JPH09171309A - Transfer roller and transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to widen the nip width between a transfer roller and an intermediate transfer medium or a photoreceptor drum and to prevent the degradation in transfer efficiency by providing the outer side of the elastic layers of the transfer roller with a non-foamed layer and laminating at least >=1 layers of foamed layers on the inner side of this non-foamed layer, thereby providing a roller with a specific hardness and surface roughness. SOLUTION: This transfer roller has at least >=2 layers of the elastic layers formed on the outer periphery of a shaft and transfers developer to a recording medium by electrostatically charging this recording medium. The outer side of the elastic layer of such transfer roller is provided with the non-foamed layer 13 and at least >=1 layer of the foamed layers 12 are laminated on the inner side of the non-foamed layer 13. In addition, the Asker C hardness of the transfer roller is specified to 10 to 70 deg. and the surface roughness to <=50μm in 10 points average roughness Rz scale stipulated in JIS(Japanese Industrial Standards). The non-foamed layer 13 is composed of a urethane elastomer consisting of hydrophobic or hydrophilic polyol having a hydroxyl value in a specific range and isocyanate of a diphenylmethane diisocyanate series.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer roller suitable for use in 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 copying machines and laser printers and electrostatic recording devices, paper, OHP,
A transfer roller that charges a recording medium such as a belt and transfers the developer to the recording medium is used. First, in a color copying machine or the like, an image forming method in which a charged insulating toner image carried on an image carrier is first transferred to an intermediate transfer member and then secondarily transferred from the intermediate transfer member to a recording medium. In the above, a transfer roller for secondary transfer is used for charging the recording medium and transferring the toner image on the intermediate transfer body to the recording medium.

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

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

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

[0006]

However, there are the following drawbacks when the conventional transfer roller, especially when the elastic layer is made of elastic rubber. 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 becomes small 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 strength when a voltage is applied, the transfer rate is reduced, and the transfer image quality on the recording paper is significantly reduced. is there.

2. Further, when the nip width between the transfer roller and the photosensitive drum is reduced, the pressure is concentrated on the central portion of the character / image, so that the toner particles cannot be transferred from the surface of the photosensitive drum to the recording paper. , So-called "Cutout" 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 bleeding of the plasticizer contaminates the surface of the photosensitive drum or the like. I have a problem.

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

[0010] 2. Further, there is a problem that the toner adhering to the surface of the transfer roller is transferred to the back surface of the recording paper and the back surface of the recording paper is stained. 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 blade or roller is brought into contact with the transfer roller to remove the toner Although there is a scraping method, cleaning with a blade or a roller has a problem that the adhered toner enters the cell portion of the foam and cleaning is impossible.

The present invention has been made in view of the above circumstances, has a low hardness and a wide nip width, and does not cause the inconvenience of contaminating a photosensitive member or the like, and also reduces the image density or the image. There is little variation in light and shade, and "
An object of the present invention is to provide a transfer roller and a transfer device using the transfer roller, in which almost no "blank area" or "blank area" occurs and the backside of the recording paper does not occur.

[0012]

The transfer roller of the present invention comprises:
In a transfer roller having at least two elastic layers formed on the outer periphery of a shaft for charging a recording medium and transferring a developer to the recording medium, the elastic layer is provided with a non-foaming layer on the outside. At least one foam layer is laminated inside the non-foam layer, and the transfer roller has an Asker C hardness of 10 to 70 ° and a surface roughness of JIS.
The 10-point average roughness Rz scale is 50 μm or less.

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

Further, 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 resistivity value of 1 × 10 ³ when a voltage of 50 V is applied. It is characterized in that it is ˜1 × 10 ¹¹ Ωcm.

The transfer device of the present invention comprises a transfer roller for charging a recording medium and transferring a developer to the recording medium, wherein the transfer roller is the transfer roller according to any one of claims 1 to 14. The transfer roller according to any one of the items is used.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a result of intensive studies on the above problems, the present inventors have found that the transfer roller of the present invention has at least two elastic layers formed on the outer periphery of a shaft to charge a recording medium. A transfer roller for transferring a developer to a recording medium, wherein the elastic layer is provided, a non-foaming layer is provided outside, and at least one foaming layer is laminated inside the non-foaming layer; Has an Asker C hardness of 10 to 70 ° and a surface roughness of JIS 10 point average roughness Rz.
The inventors have found that the problem can be solved by setting the scale to 50 μm or less, 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 inside the non-foamed layer, and the non-foamed layer has a hydroxyl value in a specific range. Since it is composed of a urethane elastomer composed of a hydrophobic or hydrophilic polyol and an isocyanate of diphenylmethane diisocyanate series, the hardness of the entire transfer roller is 10 to 70 in terms of Asker C hardness without causing any inconvenience such as contaminating a photoreceptor or the like. Since the angle can be set to 0, the nip width between the transfer roller and the photosensitive drum etc. can be widened, the electric field strength between the transfer roller and the photosensitive drum etc. can be secured in a sufficiently stable state, and the decrease in transfer efficiency can be prevented. It is conceivable that it is possible to secure a sufficient nip width between the transfer roller and the photosensitive drum. Moreover, since a non-foaming layer is provided on the outside, when the transfer roller surface is cleaned with a blade, the toner adhering to the transfer roller surface can be sufficiently scraped off with the blade, so the backside of the recording paper can be prevented. .

The present invention will be described in more detail below with reference to the drawings. FIG. 3 is a schematic view showing an example of the transfer roller of the present invention. Here, a transfer roller in which a foamed layer 12 is formed on the outer circumference of the shaft 11 and a non-foamed layer 13 is formed on the outer circumference thereof is shown, and the non-foamed layer is provided with functions of blade cleaning and abrasion resistance. The foam layer has a low hardness function. Further, the elastic layer may be composed of two or more layers, in which the outer side is a non-foamed layer and the inner side is at least 1 layer.
Any combination may be used except that the layers are foam layers. For example, the combination is, from the outside, non-foamed layer / foamed layer / foamed layer, 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 / foamed layer / foamed layer and the like. The roller hardness of the present invention is Asker C
The hardness is 10 to 70 °, preferably 20 to 50 °.

The shaft 11 according to the present invention is not particularly limited, and examples thereof include metal and resin. However, in the case of a resin shaft, conductivity may be imparted depending on the purpose.

The material suitable for the foam layer 12 is not particularly limited, but examples thereof include thermoplastic foams such as polyethylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, viscose, and ionomer, or urethane, rubber foam, epoxy, phenol urea, Examples include thermosetting foams such as pyranyl, silicone, and acrylic.
Among them, urethane is the most suitable.

When the material of the foam layer 12 is urethane, any polyol having hydrophobicity or hydrophilicity can be used as the polyol. Among these, from the viewpoints of economy and handleability, polypropylene glycol and a polyether-based polyol of an ethylene oxide adduct are preferable. The isocyanate is not particularly limited, but tolylene diisocyanate is preferable from the viewpoints of economy and handleability.

The characteristics of the foam layer 12 are that the hardness is 45 ° or less in Asker C hardness, the volume specific resistance is 22 ° C.,
1 × 10 ² to 1 when a voltage of 50 V is applied in a 55% humidity environment
× 10 ⁸ Ωcm, density 0.005-0.5 g / cm
³ , preferably 0.05 to 0.5 g / cm ³ , a compression set of 10% or less (JIS-K-6401 standard), especially 5
% Or less is preferable, and if it exceeds 10%, the nip width may fluctuate or the pressure applied to the intermediate transfer member or the photosensitive member may fluctuate, which may cause remarkable image deterioration. Further, the cell form of the foam layer 12 may be any form such as a single bubble or an open cell, but the open cell is preferable because the dimensional change due to temperature is less.

The method for producing the foamed layer 12 is not particularly limited, but particularly in the case of urethane foam, for example, in the case of the one-shot method, polyol, tolylene diisocyanate, a conductive material for imparting conductivity, A catalyst, a surfactant, water, and other additives are mixed and stirred at the same time, 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 ground to be a roller, but when a cylindrical mold is used, it may be released from the mold. Further, 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 when the prepolymer is prepared, a conductive material for imparting conductivity, a catalyst , A surfactant, water, and other additives are mixed and stirred at the same time, and a roller is manufactured from the foamed reaction mixture by the same method as the one-shot method. Furthermore, when forming another layer on the foam layer 12, the outer skin of the foam layer, that is, the skin layer may be removed by polishing, or the other layer may be formed as it is without polishing. 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 composed of a hydrophobic and / or hydrophilic polyol and diphenylmethane diisocyanate series isocyanate.

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

As the hydrophilic polyol, for example, polyether polyol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol or the like, or aliphatic such as ethylene glycol, propylene glycol, butylene glycol, pentene glycol or hexene glycol is used. Glycols such as polyalkylene glycols such as glycol, diethylene glycol and dipropylene glycol, and trifunctional or higher polyhydric alcohols such as trimethylolpropane are used as components, and these are added to adipic acid, sebacic acid, suberic acid and brassylic acid. Polyesters such as condensation-type polyester polyols obtained by using polybasic acid components such as aliphatic dicarboxylic acids such as succinic acid and 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.
mg KOH / 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 urethane elastomer obtained 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 urethane elastomer obtained will be large, and if it exceeds 6, the urethane elastomer obtained will be hard, which is not preferable.

The characteristics of the non-foamed layer 13 are not particularly limited, but its hardness is 40 to 85 ° in Asker C hardness, the volume specific resistance value of the non-foamed layer is temperature 22 ° C., humidity 55%, and voltage. 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 the above range, the durability will be insufficient when it wears due to contact with other members, and if it exceeds 2.0 mm, the hardness of the entire roller will be too high and sufficient flexibility cannot be obtained. . Furthermore, the roller surface roughness is JIS 10 point average roughness R
The z-scale is 50 μm or less, more preferably 20 μm or less, and further preferably 10 μm or less.

As the isocyanate for the non-foamed layer 13, diphenylmethane diisocyanate series is used. For example, crude diphenylmethane-4,4 'diisocyanate (crude MDI or polymeric MD)
I)), liquid diphenylmethane-4,4 'diisocyanate such as carbodiimide-modified diphenylmethane-4,4' diisocyanate, uretonimine-modified 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 it is less than 2, the polyurethane elastomer obtained may contaminate the contact product, and if it exceeds 3.5, it becomes brittle, which is not preferable.

The mixing ratio of the polyol and the isocyanate is appropriately 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 contact product, and if it exceeds this range, it becomes brittle, which is not preferable.

The method for producing the non-foamed layer 13 is not particularly limited, but particularly in the case of urethane foam, for example, in the case of the one-shot method, polyol, isocyanate, a conductive material for imparting conductivity, a catalyst. Then, other additives are mixed and stirred at the same time, and the mixture is poured into a mold in which a metal shaft having a roller-shaped foam previously formed as a foam layer is set and cured at 50 to 90 ° C. for several hours. The obtained molded body is ground to a roller. Alternatively, when a cylindrical mold is used, the mold may be left unmolded. Further, in the prepolymer method, a prepolymer is once prepared from a polyol and a difunctional isocyanate, for example, diphenylmethane-4,4 ′ diisocyanate, and then the obtained prepolymer and the same or different polyol and conductivity as those used when the prepolymer is prepared are used. A conductive material for imparting properties, a catalyst, and other additives are simultaneously mixed and stirred, and then a roller is manufactured by the same method as the one-shot method. The non-foamed layer may be polished after the roller is manufactured.

As the conductive material for imparting conductivity to the foamed layer 12 or the non-foamed layer 13, first, as an example of powder, conductive carbon such as Ketjenblack EC and acetylene black, SAF, ISAF, HAF, FE
Rubber carbon such as F, GPF, SRF, FT, MT, etc.
Metals and metal oxides such as color (ink) carbon that has been subjected to oxidation treatment, 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 whose conductivity can be easily controlled with a small amount. Usually, the compounding amount of these conductive materials is 0.5 to 50 parts by weight, particularly 1 to 3 parts by weight with respect to 100 parts by weight of urethane.
It is preferably used in the range of 0 parts by weight.

Examples of the ion conductive substance include sodium perchlorate, lithium perchlorate, calcium perchlorate,
Inorganic ionic conductive material 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-toeimethylammonium methylsulfate, stearamidopropyldimethyl-β-hydroxyethyl-ammonium-dihydrogen phosphate, tetrabutyl Quaternary ammonium perchlorates such as ammonium borofluoride, stearyl ammonium acetate, lauryl ammonium acetate, sulfates,
Examples thereof include organic ionic conductive substances such as ethosulfate salt, methylsulfate salt, phosphate, borofluoride and acetate, or charge transfer complex. Usually, the compounding amount of these conductive materials is suitably used in the range of 0.0001 to 50 parts by weight with respect to 100 parts by weight of urethane.

The urethane elastomer of the non-foamed layer 13 contains various charge control agents such as nigrosine, triaminophenylmethane and cationic dyes, and fine powders such as silicone resin, silicone rubber and nylon for the purpose of controlling transfer efficiency. It 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 1 to 10 parts by weight with respect to 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 may be formed for the purpose of improving the durability of the roller or controlling the transfer efficiency. The synthetic resin component is not particularly limited, but for example, "CM-833" and "CM800" manufactured by Toray Industries, Inc.
Soluble nylon resin such as "0", a solution of a fluororesin in a solvent, water or the like, or an aqueous latex of a fluororesin, for example, "Belflon 10 manufactured by NOF CORPORATION"
"00""Belflon1300" etc., manufactured by Asahi Glass Co., Ltd.,
"Lumiflon LT-FE-3000""Lumiflon 60
0 "," Lumiflon 800 ", etc., manufactured by Daikin Industries, Ltd.," Zeffle LC930 "," Dayer Latex GL "
S-213 "and" GLS-213D "" Polyflon T "
Examples include FE tough coat enamel TC-7400 "and other fluororesins, acrylic resins, urethane-modified acrylic resins, polycarbonate resins, silicone resins, and resins selected from two or more resins selected from melamine resins. Further, the above-mentioned conductive material may be added to the synthetic resin component. As a method for forming the film, a dip coating method, a trans coating method, an in-mold coating method, a roller coating method and the like are suitable.

In the present invention, the volume specific resistance value as the transfer roller is not particularly limited, but the temperature 22
1 × 10 ³ when a voltage of 50 V is applied in an environment of ℃ 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, electric charges may leak to the intermediate transfer member or the photosensitive drum, or the transfer roller itself may be destroyed by the voltage. On the other hand, if the resistance value exceeds 1 × 10 ¹⁰ Ωcm. Therefore, proper discharge cannot be obtained between the transfer roller and the intermediate transfer member or the photosensitive drum.

Since the transfer roller obtained in the present invention has a very good shape following property and has a low hardness, it is possible to obtain a sufficient following property even if the contact nip with respect to a contacted object such as a photoconductor is large. By increasing the nip width with a low contact pressure, it is possible to improve the image quality and increase the transfer speed. The transfer roller of the present invention can be sufficiently brought out by installing it so that the nip width is 3 mm or more, more preferably 5 mm or more with respect to the photoconductor or the like.

[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] Number of functional groups: 3, molecular weight: 5000
100 parts by weight of a prepolymer (hereinafter simply referred to as "part") obtained by reacting tolylene diisocyanate so that NCO% becomes 6.7 with the polyether polyol of
After adding 6.46 parts of 1,4-butanediol, 2 parts of a silicone surfactant, 0.003 part of dibutyltin dilaurate and 2.2 parts of acetylene black, and stirring for 2 minutes using a mixer, the outer diameter was previously calculated. An 8 mm shaft was set, the reaction mixture was poured into a mold preheated to 60 ° C, and the mold was cured at 60 ° C for 12 hours. After demolding, polishing was performed to obtain a roller having an outer diameter of 15 mm and an urethane foam outer layer. A roller having an outer diameter of 16 mm having a two-layer structure in which a hydrophobic urethane elastomer was used as the outermost layer and the inside was urethane foam was obtained from the urethane foam roller thus obtained by the method described below.

First, the hydroxyl value is 47.1 and the number of functional groups is 2.4.
3.1 parts of acetylene black was added to 100 parts of polyisoprene polyol, and degassed under reduced pressure while stirring in vacuum for 30 minutes, and 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, set the urethane foam roller manufactured as described above in advance and inject the reaction mixture into the mold preheated to 60 ° C. Then, it was cured at 90 ° C. for 16 hours, demolded, and then polished to have an outer diameter of 16 mm. The surface of the finished roller is not tacky,
Asker C hardness was 37 ° and resistance was 1 × 10 ⁸ Ω.

In order to test the contamination of the roller on the photosensitive drum, a printer PC-PR1000E / 4 manufactured by NEC Corporation is used.
The rollers were pressed against the photosensitive drum of No. 2 with a load of 500 g on both ends, and left for 5 days at 55 ° C. and 85% humidity. No trace was left on the surface of the photosensitive drum after it was taken out, and there was no effect even when it was mounted on a printer and an image was output.

To see the characteristics of the transfer roller, see FIG.
When images of gray scale, black solid and white solid were observed and stains on the back of the paper were observed by the transfer unit shown in, good image quality was obtained. In addition, when the character image was output, a clear image quality without a blank character was obtained. The above evaluation results are shown in Table 1 together with the results of other examples and comparative examples.

[Table 1]

[Example 2] As the polyol component of the outermost layer urethane elastomer, 100 parts of polyisoprene polyol having a hydroxyl value of 22.0 and a functional number of 2.3 was used as the polyol component, and as the isocyanate component, 5.8 of the same isocyanate as in Example 1 was used. A roller was manufactured in the same manner as in Example 1 except that part of the roller was used, and the same measurement as in Example 1 was performed.

Example 3 As the polyol component of the outermost urethane elastomer, 100 parts of polybutadiene polyol having a hydroxyl value of 105.5 and a functional number of 2.3 was used, and as the isocyanate component, 27.5 parts of the same isocyanate as in Example 1 was used. A roller was manufactured in the same manner as in Example 1 except that it was used, and the same measurements as in Example 1 were performed.

Example 4 As the polyol component of the outermost urethane elastomer, 100 parts of polybutadiene polyol having a hydroxyl value of 32.3 and a functional group of 1.7, and as the isocyanate component, 8.4 parts of the same isocyanate as in Example 1 were used. A roller was manufactured in the same manner as in Example 1 except that it was used, and the same measurements as in Example 1 were performed.

[Example 5] 100 parts of the same polyol as in Example 1 was used as the polyol component of the outermost urethane elastomer, and the NCO% was 2 as the isocyanate component.
A roller was produced in the same manner as in Example 1 except that 13.1 parts of the mixed isocyanate of carbodiimide modified product of diphenylmethane-4,4'-diisocyanate and uretone imine modified product of 9.1 was used, and Example 1 was used. The same measurement was performed.

Example 6 A roller was manufactured by the same method as in Example 1 except that the urethane foam portion inside was manufactured by the method shown below, and the same measurements as in Example 1 were performed. That is, 100 parts of a polyether polyol having a hydroxyl value of 35 and a functional number of 3, and tolylene diisocyanate (T
-80) 26.8 parts, 10 parts of 1,4-butanediol,
2 parts of silicone surfactant, acetylene black 2.8
Parts and 0.003 parts of dibutyltin dilaurate were stirred for 2 minutes using a mixer, and then 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., and the mixture was heated at 60 ° C. for 12 hours. After curing, demolding, polishing,
A roller having an outer diameter of 15 mm and a urethane foam outer layer was obtained.

[Example 7] The same as Example 1 except that the inner urethane foam part was manufactured in the same manner as in Example 6 and the urethane elastomer part in the outermost layer part was manufactured in the following manner. A roller was manufactured by the method, and the same measurement as in Example 1 was performed. That is, 100 parts of polyisoprene polyol having a hydroxyl value of 37 and a number of functional groups of 2.4 and N
Diphenylmethane-4,4'-diisocyanate having a CO% of 33.6 was reacted at 80 ° C for 6 hours to give an NCO% of 2.
9% of prepolymer was obtained. Next, 100 parts of the prepolymer obtained here, a hydroxyl value of 105.5 and a functional group number of 2.
33.4 parts of polybutadiene polyol of 3.7, 3.7 parts of acetylene black and 0.3 parts of dibutyltin dilaurate.
The urethane elastomer part of the outermost layer part was produced with a composition of 001 parts.

[Embodiment 8] The inner urethane foam portion was manufactured in the same manner as in Embodiment 1, and the urethane elastomer portion in the outermost layer portion was manufactured in the same manner as in Embodiment 7. The same measurement as 1 was performed.

[Embodiment 9] The roller obtained by the method described in [Embodiment 1] was mixed with a fluororesin soluble in toluene.
The same measurement as in Example 1 was carried out by immersing the solution in a solution in which it was dissolved by weight% for 10 seconds, pulling the roller, and drying to perform surface treatment.

[Embodiment 10] The roller obtained by the method described in [Embodiment 1] was used with methanol: toluene = 3: 1.
Soluble copolymerized nylon was dissolved in the solvent of 10% to a concentration of 10%, and then carbon was added as a conductive agent in a conductive paint mixed with 20 phr of the nylon at a speed of 1 cm / sec, and a roller was pulled up at the same speed. And dried, and the same measurement as in Example 1 was performed.

[Example 11] Number of functional groups: 3, molecular weight: 500
100 parts of a prepolymer obtained by reacting tolylene diisocyanate with a polyether polyol of 0 to have an NCO% of 6.7, 1,4-butanediol 6.
46 parts, 2 parts of silicone surfactant, 0.003 part of dibutyltin dilaurate and 2.2 parts of acetylene black were added and stirred for 2 minutes using a mixer, and then the outer diameter was 8 in advance.
mm shaft is set and the inner diameter is preheated to 60 ℃ 1
Inject the reaction mixture into a 5 mm mold and apply 12 at 60 ° C.
After curing for an hour, the mold was removed to obtain a urethane foam roller having an outer diameter of 15 mm. A roller having an outer diameter of 16 mm having a two-layer structure in which a hydrophobic urethane elastomer was used as the outermost layer and the inside was urethane foam was obtained on this roller by the method described below.

First, the hydroxyl value is 46.1 and the number of functional groups is 2.4.
3.1 parts of acetylene black was added to 100 parts of polyisoprene polyol, and degassed under reduced pressure while stirring in vacuum for 30 minutes, and 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 defoaming under reduced pressure, the urethane foam roller obtained above was set in advance and poured into a mold having an inner diameter of 16 mm preheated to 90 ° C. Curing was performed at 16 ° C. for 16 hours, and the roller was released from the mold to obtain a roller, and the same measurement as in Example 1 was performed.

[Example 12] As the polyol component of the outermost urethane elastomer, 100 parts of a polyether polyol having a hydroxyl value of 33.7 and a functional group of 3.0, and as an isocyanate component, 9.2 parts of the same isocyanate as in Example 1 were used. A roller was manufactured in the same manner as in Example 1 except that it was used, and the same measurements as in Example 1 were performed.

Example 13 As the polyol component of the outermost layer urethane elastomer, 100 parts of polyether polyol having a hydroxyl value of 112.2 and a functional number of 2.0 was used, and as the isocyanate component, the same isocyanate as in Example 1 was used as 28.8. A roller was manufactured in the same manner as in Example 1 except that part of the roller was used, and the same measurement as in Example 1 was performed.

[Example 14] As the polyol component of the outermost layer urethane elastomer, 100 parts of a polyether polyol having a hydroxyl value of 11.2 and a functional number of 3.0 was used, and as the isocyanate component, the same isocyanate as in Example 1 was used. A roller was manufactured in the same manner as in Example 1 except that part of the roller was used, and the same measurement as in Example 1 was performed.

Example 15 As the polyol component of the outermost urethane elastomer, 100 parts of polyether polyol having a hydroxyl value of 17.3 and a functional group of 4.0 was used as the polyol component, and as the isocyanate component, 4.9 the same isocyanate as in Example 1 was used. A roller was manufactured in the same manner as in Example 1 except that part of the roller was used, and the same measurement as in Example 1 was performed.

Example 16 A conductive urethane foam (EPT-51: Asker C hardness 10 °, volume specific resistance value 1 × 10 ⁴ Ωcm, compression set 8%) manufactured by Bridgestone Co., which was cut out into 25 × 25 × 230 mm. ), Inside diameter 6m
Make a hole of m and insert a hot melt adhesive film with a hole of 6 mm in inner diameter at a pitch of 8 mm so that conduction can be obtained around a metal shaft with an outer diameter of 6 mm.
After heating at 50 ° C. for 30 minutes to bond the shaft and the foam layer, the outer diameter was polished to 16 mm. In the following, the same non-foamed layer as in Example 1 is provided, and the elastic layer has a two-layer structure and an outer diameter of 19.
A roller of mm was obtained and the same evaluation as in Example 1 was performed.

Comparative Example 1 3.1 parts of acetylene black was added to 100 parts of polyisoprene polyol having a hydroxyl value of 47.1 and a functional number of 2.4, and defoamed under reduced pressure with stirring for 30 minutes under vacuum, and then NCO. % 13.7% of crude diphenylmethane-4,4'-diisocyanate and 0.001 part of dibutyltin dilaurate were added, and the mixture was degassed under reduced pressure and stirred for 3 minutes, and then a shaft having an outer diameter of 8 mm was set in advance. Then, the reaction mixture was poured into a mold preheated to 90 ° C. with an inner diameter of 17 mm, cured at 90 ° C. for 16 hours, demolded, and then polished to an outer diameter of 16 mm,
The same measurement as in Example 1 was performed.

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

[Comparative Example 3] Functional group number 3, molecular weight 5000
100 parts of a prepolymer obtained by reacting the above polyether polyol with tolylene diisocyanate so that the NCO% becomes 6.7, 1,4-butanediol 6.46
Parts, 2 parts of silicone surfactant, 0.003 parts of dibutyltin dilaurate and 2.2 parts of acetylene black were added and stirred for 2 minutes using a mixer, and then the outer diameter was 8 mm in advance.
The shaft was set, the reaction mixture was poured into a mold preheated to 60 ° C., and the mold was cured at 60 ° C. for 12 hours. After demolding, 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.

[0061]

That is, the roller of the present invention has at least one layer other than the outermost layer made of foam, and the outermost layer is a urethane comprising a hydrophobic or hydrophilic polyol having a hydroxyl value in a specific range and diphenylmethane diisocyanate series isocyanate. Since it is composed of an elastomer, the hardness of the entire roller can be increased from 10 ° to 70 ° in terms of Asker C hardness without causing the inconvenience of contaminating the photoconductor or the like. The nip width with the photoconductor drum can be widened, and the 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 view showing an example of an image forming apparatus such as a laser printer in which the transfer roller of the present invention is used.

FIG. 3 is a schematic view showing an example of a transfer roller of the present invention.

[Explanation of symbols]

 1 Photosensitive Drum 2 Charging Device 3 Image Exposure System 4 Developing Device 5 Transfer Roller 10 Recording Paper 11 Shaft 12 Foaming Layer (Elastic Layer) 13 Non-foaming Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiro Kawagoe 1302-57 Aobadai, Tokorozawa, Saitama Prefecture

Claims (15)

[Claims] 1. A transfer roller, comprising at least two elastic layers formed on the outer periphery of a shaft, for charging a recording medium to transfer a developer to the recording medium, wherein the elastic layer has an unfoamed layer on the outside. And at least one foamed layer is laminated inside the non-foamed layer, and
A transfer roller having 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. 2. The transfer roller according to claim 1, wherein the non-foamed layer is a urethane elastomer produced mainly from a hydrophobic polyol and an isocyanate of diphenylmethane diisocyanate series by a one-shot method. 3. The transfer roller according to claim 1, wherein the non-foamed layer is a urethane elastomer produced by a prepolymer mainly composed of a hydrophobic polyol and a diphenylmethane diisocyanate series isocyanate and a polyol. 4. The hydroxyl value of the hydrophobic polyol is 15
The transfer roller according to claim 2, wherein the transfer roller has a functional group number of from 1.5 to 3 and 120 mg KOH / g. 5. The transfer roller according to claim 1, wherein the non-foamed layer is a urethane elastomer produced mainly from a hydrophilic polyol and a diphenylmethane diisocyanate series isocyanate by a one-shot method. 6. The transfer roller according to claim 1, wherein the non-foamed layer is a urethane elastomer produced by a prepolymer mainly composed of a hydrophilic polyol and diphenylmethane diisocyanate series isocyanate and a polyol. 7. The hydroxyl value of the hydrophilic polyol is 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 mg KOH / g. 8. A coating film mainly composed of a synthetic resin component is provided on the surface of the non-foamed layer.
The transfer roller according to any one of 1. 9. The synthetic resin component is a soluble nylon resin, an acrylic resin, a urethane-modified acrylic resin, a polycarbonate resin, a silicone resin, a fluororesin, and a resin selected from melamine resins, either alone or in combination of two or more. The transfer roller according to claim 8. 10. The transfer roller according to claim 8, wherein a conductive substance is added to the synthetic resin component. 11. The thickness of the non-foamed layer is 0.1 to 2.0.
The transfer roller according to claim 1, wherein the transfer roller has a size of mm. 12. The flexible layer is a flexible foam selected from the group consisting of polyethylene, polyvinyl chloride, polystyrene, rubber foam, polyvinyl alcohol, viscose, ionomer, urethane, epoxy, phenol, urea, pyranyl, silicone and acrylic. The transfer roller according to claim 1, wherein the transfer roller is provided. 13. The Asker C hardness of the foam layer is 45 °.
Below, the compression set in JIS-K6401 is 10
%, A temperature of 22 ° C., a humidity of 55%, and a volume resistivity value of 1 × 10 ² Ωcm to 1 × when a voltage of 50 V is applied.
It is 10 ⁸ Ωcm, and it is characterized in that
The transfer roller according to any one of 1. 14. The Asker C hardness of the non-foamed layer is 40.
~ 85 °, temperature 22 ° C, humidity 55%, voltage 50V
The volume resistivity when applied is 1 × 10 ³ to 1 × 10.
The transfer roller according to claim 1, wherein the transfer roller has a resistance of ¹¹ Ωcm. 15. 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 the transfer roller.
2. A transfer device using the transfer roller according to any one of 1.