JPH1124450A - Electrically conductive elastic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrically conductive elastic member excellent in ozone resistance, having high mechanical strength even by production by a one-shot method, also having relatively low hardness and suitable for use as a transfer roll in an electrophotographic device, etc. SOLUTION: The electrically conductive elastic member is produced using an electrically conductive material contg. polyurethane foam obtd. using condensed polyester polyol, an electric conductivity imparting agent and a silicone foam regulating agent having the polyether part in which the ratio between oxyethylene units and oxypropylene units is 80:20 to 100:0 and/or a polyethylene glycol type nonionic surfactant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive elastic member, and more particularly, it has good ozone resistance, has sufficient mechanical strength even when manufactured by a one-shot method, and has a comparative hardness. The present invention relates to a conductive elastic member suitable for a transfer roller or the like in an electrophotographic apparatus.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic process of a copying machine, an electrostatic recording device or the like, generally, first, a photoconductive substance [for example, ZnO, CdS, Se, OPC (organic semiconductor), α]
-Si etc.) to uniformly charge the surface of the photoreceptor,
An image is projected from the optical system, a latent image is formed by erasing the charge of the light-exposed portion, a developer such as toner is attached (developed), and a transfer material such as paper (recording medium) is formed. A method of performing copying by transferring a toner image to a printer has been adopted.

A conductive elastic member such as a transfer roller used in such an electrophotographic process or the like is required to have relatively low hardness, and a foam such as a polyurethane foam is usually used. In order to obtain a good image, the foam used for these conductive elastic members has a low hardness (roller hardness of 20 to 50 degrees, more preferably 25 to 45 degrees in Asker C hardness) and fineness. It is required to have a uniform cell structure (bubble structure).

[0004] For this reason, polyurethane foams used for these applications usually use, as a polyol component, polyether polyols which can be easily imparted with an ionic conductive agent to obtain relatively low-hardness foams. In order to obtain fine and uniform air bubbles, foaming by mechanical stirring, that is, a mechanical froth method, is used without using a foaming agent such as water, chlorofluorocarbon, alternative fluorocarbon, and cyclopentane. However, the transfer roller and the like made of the polyurethane foam manufactured as described above are relatively weak to ozone generated from the electrophotographic apparatus, and as a result, stickiness is generated due to decomposition of the roller surface, the roller hardness is reduced, and the roller resistance is reduced. This has the drawback of causing defects such as a decrease in image quality and of causing image defects. In addition to these drawbacks, a transfer roller or the like made of a polyurethane foam manufactured by a one-shot method using a polyether polyol has a tensile strength,
It also has drawbacks in that the mechanical strength such as elongation is relatively small, and the ends of the rollers are easily chipped in the roller manufacturing process and the like.

In order to improve the disadvantages of the polyether-based polyurethane foam, it is conceivable to use a condensed polyester-based polyurethane foam having good ozone resistance and relatively high mechanical strength. But,
Condensed polyester-based polyurethane foam is foamed by mechanical stirring without using a foaming agent, in order to obtain fine and uniform cells, that is, when produced by a mechanical floss method, the foam generated during foaming gels the foam. There is a problem that bubbles are easily broken before. As a result, it is difficult to reduce the foam density of the condensed polyester polyurethane foam, and the resulting roller has a high roller hardness of 50 degrees or more, and is required to have a low hardness such as a transfer roller. Could not be used until now.

[0006]

Under such circumstances, the present invention has good ozone resistance, has sufficient mechanical strength even when manufactured by the one-shot method, and has a roller hardness. An object of the present invention is to provide a conductive elastic member which is relatively low and is suitable as a transfer roller or the like in an electrophotographic apparatus.

[0007]

Means for Solving the Problems The present inventors have intensively studied to develop a conductive elastic member having the above-mentioned preferable properties. In the process, by using a condensed polyester polyol, we decided to reduce the foam density without using a foaming agent and aim to obtain a roller with relatively low hardness, and to select a foam stabilizer suitable for that purpose. The research continued with a focus. As a result, by using a silicone foam stabilizer having a specific polyether portion or a polyethylene glycol type nonionic surfactant as a foam stabilizer, and blending this with a polyurethane foam obtained using a condensation polyester polyol, It has been found that the purpose can be achieved. The present invention has been completed based on such findings.

That is, the present invention provides (A) a polyurethane foam obtained by using a condensation polyester polyol as a polyol component, (B) a conductivity imparting agent,
(C) A silicone foam stabilizer and / or polyethylene having a ratio (EO / PO) of 80/20 to 100/0 of oxyethylene units (EO) and oxypropylene units (PO) in the polyether part as a foam stabilizer. An object of the present invention is to provide a conductive elastic member using a conductive material containing a glycol type nonionic surfactant.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the conductive material used for the conductive elastic member of the present invention, the polyurethane foam of the component (A) is obtained by using a condensation polyester polyol as a polyol component. The condensed polyester polyol is not particularly limited, and may be arbitrarily selected from known ones conventionally used for polyurethane elastomers and polyurethane foams. Examples of such condensed polyester polyols include dicarboxylic acids such as adipic acid, glutaric acid, succinic acid, sebacic acid, pimelic acid, and suberic acid, and ethylene glycol; diethylene glycol; 1,4-butanediol; Hexanediol; propylene glycol; those obtained by condensation with diols such as neopentyl glycol and triols such as trimethylolethane and trimethylolpropane. In addition, a polycarbonate polyol such as a polycarbonate diol having a structure in which an alkylene group (for example, a hexylene group) or a xylylene group is arranged in a main chain via a carbonate bond can also be used as the condensation polyester polyol. As these condensation-based polyester polyols, two or more functional groups are contained in one molecule.
Those having four and having a number average molecular weight of 200 to 5000 are preferred.

In the present invention, as the polyol component, one kind of the above-mentioned condensed polyester polyol may be used, or two or more kinds thereof may be used in combination. In addition, other known polyols can be used together if desired, as long as the object of the present invention is not impaired. here,
Other known polyols include, for example, polyether polyols obtained by adding ethylene oxide or propylene oxide to polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin, or polytetramethylene ether glycol obtained by ring-opening polymerization of tetrahydrofuran And the like. Further, lactones such as γ-butyrolactone, δ-valerolactone, and ε-caprolactone can be used in the form of ethylene glycol; diethylene glycol;
4-butanediol; 1.6-hexanediol; lactone-based polyester polyols obtained by ring-opening polymerization in the presence of diols such as propylene glycol and triols such as trimethylolethane and trimethylolpropane; The terminal of the polyether polyol is changed to γ-butyrolactone, δ-valerolactone, ε
And ester-modified polyols modified with lactones such as caprolactone.

As described above, the polyurethane foam as the component (A) used in the present invention may use a condensed polyester polyol as the polyol component, and other conditions in the production are not particularly limited. As the polyurethane foam, any of a soft foam and a hard foam can be used, but a soft foam is preferable. The properties are not particularly limited, and may be appropriately selected according to various situations.

On the other hand, as the polyisocyanate component,
There is no particular limitation, and any known ones conventionally used in the production of polyurethane can be used. Examples of the polyisocyanate component include tolylene diisocyanate, diphenylmethane diisocyanate and hydrogenated products thereof, crude or modified diphenylmethane diisocyanate and hydrogenated products thereof,
Hexamethylene diisocyanate, isophorone diisocyanate and the like can be mentioned. These may be used alone or in combination of two or more.

A chain extender can be used in combination. Examples of the chain extender include short-chain diols such as ethylene glycol; propylene glycol; and 1,4-butanediol; ethylene diamine, tetramethylene diamine, and hexane. Short chain diamines such as methylene diamine and the like can be mentioned. These chain extenders may be used alone or in combination of two or more. The polyurethane foam used in the present invention also includes a crosslinked polyurethane. Various cross-linking methods such as allophanate cross-linking and burette cross-linking are known as cross-linking of polyurethane, and any of these methods can be used.

In the conductive material used for the conductive elastic member of the present invention, a conductivity-imparting agent is used as the component (B). As the conductivity-imparting agent, various conventionally used agents can be used, and there is no particular limitation. Among them, preferred are quaternary ammonium salts. As the quaternary ammonium salt, various ones can be used.

[0015]

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Wherein R ¹ is an alkyl group having 1 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms or an aralkyl group having 7 to 30 carbon atoms, and R ² , R ³ and R ⁴ are each independently represents an alkyl group having 1 to 6 carbon atoms, X ^n-represents an n-valent anion. Here, n may be mentioned compounds represented by is an integer from 1 to 6.). In the general formula (I), the alkyl group having 1 to 30 carbon atoms in R ¹ may be linear, branched or cyclic, and examples thereof include a methyl group, an ethyl group, a propyl group, Butyl, hexyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl and the like. Examples of the aryl group having 6 to 30 carbon atoms include a phenyl group and a naphthyl group.
Examples of the aralkyl group 30 include a benzyl group, a phenethyl group, and a naphthylmethyl group. In addition,
In the above-mentioned aryl group and aralkyl group, a suitable inert group such as a lower alkyl group, a lower alkoxy group and a halogen may be introduced on the carbon ring.

The alkyl group having 1 to 6 carbon atoms represented by R ² , R ³ and R ⁴ may be linear, branched or cyclic, and examples thereof include a methyl group and an ethyl group. Base.
Examples include a propyl group, a butyl group, a pentyl group, a hexyl group, a cyclopentyl group, and a cyclohexyl group. R
² , R ³ and R ⁴ may be the same or different. Further, as X ^n- , for example, F ⁻ , C
l ^-, Br ^-, I ^- halogen ion, NO ₃ ^-, CO
Inorganic acid ions such as ₃ ²⁻ , SO ₄ ²⁻ , ClO ₄ ⁻ , BF ₄ ⁻ etc., acetate (CH ₃ COO ⁻ ), benzoate, malonate, malate, succinate, maleate, fumarate, phthalate Acid radicals, isophthalic acid radicals, terephthalic acid radicals,
Organic acid ions such as trimellitic acid radical, trimesic acid radical, and tricarbamic acid radical, as well as CH ₃ OSO ₃ ⁻ , C
₂ H ₅ OSO ₃ ^-, and sulfur-containing organic acid ion such as p- toluenesulfonic acid radicals are mentioned.

Examples of the quaternary ammonium salt represented by the general formula (I) include tetrabutylammonium chloride, dodecyltrimethylammonium chloride (eg, lauryltrimethylammonium chloride), hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride. (Eg, stearyltrimethylammonium chloride), modified aliphatic dimethylethylammonium ethosulfate, tetraethylammonium perchlorate, tetrabutylammonium perchlorate, tetraethylammonium borofluoride, tetrabutylammonium borofluoride, and further tetraethylammonium, tetrabutylammonium, Benzyltrimethylammonium, dodecyltrimethylammonium (for example, laurylt Quaternary ammonium such as methylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (eg, stearyltrimethylammonium), modified aliphatic dimethylethylammonium, malonic acid, malic acid, succinic acid, maleic acid, fumaric acid, phthalic acid, Examples thereof include salts with polyfunctional acid groups such as isophthalic acid group, terephthalic acid group, trimellitic acid group, trimesic acid group and tricarbaric acid group.

The (B) conductivity-imparting agent may be, if desired, a conventionally used sodium perchlorate, potassium perchlorate, calcium perchlorate or the like as long as the object of the present invention is not impaired. Inorganic salts, conductive carbon black, metal powders, metal oxide powders, and conductive fillers such as whiskers may be used in place of the quaternary ammonium salt or together with the ammonium salt. . The content ratio of the (B) conductivity-imparting agent in the conductive material of the present invention varies depending on various situations such as a desired volume specific resistance value of the material, and cannot be uniquely determined.
Usually, the amount is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the polyurethane foam of the component (A).
A range of 1 to 3 parts by weight is more preferred.

In the conductive material used for the conductive elastic member of the present invention, a foam stabilizer is used as the component (C). Here, as the foam stabilizer, one or both of a silicone foam stabilizer and a polyethylene glycol type nonionic surfactant are used. Here, as the silicone foam stabilizer, the ratio (EO / PO) of oxyethylene units (EO) to oxypropylene units (PO) is 80 /.
20-100 / 0, preferably 90 / 10-100 / 0
And a silicone foam stabilizer having a polyether moiety. That is, this silicone foam stabilizer is a polyether or oxyethylene unit 10 composed of a copolymer containing oxyethylene units and oxypropylene units at a predetermined ratio.
A polyether-modified silicone oil obtained by bonding a polyether composed of a homopolymer (ie, a homopolymer of ethylene oxide) composed of 0% with a silicone oil such as dimethylpolysiloxane. There are various types of such silicone foam stabilizers, for example, the following general formula (II) or (III)

[0021]

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(Wherein R represents hydrogen, methyl, butyl or acetyl, p, q and a, b each represent the number of repetitions of each unit. A / b is 80/20 to
100/0, preferably 90/10 to 100/0) dimethyl polysiloxane polyoxyalkylene copolymer (polyether-modified silicone oil)
Are preferred. Further, at least a part of the methyl group bonded to the silicon atom in the general formula (II) or (III) may be replaced with an alkyl group such as an ethyl group, an allyl group such as a phenyl group, or a chloropropylene group (C ₃ H ₆ Cl), cyanoethylene group (C ₂ H
₄ CN), and compounds substituted with an isopropoxy group (OCH (CH ₃ ) ₂ ).

In general formulas (II) and (III), for convenience, a block copolymer of oxyethylene units (EO) and oxypropylene units (PO) is shown. The oxyethylene unit (EO) and the oxypropylene unit (PO) are copolymerized not only in diblock form but also in triblock form, tetrablock form, polyblock form, and random form. Are also included. In that case, a means the total number of oxyethylene units, and b means the total number of oxypropylene units.
This is the same for p and q.

In the present invention, the above-mentioned silicone foam stabilizer is preferably used. In particular, those having a polyether portion of 100% of oxyethylene units (that is, EO / P
O is 100/0) can be used as a more preferable one. Examples of such silicone foam stabilizers in which the polyether portion comprises only oxyethylene units include, for example, SH193 (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.) and SRX295 (trade name, Toray Dow Corning Silicone ( SZ1605 (trade name, manufactured by Nippon Unicar Co., Ltd.), SZ1642 (trade name, manufactured by Nippon Unicar Co., Ltd.), SZ1654 (trade name,
Commercial products such as Nippon Unicar Co., Ltd., L5420 (trade name, manufactured by Nippon Unicar Co., Ltd.) and L5421 (trade name, manufactured by Nippon Unicar Co., Ltd.) can also be used.

Next, the polyethylene glycol type nonionic surfactant means a nonionic surfactant having a polyoxyethylene chain. This polyethylene glycol type nonionic surfactant is synthesized by adding ethylene oxide to a hydrophobic part or by reacting polyethylene glycol with a carboxylic acid or the like. By changing the molecular weight of the polyethylene glycol to be reacted with an acid or the like, the size of the hydrophilic group (polyoxyethylene chain) can be changed, and the hydrophilicity (HLB value) as a nonionic surfactant can be changed.

According to the knowledge of the present inventors, when a nonionic surfactant is used as a foam stabilizer for urethane foam, the size (length) of the polyoxyethylene chain and the ratio of the polyoxyethylene chain to the total nonionic surfactant are considered. Has an effect on foam control. If the polyoxyethylene chain is short or the amount is small, the foam regulating power is small, and the foam density is not easily reduced. Also, if the polyoxyethylene chain is long or the amount is large, the foam regulating power increases,
The polyoxyethylene chain has high crystallinity, the freezing point of the nonionic surfactant increases, and the workability is impaired due to poor solubility. Therefore, in the present invention, there is no particular limitation, and various polyethylene glycol-type nonionic surfactants can be used, but from the viewpoint of both foam control and workability, a suitable polyethylene glycol-type nonionic surfactant is used. Is more desirable.

Such polyethylene glycol type nonionic surfactants are roughly classified into (i) an alkylphenol EO adduct, (ii) a higher alcohol EO adduct, (iii) a polyhydric alcohol ester EO adduct, and (iv) polyethylene. Glycol monoester and (v) polyethylene glycol diester. Among them, (i) alkylphenol EO adducts include polyoxyethylene nonyl phenyl ether (trade name: Nonipol, manufactured by Sanyo Chemical Industries, Ltd.) and polyoxyethylene octyl phenyl ether (trade name: Octapol, Sanyo Chemical Co., Ltd.) Co., Ltd.), polyoxyethylene dodecyl phenyl ether (trade name: dodecapol, manufactured by Sanyo Chemical Industries, Ltd.)
Examples of (ii) higher alcohol EO adducts include polyoxyethylene lauryl ether (trade name: Emulmin L, manufactured by Sanyo Chemical Industries, Ltd.) and polyoxyethylene cetyl ether (trade name: Emulmin CC, Sanyo Kasei Kogyo Co., Ltd.), polyoxyethylene stearyl ether (trade name: Emulgen 306P, manufactured by Kao Corporation),
Examples include polyoxyethylene oleyl ether (trade name: Emulmin CO, manufactured by Sanyo Chemical Industries, Ltd.), and (i.
ii) As the polyhydric alcohol ester EO adduct, sorbitan monolaurate EO adduct, sorbitan monopalmitate EO adduct, sorbitan monostearate EO
Examples of adducts and sorbitan monooleate EO adducts, and (iv) polyethylene glycol monoesters include polyethylene glycol monostearate (trade name: Ionnet MS, manufactured by Sanyo Chemical Industries, Ltd.), polyethylene monooleate Glycol (trade name: Ionnet MO, manufactured by Sanyo Chemical Industry Co., Ltd.) and the like. (V) As the polyethylene glycol diester, polyethylene glycol dilaurate (trade name: Ionet DL,
Sanyo Kasei Kogyo Co., Ltd.), polyethylene glycol distearate (trade name: Ionnet DS, Sanyo Kasei Kogyo Co., Ltd.), polyethylene glycol monooleate (trade name: Ionet DO, Sanyo Kasei Kogyo Co., Ltd.), etc. Is exemplified.

The foam stabilizer used as the component (C) in the conductive material of the present invention is the above-mentioned silicone foam stabilizer or polyethylene glycol type nonionic surfactant, and these can be used alone. Both can be used in combination, or one of them can be used in combination with another type of foam stabilizer. However, when the silicone foam stabilizer and the polyethylene glycol-type nonionic surfactant are used in combination, the resulting conductive elastic member is more effective in lowering the density and hardness. The content ratio of the foam stabilizer with the above (C) in the conductive material of the present invention may be appropriately selected according to various situations, but usually, the polyol component 10 in the above component (A) is used.
The amount is preferably from 0.5 to 5.0 parts by weight, more preferably from 1.0 to 10 parts by weight, based on 0 parts by weight.

Next, the method for producing the conductive material used in the present invention is not particularly limited, and may be a conventional method. An example is as follows. First, the above-mentioned condensed polyester polyol component, polyisocyanate component, conductivity-imparting agent and the above foam stabilizer, optionally a chain extender, catalyst, reinforcing agent, coloring agent, and other foam stabilizers are homogeneously mixed. After that, the mixture is heated to cause reaction hardening and foaming (so-called one-shot method), thereby obtaining a desired low-density and low-hardness conductive material. Further, the condensation-based polyester polyol component is isocyanated in advance with a polyisocyanate component, and this is combined with a conductivity-imparting agent and the above-mentioned foam stabilizer, a chain extender optionally used, a catalyst, a reinforcing agent, a coloring agent, After uniformly mixing another foam stabilizer and the like, the mixture may be heated to cause reaction hardening and foaming (so-called prepoly method).

As for the foaming method, a method of mixing bubbles by mechanical stirring (ie, a mechanical floss method)
However, a desired low-density and low-hardness conductive material can also be obtained by a method using a foaming agent such as water, chlorofluorocarbon, alternative fluorocarbon, or cyclopentane. Here, the standard of low density and low hardness varies depending on the purpose of use and the like, but the roller hardness is usually 20 to 50 degrees in Asker C hardness, preferably 25 degrees.
~ 45 degrees and the foam density is 0.70 g / cm
^{A value of 3} or less, preferably 0.60 g / cm ³ or less, is advantageous because a roller having the above hardness range can be easily produced. The expansion ratio may be appropriately determined and is not particularly limited.

The method of manufacturing a desired conductive elastic member using the conductive material obtained in this manner is not particularly limited, and various known methods may be used. For example, a core metal such as plated iron or stainless steel is coated with the conductive material, and the outside thereof is coated with a conductive, semi-conductive, or insulating paint according to the intended use, thereby achieving a desired comparison. A conductive elastic member having a low target roller hardness can be obtained. The shape of the conductive elastic member of the present invention is not particularly limited, and may be determined according to the application.
Examples include a plate shape, a square block shape, a spherical shape, a brush shape, and the like, and usually a roller shape or a plate shape.

Next, an example in which the conductive elastic member of the present invention is used as a transfer roller of an electrophotographic copying machine will be described.
FIG. 1 is an explanatory view showing an example of a transfer device of an electrophotographic copying machine using the conductive elastic member of the present invention, which is composed of a conductive elastic member of the present invention provided with a metal core (not shown). A conductive roller (transfer roller) 1 is brought into contact with a toner image carrier 2 such as a photosensitive drum via a transfer material 4 such as paper, so that the conductive roller 1 and the toner image carrier 2 A voltage is applied from the power supply 3 to generate an electric field between the toner image carrier and the conductive roller, thereby transferring the toner on the toner image carrier 2 to the transfer material 4.

[0033]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 Adipic acid, diethylene glycol and triol (Polylite OD-X-106 manufactured by Dainippon Ink and Chemicals, Inc.)
(Trade name)) number average molecular weight 220 obtained by condensation
0, 100 parts by weight of a condensed polyester polyol having 2.3 functional groups in one molecule, 18.1 parts by weight of modified diphenylmethane diisocyanate, and a silicone surfactant having an EO / PO ratio of 100/0 in the polyether part (trade name) : SH
193, manufactured by Dow Corning Toray Silicone Co., Ltd.)
4.0 parts by weight, 8.0 parts by weight of polyoxyethylene nonylphenyl ether having 20 moles of EO added, 0.016 parts by weight of dibutyltin dilaurate, and modified aliphatic dimethylethylammonium ethosulfate [H (CH ₂ )
_4-20 C ₂ H ₅ N (CH ₃ ) ₂ C ₂ H ₅ OSO ₃ , molecular weight 4
66-550] 0.15 parts by weight were mixed with a mixer, and a polyurethane foam transfer roller having a diameter of 16.5 mm and a length of 215 mm, centered on a metal shaft having a diameter of 6 mm, was prepared using the mixture.

The foam density of the produced roller was 0.534.
g / cm ³ , Asker C hardness is 32 degrees, which is equivalent to that of a polyether polyol-based compound (see Comparative Example 1 described later), and has a hardness that can be used as a roller requiring low hardness such as a transfer roller. I was Next, the transfer roller was placed on an aluminum plate having a thickness of 5 mm, and the both ends of the roller were pressed against each other with a force of 500 g.
The electric resistance between the core metal and the copper plate of the resistance measuring instrument at 00 V was measured. The temperature at the time of measurement was 20 ° C., and the humidity was 50 ° C. The electric resistance is 5. when the applied voltage is 1000 V.
It was 46 × 10 ⁷ Ω (10 ^7.74 Ω).

Further, the transfer roller was placed in an ozone tester manufactured by Suga Test Machine and left at room temperature for 72 hours at an ozone concentration of 7 ppm. After standing, there was no change in the appearance of the roller taken out of the ozone tester, and the Asker C hardness was 31 degrees, which was almost equal to the initial hardness. Next, when the roller resistance of this roller was measured in the same manner as described above, the applied voltage was 10 at a temperature of 20 ° C. and a humidity of 50 ° C.
At the time of 00V, it was 3.55 × 10 ⁷ Ω (10 ^7.55 Ω). Further, the transfer roller was incorporated in the transfer device of the image forming apparatus (electrophotographic copying machine) shown in FIG.
When a gray scale, solid black, and solid white image was printed in an environment at a temperature of 10 ° C. and a humidity of 10%, a good image was obtained. When a grayscale, black solid, and white solid image was printed in an environment of a temperature of 32.5 ° C. and a humidity of 85%,
Good images were obtained.

On the other hand, the raw materials prepared according to the same formulation as described above are placed in a closed container, and the pressure in the container is reduced by a vacuum pump.
After stirring and mixing the raw materials while defoaming, the mixed and stirred raw materials were poured into a mold and heated and cured to produce an elastomer sheet having a thickness of 1 mm. A sample for a tensile test was punched out of this sheet with a damper for a tensile test (width of a parallel portion: 4 mm; marked line distance: 10 mm), and a tensile test was performed at a tensile speed of 300 mm / min. 0.2 kg / cm ² , elongation 224%,
A result was obtained that the strength was higher than the strength of the test sample (see Comparative Example 1 described later) by the polyether polyol-based formulation prepared in the same manner.

Comparative Example 1 A polyether polyol having an average molecular weight of 3,500 and a number of functional groups of 3 per molecule obtained by polymerizing propylene oxide and ethylene oxide on glycerin was 100 parts by weight,
14.2 parts by weight of modified diphenylmethane diisocyanate,
4.0 parts by weight of a silicone surfactant having an EO / PO ratio of 70/30 in the polyether part (trade name: SF2935F, manufactured by Dow Corning Toray Silicone Co., Ltd.), 0.03 parts by weight of dibutyltin dilaurate, and Modified aliphatic dimethylethylammonium ethosulfate [H (CH ₂ )
_4-20 C ₂ H ₅ N (CH ₃ ) ₂ C ₂ H ₅ OSO ₃ , molecular weight 4
66-550] 0.15 parts by weight were mixed with a mixer, and a polyurethane foam transfer roller having a diameter of 16.5 mm and a length of 215 mm, centered on a metal shaft having a diameter of 6 mm, was prepared using the mixture.

The foam density of the produced roller was 0.441.
g / cm ³ , Asker C hardness was 31 degrees, and had a hardness that could be used as a roller requiring low hardness such as a transfer roller. Next, the transfer roller was moved to a thickness of
Place the roller on an aluminum plate.
The electrical resistance between the cored bar and the copper plate of the resistance measuring device at an applied voltage of 1000 V was measured while being pressed against each other with a force of 0 g.
The temperature at the time of measurement was 20 ° C., and the humidity was 50 ° C. The electric resistance is 8.91 × 10 ⁷ Ω when the applied voltage is 1000 V.
(10 ^7.95 Ω).

Further, the transfer roller was placed in an ozone tester manufactured by Suga Test Machine and left at room temperature at an ozone concentration of 7 ppm for 72 hours. After standing, the roller removed from the ozone tester had a sticky surface and was different from before the ozone test. The Asker C hardness was 28 degrees, which was lower than the initial hardness. Then, when the roller resistance of this roller was measured in the same manner as described above, it was 4.68 × 10 ⁷ Ω (10 ^7.67 Ω) when the applied voltage was 1000 V at a temperature of 20 ° C. and a humidity of 50 ° C. Further, the transfer roller was incorporated in the transfer device of the image forming apparatus (electrophotographic copying machine) shown in FIG.
When a gray scale, solid black, and solid white image was printed in an environment of 0%, the photosensitive member was contaminated, and a good image was not obtained.

On the other hand, the raw materials prepared according to the same formulation as described above are placed in a closed container, and the pressure in the container is reduced by a vacuum pump.
After stirring and mixing the raw materials while defoaming, the mixed and stirred raw materials were poured into a mold and heated and cured to produce an elastomer sheet having a thickness of 1 mm. As in Example 1, a sample for a tensile test was punched out from this sheet with a damper for a tensile test, and a tensile test was performed. The tensile strength was 19.7 kg / cm ² and the elongation was 173%. The strength was lower than the strength of the test sample (see the above-mentioned Example 1) by the condensed polyester polyol-based composition prepared as described above.

Comparative Example 2 Adipic acid, diethylene glycol and triol (Polylite OD-X-106, manufactured by Dainippon Ink and Chemicals, Inc.)
(Trade name)) number average molecular weight 220 obtained by condensation
0, 100 parts by weight of a condensed polyester polyol having 2.3 functional groups in one molecule, 16.3 parts by weight of modified diphenylmethane diisocyanate, and a silicone surfactant having an EO / PO ratio of 70/30 in the polyether part (trade name) : SF
2935F, Dow Corning Toray Silicone Co., Ltd.
4.0 parts by weight, 0.016 parts by weight of dibutyltin dilaurate and modified aliphatic dimethylethylammonium ethosulfate [H (CH ₂ ) _4-20 C ₂ H ₅ N (CH ₃ ) ₂ C ₂
H ₅ OSO _3, molecular weight 466-550] 0.15 parts by weight in a mixer, with the mixture, diameter 16.5mm, which is disposed around the metal shaft having a diameter of 6 mm, polyurethane foam length 215mm A transfer roller was manufactured.

The foam density of the produced roller was 0.694.
g / cm ³ , Asker C hardness is 56 degrees, and a polyether polyol-based formulation (see Comparative Example 1 described above) or a condensation-based polyester polyol-based formulation using a foam stabilizer effective in lowering the density and hardness ( (See Example 1 described above), and had a hardness that could not be used as a roller requiring low hardness such as a transfer roller. Next, the transfer roller is placed on a 5 mm-thick aluminum plate, and while the both ends of the roller are pressed against each other with a force of 500 g, the electric resistance between the core metal and the copper plate of the resistance measuring device at an applied voltage of 1000 V is measured. did. The temperature at the time of measurement was 20 ° C., and the humidity was 50 ° C. The electric resistance was 5.13 × 10 ⁷ Ω (10 ^7.71 Ω) when the applied voltage was 1000 V.

Further, the transfer roller was placed in an ozone tester manufactured by Suga Test Machine and left at room temperature for 72 hours at an ozone concentration of 7 ppm. After standing, there was no change in the appearance of the roller taken out of the ozone tester, and the Asker C hardness was 55 degrees, which was almost equal to the initial hardness. Next, when the roller resistance of this roller was measured in the same manner as described above, the applied voltage was 10 at a temperature of 20 ° C. and a humidity of 50 ° C.
It was 4.17 × 10 ⁷ Ω (10 ^7.62 Ω) at 00V. Further, the transfer roller was incorporated in the transfer device of the image forming apparatus (electrophotographic copying machine) shown in FIG.
When a gray scale, black solid, or white solid image was printed in an environment of 10 ° C. and a humidity of 10%, a good image could not be obtained because the roller hardness was too high.

On the other hand, the raw materials prepared according to the same formulation as described above are placed in a closed container, and the pressure in the container is reduced by a vacuum pump.
After stirring and mixing the raw materials while defoaming, the mixed and stirred raw materials were poured into a mold and heated and cured to produce an elastomer sheet having a thickness of 1 mm. As in Example 1, a sample for a tensile test was punched out from this sheet with a damper for a tensile test, and a tensile test was performed. As a result, the tensile strength was 37.2 kg / cm ² and the elongation was 237%. The strength was higher than the strength of the test sample (see Comparative Example 1 described above) based on the polyether polyol-based compound prepared as described above.

[0045]

The conductive elastic member of the present invention is excellent in ozone resistance, has sufficient mechanical strength even when manufactured by the one-shot method, and has relatively low hardness. Therefore, the conductive elastic member of the present invention is extremely suitable as a transfer roller or the like in an electrophotographic apparatus. Further, it is suitably used as an intermediate transfer drum, a developing roller and a developer supply roller.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a transfer device of an electrophotographic copying machine using a conductive elastic member of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive roller 2 toner image carrier (photoconductor) 3 power supply 4 transfer material (recording medium)

Claims (3)

[Claims] 1. A polyurethane foam obtained by using (A) a condensation-based polyester polyol as a polyol component, (B) a conductivity imparting agent, and (C) an oxyethylene unit of a polyether portion as a foam stabilizer ( EO) and the ratio (EO / PO) of oxypropylene units (PO) is 80
A conductive elastic member comprising a conductive material containing a silicone foam stabilizer and / or a polyethylene glycol type nonionic surfactant having a ratio of / 20 to 100/0. 2. The conductive elastic member according to claim 1, wherein the roller hardness of the conductive elastic member is 20 to 50 degrees as Asker C hardness. 3. The conductive elastic member according to claim 1, wherein the conductive elastic member is used as a transfer roller, an intermediate transfer drum, a developing roller, or a developer supply roller in an electrophotographic apparatus.