JP3127601B2 - Electrophotographic cyan 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 a cyan toner for electrophotography for forming a color image and an image forming method using the same, and more particularly, to an image forming method for forming a clear and high-saturation cyan toner image. About.

[0002]

2. Description of the Related Art Conventionally, as a cyan toner for color,
C. I. Pigment Blue 15, 15: 1, 1
5: 2, 15: 3, 15: 4, 15: 6, etc. are used alone. Since these color materials have a reddish tint, other color materials are used in combination to obtain an ideal cyan color. For example, C.I. I. Pigment Blue 15-based coloring material and a pigment such as anthraquinone or C.I.
I. Pigment Green 7 is known. (JP-A-1-310361 and 2-1)
However, in these cases, the bleeding, weather resistance, electrical properties, dispersibility in the binder resin, and the like of the pigment are not sufficient, and C.I. I. Green-based coloring materials such as Pigment Green 7 have a drawback that, since they have different spectral characteristics from copper phthalocyanine, a decrease in chroma on the high density side cannot be suppressed when they are mixed. On the other hand, aluminum phthalocyanine has been proposed as a pigment in an electrophotographic developer (JP-A-57-90058). Aluminum phthalocyanine is a coloring material having spectral characteristics close to that of copper phthalocyanine, but has poor dispersibility in a binder resin used for a toner, and cannot sufficiently exhibit the characteristics of the coloring material.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and an object of the present invention is to provide a toner for forming a clear and highly saturated cyan color. An object of the present invention is to provide an image forming method for forming a color image using the image forming method.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that when a phthalocyanine-based coloring material treated by a flushing method is used, the dispersibility in a binder resin is improved. It has been found that when a fixed image formed by using satisfies a specific relationship with respect to the optical density and the reflectance, a clear and highly saturated cyan color image can be obtained, and the present invention has been completed. Was.

That is, in the image forming method of the present invention, a step of forming a latent image on a latent image holding member, a step of developing the latent image on the latent image holding member using a developer, and a step of developing a developed toner image And a step of fixing the transferred toner image, wherein an aluminum phthalocyanine compound represented by the following formula (I), which is treated by a flushing method, is used as a developer. Comprising at least a cyan toner for electrophotography,
400-70 using only the electrophotographic cyan toner.
The specular gloss at an incident angle of 75 ° in the visible wavelength region of 0 nm is 40% or more, and the optical density I.I. D. When a fixed image satisfying the following formula (1) is formed, the difference A between the maximum reflectance and the minimum reflectance in the visible wavelength range and the optical density I.V. D. Satisfy the following expression (2). 1.4 ≦ I. D. ≦ 2.0 (1) | A | ≧ −20 × I. D. +92 (2) In the present invention, the specular gloss is JIS Z
871 [Gs (75 °)] obtained by the measuring method according to Method 2 of 8741.

[0006]

Embedded image

[0007] The cyan toner for electrophotography of the present invention used in the above image forming method comprises at least an aluminum phthalocyanine compound represented by the above formula (I); I.
Pigment Blue 15, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 2, C.I.
I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4 and C.I. I. Pigment Blue 1
5: 6.

Hereinafter, the present invention will be described in detail. The cyan toner for electrophotography used in the present invention contains a binder resin and a coloring material as main components. As the coloring material, an aluminum phthalocyanine compound represented by the above formula (I) is preferably used. . Although this aluminum phthalocyanine can be used alone, it can also be used in combination with copper phthalocyanine. When combined with copper phthalocyanine, saturation is increased and a clear hue is exhibited, which is preferable. Preferred specific examples of copper phthalocyanine include C.I. I. Pigment Blue 1
5, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4 and C.I. I. Pigment Blue 15: 6.

When the above-mentioned aluminum phthalocyanine is produced by a usual method, the dispersion unit is about 1 μm, and the dispersibility in the binder resin is poor. Therefore, in the present invention, it is necessary to treat aluminum phthalocyanine by a flushing method. By this flushing treatment, the dispersion unit of the coloring material becomes smaller than 0.1 μm, the dispersibility in the binder resin is improved, and the color characteristics are also improved. In addition, when copper phthalocyanine is used in combination with aluminum phthalocyanine, it is preferable to perform flushing also on copper phthalocyanine, whereby the difference between the maximum reflectance and the minimum reflectance in the visible wavelength range is increased, and the color characteristics are reduced. The improvement effect is improved.

The flushing method is a method in which an aqueous paste of a pigment and a resin are kneaded, a resin in an aqueous phase is transferred to a resin phase, and thereafter, water is removed.
It can be performed by adding a resin used for the production of a toner to the wet cake of the coloring material, and kneading the mixture using a kneader, three rolls or both. As a result, the moisture in the wet cake is replaced by the melted resin, the resin penetrates between the aggregates of the color material particles, and the existing air is removed. As a result, it is considered that the dispersibility of the coloring material in the binder resin is improved.

In the present invention, the blending amount of the phthalocyanine-based coloring material is preferably 5% by weight or less in the binder resin. In particular, the amount of aluminum phthalocyanine is preferably not more than 3.6% by weight, and when aluminum phthalocyanine and copper phthalocyanine are used in combination, the total amount of both is preferably not more than 5.0% by weight.

In the present invention, known binder resins can be used. For example, styrene such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, and aminostyrene, and derivatives or substituted homopolymers and copolymers thereof, methacrylic acid and methacrylic acid such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate Ester homo- or copolymers, acrylic acid and methyl acrylate, ethyl acrylate,
Butyl acrylate, homo- or copolymers of acrylates such as 2-ethylhexyl acrylate, butadiene, dienes such as isoprene, acrylonitrile,
Vinyl monomers such as vinyl ethers, maleic acid and maleic esters, maleic anhydride, vinyl chloride and vinyl acetate, or copolymers with other monomers, and olefins such as ethylene and propylene Alternatively, a copolymer, polyester, polyamide, polyurethane, or the like can be used alone or in a mixed form.

Of these, polyester resins, styrene-acrylic resins, and styrene-butadiene resins can be preferably used. Any polyester can be used, and can be obtained by reacting a polyhydric alcohol component with a polybasic acid component. Examples of the polyhydric alcohol component include alkylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, cyclohexanedimethanol, and neopentyl glycol. , Bisphenol A, hydrogenated bisphenol A, tripropylene glycol, bisphenol A
Ether, 2,2-bis (4-β-hydroxyethoxyphenyl) propane, 2,2 ′-(1,4-phenylenebisoxy) bisethanol, 1,1-dimethyl-2,
2 '-(1,4-phenylenebisoxy) bisethanol, 1,1,1', 1'-tetramethyl-2,2'-
And aromatic diols such as (1,4-phenylenebisoxy) bisethanol. Further, as the polyhydric alcohol component, a trihydric or higher polyhydric alcohol can be used in a small amount. As polyhydric alcohols that can be used together,
1,1,1-trimethylolethane, pentaerythritol, glycerin, 1,1,1-trimethylolpropane, 1,1,4,4-tetramethylolbutane, 1,
2,4-trihydroxybutane and the like. Examples of the polybasic acid component include divalent carboxylic acids, acid anhydrides and lower alkyl esters, and specifically, for example, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, gluconic acid, Phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid and their acid anhydrides and their monomethyl esters, dimethyl esters, monoethyl esters, diethyl esters, methyl ethyl esters, Lower alkyl esters such as monopropyl ester and dipropyl ester.

Further, as the styrene-acrylic resin,
Styrene-n-butyl acrylate copolymer, styrene-n-butyl methacrylate copolymer and the like can be used.
These binder resins have a Tg (glass transition temperature) of 50 to 8
Those having a temperature of 0 ° C and a softening point of 80 to 150 ° C are preferred. When the Tg is lower than 50 ° C., blocking occurs when the toner is stored,
When the temperature is higher than ° C., the fixing temperature becomes high. When the softening point is lower than 80 ° C., hot offset occurs at the time of fixing. On the other hand, when the softening point is higher than 150 ° C., the fixing temperature becomes high, and it becomes impossible to withstand use.

The cyan toner for electrophotography used in the present invention can be produced by a known method. That is, first, the water-containing paste of the coloring material is heated and kneaded at a temperature of at least 100 ° C. in a heating and pressing kneader together with a binder resin to remove water. The kneading time in this flushing step is preferably 5 minutes or more, and particularly preferably kneading at a temperature range of 100 to 110 ° C. for 10 minutes. During kneading, the pressure is 2 kg.
/ M ² or more. The resin-dispersed pigment thus obtained is then melted and kneaded with the binder resin. After cooling, the kneaded material is crushed by a coarse crusher, for example, to an average particle size of about 1 mm, and then by a fine crusher.
For example, it may be pulverized to a volume average particle size of about 7 to 9 μm and further classified to obtain a desired particle size.

An external additive is optionally added to the toner obtained as described above. As the external additive, any known additives can be used. For example, inorganic oxide fine powder such as silica, aluminum oxide, and titanium oxide, or synthetic resin fine powder can be used.

In the present invention, as described above, regarding the fixed image formed using only the cyan toner for electrophotography, the surface glossiness (75 °) at an incident angle of 75 ° in a visible wavelength region of 400 to 700 nm is obtained. 40% or more,
And the optical density I.I. D. Satisfies the above formula (1), the difference A between the maximum reflectance and the minimum reflectance in the visible wavelength range and the optical density I.I. D. Must satisfy the above expression (2). If the difference A between the maximum reflectance and the minimum reflectance is smaller than the above range, sufficient saturation cannot be obtained.

[0018]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. Examples 1 to 7 and Comparative Examples 1 to 3 The following were used as the binder resin in the present invention. (A) Bisphenol A ethylene oxide adduct-terephthalic acid condensation product (Tg: 60 ° C., softening point: 107
° C) (b) Bisphenol A propylene oxide adduct-
Terephthalic acid-trimellitic acid condensation product (Tg: 63
° C, softening point: 120 ° C) (c) Styrene-n-butyl methacrylate copolymer (Tg: 65 ° C, softening point: 120 ° C)

As a coloring material, aluminum phthalocyanine (Al-Pc) is Sanyo A-13 pht.
alocyanine (manufactured by Sanyo Pigment Co., Ltd.)
Examples of copper phthalocyanine include C.I. I. Pigment Blue (PB) 15, 15: 1, 15: 3 and 15: 6
It was used. These were subjected to a flushing process using a binder resin used for the production of a toner, then the binder resin was added to the obtained pigment kneaded material, mixed with a Henschel mixer, and then melt-kneaded with an extruder. After cooling, the mixture was roughly pulverized, then finely pulverized by a jet mill, and pulverized to obtain a toner having an average particle diameter of 7 μm. In the case of Comparative Example 1, kneading was performed directly without performing flushing. In the case of Comparative Example 2, C.I. I. Pigment Blue (PB) 15: 3 and C.I. I. Pigment Green (PG) 7 was used.

An image was formed using the toner obtained as described above and evaluated. That is, the silica fine powder (R
812, manufactured by Aerosil Co.) as an external additive, and mixed with a mixer. 8 parts by weight of the obtained toner composition and a particle size of 5
0 μm silicone resin-coated ferrite carrier 100
The weight was mixed with a V blender for 10 minutes to prepare a developer.

The obtained developer is used in a copying machine (A color
630 remodeled machine, manufactured by Fuji Xerox Co., Ltd.), copying was performed only in the blue mode, and an unfixed image was formed. This unfixed image was subjected to pressure roll temperature 155 using a pressure roll fixing machine.
The fixing was performed at a process speed of 160 mm / sec. At that time, the specular gloss becomes 40% or more, and the optical density becomes 1.4.
The heat roll temperature to 150 to 17
The temperature was variably adjusted to 0 ° C., and fixing was performed. The optical density is XR
It was measured using item 404 (manufactured by X-Rite). For the formed fixed image, the spectral reflection spectrum was measured using a Shimadzu Color Pall System (manufactured by Shimadzu Corporation) (40).
0 nm to 700 nm), and the difference A between the maximum reflectance and the minimum reflectance was determined. Table 1 shows the results. The color tone evaluation was performed by sensory evaluation based on the sample of Example 1.

[0022]

[Table 1]

[0023]

According to the image forming method of the present invention, since a phthalocyanine pigment treated by a flash method is used in a developer, a clear and high-saturation cyan color image is formed, especially when aluminum phthalocyanine is used. Can form a cyan toner image with high color purity. Therefore, the present invention is suitable for forming a full-color image without causing color turbidity due to multi-color superposition.

Continuation of the front page (56) References JP-A-57-90058 (JP, A) JP-A-58-158649 (JP, A) JP-A-59-204839 (JP, A) JP-A-49-107741 (JP, A) , A) JP-A-60-133459 (JP, A) JP-A-60-138562 (JP, A) JP-A-1-159666 (JP, A) JP-A-1-310361 (JP, A) JP-A-6-127847 (JP, A) JP-A-4-39671 (JP, A) JP-A-4-2422752 (JP, A) JP-A-62-255956 (JP, A) A) JP-A-63-301960 (JP, A) JP-A-3-48863 (JP, A) JP-T-60-501760 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) G03G 9/08

Claims (2)

(57) [Claims] 1. A step of forming a latent image on a latent image holding member, a step of developing the latent image on the latent image holding member using a developer, and a step of transferring a developed toner image onto a transfer member In an image forming method having a step of fixing a transferred toner image, at least a cyan toner for electrophotography containing an aluminum phthalocyanine compound represented by the following formula (I), which is treated by a flushing method, is used as a developer. Using only the cyan toner for electrophotography, the specular gloss at an incident angle of 75 ° in the visible wavelength region of 400 to 700 nm is 40% or more, and the optical density I.I. D. When a fixed image satisfying the following formula (1) is formed, the difference A between the maximum reflectance and the minimum reflectance in the visible wavelength range and the optical density I.V. D. Satisfies the following expression (2). 1.4 ≦ I. D. ≦ 2.0 (1) | A | ≧ −20 × I. D. +92 (2) 2. An aluminum phthalocyanine compound represented by at least the above formula (I); I. Pigment Blue 15, C.I. I. Pigment Blue 15: 1,
C. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 1
5: 4 and C.I. I. Pigment Blue 15: 6. A cyan toner for electrophotography, comprising a coloring material selected from the group consisting of Pigment Blue 15: 6.