JPH0819262B2 - Conductive resin composition - Google Patents

Description

The present invention relates to a conductive resin composition used for a conductive roll such as a developing roll of an electrophotographic copying machine.

[Conventional technology]

Among the electrically conductive rolls that have been conventionally used, there are two types of synthetic resin materials for forming electronically conductive type rolls.
There are various types. One is a type in which a conductive polymer material is used as a synthetic resin material, and the resin matrix component itself has conductivity. But,
The above-mentioned type has a problem of lacking reliability such as durability, and it is the fact that it has not been generalized yet. The other type is an insulating polymer material in which conductive material particles are dispersed in the matrix component together with glass fiber and asbestos as a reinforcing agent. When a developing roll is formed using such a resin composition, it is required that the developing roll has a uniform volume resistivity (Rv) and is stable over time. This is to meet the demand for higher image quality and higher functionality of the copied image of the electrophotographic copying machine. In this case, in order to obtain the uniformity of the volume resistivity, various measures have been taken such that the respective materials of the resin composition are made to have a predetermined particle size, sufficiently mixed and uniformly dispersed.

[Problems to be solved by the invention]

However, the resin composition in which glass fiber and asbestos are blended as a reinforcing material in the above-mentioned insulating polymer material, even if each component is uniformly dispersed in the stage of the raw material, is cured through the molding process to form a molded article. Then, there is a big problem that the volume resistivity (Rv) of the molded product (cured product) deviates from the initial setting value with the passage of time.
In addition, since the degree of deviation of the volume resistivity varies depending on the part of the molded product, there is a problem that the volume resistivity partially varies. Therefore, it is extremely difficult to form a roll using such a resin composition and set the volume resistivity thereof to a predetermined value without partial variation.

The present invention has been made in view of such circumstances,
An object of the present invention is to provide a conductive resin composition capable of forming a cured body having a uniform volume resistivity and a value that does not change with time.

[Means for solving problems]

In order to achieve the above-mentioned object, the conductive resin composition of the present invention comprises a conductive agent and the following (A) in an insulating polymer material.
-(C) component is the following formula (I)-(IV) in the whole composition.
The composition is such that the content (% by weight) satisfies the above condition.

(A) Diameter d is 5 μm ≦ d ≦ 100 μm and length l is 1
Fibrous reinforcing material with mm ≦ l ≦ 12 mm.

(B) The diameter d is 0.1 μm ≦ d ≦ 10 μm, and the length l is
Fibrous reinforcing material with 0.5 μm ≦ l ≦ 100 μm.

(C) Diameter d is 0.01 μm ≦ d ≦ 0.1 μm and length l
Is a fibrous reinforcing material with 0.1 μm ≦ l ≦ 100 μm.

5 ≦ A ≦ 45 (I) 2 ≦ B ≦ 35 (II) 0 ≦ C ≦ 15 (III) 15 ≦ A + B + C ≦ 55 (IV) [Function] That is, the present inventors Among the two types of roll-forming composition, in view of its excellent durability, etc., the latter type of insulating polymer matrix is mixed with conductive agent particles such as carbon and metal powder. Focusing on what was done, we conducted repeated studies for the purpose of preventing the time-dependent change and partial variation in the volume resistivity (Rv) of the cured body. In the process of that research,
The present inventors have conceived that the time-dependent change in the volume resistivity, etc. may be influenced by a reinforcing material such as glass fiber among the various materials described above, and further focusing on the reinforcing material used. Repeated research. As a result, it was found that when three types of reinforcing materials with different dimensions were used and the mutual usage ratio was set within a specific range, the volume resistivity (Rv) did not change with time or partially. This invention was reached.

The conductive resin composition of the present invention is an insulating polymer material, a conductive agent, a specific fibrous filler (component A), and a specific fibrous filler (component B) having a smaller shape dimension than the component A.
And a specific fibrous filler (C component) having a smaller shape and dimension than the B component.

The insulating polymer material is not particularly limited. For example, it can be appropriately selected from thermosetting resins such as phenol resin, epoxy resin and unsaturated polyester resin, and thermoplastic resins such as vinyl chloride resin. In particular, from the viewpoint of volume resistivity and strength of the developing roll and the like, using a phenol resin brings good results.

The conductive agent dispersed in the insulating polymer material is not particularly limited, and examples thereof include carbon powder,
Graphite powder, titanium carbide powder, metal powder,
Examples include potassium titanate whisker reduction treated products, conductive treated zinc oxide powder, and tin oxide doped with antimony trioxide. These may be used alone or in combination. From the viewpoint of the effect, it is preferable that the conductive agent particles have a particle diameter in the range of about 0.01 to 3 μm.

The mixing ratio of the insulating polymer material and the conductive agent particles is such that the conductive material particles are 20 to 300 with respect to 100 parts by weight of the insulating polymer material.
It is preferable to set it within the range of parts by weight.

The first fibrous reinforcing material (A component) among the three kinds of reinforcing materials mixed in the insulating polymer material has a diameter d of 5 ≦.
d ≦ 100 μm and the length l must be in the range of 1 ≦ l ≦ 12 mm. However, the material is not particularly limited as long as it has the above-mentioned shape dimension. However, it is preferred to use glass fibers.

The second fibrous reinforcing material (component B) used together with the component A must have a diameter d of 0.1 ≦ d ≦ 10 μm and a length l of 0.5 ≦ l ≦ 100 μm. Any material having such a shape and dimension can be used. However, specific examples thereof include potassium titanate whiskers, silicon carbide whiskers, and silicon nitride whiskers, boron carbide whiskers, alumina whiskers, beryllium oxide whiskers, and the like which have the above-mentioned shape and dimensions.

In addition, the third component having a smaller shape and dimension than the B component described above.
As the fibrous reinforcing material (component C), the diameter d is 0.01 ≦ d
Examples thereof include ≦ 0.1 μm and length l in the range of 0.1 ≦ l ≦ 100 μm, and specific examples include asbestos, sepiolite, cloth chips, cellulose, wood flour and the like.

The above-mentioned A component, B component and the fibrous filler of the component may be used as they are, but it is more effective if they are treated with an interface coupling agent or the like suitable for the insulating polymer material used.

Moreover, the compounding quantity (weight%) of A component, B component, and C component in a conductive resin composition is the following formula (I)-(I.
It is necessary to set within the range that satisfies V).

5 ≦ A ≦ 45 (I) 2 ≦ B ≦ 35 (II) 0 ≦ C ≦ 15 (III) 15 ≦ A + B + C ≦ 55 (IV) The conductive resin composition of the present invention may include, for example, the above components. It is manufactured using the raw materials as follows. That is,
A thermosetting resin or a thermoplastic resin material that can be a polymer matrix is mixed with the above conductive agent particles, and
It can be obtained by mixing the components, the B component and the C component in the above proportions and mixing them sufficiently.

The conductive resin composition thus obtained (for example,
(Using a phenol resin as an insulating polymer material)
A developing roll 3 in which a cylindrical product formed by extrusion molding, injection molding or the like is used as a sleeve of the developing roll is shown in the figure. That is, the developing roll 3 is provided with a metal end cap 10
A cylindrical cored bar 11 made of metal such as stainless steel or aluminum is provided on the outer periphery of the sleeve, and a sleeve 9 formed by extrusion molding the conductive resin composition of the present invention on the outer periphery of the cylindrical cored bar 11 has a conductive adhesive layer 12 It is configured to be attached via. In the developing roll 3, since the sleeve 9 is formed of the conductive resin composition, the electrical characteristics (volume specific resistance and surface resistance) are uniform, and the characteristics do not change due to changes over time. This is considered to be due to the following reasons. That is, as the constituent material of the semiconductive resin composition, the conductive agent particles, the A
When the components B, C, and C are used, for example, in a matrix made of resin, the component A (glass fiber, etc.) and the component C (asbestos, etc.) having a considerably smaller shape size (diameter, length) than that are used. Since the B component having a shape and size intermediate between the two is mixed and dispersed, the above A component, B component and C component do not move in the matrix even if the environmental temperature changes. It is considered that the change in the arrangement state of the conductive agent particles does not occur.

 Next, examples will be described together with comparative examples.

[Examples 1 to 7, Comparative Example] The raw materials shown in Table 1 below were mixed in the proportions shown in the same table,
The desired conductive resin composition was obtained by mixing, kneading, cooling and pulverizing. Fibrous filler (A) in this case
The proportion of the component (C) in the entire composition is shown in Table 2.

Next, using the above composition, a cylindrical sleeve was formed by extrusion molding, and this was used to manufacture a developing roll as shown in the figure. In this case, the uniformity of the electrical characteristics of the sleeve and the degree of change in volume resistivity (Rv) with time were examined. This measurement is made on the 1st day, 10th day, 20th day, 3rd day after molding at 3 points on the center and left and right ends of the sleeve.
The volume resistivity (Rv) was examined on day 0, and the value is shown in Table 3 below.

As is clear from the above results, the volume resistivity (Rv) of the example product remains within the range of change within one digit in each part of the sleeve, whereas the value of the comparison product varies by two digits. In other words, it can be seen that the example products are remarkably excellent in terms of uniformity of electric characteristics. Further, even with the passage of time, the degree of change in volume resistivity (Rv) of the example product is extremely small even after 30 days from the molding, while the comparative example product shows a large change value.

In the above examples, the semiconductive resin composition of the present invention is used to manufacture a developing roll for an electrophotographic copying machine. However, the composition of the present invention is not limited to the one described above, and may be, for example, a word processor. It can also be applied to a printer of a processor.

〔The invention's effect〕

As described above, the semiconductive resin composition of the present invention specifies the above-mentioned A component, the C component having a smaller shape size (diameter, length) than the A component, and the B component having a shape intermediate between them. Since it is contained in the insulating polymer material within the range,
Changes in the volume resistivity of the cured product over time and partial variations do not occur. Therefore, when using this semiconductive resin composition to form a cylindrical sleeve such as a developing roll, for example, the sleeve has uniform electrical characteristics in the sleeve and has a fluctuation range of the volume resistivity (Rv). Very small ones can be manufactured. As a result, it is possible to form a high quality copy image, and it is also possible to cope with higher functionality of the electrophotographic copying machine.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a developing roll using a sleeve made of a conductive resin composition of the present invention.

Claims (1)

[Claims] 1. A conductive agent and the following components (A) to (C) in an insulating polymer material are represented by the following formulas (I) to (I) in the entire composition.
A conductive resin composition, characterized in that the conductive resin composition is contained in a proportion (% by weight) that satisfies (IV). (A) Diameter d is 5 μm ≦ d ≦ 100 μm and length l is 1
Fibrous reinforcing material with mm ≦ l ≦ 12 mm. (B) The diameter d is 0.1 μm ≦ d ≦ 10 μm, and the length l is
Fibrous reinforcing material with 0.5 μm ≦ l ≦ 100 μm. (C) Diameter d is 0.01 μm ≦ d ≦ 0.1 μm and length l
Is a fibrous reinforcing material with 0.1 μm ≦ l ≦ 100 μm. 5 ≦ A ≦ 45 (I) 2 ≦ B ≦ 35 (II) 0 ≦ C ≦ 15 (III) 15 ≦ A + B + C ≦ 55 (IV)