JPH0819254B2 - Semi-conductive polymer material composition - Google Patents

Description

The present invention relates to a semiconductive polymer material composition used for a developing roll of an electrophotographic copying machine.

[Conventional technology]

There are a wet method and a dry method as a developing method in an electrophotographic copying machine. Recently, the drying method has become the mainstream from the viewpoint of image fixability as compared with the wet method.
As this type of 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. Then, 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 to the developing roll 3.
The toner is attached to the outer peripheral surface of the photosensitive drum 1 in a charged state, and is evenly spread by the layer forming blade 5 to fly to the electrostatic latent image on the photosensitive drum 1 by an electric attraction force to attach toner 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 triboelectric charging as described above, the electrical characteristics of the developing roll 3, particularly the volume specific resistance (RV) and surface resistance (RS) are uniform and change depending on temperature and humidity. Not 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 synthetic resin materials for forming a developing roll 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 the developing roll obtained by using the former synthetic resin material, as shown in FIG. 5, when the temperature changes, the ionic conductive material particles Y dispersed in the matrix X move as shown by arrows. . In this way, when the ionic conductive material particles Y move, the volume resistivity and surface resistance of the developing roll change, and as a result, the temperature dependence of those resistances becomes large, and electrophotographic copying using it. In the machine, there is a problem in that the quality of the copied image depends on the temperature. Moreover, the above-mentioned problems also occur due to 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 the volume resistivity and the like slightly vary depending on the filling state of carbon, metal powder, etc., it is extremely difficult to control them and set the developing roll to a predetermined volume resistivity in the 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 and the like due to the chain state of the conductive material particles Y will be described in more detail. When there are many modes in which the conductive material particles Y are connected in a chain in the matrix X as in the central portion of FIG. When the conductive material particles Y are arranged in the small voids shown by the arrows on the right side of the drawing, the specific resistance and the like are reduced, and a tunnel effect occurs between them, which causes a reduction in the volume specific resistance and the like. It is substantially impossible to optimize the conductive material particles Y in such a state, and inevitably variations in volume resistivity and the like occur.

The present invention has been made in view of such circumstances,
An object of the present invention is to provide a semiconductive polymer material composition which has uniformity in volume resistivity and the like and which can form a developing roll or the like in which variation in volume resistivity due to temperature and humidity is small.

[Means for solving problems]

In order to achieve the above object, the semiconductive polymer material composition of the present invention is such that the insulating polymer molding material contains the following components (A) and (B) to impart semiconductivity. It is configured to be.

(A) A good conductive material powder 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.

That is, the inventors of the present invention have conducted researches focusing on the improvement of the latter two types of conventional synthetic resin materials for forming a developing roll, that is, those in which carbon, metal powder or the like is dispersed in a polymer matrix. As a result, when both the material conductive material powder having a specific volume specific resistance and the particles subjected to the hydrophobic treatment of conductive zinc having a lower conductivity than that are contained in the insulating polymer molding material, The inventors have found that the variation in the chain state or the dispersed state is small, the control to a predetermined semiconductivity is easy, and the change in the volume resistivity or the like due to temperature and humidity is small, and the present invention has been reached.

The semiconductive polymer material composition of the present invention comprises an insulating polymer molding material, a volume resistivity of 10 ⁻⁶ to 10 ⁻¹ Ω · cm, and a good conductive material powder, and a volume resistivity of 10 ¹ to 10 ^4. It is obtained using hydrophobic treated particles of conductive zinc of Ω · cm.

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.

As 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, carbon powder, graphite powder, titanium carbide powder, Examples thereof include metal powders, which may be used alone or in combination. Such a good conductive material powder has a particle size of 1 μm.
The following is preferable in terms of effects.

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 obtained by subjecting zinc oxide powder to a treatment agent mainly composed of aluminum and stirring and heat-treating it to conductive ZnO, which was subjected to surface treatment with a titanate coupling agent or a fatty acid compound. It is preferable that the particle size is about 0.1 to 3 μm in terms of the effect. Here, the electroconductive ZnO is ZnO treated with Al, and Al is coordinated to the lattice defects 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 represented by the following general formula (V) Tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate represented by the following general formula (VI) Examples thereof include bis (dioctylpyrophosphate) oxyacetate titanate represented by the following general formula (VII).

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

Further, instead of the titanate coupling agent, when the surface treatment with a fatty acid compound, stearic acid, fatty acids such as stearic acid metal salts or fatty acid metal salts, dissolved in an organic solvent to dissolve it, Similar to the above, it can be performed by dipping, spraying, and then drying. By surface-treating the conductive ZnO in this way, 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 components (A) and (B) are usually contained in the following proportions (% by weight) in the entire semiconductive polymer material composition. Be compounded.

30 ≤ A + B ≤ 80 A ≤ B 0 ≤ A ≤ 20 30 ≤ B ≤ 60 That is, by setting the ratio of the component (A) and the component (B) as described above, it is possible to use, for example, a developing roll. And the like, the volume resistivity of the roll or the like falls within a semiconductive range of about 10 ⁶ to 10 ¹² Ω · cm. Preferably, the resistance is set within a range of 10 ⁸ to 10 ¹¹ Ω · cm.

The semiconductive polymer material composition of the present invention comprises a thermosetting synthetic resin and a thermoplastic synthetic resin molding material that can be a polymer matrix, and the components (A) and (B) are mixed and mixed in the above proportions. It can be obtained by

A cylindrical article formed by extrusion molding, injection molding, compression molding or the like of the semiconductive polymer material composition thus obtained (for example, one using a novolak type phenol resin as an insulating polymer molding material) FIG. 1 shows a developing roll 3 in which is used as a sleeve of the developing roll. In the figure,
Reference numeral 9 is a sleeve formed by extrusion molding a semiconductive polymer material composition, and 10 is a metal end cap. In the developing roll 3, since the sleeve 9 is formed of the above semiconductive polymer material composition, the developing roll 3 has uniform electric characteristics (volume specific resistance and surface resistance), and moreover, due to temperature change and humidity change, Volume resistivity etc. does not change. 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 the figure, the micelles of the component (A) are surrounded by the particles of the component (B), so that the components (A) are distributed in the matrix X at appropriate intervals.
As a result, the electrical characteristics become uniform, and at the same time, the change in volume resistivity or the like due to temperature becomes small. Moreover, since the component (B) surrounding the component (A) has been subjected to the hydrophobic treatment with the titanate coupling agent and the fatty acid compound as described above, the resistance, especially the surface resistance change due to the humidity change can be also improved. Get smaller.

FIG. 3 shows another example of the developing roll 3 incorporating the sleeve obtained by using the above semiconductive polymer material composition. That is, in the developing roll 3, a metal-made end cap 1 is provided with a cylindrical core metal 11 made of metal such as stainless steel or aluminum, and the sleeve 9 is attached to the outer circumference thereof with a conductive adhesive layer 12 interposed therebetween. There is. Also in this example, the sleeve 9 is the sleeve 9 of 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 particle size of 0.05 μm was used, and as the component (B), Example 1 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 uniformity of the electrical characteristics of the sleeve 9 and the volume resistivity VR due to temperature changes
Moreover, the degree of change of the surface resistance RS and the degree of change of the volume resistivity VR and the surface resistance RS due to the change of humidity were also examined. In this measurement, the volume resistivity VR and the surface resistance RS of the central portion and the left and right end portions of the sleeve 9 are examined, and the maximum value and the minimum value thereof are shown in Tables 3 and 4 below. Table 3 shows the temperature dependence of the above RV and RS, and Table 4 shows the humidity dependence of the above RV and RS.

As is clear from Tables 3 and 4, the example products
While VR and VS remain within the range of change within 1 digit in each part of the sleeve 9, the value of the comparative example product varies by 5 digits or 6 digits, and in terms of uniformity of electrical characteristics. It can be seen that the example products are 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, regarding the humidity dependence of RV and RS, the degree of change of the example product is extremely small, while the comparative example product shows a large change value.

In the above example, the developing roll of an electrophotographic copying machine is manufactured using the semiconductive polymer material composition of the present invention, but the composition of the present invention is not limited to the above.
For example, it can be applied to a printer of a word processor.

〔The invention's effect〕

As described above, the semiconductive polymer material composition of the present invention contains both conductive material powders of the component (A) and the hydrophobic treated particles of conductive zinc of the component (B) in the insulating polymer molding material. Therefore, for example, in the case of manufacturing a sleeve of a developing roll or the like using this, it has a uniform electric characteristic,
Moreover, it is possible to manufacture a product in which the fluctuation range of volume resistivity and surface resistance due to temperature and humidity changes is extremely small. As a result, a high quality copy image can be formed, and
It will also be compatible with full-color electrophotographic copying machines.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a developing roll using a sleeve made of a semiconductive polymer material composition of the present invention, and FIG. 2 is an explanatory view of a distribution mode of components (A) and (B) in the sleeve. FIG. 3 is a partial sectional view of another developing roll, FIG. 4 is an explanatory view of development by a conventional triboelectric charging method, and FIG. 5 is a conventional semiconductive polymer material composition in which ionic conductive material particles are distributed. FIG. 6 is an explanatory view of a moving state of ionic conductive material particles of an object, and FIG. 6 is an explanatory view of a chained 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

Claims (3)

[Claims] 1. An insulating polymer molding material containing the following (A)
A semiconductive polymer material composition comprising a component and component (B) to impart semiconductivity. (A) A good conductive material powder 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 component (A) and the component (B) are blended in the whole in the following proportions (% by weight).
The semiconductive polymer material composition described. 30 ≦ A + B ≦ 80 A ≦ B 0 ≦ A ≦ 20 30 ≦ B ≦ 60 3. The semiconductive polymer material composition according to claim 1, wherein the hydrophobic treatment of the component (B) is a surface treatment with a titanate coupling agent or a fatty acid compound.