JP2001355628A - Conductive roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive roller used for, for example, an electrophotographic copier with a desirable pressure resistance without impairing its conductivity. SOLUTION: This conductive roller 1 comprises a conductive roller base material 3 formed by mixing conductive powder to an urethane resin component which is formed by mixing and dispersing hollow glass 6 and a thermal expansion substance of thermal expansion type microcapsules 7, and a shaft body 2 inserted in the center of the base material 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive roll used in, for example, an electrophotographic copying machine.

[0002]

BACKGROUND OF THE INVENTION In an electrophotographic copying machine, there is provided a charging roll for pressing against the outer surface of a photosensitive drum to charge the outer surface;
A conductive roll such as a developing roll for forming a toner image on the electrostatic latent image formed on the outer surface of the photosensitive drum and a cleaning roll for removing toner attached to the photosensitive drum is used. The conductive roll has a configuration in which a conductive roll base material having a shaft inserted in the center and, if desired, a protective coating and an electric resistance adjusting layer are further provided on the base material surface.

[0003]

2. Description of the Related Art The above-mentioned conductive roll has a moderate conductivity,
Elasticity and pressure resistance are required. A conductive agent such as carbon black is added to the conductive roll base to impart conductivity to the conductive roll. Further, in order to impart elasticity to the conductive roll, an elastic material (such as a urethane resin composition) is used for the conductive roll base material.

[0004]

When a roll base is prepared by adding a conductive agent to an elastic material, as in the case of the above-mentioned conductive roll, an attempt is made to obtain an appropriate conductivity (volume resistivity). As the volume ratio of the agent to the elastic material increases,
There has been a problem that sufficient pressure resistance cannot be obtained.

[0005]

In order to solve the above problems, the present invention provides a urethane resin composition obtained by mixing and dispersing a hollow glass (6) and a thermally expandable microcapsule (7). An object of the present invention is to provide a conductive roll (1) comprising a conductive roll base material (3) mixed with a powder, and a shaft (2) inserted at the center of the base material (3). Further hollow glass
A conductive roll comprising: a conductive roll base material (3A) obtained by mixing a conductive powder in a urethane resin composition in which (6) is mixed and dispersed; and a shaft (2) inserted into the center of the base material. (1A).

The urethane resin composition is preferably obtained by reacting a hydrogenated castor oil polyol with diisocyanate, and the hollow glass is preferably a borosilicate glass.

Further, a protective film (4) comprising an inorganic oxide film and / or an inorganic-organic hybrid film may be formed on the surface of the conductive roll substrate (3) by a sol-gel method. An electric resistance adjusting layer (5) may be further provided on the surface of the roll base material (3, 3A).

[0008]

[Function] Independently by mixing and dispersing a hollow body (a hollow glass (6) and a thermally expanded material of a thermally expanded microcapsule (7) or a hollow glass (6)) in a conductive roll base material (3, 3A). By providing the cell structure, the pressure resistance of the roll substrate (3, 3A) can be increased without reducing the ratio of the conductive agent to the elastic material. That is, the pressure resistance can be increased while ensuring the conductivity of the conductive roll base material (3, 3A).

Further, when a protective film (4) comprising an inorganic oxide film and / or an inorganic-organic hybrid film is formed on the surface of the conductive roll substrate (3, 3A) by a sol-gel method, hydrophilicity is obtained. Even with a substrate made of a polyurethane resin, moisture absorption and absorption are prevented, and the volume electric resistance value does not change. Since the film made of the inorganic oxide or the inorganic-organic hybrid is formed by the sol-gel method, the film thickness can be made thin and uniform, and the electric properties of the base material (3, 3A) are not significantly affected. Although it does not affect, since the coating made of the inorganic oxide or the inorganic-organic hybrid has a high electric resistance value, it is desirable to further provide an electric resistance adjusting layer (5) on the surface of the roll substrate (3, 3A).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to an embodiment shown in FIG.
(2), a conductive roll base material (3) into which the base material (3) is inserted, a protective coating (4) formed on the surface of the base material (3) if necessary, and an electric resistance adjustment formed thereon. (5).
As the shaft (2), a rod or pipe made of metal such as stainless steel or aluminum is used. The roll (1)
The base material (3) is made of a urethane resin composition which is a reaction product of a polyol and a diisocyanate.

Examples of the polyol include polyether-based polyols, polyester-based polyols, and polycarbonate-based polyols. Particularly preferred polyols are hydrogenated castor oil polyols. Use of the hydrogenated castor oil polyol can make the urethane resin particularly soft.

In addition to the above polyols, a reactive diluent such as an aliphatic diol and a dispersant such as a surfactant may be added to improve the dispersing effect of the conductive powder.

The diisocyanate includes, for example, tolylene diisocyanate, paraphenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, 1,4- Naphthalene diisocyanate, 4,4 '
-Diphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,
4'-diphenyl diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate,
3,3′-dimethoxy-4,4′-diphenyldiisocyanate, 2-chloro-1,4-phenyldiisocyanate, 1-chloro-2,4-phenylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,2 ', 5,5'-tetramethyl-4,4'-biphenylene diisocyanate, m-xylylene diisocyanate, ω-xylylene diisocyanate, ω'-xylylene diisocyanate Nart and the like are exemplified.

In the present invention, the above polyol and the above diisocyanate are mixed and reacted in one step, and if desired, a urethanization catalyst such as a metal catalyst, an amine catalyst or a carboxylic acid amine salt catalyst may be used. I can do it.

A hollow glass (6) and a heat-expandable microcapsule (7) are mixed and dispersed in the urethane resin composition to increase the pressure resistance.

As the hollow glass (6) mixed and dispersed in the resin composition in the substrate (3), a hollow glass (6) made of borosilicate glass is particularly desirable. The average particle size of the hollow glass (6) is about 20 to 60 .mu.m, and a desirable particle size is about 40 .mu.m.

The thermal expansion type microcapsules (7) to be mixed and dispersed in the urethane resin composition include isobutane (boiling point -12 ° C.), normal butane (boiling point -5 ° C.),
Desirable boiling points such as ethyl methyl ether (boiling point 7 ° C) and isopentane (boiling point 27.85 ° C)
Some capsules are filled with a thermoplastic resin capsule containing a liquid low-boiling solvent in the range of 0 ° C. The thermoplastic resin is preferably one that is hardly soluble or insoluble in the above-mentioned solvents, and one having a softening point of 200 ° C. or less. In order to make the thermoplastic resin hardly soluble or insoluble in the above solvent, a nitrile vinyl monomer such as acrylonitrile and methacrylonitrile is copolymerized. Desirable thermoplastic resins include, for example, methyl methacrylate-acrylonitrile copolymer and methyl methacrylate-acrylonitrile-methacrylonitrile copolymer. The above microcapsules
The average particle size of (7) is usually about 10 to 20 μm, and expands to about 50 to 120 μm by heating (when fully expanded, the volume becomes 40 times or more). 0.5 to 3% by weight is added. The heat-expandable microcapsules (7) are added to the urethane resin composition in an unexpanded state, a heat-expanded state, or a mixture of an unexpanded state and a heat-expanded state.

The above-mentioned urethane resin composition is used as a conductive roll.
In order to make the base material (3) of (1), the composition is further added with conductive powder such as carbon black, graphite, and metal powder,
The resistance value of the roll (1) is adjusted to, for example, 10 ² to 10 ¹⁰ Ω. Further, a slight amount of a third component such as polysiloxane such as polydimethylsiloxane may be added to the composition. When the polysiloxane is added to the composition, the releasability is improved.

The conductive roll (1) is prepared by adding a predetermined amount of the hollow glass (6), the heat-expandable microcapsules (7) and the conductive agent to the raw material of the urethane resin composition and mixing and dispersing the raw material to form the shaft (2). A roll substrate (3) is produced by injecting into an inserted mold and reaction-curing, and the surface of the roll substrate (3) thus obtained is coated with an inorganic oxide by a sol-gel method if desired. A protective film (4) comprising a film and / or an inorganic-organic hybrid film is formed, and an electric resistance adjusting layer (5) is further formed thereon.

When the inorganic oxide film is formed by the sol-gel method, it is prepared, for example, by hydrolyzing a metal cation or a metal alkoxide. In the case of the present invention, as the inorganic oxide film, Al, Si, Ti,
V, Mn, Fe, Co, Zn, Ge, Y, Zr, Nb,
Metal oxides such as Cd and Ta, or indium tin oxide (ITO) and the like are used alone or in combination of two or more. When the metal oxide is used to form the inorganic oxide film, the metal methoxide, ethoxide, propoxide, butoxide, or a part of the alkoxy group may be β-diketone, β-ketoester, alkanolamine, or alkyl. An alkoxide derivative substituted with an alkanolamine or the like is used alone or as a mixture of two or more.

When hydrolyzing the metal cation or metal alkoxide, the metal cation or metal alkoxide is dispersed or dissolved in a solvent. As the solvent used in this case, methanol, ethanol, alcohols such as isopropanol, acetone, ketones such as methyl ethyl ketone, aromatics such as toluene and xylene, ethyl acetate, acetates such as n-butyl acetate,
An acetate derivative such as ethyl acetoacetate, a metal cation such as cellosolve acetate, cellosolves such as n-butyl cellosolve, or an organic solvent capable of uniformly dispersing or dissolving the metal cation, or a mixture of two or more thereof. select.

In order to hydrolyze the metal cation or metal alkoxide in the solvent, the solution or dispersion is stirred in the presence of water. In this case, an acid such as hydrochloric acid, phosphoric acid or acetic acid can be used as a hydrolysis accelerator. However, since the acid catalyst affects the electrical characteristics of the formed protective film (4), it is not necessary to use an acid catalyst in the case of ions or alkoxides such as Ti, Al, and Zr because the hydrolysis rate is high.

When an inorganic-organic hybrid film is formed by the sol-gel method, an organic metal compound is further added as an organic component. In the present invention, an organic silicon compound or a fluorine-substituted organic silicon compound is selected. It is desirable.

The above-mentioned organosilicon compound includes, for example,
Dialkyl dialkoxysilane, terminal silanol polydimethylsiloxane, and the like can be used. Examples of the dialkyldialkoxysilane include, for example, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, dipropyl Examples include dimethoxysilane, dipropyldiethoxysilane, dipropyldipropoxysilane, dipropyldibutoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldipropoxysilane, diphenyldibutoxysilane, and the like. The terminal silanol polydimethylsiloxane has a molecular weight of 4
What is 00-6000 is preferable. Examples of the fluorine-substituted organosilicon compound include those obtained by substituting hydrogen in the alkyl group of the organosilicon compound with fluorine. Such compounds include, for _{example, CF 3 CH 2 CH 2 -Si} (OC 2 H 5) 3 and the like.

When the organic metal compound (organic component) is added to a dispersion or solution of the metal cation or metal alkoxide (inorganic component), the molar ratio of the organic component is in the range of 0.1 to 0.7. It is desirable to set so that When the molar ratio of the organic component is less than the above range, the flexibility of the formed film and the adhesion may be insufficient, and when the molar ratio of the organic component exceeds the above range, a reaction product of an inorganic component and an organic component described below does not gel. There is.

The dispersion or solution containing the above-mentioned inorganic component and organic component is hydrolyzed by stirring in the presence of water as in the case of the inorganic component alone or by adding a hydrolysis accelerator and stirring. React with the organic component to form an inorganic-organic hybrid coating. For example, in the case of a metal alkoxide and an organosilicon compound or a fluorine-substituted organosilicon compound, the alkoxy group of the metal alkoxide is hydrolyzed to generate a hydroxyl group, while the alkoxy group of the organosilicon compound is also hydrolyzed to a silanol group (terminal In the case of silanol polydimethylsiloxane, the hydroxyl group of the above-mentioned inorganic component and the silanol group of the above-mentioned organic component are combined by a condensation reaction to perform hybridization.

The sol prepared by the above method is applied to the surface of the roll substrate (3) by a well-known coating method such as dipping, spraying, roll coating, flow coating and the like, and is gelled. Roll base material of the above sol (3)
The application to the surface may be repeated several times. This sol-gel conversion simply involves drying the sol coating layer naturally or
It is common to heat to a temperature in the range of 450 ° C. and heat and dry for 20 seconds to 10 hours. Thus, the protective film (4) is formed on the surface of the roll substrate (3), and the film thickness of the protective film (4) is usually 0.1 to 10.0 μm.
Thickness.

In order to form the electric resistance adjusting layer (5), one or more of a thermoplastic resin such as a urethane resin, a polyester resin, a melamine resin, an epoxy resin, an acrylic resin, a polyamide resin or a thermosetting resin, or Epichlorohydrin rubber, ethylene-propylene-diene rubber, silicone rubber, acrylonitrile-butadiene copolymer rubber, one or more rubbers such as polynorbornene rubber, or one or more of the above resins and one or more of the above rubbers A solution prepared by dissolving a mixture of two or more kinds in an organic solvent or the like and mixing the above-described conductive powder with the solution is applied and dried.

As another embodiment, as shown in FIG. 2, a conductive roll (1A) is added to a raw material of the urethane resin composition and a predetermined amount of a conductive agent and only a hollow glass (6) as a hollow body are mixed and dispersed. At the very least, the shaft (2) is injected into the inserted mold and cured by reaction to form a roll substrate (3).
A) may be manufactured. Further, if desired, a protective film (4) composed of an inorganic oxide film and / or an inorganic-organic hybrid film is formed on the surface of the obtained roll substrate (3A) by a sol-gel method, and further, an electric Resistance adjustment layer
(5) may be formed.

Example 1 A composition having the following composition was charged into a mold having a shaft inserted therein, and heated to about 100 to 150 ° C. to cure the composition to produce a conductive roll. Hydrogenated castor oil polyol 100 parts by weight Diphenylmethane diisocyanate 13.43 parts by weight Dibutyltin dilaurate 0.03 parts by weight Ionic surfactant 0.15 parts by weight Carbon black 7.5 parts by weight Hollow glass * ¹³ parts by weight Thermal expansion type microcapsules * ² 1 part by weight * ¹ hollow glass: Fuji balloon S-45, Fuji serial chemical Co. Ltd., average particle diameter of about 40μm borosilicate hollow glass * ² thermal expansion microcapsules: Expancel 051DE, Aix Pancel, average particle size about 50μm

The volume resistivity of the conductive roll (Example 1) obtained in Example 1 was 4.76 log Ω · cm.

Example 2 A composition having the following composition was charged into a mold having a shaft inserted therein, and heated to about 100 to 150 ° C. to cure the composition to produce a conductive roll. Hydrogenated castor oil polyol 100 parts by weight Diphenylmethane diisocyanate 13.43 parts by weight Dibutyltin dilaurate 0.03 parts by weight Ionic surfactant 0.15 parts by weight Carbon black 7.5 parts by weight Hollow glass * ¹ 7.5 parts by weight * ¹ Hollow glass: same as in Example 1

The volume resistivity of the conductive roll (Example 2) obtained in Example 2 was 4.74 log Ω · cm.

[Comparative Example] A composition having the following composition was filled in a mold having a shaft inserted therein, and heated to about 100 to 150 ° C to cure the composition to produce a conductive roll. Hydrogenated castor oil polyol 100 parts by weight Diphenylmethane diisocyanate 13.43 parts by weight Dibutyltin dilaurate 0.03 parts by weight Ionic surfactant 0.15 parts by weight Carbon black 7.5 parts by weight Thermal expansion type microcapsule * ²¹ 1 part by weight Part * ² Thermal expansion type microcapsule: same as in Example 1 above

The volume resistivity of the conductive roll (comparative example) obtained in the above comparative example was 4.49 log Ω · cm.

[Test] A test was conducted to evaluate the pressure resistance (V) of the conductive rolls obtained in Examples 1 and 2 and Comparative Example. The method of the pressure resistance test will be described below.

Electrodes having a width of 0.5 mm and a diameter of 10 to 14 mm
(8) is brought into contact with the conductive roll (1), and with the rotation of the conductive roll (1) (the direction of rotation indicated by arrow A in FIG.
(0-150 rpm), allowing the electrode (8) to rotate (in the direction of arrow B in the figure), and applying a voltage by connecting a high-voltage power supply (9) to the conductive roll (1) and the electrode (8). . Apply a predetermined voltage (V) between the conductive roll (1) and the electrode (8).
Apply for 0 seconds, and if no dielectric breakdown (excessive current and breakage of conductive roll (1)) is observed,
(1) is determined to have a withstand voltage at the predetermined voltage.
The conductive roll (1) further determines the presence or absence of pressure resistance by increasing the applied voltage. The applied voltage is 100V
Conductive roll (1)
Change the setting position of the upper electrode (8).

The pressure resistance (V) of the conductive roll (1) is the largest voltage applied to the conductive roll (1) determined to have pressure resistance in the above test. With respect to the conductive rolls (Example 1, Example 2, and Comparative Example), the above test was performed to evaluate the pressure resistance (V). The results are shown in Table 1.

[0039]

[Table 1]

According to Table 1, the pressure resistance of the conductive roll to which the hollow glass was added (Example 1) was significantly higher than the pressure resistance of the conductive roll to which only the thermal expansion type microcapsules were added. You can see that it is. Also, when only a predetermined amount of hollow glass is added to the conductive roll as a hollow body as in Example 2, it can be seen that the best pressure resistance is obtained.

[0041]

According to the present invention, a conductive roll base material having sufficient conductivity and pressure resistance is provided by blending hollow glass with the conductive roll base material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conductive roll according to an embodiment.

FIG. 2 is a cross-sectional view of a conductive roll according to another embodiment.

FIG. 3 is an explanatory view of a pressure resistance test method.

[Explanation of symbols]

 1 Conductive roll 2 Shaft 3 Conductive roll base 4 Protective coating 5 Electric resistance adjusting layer 6 Hollow glass 7 Thermal expansion type microcapsule

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 3/00 C08K 3/00 4F074 7/28 7/28 4J002 C08L 75/04 C08L 75/04 G03G 15 / 02 101 G03G 15/02 101 15/08 501 15/08 501D 21/10 21/00 312 (72) Inventor Takashi Suzuki 1900, Ifuna-cho, Suzuka-shi, Mie Suzuka Fuji Xerox Co., Ltd. (72) Inventor Shinto Takuya 1900, Ifuna-cho, Suzuka-shi, Mie F-term (reference) in Suzuka Fuji Xerox Co., Ltd. HA05 HA12 HA15 HA20 HA33 HA37 HA48 HA52 HA60 4F006 AA37 AB74 BA02 CA01 DA04 4F074 AA78 AC01 AC02 AG08 BA35 BA37 BA38 BA91 CB62 CB83 DA59 4J002 CK021 DA028 DA038 DA068 DL007 FA107 FD118 FD326

Claims (6)

[Claims] 1. A conductive roll base material obtained by mixing a conductive powder with a urethane resin composition obtained by mixing and dispersing a thermally expanded material of a heat-expandable microcapsule and a hollow glass; Conductive roll, comprising a shaft body 2. A conductive roll base material in which conductive powder is mixed in a urethane resin composition in which hollow glass is mixed and dispersed, and a shaft inserted in the center of the base material. Conductive roll 3. The conductive roll according to claim 1, wherein the urethane resin composition is obtained by reacting a hydrogenated castor oil polyol with a diisocyanate. 4. The conductive roll according to claim 1, wherein said hollow glass is borosilicate glass. 5. A conductive film according to claim 1, wherein a protective film comprising an inorganic oxide film and / or an inorganic-organic hybrid film is formed on the surface of said conductive roll substrate by a sol-gel method. Sex roll 6. The conductive roll according to claim 5, wherein an electric resistance adjusting layer is further provided on the surface of the roll base material.