JPH02166461A - Electrophotographic developer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a developer for electrostatic images in electrophotography, and more specifically, it is used to produce high-quality images in an electrophotographic process using a photoreceptor made of an organic photoconductor. Regarding the developer to be applied.

[Prior art 1 Conventionally, as an electrophotographic method, U.S. Patent No. 2,297゜68
Specification No. 1, Japanese Patent Publication No. 42-23910, Japanese Patent Publication No. 4
3-24748, etc., as a boat fishing method, an electrical latent image is formed on a photoreceptor by various means using a photoconductive substance, and then the latent image is The toner image is developed using a developer (hereinafter referred to as toner), the toner image is transferred to a transfer material such as paper as necessary, and then fixed using a heated roller or the like to obtain a copy.

The step of forming an electric latent image in this electrophotographic process will be described in more detail in a-5e and a-9i.

After uniformly charging a photoreceptor made of an organic photoconductor or the like by corona charging or direct charging using a conductive roller, etc., an optical image of the object to be copied, a dot pattern using laser light, etc. is exposed, and the electrostatic charge is removed. It is used to obtain a latent image, and it is known that two active substances such as ozone, NO, and (x=1.2) are generated during the charging process.

[Problems to be Solved by the Invention] However, ozone and NOx generated in the above process not only pose environmental health problems, but also act on the photoreceptor, causing potential fluctuations, increased residual potential, and blurring of images. This adversely affects electrophotographic properties such as flow and images, and is a factor that reduces the durability of the photoreceptor. Particularly in recent years, there has been a shift from conventional inorganic materials to organic materials for photoreceptors.

Organic photoreceptors are susceptible to ozone and NOx, and are generally hole-transporting, and are often used with negative charges that generate a large amount of ozone, making the generation of ozone and NOX a serious problem. .

In order to solve the above problems, (1) a fan is provided in the main body of the copying machine to exhaust generated ozone and NOx; (2) Introducing a process that constantly removes deteriorated parts of the photoreceptor surface; (3) Selecting organic photoconductive materials that are resistant to ozone and NOx; (4) Adding antioxidants or deterioration inhibitors to the photoreceptor. A method of adding . However, problems such as (1) the exhaust efficiency, (2) the mechanical durability of the photoreceptor, and (3) and (4) ozone resistance and the difficulty of achieving both NOx resistance and photoreceptor characteristics are encountered. have.

[Means and effects for solving the problems] The present invention solves the above-mentioned problems and provides a toner that improves durability against corona charging products such as ozone and NO on a photoreceptor.

The present invention contains a hydrotalcite compound, which is a compound that exhibits an acid-accepting effect, in the toner and constantly supplies it to the surface of the photoreceptor, thereby preventing the influence of corona products containing generally acidic substances from reaching the photoreceptor. This is to make sure that there is no such thing. Furthermore, in addition to the above compounds, phenolic, amine,
The combined use of one or more antioxidants selected from phosphorus-based and sulfur-based compounds is also effective in increasing the durability of the photosensitive drum against corona products.

The structure of the hydrotalcite compound used in the present invention is positively charged 1Mqz(t-x)Ai)2x(O
H) 41 layer and negatively charged [C032-X 1H2
0] layer, and the CO32 in the structure
It is known that - has ion exchange properties and adsorbs fusion by easily substituting with other 7 ions.

Since the antioxidant selected from hydrotalcite compounds and phenol-based, amine-based, phosphorus-based, and sulfur-based compounds used in the present invention is added to the toner, it must not impair the developability of the toner. , can be processed into fine powder, does not affect the color tone in the case of single-color toner, and has a melting point of at least 5 to prevent toner blocking.
The necessary conditions are that the temperature be 0°C or higher.

Table 1 shows specific examples of hydrotalcite compounds in the present invention, and Table 2 shows specific examples of phenol-based, amine-based, phosphorus-based, and sulfur-based antioxidants.

Table 1 Examples of hydrotalcite compounds■ MgoIAj)o, 3(OH)2(CO3)0.
ISO, 5? H20■ Mgo, 5Ai)o, 2
(OH)2 (CO3)O, +oO, BIH20■
Nge, zsARo, 25(DH)2 (CO3)
o, 3250.50H20■) Igo, axAi'
o, +1(OH)z(C03)o,ossO,47H2
0 [Example] Specific examples of the present invention are shown below.

All parts in the examples are parts by weight.

Example 1 still.

= The above materials were thoroughly mixed in a blender and then kneaded with two rolls heated to 150°C. After allowing the mixed material to cool naturally, it is coarsely ground using a cutter mill.

Silica fine powder (product name Aerosil 1200.Specific surface area 200m2
/g, manufactured by Aerosil) 0.5 part of the black fine powder 1
00 parts to prepare a toner.

0.1 part of hydrotalcite compound (1) having the following structural formula was mixed with 100 parts of the toner thus obtained to obtain compound (1) Mgo, rsAj? o, 25(OR)2 (CO3
) Images were evaluated on an electrophotographic copier using a 0.1250.83H20 organophotoreceptor. The organic photoreceptor used has a charge generation layer and a charge transport layer laminated on an aluminum cylinder.The charge generation layer is formed by coating a paint containing an azo pigment dispersed in a butyral resin, The transport layer is formed by applying a paint in which a benzidine compound is dissolved in a polycarbonate resin. The structural formulas of the charge generating material and the charge transporting material are shown below.

(Left below) The evaluation method was to not operate the exhaust system inside the copier at all.
An durability test of 4,000 continuous sheets was conducted under conditions where the influence of ozone and NOx due to corona charging was accelerated, and the sharpness of the image was evaluated.

In addition, in the 0 table, a product without addition of compound (i) was evaluated using the same method as Comparative Example 1. @ in the table indicates clear, 0 indicates slightly clear,
Δ indicates that the image is not clear but is legible, and × indicates that it is not legible.

The results are shown in Table 3.

Table 3: The charge generation layer is formed by applying a paint in which an azo pigment is dispersed in a butyral resin, and the charge transport layer, which is the surface layer, is formed by applying a paint in which a hydrazone compound is dissolved in a polycarbonate resin. ing. The structural formulas of the TrL charge generating material and the charge transporting material are shown below.

(The following is a blank space) Example 2 100 parts of the toner obtained in the same manner as in Example 1 were mixed with the combinations of compounds shown in Table 4, and the images were evaluated using an electrophotographic copying machine using an organic photoreceptor.

The organic photoreceptor used was one in which a charge generation layer and a charge transport layer were laminated on an aluminum cylinder.The durability was evaluated in the same manner as in Example 1, and the results are shown in Table 5. Comparative Example 2 was evaluated as Comparative Example 2, in which no antioxidant was added.

Table 5 Grind using a pulverizer using a jet stream.

The powder was further classified using an air classifier to obtain a fine powder with a particle size of 5 to 20 μm, which was used as a toner. After adding 0.3 parts of hydrophobic colloidal silica to 100 parts of this toner, a combination of a hydrotalcite compound shown in Table 6 and a fermentation inhibitor was further mixed.

(Left below) Example 3 The above materials were thoroughly mixed in a blender, and then kneaded with two rolls heated to 150°C. After the kneaded material was left to cool naturally and coarsely pulverized with a cutter mill, 5 parts of externally added toner listed in E was mixed with 100 parts of iron powder carrier having an average particle size of 50 to 80 grams, and the following composition was prepared. Image evaluation was performed by applying the image to an electrophotographic printer (having a process of negative charging, image scanning, and reversal development) using a semiconductor laser (wavelength: 788 nm) using an organic photoreceptor as a light source.

The evaluation method was the same as in Example 1, and Comparative Example 3 was evaluated without adding the combination of hydrotalcite compound and antioxidant.

The results are shown in Table 7.

(Margin below) Table [Effects of the Invention] As described above, when the toner of the present invention is used, the durability of the photoreceptor is improved and clear images can be obtained over a long period of time.

Claims (2)

[Claims] (1) An electrophotographic developer applied to an electrophotographic process in which the photoreceptor is an organic photoconductor, characterized by containing a hydrotalcite compound having the following structural formula. Mg_(_1_-_x_)Al_x(OH)_2CO_
3_x_/_2・mH_2O0<x≦0.5m: Positive number (2) The electrophotographic developer according to claim (1), which contains at least one antioxidant selected from phenol-based, amine-based, phosphorus-based, and sulfur-based compounds and having a melting point of 50° C. or higher.