JP3018441B2 - Negatively chargeable cyan toner for electrophotography - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a negatively chargeable cyan toner for electrophotography used for color electrophotography.

2. Description of the Related Art As a color toner for electrophotography, a toner in which various dyes and pigments are dispersed in a binder resin is widely used.
Of these color toners, a phthalocyanine pigment is generally used as a colorant for a cyan toner for electrophotography. This pigment is most suitable for expressing cyan. In other words, when expressed in the L ^* a ^* b ^* color system, L ^* = 40 to 60 a ^* = 0 to -20 b ^* =-40 to -60
In other words, it is difficult to express the tint of a colorant other than a phthalocyanine pigment. Pigments classified as CI Pigment Blue 15-3 are most suitable in terms of color.

Problems to be Solved by the Invention However, phthalocyanine inherently has a tendency to be positively charged, and when used for a negatively chargeable toner, deteriorates image quality over time, particularly stains in non-image areas. Easy to invite.
This is presumably because reverse-charged toner is easily generated. As a method of preventing this, as a toner composition,
A method of internally adding a large amount of a negatively chargeable charge agent to a binder resin, a method of externally adding a large amount of a negatively chargeable fine powder to a toner, or a method of using both in combination. However, when a large amount of the charging agent is internally added, an excess of the charging agent that cannot be completely dispersed in the binder resin is likely to be present alone in the toner powder. Therefore, the environment resistance is poor, and a fogging phenomenon in which the non-image portion is stained occurs. In particular, the degree of deterioration is large at high temperature and high humidity. This is considered to be because the charging agent present alone in the toner powder embraces moisture, lowering the chargeability of the toner, and easily generating a reverse-charged toner. Further, since the charge agent is expensive, the use of a large amount increases the cost of the toner. When a large amount of fine powder is externally added, the fixability of the toner to paper is reduced. In addition, the environmental resistance is poor, and the image density tends to decrease. In particular, the degree of deterioration is large at low temperature and low humidity. This is probably because the low humidity causes the toner to have an abnormally high chargeability due to the action of the external additive.

In addition, in a two-component developer in which toner is mixed with iron powder or ferrite powder called a carrier at a fixed ratio and both are frictionally charged, the surface of the carrier is coated with a positively chargeable resin to increase the chargeability of the toner. There is also a method of suppressing the generation of the oppositely charged toner. However, this method has a small effect of improving image quality unless the coating amount is increased. When the coating amount is increased, the possibility that the coating agent is peeled off with time increases, and when the coating agent is peeled off, the coating agent is mixed with the toner in the developer, the charge amount of the toner is reduced, and the oppositely charged toner is easily generated, which causes fogging. .

The present invention solves the above-mentioned disadvantages of the prior art, expresses an optimal cyan color, does not need to add a large amount of negatively charged electric agent into the toner, and does not need to externally add a large amount of charged fine powder. Another object of the present invention is to provide a negatively chargeable cyan toner for electrophotography which has excellent charge stability and can prevent a decrease in image density and generation of fog.

Means for Solving the Problems In order to achieve this object, the negatively chargeable cyan toner for electrophotography of the present invention, the surface of the phthalocyanine pigment, aluminum oxide fine particles having a particle size of 10 to 100 nm, or a particle size of 10 to 100 nm. ~ 100nm titanium oxide fine particles, or particle size 10 ~ 100
It is composed of aluminum oxide fine particles of 10 nm and titanium oxide fine particles of 10 to 100 nm in particle diameter.

Action With this configuration, the aluminum oxide fine particles and the titanium oxide fine particles have conductivity. By coating the surface of the pigment with these fine particles, the pigment itself can be suppressed from being positively charged and the polarity of the toner can be reduced. Will have no effect.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

As the aluminum oxide fine particles used in this example, white fine particles of 10 to 100 nm are preferable. Examples of such fine particles include Aluminum Oxide C (Nippon Aerosil Co., Ltd.).

As the phthalocyanine pigment, a pigment belonging to CI Pigment Blue 15-3 is preferable in terms of cyan color. Examples of the pigment include Cyanine Blue 4938 (Dainichi Seika Kogyo Co., Ltd.), Monastral Blue BG (ICI), Hostaperm Blue BG (Hoechst), Sumika Print Cyanine Blue GN-O-3 (Sumitomo Chemical Industries, Ltd.) )), Lionol Blue GLA (Toyo Ink Manufacturing Co., Ltd.), KET Blue 104, KET Blue 111 (Dainippon Ink and Chemicals, Inc.)
And so on.

The method of coating the surface of the pigment with the aluminum oxide fine particles is prepared by charging a Henschel mixer or a super mixer in a weight ratio of pigment: aluminum oxide fine particles = 100: 0.1 to 100: 10, more preferably 100: 3 to 100: 7, Perform by high-speed rotation.

The amount of the pigment used in this embodiment as a toner composition is desirably 0.1 to 10 parts by weight based on 100 parts by weight of the resin. More preferably, it is 2.0 to 4.0 parts by weight. If the amount is less than 0.1 part by weight, sufficient color density cannot be obtained and a sufficient image density cannot be secured. If the amount is less than 10 parts by weight, the dispersion of the pigment in the resin is reduced, and the charging characteristics are deteriorated.

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

In addition, as the binder resin of the present invention, all known resins can be used. For example, polystyrene, poly-α-methylstyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene・ Maleic acid copolymer, styrene / acrylate copolymer,
Styrene / methacrylic acid ester copolymer, styrene
Styrene-based resins (mono- or copolymers containing styrene or styrene-substituted products) such as α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer, epoxy resin, urethane-modified epoxy resin, silicon Modified epoxy resin, polyester resin, vinyl chloride resin, styrene vinyl acetate copolymer, rosin-modified maleic resin, phenyl resin, polyethylene, polypropylene, iomer resin, polyurethane resin, silicone resin, ketone resin, ethylene / ethyl acrylate copolymer , A xylene resin, a polyvinyl butyral resin, a terpene resin, a phenol resin, an aliphatic or alicyclic hydrocarbon resin or the like can be used alone or as a mixture. Particularly preferred in this case is styrene
There are acrylic ester resins, styrene / methacrylic ester resins, and polyester resins.

Known carriers can be used as the carrier. For example, surface oxidized or unoxidized iron or iron and nickel,
Metals such as copper, zinc, cobalt, manganese, chromium, rare earth and alloys thereof, oxides and ferrites can be used. Those whose surfaces are coated with various resins or the like can also be used.

If necessary, a fluidity modifier such as colloidal silica may be added to the toner in an amount of 0.01 to 6.00% by weight, more preferably 0.1 to 1.0% by weight.

Hereinafter, a specific example will be described. The contents of the number of parts are all parts by weight and are not limited to these examples.

Example 1 Binder resin Styrene / acrylate resin 100 parts (trade name: Himer TBL-500: manufactured by Sanyo Chemical Industry Co., Ltd.) Wax polypropylene 4 parts (trade name: Viscol 550-P: Sanyo Chemical Industry Co., Ltd.) )) ・ Charging agent 4 parts (Kayacharge N-3: manufactured by Nippon Kayaku Co., Ltd.) ・ Coloring agent 3 parts CI Pigment Blue 15-3 [5% by weight of aluminum oxide fine particles based on the above pigment (Surface is coated) (trade name CI Pigment Blue 15-3: KET Blue-111 Aluminum oxide fine particles manufactured by Dainippon Ink and Chemicals, Inc .: Aluminum Oxide C manufactured by Nippon Aerosil Co., Ltd.) The dispersion was uniformly dispersed, melt-kneaded with a twin-screw extruder or the like, cooled, and then finely pulverized with a jet mill or the like, and a classified product having an average particle size of 11 μm was obtained using a classifier. 0.3% by weight of hydrophobic silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was externally added to and mixed with the classified product using a Henschel mixer to obtain a cyan toner of the present invention.

Example 2 A cyan toner was obtained in the same manner as in Example 1 except that the binder resin in Example 1 was changed to the following.

Binder resin 100 parts of saturated polyester resin (trade name: Polyester HP-300: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) Example 3 Example 1 was repeated except that the binder resin in Example 1 was changed to the following. In the same manner as in the above, a cyan toner was obtained.

Binder resin Styrene / acrylic acid resin 100 parts (trade name ZSR-1008: manufactured by Fujikura Kasei Co., Ltd.) Example 4 Except that the pigment in Example 1 was changed to the following:
A cyan toner was obtained in the same manner as in Example 1.

Colorant CI Pigment Blue 15-3 3 parts (trade name: KET Blue-104: manufactured by Dainippon Ink and Chemicals, Inc.) The surface treatment of the pigment is the same as in Example 1.

Also, as Comparative Examples 1 to 4, except that the pigments in Examples 1 to 4 were not surface-treated with aluminum oxide fine particles,
Cyan toners were obtained by the same materials and manufacturing methods as in Examples 1 to 4, respectively.

Each of these toners was used as a ferrite carrier (trade name)
FL-150 Powder Tech). Using these developers, a laser printer (trade name KX-P4450 manufactured by Matsushita Electric Industrial Co., Ltd.)
Table 1 shows the results of fog density measurement for each predetermined number of sheets printed.

As can be seen from Table 1, the toners of Examples 1 to 4 had good image quality during continuous printing. That is, the image density was small and stable from the initial printing to 20,000 sheets, and the value was satisfactory. Fog was similarly satisfactory.

The toners of Comparative Examples 1 to 4 had relatively good image densities, but fog began to be noticeable during print running, and finally had print quality unusable.

By coating the surface of the phthalocyanine pigment with aluminum oxide as described above, when used as a two-component developer, the generation of a reversely charged toner can be suppressed, and a cyan toner having excellent aging property can be obtained. Therefore, it is possible to provide a cyan image with good print quality for a long time. Further, it is possible to provide a cyan toner having good print quality over a long period of time as a negatively chargeable one-component toner.

Next, another embodiment in the case of coating with titanium oxide will be described.

Titanium oxide fine particles used in other examples, 10
White fine particles of 100100 nm are preferred. These fine particles include Tit
anium Dioxide P25 (Nippon Aerosil Co., Ltd.), STT-30
D (Titanium Industry Co., Ltd.), TT0-55, ET-500W (Ishihara Sangyo Co., Ltd.).

As the phthalocyanine pigment, a pigment belonging to CI Pigment Blue 15-3 is preferable in terms of cyan color. Examples of the pigment include Cyanine Blue 4938 (Dainichi Seika), Monastral Blue BG (ICI), Hostaperm Blue BG (Hoechst), Sumika Print Cyanine Blue GN-0-3 (Sumitomo Chemical), and Lionol Blue GLA.
(Toyo Ink), KET Blue 104, KET Blue 111 (Dainippon Ink) and the like.

The method of coating the surface of the pigment with the titanium oxide fine particles is such that the pigment: titanium oxide fine particles = 100: 0.1 to 100: 10 by weight, more preferably 10: 100, is added to the Henschel mixer or super mixer.
Charge at 0: 3 to 100: 7 and perform by high speed rotation.

The amount of the pigment used in the present invention as a toner composition is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the resin. More preferably, it is 2.0 to 4.0 parts by weight. If the amount is less than 0.1 part by weight, sufficient color density cannot be obtained and a sufficient image density cannot be secured. If the amount is less than 10 parts by weight, the dispersion of the pigment in the resin is reduced, and the charging characteristics are deteriorated.

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

As the binder resin in this embodiment, the same resin as in the embodiment using aluminum oxide can be used. For example, polystyrene, poly-α-methylstyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene・ Styrenes such as maleic acid copolymer, styrene / acrylic acid ester copolymer, styrene / methacrylic acid ester copolymer, styrene / α-chloromethyl acrylate copolymer, styrene / acrylonitrile / acrylic acid ester copolymer Resin (a homopolymer or copolymer containing styrene or a substituted styrene),
Epoxy resin, urethane modified epoxy resin, silicon modified epoxy resin, polyester resin, vinyl chloride resin,
Styrene vinyl acetate copolymer, rosin-modified maleic resin, phenyl resin, polyethylene, polypropylene, iomer resin, polyurethane resin, silicone resin, ketone resin, ethylene / ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, terpene resin,
A phenol resin, an aliphatic or alicyclic hydrocarbon resin or the like can be used alone or as a mixture. Particularly preferred in this case are styrene / acrylate resin, styrene / methacrylate resin, and polyester resin.

When the present toner is used as a two-component toner, a known carrier can be used. For example, surface oxidized or unoxidized iron or iron and nickel,
Metals such as copper, zinc, cobalt, manganese, chromium and rare earths and alloys thereof, or oxides and ferrites can be used. Those whose surfaces are coated with various resins or the like can also be used.

Further, if necessary, a fluidity modifier such as colloidal silica may be added to the toner in an amount of 0.01 to 6.00% by weight, more preferably 0.1 to 1.0% by weight.

Note that the present invention is not limited to these examples. Hereinafter, all the contents of the number of parts in the composition are parts by weight.

Example 5-Binder resin Styrene / acrylate resin 100 parts (trade name: Himer TBL-500: manufactured by Sanyo Chemical Co., Ltd.)-Wax polypropylene 4 parts (trade name: Viscol 550-P: manufactured by Sanyo Chemical Co., Ltd.)-Charging agent 4 parts (trade name Kayacharge N-3: manufactured by Nippon Kayaku Co., Ltd.)-Colorant 3 parts CI Pigment Blue 15-3 [Coated with 5% by weight of titanium oxide fine particles based on the above pigment] (Product CI CI Pigment Blue 15-3: KET Blue-111 Titanium oxide fine particles manufactured by Dainippon Ink Co., Ltd .: Titanium Dioxide P25 manufactured by Nippon Aerosil Co., Ltd. After melt-kneading and cooling, the mixture was finely pulverized with a jet mill or the like, and a classified product having an average particle size of 11 μm was obtained using a classifier. 0.3% by weight of hydrophobic silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was externally added to the classified product using a Henschel mixer to obtain a cyan toner of the present invention.

Example 6 A cyan toner was obtained in the same manner as in Example 1, except that the binder resin in Example 1 was changed to the following.

-Binder resin 100 parts of saturated polyester resin (trade name: Polyester HP-300: manufactured by Nippon Synthetic Chemical Co., Ltd.) Example 7 Same as Example 1 except that the binder resin in Example 1 was changed to the following. Thus, a cyan toner was obtained.

-Binder resin Styrene / acrylic acid resin 100 parts (trade name: ZSR-1008: manufactured by Fujikura Kasei Co., Ltd.) Example 8 Except that the pigment in Example 1 was changed to the following:
A cyan toner was obtained in the same manner as in Example 1.

-Colorant C.I. Pigment Blue 15-3 3 parts (trade name: KET Blue-104: manufactured by Dainippon Ink) The surface treatment of the above pigment is the same as in Example 1.

Example 9 A cyan toner was obtained in the same manner as in Example 1 except that the titanium oxide fine particles in Example 1 were changed to the following.

Colorant CI Pigment Blue 15-3 3 parts The amount of titanium oxide fine particles added to the pigment is the same as in Example 1.

(Trade name: titanium oxide fine particles: ET-500W manufactured by Ishihara Sangyo Co., Ltd.) Comparative Examples 5 to 8 are the same as Examples 5 to 8 except that the pigments in Examples 5 to 8 are not surface-treated with titanium oxide fine particles. Thus, a cyan toner was obtained.

Each of these toners was used as a ferrite carrier (FL-15
0, manufactured by Powdertech Co., Ltd.) to obtain a developer. A laser printer (trade name KX-
P4450 (manufactured by Matsushita Electric Industrial Co., Ltd.), 20,000 sheets were continuously printed, and the fog density was measured for each predetermined number of sheets.

The toners of Examples 5 to 9 had good image quality during continuous printing. That is, the image density is from the initial print to 2
The change was small and stable in the 0,000 sheets, and the value was satisfactory. Fog was similarly satisfactory.

Although the image densities of the toners of Comparative Examples 5 to 8 were relatively good, fog began to be noticeable in the middle of print running, and finally the print quality was unusable.

By coating the surface of the phthalocyanine pigment with titanium oxide as described above, the generation of a reversely charged toner can be suppressed, and a negatively charged toner having excellent durability can be obtained. Therefore, it is possible to provide a cyan image with good print quality for a long time. Further, it can be widely used as a negatively chargeable one-component cyan toner.

In this example, although the surface of the phthalocyanine pigment was coated with titanium oxide and aluminum oxide alone, the same effect can be obtained by coating a mixture of titanium oxide and aluminum oxide.

The present invention provides a phthalocyanine pigment having a particle size of 10
Aluminum oxide fine particles of ~ 100nm, or particle size of 10 ~ 1
The titanium oxide fine particles having a diameter of 100 nm or the aluminum oxide fine particles having a particle diameter of 10 to 100 nm and the titanium oxide fine particles having a particle diameter of 10 to 100 nm are coated, so that the aluminum oxide fine particles and the titanium oxide fine particles have conductivity. So, by coating the surface of the pigment with these fine particles,
Since the pigment itself can be suppressed from being positively charged and the pigment does not affect the polarity of the toner, the optimal cyan color is expressed, and a large amount of negatively charged electric agent is not added to the toner internally. Also, even without externally adding a large amount of charged fine powder, the charge stability is excellent, and a decrease in image density and generation of fog can be prevented.

Continuation of the front page (56) References JP-A-63-258957 (JP, A) JP-A-63-152671 (JP, A) JP-A-50-63939 (JP, A) JP-A-60-254156 (JP, A) , A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/09

Claims (3)

(57) [Claims] 1. A negatively chargeable cyan toner for electrophotography, comprising a phthalocyanine pigment whose surface is coated with fine particles of aluminum oxide and a binder resin, wherein the particle size of the fine particles of aluminum oxide is 10 to 100 nm. A negatively chargeable cyan toner for electrophotography, comprising: 2. A negatively chargeable cyan toner for electrophotography, comprising a phthalocyanine pigment whose surface is coated with fine particles of titanium oxide and a binder resin, wherein the particle diameter of the fine particles of titanium oxide is 10 to 100 nm. A negatively chargeable cyan toner for electrophotography, comprising: 3. A negatively chargeable cyan toner for electrophotography, comprising a phthalocyanine pigment whose surface is coated with aluminum oxide fine particles and titanium oxide fine particles, and a binder resin, wherein the particle size of the aluminum oxide fine particles is A negatively chargeable cyan toner for electrophotography, wherein each of the titanium oxide fine particles has a particle size of 10 to 100 nm.