JP2002132070A - Transfer roller and transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer roller having low hardness and wide nip width, and free of image fluctuation (lowering of image density, dispersion of gray level, void or the like), without soiling a photoreceptor or the like. SOLUTION: In the transfer roller, at least two or more elastic layers are formed on the outer periphery of a shaft, the elastic layer is provided with a non-foaming layer on the outside, at least one or more foaming layers are laminated on the inside of the non-foaming layer, and then a coating film, consisting mainly of synthetic resin components is formed on the surface of the non-coating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer roller suitably used for a transfer device such as an electrophotographic device such as a copying machine or a laser printer or an electrostatic recording device, and a transfer device using the same.

[0002]

2. Description of the Related Art Conventionally, in electrophotographic devices such as copiers and laser printers and electrostatic recording devices, paper, OHP,
A transfer roller that charges a recording medium such as a belt and transfers a developer to the recording medium or the like is used. First, in a color copying machine or the like, an image forming method in which a charged insulative toner image carried on an image carrier is primarily transferred to an intermediate transfer body and then secondary-transferred from the intermediate transfer body to a recording medium , A transfer roller for secondary transfer for charging a recording medium and transferring a toner image on an intermediate transfer member to the recording medium is used.

In a laser printer, an image forming method in which a charged insulating toner image carried on an image carrier is transferred onto a recording medium, the recording medium is charged and an electrostatic latent image visualized by the toner is charged. A transfer roller for transferring toner from an image to a recording medium is used.

In an image forming apparatus such as a laser printer, for example, as shown in FIG. 2, a photosensitive drum 1 is uniformly charged by a charger 2. Next, the exposure unit 3
Forms an electrostatic latent image, and is visualized by the developing device 4 to become a toner image. The toner image on the photoconductor is transferred to the transfer roller 5
When the toner image reaches the contact area with the toner image, the toner image is pressed against the recording paper 10 conveyed in synchronism with the toner image, and at the same time, a voltage is applied to the transfer roller 5 from the bias power supply 8. Is transferred to Reference numeral 6 denotes a bearing, reference numeral 7 denotes a spring, and reference numeral 9 denotes a cleaner.

Conventionally, as shown in FIG. 1, a transfer roller used in this image forming apparatus includes silicone rubber, NB on the outer periphery of a shaft 11 made of a good conductive material such as metal.
It has a structure in which a conductive material is blended with a main material such as an elastic rubber such as R or EPDM or urethane foam to form an elastic layer 12 provided with conductivity. Here, the hardness of the elastic layer 12 is used to obtain a uniform nip between the transfer roller and the photosensitive drum or an intermediate transfer member (hereinafter referred to as a “photosensitive drum or the like”), and to obtain an appropriate transfer amount with an increase in the speed of the apparatus. Therefore, it was necessary to have low hardness.

[0006]

However, the conventional transfer roller, particularly when the elastic layer is made of elastic rubber, has the following disadvantages. 1. In the step of charging the recording medium and transferring the developer to the recording medium or the like, the nip width between the transfer roller and the photosensitive drum or the like is reduced due to the high hardness of the elastic layer. As a result, since the recording medium passes through the transfer portion before the transfer electric field reaches a sufficient intensity when the voltage is applied, the transfer rate is reduced, and the transfer image quality on the recording paper is significantly reduced. is there.

2. When the nip width between the transfer roller and the photosensitive drum becomes small, pressure concentrates on the central part of the character or image, so that toner particles cannot be transferred from the surface of the photosensitive drum to the recording paper. , The so-called "empty" or "
There are problems such as "white spots".

[0008] 3. Further, as a method of lowering the hardness of the elastic layer, a method of adding various plasticizers to the main material of the elastic layer has been attempted, but the bleeding of the plasticizer contaminates the surface of the photosensitive drum or the like. There is a problem.

When the elastic layer is made of urethane foam, there are the following disadvantages. 1. If the cell diameter of urethane foam is not uniform,
There is also a problem that the roller resistance becomes non-uniform and that the density of the transferred image varies.

[0010] 2. Further, there is a problem that the toner adhered to the surface of the transfer roller moves to the back surface of the recording paper, thereby causing the back contamination of the recording paper. In order to avoid this problem, a method of cleaning the surface of the transfer roller, for example, a method of applying a bias having the same polarity as the toner to the transfer roller, or a method of contacting the transfer roller with a blade or a roller to remove the toner. Although there is a scraping method, the cleaning with a blade or a roller has a problem that the attached toner enters the cell portion of the foam and cannot be cleaned.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, has a low hardness and a wide nip width, does not cause inconvenience such as contaminating a photoreceptor, etc., and reduces the image density or the image quality. There is little shading variation and "
It is an object of the present invention to provide a transfer roller and a transfer device using the transfer roller, which hardly generate “hollow spots” or “white spots” and do not cause back stains on recording paper.

[0012]

A transfer roller according to the present invention comprises:
At least two or more elastic layers are formed on the outer periphery of the shaft. The transfer roller charges the recording medium and transfers the developer to the recording medium. At least one or more foam layers are laminated on the inner side of the non-foam layer, a coating mainly composed of a synthetic resin component is provided on the surface of the non-foam layer, and the transfer roller has an Asker C hardness of 10 to 70. °, the surface roughness is not more than 50 μm on a JIS 10-point average roughness Rz scale.

The transfer roller of the present invention has an Asker C hardness of 45 ° or less of the foam layer, a compression set of 10% or less according to JIS-K6401, a temperature of 22 ° C. and a humidity of 5%.
In a 5% environment, a volume resistivity value when a voltage of 50 V is applied is 1 × 10 ² Ωcm to 1 × 10 ⁸ Ωcm.

In the transfer roller of the present invention, the non-foamed layer has an Asker C hardness of 40 to 85 °, a temperature of 22 ° C., a humidity of 55%, and a volume specific resistance of 1 × 10 ³ when a voltage of 50 V is applied. ^１1 × 10 ¹¹ Ωcm.

The transfer device according to the present invention comprises a transfer roller for charging a recording medium and transferring a developer to the recording medium. A transfer roller according to any one of the preceding claims is used.

[0016]

DETAILED DESCRIPTION OF THE INVENTION That is, the present inventors have made intensive studies on the above-mentioned problems, and as a result, formed a transfer roller of the present invention by forming at least two elastic layers on the outer periphery of a shaft and charging a recording medium. A transfer roller for transferring a developer to a recording medium, wherein the elastic layer is provided with a non-foamed layer on the outside, and at least one or more foamed layers are laminated inside the non-foamed layer; The surface is provided with a coating mainly composed of a synthetic resin component, and the transfer roller has an Asker C hardness of 10 to 70 ° and a surface roughness of 50 μm or less on a JIS 10-point average roughness Rz scale. The inventors have found that the problems can be solved, and have completed the present invention.

Although the detailed mechanism is not clear, a non-foamed layer and at least one or more foamed layers are laminated on the inner side of the non-foamed layer, and the non-foamed layer has a specific range of hydroxyl value. Since it is composed of a urethane elastomer comprising a hydrophobic and hydrophilic polyol and a diphenylmethane diisocyanate-based isocyanate, the hardness of the entire transfer roller can be 10 to 70 in Asker C hardness without causing inconvenience such as contamination of the photoreceptor. °, so that the nip width between the transfer roller and the photosensitive drum can be widened, the electric field strength between the transfer roller and the photosensitive drum can be secured in a sufficiently stable state, and a decrease in transfer efficiency can be prevented. In addition, since the nip width between the transfer roller and the photosensitive drum can be sufficiently secured, In addition, since the non-foamed layer is provided on the outer side, when the transfer roller surface is cleaned with a blade, the toner adhered to the transfer roller surface can be sufficiently scraped off by the blade, so that the back stain of the recording paper can be prevented. .

Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 3 is a schematic diagram illustrating an example of the transfer roller of the present invention. Here, a transfer roller in which a foam layer 12 is formed on the outer periphery of the shaft 11, a non-foam layer 13 is further formed on the outer periphery thereof, and a coating 14 mainly composed of a synthetic resin component is provided on the surface of the non-foam layer 13 Is shown.
The non-foamed layer has functions of blade cleaning and abrasion resistance, and the foamed layer has a function of low hardness. Also,
The elastic layer may be two or more layers, and the outside is a non-foamed layer,
Any combination may be used except that at least one layer on the inside is a foam layer. For example, the combination may be a non-foamed layer / foamed layer / foamed layer, a non-foamed layer / foamed layer /
Non-foamed layer, non-foamed layer / non-foamed layer / foamed layer, non-foamed layer / foamed layer / foamed layer / foamed layer, non-foamed layer / foamed layer / non-foamed layer /
Foam layer / foam layer. The roller hardness of the present invention is 10 to 70 ° in Asker C hardness, preferably,
20 to 50 °.

The shaft 11 according to the present invention is not particularly limited. For example, the material is a metal or a resin. In the case of a resin shaft, conductivity may be imparted according to the purpose.

The material suitable for the foam layer 12 is not particularly limited. For example, thermoplastic foams such as polyethylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, viscose, and ionomer, or urethane, rubber foam, epoxy, phenol urea, Pyranyl, silicone, thermosetting foams such as acrylic, and the like,
Urethane is the best among them.

When the material of the foam layer 12 is urethane, any hydrophobic or hydrophilic polyol can be used as the polyol. Among them, polypropylene glycol and a polyether-based polyol of an ethylene oxide adduct are preferred from the viewpoint of economy and handleability. The isocyanate is not particularly limited, but tolylene diisocyanate is preferred from the viewpoint of economy and handleability.

The foam layer 12 has a hardness of 45 ° or less in Asker C hardness, a volume resistivity of 22 ° C.
1 × 10 ² -1 when a voltage of 50 V is applied in an environment of 55% humidity
× 10 ⁸ Ωcm, density 0.005 to 0.5 g / c
m ³ , preferably 0.05 to 0.5 g / cm ³ , and a compression set of 10% or less (based on JIS-K-6401), particularly 5% or less, and if it exceeds 10%, the nip width may vary or The pressure applied to the intermediate transfer member or the photoreceptor fluctuates, which may cause significant image degradation. Further, as the cell form of the foamed layer 12, any form such as a closed cell and an open cell can be used, but the open cell is preferable because the dimensional change due to temperature is small.

The method for producing the foamed layer 12 is not particularly limited. Particularly in the case of urethane foam, for example, in the case of a one-shot method, a polyol, tolylene diisocyanate, a conductive material for imparting conductivity, The catalyst, surfactant, water, and other additives are simultaneously mixed and stirred, and the foamed reaction mixture is poured into a mold in which a metal shaft is set in advance, and cured at 50 to 90 ° C. for several hours. The obtained molded body is polished and finished into a roller, but may be left as it is when a cylindrical mold is used. In the prepolymer method, a prepolymer is once prepared from a polyol and tolylene diisocyanate, and then the obtained prepolymer, the same or different polyol as used in the preparation of the prepolymer, a conductive material for imparting conductivity, and a catalyst are used. , A surfactant, water, and other additives are simultaneously mixed and stirred, and a roller is manufactured from the foamed reaction mixture by a method similar to the one-shot method. Further, when another layer is formed on the foam layer 12, the outer skin of the foam layer, that is, the skin layer may be removed by polishing, or another layer may be formed without polishing. Note that an adhesive layer may be provided between the metal shaft and the foam layer.

The material suitable for the non-foamed layer 13 is not particularly limited, and examples thereof include urethane elastomers comprising a hydrophobic and / or hydrophilic polyol and a diphenylmethane diisocyanate-based isocyanate.

Examples of hydrophobic polyols include polyisoprene polyols, polybutadiene polyols or their styrene, acrylonitrile copolymers and their hydrogenated polyolefin polyols or silicone polyols, fluorine polyols, castor oil-based polyols, etc. Dimer acid polyols or mixtures thereof are used. In addition, polytetramethylene ether glycol may be mixed with these hydrophobic polyols for the purpose of lowering the viscosity without increasing the physical properties and improving the castability. Examples of the polytetramethylene ether glycol include those obtained by grafting a substituent such as an alkyl group such as a methyl group to the methylene group in addition to ordinary polytetramethylene ether glycol, or an alkylene oxide such as propylene oxide on the main chain. Can also be used. The hydroxyl value is 15 to 120.
mgKOH / g is preferable, and if it is less than 15 mg, the viscosity of the polyol becomes too high, and if it exceeds 120 mg, the obtained urethane elastomer becomes hard, which is not preferable. Further, the number of functional groups of the polyol is preferably 1.5 to 3.0, and if it is less than 1.5, the tackiness of the obtained urethane elastomer becomes large, and if it exceeds 3.0, the obtained urethane elastomer becomes hard, which is not preferable. .

Next, examples of the hydrophilic polyol include polyether polyols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, and aliphatic polyols such as ethylene glycol, propylene glycol, butylene glycol, pentene glycol and hexene glycol. Glycols such as polyalkylene glycols such as glycol, diethylene glycol and dipropylene glycol, and tri- or higher functional polyhydric alcohols such as trimethylolpropane are used as components, and these are adipic acid, sebacic acid, suberic acid, and brassic acid. Polyethers such as condensed polyester polyols obtained from polybasic acid components such as aliphatic dicarboxylic acids such as succinic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; Ether polyols, or a mixture thereof is being given. The hydroxyl value is 5 to 130.
mgKOH / g is preferable, and if it is less than 5 mg, the viscosity of the polyol becomes too high, and if it exceeds 130 mg, the obtained urethane elastomer becomes hard, which is not preferable. Further, the number of functional groups of the polyol is preferably 2 to 6,
If it is less than 2, the tackiness of the obtained urethane elastomer increases, and if it exceeds 6, the obtained urethane elastomer becomes hard, which is not preferable.

The properties of the non-foamed layer 13 are not particularly limited, but its hardness is 40 to 85 ° in Asker C hardness, and the volume specific resistance of the non-foamed layer is 22 ° C., 55% humidity, 1 × 10 ³ to 1 × 10 ¹¹ Ωcm when 50 V is applied
Is preferred. The thickness of the non-foamed layer is not particularly limited, but is preferably 0.1 to 2.0 mm, and 0.1 mm
If it is less than 1, the durability when contact with other members and wear is advanced is insufficient, and if it exceeds 2.0 mm, the hardness of the entire roller becomes too high, and sufficient flexibility cannot be obtained. . Further, the roller surface roughness is JIS 10 point average roughness R
It is 50 μm or less, more preferably 20 μm or less, further preferably 10 μm or less on the z-scale.

As the isocyanate for the non-foamed layer 13, a diphenylmethane diisocyanate-based isocyanate is used. For example, crude diphenylmethane-4,4 'diisocyanate (crude MDI or polymeric MD
I), carbodiimide-modified diphenylmethane-4,4 ′ diisocyanate, uretonimine-modified diphenylmethane-4,4 ′ diisocyanate, and other liquid diphenylmethane-4,4 ′ diisocyanate, urethane-modified diphenylmethane-4,4 ′ diisocyanate, diphenylmethane-4, 4 'diisocyanate, diphenylmethane-2,2' diisocyanate or a mixture thereof is preferably used. The number of functional groups of the isocyanate is 2 to 5, preferably 2 to 3.5. If the number is less than 2, the obtained polyurethane elastomer may contaminate the contacted substance, and becomes brittle if it exceeds 3.5.

The mixing ratio of the polyol and the isocyanate is suitably adjusted so that the ratio of the isocyanate group to the hydroxyl group in the polyol is 0.7 to 2.0, preferably 0.9 to 1.3. If it is less than this range, the resulting polyurethane elastomer may contaminate the contacted material, and it becomes undesirably brittle above this range.

The method for producing the non-foamed layer 13 is not particularly limited. Particularly in the case of urethane foam, for example, in the case of a one-shot method, a polyol, isocyanate, a conductive material for imparting conductivity, a catalyst, Then, the other additives are mixed and stirred at the same time, and a foam to be a foamed layer is poured into a mold in which a metal shaft having a roller shape formed on the outer periphery is set in advance, and cured at 50 to 90 ° C. for several hours. The obtained molded body is polished and finished into a roller. Alternatively, when a cylindrical mold is used, the mold may be left as it is. In the prepolymer method, a prepolymer is once prepared from a polyol and a bifunctional isocyanate, for example, diphenylmethane-4,4 'diisocyanate, and then the obtained prepolymer, the same or a different polyol as used in the preparation of the prepolymer, and a conductive polymer. A conductive material for imparting properties, a catalyst, and other additives are simultaneously mixed and stirred, and thereafter, a roller is manufactured by a method similar to the one-shot method. The non-foamed layer may be polished after the roller is manufactured.

Examples of the conductive material for imparting conductivity to the foamed layer 12 or the non-foamed layer 13 include powdered conductive carbon such as Ketjen Black EC and acetylene black, SAF, ISAF, and the like. HAF, FE
Rubber carbon such as F, GPF, SRF, FT, MT, etc.
Metals and metal oxides such as color (ink) carbon, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium, etc.
Examples thereof include conductive polymers such as polyaniline, polypyrrole, and polyacetylene. Among them, carbon black is inexpensive and easily controls conductivity in a small amount. Usually, the amount of these conductive materials is 0.5 to 50 parts by weight, especially 1 to 3 parts by weight, per 100 parts by weight of urethane.
It is suitably used in the range of 0 parts by weight.

Examples of ion conductive substances include sodium perchlorate, lithium perchlorate, calcium perchlorate,
Inorganic ionic conductive materials such as lithium chloride, further tridecylmethyldihydroxyethylammonium perchlorate, lauryltrimethylammonium perchlorate,
Modified aliphatic dimethylethylammonium ethosulfate, N, N-bis (2-hydroxyethyl) -N-
(3'-dodecyloxy-2'-hydroxypropyl) methylammonium ethosulfate, 3-lauramidopropyl-toemethylammonium methylsulfate, stearylamidopropyldimethyl-β-hydroxyethyl-ammonium-dihydrogenphosphate, tetrabutyl Quaternary ammonium perchlorates, sulfates, such as ammonium borate, stearyl ammonium acetate, lauryl ammonium acetate,
Examples thereof include organic ionic conductive substances such as ethosulfate salt, methylsulfate salt, phosphate, borofluoride, and acetate, or charge transfer complexes. Usually, the amount of these conductive materials is suitably used in the range of 0.0001 to 50 parts by weight based on 100 parts by weight of urethane.

The urethane elastomer of the non-foamed layer 13 contains various charge control agents such as nigrosine, triaminophenylmethane, cationic dyes, and fine powders such as silicone resin, silicone rubber, and nylon for the purpose of controlling transfer efficiency. Can be added. In this case, the addition amount of these additives is preferably 1 to 5 parts by weight, and the fine powder is preferably 1 to 10 parts by weight, based on 100 parts by weight of the polyurethane.

On the surface of the non-foamed layer 13, a film mainly composed of a synthetic resin component is formed for the purpose of improving the durability of the roller or controlling the transfer efficiency. The synthetic resin component is not particularly limited. For example, a soluble nylon resin such as “CM-833” and “CM8000” manufactured by Toray Industries, Inc., a solution obtained by dissolving a fluororesin in a solvent, water, or the like, or a fluororesin is used. Water-based latex, for example, "Luflon 1000" and "Velflon 1300" manufactured by NOF Corporation, "Lumiflon LT-" manufactured by Asahi Glass Co., Ltd.
FE-3000, "Lumiflon 600", "Lumiflon 8"
00 ”and the like,“ Zeffle LC9 ”manufactured by Daikin Industries, Ltd.
30) "Daier Latex GLS-213" and "G
LS-213D "," Polyflon TFE tough coat enamel TC-7400 "and the like, or a mixture of two or more resins selected from fluororesins, acrylic resins, urethane-modified acrylic resins, polycarbonate resins, silicone resins and melamine resins. . Further, the above-mentioned conductive material may be added to the synthetic resin component. In addition, a dip coating method, a trans coating method, an in-mold coating method, a roller coating method, and the like are suitable as a film forming method.

In the present invention, the volume specific resistance value of the transfer roller is not particularly limited.
1 × 10 ³ at a voltage of 50 V under an environment of 55 ° C. and 55% humidity
~ 1 × 10 ¹⁰ Ωcm, especially 1 × 10 ⁴ -1 × 10 ⁹ Ωc
m is preferable. If the resistance value is less than 1 × 10 ³ Ωcm, the charge may leak to the intermediate transfer member or the photosensitive drum, or the transfer roller itself may be broken by the voltage, while if it exceeds 1 × 10 ¹⁰ Ωcm. Therefore, an appropriate discharge cannot be obtained between the transfer roller and the intermediate transfer member or the photosensitive drum.

Since the transfer roller obtained by the present invention has a very good shape followability and a low hardness, a sufficient followability can be obtained even when the contact nip with respect to a contact object such as a photoreceptor is increased. By increasing the nip width at a low contact pressure, it is possible to improve the image quality and increase the transfer speed. When the nip width is set to 3 mm or more, more preferably 5 mm or more with respect to the photoreceptor or the like, the performance of the transfer roller of the present invention can be sufficiently brought out.

[0037]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following. [Example 1] Prepolymer 1 obtained by reacting tolylene diisocyanate with a polyether polyol having 3 functional groups and a molecular weight of 5,000 so that the NCO% becomes 6.7.
To 00 parts by weight (hereinafter simply referred to as "parts"), 6.46 parts of 1,4-butanediol, 2 parts of a silicone surfactant, 0.003 parts of dibutyltin dilaurate and 2.2 parts of acetylene black were added and mixed. After stirring for 2 minutes using a mixer, a shaft having an outer diameter of 8 mm was set in advance, and the reaction mixture was poured into a mold preheated to 60 ° C.
Time cured. After removal from the mold, polishing was performed to obtain a urethane foam roller having an outer diameter of 15 mm. According to the following method, a roller having a hydrophobic urethane elastomer as the outermost layer and a two-layer structure having a urethane foam inside and having an outer diameter of 16 mm was obtained on the thus obtained urethane foam roller.

First, the hydroxyl value was 47.1 and the number of functional groups was 2.4.
3.1 parts of acetylene black was added to 100 parts of the polyisoprene polyol, and the mixture was degassed under reduced pressure while stirring under vacuum for 30 minutes. Then, 12.7 parts of crude diphenylmethane-4,4 ′ diisocyanate having an NCO% of 31.7 and After adding 0.001 part of dibutyltin dilaurate and stirring for 3 minutes while also defoaming under reduced pressure, a urethane foam roller manufactured in advance as described above is set, and the reaction mixture is poured into a mold preheated to 60 ° C. Then, curing was performed at 90 ° C. for 16 hours, and after demolding, polishing was performed so that the outer diameter became 16 mm. The surface of the finished roller has no tackiness,
Asker C hardness was 37 ° and resistance was 1 × 10 ⁸ Ω.

The obtained roller was immersed for 10 seconds in a solution in which 5% by weight of a fluororesin soluble in toluene was dissolved.
The roller was pulled out and dried to perform a surface treatment. To test the contamination of the roller to the photosensitive drum, the roller was pressed against the photosensitive drum of a printer PC-PR1000E / 4 manufactured by NEC with a load of 500 g at both ends, and left at 55 ° C. and 85% humidity for 5 days. No trace was left on the surface of the photosensitive drum after the removal, and there was no effect even if the image was mounted on the printer and displayed.

FIG. 2 shows the characteristics of the transfer roller.
In the transfer unit shown in (1), images of gray scale, solid black, and solid white were formed and the stain on the back of the paper was observed. As a result, good image quality was obtained. When a character image was displayed, clear image quality without missing characters was obtained. Table 1 shows the above evaluation results together with the results of the other examples and comparative examples.

[0041]

[Table 1]

[Example 2] A roller having a two-layer structure in which a hydrophobic urethane elastomer obtained by the same method as in Example 1 was the outermost layer and the inside was urethane foam was used. A soluble copolymer nylon is dissolved in a solvent so as to have a concentration of 10%, and then carbon is added as a conductive agent at a speed of 1 cm / sec into a conductive paint mixed with 20 phr of the nylon, and the roller is pulled up at the same speed. After drying, the same measurement as in Example 1 was performed.

Comparative Example 1 3.1 parts of acetylene black was added to 100 parts of a polyisoprene polyol having a hydroxyl value of 47.1 and a functional group of 2.4, and the mixture was degassed under reduced pressure while stirring under vacuum for 30 minutes. % Of crude diphenylmethane-4,4 'diisocyanate (11.7 parts) and dibutyltin dilaurate (0.001 parts) were added, and the mixture was stirred for 3 minutes while defoaming under reduced pressure, and a shaft having an outer diameter of 8 mm was set in advance. Then, the reaction mixture was poured into a 17 mm inner diameter mold preheated to 90 ° C., cured at 90 ° C. for 16 hours, demolded, and polished to an outer diameter of 16 mm.
The same measurement as in Example 1 was performed.

Comparative Example 2 A polyether polyol having a hydroxyl value of 33.7 and a functional group number of 3.0 was used as a polyol component, and 9.2 parts was used as an isocyanate component, except that 9.2 parts were used. A roller was manufactured, and the same measurement as in Example 1 was performed.

Comparative Example 3 The number of functional groups was 3, and the molecular weight was 5000.
100 parts of a prepolymer obtained by reacting tolylene diisocyanate with NCO% of 6.7 to 1,4-butanediol 6.4
6 parts, 2 parts of a silicone surfactant, 0.003 parts of dibutyltin dilaurate and 2.2 parts of acetylene black are added, and the mixture is stirred for 2 minutes using a mixer.
The reaction mixture was poured into a mold preheated to 60 ° C., and cured at 60 ° C. for 12 hours.
After removal from the mold, polishing was performed to obtain a urethane foam roller having an outer diameter of 16 mm, and the same measurement as in Example 1 was performed.

[0046]

That is, in the roller of the present invention, at least one layer other than the outermost layer is a foam, and the outermost layer is a urethane comprising a hydrophobic and hydrophilic polyol having a hydroxyl value in a specific range and a diphenylmethane diisocyanate series isocyanate. The hardness of the roller as a whole can be reduced without causing any inconvenience such as contaminating the photoreceptor, etc. by providing a coating composed mainly of a synthetic resin component on the surface of this outermost layer. Since the C hardness can be changed from 10 ° to 70 °, the nip width between the transfer roller and the intermediate transfer member or the photosensitive drum can be widened, and a decrease in transfer efficiency can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a conventional transfer roller.

FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus such as a laser printer using the transfer roller of the present invention.

FIG. 3 is a schematic diagram illustrating an example of a transfer roller of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charger 3 Image exposure system 4 Developing device 5 Transfer roller 10 Recording paper 11 Shaft 12 Foaming layer (elastic layer) 13 Non-foaming layer 14 Coating

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshio Takizawa 1628-1-411, Kumakawa, Fussa-shi, Tokyo (72) Inventor Koji Takagi 3-21-33-304, Miyauchi-ku, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture (72) Inventor Takahiro Kawagoe 1302-57 Aobadai, Tokorozawa-shi, Saitama F-term (Reference) 2H200 FA08 GA23 HA04 HB03 JA02 JA23 JA25 JA26 JA27 JA28 JB10 MA02 MA08 MA17 MA20 MB04 MC02 MC03 MC06 NA02 3J103 AA02 AA15 AA32 AA51 BA41 EA02 GA04 FA05 HA12 HA20 HA41 HA42 HA43 HA45 HA46 HA48 HA53 HA54 4J034 DA01 DB03 DB07 DF01 DF16 DF20 DF21 DF22 DG03 DG04 DM02 DP03 DP12 DP15 DQ08 DQ09 EA12 GA03 GA05 GA06 HA01 HA07 HC06 HC12 HC33 HC64 HC67 HC71 QA02 RA11 RA

Claims (14)

[Claims] 1. A transfer roller having at least two elastic layers formed on the outer periphery of a shaft and charging a recording medium to transfer a developer to the recording medium, wherein the elastic layer has a non-foamed layer on the outside. At the same time, at least one or more foam layers are laminated inside the non-foam layer, and a coating mainly composed of a synthetic resin component is provided on the surface of the non-foam layer,
And the Asker C hardness of the transfer roller is 10 to 70.
°, surface roughness is 5 on JIS 10-point average roughness Rz scale
A transfer roller having a thickness of 0 μm or less. 2. The transfer roller according to claim 1, wherein the non-foamed layer is a urethane elastomer produced mainly by a one-shot method from a hydrophobic polyol and a diphenylmethane diisocyanate-based isocyanate. 3. The transfer roller according to claim 1, wherein the non-foamed layer is a urethane elastomer produced mainly by a polyol and a prepolymer mainly composed of a hydrophobic polyol and a diphenylmethane diisocyanate isocyanate. 4. The hydrophobic polyol having a hydroxyl value of 15
The transfer roller according to claim 2 or 3, wherein the transfer roller has a functional group number of 1.5 to 3 mgKOH / g. 5. The transfer roller according to claim 1, wherein the non-foamed layer is a urethane elastomer produced mainly by a one-shot method from a hydrophilic polyol and a diphenylmethane diisocyanate-based isocyanate. 6. The transfer roller according to claim 1, wherein the non-foamed layer is a urethane elastomer produced mainly by a polyol and a prepolymer composed of a hydrophilic polyol and a diphenylmethane diisocyanate-based isocyanate. 7. The hydrophilic polyol having a hydroxyl value of 5 to 5.
The transfer roller according to claim 5 or 6, wherein the transfer roller has a functional group number of 2 to 6 at 130 mgKOH / g. 8. The synthetic resin component according to claim 1, wherein a resin selected from a soluble nylon resin, an acrylic resin, a urethane-modified acrylic resin, a polycarbonate resin, a silicone resin, a fluororesin and a melamine resin is used alone or in combination of two or more. Any one of claims 1 to 7
The transfer roller according to the item. 9. The transfer roller according to claim 1, wherein a conductive substance is added to the synthetic resin component. 10. The non-foamed layer has a thickness of 0.1 to 2.0.
The transfer roller according to any one of claims 1 to 9, wherein 11. The above-mentioned foamed layer is a flexible foam selected from a foam made of polyethylene, polyvinyl chloride, polystyrene, rubber foam, polyvinyl alcohol, viscose, ionomer, urethane, epoxy, phenol, urea, pyranyl, silicone, and acrylic. The transfer roller according to any one of claims 1 to 10, wherein the transfer roller is provided. 12. The Asker C hardness of the foam layer is 45 °.
Hereinafter, the compression set according to JIS-K6401 is 10
% Or less, a temperature of 22 ° C. and a humidity of 55%, a volume resistivity value of 1 × 10 ² Ωcm to 1 × when a voltage of 50 V is applied.
12. The pressure of 10 ⁸ Ωcm.
The transfer roller according to any one of the above items. 13. The Asker C hardness of the non-foamed layer is 40.
~ 85 °, temperature 22 ° C, humidity 55%, voltage 50V
Volume resistivity value at the time of application is 1 × 10 ³ to 1 × 10
The transfer roller according to claim 1, wherein the transfer roller has a resistance of ¹¹ Ωcm. 14. A transfer device comprising a transfer roller for charging a recording medium and transferring a developer to the recording medium, wherein the transfer roller is used as the transfer roller.
A transfer device using the transfer roller according to any one of the above.