JPH11184142A - Electrophotographic toner, manufacture thereof and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrophotographic toner which can be inexpensively manufactured and used for a flash fixing system and a heat roll fixing system in common. SOLUTION: At least binder resin and colorant are included in this electrophotographic toner. Then, the loss elasticity of the toner is <=2×10<7> dyn/cm<2> when it is measured at 100 deg.C and <=2×10<5> dyn/cm<2> when it is measured at 180 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for electrophotography and a method for producing the same, and more specifically, it can be produced at low cost and can be used commonly for a flash fixing method and a heat roll fixing method. In other words, the present invention relates to an electrophotographic toner that does not select a fixing method in a toner fixing step and a method of manufacturing the same. The present invention also relates to an image forming method using such an electrophotographic toner. The electrophotographic toner of the present invention can be used for various imaging apparatuses using an electrophotographic method, for example, an electrophotographic copying machine,
It can be advantageously used as a developer in electrophotographic printers, electrostatic printers and the like.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic method widely used in a copying machine, a printer, a printing machine and the like generally has a positive or negative surface on a photoconductive insulator such as a photosensitive drum. Starting from giving a uniform electrostatic charge. After such a uniform charging step, an electrostatic image is formed by irradiating a photoconductive insulator with a light image by various means to partially erase the electrostatic charges on the insulator. For example, an electrostatic latent image corresponding to image information can be formed on a photoconductive insulator by irradiating a laser beam and erasing surface charges of a specific portion. Next, a fine powder of developer called toner is attached to the latent image portion where the electrostatic charge remains on the photoconductive insulator to visualize the latent image. Finally, the toner image thus obtained is generally electrostatically transferred to a recording medium such as recording paper in order to form a printed matter, and is fused and fixed by application of heat, light, pressure and the like. .

As is well known, the transfer image fixing step, which is the final step of the electrophotographic system, is performed using various methods and apparatuses. At present, as a general method, a flash fixing method in which a toner is melted and fixed by light irradiation such as a flash light, and a heat roll fixing method in which a toner is melt-pressed while applying pressure to a toner with a heating roller are well known. The flash fixing method has an advantage in that the toner is melted by exposure, so that the toner can be fixed in a non-contact manner with a recording sheet or the like. This is effective for fixing an image on a recording sheet having a glue on the fixing surface of the recording paper. Another advantage is that even if the thicknesses of the sheets are different, the fixing can be performed with the same flash light energy without changing the fixing energy. On the other hand, the heat roll fixing method has an advantage that a wide color reproduction range can be secured when color toner is used because the toner fixing surface becomes smooth and irregular reflection on light can be prevented. ing. Therefore, this fixing method is excellent in fixing an image such as a natural image, and is advantageous in achieving high image quality.

In the conventional electrophotographic printer using the flash fixing method or the heat roll fixing method, the fixing characteristics required for the toner are different depending on the fixing method. Therefore, the electrophotographic printer is suitable for each apparatus and each fixing method. Dedicated toner has been supplied and used. Therefore, in the related art, the toner has to be prepared for each fixing method, so that the types of toners increase, and it is impossible to reduce the cost of the toner by mass production. In addition, printers incorporating both a flash fixing mechanism and a heat roll fixing mechanism have been proposed in order to take advantage of the respective fixing methods. However, in such a printer, a toner supply system is switched according to the fixing method. An additional mechanism is required, further complicating the equipment and handling. Therefore, at present, it is desired to provide an electrophotographic toner that can be used commonly for the flash fixing method and the heat roll fixing method.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic toner which can be manufactured at a low cost and can be used commonly for a flash fixing system and a heat roll fixing system. . Another of the present invention
One object is to provide a method for producing the electrophotographic toner provided by the present invention.

Another object of the present invention is to provide an image forming method using the electrophotographic toner provided by the present invention. Other objects of the present invention will be easily understood from the following detailed description.

[0007]

According to one aspect of the present invention, there is provided an electrophotographic toner comprising at least a binder resin and a colorant, wherein the toner has a loss elastic modulus of at least
When measured at a temperature of 100 ° C., and a ² × 10 ⁷ dyn / cm 2 or less, when measured at a temperature of ^{140 ℃, 2 × 10 5 dyn} /
cm ² or less and measured at a temperature of 180 ° C.,
The toner for electrophotography is 1 × 10 ⁴ dyn / cm ² or more.

[0008] In another aspect of the present invention, in the method for producing the electrophotographic toner of the present invention, the binder resin and the colorant constituting the toner are required in the finally obtained toner. After the binder is melt-kneaded in an amount such that the amount of the colorant is at least twice the required amount with respect to the mixing ratio, and the colorant is dispersed in the binder resin, the binder necessary for obtaining the mixing ratio is obtained. A method for producing an electrophotographic toner, characterized in that an additional amount of a resin is further added and melt-kneading is performed again.

In another aspect of the present invention, an electrostatic latent image is formed by image exposure, a visualization is performed by developing the electrostatic latent image, a visualized image is transferred to a recording medium, and the transferred image is formed on another surface. In the method of forming an image by an electrophotographic method including each step of fixing, in the developing step of the electrostatic latent image, the electrophotographic toner of the present invention is used as a developer, and visualization is performed by using the developer. In the step of fixing the transferred image to the recording medium after transferring,
An image forming method is characterized in that a flash fixing method and / or a heat roll fixing method are used as the toner fixing method.

According to the present invention, in an electrophotographic toner containing at least a binder resin and a colorant, the toner has a loss elastic modulus within a predetermined range, so that the toner can be used for both flash fixing and heat roll fixing. An applicable toner is obtained. Further, by using this toner in an electrophotographic printer having a flash fixing mechanism and a heat roll fixing mechanism, an image forming method utilizing the advantages of both fixing systems can be realized.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies on toners applicable to both flash fixing and heat roll fixing methods for the purpose of reducing the cost of the toner. In an electrophotographic toner containing a colorant, the loss elastic modulus of the toner is 2 × 10 ⁷ dyn / cm when measured at a temperature of 100 ° C. (generally, a rise temperature of the toner in flash fixing).
² or less, and is 2 × when measured at a temperature of 140 ° C. (generally, a rise temperature of toner in heat roll fixing).
10 ⁵ dyn / cm ² or less, and when measured at 180 ° C. of the temperature (maximum temperature which is generally applicable to a heat roll fixing), by designing such that 1 × 10 ⁴ dyn / cm ² or more Found that it could achieve its intended purpose.

In fact, in the electrophotographic toner, when the loss elastic modulus of the toner is in the specific range as described above, it is possible not only to avoid inconveniences such as occurrence of offset, but also to obtain excellent print density. Can be. That is, this toner can satisfy the following relational expressions (I) and (II) before and after being subjected to the fixing process in the electrophotographic system.

[0013] In _{70 <C p <90 ... (} I) C f / C p> 1.1 ... (II) above equation, in the toner coverage of pre-C _p is the toner is subjected to a fixing process (%) And C _f is the toner coverage (%) after the toner has been subjected to a fixing process by the flash fixing method. The fact that the toner can satisfy the above relational expression indicates that the electrophotographic toner of the present invention is applicable to both the flash fixing method and the heat roll fixing method.

The present inventors have paid attention to the fact that the loss elastic modulus of the toner greatly depends on the binder resin of the toner, and by controlling the loss elastic modulus of the binder resin to a specific range, the loss of the toner is controlled. It has also been found that the modulus of elasticity can be controlled to a specific range as described above. The loss elastic modulus of the binder resin in the toner is preferably 100 ° C.
When measured at a temperature of 1 × 10 ⁷ dyn / cm ² or less,
It is less than 8 × 10 ⁴ dyn / cm ² when measured at a temperature of 140 ° C. and 5 × 10 ⁴ dyn / cm ² when measured at a temperature of 180 ° C.
³ dyn / cm ² or more.

Although the binder resin having such a specific range of the loss elastic modulus can be prepared according to various methods, the present inventors have found that (1)
A binder resin having a loss elastic modulus of 1 × 10 ⁷ dyn / cm ² or less when measured at a temperature of 100 ° C .;
It has a loss elasticity of 1 × 10 ⁵ dyn / cm ² or less when measured at a temperature of 0 ° C. and a loss elasticity of 5 × 10 ³ dyn / cm ² or more when measured at a temperature of 180 ° C. It has also been found that it is advantageous to prepare it by mixing it with a binder resin having a specific ratio.

The electrophotographic toner according to the present invention can basically have the same composition as the toner conventionally used in electrophotography. That is, the electrophotographic toner of the present invention is configured to include at least a binder resin and a colorant regardless of whether the toner is monochrome or color. The toner of the present invention is preferably obtained by dispersing a colorant, a charge controlling agent, a wax, and the like in a binder resin made of a natural or synthetic polymer substance, and then pulverizing and classifying the obtained dispersion to about 0.1. 5 to 50 μm, preferably about 1 to
It can be a fine powder having an average particle size of 15 μm. The dispersion of the colorant and the like in the binder resin can be uniformly adjusted by a relatively simple method by using the binder resin having the loss elastic modulus in the specific range as described above. The fine powder of the obtained toner is usually
After mixing with a carrier substance (carrier) such as iron powder or ferrite powder to form a developer, it can be used for visualizing an electrostatic latent image.

More specifically, the binder resin used in the electrophotographic toner of the present invention is not particularly limited as long as the physical properties of the toner described above are finally obtained when the toner is formed into a toner. Binder resin. Suitable binder resins include, for example, polyester resins, styrene resins, acrylic resins, styrene-acrylic resins, phenolic resins, silicone resins, epoxy resins, and the like. These resins may be used alone, or two or more resins may be mixed or used in combination. Further, a mixture of a linear polyester resin and a polyester resin containing a crosslinking component may be used.

The colorant to be dispersed in the binder resin includes many known dyes and pigments, and can be arbitrarily selected and used. Suitable pigments include, for example, various types of black pigments such as carbon black (channel black, furnace black, etc.) and color pigments such as benzidine-based yellow pigments, quinacodrine-based pigments, and the like.
Examples include rhodamine-based magenta pigments and phthalocyanine-based cyan pigments. These pigments may be used alone or may be used in combination to obtain a desired toner color.

Although the content of the above-mentioned colorant in the toner can be widely changed depending on the desired result, it is preferable to obtain the best toner characteristics, 2-25% by weight in consideration of force, toner shape stability, toner scattering, etc.
Range. The electrophotographic toner of the present invention further comprises:
For the purpose of controlling the charging characteristics of the toner, a charge control agent commonly used in this technical field may be included. Suitable charge control agents include, for example, an electron-donating substance such as a nigrosine dye, a fatty acid metal salt, or a quaternary ammonium salt for a positively charged toner, and an azo-based metal-containing dye, chlorinated paraffin, or chlorine for a negatively charged toner. And electron-accepting substances such as activated polyester.

Further, when the toner image is fixed by a heat roll fixing method, various waxes, for example, low molecular weight polypropylene or polyethylene can be used as a releasing agent or an anti-offset agent. Further, hydrophobic silica or titanium oxide may be used as an external additive for improving the fluidity of the toner and for other purposes. In the toner of the present invention, if necessary, in addition to hydrophobic silica or titanium oxide, other commonly used inorganic particles, resin particles, and the like may be further externally added.

The above-mentioned toner components can be used by changing the composition ratio in a wide range in accordance with the composition of a conventionally used toner. For example, generally, the binder resin is 60 to 90% by weight, the colorant is 2 to 25% by weight, the charge control agent is 1 to 5% by weight, the release agent is 0 to 5% by weight, and the external additive is 0 to 5% based on the total amount of the toner. % By weight. These toner components may be more or less than the above ranges as needed.

The electrophotographic toner according to the present invention can be prepared according to various procedures, using the above-mentioned toner components as starting materials. For example, the toner of the present invention crushes a resin mass in which a colorant or the like is dispersed,
It can be prepared using a known method such as a mechanical pulverization method for producing by classifying, or a polymerization method for producing a fine particle by polymerizing a monomer while incorporating a colorant. The toner of the present invention can be advantageously prepared by the following procedure, preferably according to a mechanical pulverization method. (1) Mixing of materials After measuring the binder resin, colorant, charge control agent, etc.,
Mix evenly with a powder mixer. As the powder mixer, for example, a ball mill or the like can be used. A colorant, a charge control agent, and the like are uniformly dispersed in the resin binder. (2) Melt kneading The obtained mixture is heated and melted, and further kneaded. A screw extruder (extruder), roll mill, kneader, or the like can be advantageously used. Fineness and uniform dispersion of the colorant particles are achieved.

In such a toner manufacturing process, the present inventors have found that the dispersibility of the colorant is improved, especially when the melt-kneading of the binder resin and the colorant is performed under specific conditions. Has been found that improved toner can be obtained. That is, according to a preferred embodiment of the present invention, the binder resin and the colorant are melt-kneaded in an amount such that the amount of the colorant is at least twice the required amount with respect to the mixing ratio required in the finally obtained toner. After dispersing the colorant in the binder resin, an additional amount of the binder resin necessary for obtaining the above-mentioned mixing ratio is further added, and the mixture is melt-kneaded again to produce a toner. The amount of the colorant to be melt-kneaded first is
There is no particular limitation as long as the concentration is at least twice as high, but in consideration of the easiness of the kneading operation and the like, the concentration is usually 2%.
It is preferably in the range of 4 to 4 times. (3) Cooling and solidification After completion of kneading, the obtained kneaded material is cooled and solidified. (4) Pulverization First, the solidified kneaded material is coarsely pulverized by a coarse pulverizer such as a hammer mill and a cutter mill, and then finely pulverized by a fine pulverizer such as a jet mill. (5) Classification After the completion of the fine pulverization, the obtained finely pulverized particles are classified in order to remove fine particles which cause a decrease in toner fluidity, toner scattering and coarse particles which cause a deterioration in image quality. As a classifier, for example, an air classifier using centrifugal force can be used. The desired spherical toner fine powder is obtained. (6) Surface treatment In the final step, hydrophobic silica or titanium oxide and, if necessary, other external additives are added to the surface of the obtained toner fine powder for improving the fluidity of the toner and for other purposes. , May be attached. As the surface treatment device, for example, a high-speed flow mixer can be used.

By using the electrophotographic toner according to the present invention, an image can be formed by using a method and an apparatus generally used conventionally. A detailed description of the image forming method is therefore omitted here,
According to the findings of the present inventors, the toner of the present invention can be advantageously applied to both the flash fixing method and the heat roll fixing method. In other words,
The toner of the present invention can be advantageously used in an electrophotographic printer having both a flash fixing mechanism and a heat roll mechanism capable of exhibiting excellent printing characteristics by utilizing the advantages of the respective fixing systems. In addition,
Flash fusing is performed first and 1 after it is completed.
By pressing a recording medium such as recording paper with a heat roll within seconds, the print density is improved, and a high print density can be realized with a small amount of toner adhered. Further, in the present invention, the temperature of the heat roll can be set to a low temperature of 70 ° C. or less, which can contribute to a reduction in power consumption.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to preferred embodiments. In the following examples, polyester resins 1 to 15 used as a binder resin in the preparation of the toner were viscoelasticity measuring devices (RDS-2, Rheometrics) as described in Table 1 below.
c), having different loss moduli when measured at 100 ° C., 140 ° C., and 180 ° C., and the loss moduli described change the molecular weight and crosslink density of the polyester resin, respectively. It was able to get by. Example 1 Preparation of Toner The following components were prepared in the stated ratios.

Binder resin: Polyester resin 1 77 parts by weight Coloring agent: Black Pearls L (trade name, manufactured by Cabot) 20 parts by weight Charge control agent: BONTRON E84 (trade name, manufactured by Orient Chemical Co.) 1 part by weight Wax: biscol 550-P (trade name, manufactured by Sanyo Chemical Co., Ltd.) 2 parts by weight These components were mixed and stirred by a ball mill,
The mixture was melt-kneaded with an extruder heated at a time. After the obtained kneaded material was cooled and solidified, it was coarsely pulverized by a pulverizer and further finely pulverized by a jet mill. The obtained fine powder was classified by an air classifier to obtain a spherical toner fine powder having an average particle diameter of 8 μm.
This toner fine powder is prepared by using a viscoelasticity measuring device (RDS-2, RDS-2).
100 ° C., 140 ° C.
When measured at 180 ° C. and 180 ° C., it had a loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “toner 1”. Example 2 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, polyester resin 2 shown in Table 1 below was used in place of polyester resin 1. This toner fine powder is supplied to a viscoelasticity measuring device (RDS-
100 ° C., 1
When measured at 40 ° C. and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “toner 2”. Example 3 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, polyester resin 3 shown in Table 1 below was used in place of polyester resin 1. This toner fine powder is supplied to a viscoelasticity measuring device (RDS-
100 ° C., 1
When measured at 40 ° C. and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “toner 3”. Example 4 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, polyester resin 4 shown in Table 1 below was used in place of polyester resin 1. This toner fine powder is supplied to a viscoelasticity measuring device (RDS-
100 ° C., 1
When measured at 40 ° C. and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “toner 4”. Comparative Example 1 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, for comparison, polyester resin 5 shown in Table 1 below was used instead of polyester resin 1. The toner fine powder was prepared by using a viscoelasticity measuring device (RDS-2, manufactured by Rheometrics).
When measured at 00 ° C., 140 ° C., and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “comparative toner 1”. Comparative Example 2 Preparation of Toner A spherical toner fine powder was prepared by repeating the method described in Example 1 above. In this example, polyester resin 6 shown in Table 1 below was used in place of polyester resin 1 for comparison. The toner fine powder was prepared by using a viscoelasticity measuring device (RDS-2, manufactured by Rheometrics).
When measured at 00 ° C., 140 ° C., and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “comparative toner 2”. Comparative Example 3 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, for comparison, polyester resin 7 shown in Table 1 below was used instead of polyester resin 1. The toner fine powder was prepared by using a viscoelasticity measuring device (RDS-2, manufactured by Rheometrics).
When measured at 00 ° C., 140 ° C., and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “comparative toner 3”. Example 5 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, polyester resin 8 and polyester resin 9 shown in Table 1 below were mixed and used at a ratio of 1: 1 (weight ratio) instead of polyester resin 1. This toner fine powder is supplied to a viscoelasticity measuring device (RDS).
-2, manufactured by Rheometric Co.) at 100 ° C.
When measured at 140 ° C. and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “toner 5”. Example 6 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, polyester resin 9 and polyester resin 10 shown in Table 1 below were mixed and used in a ratio of 1: 1 (weight ratio) instead of polyester resin 1. This toner fine powder is supplied to a viscoelasticity measuring device (RD
S-2, manufactured by Rheometric Co.)
When measured at 140 ° C., 180 ° C. and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “toner 6”. Example 7 Preparation of Toner The procedure described in Example 1 was repeated to prepare a spherical toner fine powder. In this example, polyester resin 8 and polyester resin 11 shown in Table 1 below were mixed and used in a 1: 1 ratio (weight ratio) instead of polyester resin 1. This toner fine powder is supplied to a viscoelasticity measuring device (RD
S-2, manufactured by Rheometric Co.)
When measured at 140 ° C., 180 ° C. and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “toner 7”. Comparative Example 4 Preparation of Toner A spherical toner fine powder was prepared by repeating the method described in Example 1 above. In this example, for the sake of comparison, polyester resin 8 and polyester resin 12 shown in Table 1 below were mixed and used in a 1: 1 ratio (weight ratio) instead of polyester resin 1. This toner fine powder was measured at 100 ° C., 140 ° C., and 180 ° C. using a viscoelasticity measuring device (RDS-2, manufactured by Rheometrics) and found to have the loss elastic modulus summarized in Table 2 below. I was Hereinafter, this toner fine powder is referred to as “comparative toner 4”. Comparative Example 5 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, for comparison, polyester resin 9 and polyester resin 13 shown in Table 1 below were mixed and used in a ratio of 1: 1 (weight ratio) instead of polyester resin 1. This toner fine powder was measured at 100 ° C., 140 ° C., and 180 ° C. using a viscoelasticity measuring device (RDS-2, manufactured by Rheometrics) and found to have the loss elastic modulus summarized in Table 2 below. I was Hereinafter, this toner fine powder is referred to as “Comparative Toner 5”. Comparative Example 6 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, for comparison, polyester resin 14 and polyester resin 15 shown in Table 1 below were mixed and used in a 1: 1 ratio (weight ratio) instead of polyester resin 1. This toner fine powder was measured at 100 ° C., 140 ° C., and 180 ° C. using a viscoelasticity measuring device (RDS-2, manufactured by Rheometrics) and found to have the loss elastic modulus summarized in Table 2 below. I was Hereinafter, this toner fine powder is referred to as “Comparative Toner 6”. Example 8 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, the amount of the colorant used was changed from 20 parts by weight to 2 parts by weight. This toner fine powder is prepared by using a viscoelasticity measuring device (RDS-2, manufactured by Rheometric).
When measured at 100 ° C., 140 ° C. and 180 ° C. using the above, it had a loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “toner 8”. Example 9 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, the amount of the colorant used was changed from 20 parts by weight to 10 parts by weight. This toner fine powder was measured at 100 ° C., 140 ° C., and 180 ° C. using a viscoelasticity measuring device (RDS-2, manufactured by Rheometrics) and found to have the loss elastic modulus summarized in Table 2 below. I was Hereinafter, this toner fine powder is referred to as “toner 9”. Example 10 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, the amount of the colorant used was changed from 20 parts by weight to 25 parts by weight. This toner fine powder was measured at 100 ° C., 140 ° C., and 180 ° C. using a viscoelasticity measuring device (RDS-2, manufactured by Rheometrics) and found to have the loss elastic modulus summarized in Table 2 below. I was Hereinafter, this toner fine powder is referred to as “toner 10”. Comparative Example 7 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, for comparison, the amount of the colorant used was changed from 20 parts by weight to 1 part by weight. This toner fine powder is prepared by using a viscoelasticity measuring device (RDS-2, Rheomet).
100 ° C., 140 ° C. and 180 ° C.
As a result, it had a loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “comparative toner 7”. Comparative Example 8 Preparation of Toner A spherical toner fine powder was prepared by repeating the procedure described in Example 1 above. In this example, for comparison, the amount of the colorant used was changed from 20 parts by weight to 30 parts by weight. This toner fine powder is prepared by using a viscoelasticity measuring device (RDS-2, Rheome).
100 ° C., 140 ° C. and 180 ° C.
When measured at ℃, it had a loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “Comparative Toner 8”. Example 11 Preparation of Toner The following components were prepared in the stated ratios.

Binder resin: 39 parts by weight of polyester resin 1 Colorant: Black Pearls L (trade name, manufactured by Cabot) 20 parts by weight Charge control agent: BONTRON E84 (trade name, manufactured by Orient Chemical Co.) 1 part by weight Wax: biscol 550-P (trade name, manufactured by Sanyo Chemical Co., Ltd.) 2 parts by weight These components were mixed and stirred by a ball mill,
The mixture was melt-kneaded with an extruder heated at a time. Next, 38 parts by weight of the polyester resin 1 was added to the obtained kneaded material.
Was added and melt-kneaded again in the same manner as described above. After the obtained kneaded material was cooled and solidified, it was coarsely pulverized by a pulverizer and further finely pulverized by a jet mill. The obtained fine powder was classified by an air classifier to obtain a spherical toner fine powder having an average particle diameter of 8 μm. The toner fine powder was prepared by using a viscoelasticity measuring device (RDS-2, manufactured by Rheometrics).
When measured at 00 ° C., 140 ° C., and 180 ° C., it had the loss elastic modulus summarized in Table 2 below. Hereinafter, this toner fine powder is referred to as “toner 11”.

[0028]

[Table 1]

[0029]

[Table 2]

Example 12 Printing Test Printing tests 1 to 3 were performed using the toners prepared in Examples 1 to 11 and Comparative Examples 1 to 8 according to the following procedure. Printing Test 1: Flash Fixing Printer (Model F6)
762D (manufactured by Fujitsu Ltd.), a printing test was performed by adjusting the developing bias and changing the amount of toner adhered to the recording paper. The developer carrier and toner concentration used were the same as the specifications of the printer. Printing test 2: A printing test was performed in the same manner as printing test 1. The printer used in this test was a heat roll fixing printer (product number F6708B, manufactured by Fujitsu Limited). The surface temperature of the heat roll in this printer was 140 ° C., and the offset temperature was 180 ° C. Printing test 3: A printing test was performed in the same manner as printing test 1. In this test, the printed matter obtained in the printing test 1 was heat roll-fixed within one second by the printer used in the printing test 2. The surface temperature of the heat roll of the heat roll fixing printer used in this test was 70 ° C.

The printed matter obtained in each of the printing tests was evaluated for (1) C _p , that is, the toner coverage (%) before the toner was subjected to the fixing process, and (2) C _f / C _p [C _f This is the toner coverage (%) after the toner has been subjected to the fixing process by the flash fixing method] and (3) the print density (OD) of the surface image portion. Since C _f / C _p is an evaluation item before and after the flash fixing, the printing test 1
Was evaluated only for. Printing density (OD)
Is an optical density value measured using a Sakura densitometer (PDA-65, manufactured by Konica Corporation). The print quality was evaluated by determining the print density (O
When D) was 1.2 or more, it was judged as "pass", and when it was less than 1.2, it was judged as "fail".

The following Table 3 shows the printing tests 1 to 3 described above.
This is a summary of the evaluation results. Also, attached Figure 1
Is 100 ° C. in the printing test 1 (flash fixing).
Plots the relationship between the toner loss elasticity and print density when printing
FIG. 2 shows a printing test 2 (heat roll
Fixing), the loss elastic modulus of the toner at 140 ° C. and
FIG. 3 is a graph in which the relationship between print densities is plotted.
At 100 ° C in printing test 1 (flash fixing)
Plot the relationship between the loss modulus of the binder resin and the print density.
FIG. 4 shows a printing test 2 (heat row
Loss of binder resin at 140 ° C
It is a graph plotting the relationship between elastic modulus and print density,
FIG. 5 shows the results of the printing test 1 (flash fixing).
And C_f/ C _pGraph plotting the relationship between the print density
It is.

[0033]

[Table 3]

[0034]

[Table 4]

From the results shown in Tables 1 to 3 and the results plotted in FIGS. 1 to 5, the following considerations can be derived. From FIG. 1, the printing characteristics of the printing test 1 (flash fixing) have a correlation with the loss elastic modulus of the toner at 100 ° C.
It can be seen that the higher the loss modulus, the higher the print density. In printing test 1, in order to obtain a printing density (OD) of 1.2, the loss elastic modulus of the toner at 100 ° C. was set to 2 × 10
dyn / cm ² or less.

The printing characteristics of the printing test 2 (fixing with a heat roll) also have a correlation with the loss elastic modulus of the toner, particularly with the loss elastic modulus at 140 ° C. (see FIG. 2). FIG.
Thus, in order to obtain a print density (OD) of 1.2 in the print test 2, the loss elastic modulus of the toner at 140 ° C. was set to 2 × 10 ⁵ dyn /
it is necessary to cm ² or less. If the loss elastic modulus of the toner at 180 ° C. falls below 1 × 10 ⁴ dyn / cm ² , an offset occurs. Therefore, the loss elastic modulus of the toner at 180 ° C. becomes 1 × 10 ⁴ dyn / cm ² or more. Must be set.

The printing characteristics also depend on the loss modulus of the binder resin. In the printing test 1, as the loss elastic modulus of the binder resin at 100 ° C. becomes lower, the printing test 2
As the loss elastic modulus of the binder resin at 140 ° C. decreased, the print density increased. In order to obtain a printing density (OD) of 1.2, in printing test 1, 100
It is necessary that the binder resin has a loss elastic modulus of 1 × 10 ⁷ dyn / cm ² or less at 8 ° C.
It is necessary to be 10 ⁴ dyn / cm ² or less. In order to obtain offset resistance, the loss elastic modulus of the binder resin at 180 ° C. must be 5 × 10 ³ dyn / cm ² or more. From the above, it can be seen that in order to obtain a toner applicable to both the flash fixing method and the heat roll fixing method, it is necessary to set the loss elastic modulus of the toner and the binder resin in the above-mentioned range.

Next, the toner coverage C _p (%) will be considered. Toner coverage C _p of the toner image before fixing 70
%, A high print density cannot be obtained, and conversely, if it exceeds 90%, the toner amount becomes excessive,
Waste occurs. When the toner of the present invention, an increase in toner coverage C _f during fixing, it is possible to obtain a high print density with a small amount of toner, by realizing C _f / C _p> 1.1, Printed matter of excellent print quality can be obtained.

The content of the colorant in the toner is also important.
In the toner of the present invention, the content of the colorant is 2 to 25% by weight.
Within this range, good print density and developability can be realized. 2% by weight of colorant
When the value is less than, the printing density becomes low because the coloring power of the toner is low. On the other hand, when the content of the coloring agent exceeds 25% by weight, the electric resistance and the chargeability of the toner become low, and problems such as fogging and scattering of the toner occur. Further, the toner (toner 11 of Example 11) prepared by kneading a colorant (carbon) at a high concentration in advance has improved carbon dispersibility and high toner electrical resistance even when the carbon concentration is high. In addition, fogging and toner scattering can be suppressed, the print density can be improved, and excellent printed matter can be obtained.

[0040]

As described above, according to the present invention, the toner for electrophotography obtained by setting the loss elastic modulus of the toner and the binder resin used in the toner to a specific range can be used in a flash fixing method. And a heat roll fixing method. In addition, by eliminating the limitation of the fixing method in this way, it is possible to minimize the variety of toner types that have been conventionally different, thereby enabling mass production of toner and cost reduction. Become.

[Brief description of the drawings]

FIG. 1 shows a print test 1 (flash fixation)
5 is a graph plotting the relationship between the loss elastic modulus of the toner at 0 ° C. and the print density.

FIG. 2 shows the results of a printing test 2 (heat roll fixing),
5 is a graph in which the relationship between the loss elastic modulus of the toner and the print density at 40 ° C. is plotted.

FIG. 3 shows the results of a printing test 1 (flash fixing)
5 is a graph plotting the relationship between the loss elastic modulus of the binder resin and the print density at 0 ° C.

FIG. 4 shows 1 in printing test 2 (heat roll fixing).
4 is a graph plotting a relationship between a loss elastic modulus of a binder resin and a print density at 40 ° C.

FIG. 5 shows C _f in print test 1 (flash fixing).
5 is a graph in which the relationship between / C _p and print density is plotted.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/20 108 G03G 9/08 361 381

Claims (4)

[Claims] 1. An electrophotographic toner containing at least a binder resin and a colorant, wherein the toner has a loss modulus of 2 × 10 ⁷ dyn / cm ² or less when measured at a temperature of 100 ° C. Less than 2 × 10 ⁵ dyn / cm ² when measured at a temperature of 140 ° C., and 1 × 10 ⁵ when measured at a temperature of 180 ° C.
An electrophotographic toner having a density of ⁴ dyn / cm ² or more. 2. The loss elastic modulus of the binder resin is 1 × 10 ⁷ dyn / cm ² or less when measured at a temperature of 100 ° C., and 8 × 10 ⁴ dyn / cm ² when measured at a temperature of 140 ° C. cm ² or less and measured at a temperature of 180 ° C., 5 × 10
^2. The electrophotographic toner according to claim 1, wherein the toner density is ³ dyn / cm ² or more. 3. A composition containing at least a binder resin and a colorant.
An electrophotographic toner, wherein the toner has a loss elastic modulus.
Is 2 × 10 when measured at a temperature of 100 ° C. ⁷dyn / cm^Two
Is less than 2 × 10 when measured at a temperature of 140 ° C.^Five
dyn / cm^TwoBelow and measured at a temperature of 180 ° C.
Hour, 1 × 10^Fourdyn / cm^TwoElectrophotographic toner
In the manufacturing method, the binder resin and the colorant
The amount of said colorant with respect to the mixing ratio required in the
Is kneaded in an amount that is at least twice the required amount.
The colorant was dispersed in the binder resin.
Thereafter, additional binder resin necessary for obtaining the mixing ratio is added.
It is characterized by adding more amount and re-mixing
Of producing an electrophotographic toner. 4. An electrophotographic method including the steps of forming an electrostatic latent image by image exposure, visualizing the electrostatic latent image by development, transferring the visualized image to a recording medium, and fixing the transferred image. In the method of forming an image, in the developing step of the electrostatic latent image, an electrophotographic toner including at least a binder resin and a colorant, wherein the loss elastic modulus of the toner is measured at a temperature of 100 ° C. 2 × 10 ⁷ dyn / cm ² or less, when measured at a temperature of 140 ° C., 2 × 10 ⁵ dyn / cm ² or less, and 1 × 10 5 when measured at a temperature of 180 ° C.
^In the step of fixing after transferring an image visualized by using the developer to the recording medium, using an electrophotographic toner of ⁴ dyn / cm ² or more as a developer,
An image forming method using a flash fixing method and / or a heat roll fixing method as a toner fixing method.