JPS62109061A - Toner for developing electrostatic image - Google Patents

Abstract

PURPOSE:To keep the amt. of electrostatic charge at a fixed value in continuous copy and printing, and to obtain picture images having high quality continuously by incorporating a colorant, styrene, acrylic resin, polypropylene and ethylene/ propylene copolymer. CONSTITUTION:The toner contains a colorant, styrene, acrylic resin, polypropylene, and ethylene/propylene copolymer. The content of polypropylene and ethylene/propylene copolymer is 1-15, and 0.5-5wt%, respectively. Polypropylene has effect for preventing reduction of electrostatic charge during continuous copy and printing. Necessary content thereof is >=1wt%. As the result, scattering of toner in the neighborhood of a developing machine is prevented. But, picture image density may sometimes, be reduced due to increase of electrostatic charge by the incorporation of polypropylene. Therefore, the upper limit of the content of polypropylene is defined at 15wt%. By incorporating ethylene/propylene copolymer together, the increase of the electrostatic charge of a toner is prevented, and a toner causing hardly reduction of electrostatic charge is provided.

Description

Detailed Description of the Invention C. Industrial Field of Application The present invention relates to a toner for developing an electrostatic charge image on a photoreceptor by electrophotography used in copying machines, printers, etc. The present invention relates to a long-life electrostatic image developing toner that exhibits little deterioration of the electrostatic charge image.

C. Prior Art] In the conventional electrophotographic method, an electric latent image is formed on a photoreceptor using a photoconductive substance by exposure to light.

Development is performed using toner charged with static electricity due to frictional charging, and after the toner is transferred to a transfer material such as a sheet of paper, it is fixed by heat or pressure to obtain a visible image. The most commonly known method for triboelectrically charging a toner is to charge the toner by stirring the toner together with magnetic powder called a carrier.

And by the combination of the above carrier and toner.

Various different polarities and amounts of charge can be applied to the toner.

[Problem that the invention seeks to solve]

However, with conventional toner, when copying and printing are continued continuously, the developer consisting of toner and carrier deteriorates. In other words, it is mainly a change in the absolute value of the amount of charge on the toner.

Also, variations occur in the amount of charge of each toner. For example, when the absolute value of the amount of charge increases.

Since the charge of the electrostatic latent image on the photoreceptor is constant, the total amount of charge of the toner that develops the latent image is also constant, so a small amount of toner fills up the latent image, and the density of the resulting visible image is descend. In addition, if there is a variation in the charge amount of 1-toner 1 (container 1), toner particles with a small charge amount will fly off to areas other than the electrostatic latent image on the photoreceptor, and the resulting visible image will be This results in a lot of fog.Furthermore, when the toner loses its chargeability, the toner scatters around the developing machine, contaminating the inside of the machine.In this way, when using conventional toner, continuous copying and printing , the amount of charge is kept constant,
It was not possible to continuously obtain high-quality images.

[Means for solving problems]

The present invention solves the above-mentioned drawbacks of conventional toners, and provides a toner for developing electrostatic images that can maintain a constant charge amount even during continuous copying and printing and continuously obtain high-quality images. The purpose is to

In order to achieve the above object, the present invention employs the following technical means.

Namely, 9 colorants, styrene/acrylic resin.

It contains polypropylene and ethylene propylene copolymer.

Preferably, the content of polypropylene and ethylene propylene copolymer is 1 to 15% by weight and 0% by weight, respectively.
．． It is 5 to 5% by weight.

In the present invention, polypropylene has the effect of preventing the charge amount of the toner from decreasing during continuous copying and printing, and must be contained in an amount of 1% by weight or more. As a result, toner scattering around the developing machine is prevented. However, the upper limit is 1 because the inclusion of polypropylene increases the charge amount and reduces the density of one image.
5-fold view%. It has also been found that by containing an ethylene propylene copolymer, it is possible to prevent the charge amount of the toner from increasing and to obtain a toner with less decrease in the charge amount. If the ethylene propylene copolymer is less than 0.5% by weight, the above effect cannot be expected;
If it is contained in excess of

This is inconvenient because it causes fogging on the image and degrades the quality of one image. This is presumed to be due to the large variation in the amount of charge of each toner particle.

〔Example〕

Raw materials used (11 Styrene/acrylic resin Fujikura Kasei HTR-02 (2) Polypropylene Sanyo Kasei 660P (3) Ethylene propylene copolymer EXXON VISTALON 5600 (4) Nigrosine dye Orient Bontron N003 (5) Carbon Bra, 7 Mitsubishi Kasei #44 The above raw materials were kneaded for 30 minutes with a Ni-Goo equipped with a heating roller, and then pulverized and classified into 2 parts.
A toner having a particle size distribution of 20 IJm was obtained. This toner was mixed with a commercially available ferrite carrier and used as a developer in a continuous copying test of 30,000 sheets.
Amount of change in charge amount.

Image density and fog were evaluated. These results are also listed on the right side of the table above.

In addition, in order to compare with the toner of the present invention described above, 9 Comparative Examples 1 to 3 were prepared.
A toner was prepared. The compositions were the same as in Examples 1 to 5, except that one or both of the polypropylene and ethylene propylene copolymers were missing, and the procedures for producing the toner and developer were also the same. The composition and evaluation results are shown in the table together with Examples. The polyethylene used in Comparative Examples 2 and 3 was 200P manufactured by Mitsui Petrochemical.

As is clear from the table, Comparative Examples contain polypropylene and polyethylene either singly or in combination, but Comparative Example 2 shows a large change in the amount of charge and a significant decrease in the density of one image. , the occurrence of fogging phenomenon is observed. In Comparative Example 1, although the fixing temperature range and fog were good, the amount of change in the amount of charge was large and the density of one image decreased. This leads to drawbacks such as a decrease in image quality and a shortened lifespan. Comparative Example 3 contained a composite of polypropylene and polyethylene, and although the fixing temperature range was slightly improved, the other evaluation items were not satisfactory. In contrast, Example 1~
Since all of the fixing temperature ranges shown in No. 5 are 20 to 40° C. or higher, they can be applied to a very wide range of models. Therefore, the charged Bg coral is extremely small and 2
The image density remains the original 1.4 even after 30,000 copies have been continuously copied.
Because the standard is maintained, each image is extremely clear and of high quality. Furthermore, there was almost no occurrence of flaking, indicating that the toner has a long life.

〔Effect of the invention〕

As described above, the toner for developing electrostatic images of the present invention is
Significantly improves charge amount stability during continuous copying (printing), which was previously insufficient.

Since there is little change in the charge amount of the toner, copies (prints) with uniform image density can be obtained, and the toner has a longer lifespan than conventional toners.

Claims (3)

[Claims] (1) A toner for developing electrostatic images characterized by containing a colorant, a styrene/acrylic resin, polypropylene, and an ethylene propylene copolymer. (2) The toner for developing electrostatic images according to claim 1, wherein the contents of polypropylene and ethylene propylene copolymer are 1 to 15% by weight and 0.5 to 5% by weight, respectively. (3) The toner for developing an electrostatic image according to claim 1 or 2, wherein the colorant contains a nigrosine dye and is a positively chargeable toner.