JP2021051232A - Charging roller for electrophotographic devices - Google Patents

Abstract

To provide a charging member for electrophotographic devices, which suppresses adhesion of untransferred toner and toner-derived components to a charging roller, minimizes the effect of adhesion even when it occurs, and prevents overcharging of a photosensitive drum by electrical charge of untransferred toner and toner-derived components.SOLUTION: A charging roller 10 for electrophotographic devices is provided, comprising an elastic layer 14 and a surface layer 16 formed to surround the elastic layer 14. The surface layer 16 contains (a) an amorphous polyester binder polymer, (b) a carbon black, (c) porous particles, and (d) an acrylic modifier having at least one group selected from silicone groups and fluorine-containing groups.SELECTED DRAWING: Figure 1

Description

The present invention relates to a charging roll for an electrophotographic apparatus that is suitably used in an electrophotographic apparatus such as a copier, a printer, or a facsimile that employs an electrophotographic method.

When copying or printing with an electrophotographic apparatus, a document image is formed as an electrostatic latent image on a photosensitive drum charged by a charging roll, and toner charged by a developing member is adhered to the electrostatic latent image to form a toner image. , It is done by transferring the toner image to the copying paper. The toner that has not been transferred to the copying paper is scraped from the photosensitive drum by the cleaning blade. After that, the photosensitive drum is charged again by the charging roll. The charging roll is designed on the assumption that the untransferred toner is scraped off by the cleaning blade.

Japanese Unexamined Patent Publication No. 4-299355

As part of the miniaturization of electrophotographic equipment, a configuration that does not use a cleaning blade is being studied. If the cleaning blade is not used, the charged roll comes into contact with the photosensitive drum with untransferred toner and components derived from the toner remaining on the surface of the photosensitive drum. The conventional charging roll is designed on the premise that the untransferred toner and the components derived from the toner are scraped off by the cleaning blade, and is not designed in consideration of the adhesion of the untransferred toner and the components derived from the toner. Therefore, when the photosensitive drum is charged, untransferred toner or a component derived from the toner adheres from the photosensitive drum to the charging roll. The components derived from the untransferred toner and the toner attached to the charging roll are charged, and when the photosensitive drum is charged by the charging roll to which the components derived from the untransferred toner and the toner are attached, the photosensitive drum is derived from the untransferred toner and the toner. An overcharge phenomenon of the photosensitive drum occurs due to the electric charge of the component, which causes an image defect. When a layer of a silicone or fluorine polymer is formed on the outermost surface of the charging roll against the adhesion of untransferred toner or components derived from the toner, the effect of suppressing the physical adhesion is suppressed, but the effect of suppressing the electrostatic adhesion is suppressed. Is low, and its inhibitory effect is low, especially under high temperature and high humidity.

In Patent Document 1, in a charging roll having a conductive elastic layer on a conductive support, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyethyleneimine, and starch are selected on the conductive elastic layer. It is described that it has a polymer layer containing a water-soluble polymer. However, Patent Document 1 changes the surface layer material of the charging member from rubber or polyurethane to a water-soluble polymer so that the contact surface between the photoconductor and the charging member does not stick, and is not scraped off. It does not suppress the overcharging phenomenon of the photosensitive drum due to the charge of the untransferred toner or the component derived from the toner.

The problem to be solved by the present invention is to suppress the adhesion of untransferred toner and components derived from the toner to the charging roll, and to minimize the influence on the image even if there is adhesion, the untransferred toner and the untransferred toner. An object of the present invention is to provide a charging roll for an electrophotographic apparatus in which an overcharging phenomenon of a photosensitive drum due to a charge of a component derived from toner is suppressed.

In order to solve the above problems, the charging roll for an electrophotographic apparatus according to the present invention comprises a shaft body, an elastic body layer formed on the outer periphery of the shaft body, and a surface layer formed on the outer periphery of the elastic body layer. The gist is that the surface layer includes the following (a) to (d).
(A) Amorphous polyester binder polymer (b) Carbon black (c) Porous particles (d) Acrylic modifier having at least one selected from silicone group and fluorine-containing group

In (a), the number average molecular weight is preferably in the range of 1000 to 15000.
In the above (a), Tg is preferably in the range of 50 to 70 ° C.

According to the charging roll for electrophotographic equipment according to the present invention, the surface layer contains (a) an amorphous polyester-based binder polymer, (b) carbon black, (c) porous particles, and (d) a silicone group and fluorine. Since it has an acrylic modifier having at least one selected from the groups, it suppresses the adhesion of untransferred toner and toner-derived components to the charging member, and even if it adheres, it affects the image. It should be minimized, and the overcharge phenomenon of the photosensitive drum due to the charge of the untransferred toner and the components derived from the toner can be suppressed.

When the above (a) is an amorphous polyester binder polymer, the permittivity of the deposits composed of untransferred toner and components derived from the toner is similar to the permittivity of the binder component used for the surface layer of the charging roll. Even if untransferred toner or a component derived from the toner adheres, the influence on the image can be minimized.
Further, when the above (a) is an amorphous polyester binder polymer, it is difficult for untransferred toner and components derived from the toner to adhere to the surface of the charging roll.
Further, when the above (b) is carbon black, the resistance value of the surface layer of the charging roll can be made uniform, so that the overcharging phenomenon of the photosensitive drum can be suppressed.
Further, when the (c) is porous particles, the dispersibility is higher than that of the non-porous particles and the particles can be uniformly dispersed in the surface layer of the charging roll, so that the overcharging phenomenon of the photosensitive drum can be suppressed. ..
Further, when the above (d) is an acrylic modifier having at least one selected from a silicone group and a fluorine-containing group, untransferred toner and components derived from the toner are unlikely to adhere to the surface of the charging roll.
Further, by using the above (a) and the above (d) in combination, the (d) is unevenly distributed near the surface, and the (a) is present under the (d) in the surface layer (on the elastic layer side). , It is effective against physical and electrostatic adhesion of untransferred toner and components derived from toner.

When the number average molecular weight of (a) is in the range of 1000 to 15000, the surface hardness of the charged roll can be optimized and the coating film property is also excellent. Also, Tg is 5
When the temperature is in the range of 0 to 70 ° C., the surface hardness of the charging roll can be made optimum, and the effect of suppressing the overcharging phenomenon of the photosensitive drum due to the charge of the untransferred toner or the component derived from the toner is improved.

FIG. 3A is a schematic external view (a) of a charging roll for an electrophotographic apparatus according to an embodiment of the present invention, and is a sectional view (b) taken along the line AA. It is a schematic appearance figure of the surface layer cross section of the charge roll which concerns on one Embodiment of this invention. It is a schematic appearance figure of the charge amount difference measurement of the charge roll which concerns on one Embodiment of this invention.

Hereinafter, the present invention will be described in detail. The charging roll for an electrophotographic apparatus according to the present invention is not particularly limited in shape and layer structure as long as it charges an object to be charged such as a photosensitive drum.

Charging roll for electrophotographic equipment according to the present invention (hereinafter, may be simply referred to as a charging roll).
Will be described in detail. FIG. 1 is a schematic external view (a) of a charging roll for an electrophotographic apparatus according to an embodiment of the present invention, and a cross-sectional view taken along the line AA (b). FIG. 2 is a cross-sectional view of the vicinity of the surface layer of the charging roll for electrophotographic equipment according to the embodiment of the present invention.

The charging roll 10 includes a shaft body 12, an elastic body layer 14 formed on the outer periphery of the shaft body 12, and a surface layer 16 formed on the outer periphery of the elastic body layer 14. The elastic layer 14 is a layer that is a base of the charging roll 10. The surface layer 16 is a layer that appears on the surface of the charging roll 10. The surface layer 16 contains the porous particles 18.

The surface layer 16 includes the following (a) to (d).
(A) Amorphous polyester binder polymer (b) Carbon black (c) Porous particles (d) Acrylic modifier having at least one selected from silicone group and fluorine-containing group

As the above (a), those having a number average molecular weight in a specific range can be preferably used. The number average molecular weight of (a) is preferably in the range of 1000 to 15000. More preferably, the range is 4000 to 12000. More preferably, the range is 6000 to 10000.
As a result, the surface hardness of the charged roll can be made optimum, and the coating film property is also excellent, and the binder polymer of (a) forming the surface layer is inside the porous particles of (c). It penetrates and improves the adhesion between the binder polymer on the surface layer and the porous particles.

As described in (a), those having a Tg in a specific range can be preferably used. (A)
Tg is preferably in the range of 50 to 70 ° C. More preferably, the temperature range is 55 to 70 ° C. More preferably, the temperature is in the range of 60 to 70 ° C.
As a result, the surface hardness of the charging roll can be made optimum, and the effect of suppressing the overcharging phenomenon of the photosensitive drum due to the charge of the untransferred toner or the component derived from the toner is improved.

The above (a) may be linear or branched, but the linear shape is preferable from the viewpoint that the dielectric constant of the surface layer 16 of the charging roll 10 can be easily controlled uniformly.
Further, it may be soluble or insoluble in a solvent, but it is preferably soluble from the viewpoint of easily ensuring the coatability of the charged roll as the surface layer. The solvent is not particularly limited, but methyl ethyl ketone is preferable.
Further, the hydroxyl value is preferably 30 KOHmg / g or more.
This is because when the hydroxyl value is 30 KOHmg / g or more, the dispersion of the above (b), the above (c), and the above (d) is improved.

Examples of the amorphous polyester binder polymer (a) mentioned above include those obtained by reacting a dibasic acid (a1) with a diol (a2) as an essential component.

The dibasic acid (a1) is a fat such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, hexahydrophthalic acid, 1,4-cyclohexanedicarboxylic acid and the like. Group dicarboxylic acid;
Maleic acid, maleic anhydride, citraconic acid, dimethylmaleic acid, cyclopentene-1
, 2-Dicarboxylic acid, 1-cyclohexene-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, fumaric acid, mesaconic acid, itaconic acid, glutaconic acid and other aliphatic unsaturated dicarboxylic acids Acids: Examples include aromatic dicarboxylic acids such as phthalic acid, phthalic anhydride, terephthalic acid, isophthalic acid and orthophthalic acid. Each of these may be used alone, or two or more types may be used in combination.

The diol (a2) is, for example, ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1. , 3-Propylenediol, 1,
4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol,
An aliphatic diol such as 1,5-pentanediol, 3-methyl 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-bis (hydroxymethyl) cyclohesan; polyoxyethylene glycol, poly Ether glycol such as oxypropylene glycol; the aliphatic diol, ethylene oxide, propylene oxide, etc.
Modified polyether polyol obtained by ring-open polymerization with various cyclic ether bond-containing compounds such as tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, allyl glycidyl ether; the aliphatic diol and ε. -Lactone-based polyester polyol obtained by polycondensation reaction with various lactones such as caprolactone; bisphenol A, bisphenol B
, Bisphenol F, Bisphenol S and the like; Examples thereof include alkylene oxide adducts of bisphenol obtained by adding ethylene oxide, proprene oxide and the like to the bisphenol. Each of these may be used alone, or two or more types may be used in combination.

The above (b) is used as an electron conductive agent in the surface layer of the charging roll. As described in (b), those having a specific surface area within a specific range can be preferably used. The specific surface area of (b) is preferably in the range of 40 to 300 m2 / g. More preferably 42-240 m
It is within the range of 2 / g.
By the range of the specific surface area of (b) above, the electric resistance value of the surface layer of the charging roll can be made more uniform.
The specific surface area of (b) can be measured by the nitrogen adsorption method (JIS K 6217-2).

The carbon black of (b) is preferably having a surface functional group. Examples of such a surface functional group include a carboxylate group (-COO-) and a hydroxyl group (-OH). When the (b) has a surface functional group, the dispersion stability of the (b) on the surface layer of the charging roll 10 is excellent.

The above (c) is used as particles for forming surface roughness in the surface layer of a charged roll.
The above (c) may be either an inorganic particle or an organic particle as long as it has at least a large number of pores on the particle surface.
As described in (c), those having an oil absorption amount and a pore size within a specific range can be preferably used. The oil absorption amount of (c) is preferably 200 to 500 ml / 100 g, and the pore size is preferably in the range of 5 to 20 nm.
As a result, the binder polymer (a) forming the surface layer penetrates into the porous particles, and the adhesion between the binder polymer on the surface layer and the porous particles is improved. In particular, when relatively large porous particles having an average particle diameter of 5 μm or more are used, it is possible to prevent the porous particles from falling off from the surface layer during durability.
When the oil absorption of the porous particles is less than 200 ml / 100 g, the amount of the binder polymer that penetrates into the porous particles is small, and the adhesion between the binder polymer and the porous particles becomes insufficient.
Porous particles tend to fall off from the surface layer during durability.
From this viewpoint, the oil absorption of the porous particles is more preferably 250 ml / 100 g or more, still more preferably 300 ml / 100 g or more.
On the other hand, when the oil absorption amount of the porous particles is larger than 500 ml / 100 g, the particles are likely to aggregate, the dispersibility is lowered, and the uniformity of the surface unevenness is lowered.
If the pore size of the porous particles is less than 5 nm, it is difficult for the binder polymer to enter the inside thereof, the adhesion between the binder polymer and the porous particles becomes insufficient, and the porous particles tend to fall off from the surface layer during durability. From this viewpoint, the pore size of the porous particles is 5 nm or more, more preferably 7 nm or more, still more preferably 8 nm or more. On the other hand, when the pore size of the porous particles is more than 20 nm, the porous particles are likely to aggregate, the dispersibility is lowered, and the uniformity of the surface unevenness is lowered. From this point of view, the pore size of the porous particles is 20 nm or less.
It is more preferably 17 nm or less, still more preferably 15 nm or less. The oil absorption of the porous particles is measured by JIS K5101-13-2 <Pigment Test Method-Part 13: Oil Absorption-Section 2: Boiled Flax Oil Method>. The pore size of the porous particles is determined by the BJH method (JIS 8831-2).
).

Specific examples of the (c) porous particles include silica particles, (meth) acrylic resin particles, and polyamide resin particles having a large number of pores.
These can be used alone or in combination of two or more. Of these, silica particles are preferable from the viewpoints of adhesion between the elastic layer and the surface layer, processability, cost, and the like.

When the porous particles (c) have a surface functional group, they are excellent in dispersibility. Then, such a binder polymer easily enters the inside of the porous particles, and the adhesion between the binder polymer and the porous particles is improved. Further, when the binder polymer is water-soluble, water-dispersible, or soluble in a water / alcohol mixed solvent, the porous particles are preferably hydrophilic. Among them, the porous particles are preferably porous silica particles having a silanol group on the particle surface. The silanol groups on the surface of the porous particles improve hydrophilicity. Hydrophilic porous silica particles have many silanol groups on the surface. On the other hand, when the binder polymer is lipophilic solvent soluble, the porous particles are preferably lipophilic. Among them, the lipophilic porous particles are preferably porous silica particles in which the silanol group on the surface is modified (surface treated) with another lipophilic modifying group (ODS, silicone, etc.). Examples of the hydrophilic porous silica particles include those having a silanol group of 4000 μmol / g or more. On the other hand, as the lipophilic porous silica particles, the lipophilic modifying group is 4000 μmol / g.
Those having the above can be mentioned.
The amount of silanol group and other lipophilic modifying group is determined by a simple ignition loss method (JIS K1).
It can be measured in 150).

Since (d) is an acrylic modifier, it has a hydrocarbon chain portion due to a (meth) acryloyl group.
Since the hydrocarbon chain portion due to the (meth) acryloyl group is attracted to the hydrocarbon chain due to the polyester portion of (a) by interaction, it is immobilized on the surface layer.
The bleed-out of (d) is suppressed. Then, at least one selected from the silicone group and the fluorine-containing group of (d) is oriented to the polar surface of the surface layer because it does not attract due to the interaction with the hydrocarbon chain caused by the polyester portion of (a). .. Silicone groups and fluorine-containing groups oriented on the extreme surface of the surface layer have a low affinity for components derived from untransferred toner and toner, so they can exert the effect of preventing adhesion of components derived from untransferred toner and toner. it can. Further, in the above (d), functions such as slipperiness and chargeability can be imparted to the surface of the surface layer by the silicone group or the fluorine-containing group oriented on the polar surface of the surface layer. The above (d) may have a cationic group or may not have a cationic group.

The silicone group (d) is a silicone group from the viewpoints of excellent surface orientation of a silicone group or a fluorine-containing group and an excellent compatibility effect of a hydrocarbon chain portion due to a (meth) acryloyl group with the above (a). An acrylic copolymer comprising a polymer segment having at least one selected from the fluorine-containing group and a polymer segment having no silicone group and a fluorine-containing group is preferable. Of these, acrylic block copolymers are preferable.
A polymer segment having at least one selected from a silicone group and a fluorine-containing group can be formed, for example, from a compound having at least one selected from a silicone group and a fluorine-containing group and another polymer. .. Polymer segments that do not have silicone and fluorine-containing groups can be formed from other polymers.

The acrylic modifier represents a polymer of (meth) acrylate, a polymer of (meth) acrylamide, a copolymer of (meth) acrylate and (meth) acrylamide, and the like. (Meta) acrylate is a general term for acrylate and methacrylate. Further, (meth) acrylamide is a general term for acrylamide and metaacrylamide. Further, the (meth) acryloyl group is a general term for an acryloyl group and a methacryloyl group.

Examples of (d) include (d1) an acrylic modifier having a silicone group, (d2) an acrylic modifier having a fluorine-containing group, and (d3) an acrylic modifier having a silicone group and a fluorine-containing group. Agents can be mentioned. These may be used alone as the above-mentioned (d), or may be used alone.
Two or more types may be used in combination.

The above (d1) can be obtained by polymerizing a (meth) acrylate having a silicone group and / or a (meth) acrylamide having a silicone group. The above (d
1) may be a copolymer containing one or more non-modified (meth) acrylates or non-modified (meth) acrylamides as a copolymerization component. When a non-modified (meth) acrylate or a non-modified (meth) acrylamide is contained as a copolymerization component, there is an advantage in terms of compatibility with the above (a) and the like.

The (d1) silicone group-bearing (meth) acrylate and / or silicone group-bearing (meth) acrylamide is an organopolysiloxane having one or more (meth) acryloyl groups and / or acrylamide groups. This organopolysiloxane has an organic group in addition to the (meth) acryloyl group. The organic group is a monovalent or unsubstituted hydrocarbon group. The unsubstituted hydrocarbon group includes an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group and a dodecyl group, an aryl group such as a phenyl group, a β-phenylethyl group and a β-phenylpropyl group. Aralkill group of. Examples of the substituted hydrocarbon group include a chloromethyl group, a 3,3,3-trifluoropropyl group and the like. As the organopolysiloxane, those having a methyl group as an organic group are generally often used because of ease of synthesis and the like.
The organopolysiloxane is preferably linear, but may be branched or cyclic. The molecular weight of the organopolysiloxane is not particularly limited, but those having a number average molecular weight in the range of 200 to 30,000 can be preferably used.

In the above (d1), examples of the copolymerizable non-modified (meth) acrylate include alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate.
As the alkyl (meth) acrylate, methyl (meth) acrylate and ethyl (meth)
Examples thereof include acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Hydroxyalkyl (meth) acrylates include hydroxyethyl (meth) acrylate and hydroxypropyl (meth).
Examples thereof include acrylate and hydroxybutyl (meth) acrylate. Of these, methyl (meth) acrylate is preferable from the viewpoint of copolymerization reactivity and the like.

Examples of the copolymerizable non-denatured (meth) acrylamide in (d1) include (meth) acrylamide, alkyl (meth) acrylamide, and hydroxyalkyl (meth) acrylamide. Examples of alkyl (meth) acrylamide include methyl (meth) acrylamide, ethyl (meth) acrylamide, propyl (meth) acrylamide, butyl (meth) acrylamide, and 2-ethylhexyl (meth) acrylamide. Hydroxyalkyl (meth) acrylamide includes hydroxyethyl (meth) acrylamide, hydroxypropyl (meth) acrylamide, and hydroxybutyl (hydroxybutyl (meth) acrylamide).
Meta) Acrylamide and the like. Of these, methyl (meth) acrylamide is preferable from the viewpoint of copolymerization reactivity and the like.

The above (d2) can be obtained by polymerizing a (meth) acrylate having a fluorine-containing group and / or a (meth) acrylamide having a fluorine-containing group. The above (d
2) is a copolymer containing one or more non-modified (meth) acrylate or non-modified (meth) acrylamide as a copolymerization component, which does not have a silicone group or a fluorine group in addition to the above components. You may.

In (meth) acrylate having a fluorine-containing group and / or (meth) acrylamide having a fluorine-containing group, examples of the fluorine-containing group include fluoroalkyl groups having 1 to 20 carbon atoms. The fluoroalkyl group may be a perfluoroalkyl group in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms, or a fluoroalkyl group in which some hydrogen atoms of the alkyl group are substituted with fluorine atoms. You may. Of these, a perfluoroalkyl group is preferable from the viewpoint of being easily unevenly distributed on the surface of the surface layer.

Examples of the fluoroalkyl group having 1 to 20 carbon atoms include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, a trifluoroethyl group, a pentafluoropropyl group and a heptafluorobutyl group. ..

式（１）中、ＡはＯまたはＮＨであり、Ｒ１は水素またはメチル基であり、Ｒ２は炭素数
１〜２０のフルオロアルキル基である。 The (meth) acrylate having a fluorine-containing group and / or the (meth) acrylamide having a fluorine-containing group can be represented by, for example, the following general formula (1).

In formula (1), A is O or NH, R1 is a hydrogen or methyl group, and R2 is a fluoroalkyl group having 1 to 20 carbon atoms.

The above (d3) includes (meth) acrylate having a silicone group and / or (meth) acrylamide having a silicone group, and (meth) acrylate having a fluorine-containing group and / or (meth) acrylamide having a fluorine-containing group. Can be obtained by copolymerizing. In addition to the above components, the above (d3) further contains one or more non-modified (meth) acrylate or non-modified (meth) acrylamide as a copolymerization component, which does not have a silicone group or a fluorine group. It may be coalesced.

Examples of the (meth) acrylate having a silicone group and / or the (meth) acrylamide having a silicone group include those exemplified in the above (d1). Examples of the (meth) acrylate having a fluorine-containing group and / or the (meth) acrylamide having a fluorine-containing group can be mentioned as exemplified in the above (d2).

The content of (b) is not particularly limited, but is 10 to 50 with respect to 100 parts by mass of (a).
It is preferably within the range of parts by mass. As a result, the electric resistance value of the surface layer of the charging roll can be made uniform, and the overcharging phenomenon of the photosensitive drum can be suppressed.
From this point of view, the content of (b) is more preferably 20 parts by mass or more, still more preferably 25 parts by mass or more. Further, more preferably 40 parts by mass or less, still more preferably 3
It is 5 parts by mass or less.

The content of (c) is preferably in the range of 5 to 20 parts by mass with respect to 100 parts by mass of (a). This is because uniform unevenness can be formed on the surface layer of the charging roll, and the overcharging phenomenon of the photosensitive drum can be suppressed.
From this point of view, the content of (c) is more preferably 8 parts by mass or more, still more preferably 1
2 parts by mass or more. Further, it is more preferably 18 parts by mass or less, still more preferably 15 parts by mass or less.

Of the above (d), the content of the acrylic modifier (d1) having a silicone group is based on 100 parts by mass of the above (a) from the viewpoint of preventing adhesion of untransferred toner and components derived from the toner. It is preferably 0.1 part by mass or more. It is more preferably 0.5 parts by mass or more, and further preferably 1.0 part by mass or more. On the other hand, from the viewpoint of being more excellent in charge controllability, it is preferably 40 parts by mass or less with respect to 100 parts by mass of (a). More preferably 30
It is not more than parts by mass, more preferably 20 parts by mass or less.

Further, among the above (d), the content of the acrylic modifier (d2) having a fluorine-containing group is 100 parts by mass of the above (a) from the viewpoint of preventing adhesion of untransferred toner and components derived from the toner. On the other hand, it is preferably 0.1 part by mass or more. It is more preferably 0.5 parts by mass or more, and further preferably 1.0 part by mass or more. On the other hand, from the viewpoint of being more excellent in charge controllability, it is preferably 40 parts by mass or less with respect to 100 parts by mass of (a). It is more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less.

Further, among the above (d), the content of the acrylic modifier (d3) having a silicone group and a fluorine-containing group is the above-mentioned (a) from the viewpoint of preventing adhesion of untransferred toner and components derived from the toner. It is preferably 0.1 part by mass or more with respect to 100 parts by mass. It is more preferably 0.5 parts by mass or more, and further preferably 1.0 part by mass or more. On the other hand, from the viewpoint of being more excellent in charge controllability, it is preferably 40 parts by mass or less with respect to 100 parts by mass of (a). It is more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less.

The surface layer may or may not contain other binder polymer components in addition to the above (a). Other binder polymer components that may be included include urethane resin, nylon resin, acrylic resin, fluororesin, acrylic-fluororesin, polyether resin, polyester resin, polyolefin resin, polystyrene resin, vinyl chloride resin, vinyl acetate resin, and ethylene. -Vinyl acetate resin, polyimide resin, hydrin rubber (ECO), nitrile rubber (NBR), urethane rubber (U), acrylic rubber (
ACM), chloroprene rubber (CR), epoxidized natural rubber (ENR), isoprene rubber (IR), natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (B)
R) Ethylene-propylene-diene rubber (EPDM) and the like can be mentioned. The other binder polymer components may be thermoplastic or thermosetting.

In addition to the above (a) to (d), the surface layer may contain an additive, if necessary, as long as it does not interfere with the present invention. Additives include conductive agents, surface modifiers, roughness forming particles, lubricants, cross-linking agents, vulcanization accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, etc.
Examples include plasticizers, foaming agents, fillers, dispersants, defoamers, pigments, mold release agents and the like.

Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent other than the above (b).

Examples of the electronic conductive agent include graphite other than the above (b), conductive oxides such as conductive titanium oxide, conductive zinc oxide, and conductive tin oxide.

Examples of the ionic conductive agent include a quaternary ammonium salt, a quaternary phosphonium salt, a borate, and a surfactant. Although not particularly limited, these may be used alone as the ionic conductive agent, or may be used in combination of two or more. Of these, quaternary ammonium salts are preferred.

The surface layer can be formed by applying and drying the composition for forming the surface layer on the outer peripheral surface of the elastic body layer. The surface layer forming composition contains at least the above (a) to (d), and if necessary, contains other polymer components, additives, and solvents. As a solvent, MEK (methyl ethyl ketone)
, MIBK (methyl isobutyl ketone), acetone, toluene, xylene, methanol,
Ethanol, IPA (isopropyl alcohol), n-butanol, t-butanol, ethyl acetate, butyl acetate, NMP (n-methyl-2-pyrrolidone), DMF (dimethylformamide), DMAc (dimethylacetamide), n-hexane, cyclohexane , Isohexane, n-decane, isopentan, tetrahydrofuran, ethylene glycol monoacetamide, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, water and the like.

The thickness of the surface layer is not particularly limited, but is preferably in the range of 1.0 to 20 μm, more preferably in the range of 3.0 to 15 μm. The volume resistivity of the surface layer is not particularly limited, but is preferably 104 to 109 Ω · cm, more preferably 105 to 108.
It is in the range of Ω · cm, more preferably 106 to 107 Ω · cm.

The elastic layer contains a base rubber (polymer component). As a result, the layer has rubber elasticity. The elastic layer is formed of a conductive rubber composition containing a base rubber. The base rubber is obtained by cross-linking an uncross-linked rubber. The uncrosslinked rubber may be polar rubber or non-polar rubber.

The polar rubber is a rubber having a polar group, and examples of the polar group include a chloro group, a nitrile group, a carboxyl group, and an epoxy group. Specifically, as polar rubber,
Hydrin rubber, nitrile rubber (NBR), urethane rubber (U), acrylic rubber (ACM)
, Chloroprene rubber (CR), epoxidized natural rubber (ENR) and the like. Among the polar rubbers, hydrin rubber and nitrile rubber (NBR) are more preferable from the viewpoint that the volume resistivity tends to be particularly low.

Hydrin rubber includes epichlorohydrin homopolymer (CO), epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-allyl glycidyl ether binary copolymer (GCO), and epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary. Copolymers (GECO) and the like can be mentioned.

Examples of the urethane rubber include a polyether type urethane rubber having an ether bond in the molecule. The polyether type urethane rubber can be produced by reacting a polyether having hydroxyl groups at both ends with a diisocyanate. The polyether is not particularly limited, and examples thereof include polyethylene glycol and polypropylene glycol. The diisocyanate is not particularly limited, and examples thereof include tolylene diisocyanate and diphenylmethane diisocyanate.

Non-polar rubbers include isoprene rubber (IR), natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), butyl rubber (IIR), ethylene-propylene rubber (EPM), and ethylene-propylene-diene rubber (EPDM). ) And so on.

Examples of the cross-linking agent include a sulfur cross-linking agent, a peroxide cross-linking agent, and a dechlorination cross-linking agent.
These cross-linking agents may be used alone or in combination of two or more.

Examples of the sulfur cross-linking agent include conventionally known sulfur cross-linking agents such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, sulfur chloride, thiuram-based sulfide accelerator, and high molecular weight polysulfide. it can.

Examples of the peroxide cross-linking agent include conventionally known peroxide cross-linking agents such as peroxyketal, dialkyl peroxide, peroxyester, ketone peroxide, peroxydicarbonate, diacyl peroxide, and hydroperoxide. Can be done.

Examples of the dechlorination cross-linking agent include dithiocarbonate compounds. More specifically, quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-
Dithiocarbonate, 6-isopropylquinoxaline-2,3-dithiocarbonate, 5
, 8-Dimethylquinoxaline-2,3-dithiocarbonate and the like.

The amount of the cross-linking agent to be blended is preferably in the range of 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the uncrosslinked rubber from the viewpoint of being difficult to bleed. It is within the range, more preferably within the range of 1.0 to 7.0 parts by mass.

When a dechlorination cross-linking agent is used as the cross-linking agent, a dechlorination cross-linking accelerator may be used in combination. Examples of the dechlorination cross-linking accelerator include 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter abbreviated as DBU) or a weak acid salt thereof. The dechlorination cross-linking accelerator may be used in the form of DBU, but it is preferably used in the form of its weak acid salt from the viewpoint of its handling. Weak salts of DBU include carbonate, stearate, 2-ethylhexylate, benzoate, salicylate, 3-hydroxy-2-naphthoate, phenolic resin salt, 2-mercaptobenzothiazole salt, 2- Examples thereof include mercaptobenzimidazole salt.

Regarding the content of the dechlorination cross-linking accelerator, from the viewpoint of being difficult to bleed, the uncross-linked rubber 1
It is preferably in the range of 0.1 to 2 parts by mass with respect to 00 parts by mass. It is more preferably in the range of 0.3 to 1.8 parts by mass, and further preferably in the range of 0.5 to 1.5 parts by mass.

The elastic layer may contain a conductive agent such as an ionic conductive agent or an electronic conductive agent. As the ionic conductive agent and the electronic conductive agent, those listed on the surface layer can be preferably used.

Various additives may be appropriately added to the elastic layer, if necessary. Additives include lubricants, vulcanization accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, foaming agents, fillers, dispersants, defoamers, pigments, and release agents. Molds and the like can be mentioned.

The elastic layer can be adjusted to a predetermined volume resistivity depending on the type of base rubber, the amount of the ionic conductive agent, the amount of the electronic conductive agent, and the like. The volume resistivity of the elastic layer may be appropriately set in the range of 102 to 10 Ω · cm, 103 to 109 Ω · cm, 104 to 108 Ω · cm, etc., depending on the intended use.

The thickness of the elastic layer is not particularly limited, and is 0.1 to 10 mm depending on the application and the like.
It may be set appropriately within the range of. The elastic layer may be a foam or a non-foam.

The elastic layer can be produced, for example, as follows. First, the shaft body is coaxially installed in the hollow portion of the roll molding die, an uncrosslinked conductive rubber composition is injected, heated and cured (crosslinked), and then demolded or the shaft is removed. An elastic body layer is formed on the outer periphery of the shaft body by extrusion molding an uncrosslinked conductive rubber composition on the surface of the body.

The shaft body is not particularly limited as long as it has conductivity. Specifically, a metal core such as iron, stainless steel, and aluminum, a core metal made of a hollow body, and the like can be exemplified. If necessary, an adhesive, a primer, or the like may be applied to the surface of the shaft body. In other words
The elastic body layer may be adhered to the shaft body via an adhesive layer (primer layer). adhesive,
If necessary, the primer or the like may be conductive.

According to the charged roll having the above configuration, at least the surface layer is selected from (a) amorphous polyester-based binder polymer, (b) carbon black, (c) porous particles, (d) silicone group and fluorine-containing group. Since it contains one type of acrylic modifier, it suppresses the adhesion of untransferred toner and toner-derived components to the charging roll, and even if there is adhesion, the effect of adhesion is minimized, and it has not been done. The overcharge phenomenon of the photosensitive drum due to the charge of the transfer toner and the components derived from the toner is suppressed. As a result of including the above (a) to (d), the adhesion of untransferred toner and components derived from the toner is suppressed on the surface of the charged roll, and even if there is adhesion, its influence is minimized. It is presumed that this is because the influence of the untransferred toner and the electric charge of the component derived from the toner is suppressed. An excellent effect can be obtained by the combination of the above (a) to (d). If all the components (a) to (d) above are not included, the above-mentioned excellent effect cannot be obtained. For example, the surface layer does not contain the above (a), but instead of the above (a), contains a crystalline polyester-based binder polymer, and the crystalline polyester-based binder polymer and the above (b) to (d).
) Only, the untransferred toner and the components derived from the toner adhere to the surface layer of the charging roll, and the influence of the electric charge of the deposit cannot be suppressed, so that the above-mentioned excellent effect cannot be obtained.

The configuration of the charging roll according to the present invention is not limited to the configuration shown in FIG.
For example, in the charging roll shown in FIG. 1, another elastic body layer may be provided between the shaft body and the elastic body layer. In this case, the other elastic layer is the base layer of the charging roll,
The elastic layer functions as a resistance adjusting layer for adjusting the resistance of the charging roll. The other elastic layer can be composed of, for example, any of the materials listed as the materials constituting the elastic layer. Further, for example, in the charging roll shown in FIG. 1, another elastic body layer may be provided between the elastic body layer and the surface layer. In this case, the elastic layer is the base layer of the charging roll, and the other elastic layer functions as a resistance adjusting layer for adjusting the resistance of the charging roll.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

(Examples 1 to 7)
<Preparation of conductive rubber composition>
With respect to 100 parts by mass of isoprene rubber, 30 parts by mass of carbon black, 6 parts by mass of zinc oxide, 2 parts by mass of stearic acid, 1 part by mass of sulfur, 0.5 parts by mass of thiazole-based vulcanization accelerator, 0 parts by mass of tyraum-based vulcanization accelerator. A conductive rubber composition was prepared by blending 5 parts by mass and 50 parts by mass of heavy calcium carbonate and kneading for 10 minutes using a closed mixer whose temperature was adjusted to 50 ° C.

The following materials were prepared as materials for the conductive rubber composition.
-Rubber component isoprene rubber (IR) [manufactured by JSR Corporation, "JSR IR2200"]
-Conducting agent Carbon black (electronic conductive agent) [Manufactured by Cabot Japan Co., Ltd., "Show Black N"
762 "]
・ Zinc oxide [manufactured by Sakai Chemical Industry Co., Ltd., "2 types of zinc oxide"]
・ Stearic acid [NOF CORPORATION, "Stearic acid Sakura"]
・ Sulfur ["Powdered sulfur" manufactured by Tsurumi Chemical Industry Co., Ltd.]
-Vulcanization accelerator Thiazole-based vulcanization accelerator [manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., "Noxeller DM"]
Thiram-based vulcanization accelerator [manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., "Noxeller TRA"]
-Inorganic filler particles Heavy calcium carbonate [manufactured by Shiraishi Calcium Co., Ltd., "Whiten B", average particle size 3.6μ
m]

<Preparation of elastic layer>
The prepared conductive rubber composition was extruded into a crown shape on the outer circumference of a core metal having a diameter of 6 mm and made of free-cutting steel (SUM) using an extrusion molding device. Specifically, by supplying the conductive rubber composition to the gap between the die and the core metal while passing the core metal through the circular mouth portion of the die of the extrusion molding apparatus, the outer circumference of the core metal is elastic. The body layer was extruded. During this extrusion molding, the shape of the elastic layer precursor was made into a crown shape by changing the passing speed of the core metal and controlling the amount of the conductive rubber composition adhered to the core metal in the longitudinal direction. Then, this was heat-treated at 180 ° C. for 30 minutes. As a result, a predetermined elastic body layer (thickness 1.5 mm) was formed on the outer circumference of the core metal.

<Preparation of surface layer>
Amorphous polyester-based binder polymer, carbon black, porous particles, surface modifier having a silicone group or surface modifier having a fluorine group are blended so as to have the blending amount (part by mass) shown in Table 1. Then, 200 parts by mass of methyl ethyl ketone (MEK) was added, and the mixture was mixed and stirred by applying ultrasonic waves for a predetermined time to prepare a liquid composition for forming a surface layer. Next, this liquid composition was roll-coated on the outer peripheral surface of the elastic body layer and heat-treated to form a surface layer (thickness 10 μm) on the outer peripheral surface of the elastic body layer. As a result, a charged roll was produced.

(Comparative Example 1)
In the preparation of the surface layer, a charged roll was prepared in the same manner as in Example 2 except that a crystalline polyester-based binder polymer was blended in place of the amorphous polyester-based binder polymer.

(Comparative Example 2)
In the preparation of the surface layer, a charged roll was prepared in the same manner as in Example 2 except that carbon black was not blended.

(Comparative Example 3)
In the preparation of the surface layer, a charged roll was prepared in the same manner as in Example 2 except that the porous silica particles were not blended.

(Comparative Example 4)
In the preparation of the surface layer, a charged roll was prepared in the same manner as in Example 2 except that a surface modifier having a silicone group was not blended.

The materials used as the surface layer material are as follows.
Amorphous polyester binder polymer <1>: Toyobo "Byron 220" (number average molecular weight 3000, Tg: 53 ° C)
Amorphous polyester binder polymer <2>: Toyobo "Byron 226" (number average molecular weight 8000, Tg: 65 ° C)
Amorphous polyester binder polymer <3>: Toyobo "Byron 237" (number average molecular weight 15000, Tg: 70 ° C)
Amorphous polyester binder polymer <4>: Toyobo "Byron 885" (number average molecular weight 8000, Tg: 79 ° C)
Amorphous polyester binder polymer <5>: Toyobo "Byron 637" (number average molecular weight 29000, Tg: 21 ° C)
Crystalline polyester binder polymer <1>: Toyobo "GM-415" (number average molecular weight 10000, Tg: -8 ° C)
-Carbon black <1>: Lion's "Ketchen EC300J"
-Porous particles <1>: Silica "Sunsphere H-121 (particle size 1)" manufactured by AGC SI Tech
2 μm) ”
-Porous particles <2>: "Nylon 6TR-1 (particle size 13 μm)" manufactured by Toray Industries, Inc.
-Surface modifier having a silicone group: Acrylic polymer having a silicone group "NOF" Modiper FS710-1 ""
-Fluorine group-containing surface modifier: Acrylic polymer having a fluorine-containing group "NOF" Modiper F206 ""

For each of the produced charged rolls, the adhesion of toner and components derived from the toner was evaluated. In addition, the amount of charge was measured. In addition, image evaluation was performed. The evaluation results and the compounding composition of the surface layer forming composition are shown in Table 1 below.

(Toner and components derived from toner adhere)
Assemble the manufactured charging roll to the cartridge from which the cleaning blade has been removed, and attach the cartridge to the actual machine (HP "CLJ4525dn") at 32.5 ° C x 85%.
It was confirmed that the toner and the components derived from the toner adhered to the charged roll after the image was drawn in the high temperature and high humidity environment of RH. Using a laser microscope (“VK-8710” manufactured by KEYENCE CORPORATION), surface observation was performed with a lens having a magnification of 50 times, and the amount of toner and toner-derived component adhered to the image was calculated by an analysis application. In terms of area ratio, the adhesion amount of 5% or less of the components derived from toner or toner is particularly difficult to adhere "◎", the adhesion amount of components derived from toner or toner is more than 5% and 10% or less is difficult to adhere "○", toner or toner 10% adhesion of components derived from
It was marked as "x", which is easy for super to adhere.

(Measurement of charge amount)
As shown in FIG. 3, the photosensitive drum 1 of the HP "CLJ4525dn" cartridge is assembled to the rotating jig 6, and each charging roll 2 is brought into contact with the rotating jig 6, and a load of 1 kg is applied to both ends of the charging roll 2. did. At this time, the whole was surrounded by a box to block light. Only a DC voltage of −1.0 KV was applied from the high-voltage power supply 3 connected to the charging roll 2, and the drum potential after rotating the photosensitive drum 1 once was measured by a surface electrometer 5 equipped with a high-voltage probe 4. ..

(Difference in charge amount)
By blocking the electrodes and printing a white background, toner fog was intentionally caused on the surface of the charged roll. After that, the charge amount was measured in the same manner as the charge amount measurement described above. The difference from the value of the charge amount at the time of toner fog was calculated based on the value of the charge amount when there was no toner fog. When the charge difference is 3 V or less, the effect of overcharging is particularly small "◎", when the charge difference is 8 V or less, the effect of overcharge is small "○", and when the charge difference is more than 8 V, the effect of overcharge is large "x". ..

(Image evaluation)
Assemble the manufactured charging roll to the cartridge from which the cleaning blade has been removed, attach the cartridge (black) to the actual machine (HP "CLJ4525dn"), and set the temperature at 15 ° C.
Imaging was performed in a 25% density halftone under a 10% RH environment. Those with no unevenness in the image were evaluated as particularly good "◎", those with almost no unevenness in the image were evaluated as good "○", and those with many unevenness in the image were evaluated as defective "x".

From Examples and Comparative Examples, at least the surface layer of the charged roll is selected from (a) amorphous polyester binder polymer, (b) carbon black, (c) porous particles and (d) silicone and fluorine-containing groups. It can be seen that the inclusion of the acrylic modifier having one kind suppresses the adhesion of the untransferred toner and the components derived from the toner to the charged roll. Further, it can be seen that the difference in the amount of charge due to the charge of the untransferred toner and the components derived from the toner can be suppressed to a small extent. Then, it can be seen that the image becomes good.

By comparing Examples 1 to 3, the influence of (a) the number average molecular weight of the amorphous polyester binder polymer can be confirmed.
It can be seen that when the number average molecular weight is small, the difference in charge amount is excellent, and when the number average molecular weight is large, the toner and the adhesion of components derived from the toner are excellent.
By comparing Example 4 and Example 2, the influence of (a) Tg of the amorphous polyester binder polymer can be confirmed.
It can be seen that when Tg is low, the difference in charge amount and adhesion of components derived from toner or toner are excellent, and when Tg is high, adhesion of components derived from toner or toner is excellent.
By comparing Example 6 and Example 2, the influence of (d) an acrylic modifier having at least one selected from a silicone group and a fluorine-containing group can be confirmed.
It can be seen that the surface modifier having a silicone group is excellent in adhesion of toner and components derived from toner.
By comparing Example 7 and Example 2, the influence of (c) porous particles can be confirmed.
It can be seen that the porous silica particles are excellent in the difference in the amount of charge and the adhesion of the toner and the components derived from the toner.

Comparing Example 2 and Comparative Example 1, when the surface layer of the charged roll is (a) an amorphous polyester-based binder polymer, adhesion of untransferred toner or a component derived from the toner to the charged roll can be suppressed. I understand. The difference in the amount of charge due to the charge of the untransferred toner and the components derived from the toner can be suppressed to a small value. Further, comparing Example 2 and Comparative Example 2, the surface layer of the charged roll is (
b) When carbon black is contained, it can be seen that the difference in the amount of charge due to the charge of the untransferred toner or the component derived from the toner can be suppressed to a small value. Further, comparing Example 2 and Comparative Example 3, when (c) porous silica particles are contained in the surface layer of the charging roll, the difference in the amount of charge due to the charge of the untransferred toner or the component derived from the toner can be suppressed to be small. You can see that. And
Comparing Example 2 and Comparative Example 4, when the acrylic modifier having at least one selected from (d) a silicone group and a fluorine-containing group in the surface layer of the charging roll is contained, the charging roll is not yet charged. It can be seen that the adhesion of the transfer toner and the components derived from the toner is suppressed.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. ..

10 Charged roll 12 Axial body 14 Elastic body layer 16 Surface layer 18 Porous particles

Claims (4)

A shaft body, an elastic body layer formed on the outer periphery of the shaft body, and a surface layer formed on the outer periphery of the elastic body layer are provided, and the surface layer contains the following (a) to (d). A charging roll for electrophotographic equipment, which is formed from a composition.
(A) Amorphous polyester binder polymer (b) Carbon black (c) Porous particles (d) Acrylic modifier having at least one selected from silicone group and fluorine-containing group The charging roll for an electrophotographic apparatus according to claim 1, wherein the (a) has a number average molecular weight in the range of 1000 to 15000. Claim 1 or 2 according to (a) above, wherein Tg is in the range of 50 to 70 ° C.
The charging roll for electrophotographic equipment described in. The charging roll for an electrophotographic apparatus according to any one of claims 1 to 3, wherein the (c) is a porous silica particle.

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