtained developer was -11.2 μc/g.

After that, the developer was spread thinly in the environments of 10℃, 30% and 30℃, 90%, and the humidity was adjusted for 5 hours. I created an image.

As a result, the image density was 1.23 for low humidity, and 1.23 for high humidity.
It was 1.38. In addition, in a high humidity environment, there was severe background smearing and toner scattering. When we investigated the amount of charge, it was -14.6μc/g in low humidity and -8.2μc/g in high humidity.
It was hot.

[Brief explanation of the drawing]

Figures 1 to 4 show image density fluctuations and charge amount fluctuations due to environmental changes in the developer of the present invention, and Figures 5 and 6 show image density fluctuations and charge amount fluctuations due to environmental changes in the developer of the comparative example. It is a graph showing quantity fluctuation.

Claims (1)

[Scope of Claims] 1. In an electrostatic latent image developer comprising a toner and a carrier, the general formula (However, X, Y, and Z represent hydrogen, halogen, carboxyl group, hydroxyl group, nitro group, sulfone group, and sulfamide group, and A ⁺ represents H ⁺ ,
Represents K ⁺ , Na ⁺ or an aliphatic ammonium cation. ) is contained in the toner, and the carrier is coated with a resin obtained by polymerizing at least one monomer selected from styrene monomers and acrylic monomers. A developer for electrostatic latent images.