JP2645405B2 - roll - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a roll used in an electrophotographic copying machine or the like.

[Conventional technology]

As a developing method in an electrophotographic copying machine, there are a wet method and a dry method. Recently, the discrimination method has become more prevalent than the wet method from the viewpoint of image fixability.
As such a dry method, a method based on a triboelectric charging method as shown in FIG. 4 is used. That is, in the triboelectric charging method, as shown in the figure, the outer peripheral surface of the photosensitive drum 1 having the photoconductor surface layer is uniformly charged, and then the outer peripheral surface is exposed through the image to be copied of the object to be copied. Thereby, an electrostatic latent image is formed on the outer peripheral surface. Next, toner is supplied from the toner supply device 4 between the friction roll 2 and the developing roll 3,
The toner is developed by the frictional force of the rolls 2 and 3.
Is adhered in a charged state to the outer peripheral surface of the photosensitive drum 1, and is uniformly leveled by the layer forming blade 5, and is caused to fly by an electrostatic attraction to the electrostatic latent image on the photosensitive drum 1, and toner adheres to the electrostatic latent image In this method, a toner image is formed, transferred to the copy paper 6, and then fixed. When the toner is caused to fly by friction charging as described above, the electrical characteristics of the developing roll 3, particularly, the volume resistivity (RV) and the surface resistance (RS) are uniform and do not change with temperature and humidity. Is required. This is in order to meet the demand for higher image quality of the copied image. That is, strict requirements have been placed on the uniformity of the volume resistivity (RV) and the surface resistance (RS) described above, and the fact that their resistance does not change with temperature and humidity.

[Problems to be solved by the invention]

However, conventional developing rolls cannot meet such required characteristics.

That is, conventional synthetic resin materials for forming a developing roll are classified into two types: a type in which ionic conductive material particles are dispersed in a polymer matrix; and a dispersion type in which carbon and metal powder (fiber if necessary) are dispersed in a polymer matrix. There are different types. In a developing roll obtained by using the former synthetic resin material, as shown in FIG. 5, when there is a temperature change, the ionic conductive material particles Y dispersed in the matrix X move as shown by the arrow in the figure. . As described above, when the ionic conductive material particles Y move, the volume specific resistance and the surface resistance of the developing roll change, and as a result, the temperature dependence of these resistances increases, and electrophotographic copying using the same is performed. In such a machine, there is a problem that the image quality of the copy image is affected by the temperature. Further, the above-mentioned difficulties are also caused by changes in humidity. On the other hand, when the developing roll is formed using the latter synthetic resin material, although the above-described problem of the dependency of the resistance on temperature and humidity does not occur, it is difficult to control the resistance to a predetermined value. It is. That is, since subtle volume resistivity and the like vary depending on the filling state of carbon, metal powder, and the like, it is extremely difficult to control the volume resistivity and set the developing roll to a predetermined volume resistivity in an actual manufacturing process. . For example, as shown in FIG. 6, a change in the filling state of the conductive material particles Y such as carbon and metal powder (a part of the figure is in a chain state) greatly changes the volume resistivity and the like. The variation of the volume resistivity and the like due to the deformation of X is large. The variation of the volume resistivity due to the chain state of the conductive particles Y and the like will be described in more detail. As shown in the central part of FIG. In the case where the conductive material particles Y are arranged with small voids indicated by arrows on the right side in the drawing, a tunnel effect occurs between the conductive particles and the conductive material particles Y on the right side in the figure, which causes a reduction in volume specific resistance and the like. . It is practically impossible to appropriately control the state of the conductive material particles Y in such a state, and inevitably causes variations in the volume resistivity and the like.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a roll having uniformity in volume resistivity and the like, and having little variation in volume resistivity and the like due to temperature and humidity.

[Means for solving the problem]

In order to achieve the above object, a roll according to the present invention includes a cylindrical sleeve and an end cap that covers left and right openings of the sleeve. The cylindrical sleeve uses an insulating polymer as a matrix, and the inside of the matrix includes an insulating polymer. (A) Good conductive material particles having a volume resistivity of 10 ^-6 to 10 ^-1 Ω · cm.

(B) Hydrophobized particles of conductive zinc having a volume resistivity of 10 ¹ to 10 ⁴ Ω · cm.

That is, the present inventors have repeated research mainly on the improvement of the latter, that is, a material in which carbon, metal powder, and the like are dispersed in a polymer matrix, of the two types of conventional synthetic resin materials for forming a roll. As a result, when both a good conductive material powder having a specific volume specific resistance and particles obtained by hydrophobically treating conductive zinc having lower conductivity are contained in an insulating polymer molding material, a chain of conductive material particles is formed. The present inventors have found that when the fluctuation of the state or the dispersion state is small, it is easy to control to a predetermined semiconductivity, and the change of the volume resistivity or the like due to temperature and humidity is small.

The roll of the present invention comprises an insulating polymer molding material, a good conductive material powder having a volume resistivity of 10 ^-6 to 10 ^-1 Ωcm, and a conductive zinc having a volume resistivity of 10 ¹ to 10 ⁴ Ωcm. And the hydrophobically treated particles.

The insulating polymer molding material is not particularly limited, and any material can be used as long as it can be molded into a cylindrical sleeve shape used for a developing roll or the like. For example, it can be appropriately selected from a thermosetting synthetic resin, a thermoplastic synthetic resin, and the like. However, from the point of view of volume resistivity, the use of phenolic resins gives good results.

Examples of the good conductive material powder (component A) having a volume resistivity of 10 ^-6 to 10 ^-1 Ω · cm dispersed in the insulating polymer molding material include carbon powder, graphite powder, titanium carbide powder, and the like. Metal powder and the like can be mentioned, and they are used alone or in combination. Such a good conductive material powder preferably has a particle size of 1 μm or less from the viewpoint of the effect.

The component (B) used together with the component (A) is a hydrophobically treated particle of conductive zinc having a volume resistivity of 10 ¹ to 10 ⁴ Ω · cm. This was prepared by subjecting conductive ZnO obtained by adding a treating agent mainly composed of aluminum to zinc oxide powder and performing stirring heat treatment to a surface treatment with a titanate-based coupling agent or a fatty acid-based compound. It is preferable from the viewpoint of the effect that the flow diameter is about 0.1 to 3 μm. Here, the conductive ZnO is obtained by treating ZnO with Al, and Al is coordinated to a lattice defect of ZnO as described below.

As the titanate-based coupling agent for subjecting the conductive ZnO to a surface treatment, for example, isopropyl triisostearoyl titanate represented by the following general formula (I): Bis (dioctyl pyrophosphate) ethylene titanate represented by the following general formula (II) Isopropyl tris (dioctyl pyrophosphate) titanate represented by the following general formula (III) An isopropyl tri (N) represented by the following general formula (IV)
-Aminoethyl-aminoethyl) titanate Tetraoctyl bis (ditridecyl phosphite) titanate (C ₈ H ₁₇ —O ₄ Ti. [PO—C ₁₃ H ₂₇ ) ₂ OH] ₂ represented by the following general formula (V):
(V) Tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate represented by the following general formula (VI) Bis (dioctyl pyrophosphate) oxyacetate titanate represented by the following general formula (VI) Is raised.

The surface treatment of the conductive ZnO using the titanate-based coupling agent is performed by dissolving the titanate-based coupling agent in a solution of an organic solvent such as n-hexane, benzene, toluene, or xylene, and then adding the conductive material to the solution.
It is carried out by immersing ZnO powder or spraying the above solution onto conductive ZnO powder and then drying.

When surface treatment is performed with a fatty acid compound instead of the titanate coupling agent, a fatty acid such as stearic acid or a metal salt of stearic acid or a metal salt of a fatty acid is dissolved in an organic solvent that dissolves the fatty acid. , As before,
It can be carried out by dipping, spraying and then drying. By performing the surface treatment on the conductive ZnO in this manner, the effect of improving the moisture resistance can be obtained. In particular, when the titanate-based coupling agent is used, isopropyl triisostearoyl titanate represented by the general formula (I) or bis (dioctyl pyrophosphate) ethylene titanate represented by the general formula (II) is used. Surface treatment with a solution dissolved in n-hexane gives good results.

The component (A) has good conductivity. If the content of the component (A) is too large, for example, in the case of manufacturing a developing roll, it becomes difficult to keep the developing roll within the semiconductive range. On the other hand, if the amount is too small, the insulating property becomes too strong, so that the insulating property cannot be kept within the semiconductive range. From such a viewpoint, the component (A) and the component (B) are usually blended with the component (A) and the component (B) at the following ratio (% by weight) in the whole semiconductor polymer material composition. You.

30 ≦ A + B ≦ 80 A ≦ B 4 ≦ A ≦ 20 30 ≦ B ≦ 60 That is, as described above, by setting the ratio of the component (A) to the component (B), the developing roll is When manufactured, the volume resistivity of the roll is 10 ⁶
It comes to fall within a semiconductive range of about 10 ¹² Ω · cm. Preferably, the resistance is set within a range of 10 ⁸ to 10 ¹¹ Ω · cm.

In such a semiconductive polymer material composition, the above components (A) and (B) are mixed and mixed in a thermosetting synthetic resin or a thermoplastic synthetic resin molding material which can be a polymer matrix in the above ratio. Can be obtained.

A cylindrical article formed by extrusion molding, injection molding, compression molding, or the like of the semiconductive polymer material composition obtained in this manner (for example, using a novolak-type phenol resin as an insulating polymer molding material). FIG. 1 shows the developing roll 3 of the present invention used as a sleeve of the developing roll.
In the figure, reference numeral 9 denotes a sleeve formed by extrusion of a semiconductive polymer material composition, and reference numeral 10 denotes a metal end cap. In this developing roll 3, since the sleeve 9 is formed of the above semiconductive polymer material composition,
Uniformity of electrical characteristics (volume resistivity and surface resistivity) is provided, and the volume resistivity and the like do not change due to changes in temperature and humidity. This is considered to be due to the following reasons. That is, when both the components (A) and (B) are used in the semiconductive polymer material composition, as shown in FIG. 2, the micelle of the component (A) is replaced with the component (B). Particles are surrounded, whereby the component (A) is distributed in the matrix X at appropriate intervals. As a result, uniformity of the electric characteristics is provided, and at the same time, the change in the volume resistivity and the like due to temperature is reduced. In addition, since the component (B) surrounding the component (A) is hydrophobically treated with the titanate-based coupling agent and the fatty acid-based compound as described above,
Resistance due to humidity change, particularly change in surface resistance, is also reduced.

FIG. 3 shows another example of the developing roll 3 incorporating the sleeve obtained by using the above semiconductive polymer material composition. That is, the developing roll 3 has a metal end cap 10 provided with a cylindrical metal core 11 made of a metal such as stainless steel or aluminum on the outer circumference thereof, and the sleeve 9 mounted on the outer circumference thereof via a conductive adhesive layer 12. I have. Also in this example, the sleeve 9 is the same as the sleeve 9 shown in FIG.
The structure is the same as that described above, the electrical characteristics are stable, and the change in volume resistivity and the like due to temperature change is reduced.

 Next, examples will be described together with comparative examples.

[Examples 1, 2 and Comparative Examples] In order to obtain a semiconductive polymer material composition, the following first
The raw materials shown in the table were blended in the proportions shown in the table. Table 2 shows the proportions of the components (A) and (B) in the whole composition in this case. As the component (A), carbon powder having an average flow diameter of 0.05 μm was used. As the component (B), Example 1 was manufactured by Ajinomoto Co., Inc.
Using KRTTS (comprising isopropyl triisostearoyl titanate represented by the general formula (I)), Example 2 was also manufactured by Ajinomoto Co., Inc. (Pyrophosphate) ethylene titanate].

Next, using the above composition, a cylindrical sleeve was formed by extrusion molding, and a developing roll 3 as shown in FIG. 1 was manufactured using this. In this case, the degree of change in the volume resistivity VR and the surface resistance RS due to the uniformity of the electrical characteristics of the sleeve 9 and the temperature change and the degree of change in the volume resistivity VR and the surface resistance RS due to the humidity change were examined. In this measurement, the volume resistivity VR and the surface resistivity were measured at the center and both left and right ends of the sleeve 9, respectively.
The RS was examined and the maximum and minimum values are shown in Tables 3 and 4 below. Table 3 shows the temperature dependence of the RV and RS, and Table 4 shows the temperature dependence of the RV and RS.

As is clear from Tables 3 and 4,
Whereas VR and VS are scattered within the range of less than one digit in each part of the sleeve 9, the values of the comparative examples vary by as much as five or six digits, and the uniformity of the electrical characteristics is From this point, it can be seen that the example product is remarkably excellent. Also, as is clear from Table 3, the degree of change of the RV and RS is extremely small compared to the comparative example and is superior to the comparative example. Further, the degree of change in the temperature dependence of RV and RS is extremely small for the example product, while the comparative example shows a large change value.

The product in the above embodiment is a developing roll of an electrophotographic copying machine. However, the roll of the present invention is not limited to this, and can be applied to, for example, a printer of a word processor.

〔The invention's effect〕

As described above, the roll of the present invention distributes the good conductive material particles of the component (A) and the hydrophobically treated particles of the conductive zinc as the component (B) in a matrix made of an insulating polymer molding material. , Uniformity of electrical characteristics, and temperature,
The fluctuation range of the volume resistivity and the surface resistance due to the humidity change is extremely small. As a result, a high-quality copy image can be formed, and a full-color electrophotographic copying machine can be used.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention, FIG. 2 is an explanatory view of the distribution of components (A) and (B) in the sleeve, and FIG. 3 is a partial view of another developing roll. FIG. 4 is an explanatory view of the development by the conventional triboelectric charging method, and FIG. 5 is an illustration of the movement state of the ionic conductive material particles of the conventional semiconductive polymer material composition in which the ionic conductive material particles are distributed. Fig. 6
The figure is an explanatory view of a chain state of conductive material particles in a conventional example in which conductive material particles are distributed in a matrix. 3 ... Developing roll, 9 ... Sleeve, 10 ... End cap

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01B 1/20 H01B 1/20 Z

Claims (3)

(57) [Claims] A cylindrical sleeve and an end cap for covering left and right openings of the sleeve. The cylindrical sleeve uses an insulating polymer as a matrix, and contains the following components (A) and (B) in the matrix. A roll characterized by containing a component. (A) Good conductive material particles having a volume resistivity of 10 ^-6 to 10 ^-1 Ωcm. (B) Hydrophobized particles of conductive zinc having a volume resistivity of 10 ¹ to 10 ⁴ Ω · cm. 2. The composition according to claim 1, wherein the components (A) and (B) are mixed in the following proportions (% by weight).
Role of description. 30 ≦ A + B ≦ 80 A ≦ B 4 ≦ A ≦ 20 30 ≦ B ≦ 60 3. The component (B) obtained by subjecting conductive zinc particles to a surface treatment with a titanate coupling agent or a fatty acid compound.
Role of description.