JP2008299108A - Charging member, electrophotographic apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging member capable of stably charging a photoreceptor drum. <P>SOLUTION: Regarding the charging member having a conductive elastic layer on a conductive substrate, the surface roughness Rzjis of the conductive elastic layer in a longitudinal direction is 2.0 to 20.0 μm, and the charging member is characterized by satisfying the following relation (A): (A) (length of the charge part of the conductive elastic body)/(8 mm)=N(N is integer obtained by counting fractions as one, N≥3); then, the conductive elastic body part is divided into N areas, and the elastic bodies are expressed by 1 to N from one end in this order. The surface roughness Rzjis-ave.(1) and Rzjis-ave.(N) are in the range of 2.0 to 7.0 μm, and at least one or more points among Rzjis-ave.(2 to N-1) are 1.2 to 5.0 times the surface roughness Rzjis-ave.(1) and Rzjis-ave.(N). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a charging member (charging roller) used in an image forming apparatus using an electrophotographic process in office automation equipment such as LBP (Laser Beam Printer), copying machines, and facsimiles.

  With the recent increase in speed and durability of image forming apparatuses, charging members used in image forming apparatuses are also required to have high precision and high durability.

  The charging roller used in the image forming apparatus is the most common charging member, and performs charging processing in contact with the photosensitive drum. It has a conductive substrate, a conductive elastic layer (resistive layer) formed on the conductive substrate, and a surface layer formed on the conductive elastic layer, if desired. Then, using such a charging roller, a voltage is applied to the conductive substrate to cause a minute discharge in the vicinity of the contact nip between the charging roller and the photosensitive drum, thereby charging the surface of the photosensitive drum. Hereinafter, the conductive substrate is also referred to as a cored bar.

  When the image forming apparatus is subjected to an image endurance test using a halftone image using a charging roller as a charging member, the surface of the charging roller is maintained due to the durability of the image and the external additive attached to the toner. There is a problem of getting dirty. As a result, image defects such as white streaks, black streaks, and density unevenness occur starting from a heavily soiled portion on the surface of the charging roller. This is because the surface of the charging roller becomes dirty, and the photosensitive drum cannot be uniformly charged.

  As one of the causes for the surface of the charging member to become dirty, if the surface roughness of the charging member is rough, the toner and external additives attached to the toner are likely to enter the recesses on the surface, and the charging member is likely to become dirty. It is possible. Also, depending on the longitudinal shape of the charging member, when both ends are supported and contacted with the photosensitive drum, the longitudinal both ends on the surface of the charging member tend to become dirty in the image durability test, and the image due to poor charging at the image end It may become defective.

  In order to prevent charging failure due to contamination of the charging member, the surface shape (surface roughness) of the charging member is controlled (see, for example, Patent Document 1 and Patent Document 2), or the dynamic friction coefficient of the surface of the charging member. (For example, refer to Patent Document 3 and Patent Document 4), increasing the water repellency of the surface of the charging member (for example, refer to Patent Document 5), and the like. However, in the method for controlling the surface shape (surface roughness) of the charging member, it may not be possible to sufficiently remove the dirt on both ends of the charging member surface. Considering the demands for higher durability, simplified mechanism, smaller size, etc., we will further control the surface shape (surface roughness) of the charging member, especially the surface shape (surface roughness) in the longitudinal direction of the charging member. There is a need.

The surface shape (surface roughness) of the charging member is a very important characteristic for uniformly charging the surface of the photosensitive drum. In particular, when the surface roughness of the charging member is large, in addition to the minute discharge occurring in the vicinity of the contact nip with the photosensitive drum, the minute discharge also occurs in the contact nip, and the surface of the photosensitive drum is charged more uniformly. I think that. When the surface roughness of the charging member is small, there is a case where minute discharge is reduced in the vicinity of the contact nip with the photosensitive drum and in the contact nip, and the surface of the photosensitive drum may not be uniformly charged. Conceivable.
Japanese Patent Laid-Open No. 7-049605 JP-A-7-199593 JP-A-9-160355 JP-A-9-160354 JP 2000-019814 A

  An object of the present invention is to provide a charging member that prevents image defects by stably charging a photosensitive drum used in an image forming apparatus using an electrophotographic process.

  Another object of the present invention is to provide an image forming apparatus and a process cartridge having the charging member.

In the charging member having a conductive elastic layer on a conductive substrate, the surface roughness Rzjis in the longitudinal direction of the conductive elastic layer is 2.0 to 20.0 μm, and the following relationship (A) is satisfied. It is a charging member characterized by a certain feature.
(A) (the length of the charged portion of the conductive elastic body) / (8 mm) = N (N is an integer part rounded up after the decimal point, N ≧ 3). 1 to N. At this time, the surface roughness Rzjis-ave. (1) and Rzjis-ave. (N) is 2.0 to 7.0 μm, and Rzjis-ave. At least one point of (2-N-1) has a surface roughness Rzjis-ave. (1) and Rzjis-ave. It is 1.2 to 5.0 times (N).
(Surface roughness Rzjis is JIS94-B0601 ten-point average roughness)
(Surface roughness Rzjis-ave. Is an average value of six measurements in the circumferential direction)
The present invention also provides an image forming apparatus and a process cartridge having the charging member.

  According to the present invention, it is possible to provide a charging member that suppresses contamination on the surface of the charging member due to toner and an external additive attached to the toner, stably charges the photosensitive drum, and prevents image defects. it can.

  In addition, an image forming apparatus and a process cartridge having the charging member can be provided.

  Hereinafter, the present invention will be described in more detail with an example of a charged rubber roller.

  Examples of the molding method of the rubber roller in which the conductive rubber layer as the conductive elastic layer is provided on the core metal include an injection molding method, an extrusion molding method, a transfer molding method, and a press molding method. It is not limited to. For example, in the injection molding method, two cylindrical pieces are assembled, a shaft-shaped metal core is held concentrically in a cylindrical mold, and the rubber material is injected and heated to cure the rubber material and form a rubber roller. . In the extrusion molding method, after the rubber material is extruded into a tube shape, the core metal is covered with the tube-shaped rubber material, or the core metal and the rubber material are integrally extruded to form a cylindrical rubber roller. In view of shortening the manufacturing time, among these molding methods, an extrusion molding method in which a rubber material is extruded integrally with a core metal to mold a rubber roller is preferable.

  As for the method of vulcanizing by heating the rubber roller, any method such as a hot stove, vulcanizing can, hot platen, far / near infrared ray, induction heating, etc. may be used. A method of pressing the rubber roller while rotating it may be used in combination. The rubber roller is preferably heated at a temperature in the range of 140 ° C. or higher and 220 ° C. or lower for a time of 10 minutes to 120 minutes to vulcanize the rubber roller.

In addition, in order to obtain a desired roller shape and surface roughness, the above-described heated cylindrical or planar member is blasted according to the desired roller shape and surface roughness and used. A method of heating and vulcanizing a rubber roller, a dry roller method using a rotating grindstone to obtain a desired roller shape and surface roughness after heating and vulcanization,
There is also a method in which a rubber roller is injection molded using a mold whose inner surface is blasted according to a desired roller shape and surface roughness.

  The polishing means is not particularly limited, and there is a so-called traverse method in which a grindstone moves and polishes, and a plunge method in which lump polishing is performed without moving by a wider grindstone.

  In FIG. 1, the schematic diagram of an example of the rubber roller manufacturing method by an extrusion method is shown. The extruder 1 includes a crosshead 2. The extruder 1 integrally extrudes the metal core 4 sent to the crosshead 2 by the metal core feed roller 3 and the rubber material introduced into the extruder, thereby forming a rubber layer on the metal core 4. After the rubber layer is formed in a cylindrical shape around the core metal, the end portion is cut and removed 5 to form the rubber roller 6.

  FIG. 2 is a schematic diagram showing an example of a rubber roller manufacturing method using traverse polishing. The rubber roller 6 is attached to a rotatable member 7 such as a spindle, center, collet chuck or the like, and the grindstone 8 is disposed so as to contact the rubber roller. Then, while rotating the grindstone at a speed of about 1600 rpm, it is brought into contact with a rubber roller rotating at a speed of about 300 to 400 rpm, and moved from one end side to the other end side of the rubber roller to obtain a desired roller shape and surface roughness. Grind.

  The rubber roller is formed in a crown shape in which the outer diameters at both ends are smaller than the center portion in the longitudinal direction of the roller, and the crown amount is 70 μm or more and 160 μm or less, and particularly preferably 90 μm or more and 130 μm or less. If the crown amount is smaller than 70 μm, the central portion may float above the photosensitive drum if the central portion is larger than 160 μm, and charging cannot be performed uniformly.

  The crown amount of the rubber roller was defined as (crown amount) = D2− (D1 + D3) / 2. D1 (μm) is the outer diameter at one end in the longitudinal direction, D2 (μm) is the outer diameter at the center, and D3 (μm) is the outer diameter at the other end in the longitudinal direction, Both end portions D1 and D3 from the center portion D2 are positioned at 90 mm positions in the both end directions from the center portion.

As a method for imparting a surface roughness distribution in the longitudinal direction of the rubber roller of the present invention, the type of the grindstone (material, particle size, etc., for example, GC-120, 100, 80, 60, porosity) is selected, the polishing time, the rubber roller, A method of performing according to polishing conditions such as the direction of rotation and the number of rotations of the grinding wheel
A method of combining the materials of the grindstone so as to have a roughness distribution in the longitudinal direction of the grindstone according to the desired surface roughness distribution in the longitudinal direction of the rubber roller, or a method of imparting a particle size distribution to the grindstone,
When the rubber roller is heated and vulcanized, the heated cylindrical or flat member is subjected to blasting or the like according to the surface roughness distribution in the longitudinal direction of the desired rubber roller, and this is used to heat the rubber roller. There are a method of vulcanization and a method of injection molding of a rubber roller using a die whose inner surface is blasted in accordance with a desired surface roughness distribution in the longitudinal direction of the rubber roller.

  Also, the pressure distribution in the contact nip with the photosensitive drum may differ depending on the crown shape of the rubber roller. For example, the pressure in the contact nip of the rubber roller (charging member) with the photosensitive drum has a minimum value within the range of (N / 2) −3 to (N / 2) +3, which will be described later, and from the minimum value In some cases, the inclination increases with respect to R (1) and R (N). In that case, it is better to give the surface roughness distribution in the longitudinal direction of the rubber roller according to the pressure distribution in the contact nip. The surface roughness of the rubber roller is decreased at a portion where the pressure in the contact nip is large, and the surface roughness of the rubber roller is increased at a portion where the pressure is small.

  Here, an example of the method of providing the surface roughness distribution in the longitudinal direction of the rubber roller will be described with reference to an example of traverse polishing. The rubber roller is rotated so that the grindstone comes into contact with the rubber roller, is brought into contact with the rotating rubber roller while rotating the grindstone, and is moved from one end side to the other end side of the rubber roller. When the grindstone moves from one end side to the other end side of the rubber roller, the surface roughness distribution is given by changing the polishing time (gridstone feed rate) with which the grindstone is in contact with the rubber roller. For example, the surface roughness in the longitudinal direction of the rubber roller is reduced by slowing the feed speed of the grindstone on one end side in the longitudinal direction of the rubber roller, increasing the feed speed of the grindstone in the center, and slowing the feed speed of the grindstone on the other end side. The maximum value is obtained at the central portion, and the inclination is reduced from the central portion to both end portions.

  The core 4 of the rubber roller is preferably a stainless steel bar, a phosphor bronze bar, an aluminum bar, a heat-resistant resin bar or the like containing a steel material such as nickel-plated or chrome-plated SUM.

Further, the rubber layer provided on the core metal 4 has conductivity. As a rubber material for forming the rubber layer,
Examples thereof include natural rubber, butadiene rubber, hydrin rubber, styrene-butadiene rubber, nitrile rubber, ethylene-propylene rubber, butyl rubber, silicone rubber, urethane rubber, fluorine rubber, chlorine rubber, and thermoplastic elastomer. Any of these may be used. Conductive powders dispersed in rubber materials include carbons such as carbon black and conductive carbon, metal powders, conductive fibers, semiconductive metal oxide powders such as tin oxide, and mixtures thereof. Either of these is acceptable.

  The thickness of the conductive elastic layer (conductive rubber layer) is preferably 0.5 to 3.0 mm.

  Next, a method for forming the outermost surface layer of the rubber roller of the present invention will be described in detail.

  In general, the outermost surface layer is formed by applying a coating liquid for forming the outermost surface layer on the rubber layer of the rubber roller, and drying and curing. A coating method is not particularly limited, and a known method such as a dipping method, a spray method, a ring head coating method, or a roll coating method can be used. Any of these methods can be used in the present invention.

  Hereinafter, a method for forming the outermost surface layer will be described using the ring head coating method as an example. FIG. 3 shows a schematic diagram of an example of the ring head coating method. First, a ring head having a slit-like discharge port that is opened to the entire circumference at a distance that forms a predetermined interval with respect to the rubber roller 6 by supporting the rubber roller 6 obtained by the above-described method in a vertical state. (Ring head) 9 is arranged. The ring head 7 includes a slit-like discharge port 10, a liquid constricting portion 11, a liquid distribution chamber 13, and a liquid supply port 12 that are opened all around. The coating liquid is supplied from one or more liquid supply ports 12 provided in the ring head by a liquid supply means (for example, a syringe pump) outside the ring head 7. The coating liquid merges in the ring head 9 and passes through one or more liquid distribution chambers and one or more liquid constrictions for distributing in the circumferential direction. Reach 8 While relatively moving the rubber roller 6 and the ring head 9 at a predetermined speed (about 1 to 200 mm / s), the coating liquid is discharged from the entire circumference of the discharge port 10 to uniformly apply an appropriate amount of the coating liquid to the surface of the rubber roller. To do.

  The discharge amount onto the surface of the rubber roller is determined in consideration of the liquid viscosity and speed (relative movement speed between the rubber roller and the ring head) of the coating liquid used for forming the outermost surface layer, the composition of the coating liquid, the additive material, and the like. The opening width (slit width) of the slit-like discharge port opened on the entire circumference of the ring head is usually 0.05 mm or more, preferably 0.1 mm. As a material of the ring head, aluminum, a resin such as Teflon (registered trademark), or a steel material such as stainless steel is used, but it is preferable to use a steel material such as stainless steel having high processing accuracy.

  As the material for forming the outermost surface layer, silicone-based, fluorine-based, urethane-based, acrylic-based, urethane-modified acrylic-based, and silicone-modified urethane-based materials are used. In particular, a material containing polysiloxane having a fluorinated alkyl group and an oxyalkylene group is preferable.

  Further, the layer thickness of the outermost layer is preferably a thin film in view of the electrical characteristics or strength of the charging rubber roller, and is preferably 10 nm or more in terms of strength. Further, if the thickness of the outermost surface layer is too large, the outermost surface layer cannot follow the deformation of the rubber layer and is considered to hinder uniform charging, so 1000 nm or less is preferable.

  When the outermost surface layer is a very thin film as described above, the surface roughness of the rubber layer on the core metal and the surface roughness of the rubber roller provided with the outermost surface layer on the rubber layer are almost the same.

  Examples of the fluorinated alkyl group include those in which part or all of the hydrogen atoms of a linear or branched alkyl group are substituted with fluorine atoms. Among these, a linear perfluoroalkyl group having 6 to 31 carbon atoms is preferable.

  The oxyalkylene group is a divalent group (sometimes referred to as an “alkylene ether group”) having a structure represented by —O—R— (R: alkylene group). As this R (alkylene group), a C1-C6 alkylene group is preferable.

  The content of the fluorinated alkyl group in the polysiloxane is preferably 5.0 to 50.0 mass% with respect to the total mass of the polysiloxane. Moreover, it is preferable that content of the oxyalkylene group in the said polysiloxane is 5.0-70.0 mass% with respect to the total mass of polysiloxane. Content of the siloxane part (part which has a structure shown by -Si-O-Si-O -...) in polysiloxane is 20.0-90.0 mass% with respect to the total mass of polysiloxane. Preferably there is.

  The polysiloxane preferably further has an alkyl group and a phenyl group. The alkyl group is preferably a linear or branched alkyl group having 1 to 21 carbon atoms, and more preferably a methyl group, an ethyl group, an n-propyl group, a hexyl group or a decyl group.

When the polysiloxane further has an alkyl group and a phenyl group, the content of the fluorinated alkyl group, the oxyalkylene group, the alkyl group, the phenyl group, and the siloxane portion in the polysiloxane is as follows with respect to the total mass of the polysiloxane. It is preferable that it is the value of.
・ Fluorinated alkyl group: 5.0 to 50.0% by mass
・ Oxyalkylene group: 5.0 to 30.0% by mass
・ Alkyl group: 5.0 to 30.0% by mass
-Phenyl group: 5.0-30.0 mass%
Siloxane part: 20.0-80.0% by mass
The polysiloxane having a fluorinated alkyl group and an oxyalkylene group is preferably a polysiloxane obtained through the following steps (I) and (II).
(I) Condensation step of hydrolyzing and condensing a hydrolyzable silane compound having a cationically polymerizable group and a hydrolyzable silane compound having a fluorinated alkyl group (II) Cleaving the cationically polymerizable group Cross-linking step of cross-linking the hydrolyzable condensate obtained in step (I), as the hydrolyzable silane compound having a group capable of cationic polymerization, hydrolysis having a structure represented by the following formula (2) A functional silane compound is preferred.

(In the formula, R ²¹ represents a saturated or unsaturated monovalent hydrocarbon group. R ²² represents a saturated or unsaturated monovalent hydrocarbon group. Z ²¹ represents a divalent organic group. Rc ²¹ represents a group capable of cationic polymerization, d represents an integer of 0 to 2, e represents an integer of 1 to 3, and d + e = 3.)
The cationically polymerizable group represented by Rc ²¹ in the formula (2) means a cationically polymerizable organic group that generates an oxyalkylene group by cleavage, for example, a cyclic ether group such as an epoxy group or an oxetane group. And vinyl ether groups. Among these, an epoxy group is preferred from the viewpoint of availability and reaction control.

Examples of the saturated or unsaturated monovalent hydrocarbon group represented by R ²¹ and R ²² in the formula (2) include an alkyl group, an alkenyl group, and an aryl group. Among these, a C1-C3 linear or branched alkyl group is preferable, and a methyl group and an ethyl group are more preferable.

Examples of the divalent organic group represented by Z ²¹ in the formula (2) include an alkylene group and an arylene group. Among these, an alkylene group having 1 to 6 carbon atoms is preferable, and an ethylene group is more preferable.

E in the formula (2) is preferably 3. Also, in the aforesaid formula (2) d in 2, the two R ²¹ may be the same or may be different. Moreover, when e in the formula (2) is 2 or 3, two or three R ²² may be the same or different.

Below, the specific example of the hydrolysable silane compound which has a structure shown by the said Formula (2) is shown.
(2-1): Glycidoxypropyltrimethoxysilane (2-2): Glycidoxypropyltriethoxysilane (2-3): Epoxycyclohexylethyltrimethoxysilane (2-4): Epoxycyclohexylethyltriethoxysilane As the hydrolyzable silane compound having a fluorinated alkyl group, a hydrolyzable silane compound having a structure represented by the following formula (3) is suitable.

(In the formula, R ³¹ represents a saturated or unsaturated monovalent hydrocarbon group. R ³² represents a saturated or unsaturated monovalent hydrocarbon group. Z ³¹ represents a divalent organic group. Rf ³¹ represents a linear perfluoroalkyl group having 1 to ³¹ carbon atoms, f represents an integer of 0 to 2, g represents an integer of 1 to 3, and f + g = 3. .)
Examples of the saturated or unsaturated monovalent hydrocarbon group represented by R ³¹ and R ³² in the formula (3) include an alkyl group, an alkenyl group, and an aryl group. Among these, a C1-C3 linear or branched alkyl group is preferable, and a methyl group and an ethyl group are more preferable.

Examples of the divalent organic group represented by Z ³¹ in the formula (3) include an alkylene group and an arylene group. Among these, an alkylene group having 1 to 6 carbon atoms is preferable, and an ethylene group is more preferable.

The linear perfluoroalkyl group having 1 to ³¹ carbon atoms represented by Rf ³¹ in the formula (3) is particularly a linear perfluoroalkyl group having 6 to ³¹ carbon atoms from the viewpoint of processability. Is preferred.

G in the formula (3) is preferably 3. Furthermore, if f of the equation (3) is 2, the two R ³¹ may be the same or different. When g in the formula (3) is 2 or 3, two or three R ³² may be the same or different.

Below, the specific example of the hydrolysable silane compound which has a structure shown by the said Formula (3) is shown.
(3-1): CF ₃ — (CH ₂ ) ₂ —Si— (OR) ₃
(3-2): F (CF ₂ ) ₂ — (CH ₂ ) ₂ —Si— (OR) _{3
(3-3): F (CF 2} ) 4 - (CH 2) 2 -Si- (OR) 3
(3-4): F (CF ₂ ) ₆ — (CH ₂ ) ₂ —Si— (OR) ₃
(3-5): F (CF ₂ ) ₈ — (CH ₂ ) ₂ —Si— (OR) ₃
(3-6): F (CF ₂ ) ₁₀ — (CH ₂ ) ₂ —Si— (OR) ₃
(R in the formulas (3-1) to (3-6) represents a methyl group or an ethyl group.)
Among the compounds represented by the formulas (3-1) to (3-6), the compounds represented by the formulas (3-4) to (3-6) are preferable.

  Each of the hydrolyzable silane compound having a cationically polymerizable group and the hydrolyzable silane compound having a fluorinated alkyl group may be used alone or in combination of two or more.

When the hydrolyzable silane compound having the structure represented by the formula (3) is used as the hydrolyzable silane compound having a fluorinated alkyl group, the carbon number n _{A of} Rf ³¹ is 6 to ³¹ , and the carbon number n It is preferable to use a combination of two or more compounds having different _A from each other. When the hydrolyzable silane compound having the structure represented by the formula (3) is used in such a combination, the resulting polysiloxane has perfluoroalkyl groups having different carbon numbers. Perfluoroalkyl groups tend to be oriented toward the surface of the outermost surface layer. For this reason, if the polysiloxane contained in the outermost surface layer has perfluoroalkyl groups having different carbon numbers, the perfluoroalkyl groups having different lengths are oriented toward the surface of the outermost surface layer. . In this case, the fluorine atom concentration near the surface of the outermost surface layer is higher and the surface free energy of the outermost surface layer is higher than when a single length perfluoroalkyl group is oriented toward the surface of the outermost surface layer. Becomes lower. The outermost surface layer that reduces the surface free energy is effective in preventing contamination of the surface of the rubber roller by the toner and the external additive attached to the toner.

  When using two or more hydrolyzable silane compounds having the structure represented by the formula (3), select two or more compounds from the compounds represented by the formulas (3-4) to (3-6). Is preferred.

In the present invention, as described above, first, a hydrolyzable silane compound having a group capable of cationic polymerization in the condensation step (I) and a hydrolyzable silane compound having a fluorinated alkyl group are hydrolyzed and condensed. Thus, a hydrolyzable condensate is obtained. Then, the polysiloxane used in the charged rubber roller of the present invention can be obtained by cleaving the cationically polymerizable group in the crosslinking step (II) to crosslink the hydrolyzable condensate. From the viewpoint of controlling the surface characteristics of the charged rubber roller, it is preferable to further use a hydrolyzable silane compound having a structure represented by the following formula (1) in the condensation step (I) for obtaining a hydrolyzable condensate.
^{(R 11) a-Si- (} OR 12) b (1)
(Wherein R ¹¹ represents a phenyl group-substituted alkyl group or an unsubstituted alkyl group, or an alkyl group-substituted aryl group or an unsubstituted aryl group, and R ¹² represents a saturated or unsaturated monovalent group. A represents a hydrocarbon group, a represents an integer of 0 to 3, b represents an integer of 1 to 4, and a + b = 4.
The alkyl group of the phenyl group-substituted alkyl group or unsubstituted alkyl group represented by R ¹¹ in the formula (1) is preferably a linear alkyl group having 1 to 21 carbon atoms. In addition, as the aryl group of the alkyl group-substituted aryl group or unsubstituted aryl group represented by R ¹¹ in the formula (1), a phenyl group is preferable.

  A in the formula (1) is preferably an integer of 1 to 3, and more preferably 1. Further, b in the formula (1) is preferably an integer of 1 to 3, more preferably 3.

Examples of the saturated or unsaturated monovalent hydrocarbon group represented by R ¹² in the formula (1) include an alkyl group, an alkenyl group, and an aryl group. Among these, a linear or branched alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group, an ethyl group, and an n-propyl group are more preferable.

When a in the formula (1) is 2 or 3, two or three R ¹¹ may be the same or different. When b in formula (1) is 2, 3 or 4, two, three or four R ¹² may be the same or different.

Below, the specific example of the hydrolysable silane compound which has a structure shown by the said Formula (1) is shown.
(1-1): Tetramethoxysilane (1-2): Tetraethoxysilane (1-3): Tetrapropoxysilane (1-4): Methyltrimethoxysilane (1-5): Methyltriethoxysilane (1- 6): methyltripropoxysilane (1-7): ethyltrimethoxysilane (1-8): ethyltriethoxysilane (1-9): ethyltripropoxysilane (1-10): propyltrimethoxysilane (1- 11): propyltriethoxysilane (1-12): propyltripropoxysilane (1-13): hexyltrimethoxysilane (1-14): hexyltriethoxysilane (1-15): hexyltripropoxysilane (1- 16): Decyltrimethoxysilane (1-17): Decyltriethoxysilane (1-18): Decyltripro Xylsilane (1-19): Phenyltrimethoxysilane (1-20): Phenyltriethoxysilane (1-21): Phenyltripropoxysilane (1-22): Diphenyldimethoxysilane (1-23): Diphenyldiethoxysilane When the hydrolyzable silane compound having the structure represented by the formula (1) and the hydrolyzable silane compound having the structure represented by the formula (3) are used in combination, a in the formula (1) is 1 to 3 And b is preferably an integer of 1 to 3. Furthermore, it is preferable that one R ¹¹ out of a R ¹¹ is a linear alkyl group having 1 to 21 carbon atoms.

The number of carbon atoms of the linear alkyl group having ₁ to 21 carbon atoms is n ₁ (n ₁ is an integer of ₁ to 21), and the carbon number of Rf ³¹ in the formula (3) is n ₂ (n ₂ is 1). when set to an integer) of to 31, carbon number n ₁ of linear alkyl group of carbon number 1 to 21, preferably satisfies the following relationship.
n ₂ −1 ≦ n ₁ ≦ n ₂ +1
The linear alkyl group having 1 to 21 carbon atoms tends to be oriented toward the surface in the outermost surface layer of the charging rubber roller, like the perfluoroalkyl group. When the hydrolyzable silane compound represented by the formula (1) having a linear alkyl group satisfying the above relationship is used, the perfluoroalkyl group of the hydrolyzable silane compound having the structure represented by the formula (3) The effect by is preferable without being impaired.

The hydrolyzable silane compound having the structure represented by the formula (1) may be used alone or in combination of two or more. When using 2 or more types, it is preferable to use together that whose R < ¹¹ > in said Formula (1) is an alkyl group, and whose R < ¹¹ > in said Formula (1) is a phenyl group.

  Hereinafter, a specific method for producing the charged rubber roller of the present invention (a specific method for forming the outermost surface layer containing the polysiloxane) will be described.

  First, a hydrolyzable silane compound having a group capable of cationic polymerization, a hydrolyzable silane compound having a fluorinated alkyl group, and, if necessary, hydrolyzing the other hydrolyzable silane compound in the presence of water. Then, a hydrolyzable condensate is obtained by condensation. When hydrolyzing and condensing, a hydrolyzable condensate having a desired degree of condensation can be obtained by controlling temperature, pH and the like.

  Moreover, when hydrolyzing and condensing, metal alkoxide etc. may be utilized as a catalyst of a hydrolysis reaction, and a condensation degree may be controlled. Examples of the metal alkoxide include aluminum alkoxide, titanium alkoxide and zirconia alkoxide, and complexes thereof (acetylacetone complex and the like).

In addition, when obtaining the hydrolyzable condensate, the blending ratio of the hydrolyzable silane compound having a cationically polymerizable group and the hydrolyzable silane compound having a fluorinated alkyl group is such that the resulting polysiloxane has the following groups, etc. It is preferable to determine so as to include the following content.
・ Fluorinated alkyl group: 5.0 to 50.0% by mass relative to the total mass of polysiloxane
-Oxyalkylene group: 5.0 to 70.0% by mass relative to the total mass of polysiloxane
Siloxane part: 20.0-90.0% by mass with respect to the total mass of polysiloxane
Further, in addition to the hydrolyzable silane compound, when the hydrolyzable silane compound having the structure represented by the formula (1) is used, the resulting polysiloxane has the above-described group and the like in the above content. What is necessary is just to determine a mixture ratio so that it may be included.

  Specifically, the hydrolyzable silane compound having a fluorinated alkyl group is preferably blended so as to be in the range of 0.5 to 20.0 mol% with respect to the total hydrolyzable silane compound, and in particular, 1 It is more preferable to mix | blend so that it may become the range of 0.0-10.0 mol%.

When used in combination hydrolyzable silane compound having a structure represented by the formula (1), the structure represented amount of the hydrolyzable silane compound having a cationically polymerizable group and (M _C mol) in equation (1) The molar ratio (M _C : M ₁ ) of the blending amount (M ₁ mol) of the hydrolyzable silane compound is 10: 1 to 1:10
It is preferable to mix | blend so that it may become this range.

  Next, a coating solution for forming the outermost surface layer containing the obtained hydrolyzable condensate (sometimes referred to as the outermost layer coating solution) is prepared, applied onto the rubber layer of the rubber roller, and dried. . When the outermost surface layer coating liquid is applied on the rubber layer of the rubber roller, ring application using the ring head is preferred. Further, dip coating or a coating method using a roll coater may be used. In preparing the coating solution for the outermost surface layer, an appropriate solvent may be used in addition to the hydrolyzable condensate in order to improve coatability. Suitable solvents include, for example, alcohols such as ethanol and 2-butanol, ethyl acetate, methyl ethyl ketone, or a mixture thereof.

  Next, an active energy ray is irradiated to the coating solution for the outermost surface layer applied on the rubber layer of the rubber roller. The active energy ray may be an ultraviolet ray or an electron beam. Then, the cationically polymerizable group in the hydrolyzable condensate contained in the coating solution for the outermost surface layer is cleaved, whereby the hydrolyzable condensate can be crosslinked. The hydrolyzable condensate is cured by crosslinking to form the outermost surface layer. Moreover, you may heat-harden an outermost surface layer. In this case, any method such as a hot stove, a hot platen, far / near infrared rays, induction heating or the like may be used, or these heating methods may be used in combination.

  Here, when the outermost surface layer is irradiated with active energy rays, the rubber layer is simultaneously modified and cured. In particular, rubber having a double bond in the rubber layer is preferable because it has a large effect of modification and curing by irradiation with active energy rays.

  Here, a method for forming the outermost surface layer by crosslinking and curing by ultraviolet irradiation will be described in detail.

The rubber roller coated with the outermost surface layer coating liquid is rotated at a constant rotational speed and irradiated with ultraviolet rays. Here, the schematic diagram of an example of the ultraviolet irradiation processing apparatus which can be used for FIG. 4 at this invention is shown. The rubber roller 6 coated with the coating solution for the outermost surface layer is rotated at a constant rotational speed by the roller rotating member 14, and the surface is irradiated with ultraviolet rays from the ultraviolet irradiation port 15. For irradiation with ultraviolet rays, a high pressure mercury lamp, a metal halide lamp, a low pressure mercury lamp, or an excimer UV lamp is used. Further, when these lamps are used, the ultraviolet intensity at a wavelength of 150 to 400 nm is 60% or more of the total wavelength intensity, and it is possible to perform ultraviolet irradiation promptly. The integrated light quantity of ultraviolet rays is defined below.
UV integrated light quantity (mJ / cm ² ) = UV intensity (mW / cm ² ) × irradiation time (sec)
What is necessary is just to select suitably about the integrated light quantity of an ultraviolet-ray according to the effect of surface treatment. The adjustment can be performed by any of irradiation time, lamp output, and distance between the lamp and the rubber roller, and may be determined so as to obtain a desired integrated light quantity. Further, the integrated light quantity may be graded within the irradiation time.

  The reflecting plate 16 may be disposed outside the ultraviolet lamp, and the reflecting plate is made of aluminum, stainless steel, or iron, and the reflecting surface is mirror-finished or coated or surface-treated to improve reflectivity. Things are desirable. Preferably, the surface is made of high purity aluminum having a material of 99.9% or more, and the surface is subjected to gloss alumite treatment having a reflectance of 90% or more. The distance between the reflecting plate and the rubber roller can be arbitrarily set, and is determined in consideration of the influence of heat by ultraviolet integrated light quantity and radiation from the reflecting plate.

  As for the ultraviolet irradiation method, a plurality of rubber rollers coated with a coating solution for the outermost surface layer are arranged concentrically around a tubular ultraviolet lamp, and a cylindrical or arc-shaped reflector on the outer concentric circle. A method of irradiating ultraviolet rays while rotating the rubber roller may be used.

  In the present invention, with respect to ultraviolet rays typified by a wavelength of 254 nm, the integrated light amount of ultraviolet rays is measured by an ultraviolet integrated light meter (UIT-150-A (trade name), UVD-S254 (trade name)) manufactured by Ushio Electric Co., Ltd. It measured using. In addition, for ultraviolet rays typified by a wavelength of 172 nm, the integrated light amount of ultraviolet rays is measured using an ultraviolet integrated light meter (UIT-150-A (trade name), VUV-S172 (trade name)) manufactured by USHIO INC. It was measured. Furthermore, for ultraviolet rays typified by a wavelength of 365 nm, the accumulated light amount of ultraviolet rays is measured using an ultraviolet ray integrated light meter (UIT-150-A (trade name), VUV-S365 (trade name)) manufactured by USHIO INC. did.

The resistance value of the charging rubber roller described in the above embodiment of the present invention was measured by applying a weight of 500 g to both ends of the cored bar and rotating the charging roller in a driven manner while rotating in contact with the metal drum. The resistance value of the charged rubber roller when a voltage of 200 V was applied to the metal core and the metal drum was adjusted to 10 ³ to 10 ⁸ Ω. The charging rubber roller described in the embodiment of the present invention is used as an electrophotographic member of an image forming apparatus such as an LBP (Laser Beam Printer), a copying machine, or a facsimile.

  Here, FIG. 5 shows a usage pattern when the charging rubber roller of the present invention is used as a charging roller. The image forming apparatus shown in FIG. 5 is a rotary drum type / transfer type electrophotographic apparatus, and 17 is an electrophotographic photosensitive member (photosensitive drum) as an image carrier, and has a predetermined peripheral speed in the clockwise direction. Rotation driven with (process speed). The photosensitive drum 17 is uniformly charged to a predetermined polarity and potential (-600 V in this embodiment) by a charging roller 18 to which a charging bias is applied from a power source E1 as a charging means during the rotation process. Next, the exposure system 19 receives negative image exposure (analog exposure of the original image, digital scanning exposure) corresponding to the target image information, and an electrostatic latent image of the target image information is formed on the peripheral surface. Next, the electrostatic latent image is developed as a toner image by the developing roller 20 of the reverse development method using minus toner. First, a transfer material is fed at a predetermined timing from a sheet feeding unit (not shown) to a transfer portion between the photosensitive drum 17 and a transfer roller 21 as a transfer unit. Then, a transfer bias of about +2 to 3 KV is applied to the transfer roller 21 from the power source E2, and the toner image subjected to the reverse development on the surface of the photosensitive drum 17 is sequentially transferred to the transfer material. The transfer material that has received the transfer of the toner image is separated from the surface of the photosensitive drum 17 and is introduced into fixing means (not shown) to undergo image fixing processing. The surface of the photosensitive drum after the transfer of the toner image is subjected to a removal process of adhering contaminants such as transfer residual toner by the cleaning unit 22 to be cleaned and repeatedly used for image formation.

  Further, a process cartridge may be configured in which the photosensitive drum 17 as the image carrier and the charging roller 18 as the charging member are integrally supported and are detachable from the main body of the image forming apparatus.

The surface roughness Rzjis measurement of the rubber roller in the present invention is a method according to the ten-point average roughness evaluation in JIS94-B0601, using a surface roughness measuring instrument SE-3400 manufactured by Kosaka Laboratory,
Cut off 0.8mm,
Measuring speed 0.5 mm / s,
Measurement length is 8mm
As measured. Here, the length of the charged portion of the conductive elastic body / (8 mm) N (N is an integer part, N ≧ 3), the conductive elastic layer was divided into N and divided into N in the longitudinal direction of the rubber roller. Six points were measured every 60 ° in the circumferential direction of each part (the above-mentioned “six-point measurement in the circumferential direction”). And the surface roughness Rzjis-ave. Of each part which divided N average value of 6 points | pieces. (FIG. 6). FIG. 7 shows the surface roughness distribution in the longitudinal direction of the charged portion of the conductive elastic body.

  In the present invention, the pressure distribution in the contact nip between the rubber roller and the photosensitive drum is measured by sandwiching a film-like sensor having a thickness of 100 μm between the rubber roller and the photosensitive drum using the NITTA Tactile Sensor System. went.

  In the measurement of the film thickness of the outermost surface layer in the present invention, several points were measured at a magnification of 10,000 times using a scanning electron microscope (SEM), and the average value was taken as the SEM average film thickness.

  The measurement was performed in an environment of 23.5 ° C./60%.

The charging rubber roller described in the embodiment of the present invention is a conductive roller having a cored bar and a conductive elastic layer (rubber layer) formed on the cored bar. The surface roughness Rzjis in the longitudinal direction of the conductive elastic layer is 2.0 to 20.0 μm, more preferably 2.0 to 12.0 μm, and has the following relationship (A).
(A) (the length of the charged portion of the conductive elastic body) / (8 mm) = N (N is an integer part rounded up after the decimal point, N ≧ 3). 1 to N. At this time, the surface roughness Rzjis-ave. (1) and Rzjis-ave. (N) is 2.0 to 7.0 μm, and Rzjis-ave. At least one point of (2-N-1) has a surface roughness Rzjis-ave. (1) and Rzjis-ave. It is 1.2 to 5.0 times (preferably 1.5 to 3.0 times) of (N). Preferably, the surface roughness Sm-ave. Is 30 to 130 μm.

  Furthermore, the surface roughness Rzjis-ave. However, there is a maximum value in the divided portion within the range of (N / 2) −3 to (N / 2) +3, and the surface roughness Rzjis-ave. (1) and Rzjis-ave. (N) becomes smaller with an inclination. That is, the surface roughness Rzjis-ave. Becomes the maximum value in the central portion, and becomes smaller by inclining from the central portion to both ends (N / 2 is an integer portion rounded up after the decimal point, N ≧ 7).

  Here, for example, when the surface roughness Rzjis in the longitudinal direction of the rubber roller is larger than 20.0 μm, the surface roughness is very large, so that the surface of the rubber roller is contaminated by the toner and the external additive attached to the toner. The surface of the drum may not be uniformly charged. On the other hand, if it is smaller than 2.0 μm, there is a possibility that minute discharge in the vicinity of the contact nip with the photosensitive drum and in the contact nip is reduced, and the surface of the photosensitive drum cannot be uniformly charged.

  Further, although depending on the crown shape of the rubber roller, when the surface roughness Rzjis at both ends in the longitudinal direction of the rubber roller is larger than 5.0 times the surface roughness Rzjis at the central portion, the surface of the rubber roller has toner and toner at the central portion. It becomes easy to get dirty by the external additive adhering to. On the other hand, if it is smaller than 1.2 times, the surface may be soiled at both ends of the rubber roller depending on the size of the surface roughness Rzjis.

  As described above, by controlling the surface roughness Rzjis, particularly the surface roughness Rzjis in the longitudinal direction, the surface roughness is high in the portion where the pressure is high in accordance with the pressure distribution in the contact nip between the charging roller and the photosensitive drum. The surface roughness becomes large at a portion where the pressure is small and the pressure is small. By doing so, it is possible to provide a charging member that can stably charge the photosensitive drum while suppressing contamination of the surface of the charging roller due to toner and an external additive attached to the toner, in particular, contamination at both ends of the longitudinal direction. it can. Here, FIG. 8 shows an example of a schematic view of a cross section of the charging rubber roller of the present invention. 4 is a metal core, 23 is an elastic layer (rubber layer), and 24 is an outermost surface layer.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these.

[Example 1]
<Production of rubber roller>
The following raw materials were kneaded with a pressure kneader for 15 minutes.
・ NBR 100 parts by mass (trade name “Nipol DN219”: manufactured by Nippon Zeon Co., Ltd.)
Carbon black 1 14 parts by mass (trade name “Asahi HS-500”: manufactured by Asahi Carbon Co., Ltd.)
・ Carbon black 2 4 parts by mass (Brand name “Ketjen Black EC600JD” manufactured by Lion Corporation)
・ Zinc stearate 1 part by mass ・ Zinc oxide 5 parts by mass ・ Calcium carbonate 30 parts by mass (trade name “Nanox # 30” manufactured by Maruo Calcium Co., Ltd.)
Furthermore,
1 part by mass of a vulcanization accelerator (DM: di-2-benzothiazolyl disulfide),
An unvulcanized rubber composition was prepared by adding 3 parts by mass of a vulcanization accelerator (TBzTD: tetrabenzylthiuram disulfide) and 1.2 parts by mass of sulfur as a vulcanizing agent and kneading with an open roll for 15 minutes. Subsequently, a stainless bar core bar having an outer diameter of 6 mm and a length of 252 mm was prepared. Here, the core metal and the unvulcanized rubber composition were integrally extruded using an extruder schematically shown in FIG. 1 to form a rubber roller. Thereafter, heat vulcanization was performed at 160 ° C. for 2 hours, and further, traverse polishing was performed.

Contacting the rubber roller rotating at a speed of 400 rpm while rotating the grindstone at a speed of 1570 rpm, and
The moving speed of the contacted grindstone is increased from 50 mm / min from one end side of the rubber roller toward the central part to 200 mm / min, and the moving speed is decreased to 50 mm / min toward the other end beyond the central part. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-120 (manufactured by Noritake). A rubber roller having a thickness of 1.25 mm and a length of 232 mm was obtained by cutting and removing the end (rubber roller outer diameter φ8.5 mm, crown amount 110 μm, conductive elastic layer thickness 1.25 mm). Further, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Here, from (the length of the charged portion of the conductive elastic body = 232 mm) / (8 mm) = 29, the conductive elastic layer was divided into 29, and the number was set to 1 to N in order from one end. Surface roughness Rzjis-ave. Of the surface roughness Rzjis-ave. (1) = 2.7 μm, Sm-ave. (1) = 55 μm, surface roughness Rzjis-ave. (29) = 2.9 μm, Sm-ave. (29) = 53 μm and the surface roughness Rzjis-ave. (15) = 5.2 μm, Sm-ave. (15) = 107 μm and surface roughness Rzjis-ave. 1.9 times of (1), surface roughness Rzjis-ave. It was 1.8 times of (29). Further, the surface roughness Rzjis-ave. (15) is the maximum value in the longitudinal direction of the rubber roller, and the surface roughness Rzjis-ave. (15) surface roughness Rzjis-ave. (1) and surface roughness Rzjis-ave. Toward (29), the surface roughness Rzjis-ave. Is smaller and smaller. These results are summarized in Table 1.

  Further, this charging rubber roller was incorporated in the electrophotographic image forming apparatus shown in FIG. 4 as a charging roller, and pressed against both ends of the photosensitive drum with a load of 500 g applied. Then, continuous 6000 sheets (sometimes referred to as 6K) were passed through halftone images in an environment of 23.5 ° C./60%, and the following durable stain image evaluation was performed. The obtained results are shown in Table 2.

<Durable stain image evaluation>
An initial image was formed between 1 to 10 sheets and a durable image was formed between 6000 continuous sheets. The presence or absence of dot-like or line-like image defects due to toner or external additives fixed to the charged rubber roller, or black or white horizontal stripe-like image defects due to charging unevenness was visually observed and inspected. Based on the obtained inspection results, image evaluation was performed according to the following criteria.
A: No image defect at all B: Image defect is very rare C: Image defect is abundant.

[Example 2]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the traverse polishing conditions of Example 1 were as follows (outer diameter of rubber roller: 8.5 mm, crown amount: 110 μm, conductive elastic layer thickness: 1.25 mm).

Contacting the rubber roller rotating at a speed of 200 rpm while rotating the grindstone at a speed of 1570 rpm, and
Increase the moving speed of the contacted grinding wheel from one end side of the rubber roller from the moving speed of 50 mm / min toward the central part to 200 mm / min, and lower the moving speed to the other end side beyond the central part to 50 mm / min. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

[Example 3]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the traverse polishing conditions of Example 1 were as follows (outer diameter of rubber roller: 8.5 mm, crown amount: 110 μm, conductive elastic layer thickness: 1.25 mm).

Contacting the rubber roller rotating at a speed of 100 rpm while rotating the grindstone at a speed of 1570 rpm, and
The contact speed of the grindstone is increased from 10 mm / min from one end side of the rubber roller toward the central portion, the moving speed is increased to 600 mm / min, and the moving velocity is reduced to 10 mm / min beyond the central portion toward the other end side. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

[Example 4]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the polishing conditions of the traverse method of Example 1 were as follows (rubber roller outer diameter φ7 mm, crown amount 70 μm, conductive elastic layer thickness 0.5 mm).

Contacting the rubber roller rotating at a speed of 500 rpm while rotating the grindstone at a speed of 1570 rpm, and
Increase the moving speed of the contacted grinding wheel from one end side of the rubber roller from the moving speed of 50 mm / min toward the central part to 200 mm / min, and lower the moving speed to the other end side beyond the central part to 50 mm / min. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-120 (manufactured by Noritake).

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

[Example 5]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the traverse polishing conditions of Example 1 were as follows (rubber roller outer diameter φ8.5 mm, crown amount 90 μm, conductive elastic layer thickness 1.25 mm).

Contacting the rubber roller rotating at a speed of 200 rpm while rotating the grindstone at a speed of 1570 rpm, and
The contact speed of the grindstone is increased from 200 mm / min from one end side of the rubber roller toward the central portion, the moving speed is increased to 250 mm / min, and the moving speed is decreased to 200 mm / min beyond the central portion toward the other end side. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

[Example 6]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the traverse polishing conditions of Example 1 were as follows (rubber roller outer diameter φ8.5 mm, crown amount 90 μm, conductive elastic layer thickness 1.25 mm).

Contacting the rubber roller rotating at a speed of 200 rpm while rotating the grindstone at a speed of 1570 rpm, and
The contact speed of the grindstone is increased from one end of the rubber roller to 20 mm / min from the moving speed 20 mm / min toward the center, and the moving speed is decreased to 20 mm / min beyond the center toward the other end. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

[Example 7]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the traverse polishing conditions of Example 1 were as follows (rubber roller outer diameter φ8.5 mm, crown amount 90 μm, conductive elastic layer thickness 1.25 mm).

Contacting the rubber roller rotating at a speed of 400 rpm while rotating the grindstone at a speed of 1570 rpm, and
The moving speed of the contacted grindstone is increased from 200 mm / min from one end of the rubber roller toward the central portion to 400 mm / min, and the moving speed is decreased to 200 mm / min toward the other end beyond the central portion. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

[Example 8]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the traverse polishing conditions of Example 1 were as follows (rubber roller outer diameter φ8.5 mm, crown amount 90 μm, conductive elastic layer thickness 1.25 mm).

Contacting the rubber roller rotating at a speed of 200 rpm while rotating the grindstone at a speed of 1570 rpm, and
The moving speed of the contacted grindstone is increased from 20 mm / min from one end of the rubber roller toward the central portion to 300 mm / min, and the moving velocity is reduced to 20 mm / min beyond the central portion toward the other end. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake). Here, the pressure distribution in the contact nip between the rubber roller and the photosensitive drum is measured in advance with a rubber roller having a crown amount of 90 μm, and the surface roughness is reduced in a portion where the pressure is high, and the surface roughness is reduced in a portion where the pressure is low. The polishing conditions (the moving speed of the grindstone) were adjusted so as to increase. Pressure distribution in the contact nip between the rubber roller and the photosensitive drum and the surface roughness in the longitudinal direction Rzjis-ave. The relationship is shown in FIG.

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

[Example 9]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the polishing conditions of the traverse method of Example 1 were as follows (rubber roller outer diameter φ8.5 mm, crown amount 150 μm, conductive elastic layer thickness 1.25 mm).

Contacting the rubber roller rotating at a speed of 400 rpm while rotating the grindstone at a speed of 1570 rpm, and
The moving speed of the contacted grinding wheel is increased from 100 mm / min from one end side of the rubber roller toward the central part to 200 mm / min, and the moving speed is decreased to 100 mm / min toward the other end side beyond the central part. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake). Here, the pressure distribution in the contact nip between the rubber roller and the photosensitive drum is measured in advance with a rubber roller having a crown amount of 150 μm, and the surface roughness is reduced in a portion where the pressure is high, and the surface roughness is reduced in a portion where the pressure is low. The polishing conditions (the moving speed of the grindstone) were adjusted so as to increase. Pressure distribution in the contact nip between the rubber roller and the photosensitive drum and the surface roughness in the longitudinal direction Rzjis-ave. The relationship is shown in FIG.

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

[Example 10]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 (rubber roller outer diameter φ8.5 mm, crown amount 110 μm, conductive elastic layer thickness 1.25 mm).

<Method for forming outermost surface layer>
The following raw materials were prepared.
・ Glycidoxypropyltriethoxysilane (GPTES): 27.84 g (0.1 mol)
-Methyltriethoxysilane (MTES): 17.83 g (0.1 mol)
Tridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane (FTS, carbon number of perfluoroalkyl group 6): 7.68 g (0.0151 mol) (7 mol based on the total amount of hydrolyzable silane compounds) % Equivalent)
・ Water: 17.43g
・ Ethanol: 37.88 g
After mixing the raw materials, the mixture was stirred at room temperature and then heated to reflux for 24 hours to hydrolyze and condense the hydrolyzable silane compound to obtain a hydrolyzable condensate. By adding this hydrolyzable condensate to a mixed solvent of 2-butanol / ethanol, a hydrolyzable condensate-containing alcohol solution having a solid content of 7% by mass was prepared. To 100 g of this hydrolyzable condensate-containing alcohol solution, 0.35 g of an aromatic sulfonium salt (trade name: Adekaoptomer SP-150, manufactured by Asahi Denka Kogyo Co., Ltd.) as a photocationic polymerization initiator was added. . Furthermore, it diluted with ethanol so that it might become 2.0 mass% of solid content, and prepared the coating liquid for outermost layers.

The outermost surface layer coating liquid is placed in a sealed container, the sealed container is connected to a syringe pump as a liquid supply means, and further connected to one liquid supply port provided in the ring head, so that an appropriate amount of coating liquid is placed in the ring head. Supplied. The coating liquid was filled in a ring head having a liquid distribution chamber for merging and distributing in the circumferential direction in the ring head. The rubber roller obtained above was supported in a vertical state, and the ring head was arranged so that a slit-like discharge port opened on the entire circumference at a distance of 0.5 mm from the outer diameter of the rubber roller. . At this time, the opening width (slit width) of the slit-like discharge port opened on the entire circumference of the ring head was 0.1 mm. The ring head is vertically moved from the upper end to the lower end of the rubber roller at a constant speed of 70 mm / s, and at the same time, an appropriate amount (0.07 mL) of the coating solution for the outermost surface layer is completely discharged at a discharge speed of 0.018 mL / s. It was applied evenly around the circumference. Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Here, from (the length of the charged portion of the conductive elastic body = 232 mm) / (8 mm) = 29, the conductive elastic layer was divided into 29, and the number was set to 1 to N in order from one end. Surface roughness Rzjis-ave. Of the surface roughness Rzjis-ave. (1) = 2.6 μm, Sm-ave. (1) = 44 μm, surface roughness Rzjis-ave. (29) = 2.9 μm, Sm-ave. (29) = 51 μm and the surface roughness Rzjis-ave. (15) = 5.3 μm, Sm-ave. (15) = 95 μm and surface roughness Rzjis-ave. 2.0 times of (1), surface roughness Rzjis-ave. It was 1.8 times of (29). Further, the surface roughness Rzjis-ave. (15) is the maximum value in the longitudinal direction of the rubber roller, and the surface roughness Rzjis-ave. (15) surface roughness Rzjis-ave. (1) and surface roughness Rzjis-ave. Toward (29), the surface roughness Rzjis-ave. Is smaller and smaller.

  The SEM average film thickness of the outermost surface layer of the rubber roller measured at a magnification of 10,000 times with a scanning electron microscope (SEM) was 70 nm. These results are summarized in Table 1.

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Table 2.

[Example 11]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the polishing conditions of the traverse method of Example 1 were as follows (rubber roller outer diameter φ12 mm, crown amount 160 μm, conductive elastic layer thickness 3.0 mm).

Contacting the rubber roller rotating at a speed of 400 rpm while rotating the grindstone at a speed of 1570 rpm, and
The moving speed of the contacted grinding wheel is increased from 100 mm / min from one end side of the rubber roller toward the central portion, and the moving speed is increased to 400 mm / min from the one end side to the central portion, and the moving speed is decreased to 100 mm / min beyond the central portion toward the other end side. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

  Thereafter, a charged rubber roller was obtained in the same manner as in Example 10 except that the solid content of the outermost surface layer coating solution was changed to 5.0% by mass. Further, the obtained rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 10. The obtained results are shown in Tables 1 and 2.

[Example 12]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the polishing conditions of the traverse method of Example 1 were as follows (rubber roller outer diameter φ8.5 mm, crown amount 80 μm, conductive elastic layer thickness 1.25 mm).

Contacting the rubber roller rotating at a speed of 200 rpm while rotating the grindstone at a speed of 1570 rpm, and
The moving speed of the contacted grinding wheel is increased from 200 mm / min from one end of the rubber roller toward the central portion to 500 mm / min, and the moving velocity is decreased to 200 mm / min beyond the central portion toward the other end. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

  Thereafter, a charged rubber roller was obtained in the same manner as in Example 10 except that the solid content of the outermost surface layer coating solution was changed to 1.0% by mass. Further, the obtained rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 10. The obtained results are shown in Tables 1 and 2.

[Example 13]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the unvulcanized rubber composition of Example 1 and the polishing conditions of the traverse method were as follows (rubber roller outer diameter φ8.5 mm, crown amount 90 μm, conductive elastic layer) Thickness of 1.25 mm).

<Preparation of unvulcanized rubber composition>
The following raw materials were kneaded with an open roll for 30 minutes.
・ 100 parts by mass of epichlorohydrin rubber (trade name “Epichromer CG102”: manufactured by Daiso Corporation)
・ MT carbon 30 parts by mass (trade name “HTC # 20”: made by Nisshin Carbon)
・ Zinc oxide 5 parts by mass ・ Stearic acid 1 part by mass
1 part by mass of a vulcanization accelerator (DM: di-2-benzothiazolyl disulfide),
A vulcanization accelerator (TS: tetramethylthiuram monosulfide) 0.5 parts by mass and sulfur 1.2 parts by mass were added and kneaded with an open roll for 15 minutes to prepare an unvulcanized rubber composition. .

<Traverse polishing conditions>
Contacting the rubber roller rotating at a speed of 300 rpm while rotating the grindstone at a speed of 1570 rpm, and
The contact speed of the grindstone is increased from 20 mm / min from one end of the rubber roller to 200 mm / min from the moving speed toward the center, and the moving speed is decreased to 20 mm / min beyond the center toward the other end. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-120 (manufactured by Noritake).

  Thereafter, a charged rubber roller was obtained in the same manner as in Example 10 except that the solid content of the coating solution for the outermost surface layer was changed to 18.0% by mass. Further, the obtained rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 10. The obtained results are shown in Tables 1 and 2.

[Comparative Example 1]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Example 1 except that the unvulcanized rubber composition of Example 1 and the polishing conditions of the traverse method were as follows (rubber roller outer diameter φ8.5 mm, crown amount 110 μm, conductive elastic layer) Thickness of 1.25 mm).

<Preparation of unvulcanized rubber composition>
The following raw materials were kneaded with an open roll for 30 minutes.
・ 100 parts by mass of epichlorohydrin rubber (trade name “Epichromer CG102”: manufactured by Daiso Corporation)
-MT carbon 5 parts by mass (trade name “HTC # 20”: made by Nisshin Carbon)
・ Zinc oxide 5 parts by mass ・ Stearic acid 1 part by mass
1 part by mass of a vulcanization accelerator (DM: di-2-benzothiazolyl disulfide),
A vulcanization accelerator (TS: tetramethylthiuram monosulfide) 0.5 parts by mass and sulfur 1.2 parts by mass were added and kneaded with an open roll for 15 minutes to prepare an unvulcanized rubber composition. .

<Traverse polishing conditions>
By rotating the grindstone at a speed of 1570 rpm and contacting a rubber roller rotating at a speed of 400 rpm, and moving the contacted grindstone from one end side of the rubber roller toward the other end side at a moving speed of 20 mm / min. Polishing was performed. The grindstone used at this time was GC-120 (manufactured by Noritake).

  Then, the mixed solution which uses methyl isobutyl ketone adjusted so that the solid content of urethane resin (polycaprolactone-type polyol, tolylene diisocyanate; TDI) may be about 20% was prepared. And 55 mass parts electroconductive carbon was further added with respect to 100 mass parts of urethane resin components to this prepared mixed solution, and it stirred sufficiently and was used as the coating liquid. An immersion tank was prepared in which about 300 mL of this coating solution was placed in a glass container (Φ40 mm, length 350 mm). The rubber roller was disposed so as to be approximately at the center of the immersion tank, and the rubber roller was moved to immerse the elastic layer portion of the rubber roller in the coating solution. After dipping for several seconds, the rubber roller was pulled up at a speed of 10 to 20 mm / s (dip coating). Thereafter, the rubber roller was air-dried at room temperature for 30 minutes, and further dried in a hot air circulating dryer at a temperature of 160 ° C. for 1 hour and cured to obtain a charged rubber roller.

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

  As shown in Table 2, in the charged rubber roller of this comparative example, an image defect due to charging unevenness was confirmed in a durable image after 5000 continuous sheets (may be represented as 5K) (B). Although there is deterioration due to energization during durability, since the surface roughness of the charging rubber roller of this comparative example is small, minute discharge in the vicinity of the contact nip with the photosensitive drum and in the contact nip is reduced, There is a possibility that the surface of the photosensitive drum cannot be uniformly charged.

[Comparative Example 2]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Comparative Example 1 except that the traverse polishing conditions of Comparative Example 1 were as follows (outer diameter of rubber roller: 8.5 mm, crown amount: 110 μm, conductive elastic layer thickness: 1.25 mm).

Contacting the rubber roller rotating at a speed of 200 rpm while rotating the grindstone at a speed of 1570 rpm, and
Polishing was performed by moving the contacted grindstone from one end side of the rubber roller toward the other end side at a moving speed of 150 mm / min. The grindstone used at this time was GC-80 (manufactured by Noritake).

  Then, the mixed solution which uses methyl isobutyl ketone adjusted so that the solid content of urethane resin (polycaprolactone-type polyol, tolylene diisocyanate; TDI) may be about 20% was prepared. Further, 55 parts by mass of conductive carbon and 30 parts by mass of acrylic particles having an average particle diameter of 5 μm are added to 100 parts by mass of the urethane resin component to the prepared mixed solution. did. An immersion tank was prepared in which about 300 mL of this coating solution was placed in a glass container (Φ40 mm, length 350 mm). The rubber roller was disposed so as to be approximately at the center of the immersion tank, and the rubber roller was moved to immerse the elastic layer portion of the rubber roller in the coating solution. After dipping for several seconds, the rubber roller was pulled up at a speed of 10 to 20 mm / s (dip coating). Thereafter, the rubber roller was air-dried at room temperature for 30 minutes, and further dried in a hot air circulating dryer at a temperature of 160 ° C. for 1 hour and cured to obtain a charged rubber roller.

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

  As shown in Table 2, in the charged rubber roller of this comparative example, an image defect due to durable stain was confirmed at both ends in a durable image after 2000 continuous sheets (sometimes represented as 2K) (B). . In addition, spot-like or linear stains due to toner and external additives fixed at both ends of the surface of the charged rubber roller were confirmed (B).

[Comparative Example 3]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Comparative Example 1 (rubber roller outer diameter φ8.5 mm, crown amount 90 μm, conductive elastic layer thickness 1.25 mm).

  Then, the mixed solution which uses methyl isobutyl ketone adjusted so that the solid content of urethane resin (polycaprolactone-type polyol, tolylene diisocyanate; TDI) may be about 20% was prepared. And 70 mass parts electroconductive carbon was further added with respect to 100 mass parts of urethane resin components to this prepared mixed solution, and it fully stirred and disperse | distributed and was set as the coating liquid. An immersion tank was prepared in which about 300 mL of this coating solution was placed in a glass container (Φ40 mm, length 350 mm). The rubber roller was disposed so as to be approximately at the center of the immersion tank, and the rubber roller was moved to immerse the elastic layer portion of the rubber roller in the coating solution. After dipping for several seconds, the rubber roller was pulled up at a speed of 10 to 20 mm / s (dip coating). Thereafter, the rubber roller was air-dried at room temperature for 30 minutes, and further dried in a hot air circulating dryer at a temperature of 160 ° C. for 1 hour and cured to obtain a charged rubber roller.

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

  As shown in Table 2, in the charging rubber roller of this comparative example, an image defect due to charging unevenness was confirmed in a durable image after 5500 continuous sheets (sometimes referred to as 5.5K) (B). Although there is deterioration due to energization during durability, since the surface roughness of the charging rubber roller of this comparative example is small, minute discharge in the vicinity of the contact nip with the photosensitive drum and in the contact nip is reduced, There is a possibility that the surface of the photosensitive drum cannot be uniformly charged.

[Comparative Example 4]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Comparative Example 1 except that the traverse polishing conditions of Comparative Example 1 were as follows (outer diameter of rubber roller φ8.5 mm, crown amount 90 μm, conductive elastic layer thickness 1.25 mm).

Contacting the rubber roller rotating at a speed of 100 rpm while rotating the grindstone at a speed of 1570 rpm, and
The moving speed of the contacted grindstone from one end side of the rubber roller is increased from the moving speed of 50 mm / min toward the central part to 800 mm / min, and the moving speed is decreased to the other end side beyond the central part to 50 mm / min. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

  As shown in Table 2, in the charged rubber roller of this comparative example, an image defect due to durable dirt was confirmed in the central portion of a durable image after 1500 continuous sheets (sometimes referred to as 1.5K). C). In addition, dot-like or linear stains due to toner and external additives fixed at the center of the surface of the charged rubber roller were confirmed (C).

[Comparative Example 5]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Comparative Example 1 except that the traverse polishing conditions of Comparative Example 1 were as follows (outer diameter of rubber roller: 8.5 mm, crown amount: 110 μm, conductive elastic layer thickness: 1.25 mm).

Contacting the rubber roller rotating at a speed of 100 rpm while rotating the grindstone at a speed of 1570 rpm, and
The contact speed of the grindstone is increased from 5 mm / min from one end of the rubber roller to 700 mm / min from the moving speed toward the center, and the moving speed is decreased to 5 mm / min toward the other end beyond the center. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

  As shown in Table 2, in the charged rubber roller of this comparative example, an image defect due to durable stain was confirmed in the central portion of a durable image after 5000 continuous sheets (sometimes referred to as 5K) (B). .

[Comparative Example 6]
<Production of rubber roller>
A rubber roller was obtained in the same manner as in Comparative Example 1 except that the traverse polishing conditions of Comparative Example 1 were as follows (outer diameter of rubber roller φ8.5 mm, crown amount 90 μm, conductive elastic layer thickness 1.25 mm).

Contacting the rubber roller rotating at a speed of 200 rpm while rotating the grindstone at a speed of 1570 rpm, and
The moving speed of the grindstone contacted from one end side of the rubber roller is reduced from 10 mm / min to 10 mm / min from the moving speed of 150 mm / min toward the center, and the moving speed is increased to 150 mm / min beyond the center to the other end. Polishing was performed by moving in the manner described above. The grindstone used at this time was GC-80 (manufactured by Noritake).

Thereafter, ultraviolet irradiation with a low-pressure mercury lamp (manufactured by Harrison Toshiba Lighting) was performed for 5 minutes. Regarding the low-pressure mercury lamp, the ultraviolet light mainly represented by a wavelength of 254 nm was used, and the UV integrated light quantity at this time was about 10,000 mJ / cm ² (UV intensity was 35 mW / cm ² ).

  Further, the obtained charged rubber roller was measured for physical properties and evaluated for durability image in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

  As shown in Table 2, in the charged rubber roller of this comparative example, an image defect due to durable stain was confirmed at both ends in a durable image after 5000 continuous sheets (sometimes referred to as 5K) (B). .

It is a schematic diagram which shows an example of the manufacturing method of the rubber roller by an extrusion method. It is a schematic diagram of an example of the manufacturing method of the rubber roller by grinding | polishing of a traverse method. It is a schematic diagram which shows an example of the ring head coating method. It is a schematic diagram which shows an example of an ultraviolet irradiation device. 1 is a configuration diagram showing an outline of an example of an image forming apparatus of the present invention. It is a schematic diagram which shows the division | segmentation method of the charging site | part of the electroconductive elastic body of this invention. It is a schematic diagram which shows the surface roughness distribution in the longitudinal direction of the charging site | part of the electroconductive elastic body of this invention. It is a schematic diagram which shows an example of the charging rubber roller cross section of this invention. Pressure distribution in the contact nip between the rubber roller and the photosensitive drum and the surface roughness in the longitudinal direction Rzjis-ave. It is a figure which shows the relationship. Pressure distribution in the contact nip between the rubber roller and the photosensitive drum and the surface roughness in the longitudinal direction Rzjis-ave. It is a figure which shows the relationship.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extruder 2 Crosshead 3 Core metal feed roller 4 Core metal 5 Cutting / removal processing 6 Rubber roller 7 Rotating mounting member 8 Grinding stone 9 Ring head 10 Slit-like discharge port 11 opened to the entire circumference 11 Liquid throttle part 12 Liquid supply port 13 Liquid distribution chamber 14 Roller rotating member 15 Ultraviolet irradiation port 16 Reflecting plate 17 Electrophotographic photosensitive member (photosensitive drum)
18 Charging roller (charging means)
19 Exposure system 20 Developing roller (developing means)
21 Transfer roller (transfer means)
22 Cleaning means E1, E2, E3 Power supply for bias application 23 Elastic layer (rubber layer)
24 outermost layer

Claims (12)

A charging member having a conductive elastic layer on a conductive substrate is characterized in that the surface roughness Rzjis in the longitudinal direction of the conductive elastic layer is 2.0 to 20.0 μm and the following relationship (A) is satisfied. And charging member.
(A) (the length of the charged portion of the conductive elastic body) / (8 mm) = N (N is an integer part rounded up after the decimal point, N ≧ 3). 1 to N. At this time, the surface roughness Rzjis-ave. (1) and Rzjis-ave. (N) is 2.0 to 7.0 μm, and Rzjis-ave. At least one point of (2-N-1) has a surface roughness Rzjis-ave. (1) and Rzjis-ave. It is 1.2 to 5.0 times (N).
(Surface roughness Rzjis is JIS94-B0601 ten-point average roughness)
(Surface roughness Rzjis-ave. Is an average value of six measurements in the circumferential direction)   The charging member according to claim 1, wherein a surface roughness Rzjis in a longitudinal direction of the conductive elastic layer is 2.0 to 12.0 μm.   Of the surface roughness Rzjis (2 to N-1) in the longitudinal direction of the conductive elastic layer, at least one point is Rzjis-ave. (1) and Rzjis-ave. The charging member according to claim 1, which is 1.5 to 3.0 times as long as (N).   Surface roughness Sm-ave in the longitudinal direction of the conductive elastic layer. The charging member according to claim 1, wherein is 30 to 130 μm. Surface roughness Rzjis-ave. In the longitudinal direction of the conductive elastic layer. However, there is a maximum value in the divided portion within the range of (N / 2) −3 to (N / 2) +3, and the surface roughness Rzjis-ave. (1) and Rzjis-ave. The charging member according to any one of claims 1 to 4, wherein the charging member is smaller in inclination with respect to (N).
(N / 2 is an integer part rounded up after the decimal point, N ≧ 7) In the charging member, the outer diameter at one end in the longitudinal direction is D1 (μm), the outer diameter at the center is D2 (μm), and the outer diameter at the other end in the longitudinal direction is D3 ( μm)
6. The charging member according to claim 1, wherein D2- (D1 + D3) / 2 has a crown shape of 70 μm or more and 160 μm or less.
(D2 (μm) is the outer diameter of the central portion of the charging member, D1 and D3 (μm) are the outer diameters at the end in the longitudinal direction of the charging member, and both ends D1, D3 from the central portion are from the central portion. (Each 90mm position in each direction.)   The charging member according to claim 1, wherein a thickness of the conductive elastic layer is 0.5 to 3.0 mm.   The charging member according to claim 1, further comprising an outermost surface layer having a thickness of 10 nm or more and 1000 nm or less on the conductive elastic layer. Electrophotographic photoreceptor,
Means for charging the surface of the electrophotographic photoreceptor;
Means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image;
Means for developing the electrostatic latent image to form a toner image; and
An image forming apparatus having transfer means for transferring the toner image to the surface of a transfer material,
9. An image forming apparatus, wherein the transfer unit has the charging member according to claim 1 as a charging member for charging the transfer material. The pressure in the contact nip of the charging member with the photosensitive drum has a minimum value within the range of (N / 2) −3 to (N / 2) +3, and R (1) and R from the minimum value. The image forming apparatus according to claim 9, wherein the image forming apparatus increases in inclination with respect to (N).
(N / 2 is an integer part rounded up after the decimal point, N ≧ 7)   A process cartridge that integrally supports an image carrier and the charging member according to claim 1 and is detachable from an image forming apparatus main body. The pressure in the contact nip of the charging member with the photosensitive drum has a minimum value within the range of (N / 2) −3 to (N / 2) +3, and R (1) and R from the minimum value. The process cartridge according to claim 11, wherein the process cartridge is inclined with respect to (N).
(N / 2 is an integer part rounded up after the decimal point, N ≧ 7)

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