JPH0990737A - Roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll excellent in toner separability. SOLUTION: The outermost layer 13 of a roll is formed by using the following (A) rubber composition. (A) In a rubber composition by dispersing particles formed of a die separable agent in this fluororubber matrix by using fluororubber as a matrix component, the die separable agent is at least one of reactive silicone oil and reactive fluorine oil, and particles formed of the die separable agent are reactively fixed in the fluororubber matrix, and the cross-sectional areas of particles whose particle diameter is not less than 0.1μm are measured, and when these are accumulated in order from small one, the rubber composition is set so that a particle diameter of particles at a point becoming the accumulative cross-sectional area of a rate of 90% becomes equal to smaller than 30μm to this overall accumulative cross-sectional area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll such as a developing roll and a fixing roll that comes into contact with toner, and more particularly to a roll having an outermost layer having excellent toner releasability. Is.

[0002]

2. Description of the Related Art In an electrophotographic copying machine or the like, for a roll which comes into contact with toner, such as a developing roll, it is required to prevent the toner from adhering to the roll surface as an important characteristic. Therefore, the outermost layer of such a roll is formed by using a fluororubber composition having excellent mold releasability, and in order to further improve the releasability, the fluororubber composition has a release agent. Contains silicone oil.

[0003]

However, since the fluororubber and the silicone oil have poor compatibility, the silicone oil may be present in the fluororubber matrix in the form of large aggregates. In such a state, for example, in the developing roll of an electrophotographic copying machine, the supply of silicone oil to the roll surface becomes uneven,
As a result, toner adheres to the portion where the silicone oil is deficient, and this causes the toner to spread further, and eventually toner filming occurs.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a roll having an outermost layer excellent in toner releasability.

[0005]

In order to achieve the above-mentioned object, the roll of the present invention is a roll having one or two or more layers formed on the outer periphery of a shaft body. The outermost layer is formed of the rubber composition (A) below. (A) A rubber composition in which fluororubber is used as a matrix component, and particles formed from a release agent are dispersed in the fluororubber matrix, wherein the release agent is at least reactive silicone oil and reactive fluorine oil. On the other hand, the particles formed from the release agent are reactively fixed in the fluororubber matrix, and the cross-sectional area of the particles having a particle size of 0.1 μm or more is measured. A rubber composition in which, when accumulated, the particle diameter of the particles at the point where the cumulative cross-sectional area is 90% of the total cumulative cross-sectional area is 30 μm or less.

Here, "the particles are reactively fixed" means
It means that the fluororubber molecules forming the matrix react with the reactive silicone oil or the like forming the particles, and the two are chemically bonded and fixed. It is not necessary that all reactive silicone oils, etc. chemically bond with the fluororubber, and if the reactive silicone oil, etc. mainly located on the surface of the particles chemically bond, the release agent particles will be reactively fixed in the fluororubber matrix. Is done. Further, in the rubber composition used for forming the outermost layer of the roll of the present invention, the fluororubber matrix includes both a state in which the fluororubber molecules are not crosslinked and a state in which they are crosslinked by vulcanization. However, it goes without saying that the rubber composition is vulcanized after the outermost layer of the roll is formed.

Further, "when the cross-sectional area of the above-mentioned particles having a particle diameter of 0.1 μm or more is measured and these are sequentially accumulated from the smallest one" means the following case. That is, in the fluororubber composition, the particle size distributed in this is 0.1 μm.
The cross-sectional area of the above particles is measured. The particle size refers to the maximum particle size of the particles. For example, when the cross-sectional shape of the particles is circular, the diameter is the particle diameter, and when the cross-sectional shape of the particles is elliptical, the major axis is the particle diameter. Further, the above-mentioned measurement can be performed by observing the fluororubber composition with a scanning electron microscope, for example. This observation is
It is not necessary to carry out the entire rubber composition, and it may be carried out partially by deciding an observation site (sampling site). The sampling points are preferably 4 to 30 points, particularly preferably 20 to 30 points. Further, the calculation of the cross-sectional area is performed according to the cross-sectional shape of the particles, for example,
The particle cross section can be obtained by dividing the particle cross section into small areas, calculating the area of each part, and summing the areas. Then, this cross-sectional area is sequentially accumulated from the smallest one, and the total cumulative cross-sectional area is calculated.

Then, "90 for this total cumulative cross-sectional area
The particle size at the point where the cumulative cross-sectional area in% is 30 μm
“Below” means the following. That is, the cumulative cross-sectional area of 90% of the total cumulative cross-sectional area is derived. Then, the particle size of particles at the point where the cumulative cross-sectional area is 90% (hereinafter referred to as "90% cumulative cross-sectional area particle size") is obtained. An example of this is shown in the graph of FIG. In this graph, the vertical axis is the cumulative cross-sectional area ratio (%), and the horizontal axis is the particle size (μm) and the particle cross-sectional area (μm ² ). As shown in the figure, when particles are sequentially accumulated from the one having a small cross-sectional area, a curve is obtained in which the cumulative cross-sectional area ratio increases as the particle diameter (cross-sectional area) increases. Then, as indicated by the dotted line, the particle size of the particles at the point corresponding to the 90% cumulative cross-sectional area is obtained. If the particle size of the particles at this point is 30 μm or less, the requirements of the present invention are satisfied.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the roll of the present invention is characterized by using a special rubber composition in the outermost layer. At least one of a reactive silicone oil and a reactive fluorine oil is blended as a release agent in this special fluororubber composition, and particles of the release agent are reactively fixed in the fluororubber matrix. This state is shown in the schematic diagram of FIG. 1. In the fluororubber matrix 1, particles 2 formed of a reactive silicone oil or the like react with the fluororubber molecule 1a and are chemically bonded. This chemical bond differs depending on the type of reactive group such as reactive silicone oil. And
As described above, in the particle size distribution of the particles 2, the 90% cumulative cross-sectional area particle size is set to 30 μm or less, and the particles 2 are uniformly dispersed. Further, also in the outermost layer of the roll formed by using such a special rubber composition, the particles of the release agent are in a state of being uniformly fixed and reactively fixed. Therefore, for example, in a roll having the outermost layer formed by using this rubber composition, the reactive silicone oil or the like, which is a release agent, does not exude into a large aggregate. As a result, for example, when the roll of the present invention is applied to a developing roll, high toner releasability is maintained for a long period of time, and toner filming is prevented from occurring.

Next, the present invention will be described in detail.

As the roll of the present invention, for example, as shown in FIG. 6, an innermost layer 11 is formed along the outer periphery of a shaft body 10, an intermediate layer 12 is formed on the outer peripheral surface thereof, and further on the outer peripheral surface thereof. An example is a structure having the outermost layer 13 formed.

As the shaft body 10, any conventionally known shaft body may be used. For example, a metal core made of a solid metal body, a metal cylindrical body having a hollow inside, or the like is used. Then, examples of the material thereof include aluminum, stainless steel and the like.

The material for forming the innermost layer 11 formed on the outer periphery of the shaft body 10 and the intermediate layer 12 formed on the outer peripheral surface thereof is not particularly limited, and any conventionally known material may be used. Good. For example, as a forming material of the innermost layer 11, ethylene-propylene rubber (EPD
M), styrene-butadiene rubber (SBR), silicone rubber, polyurethane elastomer, and the like mixed with carbon black. Examples of the material for forming the intermediate layer 12 include EPDM, SBR, nitrile rubber, hydrogenated nitrile rubber, polyurethane elastomer, polyester, N-methoxymethylated nylon, carbon black, metal oxide, quaternary ammonium salt, and the like. The one containing the conductive agent is mentioned. A conventionally known method is also applied to the method of preparing the materials for forming the innermost layer 11 and the intermediate layer 12. To give an example of this,
The forming material (compound form) of the innermost layer 11 can be prepared by kneading the above-mentioned components with a kneader such as a kneader. The material (coating liquid) for forming the intermediate layer 12 can be prepared by kneading the above components with a ball mill, a roll, or the like, adding a solvent to the mixture, and stirring the mixture.

The outermost layer 13 formed on the outer peripheral surface of the intermediate layer 12 contains a special fluororubber and at least one of reactive silicone oil (component A) and reactive fluorooil (component B). It is formed using a rubber composition.

The above-mentioned fluororubber is not particularly limited, and conventionally known ones can be used. However, tetrafluoroethylene-polypropylene (TFE-PP) is used because of its low polymer viscosity and good filler dispersibility. ) It is preferable to use a copolymer, and it is particularly preferable to use a random copolymer having a structure represented by the following general formula (1).

[0016]

Embedded image

In the above formula (1), the ratio of each repeating portion m, n, p is a weight ratio of m: n: p = (30 to
60) :( 10-40): It is preferable to use those set to (10-40), and particularly preferably, m:
n: p = (30 to 50) :( 30 to 40) :( 20 to 3)
0).

Next, the reactive silicone oil (component A) and the reactive fluorine oil (component B) blended in the fluororubber are toner release agents, and are blended with both component A and component B. Alternatively, either one of the above two components may be blended alone.

Both the reactive silicone oil (component A) and the reactive fluorine oil (component B) are at least selected from the group consisting of hydroxyl group, amino group, mercapto group, epoxy group, carboxyl group and methacryl group. Those having one reactive group are preferred. These reactive groups react with the fluororubber, whereby the particles formed from the oil are fixed in the fluororubber matrix. This reaction fixation (chemical bond)
The mode of is shown below for each reactive group.

[Hydroxyl group]

Embedded image

[Amino group]

Embedded image

[Mercapto group]

Embedded image

[Epoxy group]

Embedded image

[Carboxyl group]

[Chemical 6]

[Methacrylic group]

[Chemical 7]

These reactive groups are located at the ends (including both ends) of the molecular chain and the side chains, and differ depending on the type of oil and the like.

Among the above-mentioned reactive groups, a hydroxyl group, an amino group and a mercapto group are preferable because of their good reactivity with fluororubber, and an amino group is particularly preferable. For thermal stability, the reactive silicone oil (A component) preferably has an average molecular weight of 300 or more, and the reactive fluorine oil (B component) preferably has an average molecular weight of 200 or more, particularly preferably both. Is 1
It is 500 to 20,000. Furthermore, these reactive silicone oil (A component) and reactive fluorine oil (B
The total compounding ratio (A + B) of the components) is 100
It is preferably in the range of 0.5 to 100 parts, and particularly preferably in the range of 15 to 50 parts, relative to parts by weight (hereinafter abbreviated as "part").

Specific examples of such reactive silicone oil (component A) and reactive fluorine oil (component B) are shown below.

[Reactive Silicone Oil Having Hydroxyl Group]

Embedded image

[Reactive Silicone Oil Having Amino Group]

Embedded image

[Reactive Silicone Oil Having Mercapto Group]

Embedded image

[Reactive Silicone Oil Having Epoxy Group]

Embedded image

[Reactive Silicone Oil Having Carboxyl Group]

[Chemical 12]

[Reactive Silicone Oil Having Methacrylic Group]

Embedded image

[Reactive Fluorine Oil Having Hydroxyl Group]

Embedded image

[Reactive Fluorine Oil Having Amino Group]

[Chemical 15]

[Reactive Fluorine Oil Having Mercapto Group]

Embedded image

[Reactive Fluorine Oil Having Epoxy Group]

Embedded image

[Reactive Fluorine Oil Having Carboxyl Group]

Embedded image

[Reactive Fluorine Oil Having Methacrylic Group]

Embedded image

Among the reactive silicone oils (component A) and reactive fluorine oils (component B) shown in the above specific examples, those having a hydroxyl group, an amino group or a mercapto group are preferable from the viewpoint of reactivity. Yes, and particularly preferred is one having an amino group.

Next, in the rubber composition used in the present invention,
In addition to the above-mentioned reactive silicone oil (component A) and reactive fluorine oil (component B), non-reactive silicone oil (component C) and non-reactive fluorine oil (component D) can be blended. These non-reactive silicone oils and non-reactive fluoro oils do not have a reactive group for reaction fixation in the fluoro rubber matrix, but when used in combination with the above reactive silicone oils, etc. Fixed. This is because non-reactive silicone oil etc. are mixed in particles formed from reactive silicone oil etc. and both are bonded by a hydrophobic bond, and as a result, non-reactive silicone oil etc. is fixed in the fluororubber matrix. It is presumed that it will be done. Therefore,
Even if a non-reactive silicone oil or the like is used, if it is a predetermined amount, there is no possibility that large agglomerates thereof will be generated.

The above non-reactive silicone oil (component C)
Is preferably one having at least one organic group selected from the group consisting of an alkyl group, an aralkyl group, a higher alcohol ester group, and a polyether fluoroalkyl group. This is because these are highly effective as a release agent.

Among the above-mentioned non-reactive silicone oils, those having an average molecular weight of 500 to 100,000 are preferable, and particularly preferable are those having an average molecular weight of 2,000 to 50,000, because of their high releasability and thermal stability. It is in the range of.

The blending ratio of the non-reactive silicone oil is usually 10 to 1 per 100 parts of fluororubber.
It is set in the range of 00 parts, preferably in the range of 20 to 50 parts, particularly preferably in the range of 30 to 40 parts.

Specific examples of such a non-reactive silicone oil are shown below.

[Non-Reactive Silicone Oil Having Alkyl Group]

Embedded image

[Non-Reactive Silicone Oil Having Aralkyl Group]

[Chemical 21]

[Non-Reactive Silicone Oil Having Higher Alcohol Ester Group]

Embedded image

[Non-Reactive Silicone Oil Having Polyether Fluoroalkyl Group]

Embedded image

Among the non-reactive silicone oils shown as these specific examples, because of its high releasability,
Those containing an alkyl group, a higher alcohol ester group, or a polyether fluoroalkyl group are preferably used, and those having a higher alcohol ester group are particularly preferable.

As the non-reactive fluorine oil (component D), perfluoropolyether or the like is used.

The rubber composition used in the present invention contains
In addition to the above-mentioned reactive silicone oil (A component), reactive fluorine oil (B component), non-reactive silicone oil (C component) and non-reactive fluorine oil (D component), an appropriate volume electric resistance (10 ⁷ An ionic conductive agent can be blended for the purpose of imparting 10 ¹² Ω · cm). The characteristic relating to the volume electric resistance is important as the characteristic of the outermost layer of the developing roll, for example.

Examples of the ionic conductive agent include trimethyl octadecyl ammonium chloride, benzyl trimethyl ammonium chloride, trioctyl propylene ammonium chloride, trioctyl propyl ammonium bromide, trimethyl octadecyl ammonium perchlorate, tetrabutyl ammonium hydrogen sulfate, tetrabutyl ammonium. Quaternary ammonium compounds such as hydroxide and perchlorates and benzoates of these quaternary ammonium compounds,
Examples thereof include nitrite, sulfate, and hydroxide. These may be used alone or in combination of two or more. Above all,
It is preferable to use tetrabutylammonium hydrogen sulfate (TBAHS) or tetrabutylammonium hydroxide.

In addition to the above ion conductive agents, acid acceptors such as calcium hydroxide, magnesium oxide, calcium oxide, red lead, litharge, etc., and vulcanizing agents such as peroxide, bisphenol A, bisphenol AF, hexamethylene diamine, etc. Can be appropriately blended as necessary. As will be described later, it is preferable that the vulcanizing agent be blended each time the rubber composition of the present invention is used (before coating).

Next, the rubber composition used in the present invention can be prepared by using the above-mentioned materials, for example, by the following method (first method).

That is, first, the fluororubber is kneaded in a closed kneader (for example, Banbury mixer). After adding an acid acceptor thereto and further kneading, at least one of reactive silicone oil (A component) and reactive fluorine oil (B component), and if necessary, non-reactive silicone oil (C component), non-reactive silicone oil Reactive fluorine oil (D component),
Add other ingredients and continue kneading. Then, after the torque of the kneader increases, the kneading is stopped and the kneaded product is taken out. Then, this kneaded product is sheeted with an open roll. Then, this is dissolved in a solvent to prepare a rubber composition (coating liquid). Examples of the solvent include ethyl acetate, methyl ethyl ketone, methanol,
Examples include toluene, isopropyl alcohol, methyl cellosolve, and dimethylformamide. These may be used alone or in combination of two or more. At this stage, it is preferable that the vulcanizing agent is not compounded but compounded before use (before coating).

Further, the above rubber composition can be prepared by the following method (second method) in addition to the above method.

That is, first, the fluororubber is dissolved in a solvent. Examples of the solvent include ethyl acetate, methyl ethyl ketone, methanol, toluene, isopropyl alcohol, methyl cellosolve, and dimethylformamide. These may be used alone or in combination of two or more. Then, at least one of the reactive silicone oil (component A) and the reactive fluorine oil (component B), and optionally a non-reactive silicone oil (component C) and a non-reactive fluorine oil, in the dissolved fluororubber. (D
Ingredients) and other ingredients. Then, stirring is performed under heating to increase the viscosity, and when the viscosity becomes constant, the stirring is stopped to prepare a rubber composition (coating liquid). The heating conditions are preferably in the range of 40 ° C or higher and not higher than the boiling point of the solvent, and particularly preferably in the range of 50 to 80 ° C. At the time of this adjustment, no vulcanizing agent was added,
It is preferable to mix before use (before coating). It is speculated that the increase in viscosity during stirring is due to the finer particles of the reactive silicone oil or the like (increasing the total surface area) and the chemical bonding between the reactive silicone oil and the fluororubber molecules. The constant viscosity is usually 2000 to 20000 cps, and preferably 3000 to 5000 cps, although it varies depending on the material used.

In the rubber composition thus obtained,
Particles formed of reactive silicone oil or the like (release agent) in the fluororubber matrix are uniformly dispersed with a 90% cumulative cross-sectional area particle size of 30 μm or less, and the fluororubber matrix ) Is immobilized by reaction (see FIG. 1). As a result, as mentioned above,
Releasability can be maintained for a long period of time without generation of large aggregates of reactive silicone oil or the like. The particle size of the particles is preferably 0.1 to 20 μm,
Particularly preferably, it is 0.1 to 5 μm.

Next, the roll of the present invention as shown in FIG. 6 is produced, for example, as follows.

That is, first, using the materials for forming the innermost layer 11 and the intermediate layer 12 prepared as described above, the innermost layer 11 and the intermediate layer 12 are formed in this order on the outer periphery of the shaft body 10 in this order according to a conventional method. Then, a roll substrate is prepared. For example, as shown in FIG. 7, the lower lid 15 on which the shaft body 10 is set
Then, a compound-like innermost layer forming material is cast into the cylindrical mold 16, and the upper lid 17 is fitted onto the cylindrical mold 16. In this state, the entire roll die is heated (vulcanization treatment, conditions: 150-
200 ° C. × 20 to 40 minutes) to form the innermost layer 11.
Then, the shaft body 10 on which the innermost layer 11 is formed is demolded, and the residue of the vulcanizing agent is removed by evaporation if necessary. Then, the intermediate layer forming material (coating liquid) is applied to the outer peripheral surface of the innermost layer 11 and dried and heat-treated (vulcanization treatment, condition: 120
To 200 ° C. for 10 to 30 minutes) to form the intermediate layer 12. For the coating, conventionally known coating methods such as a dipping method, a spray method and a roll coating method can be applied. In this way, the innermost layer 11 and the intermediate layer 12 are provided on the outer periphery of the shaft body 10.
A roll substrate on which is formed is prepared.

On the other hand, the rubber composition (coating liquid)
A vulcanizing agent is mixed with. Then, the rubber composition is applied to the outer peripheral surface of the intermediate layer 12 of the roll substrate. This coating method is not particularly limited, and a conventional method such as a dipping method, a spray method or a roll coating method can be applied. Then, after coating, drying and heat treatment (vulcanization treatment,
(Conditions: 150 to 200 ° C. × 20 to 40 minutes), the solvent in the rubber composition is removed by evaporation and the fluororubber component is crosslinked. In this way, a roll having a three-layer structure as shown in FIG. 6 can be manufactured. In addition, in this roll, the thickness of each layer is appropriately determined. For example, in the developing roll, the thickness of the innermost layer is 2 to 10
The thickness is preferably set in the range of mm, particularly preferably 3 to 6 mm. The thickness of the intermediate layer is 3 to 90.
The thickness is preferably set in the range of μm, and the particularly preferable thickness is 5 to 15 μm. And the thickness of the outermost layer is 2
0 to 100 μm is preferable, and 30 to 70 is particularly preferable.
μm.

The roll thus obtained is suitable for the developing roll, but is not necessarily limited to the developing roll. That is, the roll of the present invention is characterized in that the outermost layer thereof has excellent toner releasability for a long period of time. Therefore, as long as the roll surface (outermost layer) is of a type that directly contacts with the toner, It is also effective when applied to such rolls. Examples of such a roll include a fixing roll and the like. Further, as an example of the roll of the present invention, a roll having a three-layer structure is shown in FIG. 6, but the layer formed on the outer periphery of the shaft body 10 may not necessarily be a three-layer, and may be appropriately selected depending on the application of the roll. Layers are formed. However, the outermost layer (in the case of a single layer, the outermost layer) must be formed of the above-mentioned special rubber composition.

[0065]

As described above, in the roll of the present invention, the outermost layer thereof is formed of a special fluororubber composition. In this special fluororubber composition, particles formed of reactive silicone oil or the like are dispersed in a fluororubber matrix, the particle size distribution of the particles is 90%, and the cumulative cross-sectional area particle size is 30 μm or less, and The particles are reactively fixed in the fluororubber matrix. Therefore, it is possible to prevent the generation of large aggregates of silicone oil, which is a toner release agent, and the exudation onto the roll surface, which are problems in the outermost layer of the conventional developing roll. As a result, for example, if the roll of the present invention is used as a developing roll, toner filming is prevented from occurring and a good quality copy image can be obtained for a long period of time.

Next, examples will be described together with comparative examples.

First, prior to Examples and Comparative Examples, a core metal (diameter 10 mm, made of SUS304) to be a shaft, a liquid silicone rubber to which carbon black was added as an innermost layer forming material, and an intermediate layer forming material A product obtained by adding carbon black to hydrogenated nitrile rubber was prepared.

Then, according to the above-mentioned method, the innermost layer and the intermediate layer were formed on the outer periphery of the shaft body to prepare a roll substrate.

[0069]

Examples 1 to 7 and Comparative Examples 1 to 4 The outermost layer was formed on the outer peripheral surface of the roll substrate by the second method described above. That is, the materials shown in Tables 1 to 3 below were mixed in the proportions shown in the same table, and a fluororubber composition was prepared according to the second method described above. Then, using this fluororubber composition, the outermost layer was formed on the outer peripheral surface of the roll base by the above-mentioned method (coating method: roll coating method), and a desired developing roll was produced. The innermost layer of this developing roll has a thickness of 5 mm, the intermediate layer has a thickness of 10 μm, and the outermost layer has a thickness of 50 μm.

With respect to the developing rolls of Examples 1 to 7 and Comparative Examples 1 to 4 thus obtained, the evaluation of copied images and the occurrence of toner filming were examined by the following methods. The results are also shown in Tables 1 to 3 below. Further, in the same table, the average particle size of the particles and the 90% cumulative cross-sectional area particle size are also shown. The 90% cumulative cross-sectional area grain size was measured by the method described below.

[Evaluation of Copy Image] The developing roll was incorporated in an electrophotographic copying machine to actually perform copying. Then, the image quality of the copied image was visually evaluated at the initial stage of copying and after copying 30,000 sheets. That is, the characters are printed and there is no problem in the copied image,
The fine lines were clearly copied, and the fine lines and fogging were marked with x. It should be noted that the faint means that the fine line is broken, and the fog means that the toner is scattered in a place where there is no image. In addition, when toner filming occurred, evaluation was performed separately for a portion where toner filming occurred and a portion where toner filming did not occur.

[Toner Filming] In a portion where the toner thickly adheres to the surface of the developing roll, the charging property is deteriorated and a defective copy image occurs. Specifically, if a part of the toner component adheres to the surface of the developing roll with a thickness of 1 μm or more, the image is significantly deteriorated. Therefore, when the toner adhesion is 1 μm or more, the toner filming is considered to have occurred.

[90% cumulative cross-sectional area particle size] As shown in FIG. 9A, two breaks are formed in the elastic body portion (inner layer, intermediate layer, outermost layer) of the developing roll 20 at right angles to the axial direction. It was cut into slices, further cut in the axial direction, taken out from the core metal, and a sample 20a as shown in FIG. Then, as shown in the cross-sectional view of the sample 20a in the same figure (C), observation was performed with a scanning electron microscope (S-4100, manufactured by Horiba, Ltd.) at four locations (outermost layer portions) surrounded by dotted lines. . Then, the 90% cumulative cross-sectional area grain size was automatically determined by using the image processor (Spica II, manufactured by Nippon Avionics Co., Ltd.) according to the procedure described above.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

[Table 3]

From the above Tables 1 and 2, the developing rolls of Examples 1 to 7 in which the particles of reactive silicone oil or the like have a 90% cumulative cross-sectional area particle size of 30 μm or less have no problem in copied images, and Fine lines were clearly copied, and toner filming did not occur. On the other hand, from Table 3 above, in the developing rolls of Comparative Examples 1 to 4 in which the 90% cumulative cross-sectional area particle size of the particles of reactive silicone oil etc. exceeds 30 μm, toner filming occurs, and in this part, The copied image was bad.

Next, the state of the particles formed from the reactive silicone oil in the outermost layer of the developing rolls of Example 1 and Comparative Example 1 was examined using the scanning electron microscope, and the results are shown in FIGS. Shown in the photo.

FIG. 2 is a photograph showing the condition of the outermost layer surface of the developing roll of Example 1 (magnification: 10,000 times), and FIG. 3 is a photograph showing the condition of the inside of the same outermost layer (axial cross section) ( Magnification 1
10,000 times). FIG. 4 is a photograph (magnification: 10,000 times) showing the state of the outermost layer surface of the developing roll of Comparative Example 1.
Is a photograph (magnification: 10,000 times) showing a state inside the same outermost layer (cross section in the axial direction). From the photographs of FIGS. 2 and 3, in the developing roll of Example 1, the particles formed from the reactive silicone oil had a very small particle size of about 1 μm or less and were uniformly dispersed in the fluororubber matrix. I understand. On the other hand, from the photographs of FIGS. 4 and 5, it can be seen that in the developing roll of Comparative Example 1, the particle size of the particles formed from the reactive silicone oil is large.

Particles formed from the reactive silicone oil dispersed in the fluororubber matrix were comprehensively judged from the results of these electron microscope observations and the results (toner filming) of Tables 1 to 3 above. It can be said that toner filming was prevented in the developing roller of the example because the 90% cumulative cross-sectional area particle size of No. 3 was 30 μm or less and the particles were reactively fixed in the fluororubber matrix.

[Brief description of drawings]

FIG. 1 is a schematic view showing a microscopic structure of a rubber composition of the present invention.

FIG. 2 is a photograph showing the structure of particles formed from reactive silicone oil on the surface of the outermost layer of the developing roll that is an example of the present invention.

FIG. 3 is a photograph showing the structure of particles formed from a reactive silicone oil inside the outermost layer of the developing roll that is an example of the present invention.

FIG. 4 is a photograph showing the structure of particles formed from reactive silicone oil on the surface of the outermost layer of a conventional developing roll.

FIG. 5 is a photograph showing the structure of particles formed from a reactive silicone oil inside the outermost layer of a conventional developing roll.

FIG. 6 is a cross-sectional view showing the structure of a developing roll.

FIG. 7 is a cross-sectional view showing a method of manufacturing a developing roll.

FIG. 8 is a graph showing the relationship between the particle size of particles and the cumulative cross-sectional area ratio of particles.

9A is a perspective view showing a state in which a developing roll is cut, FIG. 9B is a perspective view of a sample cut out from the developing roll, and FIG. 9C is a sectional view of the sample. .

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 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akihiko Kaji 3600 Gyōtsu, Kotomaki, Koichi, Aichi Tokai Rubber Industry Co., Ltd.

Claims (6)

[Claims] 1. A roll in which one or more layers are formed on the outer periphery of a shaft body, and the outermost layer of these layers is formed of the rubber composition (A) below. Roll characterized by. (A) A rubber composition in which fluororubber is used as a matrix component, and particles formed from a release agent are dispersed in the fluororubber matrix, wherein the release agent is at least reactive silicone oil and reactive fluorine oil. On the other hand, the particles formed from the release agent are reactively fixed in the fluororubber matrix, and the cross-sectional area of the particles having a particle size of 0.1 μm or more is measured. A rubber composition in which, when accumulated, the particle diameter of the particles at the point where the cumulative cross-sectional area is 90% of the total cumulative cross-sectional area is 30 μm or less. 2. The reactive silicone oil is a reactive silicone oil having at least one reactive group selected from the group consisting of hydroxyl group, amino group, mercapto group, epoxy group, carboxyl group and methacryl group,
The roll according to claim 1, wherein the reactive fluorine oil has at least one reactive group selected from the group consisting of a hydroxyl group, an amino group, a mercapto group, an epoxy group, a carboxyl group and a methacryl group. 3. The roll according to claim 1, wherein the reactive silicone oil has an average molecular weight of 300 to 150,000 and the reactive fluorine oil has an average molecular weight of 200 to 20,000. 4. The total blending ratio of the reactive silicone oil and the reactive fluorine oil is such that the fluororubber 10
0.5 to 100 parts by weight with respect to 0 parts by weight.
The roll according to any one of to 3. 5. The roll according to claim 1, wherein the particles formed from the release agent contain at least one of non-reactive silicone oil and non-reactive fluorine oil. 6. The roll according to claim 5, wherein the non-reactive silicone oil has a higher alcohol ester group, and the non-reactive fluorine oil is perfluoropolyether.