JP3065653B2 - Color toner for electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a color toner for electrophotography used for developing an electrostatic latent image such as an electrophotography, and provides a color toner for electrophotography capable of obtaining sufficient color mixture and transparency upon fixing. the purpose of a storage elastic modulus at a temperature of 100 ° C. is ^{15 5 ~10 6 dyn / cm 2} , and the temperature at which the loss elastic modulus exhibits a 10 ⁴ dyn / cm ²
T ₁ , 5 × 10 ³ When the temperature at dyn / cm ² is T ₂ , T ₁ = 10
The configuration is such that 0 to 180 ° C. and ΔT = T ₂ −T ₁ = 0 to 20 ° C.

[Industrial Application Field] The present invention relates to an electrophotographic color toner used for developing an electrostatic latent image such as an electrophotographic image.

As an electrophotographic method, a method described in US Pat. No. 2,297,691 is well known. This generally uses a photoconductive insulator (such as a photo-condrum), applies a uniform electrostatic charge to the photoconductive insulator by corona discharge or the like, and applies various methods to the photoconductive insulator. To form an electrostatic latent image by irradiating the latent image with a fine powder called toner, visualize the latent image, transfer the toner image to paper or the like as necessary, and then pressurize. The toner image is fixed on a recording medium such as paper by means of heat, irradiation of solvent, vapor, light, or the like, to obtain a copy.

[Prior Art] Toner is obtained by dispersing a colorant and a charge controlling agent in a binder resin made of a natural or synthetic polymer.
It is a fine powder pulverized to about 30 μm, usually mixed with a carrier substance (carrier) such as iron powder or ferrite powder to form a developer, which is used for the development.
The toner image is formed only with the toner.

The fixing is to fuse the toner of the toner image and fix it to the recording paper, and as the method, hot-pressure fixing, oven fixing, and light fixing are known,
Any of these fixing methods can be preferably used.

When a color multicolor image is obtained by electrophotography, generally, three color toners of yellow, magellan, and cyan are used.
This is realized by superposing toner images of each color and mixing the colors.

Therefore, at the time of fixing, the quality of the color mixture between the toners affects the image quality.

[Problems to be Solved by the Invention] However, in such a conventional color toner,
Since the toner was manufactured without considering the viscoelastic properties of the toner, which significantly affects the color mixing and transparency of the toner, many of the toners did not show sufficient color mixing and transparency at the time of fixing.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an electrophotographic color toner capable of obtaining sufficient color mixing and transparency upon fixing.

Means for Solving the Problems In order to achieve the above object, the present invention provides a color print by fixing a toner image obtained using an electrophotographic method on a recording medium using heat. The temperature at which the storage elastic modulus at a temperature of 100 ° C. is 10 ⁵ to 10 ⁶ dyn / cm ² and the loss elastic modulus is 10 ⁴ dyn / cm ^2, which is an electrophotographic color toner used in an apparatus. T ₁ , 5 × 10 ³ dyn / cm ²
When the temperature at the of T ₂ showing _{a, T 1 = 100~180 ℃, ΔT} =
It was configured such that T ₂ −T ₁ = 0 to 20 ° C.

 Hereinafter, the present invention will be described in more detail.

In order to obtain sufficient color mixing and transparency at the time of fixing the toner, it is necessary that the toner has a characteristic that the viscosity sharply decreases when the temperature exceeds the fixing temperature. The sharp decrease in viscosity causes the upper and lower portions of the toner layer to mix (color-mix) in a short time, thereby increasing the transparency. In order to impart the above properties to the toner, it is desired that the viscosity is suddenly reduced when the temperature exceeds the melting point of the toner. That is, it is desired that the toner has a large loss elastic modulus with respect to temperature.

The fixing of the toner slightly varies depending on the roll temperature of the fixing machine and the process speed, but generally heat of 100 to 180 ° C. is applied to the toner.

Therefore, it is desired that the toner rapidly changes its viscosity at 100 to 180 ° C. and changes to a liquid state. Further, since it does not contribute to fixing at a temperature of 100 ° C. or less, it is desirable to use a material which hardly causes caking or blocking from the viewpoint of storage stability. That is,
The storage elastic modulus at 100 ° C is 10 ⁵ dyn / cm ² or more.
The temperature at which the loss elastic modulus is 10 ⁴ dyn / cm ² is 10 ⁶ dyn / cm ² or less, and the
T ₁ , 5 × 10 ³ When the temperature at dyn / cm ² is T ₂ , T ₁ = 10
Those in which 0 to 180 ° C. and ΔT = T ₂ −T ₁ = 0 to 20 ° C. are desired. The temperature (T ₁ ) is 10 when the loss modulus is 10 ⁴ dyn / cm ²
Even if the temperature is 0 to 180 ° C., as long as the viscosity does not change abruptly with the temperature change, for example, the toner of ΔT = T ₂ −T ₁ = 40 ° C. is inferior in color mixing property and transparency. A smaller one is desirable.

As the toner binder resin, an epoxy resin, a styrene-acrelate ester aggregate, a polyester resin, a polyurethane resin, and the like can be considered, and a polyester resin is most suitable for satisfying the transparency and offset property of the resin. Further, in order to improve the offset resistance, it is desired that the polyester resin contains a component composed of a trifunctional or higher polyfunctional monomer and has a chloroform-insoluble content of 1 to 20% by weight. Further, in order to improve the storage stability (blocking resistance) of the toner, the glass transition temperature of the resin is desired to be 50 ° C. or higher, and the glass transition temperature of the resin is 70 ° C. or lower to enable fixing at 100 to 180 ° C. It is necessary to be.

As the pigment, quinacridone, monoazo, bisazo, perylene, naphthol, copper phthalocyanine and the like can be used. Further, as the charge control agent, a gold-containing dye, a fatty acid ester, or a compound having an amino group may be added.

The toner used in the present invention can be manufactured by a conventionally known method. That is, the binder resin, the pigment, and the charge control agent are melted and kneaded by, for example, a pressure kneader, an extruder, or the like, and are uniformly dispersed, and, for example, classified by an air classifier to obtain a desired toner. it can.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

Example 1 Polyester resin having chloroform-insoluble content of 10% by weight (glass transition temperature: 60 ° C.) 95 parts by weight Yellow: Kayaset Yellow 963 (Nippon Kayaku) 5 parts by weight Magenta: Red 130 (Nippon Kayaku) 5 parts by weight Part Cyan: Blue 814 (Nippon Kayaku) 5 parts by weight The resin and the dye are mixed and stirred by a ball mill, melt-kneaded by an extruder heated to 100 ° C., cooled and solidified, and coarsely pulverized by a pulverizer. Furthermore, it was finely pulverized with a jet mill. The resulting fine powder was classified with an air classifier to obtain yellow, magenta, and cyan toners of 5 to 20 μm.

 The viscoelastic properties of these toners are shown below.

Using this toner as a carrier in 5% by weight and resin-coated ferrite powder (average particle size of 40 μm) as 95% by weight, three-color printing can be performed simultaneously, and a printing test was performed using a laser printer employing a hot roll fixing machine. went. As a result, it was found that the printed image was excellent in color mixing property and transparency.

 It was also found that the storage stability was excellent.

Example 2 A toner was obtained in exactly the same manner as in Example 1 except that a polyester resin having a glass transition temperature of 65 ° C. was used as a binder resin, and a printing test was performed in the same manner as in Example 1. It was found that it was excellent in transparency and storage stability.

 The viscosity elastic properties of these toners are shown below.

Comparative Example 1 Styrene having a glass transition temperature of 60 ° C. as a binder resin
A toner was obtained in exactly the same manner as in Example 1 except that an acrylic resin was used. The viscosity properties are shown below. As a result of performing a printing test in the same manner as in Example 1, ΔT was 5 ° C. or more, and there was no sudden change in viscosity with respect to temperature change. Therefore, the color mixing property of the printed image was poor and a desired color could not be reproduced.

Comparative Example 2 As a result of using a toner having a storage elastic modulus of 5.0 × 10 ⁴ dyn / cm ² at a temperature of 100 ° C., the storage stability was reduced to 30 ° C. and 80%.
After standing in a% RH environment for one month, toner blocking occurred.

Comparative Example 3 As a result of using a toner having a storage elastic modulus of 6.2 × 10 ⁶ dyn / cm ² at a temperature of 100 ° C., it was found that the fixability was poor.

Example 3 A toner was obtained in exactly the same manner as in Example 1 except that a polyester resin having a chloroform-insoluble content of 5% by weight was used as a binder resin, and a printing test was performed in the same manner as in Example 1. As a result, a printed image was obtained. It was found that the color mixing property and the transparency were excellent, and the storage stability was also excellent.

Comparative Example 4 A toner was obtained in exactly the same manner as in Example 1 except that a polyester resin having a chlorofomur-insoluble content of 25% by weight was used as a binder resin, and a printing test was performed in the same manner as in Example 1. It turned out to be inferior.

Comparative Example 5 A toner was obtained in exactly the same manner as in Example 1 except that a polyester resin having a chloroform-insoluble content of 0.5% by weight was used as a binder resin, and a printing test was performed in the same manner as in Example 1. Offsets occurred in the heat roll after one sheet.

Comparative Example 6 A toner was obtained in exactly the same manner as in Example 1 except that a polyester resin having a glass transition temperature of 45 ° C. was used, and a printing test was performed in the same manner as in Example 1. As a result, it was found that storage stability was poor. Was.

Comparative Example 7 A toner was obtained exactly in the same manner as in Example 1 except that a polyester resin having a glass transition temperature of 75 ° C. was used, and a printing test was performed in the same manner as in Example 1. As a result, it was found that the fixability was poor.

Comparative Example 8 A toner was obtained in exactly the same manner as in Example 1 except that a ferrite carrier having an average particle size of 80 μm was used as a carrier, and a printing test was performed in the same manner as in Example 1. As a result, the resolution of a printed image was determined. Turned out to be inferior.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a color toner exhibiting sufficient color mixing and transparency at the time of fixing using heat.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-190868 (JP, A) JP-A-60-55358 (JP, A) JP-A-62-178277 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (2)

(57) [Claims] 1. An electrophotographic color toner used in an apparatus for obtaining a color print by fixing a toner image obtained by using an electrophotographic method on a recording medium by using heat, wherein the temperature is 100 ° C. At a storage elastic modulus of 10 ⁵ to 10 ⁶ dyn / cm ² and a loss elastic modulus of 10 ⁴ dyn / cm ²
T ₁ , when the temperature at which 5 × 10 ³ dyn / cm ² is indicated is T ₂ , T ₁ =
A color toner for electrophotography, wherein the temperature is 100 to 180 ° C. and ΔT = T ₂ −T ₁ = 0 to 20 ° C. 2. The color toner according to claim 1, wherein the binder resin comprises a polyester resin containing a component of a trifunctional or higher polyfunctional monomer, and the polyester resin has a chloroform-insoluble content of 1 to 20% by weight. The color toner for electrophotography according to claim 1.