JPH1077358A - Semiconductive foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductive foam low in variance of electric resistivity and excellent in transferability, compressive resistance and photoreceptor contamination resistance, comprising two kinds of high molecular elastomer and electroconductivity-imparting particles which are dispersed more in one of the elastomers than in the other. SOLUTION: This semiconductive foam comprises (A) a high molecular elastomer, (B) another polymeric elastomer, and (C) electroconductive-imparting particles (e.g. highly electroconductive carbon black), wherein the component C is dispersed more in the component A than in the component B. The component A is pref. higher in affinity for the component C than the component B. Preferably, the crosslinking reaction in the component A differs from that in the component B. Specifically, the component A and the component B are pref. an acrylonitrile-butadiene copolymer rubber and an epoxy-contg. acrylic rubber, respectively. This semiconductive foam is obtained by kneading the component A with the component C to produce a master batch followed by crosslinking the component B while kneading the master batch with the component B and then by conducting an expansion molding while crosslinking the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductive foam and a semiconductive foam roll. More specifically, the present invention relates to a semiconductive foam and a semiconductive foam roll used in an electrophotographic printing machine or an electrophotographic copying machine that performs printing or copying using a toner.

[0002]

2. Description of the Related Art In an electrophotographic apparatus such as an electrophotographic copying machine or an electrophotographic printing machine, the outer peripheral surface of a photosensitive drum is uniformly charged, and then the outer peripheral surface of the photosensitive drum is exposed to a print pattern or a copy pattern. A device having a function of forming or developing an electrostatic latent image, forming a toner image by attaching toner to the electrostatic latent image, and transferring the toner image to copying paper or printing paper to perform printing or copying. It is.

In an electrophotographic apparatus, a foaming roll is used as a charging roll for uniformly charging the outer peripheral surface of a photosensitive drum, and as a developing roll for developing an electrostatic latent image on the outer peripheral surface of a photosensitive drum into a toner image. Used as a supply roll for supplying toner to the development roll, as a development blade for regulating the amount of toner carried on the development roll, or as a transfer roll for transferring a toner image to paper or an OHP sheet. .

[0004] Foaming rolls used in electrophotographic machines include:
Rolls made of polyurethane foam are known.
Rolls using urethane rubber, silicone rubber, natural rubber, chloroprene rubber, ethylene propylene diene rubber, and the like are known as foam rolls.

A roll used in an electrophotographic machine is required to have a medium resistance region (semiconductive region) having an electric resistivity in a range of about 10 5 to 10 11 Ω · cm. You. In the conventional foam roll, only the amount of the conductive particles was controlled in order to adjust the electric resistivity. In the high-resistance region or the low-resistance region, since the rate of change of the electrical resistivity with respect to the amount of the conductivity-imparting particles is small, it can be prepared without variation. However, the roll used in the electrophotographic machine is required to have a medium resistance region (semiconductive region) having an electric resistivity in a range of about 10 5 to 10 11 Ω · cm. . In the medium resistance region, the rate of change in the electrical resistivity with respect to the change in the amount of the conductivity-imparting particles is large. In addition, the variation of the electrical resistivity among lots of the foaming rolls increases. Also, if a large amount of the conductivity-imparting particles are blended in order to lower the electric resistivity, the hardness of the roll increases, and it becomes difficult to adjust the hardness and the electric resistivity. Therefore, conventional foam rolls have not been able to obtain satisfactory transferability, photoreceptor contamination, and compression resistance.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductive foam and a semiconductive foam having a small variation in electrical resistivity and excellent properties in transferability, photoreceptor contamination and compression resistance. To provide a role.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above-mentioned object, and as a result, have found that a polymer elastic body (a), a polymer elastic body (b), and a conductivity imparting particle ( c), and by using a foam in which the conductivity-imparting particles (c) are dispersed more in the polymer elastic body (a) than in the polymer elastic body (b), the electric resistivity is reduced. It has been found that the dispersion can be reduced, and a semiconductive foamed roll having practically sufficient characteristics in transferability, photoreceptor contamination and compression resistance can be obtained, and based on this finding, the present invention has been completed. .

Thus, according to the present invention, there is provided (1) a polymer elastic body (a), a polymer elastic body (b), and a conductivity-imparting particle (c), wherein the conductivity-imparting particle is a polymer There is provided a semiconductive foam characterized by being dispersed more in the polymer elastic body (a) than in the elastic body (b).

The following are provided as preferred embodiments of the semiconductive foam of the present invention. (2) The semiconductive foam according to (1), wherein the polymer elastic body (a) has a higher affinity for the conductivity-imparting particles than the polymer elastic body (b). (3) The semiconductive foam according to any one of (1) and (2), wherein a cross-linking reaction of the elastic polymer (a) is different from a cross-linking reaction of the elastic polymer (b). .

According to the present invention, (4) the polymer elastic body (a) and the conductivity imparting particles (c) are kneaded to obtain a master batch, and the master batch and the polymer elastic body (b) are combined. A method for producing a semiconductive foam is provided, in which the polymer elastic body (b) is cross-linked while kneading, and then foamed while the polymer elastic body (a) is cross-linked.

According to the present invention, there is provided (5) a conductive core material and a foam layer covering the outer peripheral surface of the core material, wherein the foam layer is formed of the above (1), (2) or (3). The present invention provides a semiconductive foam roll comprising the foam according to any one of the above (1) to (4).

According to the present invention, (6) the polymer elastic body (a) and the conductivity imparting particles (c) are kneaded to obtain a master batch, and the master batch and the polymer elastic body (b) are combined. Cross-linking the polymer elastic body (b) while kneading, and then foam-forming while cross-linking the polymer elastic body (a) to obtain a foam, and attaching a conductive core material to the foam. A method for making a semiconductive foam roll is provided.

According to the present invention, (7) the semiconductive foamed roll of (5), a core made of a conductive rigid body, and a rubber layer laminated on the outer peripheral surface of the core, wherein the core and the outer periphery of the roll are provided. The electric resistivity between the surface and 10 5 to 10 11 Ω ·
cm, and the ten-point average surface roughness of the outer peripheral surface of the rubber layer is 10 μm.
m and a photosensitive drum whose outer peripheral surface is uniformly charged and exposed to light to remove the charge by exposure, and the semiconductive foam roll, the developing rubber roll and the photosensitive drum rotate respectively. And a developing device in which the semiconductive foam roll and the developing rubber roll are installed in contact with each other, and the developing rubber roll and the photosensitive drum are installed in contact with each other. Further, according to the present invention, (8) the semiconductive foam roll of the above (5), comprising a photosensitive drum whose outer peripheral surface is uniformly charged and whose charge is removed by exposure to light, A transfer device is provided in which the foaming roll and the photoconductor drum can rotate, respectively, and the semiconductive foaming roll and the photoconductor drum are disposed in contact with each other or at an interval capable of passing an object to be transferred. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The semiconductive foam of the present invention is a foam comprising a composition containing a polymer elastic body (a), a polymer elastic body (b), and conductive particles (c). It is.

It is preferable to select a polymer elastic body (a) having a higher affinity for the conductivity-imparting particles than the polymer elastic body (b). Due to the difference in affinity, the polymer elasticity (a) and the polymer elasticity (b) are blended with the conductivity-imparting particles (c) and, when kneaded, the polymer elasticity (a) is spontaneously imparted with conductivity. This is because many particles become ubiquitous. Since the strength of the affinity with the conductivity-imparting particles is relative, even when the same polymer elastic body (1) is used, depending on the type of the other polymer elastic body (2), the polymer elastic body ( In some cases, 1) forms a foam as the polymer elastic body (a) or as the polymer elastic body (b).

The elastic polymer (a) is preferably crosslinked by a different reaction from the crosslinking reaction of the elastic polymer (b). Therefore, it is preferable that the functional group serving as a cross-linking point of the polymer elastic body (a) and the functional group serving as a cross-linking point of the polymer elastic body (b) are different. Examples of the functional group serving as a crosslinking point include a carbon-carbon unsaturated bond, a carboxyl group, an epoxy group, a hydroxyl group, an amino group, a halogen group, and an isocyanate group. Specifically, the polymer elastic body (a) has a carbon-carbon unsaturated bond which can be cross-linked by sulfur or peroxide, and the polymer elastic body (b) is cross-linked by a cross-linking agent other than sulfur and peroxide. Combinations with possible epoxy, carboxyl or halogen groups are preferred.

The elastic polymer (a) includes acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer, acrylonitrile-isoprene-butadiene copolymer, styrene-butadiene copolymer, polybutadiene, polyisoprene, and natural rubber. Chloroprene rubber, ethylene-propylene-diene copolymer, butyl rubber having an unsaturated bond in the molecular chain, and partially hydrogenated products thereof. Of these, acrylonitrile-butadiene copolymer or polybutadiene is preferred. When a low-hardness foam is desired, the liquid rubber is preferably blended in an amount of usually not more than 10% by weight of the whole polymer elastic body.

Examples of the high molecular elastomer (b) include epichlorohydrin rubber, acrylic rubber containing a functional group that serves as a crosslinking point, ethylene-acrylate rubber containing a functional group that serves as a crosslinking point, and epichlorohydrin copolymer. Examples include rubber, epoxidized diene rubber, chloroprene rubber, urethane rubber, chlorosulfonated polyethylene rubber, ethylene-propylene rubber, butyl rubber, fluorine rubber, and silicone. Of these, epoxy group-containing acrylic rubber, epichlorohydrin rubber, and epichlorohydrin-ethylene oxide copolymer rubber are particularly preferred because properties suitable for use in electrophotographic devices are obtained.

The elastic polymer (a) and the elastic polymer (b)
Is usually 20/80 to 80/2 on a weight basis.
0, preferably 30/70 to 70/30. When the ratio of the polymer elastic body (a) is small, the variation in the electrical resistivity tends to be large, and when the ratio of (a) is large, it is difficult to obtain desired flexibility.

The conductivity-imparting particles (c) reduce the electric resistivity of the foam by being dispersed in a material forming the foam. The electrical resistivity of the conductive particles is
Usually, those having a value of 10 5 Ω · cm or less, preferably 10 4 power Ω · cm or less are used. Examples of the conductivity-imparting particles include acetylene black, conductive furnace black, superconductive furnace black, extra conductive furnace black, conductive channel black, furnace black subjected to high-temperature heat treatment, channel black, Ketchan Black EC (manufactured by Ketjen Black International), Highly conductive carbon black such as Ketjen Black EC-60 (manufactured by Ketjen Black International); HAF, ISAF, SAF, SRF, MA
Low conductive carbon black such as F and FEF; graphite; metal powder such as copper powder, silver powder, aluminum powder and nickel powder; Al-doped ZnO, SnO ₂ (antimony oxide doped), TiO ₂ , SnO ₂ (antimony oxide doped) ) Dependent SnO ₂ , SnO ₂ dependent TiO ₂ , K ₂ O · nTiO
₂ / SnO ₂ Sb ₂ O ₆ , SnO ₂ (doped with antimony oxide) complex oxide, and the like. The particle size of the conductivity-imparting particles is usually from 0.01 to 100 μm. These conductive particles can be used alone or in combination of two or more. When two types are used in combination, the highly conductive particles having an electric resistivity of 10 0 Ω · cm or less and an electric resistivity of 10 1 to 10 1.
Low conductivity imparting particles of 0 Ω · cm, especially having an electric resistivity of 5
A combination of a highly conductive carbon black of × 10 -1 Ω · cm or less and a low conductive carbon black or a low conductive metal oxide having an electric resistivity of 10 1 to 10 5 Ω · cm. It is preferable to use it for good control of electric resistivity.

The amount of the conductivity-imparting particles can be appropriately selected in order to adjust the electric resistivity. Specifically, 1 to 100 parts by weight of the polymer elastic body (a) is usually used.
Parts by weight, preferably 3 to 80 parts by weight. When the amount of the conductivity-imparting particles is small, it is difficult to reduce the foam to a desired electric resistivity, and when the amount is large, the electric resistivity is too low and the hardness of the foam tends to be high.

The conductive particles are more dispersed in the elastic polymer (a) than in the elastic polymer (b). The weight of the conductivity-imparting particles dispersed in the polymer elastic body (a) is usually twice or more, preferably 5 times or more the weight of the conductivity-imparting particles dispersed in the polymer elastic body (b). More than double. Since the conductivity-imparting particles are more ubiquitous in the polymer elastic body (a) than in the polymer elastic body (b), the polymer elastic body (a) hardly fluctuates depending on the amount of the conductivity-imparting particles. A polymer elastic body (b) having an electric resistivity in a low resistance region;
The portion has an electrical resistivity in a high-resistance region that does not easily change depending on the amount of the conductivity-imparting particles. By forming a micro-domain structure such as a sea-island structure with the low electric resistivity portion and the high electric resistivity portion, the foam as a whole has an electric resistivity of a medium resistance region, and furthermore, the conductivity imparting particles. A stable electric resistivity of the foam which is not affected by the amount of the polymer is obtained.

The semiconductive foam of the present invention has an average cell diameter of usually 10 to 200 μm, preferably 50 to 15 μm.
0 μm. When the cell diameter is large, clogging of toner or the like occurs, and image formation failure such as fogging of the photoreceptor occurs. When the cell diameter is reduced, problems such as an increase in hardness and a decrease in print density occur.

The semiconductive foam of the present invention has a density of:
Usually, 0.1 to 0.4 g / cm ³ , preferably 0.12
０．３0.3 g / cm ³ . If the density is low, clogging of the toner occurs to cause defective image formation. When the density is high, the rotational load of the roll increases.

The semiconductive foam has a Asker hardness F
However, it is usually 30 to 90 degrees, preferably 40 to 85 degrees. The Asker hardness C is usually 0.1 to 50.
Degrees, preferably 0.5 to 40 degrees. Asker hardness F
When the Asker hardness C is low, the durability decreases. When the Asker hardness F and the Asker hardness C are high, the rotational load of the roll increases. Further, by setting the hardness F and the hardness C within this range, the efficiency of scraping the toner is improved, and problems such as generation of ghost and reduction in print density are eliminated.

The semiconductive foam has an electric resistivity of usually 10 3 to 10 13 Ω · cm, preferably 1 to 10 13 Ω · cm.
It is 0 to the power of 10 to 11 to the power of 11 Ω · cm. The electrical resistivity can be adjusted by controlling the amount of the conductivity-imparting particles and the ratio of the polymer elastic body (a) and the polymer elastic body (b).

The semiconductive foam of the present invention is not particularly limited by its manufacturing method. In general, a method is used in which after the conductivity imparting particles are dispersed in the polymer elastic body (a), the polymer elastic body (b) is kneaded and foamed.

Elastic polymer (a), elastic polymer (b)
And to knead or disperse the conductivity imparting particles, usually,
A kneader such as a roll, an extruder or a Banbury mixer may be used, or a latex or a slurry obtained by polymerizing the polymer elastic body (a) or the polymer elastic body (b) may be mixed. May be performed by a method of co-coagulation.

In order to use the semiconductive foam for a roll or a blade of an electrophotographic apparatus, an appropriate hardness is required.
In order to adjust the hardness, the elastic polymer (a) and the elastic polymer (b) are crosslinked. As a preferred method of crosslinking, the polymer elastic body (a) and the conductivity-imparting particles (c) are kneaded to obtain a masterbatch, and the masterbatch and the polymer elastic body (b) are kneaded. Elastic polymer (b)
And then foaming the elastic polymer (a). In order to apply the present invention to an electrophotographic apparatus, it is preferable to crosslink the elastic polymer (a) when foaming the elastic polymer (a).

The method of crosslinking and foaming the polymer elastic body (a) or the polymer elastic body (b) is not particularly limited, but a compound containing a crosslinking agent described later is heated or irradiated with high frequency to generate heat. Do it. In order to make foaming and cross-linking uniform and to make the size of foam cells fine and uniform, a method using high-frequency irradiation is preferable.

A suitable crosslinking agent used for crosslinking the elastic polymer (b) is appropriately selected according to the type of the elastic polymer (b). For example, when the polymer elastic body (b) is epichlorohydrin rubber, ethylenediamine;
Polyamines such as hexamethylenediamine and the like and salts thereof; 2-mercaptoimidazolines such as 2-mercaptoimidazoline, 4-methyl-2-mercaptoimidazoline and 5-ethyl-4-butyl-2-mercaptoimidazoline 2-mercaptopyrimidines;
Mercaptotriazines such as 1,3,5-trithiocyanuric acid, 2-butylamino-4,6-dimercapto-s-triazine, and thioureas such as thiourea, dibutylthiourea, and triethylthiourea. Can be.

When the polymer elastic body (b) is an epoxy group-containing rubber, organic elastomers such as isocyanuric acid, octadecyltrimethylammonium bromide, diphenylurea, hexamethylenetetramine, p, p'-diaminediphenylmethane, ammonium benzoate and the like can be used. Amine compounds such as ammonium carboxylate; hexamethylenediamine carbamate; N, N'-dicinnamylidene-1,6-hexadiamine;4,4'-methylenebis-(2-chloroamylin); toluylene diisocyanate; diphenylmethane diisocyanate Nath, naphthylene-
Examples thereof include polyisocyanate compounds such as 1,5-diisocyanate.

When the elastic polymer (b) is an acrylic rubber or an ethylene-acrylate rubber, triethylenetetramine, triethyltrimethylenetriamine,
Amine compounds such as hexamethylene diamine carbamate are exemplified.

When the elastic polymer (b) is a chloroprene rubber, zinc oxide, magnesium oxide and the like can be mentioned, and 2-mercaptoimidazoline and the like can be used in combination as a crosslinking accelerator.

When the elastic polymer (b) is a urethane rubber, bismaleimide, biscitraconamide and the like can be used.

When the elastic polymer (b) is a chlorosulfonated polyethylene rubber, examples thereof include magnesium oxide, lead monoxide, lead maleate trichloride, abietic acid, and hydrogenated rosin.

When the elastic polymer (b) is butyl rubber, examples thereof include quinone-based crosslinking agents such as p-benzoquinonedioxime and benzoylquinonedioxime, and resin crosslinking agents.

When the elastic polymer (b) is a fluororubber, examples thereof include hexamethylenediaminecarbamate and ethylenediaminecarbamate.

The amount of the cross-linking agent for cross-linking the elastic polymer (b) varies depending on the type of the elastic polymer (b) and the type of the cross-linking agent. On the other hand, it is usually 1 to 15 parts by weight, preferably 2 to 10 parts by weight. The cross-linking agents can be used alone or in combination. When the polymer elastic body (b) is a mixture composed of plural kinds of combinations, it is preferable to use plural kinds of cross-linking agents according to the kind of the polymer elastic body.

Suitable crosslinking agents used for crosslinking the elastic polymer (a) include sulfur; thiuram such as tetramethylthiuram disulfide and tetrabutylthiuram disulfide; dicumyl peroxide, di-t-butyl peroxide, -Organic peroxides such as menthane hydroperoxide and cumene hydroperoxide.

The amount of the crosslinking agent used for crosslinking the elastic polymer (a) varies depending on the type of the elastic polymer (a) and the type of the crosslinking agent, but 100 parts by weight of the elastic polymer (a) is used. To 0.5 to 15 parts by weight, preferably 1 to
To 10 parts by weight.

The semiconductive foam of the present invention may contain a crosslinking accelerator, a crosslinking accelerator, an antioxidant, a dispersant, and the like, if necessary.

The semiconductive foam of the present invention can be used not only for the foam layer of the semiconductive roll described below but also for a developing blade used for regulating the amount of toner carried on the developing roll. .

The semiconductive foam roll of the present invention comprises a conductive core material and a foam layer covering the outer peripheral surface of the core material, wherein the foam layer is made of the semiconductive foam. is there.

In the semiconductive foam roll of the present invention, the core material is formed of a conductive rigid body, specifically, a metal such as copper, iron, stainless steel, aluminum and nickel. The core material usually has a cylindrical shape with the same outer diameter from one end to the other, but the wear of the other roll or the end of the foam roll due to the contact of the foam roll with another roll is reduced. In order to achieve this, it is preferable that the outer diameter of the end portion of the core material be smaller than the central portion in the axial direction of the core material. It is preferable to increase the surface roughness of the outer peripheral surface of the core material in order to increase the adhesive strength with the foam layer.

The outer peripheral surface of the semiconductive foam roll can be coated with a resin or the like for adjusting electric resistivity or adjusting surface roughness or frictional resistance.

The electric resistivity between the core and the outer peripheral surface of the roll is 10 ³ to 10 ¹¹ Ω · cm, preferably 10 ⁴ to 10 ¹⁰
Ω · cm.

The method for producing the semiconductive foam roll of the present invention is not particularly limited, but the polymer elastic body (a) and the conductivity-imparting particles (c) are kneaded to obtain a masterbatch. The polymer elastic body (b) is cross-linked while kneading with the elastic body (b), and then foam-forming is performed while the polymer elastic body (a) is cross-linked to obtain a foam. A method of attaching a material is preferable.

The joining between the foam and the core material can be easily carried out by grinding the foam and bonding it to the core material. The outer diameter of the core material is larger than the inner diameter of the part where the core material of the foam is attached, because the bonding strength between the core material and the foam becomes stronger, so the joint is broken and the roll slips on the core material. This is preferable because rotation is prevented and image defects can be prevented from occurring.

The semiconductive foam roll according to the present invention is coated with a resin such as polyurethane or the like, in order to adjust the frictional resistance, surface roughness, surface electrical resistivity or hardness of the outer peripheral surface of the foam layer, Etc. can be irradiated.

The semiconductive foam roll of the present invention is a developing roll for developing an electrostatic latent image on the outer peripheral surface of the photosensitive drum into a toner image as a charging roll 5 for uniformly charging the outer peripheral surface of the photosensitive drum. The roll 6 can be used as a supply roll 8 for supplying toner to a developing roll, or as a transfer roll 7 for transferring a toner image to paper or an OHP sheet. In particular, it can be suitably used for a supply roll or a transfer roll.

FIG. 1 is a view showing a developing device or a transfer device of the present invention. The developing device of the present invention includes the semiconductive foaming roll (hereinafter referred to as a supply foaming roll), a developing roll, and a photosensitive drum. The photosensitive drum is
The outer peripheral surface is uniformly charged by being brought into contact with a charging device such as a charging roll, and the charge is removed by exposure.

The supply foaming roll, the developing roll, and the photosensitive drum are fixed so as to be rotatable. The supply foaming roll and the developing roll are fixed so as to be in contact with each other. Further, the developing roll and the photosensitive drum are fixed so as to be in contact with each other. In addition, a drive device for rotating the supply foaming roll, the photosensitive drum, and the developing roll, respectively, is usually provided (not shown).

The rotation direction of the photosensitive drum and the rotation direction of the developing roll are usually set to be opposite to each other (so as to rub in the same direction on the contact surface). The rotation direction of the supply foaming roll and the rotation direction of the developing roll are usually set to the same rotation direction (so as to rub in opposite directions on the contact surface). The peripheral speed is set so that the toner adheres sufficiently to the photoconductor.
It is preferable to rotate the developing roll at a peripheral speed of 1.5 to 3 times the peripheral speed of the photosensitive drum in order to increase the efficiency of cleaning the residual toner not transferred by the transfer device described later with the developing roll. . Further, it is preferable to rotate the supply foaming roll at a peripheral speed of 0.4 to 0.9 times the peripheral speed of the developing roll.

A voltage is usually applied to the supply foaming roll, the photosensitive drum, and the developing roll. Regarding the voltage applied to the photosensitive drum and the developing roll, the relationship between the surface potential (Vc) of the photosensitive drum and the surface potential (Vd) of the developing roll is such that the absolute value of (Vc−Vd) is 50 volts or more. To do. By setting the applied voltage to the above conditions, development and cleaning can be performed simultaneously and efficiently.

Usually, a developing blade for controlling the layer thickness and charging state of the toner adhered to the surface of the developing roll is in contact with the developing roll. Normally, a voltage is applied to the developing blade and the supply foaming roll. The voltages applied to the developing blade and the supply foaming roll are the surface potential of the developing blade (Vb), the surface potential of the supply foaming roll (Vs), and the surface potential of the developing roll (Vd).
Is expressed by Equation 1. The charging of the toner becomes uniform, and the toner can be supplied efficiently.

[0057]

(Equation 1)

The toner adhered to the photosensitive drum by the developing roll is transferred to a toner image on paper or a resin sheet by a transfer device. The transfer device includes a transfer roll,
Examples include a transfer belt and a corona discharge transfer device.

The ten-point average roughness (Rz ₁ ) of the developing roll used in the developing device of the present invention is 10 μm or less, preferably 2 to 10 μm.
9 μm. Rz ₁ is preferably smaller,
Since it is difficult to make z ₁ close to 0, the lower limit is usually about 0.3 μm.

Furthermore, the ratio of the ten-point average roughness in the circumferential direction (Rz ₂ ) / the ten-point average roughness in the axial direction (Rz ₁ ) of the developing roll used in the present invention is 0.9 to 1.2. Is preferred. Rz ₂ / Rz is a ratio of ₁ becomes higher as the print density becomes large halftone (dot reproducibility of printing) is reduced.
Conversely, the print density at which the ratio of Rz ₂ / Rz ₁ becomes small and the dot reproducibility of print decrease. The ten-point average roughness (Rz ₁
And Rz ₂ ) are the average of the heights of the highest to fifth peaks and the depths of the deepest to fifth valleys in the portion extracted by the reference length from the cross-sectional curve of the rubber roll surface. The difference from the average value is expressed in μm.

The electrical resistivity of the rubber layer of the developing roll is usually 10 ⁶ to 10 ¹¹ Ω · cm, preferably 10 ⁶ to 10 ¹⁰
Ω · cm. By setting the electrical resistivity in this range, the toner charge becomes high and uniform, a good print density is obtained, and the dot reproducibility is also improved.

The material of the rubber layer of the developing roll has rubber elasticity. Materials having rubber elasticity include styrene-butadiene rubber, acrylonitrile-butadiene rubber, isoprene rubber, chloroprene rubber, ethylene-
Examples thereof include propylene-diene rubber, epichlorohydrin rubber, butyl rubber, and acrylic rubber. Of these, acrylonitrile-butadiene rubber and epichlorohydrin rubber are preferable because the rubber layer has a uniform electric resistivity and can uniformly charge the toner, so that image defects such as fogging hardly occur.

The transfer device of the present invention comprises the above-mentioned semiconductive foam roll (hereinafter referred to as a transfer foam roll) and a photosensitive drum, and the transfer foam roll and the photosensitive drum can rotate and contact each other. Alternatively, the transfer member is provided with an interval capable of passing the transfer object. The transfer device is a device for copying a toner image obtained by developing an electrostatic latent image by a developing device onto a transfer target such as paper or an OHP sheet.

Normally, a voltage is applied to the transfer foaming roller. The nip length of the contact portion between the transfer foaming roll and the photoconductor drum is usually set to facilitate the passage of the transferred object and to make the transfer excellent.
The thickness is set to 0.01 to 10 mm, preferably 0.05 to 5 mm.

The toner applicable to the developing device or the transfer device of the present invention is not particularly limited, but a spherical non-magnetic one-component toner is preferably used. The spherical toner has a volume average particle diameter (dv) of 3 to 15 μm, preferably 5 to 10 μm. A suitable spherical toner has the above volume average particle diameter, and further has a volume average particle diameter (dv) and a number average particle diameter (d).
n) is a ratio (dv / dn) of 1 to 1.4, and a value (Sc / Sr) obtained by dividing the area (Sc) of a circle whose diameter is the absolute maximum length of the particle by the substantial projected area (Sr) of the particle. ) Is 1 to 1.3.
It is. Spherical toners that can be more suitably applied include a specific surface area (A) [m ² / g] according to the BET method and a number average particle diameter (d).
n) The product (A × dn × D) of [μm] and the true specific gravity (D) falls within the range of 5 to 10, and the charge amount (Q) [μc /
g] and the specific surface area (A) ratio (| Q | / A) is 4
0 to 150. The spherical toner can be usually obtained by a polymerization method. The spherical toner may be a uniform polymer or a core-shell type comprising a core made of a polymer having a low glass transition temperature and a shell made of a polymer having a high glass transition temperature. It may be. In addition, in order to cope with color printing, pigments of each color other than black can be mixed with the spherical toner.

[0066]

The present invention will be described in more detail by way of examples. The evaluation test method performed in this example is as follows.

[Residual transfer] After continuous printing of 2,000 sheets, the residual transfer (toner that could not be completely transferred) on the photosensitive drum in the black solid portion was peeled off with an adhesive tape, and the tape was stuck on white paper. The reflectance was measured by a whiteness meter, and the difference from the reflectance of a product obtained by attaching only the adhesive tape to white paper was determined. ○ ・ ・ ・ The difference is less than 15% △ ・ ・ ・ The difference is 15% or more and less than 20% × ・ ・ ・ 20% or more

[Transfer Unevenness] After 2,000 sheets of continuous printing were performed, the print density of the solid black portion was measured using a Macbeth densitometer, and the print density at 10 points was evaluated from the minimum value to the maximum value. .

[Photoconductor contamination] The transfer foaming roll was loaded with a load of 50.
0 ° C. and contact with the photosensitive drum at 45 ° C.
After being left for 3 weeks in an environment of 0% RH, the presence or absence of photoconductor contamination was visually checked.・ ・ ・: No contamination was observed after 3 weeks. Δ: Streak-like contamination was observed after 2 weeks to 3 weeks. ×: Contamination was observed before the lapse of two weeks.

[Compression resistance] The transfer foam roll has a deformation ratio of 20.
%, The transfer foam roll was brought into contact with the photoreceptor drum, left in an environment of 45 ° C. and 80% RH for 3 weeks, and the compression set of the roll was determined. ○: Compression set is less than 10% △: Compression set is 10% or more and less than 20% ×: Compression set is 20% or more

Example 1 50 parts by weight of an acrylonitrile-butadiene copolymer rubber and 4 parts by weight of Ketjen Black EC (conductive carbon manufactured by Ketjen Black International) were added, and the mixture was kneaded using a Banbury mixer. After adding 50 parts by weight of the contained acrylic rubber and kneading in the same manner, 0.36 parts by weight of isocyanuric acid and 1.08 parts by weight of octadecyltrimethylammonium bromide were added, and the mixture was heated to 150 ° C. using a Banbury mixer.
The mixture was kneaded for 0 minute to crosslink the epoxy group-containing acrylic rubber. Next, 0.8 parts by weight of dicumyl peroxide, p,
p'-oxybis (benzenesulfonyl hydrazide)
4 parts by weight (manufactured by Sankyo Kasei Co., Ltd.) are added, kneaded, extruded into a tube having an inner diameter of about 6 mm and an outer diameter of about 15 mm, and subjected to a continuous microwave vulcanizer (UHF.C).
Vulcanization and foaming of the acrylonitrile-butadiene copolymer were performed using V) to obtain a semiconductive foam. UH
F. CV is UHF heating section and secondary heating section (hot blast stove HAV)
In the UHF heating section, the temperature is 180 ° C.
1. F frequency 915 MHz, output 0.3 kw, transit time
In the secondary heating section, the temperature was 200 ° C. and the passage time was 5 minutes.

After applying an adhesive to a stainless steel core material having an outer diameter of 6 mm and a length of 280 mm, the core material is inserted into the tube cavity of the foamed material, and then placed at 120 ° C. in an environment of 30 ° C.
After standing for a minute, the foam and the core material were joined, and the outer peripheral surface of the foam was polished to obtain a semiconductive foam roll having an outer diameter of 15 mm and a length of 250 mm.

The above-described evaluation was performed by attaching this semiconductive foam roll as a transfer roll of the electrophotographic apparatus shown in FIG. Table 1 shows the results.

Example 2 A hot air stove HAV continuous vulcanizer was used in place of the compounding recipe shown in Table 1 and in place of the microwave continuous vulcanizer to obtain a temperature of 2
A semiconductive foam and a semiconductive foam roll were obtained in the same manner as in Example 1 except that the test was performed at 20 ° C. and a passage time of 5 minutes. Table 1 shows the evaluation results of the semiconductive foam roll.

Example 3 A foam and a foam roll were obtained in the same manner as in Example 1 except that the composition was as shown in Table 1. Next, a glass transition temperature of 40
80 ° C. polyurethane resin aqueous dispersion (solid content 20%) 80
The foamed roll is immersed in a liquid obtained by mixing and dispersing 20% by weight of tin oxide and 20% by weight of tin oxide using a ball mill pot, and dried to form an inner coating of about 50 μm on the outer peripheral surface of the foamed roll. The foamed roll having the film formed thereon is immersed in an aqueous dispersion of polyurethane resin (solid content: 20%) at a temperature of 72 ° C., and dried to form an outer film of about 15 μm on the outer peripheral surface of the foamed roll. In an environment of ℃
It was left for 0 minutes to obtain a semiconductive foam roll. Table 1 shows the evaluation results of the semiconductive foam roll.

Example 4 A semiconductive foam and a semiconductive foam roll were obtained in the same manner as in Example 3, except that the formulation shown in Table 1 was used. Table 1 shows the evaluation results of the semiconductive foam roll.

[0077]

[Table 1]

Comparative Examples 1 and 2 Foam rolls were obtained in the same manner as in Example 4 except that the formulation shown in Table 2 was used. Table 1 shows the results of these evaluations.

[0079]

[Table 2]

[0080]

According to the present invention, it is possible to obtain a semiconductive foam and a semiconductive foam roll having small variations in electrical resistivity and practically sufficient characteristics in transferability, photoreceptor contamination and compression resistance. be able to.

[Brief description of the drawings]

FIG. 1 is a diagram showing an electrophotographic apparatus.

[Explanation of symbols]

 4: Photoreceptor drum 5: Charging roll 6: Developing roll 7: Transfer roll 8: Supply roll 9: Developing blade

Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location // C08L 21:00 (72) Inventor Haruhiko Takahashi 1-2-1 Yoko, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Zeon Nihon Inside the General Development Center Co., Ltd.

Claims (8)

[Claims] 1. An elastomer comprising a polymer elastic body (a), a polymer elastic body (b), and a conductivity-imparting particle (c), wherein the conductivity-imparting particle has a higher molecular weight than the polymer elastic body (b). Elastic body (a)
A semiconductive foam, characterized in that the foam is dispersed in a larger amount. 2. The semiconductive foam according to claim 1, wherein the polymer elastic body (a) has a higher affinity for the conductivity-imparting particles than the polymer elastic body (b). 3. The semiconductive foam according to claim 1, wherein a crosslinking reaction of the elastic polymer (a) is different from a crosslinking reaction of the elastic polymer (b). 4. A polymer batch is kneaded with the polymer elastic body (a) and the conductivity-imparting particles (c) to obtain a masterbatch. A method for producing a semiconductive foam, comprising crosslinking the body (b) and then foaming while crosslinking the elastic polymer (a). 5. A conductive core material, and a foam layer covering an outer peripheral surface of the core material, wherein the foam layer is provided.
A semi-conductive foam roll, comprising the foam according to any one of the preceding claims. 6. A polymer elastic body (a) and conductive imparting particles (c) are kneaded to obtain a masterbatch, and the masterbatch and the polymer elastic body (b) are kneaded to form a polymer elastic body. (B) cross-linking and then foam-forming while cross-linking the polymer elastic body (a) to obtain a foam, and a conductive core material is attached to the foam; Recipe. 7. The semiconductive foamed roll according to claim 5, comprising a core made of a conductive rigid body and a rubber layer laminated on the outer peripheral surface of the core, and the electric resistance between the core and the outer peripheral surface of the roll. The developing rubber roll having a rate of 10 ⁵ to 10 ¹¹ Ω · cm and a ten-point average surface roughness of the outer peripheral surface of the rubber layer of 10 μm or less, and the outer peripheral surface are uniformly charged and exposed to charge to remove the charge. The semiconductive foam roll, the developing rubber roll and the photosensitive drum can rotate respectively, and the semiconductive foam roll and the developing rubber roll are placed in contact with each other, and the developing rubber roll and A developing device that is installed in contact with a photosensitive drum. 8. The semiconductive foam roll according to claim 5, comprising a photosensitive drum whose outer peripheral surface is uniformly charged and whose charge is removed by exposure to light, the semiconductive foam roll and the photosensitive drum. Is a transfer device in which a semiconductive foaming roll and a photosensitive drum are rotatable, and are provided at an interval so as to allow an object to be transferred to pass therethrough.