JPH0424652A - Negatively electrostatically charged cyan toner for color electrophotography - Google Patents

Abstract

PURPOSE:To obtain an excellent electrostatically charging characteristic, aging degradation resistance and moisture resistance by using a phtalocyanine series blue organic pigment whose surface is covered with a negatively electrostatically charged hydrophobic silica as a coloring agent. CONSTITUTION:The surface of the phtalocyanine series blue organic pigment is covered with the negatively electrostatically charged hydrophobic silica. By covering the surface of the pigment with the negatively electrostatically charged hydrophobic silica, a positive charge for which the pigment itself has, is neutralized or the pigment is electrostatically charged at a negative side. Then the polarity of the toner is coincided with that of the pigment and the occurrence of the opposite electrostatically charged toner is prevented. Also since the silica has a hydrophobic property, the improved moisture resistance is provided in a high humidity condition. Thus the negatively electrostatically charged toner with the improved electrostatically charging characteristic, aging degradation resistance and moisture resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a negatively chargeable cyan toner for color electrophotography.

2. Description of the Related Art Toners in which various dyes and pigments are dispersed in a binder resin are widely used as toners for color electrophotography. Among these color toners, those using phthalocyanine organic pigments are mainly used as cyan toners for electrophotography.

This is because phthalocyanine-based organic pigments have a clear blue color and have excellent color reproducibility in both monochrome and multicolor copies. However, since phthalocyanine organic pigments are themselves highly positively chargeable, their use in negatively chargeable toners tends to cause deterioration in copy image quality.

Problems to be Solved by the Invention Phthalocyanine inherently has a tendency to be positively charged, and when used as a negatively chargeable toner, it is recognized that it has a disadvantage in that it tends to economically deteriorate the development characteristics.

Therefore, the present invention eliminates the above-mentioned drawbacks of conventional negatively chargeable cyan toners and provides excellent charging characteristics, resistance to deterioration over time, and moisture resistance.

Means for solving the problems and technical means of the present invention for solving the above problems are as follows:
The surface of a phthalocyanine-based blue organic pigment is coated with negatively charged hydrophobic silica.

The negatively charged hydrophobic silica may be powdered silicon dioxide with a size of 5 to 100 mm and a specific surface area of 80 to 700 m/g. As for this fine powder, Aerosil 130, 2003
00, 380, 0x50. TT600,
MOx80゜MOx170, C0K84R9
72, R812 (manufactured by Nippon Aerosil ■).

C. I. Pigments belonging to Pigment Blue 15-3 include Cyanine Blue 4938 (manufactured by Dainichiseika), Monastral Blue BG (manufactured by ICIIm), Hostaverum Blue BG (manufactured by Nippon Hoechst), Sumikablint Cyanine Blue GN- Examples include 0-3 (Sumiman Kagaku@ri), Lionor Blue GLA (manufactured by Toyo Ink ■), KET Blue 104, and KET Blue II+ (manufactured by Dainippon Ink ■).The method of coating the surface of the pigment with silica is strange. Pigment:silica = +00:0, weight ratio of 1 to 100:10, preferably 100:3 to 100, is charged into a nonyl mixer or super mixer, and the mixture is rotated at high speed.

The amount of the pigment used in the present invention is preferably 0.1 to 10.0 parts by weight per 100 parts by weight of the resin.

More preferably, the amount is 2.0 to 4.0 parts by weight. If the amount is less than 0.1 parts by weight, coloring properties cannot be obtained and sufficient image density cannot be secured, and if it is more than 10 parts by weight, the dispersion of the pigment in the resin will be reduced and the charging characteristics will be deteriorated.

The charge control of the toner may be performed using the binder resin or pigment itself, or, if necessary, a charge control agent that does not cause problems in color reproduction may be used in combination. For example, metal chelates such as gold-containing dyes, acidic or electron-withdrawing organic substances, etc. can be used.

Note that any known binder resin can be used as the binder resin of the present invention. For example, polystyrene, poly-α-methylstyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer Coalescence, styrene-maleic acid copolymer, styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-α-methyl chloroacrylate copolymer, styrene-acrylonitrile-acrylic ester copolymer Styrenic resins (unipolymers or copolymers containing styrene or styrene substitutes), epoxy resins, urethane-modified resins, etc.
Epoxy resin, silicone-modified epoxy resin, polyester resin, vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic acid resin, phenyl resin, polyethylene, polypropylene, iomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-
Ethyl acrylate copolymers, xylene resins, polyvinyl butyral resins, terpene resins, phenol resins, aliphatic or ring hydrocarbon resins, etc. can be used alone or in combination. Particularly preferred in this case are styrene-acrylic ester resins, styrene-methacrylic ester resins, and polyester resins.

In addition, when using this developer as a two-component toner,
Any known carrier can be used. For example, surface-oxidized or unoxidized iron or iron and metals such as nickel, copper, zinc, cobalt, manganese, chromium, rare earths, and alloys thereof, or oxides and ferrites can be used. Moreover, those whose surfaces are coated with various resins can also be used. In addition, if necessary, a fluidity modifier such as colloidal silica may be added to the toner in an amount of 0.01 to 6.
．． 000 parts by weight (more preferably 0.1 to 1.0 parts by weight)
6) May be added.

action The effect of this technical means is as follows.

That is, by coating the surface of the pigment with negatively charged hydrophobic silica, the positive charge that the pigment itself has is neutralized or the pigment is charged negatively. Then, the polarity is matched with that of the toner to prevent generation of oppositely charged toner.

Furthermore, since silica is hydrophobic, it has good moisture resistance even under high humidity conditions. As a result, it has excellent charging characteristics and resistance to deterioration over time.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that the present invention is not limited to these examples. In the following, all parts of the formulation are by weight.

Example 1゜・Styrene-acrylic acid ester resin 100 parts (trade name Hymer TBL-500, manufactured by Sanyo Chemical Co., Ltd.)・Polypropylene wax 4 parts (trade name Viscole 550-P, manufactured by Sanyo Chemical Co., Ltd.)・Charge control agent
4 parts (product name Kaya Charge N-31 manufactured by Nippon Kayaku Co., Ltd.)・C. I. Pigment Blue 15-3 3 parts The above materials are uniformly dispersed using a Henschel mixer, the dispersion is melt-kneaded using a twin-screw extruder, etc., and after cooling, it is finely pulverized using a jet mill, etc., and the average particle size is averaged using a classifier. Diameter 1
A 1 um classified product was obtained. To this classified product, 0.3% hydrophobic silica (trade name R972, manufactured by Nippon Aerosil Co., Ltd.) was externally added using a Henschel mixer to obtain the cyan toner of the present invention. Transfer this toner to a ferrite carrier (PL-150,
(manufactured by Nippon Tetsuko Co., Ltd.) to form a developer. Using this developer, you can print a racer printer (product name: KX-P4).
450. Manufactured by Matsushita Electric Co., Ltd.), 20,000 coins were produced in a row. The image quality of the obtained print is 1 to 20.00.
It was good through all 0 sheets.

Example 2゜・Styrene-acrylic acid ester resin 100 parts (Himer TB-1000 manufactured by Sanyo Chemical Co., Ltd.)・Polypropylene wax 4 parts (Viscol 5 parts)
50-P (manufactured by Sanyo Chemical)・Charge control agent
4 parts (Kaya Charge N-3 manufactured by Nippon Kajimi)・C. I. Pigment Blue 15-3 3
The surface is coated with 3% negatively charged hydrophobic silica based on the above pigment.

A cyan toner was obtained in the same manner as in Example 1. A similar printing test was also conducted. This also had good print quality throughout the range of 1 to 20,000 ff.

Comparative Example 1°・100 parts of styrene-acrylic acid ester resin (Himer T B-1000 manufactured by Sanyo Chemical Co., Ltd.)・4 parts of polypropylene wax (Viscol 55
0-P (manufactured by Sanyo Chemical)・Charge control agent
4 parts (Kaya Charge N-3 manufactured by Nippon Kajimi)・C. I. Pigment Blue 15-3 3 parts (KET Blue-104 manufactured by Dainippon Ink ■) Example 1. A cyan toner was obtained in a similar manner.

A similar printing test was also conducted. After about 7,000 sheets were produced, the print quality was good, but after about 13,000 sheets, dirt became noticeable in the non-image area, and after 20,000 sheets, the print quality became unusable. This is considered to be due to the fact that the pigment has a chargeability opposite to that of the toner. That is, the ratio of the oppositely charged toner increases with printing, and this is thought to be the cause of the staining of the non-image area.

Comparative Example 2゜・100 parts of polyester resin (
Hymer ES-508 (manufactured by Sanyo Chemical), 4 parts polypropylene wax (Viscol 550-P
Manufactured by Sanyo Chemical Co., Ltd.) / Charge control agent
4 parts (Kaya Charge N-3 made by Nippon Kakami)・
C. I. Pigment Blue 15-3 3 parts (KE
TB]ue-III Manufactured by Dainippon Ink ■) Example 1. A cyan toner was obtained in a similar manner.

A similar printing test was also conducted. The print quality was good when printing about 5,000 sheets, but when printing about 10,000 sheets, dirt became noticeable in the non-image area.
After 1,000 sheets, the print quality became unusable.

This is also considered to be due to an increase in the amount of oppositely charged toner.

Effects of the Invention As described above, by using the cyan toner of the present invention, it is possible to suppress the generation of reversely charged toner and obtain a negatively charged toner having excellent charging characteristics, resistance to deterioration over time, and resistance to moisture. It's coming. Therefore, a cyan image with good print quality can be provided for a long period of time.

Furthermore, the pigment of the present invention can be widely used as a negatively chargeable component cyan toner.

Claims (3)

[Claims] (1) A negatively chargeable cyan toner for color electrophotography, which contains a colorant and a binder resin as main components, and the colorant is a phthalocyanine-based blue organic pigment whose surface is coated with negatively chargeable hydrophobic silica. . (2) The pigment is C.I. I. pigment blue 15-3
The toner according to claim 1, which is classified as: (3) The toner according to claim 1, wherein the pigment is contained in a proportion of 0.5 to 10% by weight based on the binder resin.