JPH0995559A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber compsn. which is the most suitable for forming the outermost layer of a developing roll, etc., for preventing the occurrence of toner filming. SOLUTION: This compsn. 1 comprises a fluororubber matrix 1a and particles 2 dispersed therein and comprising at least either a reactive silicone oil or a reactive fluorine oil, subject to the conditions that the particles 2 are reacted with and fixed by the matrix 1a in the form of being partly connected to the matrix and that, when the cross-sections of particles having particle sizes of 0.1μm or higher are accumulated successively from the small sizes, the particle size at the point of 90% accumulation is 30μm or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition containing fluororubber as a base material, and more specifically, to a rubber composition most suitable for forming an outermost layer of a roll such as a developing roll which comes into contact with a toner. It is about things.

[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 with each other, the silicone oil may become large aggregates and may be unevenly present in the fluororubber matrix. In such a state, for example, in the developing roll of an electrophotographic copying machine, the silicone oil supplied to the roll surface becomes excessive and deficient, and as a result, toner adheres to the portion where the silicone oil is deficient, and this is the starting point. As a result, the toner adhesion further spreads, and finally toner filming occurs.

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

[0005]

In order to achieve the above object, the rubber composition of the present invention comprises a fluororubber as a matrix component, and at least a reactive silicone oil and a reactive fluorooil are contained in the fluororubber matrix. A rubber composition in which particles composed of one side are dispersed, wherein the particles are reactively fixed to the fluororubber matrix in a state where the particles are partially connected inside the fluororubber matrix, and the particle size of the particles is a particle size. When measuring the cross-sectional area of particles of 0.1 μm or more and sequentially accumulating them from the smallest one, set the particle size at the point where the cumulative cross-sectional area of 90% of this total cumulative cross-sectional area is 30 μm or less. It is configured to be.

Here, "the particles are reactively fixed to the fluororubber matrix" means that the fluororubber molecules constituting the matrix react with the reactive silicone oil or the like forming the particles to chemically bond them. It is fixed. It should be noted that not all reactive silicone oils or the like need to chemically bond with the fluororubber, and if reactive silicone oils or the like mainly located on the surface of the particles chemically bond,
The particles are reactively fixed to the fluororubber matrix. Further, the fluororubber matrix includes both a state in which fluororubber molecules are not crosslinked and a state in which they are crosslinked by vulcanization. Therefore, the rubber composition of the present invention may be unvulcanized or vulcanized.

The term "particle diameter" means the particle diameter of each particle when the linked particles are considered to be independent, and the particle diameter means the maximum particle diameter of the particles. That is, when the cross-sectional shape of the particle is circular, the diameter becomes the particle size,
When the cross-sectional shape of a particle is elliptical, its major axis is the particle size.

Furthermore, "when the cross-sectional area of particles having a particle size 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 cross-sectional area of particles having a particle size of 0.1 μm or more distributed therein is measured. This measurement can be performed, for example, by observing the fluororubber composition with a scanning electron microscope. Note that this observation does not have to be performed for the entire rubber composition, and may be partially performed by deciding observation points (sampling points). The sampling points are preferably 4 to 30 points, particularly preferably 2 points.
0 to 30 places. 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 subdivided to calculate the area of each part, and this can be summed to obtain each particle cross-sectional area. 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 sectional area
The particle size at the point where the cumulative cross-sectional area of% is 30 μm or less ”
Means the following. That is, the cumulative cross-sectional area of 90% of the total cumulative cross-sectional area is derived, and the particle diameter of the particle at the point where the cumulative cross-sectional area of 90% is obtained (hereinafter referred to as “90%”).
"Cumulative cross-sectional area grain size"). An example of this is shown in FIG.
It is shown in the graph of No. 1. In this graph, the vertical axis represents the cumulative cross-sectional area ratio (%), and the horizontal axis represents the particle size (μm) of particles and the cross-sectional area (μm ² ) of the particle size. 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, 90
The particle size of the particles at the point corresponding to the% cumulative cross-sectional area is determined. Then, if the particle size of the particles at this point is 30 μm or less, the requirements of the present invention are satisfied.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in the rubber composition of the present invention, particles comprising at least one of reactive silicone oil and reactive fluorine oil as a release agent are uniformly dispersed in the fluorine rubber matrix, In addition, the particles are reactively fixed to the fluororubber matrix in a partially continuous state inside the fluororubber matrix. A plan view of this rubber composition is schematically shown in FIG. That is, in this rubber composition 1, the particles 2 formed of reactive silicone oil or the like react with the fluororubber matrix 1a to chemically bond with the fluororubber molecules. This chemical bond differs depending on the type of reactive group such as reactive silicone oil. Then, as described above, the particle size distribution of the particles 2 is set so that the 90% cumulative cross-sectional area particle size is 30 μm or less. Moreover,
As shown in FIG. 2, which is a cross-sectional view in the thickness direction, each of the particles 2 has a three-dimensional connection in which a plurality of adjacent particles 2 are mainly connected in the thickness direction. The three-dimensional connection can be observed by wiping the surface of the vulcanized molded product of the rubber composition with a solvent such as acetone to remove the oil component.

When the outermost layer of the developing roll is formed using the rubber composition having the above structure, the reactive silicone oil or the like, which is a release agent, is reactively fixed inside the matrix in a uniformly dispersed state. Therefore, it does not exude into a large aggregate and exudes almost uniformly. Therefore, high toner releasability is exhibited on the entire surface of the roll. Particularly, in the rubber composition of the present invention, since the particles of the oil component are not independent but are partially connected, the oil is continuously supplied, and the high toner releasability is long. It has the advantage of lasting for a period of time. Therefore, the occurrence of toner filming, which has been a problem in the related art, can be effectively and long-term prevented.

Next, the present invention will be described in detail.

The rubber composition of the present invention comprises a fluororubber and
It contains at least one of reactive silicone oil (component A) and reactive fluorine oil (component B).

The above-mentioned fluororubber serves as a matrix component, and the kind thereof is not particularly limited, but tetrafluoroethylene-polypropylene (TFE) is used because of its low polymer viscosity and good filler dispersibility.
It is preferable to use -PP) copolymer, and it is particularly preferable to use a random copolymer having a structure represented by the following general formula (1).

[0015]

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) compounded in the fluororubber serve as a release agent for the toner. Both the B component may be blended, or one of the both components may be blended alone.

The above-mentioned reactive silicone oil (component A) and reactive fluorine oil (component B) are both 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 oil component is fixed to the fluororubber matrix. The manner of this reaction fixation is shown below for each of the above reaction groups.

[Hydroxyl group]

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[Amino group]

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[Mercapto group]

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[Epoxy group]

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[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 their arrangement differs depending on the type of oil and the like.

Of 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, and particularly preferably both have an average molecular weight of 15
It is 00 to 20000. Furthermore, the total compounding ratio (A + B) of these reactive silicone oil (component A) and reactive fluorine oil (component B) is 0.5 to 100 relative to 100 parts by weight of fluororubber (hereinafter abbreviated as “part”). The range of parts is preferable, and the range of 15 to 50 parts is particularly preferable.

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

[Reactive Silicone Oil Having Hydroxyl Group]

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[Reactive Silicone Oil Having Amino Group]

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[Reactive Silicone Oil Having Mercapto Group]

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[Reactive Silicone Oil Having Epoxy Group]

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[Reactive Silicone Oil Having Carboxyl Group]

[Chemical 12]

[Reactive Silicone Oil Having Methacrylic Group]

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[Reactive Fluorine Oil Having Hydroxyl Group]

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[Reactive Fluorine Oil Having Amino Group]

[Chemical 15]

[Reactive Fluorine Oil Having Mercapto Group]

Embedded image

[Reactive Fluorine Oil Having Epoxy Group]

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[Reactive Fluorine Oil Having Carboxyl Group]

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[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.

In addition to the above-mentioned reactive silicone oil (component A) and reactive fluorine oil (component B), the rubber composition of the present invention contains non-reactive silicone oil (component C) and non-reactive fluorine oil. (D component) can be blended. These non-reactive oils have no reactive group for chemically bonding with fluororubber molecules, but are fixed to the fluororubber matrix when used in combination with the above-mentioned reactive silicone oil or the like. This is presumed to be because the non-reactive oil is mixed in the particles made of the reactive oil and both are bonded by a hydrophobic bond, and as a result, the non-reactive oil is fixed to the fluororubber matrix. Therefore, even if the above-mentioned non-reactive oil is used, if it is a predetermined amount, there will be no adverse effect such as generation of large aggregates thereof.

The above non-reactive silicone oil (component C)
Preferred are those 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 non-reactive silicone oils, because of their high releasability and thermal stability,
The average molecular weight is preferably in the range of 500 to 100,000, particularly preferably the average molecular weight of 2,000 to 50,000.
It is in the range of.

The blending ratio of the non-reactive silicone oil is usually 10 to 10 with respect to 100 parts of fluororubber.
The range is set to 0 part, preferably 20 to 50 parts, and particularly preferably 30 to 40 parts.

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

[Non-Reactive Silicone Oil Having Alkyl Group]

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[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 having 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.

In addition to the above oil component, the rubber composition of the present invention has an appropriate volume electric resistance (10 ⁷ to 10 10).
^An ionic conductive agent can be blended for the purpose of imparting 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, calcium hydroxide, magnesium oxide, calcium oxide, red lead,
An acid acceptor such as litharge and a vulcanizing agent such as peroxide, bisphenol A, bisphenol AF, and hexamethylenediamine can be appropriately blended as necessary. As will be described later, the vulcanizing agent is preferably blended each time the rubber composition of the present invention is used (before coating).

Next, the rubber composition of the present invention can be produced 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 to this and kneading, at least one of reactive silicone oil (component A) and reactive fluorine oil (component B), and if necessary, non-reactive silicone oil (component C), non-reactive Fluorine oil (D component) and other components are added, and kneading is continued. Then, after the torque of the kneader increases, the kneading is stopped and the kneaded product is taken out. This kneaded product is sheeted with an open roll and then dissolved in a solvent to prepare a rubber composition (coating liquid). 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. At this stage, it is preferable that the vulcanizing agent is not compounded but compounded before use (before coating).

The rubber composition of the present invention can be prepared by the following method (second method) in addition to the above-mentioned manufacturing method.

That is, first, 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 the boiling point of the solvent or lower, and particularly preferably in the range of 50 to 80 ° C. Further, at the time of this adjustment, it is preferable that the vulcanizing agent is not compounded but compounded 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 above-mentioned 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 made of reactive silicone oil (release agent) in fluororubber matrix have 90% cumulative cross-sectional area particle size of 3
When the particle size is 0 μm or less, the particles are uniformly dispersed, and the particles are reactively fixed to the fluororubber matrix (between fluororubber molecules) in a state where they are partially connected inside the fluororubber matrix (see FIGS. 1 and 2) . As a result, as described above, the mold releasability is maintained for a long period of time without the formation 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 0.1 to 5 μm.
m.

Next, an example in which this rubber composition is applied to the formation of the outermost layer of the developing roll will be shown.

As the developing roll, as shown in FIG. 3, an innermost layer 11 made of an elastic body, an intermediate layer 12 and an outermost layer 13 made of a fluororubber composition are provided on the outer periphery of a shaft body 10 such as a cored bar. It has a three-layer structure.

The developing roll having the three-layer structure is manufactured as follows. That is, first, materials for forming the innermost layer 11 and the intermediate layer 12 are prepared.

Materials for forming the innermost layer 11 and the intermediate layer 12 are not particularly limited, and conventionally known materials are used. Examples of the material for forming the innermost layer 11 include ethylene-propylene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, polyurethane elastomer, and the like in which carbon black is blended.

As the material for forming the intermediate layer 12, for example, EPDM, SBR, nitrile rubber, hydrogenated nitrile rubber, polyurethane elastomer, polyester, N
-Methoxymethylated nylon and the like mixed with a conductive agent such as carbon black, metal oxide, and quaternary ammonium salt.

Then, the innermost layer 11 and the intermediate layer 12
As a method for preparing the forming material, a conventionally known method is applied. Taking this example, first, the forming material (compound form) of the innermost layer 11 is prepared by kneading the above-mentioned components with a kneader such as a kneader. The material for forming the intermediate layer 12 (coating liquid) is prepared by kneading with a ball mill, a roll, or the like, adding a solvent to the mixture, and stirring the mixture.

Next, the innermost layer 11 and the intermediate layer 12 are formed on the outer periphery of the shaft body 10 by a conventional method to prepare a roll substrate. For example, as shown in FIG. 4, a compound-like innermost layer forming material is cast into the lower lid 15 and the cylindrical mold 16 on which the shaft body 10 is set, and the upper lid 17 is fitted onto the cylindrical mold 16. In this state, the entire roll mold is heated (vulcanization treatment, conditions: 150 to 200 ° C. × 20 to 40 minutes), and the innermost layer 11
To form Then, the shaft body 10 on which the innermost layer 11 is formed
Is removed from the mold, and if necessary, the residue of the vulcanizing agent is removed by evaporation. 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. To form. The coating is a dipping method,
A conventionally known coating method such as a spray method or a roll coating method can be applied. In this way, a roll substrate having the innermost layer 11 and the intermediate layer 12 formed on the outer periphery of the shaft body 10 is manufactured.

On the other hand, a vulcanizing agent is added to the rubber composition (coating liquid) of the present invention. 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 the coating, drying and heat treatment (vulcanization treatment, conditions: 150 to 200 ° C. × 20 to 40 minutes) are performed to remove the solvent in the rubber composition by evaporation and to crosslink the fluororubber component. . In this way, a developing roll having a three-layer structure as shown in FIG. 3 can be manufactured. In the developing roll, the thickness of each layer is appropriately determined, but the thickness of the innermost layer 11 is preferably set in the range of 2 to 10 mm, and particularly preferably 3 to.
It is 6 mm. The thickness of the intermediate layer 12 is 3 to 90 μm.
It is preferable to set in the range of, and particularly preferable thickness is 5 to 15 μm. And the thickness of the outermost layer 13 is 2
0 to 100 μm is preferable, and 30 to 70 is particularly preferable.
μm.

In this way, a developing roll having the outermost layer 13 formed from the rubber composition of the present invention can be prepared. However, the use of the rubber composition of the present invention is not limited to this. That is, the rubber composition of the present invention is characterized by being able to impart excellent toner releasability to the roll surface for a long period of time. It is also effective when applied to. Examples of such a roll include a fixing roll and the like.

[0069]

As described above, in the rubber composition of the present invention, at least one of reactive silicone oil and reactive fluorine oil as a releasing agent is dispersed in a fluororubber matrix in a special particle size distribution, In addition, the particles are reactively fixed to the fluororubber matrix in a state where they are partially connected inside the fluororubber matrix. Therefore, for example, in the developing roll having the outermost layer formed by using the rubber composition of the present invention, a large aggregate of the silicone oil as the toner releasing agent has been a problem in the outermost layer of the conventional developing roll. It is possible to prevent the occurrence of blemishes and the exudation on the roll surface. Particularly, in the rubber composition of the present invention, since the particles of the oil component are not independent but are partially connected, the oil is continuously supplied, and the high toner releasability is long. It has the advantage of lasting for a period of time. Therefore, a good quality copy image can be obtained for a long period of time.

Next, examples will be described together with comparative examples.

Prior to the 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.

[0073]

Examples 1 to 7 and Comparative Examples 1 to 4 An outermost layer was formed on the outer peripheral surface of the roll substrate by using the rubber composition prepared by the above-mentioned second method. That is, Tables 1 to 3 described later
The materials shown in Table 1 were blended in the proportions shown in these tables, and a fluororubber composition was prepared according to the above-mentioned second method. 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 the 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 5 mm.
0 μm.

With respect to the developing rolls of Examples 1 to 7 and Comparative Examples 1 to 4 thus obtained, the copied images were evaluated and the presence or absence of toner filming was examined, and the results are shown in Tables 1 to 1 below. The results are shown in Table 3. The average particle diameter of the particles and the 90% cumulative cross-sectional area particle diameter are also shown in these tables. In addition, the said evaluation and measurement followed the following method.

[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. Further, 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 was 1 μm or more, the presence or absence of the toner filming was determined as the occurrence of toner filming.

[90% cumulative cross-sectional area particle size] As shown in FIG. 12A, two cuts are made in the elastic body portion (inner layer, intermediate layer, outermost layer) of the developing roll 20 at right angles to the axial direction. A ring 20 was cut into pieces, and a slit was made in the axial direction and the pieces were taken out from the core metal to prepare a sample 20a as shown in FIG. Then, as shown in the cross-sectional portion of the sample 20a in FIG. 6C, four locations (outermost layer portions) surrounded by dotted lines were observed with a scanning electron microscope (S-4100, manufactured by Horiba, Ltd.). . Then, using the image processor (Spica II, manufactured by Nippon Avionics) according to the procedure described above,
The 0% cumulative cross-sectional area grain size was automatically determined.

[0078]

[Table 1]

[0079]

[Table 2]

[0080]

[Table 3]

From Tables 1 and 2 above, the developing rolls of Examples 1 to 7 in which the 90% cumulative cross-sectional area particle size of the particles of reactive silicone oil or the like are 30 μm or less have no problem in copied images and fine line Was clearly copied, and no toner filming occurred. On the other hand, from Table 3 above, toner filming occurred 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. exceeded 30 μm.

Next, the state of particles made of reactive silicone oil or the like in the outermost layer of the developing rolls of Example 1 and Comparative Example 1 was examined using the scanning electron microscope. The results are shown in the photographs in FIGS.

FIG. 5 is a photograph showing the condition of the outermost layer surface of the developing roll of Example 1 (magnification: 10,000 times), and FIG. 6 is a photograph showing the condition of the inside of the same outermost layer (cross section in the thickness direction) ( The magnification is 10,000 times). 7 is a photograph showing the condition of the outermost layer surface of the developing roller of Comparative Example 1 (magnification: 10,000 times), and FIG. 8 is a photograph showing the condition of the same outermost layer (cross section in the thickness direction) (magnification 1). 10,000 times). From the photographs of FIGS. 5 and 6, it can be seen that in the developing roller of Example 1, the oil particles have a very small particle size and are uniformly dispersed in the fluororubber matrix. On the other hand, from the photographs of FIGS. 7 and 8, it can be seen that in the developing roller of Comparative Example 1, the oil particles have a large particle size and are extremely unevenly distributed.

The surface of the developing roll of Example 2 was wiped with a solvent (acetone) to remove the oil component dispersed in the outermost layer, and the state of voids obtained was examined. FIG.
FIG. 10 is a photograph (magnification: 2500 times) showing the state of the outermost layer surface, and FIG. 10 is a photograph (magnification: 2500 times) showing the state inside the same outermost layer (cross section in the thickness direction). From these photographs, it is understood that the oil particles uniformly dispersed in the fluororubber matrix are partially connected inside the fluororubber matrix and are connected to some extent.

Based on the results of these electron microscope observations and the results of Tables 1 to 3 (toner filming), it was comprehensively judged that 90 particles of the reactive silicone oil dispersed in the fluororubber matrix were present. The% cumulative cross-sectional area particle size was 30 μm or less, and the particles of the example were reactively fixed to the fluororubber matrix in a state where they were partially connected to each other, so that the toner filming of the example product was prevented. I can say.

[Brief description of drawings]

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

FIG. 2 is a schematic cross-sectional view in the thickness direction showing a microscopic structure of the rubber composition of the present invention.

FIG. 3 is a cross-sectional view showing a general structure of a developing roll.

FIG. 4 is an explanatory diagram of a manufacturing method of the developing roll.

FIG. 5 is a photomicrograph showing the structure of reactive silicone oil particles on the surface of the outermost layer obtained by applying one embodiment of the present invention to the outermost layer of a developing roll.

FIG. 6 is a micrograph showing the structure of reactive silicone oil particles inside the outermost layer.

FIG. 7 is a micrograph showing the structure of reactive silicone oil particles on the surface of the outermost layer obtained by applying the comparative example product to the outermost layer of the developing roll.

FIG. 8 is a micrograph showing the structure of reactive silicone oil particles inside the outermost layer.

FIG. 9 is a drawing showing that the above example product is applied to the outermost layer of a developing roll,
It is a microscope picture which shows the structure of the reactive silicone oil particle in the surface of the outermost layer after wiping the outermost layer surface with acetone.

FIG. 10 is a micrograph showing the structure of reactive silicone oil particles inside the outermost layer.

FIG. 11 is a graph showing the relationship between the particle size of particles and the cumulative cross-sectional area ratio of particles.

FIG. 12A is a perspective view showing a state in which a notch is made in a developing roll, FIG. 12B is a perspective view of a sample cut out from the developing roll, and FIG. 12C is a sectional view of the sample. .

[Explanation of symbols]

 1 rubber composition 1a fluororubber matrix 2 particles

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Continuation of front page (72) Inventor Akihiko Kaji 3600 Gyokutsuyama, Komaki City, Aichi Tokai Rubber Industry Co., Ltd.

Claims (6)

[Claims] 1. A rubber composition comprising a fluororubber as a matrix component, wherein particles of at least one of reactive silicone oil and reactive fluorooil are dispersed in the fluororubber matrix, wherein the particles are the fluororubber. The cross-sectional area of particles having a particle size of 0.1 μm or more, which are reactively fixed to the fluororubber matrix in a state where they are partially linked inside the matrix, are measured, and these are sequentially accumulated from the smallest. The rubber composition is characterized in that the particle size at the point where the cumulative cross-sectional area is 90% of this 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 rubber composition 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. Stuff. 3. The rubber composition 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 rubber composition according to any one of items 1 to 3. 5. The rubber composition according to claim 1, wherein the particles contain at least one of a non-reactive silicone oil and a non-reactive fluorine oil. 6. The rubber composition according to claim 5, wherein the non-reactive silicone oil has a higher alcohol ester group, and the non-reactive fluorine oil is perfluoropolyether.