JP2002053639A - Conductive elastic member and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive elastic member having excellent characteristics such as low electric resistance, low hardness, micro cells, low residual strain of compression, high strength or the like. SOLUTION: This conductive elastic member comprising polyurethane foam obtained by mixing a urethane prepolymer synthesized from a polyol and a polyisocyanate and a water dispersed carbon, uses (A) a polymer polyol synthesized by using a polyether polyol including >=70 wt.% of oxypropylene unit as a base, (B) a hydrophilic polyether polyol including >=50 wt.% of oxyethylene unit or jointly using (C) a polyether polyoi including >=70 wt.% of oxypropylene unit, and an image forming device.

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 used in an image forming apparatus such as an electrophotographic apparatus, an electrostatic recording apparatus, and a toner flying recording apparatus, and more particularly, to a low electric resistance and a low hardness. The present invention relates to a conductive elastic member having excellent characteristics such as fine cells, low compression residual strain, and high strength, and an image forming apparatus equipped with the conductive elastic member.

[0002]

2. Description of the Related Art In recent years, with the advance of electrophotographic technology, a medium resistance elastic roller has attracted attention as a transfer member, a toner supply member, a charging member and the like of a dry electrophotographic apparatus. Used for rollers, charging rollers, and the like. As a material for forming the medium resistance elastic roller, a polymer elastomer or a polymer foam having rubber elasticity has been used. Conventionally,
The members used for such purposes include, for example, conductive carbon such as carbon black, metal oxides, NBR, EPDM, and the like provided with conductivity by an ionic conductive agent.
There are elastomers and foams such as silicone rubber and polyurethane. Among these, the polyurethane material is a low-hardness member suitable for the above-mentioned conductive member, and a low-hardness foam is obtained by a method using a foaming agent such as water and a low-boiling compound, a method using mechanical stirring, and the like. Can be
It is preferably used for the above members. The hardness of the polyurethane foam can also be reduced by selecting the raw materials that determine the chemical structure of the polyurethane and the amount of the raw materials that determine the chemical structure. When a polyurethane foam is used for a toner supply roller or the like, it is required to have a low hardness, a low resistance, a fine cell, a low compression set, a high tensile strength, and a low cost. You. When imparting conductivity to a polyurethane foam, the addition of an ionic conductive agent does not sufficiently lower the electrical resistance of the polyurethane foam, so that a large amount of conductive carbon must be added. However, when a large amount of conductive carbon is added to the polyol, isocyanate, prepolymer, or the like, which is a raw material of the polyurethane foam, the viscosity of the raw material in which the conductive carbon is dispersed increases, so that the raw material can be sufficiently mixed and stirred. There were problems such as that the cell of the obtained polyurethane foam was coarse and that the electrical resistance was difficult to decrease.

In order to solve such problems, a method has been proposed in which a water-dispersible carbon, a catalyst, a foam stabilizer and the like are mixed with a urethane prepolymer to produce a conductive polyurethane foam by a water foaming method. I have. Examples of such a production method include, for example, a hydrophilic prepolymer obtained by reacting a polyoxyethylene-polyoxypropylene copolymerized polyether polyol having a polyoxyethylene content of 60 to 100% by weight with isocyanate; A method has been proposed in which an aqueous dispersion containing conductive carbon fine particles is mixed and reacted in a stoichiometrically excess condition with water (JP-A-49-69794, JP-B-61-2086). The conductive polyurethane foam obtained by this method has a low resistance and a fine cell, but has problems such as the foam easily shrinking after foaming and a large compression set. Further, an aqueous dispersion containing conductive carbon fine particles and a hydrophilic prepolymer obtained by reacting an oxyethylene-oxypropylene copolymerized polyether polyol having a polyoxyethylene content of 30% by weight or less with an isocyanate is subjected to a chemical equivalent. A method of causing a mixing reaction under a water excess condition has been proposed (JP-A-2-228357, JP-A-10-251426). In this method, there are problems that the cells are large when free foaming is performed under the atmospheric pressure, and the foam is easily cracked and the cells are roughened.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the conventional conductive elastic member and provides excellent characteristics such as low electric resistance, low hardness, fine cells, low compression set, and high strength. It is an object of the present invention to provide a conductive elastic member made of a polyurethane foam.

[0005]

Means for Solving the Problems The present inventors have found that a urethane prepolymer synthesized from a polyol and a polyisocyanate, and water-dispersed carbon are mixed with stirring to produce a polyurethane foam by water foaming. As a result of intensive studies on a method for producing a polyurethane foam having a polyether, a specific polymer polyol and a specific hydrophilic polyether polyol are used in combination as a polyol, or a polyether having a large content of oxypropylene units in these. By using a polyol together, it has been found that a conductive elastic member made of polyurethane foam having the above-mentioned excellent properties can be obtained. That is, when using a hydrophilic polyol alone, the cells of the polyurethane foam become fine, but since the hydrophilic polyol having a large number of polyoxyethylene chains has a high activity, the number of closed cells in the polyurethane foam increases, and when the foam is free-foamed, Normal polyurethane foam without shrinkage cannot be obtained. The present inventors have conducted various studies on a method for obtaining an appropriate polyurethane foam without shrinkage by free foaming while maintaining the fine cells of the polyurethane foam when using a hydrophilic polyol. By using in combination with a hydrophilic polyol, it has uniform and fine cells, is a closed cell,
It has been found that a polyurethane foam that does not shrink can be obtained, and a polyurethane foam having more excellent properties can be obtained by further using a specific polyether polyol in combination.A conductive elastic member made of such a polyurethane foam can be used for image formation. It has been found that it is suitable as a member to be attached to the device. The present invention has been completed based on such findings.

That is, the present invention relates to a conductive elastic member made of a polyurethane foam obtained by stirring and mixing a urethane prepolymer synthesized from a polyol and a polyisocyanate, and water-dispersed carbon; A polymer polyol synthesized on the basis of a polyether polyol containing 70% by weight or more of the oxyethylene unit (B)
50% by weight of a polymer polyol synthesized in combination with a hydrophilic polyether polyol containing at least 70% by weight of (A) a polyether polyol containing at least 70% by weight of an oxypropylene unit and (B) an oxyethylene unit containing at least 70% by weight of an oxyethylene unit. A conductive elastic member comprising a combination of the above-mentioned hydrophilic polyether polyol and a polyether polyol containing (C) an oxypropylene unit of 70% by weight or more, and an image forming apparatus equipped with the conductive member Is provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a polymer polyol (A) is a polymer polyol synthesized on the basis of a polyether polyol containing at least 70% by weight of oxypropylene units. For example, polymer particles obtained by polymerizing a monomer having an ethylenic double bond, preferably a monomer such as acrylonitrile or styrene, are dispersed in a polyether polyol. In the polymer polyol (A), the content of oxypropylene units is 7
It is preferably from 0 to 100% by weight, particularly preferably from 80 to 100% by weight. The polyether polyol is obtained by addition polymerization of propylene oxide and ethylene oxide to an initiator such as glycerin, trimethylolpropane, ethylene glycol, propylene glycol, pentaerythritol, and sorbitol.
The polymer polyol (A) has 2 to 6 functional groups, particularly
Those having a weight average molecular weight of from 2,000 to 4,000, particularly from 2,500 to 5,000 are preferably used. The polymer component (solid content) contained in the polymer polyol is preferably 15 to 45% by weight, particularly preferably 20 to 40% by weight. As a monomer constituting the polymer, for example, a monomer having an ethylenic double bond, specifically, acrylonitrile or styrene is preferably mentioned, and in addition, melamine and the like can be mentioned.
As the polymer component, an acrylonitrile homopolymer or a copolymer of acrylonitrile and styrene is preferable. The hydrophilic polyether polyol (B) is a hydrophilic polyether polyol containing 50% by weight or more of oxyethylene units, and includes glycerin, trimethylolpropane, ethylene glycol, propylene glycol,
It is obtained by adding propylene oxide and ethylene oxide to an initiator such as pentaerythritol and sorbitol. In the hydrophilic polyether polyol (B), the content of the oxyethylene unit is preferably 50% by weight or more. The hydrophilic polyether polyol (B) has a functional group number of 2 to 6, particularly 2.5 to 4, and a weight average molecular weight of 1500 to 6000, particularly 2500 to 5000.
Is preferably used. The polyether polyol (C) is a polyether polyol containing oxypropylene units in an amount of 70% by weight or more. Propylene oxide and ethylene oxide are used as initiators such as glycerin, trimethylolpropane, ethylene glycol, propylene glycol, pentaerythritol, and sorbitol. Is subjected to addition polymerization. In the polyether polyol (C), the content of oxypropylene units is 80
It is particularly preferable that the content be from 100 to 100% by weight. The polyether polyol (C) has a functional group number of 2 to 6, especially 2.5 to 5.
4, weight average molecular weight of 1500 to 6000, especially 250
Those having 0 to 5000 are preferably used.

By changing the mixing ratio of the above polymer polyol (A), hydrophilic polyether polyol (B) and polyether polyol (C), polyurethane foams having various hardnesses can be obtained. Polymer polyol (A) and hydrophilic polyether polyol (B)
The mixing ratio of the polyether polyol (C) and the polyether polyol (C) is preferably from 3 to 4 in terms of reducing the compression set of the polyurethane foam and reducing the dimensional change.
80% by weight, hydrophilic polyether polyol (B) 20
-60% by weight and polyether polyol (C) 0-6
It is preferably 0% by weight. If the amount of the polymer polyol (A) is too large, the hardness of the polyurethane foam becomes too high. On the other hand, if the blending amount of the polymer polyol (A) is too small, communication of the foam is not promoted, and the foam after foaming tends to shrink. If the amount of the hydrophilic polyether polyol (B) is too large, the compression set of the polyurethane foam increases,
In addition, dimensional changes due to environmental conditions increase. If the amount of the hydrophilic polyether polyol (B) is too small, the cells of the polyurethane foam become large, which is unsuitable for conductive members requiring fine cells. If the blending amount of the polyether polyol (C) is too large, there is a disadvantage that the cell diameter becomes large. In the present invention, when the polymer polyol (A) and the hydrophilic polyether polyol (B) are used in combination, the polymer polyol (A)
It is particularly preferred that the content be 60 to 75% by weight and the hydrophilic polyether polyol (B) be 25 to 40% by weight. When the polymer polyol (A), the hydrophilic polyether polyol (B) and the polyether polyol (C) are used in combination, the polymer polyol (A) has a content of 30 to 75% by weight and the hydrophilic polyether polyol (B) has a content of 25 to 75%. 40% by weight, polyether polyol (C) 10 to 30% by weight
It is particularly preferred that When the polyol (C) is used in combination, there is an advantage that it is easier to obtain the desired hardness, the number of cells, the electric resistance, the residual compression set, and the tensile strength.

As the polyol used in the synthesis of the prepolymer according to the present invention, if necessary, polyether polyols, polyester polyols, polyisoprene polyols, polybutadiene polyols, hydrogenated polybutadiene polyols and the like other than the above three kinds of polyols may be used. Can be appropriately used in a range that does not hinder the effect of the above.
Examples of the polyether polyol include polytetramethylene glycol, polyethylene glycol, propanediol, butanediol, and the like. Examples of the polyester polyol include a condensation-based polyester polyol obtained by condensation of a dicarboxylic acid and a diol or a triol, a lactone-based polyester polyol obtained by ring-opening polymerization of a lactone based on a diol or a triol, and a lactone terminated with a lactone. And an ester-modified polyol modified with an ester.

The polyisocyanate used in the synthesis of the prepolymer according to the present invention includes tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude diphenylmethane diisocyanate (crude MDI), isophorone diisocyanate, hydrogenated diphenylmethane isocyanate as isocyanate components. Polyisocyanates having no unsaturated bond, such as naphthalate, hydrogenated tolylene diisocyanate, hexamethylene diisocyanate, and modified isocyanurates thereof;
Modified products such as carbodiimide modified products and glycol modified products are preferably used. Particularly preferred is TDI-8 in which the ratio of 2,4-tolylene diisocyanate to 2,6-tolylene diisocyanate is 80/20 by weight.
0. The NCO group (isocyanate group) content of the prepolymer according to the present invention is preferably 3 to 30% by weight, particularly preferably 5 to 15% by weight.

The water-dispersed carbon used in the present invention is obtained by dispersing carbon black in water by adding a surfactant or a coupling agent, or by treating the surface of carbon black. Those containing from 40 to 40% by weight, particularly from 5 to 20% by weight are preferably used. Examples of carbon black include gas black such as electrified black, Ketjen black, and acetylene black, oil furnace black including ink black,
Thermal black, channel black, lamp black and the like. The chemical equivalent ratio of the NCO group / OH group of water contained in the urethane prepolymer and the water-dispersed carbon is preferably 1/100 to 1/2, and 2/1.
00 to 100/100 is particularly preferred. In the present invention, a foam stabilizer is added during the stirring and mixing of the urethane prepolymer and the water-dispersed carbon in order to stabilize the cells of the polyurethane foam. As the foam stabilizer, a polyether-modified silicone foam stabilizer is preferred, and those containing 55% by weight or more, especially 60% by weight or more of oxyethylene units in the polyether portion are preferred. The amount of the silicone foam stabilizer is from 1 to 5 based on 100 parts by weight of the urethane prepolymer.
It is preferable that the amount be from 2 to 3 parts by weight, particularly 2 to 3 parts by weight.

Examples of the catalyst for curing the foam include monoamines such as triethylamine and dimethylcyclohexylamine, diamines such as tetramethylethylenediamine, tetramethylpropanediamine and tetramethylhexanediamine, pentamethyldiethylenetriamine and pentamethyldipropylene. Triamine,
Triamines such as tetramethylguanidine, cyclic amines such as triethylenediamine, dimethylpiperazine, methylethylpiperazine, methylmorpholine, dimethylaminoethylmorpholine, dimethylimidazole, dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methyl Alcohol amines such as hydroxyethylpiperazine, hydroxyethylmorpholine, bis (dimethylaminoethyl) ether, ethylene glycol bis (dimethyl)
Ether amines such as aminopropyl ether, stannas octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin marker, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin marker, dioctyltin thiocarboxylate, phenylmercurypropion And organometallic compounds such as lead octenoate. Of these, organotin catalysts are particularly preferred. These catalysts may be used alone or in combination of two or more. In the present invention, if necessary, other additives such as a flame retardant, a punching / cutting processability improving agent, an organic filler, and an inorganic filler can be added during the stirring and mixing.

The conductive elastic member of the present invention can be formed into various shapes. When the conductive elastic member is formed into a roller shape, the logarithmic value of the roller resistance (Ω) is 3.0 to 6.0 [logΩ].
In particular, 3.5 to 5.5 [log Ω], the Asker F hardness of the roller is 40 to 85 degrees, particularly 40 to 70 degrees, and more preferably 45 to 65 degrees.
The number of cells per 25 mm of the polyurethane foam is 50 to 200, particularly 50 to 120, and more preferably 60 to 1
One having a compression set of 1 to 10%, particularly 1 to 5%, and a tensile strength of 0.15 to 0.5 MPa is preferably used. The density of the polyurethane foam is 0.05 to 0.2.
g / cm ³ , particularly 0.09 to 0.15 g / cm ³
Is preferred. Although the conductive elastic member of the present invention can be used for various applications, it can be particularly suitably used as a developer supply member or a transfer member of an image forming apparatus. When these are formed in a roller shape, a form in which a polyurethane foam is formed around a metal shaft can be used. As the metal shaft, a steel shaft such as sulfur free-cutting steel plated with zinc or the like, or a shaft made of aluminum, stainless steel, phosphor bronze, or the like can be used.

[0014]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, about the roller etc. obtained by the Example and the comparative example, the characteristic test was performed as follows. (1) Density The value was obtained by dividing the weight of the polyurethane foam in the air by the volume. (2) Number of cells Using a CCD video camera manufactured by Hilox Co., Ltd.
Photographs are taken at a magnification of 0 to 60 times, and the number of cells in the image is set to J.
It was measured in accordance with IS K6402. (3) Compression residual strain Measured according to JIS K 6382. (4) Tensile strength Measured according to JIS K6301. (5) Roller resistance A load of 100 g was applied to both ends of the roller to be tested and pressed against a copper plate, and a resistance value was measured by applying a voltage of 100 V using a resistivity meter R8340A (manufactured by Advantest).

Example 1 A weight average molecular weight of 5 obtained by adding 15% by weight of ethylene oxide and 85% by weight of propylene oxide to glycerin.
Solid content based on polyether polyol of 000 (acrylonitrile, styrene polymer)
20 weight parts of a polymer polyol of about 28 weight%, 75 weight% of ethylene oxide and 25 weight% of propylene oxide added to glycerin, weight average molecular weight 3400
40 parts by weight of a hydrophilic polyether polyol which is a glycerin and 15% by weight of ethylene oxide and 85% by weight of propylene oxide, and a weight average molecular weight of 480.
After weighing out 40 parts by weight of polyether polyol (0) and 21 parts by weight of tolylene diisocyanate (TDI-80) into a sealable container, closing the container lid and shaking the container to thoroughly mix the contents, C. in a hot-air circulation oven. Occasionally, the container was removed from the oven, shaken, and heated for 48 hours while mixing the contents. The NCO content of the prepolymer synthesized in this way was 6.0% by weight. Next, bis- (dimethyl) as a catalyst was added to 27 parts by weight of water-dispersed carbon containing conductive carbon [Lion paste W311N, manufactured by Lion Corporation, carbon content 8% by weight] based on 100 parts by weight of the prepolymer. Aminoethyl) -ether in a 70% by weight dipropylene glycol solution [Kaolyser N, manufactured by Kao Corporation]
o. 12] A mixture of 0.1 part by weight and 2.5 parts by weight of a reactive silicone foam stabilizer comprising polyoxyethylene containing 70% by weight of an ether chain (total 29.6 parts by weight) was mixed with a high-speed mixer. , The mixture is 300 mm x 150 mm
Pour into a free foaming box without lid of × 50mm, and after foaming 1
This was cured at 00 ° C. for 15 minutes to produce a conductive polyurethane foam. This foam was cut into a size of 28 mm x 28 mm x 240 mm using a vertical cutter, and a hole having a diameter of 5.0 mm was formed in the center of the 28 mm x 28 mm surface perpendicularly to this surface. Was wound around the surface and a zinc-plated sulfur free-cutting steel shaft having a diameter of 6.0 mm was inserted therein, and heated in a hot air circulating oven at 120 ° C. for 70 minutes to bond the polyurethane foam and the shaft. Polish this polyurethane foam with shaft with a grinder,
Furthermore, the end of the polyurethane foam is cut, and the outer diameter is 13.
4mm, length 217mm (polyurethane foam part)
Was produced. The density of the polyurethane foam part of this conductive roller is 0.1
06 g / cm ³ , the number of cells is 112 cells / 25 mm, the compression set is 3.8%, the tensile strength is 0.162 MPa, 20 ° C.,
The roller resistance at 50% RH was ^104.40 Ω, and the Asker F hardness of the roller was 50 degrees, indicating that the roller had suitable characteristics. This conductive roller is incorporated in a dry electrophotographic apparatus as a toner supply roller, and is operated under low temperature and low humidity conditions (15 ° C., 1
0%) and high-temperature and high-humidity conditions (32.5 ° C., 85%) for 48 hours, respectively, and then a solid white image and a solid black image were printed. As a result, good images were obtained.

Example 2 A weight average molecular weight of 5 obtained by adding 15% by weight of ethylene oxide and 85% by weight of propylene oxide to glycerin.
Solid content based on polyether polyol of 000 (acrylonitrile, styrene polymer)
40 weight parts of a polymer polyol of about 28 weight%, 75 weight% of ethylene oxide and 25 weight% of propylene oxide added to glycerin, and a weight average molecular weight of 3400
60 parts by weight of a hydrophilic polyether polyol and 21 parts by weight of tolylene diisocyanate (TDI-80) are weighed into a sealable container, the container is closed, and the container is shaken to thoroughly mix the contents. It was placed in a hot air circulating oven at 60 ° C. Occasionally, the container was removed from the oven, shaken, and heated for 48 hours while mixing the contents. The NCO content of the prepolymer synthesized in this way is 6.
It was 0% by weight. Next, bis- (dimethyl) as a catalyst was added to 27 parts by weight of water-dispersed carbon containing conductive carbon [Lion paste W311N, manufactured by Lion Corporation, carbon content 8% by weight] based on 100 parts by weight of the prepolymer. Aminoethyl) -ether in a 70% by weight dipropylene glycol solution [Kaorizer No. 12] 0.1 part by weight, 70% by weight of ether chain
Reactive silicone foam stabilizer consisting of polyoxyethylene
A mixture obtained by dissolving 2.5 parts by weight (total 29.6 parts by weight) was mixed with a high-speed mixer, and the mixture was mixed with a 300 mm × 15.
It was poured into a free foaming box of 0 mm × 50 mm without a lid, and after foaming, was cured at 100 ° C. for 15 minutes to produce a conductive polyurethane foam. This foam was processed in the same manner as in Example 1 to produce a polyurethane foam conductive roller having an outer diameter of 13.4 mm and a length of 217 mm (polyurethane foam portion). The density of the polyurethane foam portion of this conductive roller was 0.073 g / cm ³ , and the number of cells was 1
17 pieces / 25mm, compression set is 6.8%, tensile strength is
0.173MPa, 20 ℃, roller resistance at 50% RH is 10 ^4.80 Omega, Asker F hardness of the roller is 33 degrees,
It had suitable characteristics. This conductive roller is incorporated into a dry electrophotographic apparatus as a toner supply roller,
Low temperature and low humidity conditions (15 ° C, 10%) and high temperature and high humidity conditions (3
(2.5 ° C., 85%) for 48 hours, and then a solid white image and a solid black image were printed. As a result, good images were obtained.

Example 3 Using the same mixture as in Example 1, a conductive polyurethane foam was produced by a pressure molding method. That is, as the pressure mold, a rubber packing is used in a portion where the upper mold and the lower mold are rubbed, and there is no vent hole, and an aluminum mold having an inner dimension of 50 mm × 50 mm × 300 mm is used. It was poured into a pressure mold and cured at 100 ° C. for 15 minutes to produce a conductive polyurethane foam. This foam was processed in the same manner as in Example 1 to produce a polyurethane foam conductive roller having an outer diameter of 13.4 mm and a length of 217 mm (polyurethane foam portion). The density of the polyurethane foam portion of this conductive roller is 1.36 g / cm ³ , and the number of cells is 15
5 pieces / 25mm, compressive residual strain 8.7%, tensile strength 0.
The roller resistance at 192 MPa, 20 ° C. and 50% RH is 1
0 ^4.23 Omega, Asker F hardness of the roller was 74 degrees, had a favorable properties. This conductive roller is incorporated in a dry electrophotographic apparatus as a toner supply roller, and is subjected to low temperature and low humidity conditions (15 ° C., 10%) and high temperature and high humidity conditions (32.
(5 ° C., 85%) for 48 hours.
When a solid white image and a solid black image were printed, good images were obtained. Example 4 Using the same mixture as in Example 2, a conductive polyurethane foam was produced by a pressure molding method in the same manner as in Example 3. This foam was processed in the same manner as in Example 1 to produce a polyurethane foam conductive roller having an outer diameter of 13.4 mm and a length of 217 mm (polyurethane foam portion). The density of the polyurethane foam portion of this conductive roller was 1.07 g / cm ³ , the number of cells was 183 cells / 25 mm, the residual compression set was 9.2%, the tensile strength was 0.204 MPa, and 20.
The roller resistance at 10 ° C. and 50% RH was 10 ^4.58 Ω, and the Asker F hardness of the roller was 58 degrees, indicating that the roller had suitable characteristics. This conductive roller is incorporated in a dry electrophotographic apparatus as a toner supply roller, and the low temperature and low humidity conditions (15
After standing for 48 hours under high-temperature and high-humidity conditions (32.5 ° C., 85%), a solid white image and a solid black image were printed, and good images were obtained.

Comparative Example 1 Glycerin was added with 15% by weight of ethylene oxide and 85% by weight of propylene oxide.
After weighing 100 parts by weight of polyether polyol 800 and 22.2 parts by weight of tolylene diisocyanate (TDI-80) in a sealable container, closing the container lid, shaking the container and thoroughly mixing the contents. And placed in a hot air circulation oven at 60 ° C. Occasionally, the container was removed from the oven, shaken, and heated for 48 hours while mixing the contents. The NCO content of the prepolymer synthesized in this way was 6.1% by weight. Next, this prepolymer 10
Water-dispersed carbon containing conductive carbon with respect to 0 parts by weight [Lion paste W311 manufactured by Lion Corporation]
N, carbon content: 8% by weight] To 27 parts by weight, a 33% by weight dipropylene glycol solution of triethylenediamine as a catalyst [Kaolyser No. 3
1) A mixture in which 2.5 parts by weight of a reactive silicone foam stabilizer containing 0.6 parts by weight and 50% by weight of an ether chain is made of polyoxyethylene (30.1 parts by weight in total) was mixed by a high-speed mixer. , The mixture is 300 mm × 300 mm × 70
mm into a free foaming box without lid, and after foaming, 100 ℃
For 15 minutes to produce a conductive polyurethane foam. This foam was processed in the same manner as in Example 1 to produce a polyurethane foam conductive roller having an outer diameter of 13.4 mm and a length of 217 mm (polyurethane foam portion). The density of the polyurethane foam portion of this conductive roller is 0.089 g / cm ³ , and the number of cells is 81/25 m
m, residual compression set is 7.7%, tensile strength is 0.168MP
a, the roller resistance at 20 ° C. and 50% RH is ^105.20 Ω,
The Asker F hardness of the roller was 56 degrees, the compression set was small and good, but the cells were large. This conductive roller is incorporated in a dry electrophotographic apparatus as a toner supply roller, and the toner is supplied under low temperature and low humidity conditions (15 ° C., 10%) and high temperature and high humidity conditions (32.5 ° C., 85%), respectively.
After standing for a period of time, when a solid white image and a solid black image were printed, image unevenness considered to be caused by the coarse cells occurred under any of the conditions.

Comparative Example 2 Glycerin was added with 75% by weight of ethylene oxide and 25% by weight of propylene oxide.
100 parts by weight of a hydrophilic polyether polyol of 400 and tolylene diisocyanate (TDI-80) 23
Weigh the weight in a sealable container, close the lid of the container,
After shaking the container to thoroughly mix the contents, the container was placed in a 60 ° C. hot air circulation oven. Occasionally, the container was removed from the oven, shaken, and heated for 48 hours while mixing the contents. The NCO content of the prepolymer synthesized in this way was 5.9% by weight. Next, this prepolymer 1
Water-dispersed carbon containing conductive carbon with respect to 00 parts by weight [Lion paste W311 manufactured by Lion Corporation]
N, carbon content 8% by weight] 27 parts by weight of a 70% by weight solution of bis- (dimethylaminoethyl) -ether in dipropylene glycol as a catalyst [Kaolyzer No. 12] 0.1 part by weight, 70 of ether chain
A mixture in which 2.5 parts by weight of a reactive silicone foam stabilizer containing 2.5% by weight of polyoxyethylene was dissolved (total 29.6 parts by weight) was mixed by a high-speed mixer, and the mixture was mixed to a size of 300 mm.
The mixture was poured into a free foaming box having a size of 150 mm x 50 mm without a lid, foamed, and cured at 100 ° C for 15 minutes to produce a conductive polyurethane foam. This foam had strong closed cells and shrank and deformed as it cooled. I tried crushing the foam to prevent this shrinkage,
Crushing cannot be performed because the closed cells are strong,
When the foam was further compressed, the foam punctured, and a normal polyurethane foam usable for a roller could not be obtained.

Comparative Example 3 Glycerin was added with 75% by weight of ethylene oxide and 25% by weight of propylene oxide.
60 parts by weight of a hydrophilic polyether polyol of 400, 40 parts by weight of a polyether polyol having a weight average molecular weight of 4800 obtained by adding 15% by weight of ethylene oxide and 85% by weight of propylene oxide to glycerin, and tolylene diisocyanate (TDI-80) 21 parts by weight were weighed into a sealable container, the container was closed, the container was shaken to sufficiently mix the contents, and then placed in a 60 ° C. hot air circulation oven. Occasionally, the container was removed from the oven, shaken, and heated for 48 hours while mixing the contents. The NCO content of the prepolymer synthesized in this way was 6.0% by weight. Next, this prepolymer 10
Water-dispersed carbon containing conductive carbon with respect to 0 parts by weight [Lion paste W311 manufactured by Lion Corporation]
N, carbon content 8% by weight] 27 parts by weight of a 70% by weight solution of bis- (dimethylaminoethyl) -ether in dipropylene glycol as a catalyst [Kaolyzer No. 12] 0.1 part by weight, 70 of ether chain
A mixture in which 2.5 parts by weight of a reactive silicone foam stabilizer containing 2.5% by weight of polyoxyethylene was dissolved (total 29.6 parts by weight) was mixed by a high-speed mixer, and the mixture was mixed to a size of 300 mm.
The mixture was poured into a free foaming box having a size of 150 mm x 50 mm without a lid, foamed, and cured at 100 ° C for 15 minutes to produce a conductive polyurethane foam. This foam had strong closed cells and shrank and deformed as it cooled. I tried crushing the foam to prevent this shrinkage,
Crushing cannot be performed because the closed cells are strong,
When the foam was further compressed, the foam punctured, and a normal polyurethane foam usable for a roller could not be obtained.

Comparative Example 4 Glycerin was added with 15% by weight of ethylene oxide and 85% by weight of propylene oxide.
Solid content based on polyether polyol of 000 (acrylonitrile, styrene polymer)
About 28% by weight of a polymer polyol 60 parts by weight, glycerin added with 15% by weight of ethylene oxide and 85% by weight of propylene oxide, and has a weight average molecular weight of 4800.
Weighing 40 parts by weight of polyether polyol and 19 parts by weight of tolylene diisocyanate (TDI-80) in a sealable container, closing the lid of the container, shaking the container and thoroughly mixing the contents, and then heating at 60 ° C. In a hot air circulation oven. Occasionally, the container was removed from the oven, shaken, and heated for 48 hours while mixing the contents. The NCO content of the prepolymer synthesized in this way was 6.1% by weight. Next, bis- (dimethyl) as a catalyst was added to 27 parts by weight of water-dispersed carbon containing conductive carbon [Lion paste W311N, manufactured by Lion Corporation, carbon content 8% by weight] based on 100 parts by weight of the prepolymer. Aminoethyl) -ether in a 70% by weight dipropylene glycol solution [Kaolyser N, manufactured by Kao Corporation]
o. 12] A mixture of 0.1 part by weight and 2.5 parts by weight of a reactive silicone foam stabilizer comprising polyoxyethylene containing 70% by weight of an ether chain (total 29.6 parts by weight) was mixed with a high-speed mixer. , The mixture is 300 mm x 150 mm
Pour into a free foaming box without lid of × 50mm, and after foaming 1
This was cured at 00 ° C. for 15 minutes to produce a conductive polyurethane foam. This foam was processed in the same manner as in Example 1 to produce a polyurethane foam conductive roller having an outer diameter of 13.4 mm and a length of 217 mm (polyurethane foam portion). The density of the polyurethane foam portion of this conductive roller was 0.122 g / cm ³ , and the number of cells was 58 /
25 mm, compressive residual strain 6.6%, tensile strength 0.159
Roller resistance at 10MPa, 20 ° C, 50% RH is 10 ^5.40
Ω, Asker F hardness of the roller was 87 degrees, and the cells were larger and harder than the target polyurethane foam. This conductive roller is incorporated in a dry electrophotographic apparatus as a toner supply roller, and the low temperature and low humidity condition (1.
5 ° C, 10%) and high temperature and high humidity conditions (32.5 ° C, 85%)
After each of the samples was left for 48 hours, when a solid white image and a solid black image were printed, image irregularities considered to be caused by coarse cells occurred under any of the conditions.

[0022]

The conductive elastic member of the present invention has excellent characteristics such as low electric resistance, low hardness, fine cells, low residual compression strain, and high strength. The polyurethane foam forming the conductive elastic member is It can be manufactured by free foaming.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/16 103 G03G 15/16 103 5G301 H01B 1/24 H01B 1/24 Z // (C08G 18/48 (C08G 18/48 101: 00) 101: 00) F term (reference) 2H032 AA05 2H077 AC04 AD06 FA13 FA23 FA27 3J103 AA02 BA31 BA41 FA02 FA03 FA06 FA12 FA18 GA02 GA73 GA74 HA03 HA12 HA18 HA20 HA48 HA52 4J002 CK041 DA036 FD116 GQ4 BA07 DA01 DB04 DB05 DB07 DG03 DG04 DG08 DG09 DQ05 HA01 HA02 HA07 HC03 HC12 HC17 HC22 HC35 HC46 HC52 HC61 HC64 HC67 HC71 HC73 JA42 KA01 MA02 NA03 NA05 QA03 QA07 QB07 QB14 QB15 QB19 QC01 RA14 5G301 DA10 DD

Claims (10)

[Claims] 1. A conductive elastic member made of a polyurethane foam obtained by stirring and mixing a urethane prepolymer synthesized from a polyol and a polyisocyanate and water-dispersed carbon, wherein (A) an oxypropylene unit is 70% by weight as a polyol. % Or more of a polymer polyol synthesized on the basis of a polyether polyol containing at least 50% by weight of (B) an oxyethylene unit or 70% by weight or more of (A) an oxypropylene unit. 50% by weight of a polymer polyol synthesized based on a polyether polyol contained therein and (B) oxyethylene units
A conductive elastic member comprising a combination of the above-mentioned hydrophilic polyether polyol and a polyether polyol containing 70% by weight or more of (C) an oxypropylene unit. 2. The polyether polyol (C) wherein the oxypropylene unit in the polymer polyol (A) is 75 to 100% by weight, and the oxyethylene unit in the hydrophilic polyether polyol (B) is 60 to 100% by weight. The oxypropylene unit in is 75 to 10
The conductive elastic member according to claim 1, which is 0% by weight. 3. The mixing ratio of the polymer polyol (A), the hydrophilic polyether polyol (B) and the polyether polyol (C) is from 3 to 3 of the polymer polyol (A).
80% by weight, hydrophilic polyether polyol (B) 20
-60% by weight and polyether polyol (C) 0-6
The conductive elastic member according to claim 1, which is 0% by weight. 4. The conductive elastic member according to claim 1, wherein the water-dispersed carbon contains 5 to 20% by weight of carbon black. 5. The chemical equivalent ratio of NCO groups / OH groups of water contained in urethane prepolymer and water-dispersed carbon is 2
The conductive elastic member according to any one of claims 1 to 4, wherein the ratio is / 100 to 10/100. 6. The conductive elastic member according to claim 1, wherein the stirring and mixing of the urethane prepolymer and the water-dispersed carbon are performed by further adding a catalyst and a foam stabilizer. 7. The conductive elastic member according to claim 6, wherein the foam stabilizer is a polyether-modified silicone foam stabilizer, and the polyether portion of the foam stabilizer contains 60% by weight or more of oxyethylene units. . 8. The conductive elastic member has a roller shape, and the electric resistance of the roller is a logarithmic value [log].
Ω] is 3.0 to 6.0, Asker F hardness is 40 to 85 degrees, and the number of cells per 25 mm of polyurethane foam is 50 to
200 pieces, compression set is 1-10%, tensile strength is 0.1
The conductive elastic member according to any one of claims 1 to 7, which has a pressure of 5 to 0.5 MPa. 9. The conductive elastic member according to claim 1, wherein the conductive elastic member is a developer supply roller or a transfer roller for an image forming apparatus. 10. An image forming apparatus comprising the conductive elastic member according to claim 1.