JP3186541B2 - Conductive member and electrophotographic apparatus using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive member used in a mechanism such as electrophotography and an electrophotographic apparatus using the same.

[0002]

2. Description of the Related Art In recent years, with the progress of electrophotographic technology, conductive members (volume resistivity 10 ⁵⁾ used in electrophotographic processes have been developed.
There is an increasing demand for ~10 ¹⁰ Ω · cm), especially a conductive roller to be used in the development or transfer such process has attracted attention. Conventionally, conductive members used in such applications include polymer substances such as polymer elastomers and polymer foams, inorganic ionic substances such as lithium perchlorate and sodium perchlorate, and modified aliphatic dimethylethyl ammonium ethoxide. A polymer member adjusted to a predetermined resistance value by mixing a conductive agent such as a cationic surfactant such as sulfate or an organic ionic substance such as a quaternary ammonium salt such as tetrabutylammonium fluoride is used. Have been.

[0003] As such a polymer member, polyurethane, particularly polyurethane comprising polyether polyol and polyisocyanate, is frequently used because of its properties, handleability, and price. Among the polyether polyols, an initiator such as glycerin is used. Polyether polyols obtained by addition-polymerizing propylene oxide with propylene oxide and polyether polyols further having ethylene oxide added to the terminal thereof are used.

[0004]

The conductive member used in the electrophotographic process has not only a predetermined electric resistance value but also a sufficient resistance to heat generation when a high voltage is applied for a long time, especially a polymer. It is necessary that the photoconductor is not contaminated by the disassembly of the member and that the electrical resistance of the member does not change. However, when the polyol component in the urethane is only propylene oxide, heat resistance is good, but molding is difficult due to poor reactivity, or ions are difficult to move due to low hydrophilicity, and conductivity of the roller is secured. Is difficult. In addition, those having ethylene oxide added to the terminal have high reactivity because of a large number of primary hydroxyl groups, and have a problem that heat resistance is inferior although conductivity can be ensured because hydrophilicity is increased. Therefore, an object of the present invention is to solve the drawbacks of the conventional conductive polymer member and to provide a conductive polymer member having excellent heat resistance.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, in a conductive member used in a mechanism such as electrophotography, the conductive member is a polyol component. As glycerin, heat resistance is improved by using a conductive member characterized by being made of urethane containing polyether polyol to which ethylene oxide and propylene oxide are randomly added,
The inventors have found that reactivity and conductivity can be ensured, and have accomplished the present invention.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The conductive polymer member according to the present invention is obtained by adding and mixing a conductivity-imparting material to a polyurethane foam or an elastomer, and a polyether obtained by randomly adding ethylene oxide and propylene oxide to glycerin or the like as a raw material of polyurethane. It uses a polyol.

The structure of the polyether polyol is as follows:
Any known initiator such as ethylene glycol, glycerin, trimethylolpropane, ethylenediamine, sorbitol, or sucrose may be obtained by randomly adding ethylene oxide and propylene oxide. The proportion of ethylene oxide contained in all the polyether polyol components is 3 to 50% by weight, more preferably 5 to 20% by weight.
When the amount is less than 5%, molding is difficult due to poor reactivity, and ions are difficult to move due to low hydrophilicity, and it is difficult to secure the conductivity of the roller. In addition, 20%
If it is more than this, the heat resistance becomes poor, which is not preferable. In addition, other known polyols such as polyether polyol, polyester polyol, acrylic polyol, acrylonitrile polyol, polytetramethylene ether polyol, polybutadiene polyol, polyisoprene polyol, and polycarbonate polyol are mixed within a range that does not impair the effects of the present invention. You may.

As the polyisocyanate compound, polyisocyanates used for producing general flexible polyurethane foams and urethane elastomers, that is, polyisocyanates,
Tolylene diisocyanate (TDI), crude TDI, diphenylmethane diisocyanate (MDI), crude MD
I), an aliphatic polyisocyanate having 2 to 18 carbon atoms, an alicyclic polyisocyanate having 4 to 15 carbon atoms, and a mixture or a modified product of these polyisocyanates.

As the chain extender, known polyols such as ethylene glycol, propanediol, and butanediol can be used, but polyols having a molecular weight of 500 or less, preferably 200 or less are particularly preferably used.

[0010] The conductive member of the present invention comprises the above urethane as a base material and a conductivity imparting agent added thereto. There is no limitation on the conductive agent for imparting conductivity, but powders of metals and metal oxides and whiskers, fillers such as carbon black, and inorganic ionic substances such as lithium perchlorate, sodium perchlorate, and calcium perchlorate And / or a cationic surfactant such as lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, modified aliphatic dimethyl ethyl ammonium chloride, lauryl Amphoteric surfactants such as betaine, stearyl betaine, dimethyl alkyllauryl betaine, tetraethylammonium perchlorate, tetrabutylammonium perchlorate, Tsu of 4, such as tetrabutylammonium
Organic ionic substances such as quaternary ammonium salts and / or antistatic agents such as hydrophilic polyethers and polyesters, tetracyanoethylene, tetracyanoquinodimethane, benzoquinone, chloranil, anthraquinone, anthracene, dichlorodicyanobenzoquinone, ferrocene, phthalocyanine, etc. Electron-accepting substances capable of forming a charge-transfer complex can be used, and electron-acceptors capable of forming a derivative or a charge-transfer complex of these compounds for the purpose of, for example, improving compatibility with the polyurethane as the base material. The substance may be used in the form of a complex with an electron donor such as tetrathiafulvalene or lithium.

As a method for producing polyurethane, a one-shot method or a prepolymer method is used. In particular, the prepolymer method is preferable because urethane with less contamination of the photoreceptor and excellent heat resistance can be obtained. The method of foaming is not limited, and a method using a foaming agent such as water or chlorofluorocarbon, a method of mixing air bubbles by mechanical stirring (mechanical floss method), and the like are used. In particular, the mechanical floss method is used. And a foam with less contamination of the photoreceptor can be obtained.

Although there is no limitation on the shape of the above-mentioned member for use in an electrophotographic apparatus, it is usually used in the form of a roller provided around a metal core or a block shape such as a blade. Although there is no limitation on the method of forming the roller, a method of polishing with a grindstone or a method of obtaining a foam or an elastomer with a self-skin using a mold adapted to the shape of the roller is used. The conductive polymer member of the present invention is suitably used as a conductive member used in an electrophotographic process, for example, a conductive roller used in a developing and transferring device.

[0013]

EXAMPLES The present invention will now be described specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples. [Example 1] Molecular weight of 3500, number of functional groups of 3, ethylene oxide was randomly added to the main chain, and its content was 12%.
Was mixed with tolylene diisocyanate and reacted at 60 ° C. for 15 hours to obtain a urethane prepolymer. To 100 parts of this urethane prepolymer, 6.05 parts of 1,4-butanediol, 4 parts of a silicone surfactant, 0.01 part of dibutyltin dilaurate
Parts, 0.1 part of a cationic surfactant mixture, 0.42 denatured aliphatic dimethylethylammonium ethosulfate
Parts and 2 parts of black pigment were added and mixed with a mixer. The mixture is heated at 110 ° C. where a shaft is previously placed.
And heated at 110 ° C. for 30 minutes to obtain a transfer roller having a conductive polyurethane foam layer formed on the shaft surface excluding both ends. The transfer roller was placed in an oven at 90 ° C. and kept heated, and the heat resistance was examined by visually observing the state every several hours. Table 1 shows the results.

[0014] The resistance of this transfer roller is
The measurement was performed on a copper plate with a load of 500 g applied to both sides using R8340A manufactured by st. The roller hardness was measured using an Asker C hardness meter. Table 2 shows the results. The resistance value of the roller was almost the same after the heat resistance test.

Comparative Example 1 A polyether polyol containing a molecular weight of 5,000, three functional groups and containing only propylene oxide was used, and 1,4-butanediol was used in an amount of 5.19.
The experiment was performed in the same manner as in Example 1 except that the components were mixed. Table 1 shows the results of heat resistance, and Table 2 shows resistance and hardness. Although heat resistance is considerably better than Comparative Examples 2 and 3, foaming cannot be carried out well due to low reactivity, and hardness becomes high. Also, the roller resistance is high because of low hydrophilicity.

Comparative Example 2 Example 1 was repeated except that a polyether polyol having a molecular weight of 4900, a functional group of 3, and ethylene oxide containing only 14.5% of ethylene oxide was used, and 4.76 parts of 1,4-butanediol was blended. An experiment was performed similarly. Table 1 shows the results of heat resistance, and Table 2 shows resistance and hardness.
The terminal ethylene oxide increases hydrophilicity and lowers roller resistance, but deteriorates heat resistance.

Comparative Example 3 Example 1 was repeated except that a polyether polyol having a molecular weight of 5,000, a number of functional groups of 3, and ethylene oxide containing 16% only at the terminal was used, and 6.47 parts of 1,4-butanediol was blended. An experiment was performed similarly. Table 1 shows the results of heat resistance, and Table 2 shows resistance and hardness. Since the terminal ethylene oxide was further increased as compared with Comparative Example 2, the roller resistance was low and the heat resistance was poor.

[0018]

[Table 1]

[0019]

[Table 2]

A comparison between the example and the comparative example shows that the roller of the example has particularly excellent heat resistance.
Further, the rollers of the examples have low roller resistance and excellent conductivity, which is clear.

[0021]

The conductive polymer member of the present invention imparts excellent heat resistance. If this is used for a roller used for development / transfer of an electrophotographic process, excellent durability can be obtained. Things.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takahiro Kawagoe 1302-57, Aobadai, Tokorozawa-shi, Saitama (56) References JP-A-2-228357 (JP, A) JP-A-53-41396 (JP, A) 50-2096 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 18/48

Claims (5)

(57) [Claims] 1. A conductive member used in a mechanism such as electrophotography, wherein the conductive member is made of urethane containing a polyether polyol in which ethylene oxide and propylene oxide are randomly added to glycerin as a polyol component. Characteristic conductive member. 2. In the above polyether polyol,
The conductive member according to claim 1, wherein the proportion of ethylene oxide contained in all polyether polyol components is 3 to 50% by weight. 3. The conductive member according to claim 1, wherein the polyether polyol is pre-polymerized with an isocyanate component in the polyurethane. 4. A latent image formed by carrying a developer on the surface of the conductive member according to claim 1 to form a thin film of the developer, and holding an electrostatic latent image on the surface in this state. An electrophotographic apparatus, comprising: a developing device for bringing the developer into contact with an image holding member to adhere the developer to the electrostatic latent image on the surface of the latent image holding member and visualizing the electrostatic latent image. 5. A transfer device for charging a recording medium with the conductive member according to claim 1 and transferring the developer to the recording medium from an electrostatic latent image visualized by the developer. An electrophotographic apparatus, characterized in that: