JP2006039030A - Roller for electrophotography, manufacturing method thereof, and process cartridge and electrophotographic device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller for electrophotography which has a polymer elastic material conductive member less dirtied by most suitably controlling an electrostatic capacity and an electric resistance, and also to provide a manufacturing method thereof, and a process cartridge and an electrophotographic device which have the roller. <P>SOLUTION: The roller for electrophotography having a polymer elastic material layer having hydrophobic groups coupled through isocyanate residues, on a surface thereof, a manufacturing method of the roller for electrophotography, and the process cartridge and an electrophotographic device having the roller for electrophotography are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an elastic member having one or more elastic layers on a support and a method for producing the same. In addition, the present invention relates to a charging member, a developing member, a transfer member, and a process cartridge and an electrophotographic apparatus having those means.

  In an image forming apparatus employing an electrophotographic system, that is, an electrophotographic apparatus, a conductive member is used for various purposes, for example, a member such as a charging member, a developing member, or a transfer member.

  Examples of the shape of the conductive member arranged in contact with or close to the electrophotographic photosensitive member include a roller shape, a blade shape, a brush shape, a belt shape, a film shape, a sheet shape, and a chip shape. (That is, a charging roller, a developing roller, a transfer roller, etc.) are often used.

  The function of the polymer elastic member used for such applications may be hindered by contamination with toner, external additives, paper powder, and the like. For example, in the case of a charging roller, when toner, an external additive, paper powder, or the like adheres to the surface, there is a problem that the charging performance of the portion is deteriorated and the background stain of the image occurs.

  Only the DC voltage is applied to the charging roller consisting of an elastic layer composed of epichlorohydrin rubber and a surface layer composed of fluororesin or silicon resin, and the surface of the photoconductor cleaned by the neutralizing means and cleaning means is uniformly charged. 100 mass parts of an epichlorohydrin rubber solution (solid content: 2.5 wt%) and a solvent-soluble fluororesin solution (solid content: 10.8 wt%) are formed on the elastic layer of the epichlorohydrin rubber. In an image forming apparatus provided with a charging roller in which part by mass and 0.6 part by mass of silica are dissolved in toluene and coated so that the film thickness after drying is 20 μm and a surface layer is formed, From 1K to 5K sheets, clear images with no background stain were obtained, but at the time of 8K sheets, a slight streak-like background stain occurred in the non-image area. . At the time of 10K sheets, the background became quite clear, so when the charging roller was removed from the laser printer, the surface of the charging roller was stained with toner, and the toner was fixed in a streak shape. That is, in the portion where the toner adheres to the surface of the charging roller, the charging performance is deteriorated, and the background stain of the image is generated. However, since the charging roller has a surface layer containing a non-adhesive resin, it is more advantageous for toner adhesion than a charging roller that does not have a surface layer containing a non-adhesive resin. (Toner adhesion is small) However, it is effective to use an abrasive member to remove the toner adhering to the surface (see, for example, Patent Document 1).

  That is, even if a fluororesin layer is provided on the surface of the charging roller, it is difficult to prevent surface contamination with toner, and a complicated configuration such as providing a polishing device is required.

Further, in a charging member in which a semiconductive elastic layer mainly composed of epichlorohydrin rubber is formed on a conductive support, a polymer of fluorine polyol, silicone polyol or the like and polyisocyanate is mainly formed on the semiconductive elastic layer. In the case of a charging member (see, for example, Patent Document 2) characterized in that a surface layer made of the resin is provided, the urethane resin itself has an antifouling effect due to the butadiene chain, fluorine, and siloxane present in the urethane resin. Since there was no antifouling effect, the effect of the entire surface layer was small.
Japanese Patent Laid-Open No. 07-128958, page 8, paragraph numbers [0062] to [0066] JP-A-8-101563, page 3, paragraph numbers [0019] and [0021]

  An object of the present invention is to provide an electrophotographic roller with less contamination, which eliminates the above-mentioned drawbacks, a manufacturing method thereof, a process cartridge and an electrophotographic apparatus having the same.

The roller for electrophotography according to one embodiment of the present invention,
[1] A polymer elastic layer having a hydrophobic group bonded through an isocyanate residue on the surface thereof. Preferred embodiments of the above-described electrophotographic roller include the following electrophotographic rollers [2] to [6].
[2] The roller for electrophotography according to [1], wherein the hydrophobic group is at least one selected from the group consisting of an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a siloxane group, and a fluorinated hydrocarbon group.
[3] The roller for electrophotography according to [2], wherein the aliphatic hydrocarbon group has 3 or more carbon atoms.
[4] The electrophotographic roller according to [2], wherein the siloxane group has a molecular weight of 500 or more.
[5] The roller for electrophotography according to the above [2], wherein the molecular weight of the fluorinated hydrocarbon group is 69 or more.
[6] The electrophotographic roller according to any one of [1] to [5], wherein the electrophotographic roller is a charging roller.

An electrophotographic roller manufacturing method according to another embodiment of the present invention includes [7] a support and a surface-modified polymer elastic body layer on the support. A method for producing a roller for use, comprising the following step (i) and any one of the following steps (ii) and (iii):
(I) preparing a polymer elastic body layer having a first functional group capable of reacting with an isocyanate compound;
(Ii) Applying a first compound having at least one hydrophobic group end and an isocyanate group at the other end on the surface of the elastic polymer layer, and reacting the isocyanate group with the functional group The step of causing;
(Iii) a second compound having a second functional group having at least one end of a hydrophobic group on the surface of the elastic polymer layer and an active hydrogen at the other end, and two or more isocyanates A mixture of a third compound having a group and reacting the first functional group with one of the isocyanate groups of the third compound, and the second functional group of the third compound Reacting with the other isocyanate group, reacting the first functional group with the isocyanate group.

And as a preferable aspect of the manufacturing method of the said roller for electrophotography, what is shown to following [8]-[11] is mentioned.
[8] The method for producing an electrophotographic roller according to the above [7], wherein the step (ii) includes a step of impregnating the compound from the surface of the elastic polymer layer.
[9] The method for producing an electrophotographic roller according to the above [7], wherein the step (iii) includes a step of impregnating the mixture from a surface of the polymer elastic body layer.
[10] The above step (iii) includes the step of impregnating the surface of the polymer elastic layer with a third compound and then applying the second compound to the surface of the polymer elastic layer. ] The manufacturing method of the roller for electrophotography of.
[11] Any of the above [7] to [9], wherein the hydrophobic group is at least one selected from the group consisting of an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a siloxane group, and a fluorinated hydrocarbon group. Method for producing an electrophotographic roller.
[12] The second compound is a monovalent fluorinated alcohol, a monovalent fluorinated amine (primary or secondary amine), a monovalent carbinol-modified siloxane, or a monovalent amino-modified siloxane (primary or secondary). [7] The method for producing a roller for electrophotography according to [7].

Furthermore, an electrophotographic apparatus according to another embodiment of the present invention is
[13] The electrophotographic roller according to any one of [1] to [7] is mounted, and a process cartridge according to another embodiment of the present invention is [14] electronic It is a process cartridge in which a photographic photosensitive member and a charging roller are integrally held and are detachable from the main body of the electrophotographic apparatus, and the charging roller is the electrophotographic roller of [7] above. It is a feature.

  In the present invention, by placing a chemically bonded hydrophobic group on the surface of the electrophotographic roller, the electrostatic capacity and electric resistance are optimally controlled, and an electrophotographic roller with less contamination can be obtained. This is an effect.

The electrophotographic roller according to the present invention is used, for example, in contact with an image carrier, and is used as a member of various uses of an electrophotographic apparatus, for example, a charging member, a developing member, a transfer member, and the like. ing. Hereinafter, a charging roller having a polymer elastic layer made of polyurethane will be described as an example.
As an example of use, the charging roller is placed in contact with the image carrier and connected to a power source to apply a bias to the roller shaft to charge the image carrier to a desired potential.

  As the structure of this charging roller, a conductive polymer elastic body layer made of polyurethane is formed concentrically around the core metal, and the surface of the elastic body layer has, for example, an aliphatic hydrocarbon group or an aromatic hydrocarbon. A compound having at least one terminal selected from a group, a siloxane group, and a fluorinated hydrocarbon group is bonded to the surface via an isocyanate group residue.

  The conductive polyurethane elastic layer is composed of at least one polyol selected from polyether polyol and polyester polyol, a chain extender, a crosslinking agent, an isocyanate, a catalyst, a polyisocyanate and an auxiliary agent commonly used in polyurethane production. It is obtained by mixing and stirring a compound that imparts conductivity and injecting it into a mold. Polyether polyol and polyester polyol may be used in combination.

  The polyether polyol or polyester polyol may be any as long as it can prepare a polyurethane elastic body that forms the elastic layer of the charging roller. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polypropylene glycol-ethylene glycol or blends thereof known as polyalkylene glycol, polytetramethylene ether glycol, copolymer polyol of tetrahydrofuran and alkylene oxide, Various modified products or blends thereof can be exemplified.

  Examples of the polyester polyol include condensed polyester polyols, lactone polyester polyols, polycarbonate polyols or blends thereof obtained by condensation of dicarboxylic acids such as adipic acid and polyols such as ethylene glycol.

  The polyisocyanate may be any one as long as it is commonly used in the preparation of polyurethane elastic bodies. Specific examples of the isocyanate compound include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HDI), and the like. Moreover, the semi prepolymer method which mix | blends some polymeric polyols used for a prepolymer with a hardening | curing agent can also be used.

The isocyanate group content (NCO%) is the mass% of the isocyanate functional group (NCO, molecular weight calculated as 42) contained in 100 g of the prepolymer or semi-prepolymer that is the raw material of the urethane resin. Calculated by the formula:
NCO% = (mass of isocyanate functional group g / 100 g) × 100.

  Specific examples of the chain extender and the crosslinking agent include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, trimethylolpropane and the like.

  In addition, when making high molecular polyol, an isocyanate compound, and a crosslinking agent react, the normal catalyst used for formation of a polyurethane resin may be added. Specific examples of such a catalyst include tertiary amines such as triethylenediamine. Further, quaternary ammonium salts, potassium carboxylates and the like, which are isocyanate trimerization catalysts, can also be used.

  As the compound imparting electrical conductivity, an alkali metal salt, lithium perchlorate, or the like can be used. In addition, complex compounds of perchlorate with polyhydric alcohols can also be used (described in Japanese Patent No. 329846).

  After sufficiently mixing these compounds with a mixing device, an elastic layer can be formed on the surface of the core metal by using a known molding method. For example, in the present invention, the elastic layer can be formed by employing a known one-shot method or prepolymer method.

As a method of covering the surface of the elastic polymer layer of the roller with a hydrophobic group (for example, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a siloxane group, a fluorinated hydrocarbon group, etc.) Examples thereof include the following methods (1) to (3) utilizing the reactivity with the isocyanate group of the urethane bond therein:
(1) A first compound having at least one hydrophobic group terminal and at least one other terminal of an isocyanate group is applied to the surface of the elastic polymer layer, and the isocyanate group of the first compound is applied. Reacting with the active hydrogen of the urethane bond in the polymer elastic layer,
(2) a second compound having a functional group having at least one hydrophobic group terminal and at least one other terminal having active hydrogen on the surface of the elastic polymer layer, and two or more isocyanate groups And applying a mixture of a third compound having the following reaction: reacting one isocyanate group of the third compound with an active hydrogen of a urethane bond; and reacting another isocyanate group of the third compound with the second compound Reacting with a functional group having active hydrogen of
(3) The polymer elastic layer is impregnated with the third compound from the surface, and then the second compound is applied to the surface of the harmful polymer elastic layer to form one isocyanate of the third compound. Reacting a group with an active hydrogen of a urethane bond and reacting another isocyanate group of the third compound with a functional group having an active hydrogen of the second compound;
and so on.

  It is known that an isocyanate group is rich in reactivity, and forms a urethane bond or an allophanate bond in the active hydrogen of a hydroxyl group or a urethane group. In addition, it is known to react with moisture present in the atmosphere or the like to generate a urea bond or a burette bond. In the present invention, the surface of the polymer elastic layer containing these reaction products derived from isocyanate groups has high hardness and high resistance, and an aliphatic hydrocarbon group chemically bonded via a residue of the isocyanate group. Based on the finding that the surface of the elastic layer covered with a hydrophobic group such as an aromatic hydrocarbon group, a siloxane group, or a fluorinated hydrocarbon group can prevent adhesion of toner, external additives, paper powder, etc. It was completed.

According to the method of (1), a compound having at least one hydrophobic group terminal and at least one other terminal being an isocyanate group,
Examples of compounds in which the hydrophobic group is an aliphatic hydrocarbon group or an aromatic hydrocarbon group include propyl isocyanate, butyl isocyanate, hexyl isocyanate, dodecyl isocyanate, octadecyl isocyanate, benzyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, stearoyl isocyanate, etc. Although polyisocyanate etc. can be illustrated, it is not limited to these. Moreover, you may use what mixed these 2 or more types.

What has a hydrophobic group is a siloxane group can be prepared as follows, for example. That is, it can be obtained by reacting a compound having at least one siloxane group terminal and at least one other terminal functional group having active hydrogen with a polyisocyanate having two or more isocyanate groups in an appropriate ratio. Examples of the compound having two isocyanate groups include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), m-phenylene diisocyanate, tetramethylene diisocyanate, Examples include hexamethylene diisocyanate. Further, examples of the compound having three isocyanate groups include 4,4 ′, 4 ″ -triphenylmethane triisocyanate, 2,4 ′, 4 ″ -biphenyltriisocyanate, and 2,4,4 ″ -diphenylmethane triisocyanate. Etc.
Further, as a compound having at least one siloxane group terminal and at least one other terminal functional group having active hydrogen, carbinol-modified siloxane (for example, trade name: X-22-170BX (hydroxyl value = 17.9 mgKOH / g), manufactured by Shin-Etsu Chemical Co., Ltd.) and X-22-170DX (hydroxyl value = 12.7 mgKOH / g), manufactured by Shin-Etsu Chemical Co., Ltd.).

  As a mixing ratio, it is necessary that the isocyanate group remains after the isocyanate group reacts with the functional group having active hydrogen. The number of moles of the polyisocyanate compound is m (NCO) The average functional number of the isocyanate group is f (NCO), the compound has at least one siloxane group terminal, and at least one of the other terminals is a functional group having active hydrogen. The number of moles is m (H), and the average functional number of the active hydrogen-containing compound is f (H). 1 <f (NCO) × m (NCO) / m (H) / f (H) ≦ 5 Is desirable. When f (NCO) × m (NCO) / m (H) -f (H) is 1 or less, a compound having no isocyanate group is formed, and it becomes difficult to bond the roller to the siloxane group. This is because the siloxane component is insufficient and it is difficult to cover the roller surface.

Moreover, since the thing whose hydrophobic group is a fluorinated hydrocarbon group cannot be obtained with a commercial item, it can prepare as follows. That is, it is obtained by reacting a compound having a functional group having at least one fluorinated hydrocarbon terminal and at least one other terminal having an active hydrogen with a polyisocyanate having two or more isocyanate groups in an appropriate ratio. . Examples of the compound having at least one fluorinated hydrocarbon terminal and at least one of the other terminals being a functional group having active hydrogen include compounds represented by the general formula C _m F _{2m + 1} (CH ₂ ) _n OH, formula _{C m F 2m H (CH 2} ) a compound represented by _n OH is used. Examples include tetrafluoropropanol (CF ₂ HCF ₂ CH ₂ OH trade name TFPO, manufactured by Asahi Glass Co., Ltd.) and octafluoropentanol (CF ₂ HCF ₂ CF ₂ CF ₂ CH ₂ OH trade name OFPO, manufactured by Asahi Glass Co., Ltd.). Can do. As a mixing ratio, it is necessary that the isocyanate group remains after the isocyanate group reacts with the functional group having active hydrogen.

  The number of carbon atoms is preferably 3 or more. This is because if it is 2 or less, the urethane bonding group on the urethane surface cannot be covered. If it is 3 or more, the urethane bond on the urethane surface can be sufficiently covered, and contamination of the roller surface can be prevented.

  The number of moles of the polyisocyanate compound is m (NCO), the average functionality of the isocyanate group is f (NCO), the functional group has at least one fluorinated hydrocarbon group terminal, and at least one of the other terminals has an active hydrogen. 1 ≦ f (NCO) × m (NCO) / m (H) / f (H) ≦ 5 where m (H) is the number of moles of a compound and f (H) is the average functionality of the compound having active hydrogen. It is desirable that When f (NCO) × m (NCO) / m (H) -f (H) is 1 or less, a compound having no isocyanate group is formed, and it becomes difficult to bond the roller to the siloxane group. This is because the fluorinated hydrocarbon group component is insufficient and it is difficult to cover the roller surface.

  Specific examples of the method (1) include a method of impregnating the compound in a polymer elastic body layer. More specifically, for example, the surface of the polymer elastic body layer is impregnated by contacting with the liquid containing the compound, and then the compound remaining on the surface is removed by solvent washing or the like and then cured. . Examples of the method for impregnating the polymer elastic body layer by bringing it into contact with the isocyanate treatment liquid include dipping, spray coating, and roll coating. At that time, pressurization is more effective. In the case of immersing the elastic body in this isocyanate, more specific treatment conditions will be described. The temperature of the treatment liquid is preferably from the melting point temperature of the isocyanate used to 100 ° C., particularly set to 40 ° C. to 90 ° C. It is preferable to keep it.

  The immersion time depends on the type of isocyanate, but is within 1 minute, preferably within 30 seconds, and more preferably from 1 second to 10 seconds. If it is this range, it can suppress effectively that a polymeric elastic body layer expand | swells and deform | transforms.

  As a solvent for washing and removing isocyanate remaining on the elastic body surface, it is preferable to use a product solvent of the isocyanate compound. A good solvent for the isocyanate compound such as toluene may be used. In the washing and removal process with such a solvent, the isocyanate compound impregnated in the polymer elastic body layer is diluted or extracted, The density of the isocyanate compound in the polymer elastic layer, and thus the surface hardness of the modified polymer elastic layer may be lowered. By washing and removing with a poor solvent, the isocyanate compound adhering to the surface becomes fine particles and peels off from the surface of the elastic polymer layer, and the isocyanate impregnated in the elastic layer is diluted or extracted. And high-density modification treatment. Examples of the method for fixing and curing the impregnated isocyanate in the elastic layer include methods such as moisture, steam and boiling. Preferably, a method of cooling to a temperature below the freezing point of the isocyanate and then curing with moisture in the atmosphere is preferred.

The modification of the charging roller obtained by this surface treatment is preferably performed within a depth of about 1 mm from the surface, particularly within a depth of about 10 to 500 μm from the surface.
In this way, the surface of the roller can be covered with a hydrophobic group such as an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a siloxane group, or a fluorinated hydrocarbon group.

  On the other hand, when the treated surface is cut and observed with video micro, the impregnated portion appears white. When further expanded, the impregnated isocyanate is scattered in granular form, and the particle size and density of the dispersion change depending on the ratio of the hard segment and the soft segment of the urethane elastic substrate, the impregnation time and temperature, It was found that the particle size and dispersion density can be controlled by setting the conditions.

  In the method (2), the compound to be impregnated is a second compound having a functional group having at least one hydrophobic group terminal and at least one other terminal having an active hydrogen, and two or more isocyanates. The reaction can be carried out in the same manner as in the specific example of the first method except that the mixture with the third compound having a group is used. Specific examples of the second compound having a functional group having at least one hydrophobic group terminal and at least one other terminal having an active hydrogen used in the method (2) and the method (3). As the above-mentioned carbinol-modified siloxane (for example, trade name: X-22-170BX (hydroxyl value = 17.9 mgKOH / g), manufactured by Shin-Etsu Chemical Co., Ltd.) and X-22-170DX (hydroxyl value = 12.7 mgKOH / g) In addition, as the third compound having two or more isocyanate groups, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4 Two isocyanates such as' -diphenylmethane diisocyanate (MDI), m-phenylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate And three isocyanate groups such as 4,4 ', 4 "-triphenylmethane triisocyanate, 2,4', 4" -biphenyl triisocyanate, 2,4,4 "-diphenylmethane triisocyanate, etc. A compound having can be used.

  Next, with respect to the method (3), the surface of the elastic polymer layer is impregnated with a third compound having two or more isocyanate groups, and then has at least one hydrophobic group terminal and at least the other terminal. The surface treatment with the second compound, one of which is a functional group having active hydrogen, is carried out by bringing the surface of the elastic layer into contact with the third compound and impregnating, and then washing the isocyanate remaining on the surface with a solvent. After removal by, for example, contacting the second compound to react one of the isocyanate groups of the third compound with active hydrogen in the urethane bond of the elastic layer, Is reacted with a functional group having active hydrogen of the second compound. Specifically, the same method as described in the above method (1) can be used as a method of impregnating the elastic body layer with the treatment liquid containing the third compound. The same method as described above may be employed for cleaning and removing the third compound remaining on the surface of the elastic layer.

  The same method as described above can also be used for bringing the elastic layer surface impregnated with the third compound into contact with the second compound.

  As a method for fixing the impregnated third compound in the elastic body layer, curing, and further fixing the hydrophobic group to the surface of the elastic body layer through an isocyanate residue of a hydrophobic group by reaction with the second compound, Examples of the method include moisture, steam, and boiling. Preferably, a method of curing an isocyanate group with moisture in the atmosphere under a temperature environment below the freezing point of the isocyanate is preferable. If there is an excess of a compound having at least one hydrophobic group terminal and at least one of the other terminals is a functional group having active hydrogen, and remains without reacting with the polyisocyanate, use a solvent or the like. It is preferable to remove.

  In this way, the surface of the roller can be covered with a hydrophobic group such as an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a siloxane group, or a fluorinated hydrocarbon group.

  On the other hand, when the treated surface is cut and observed with video micro, the impregnated portion appears white. When further expanded, the impregnated isocyanate is scattered in granular form, and the particle size and density of the dispersion change depending on the ratio of the hard segment and the soft segment of the urethane elastic substrate, the impregnation time and temperature, It was found that the particle size and dispersion density can be controlled by setting the conditions.

  In the above description, the polymer elastic body layer is described as an example of polyurethane. However, the present invention is not limited to this, and the polymer elastic body layer may be reactive with an isocyanate group. For example, it is only necessary to have a site having active hydrogen such as an amino group, a hydroxyl group, or a urea bond.

  Other elastic layers include acrylonitrile butadiene rubber (NBR), hydrogenated NBR (H-NBR), NBR copolymerized with a third component such as isoprene, modified NBR introduced with a functional group such as a carboxyl group, and butadiene moiety inside. Nitrile rubbers such as cross-linked NBR, alkyl ether polymers such as ethylene oxide-propylene oxide copolymer, ethylene oxide-propylene oxide-allyl glycidyl ether copolymer, epichlorohydrin rubber (CO), epichlorohydrin-ethylene oxide copolymer rubber (ECO) ), Hydrin rubber such as epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, urethane rubber, chloroprene rubber, chlorosulfonated polyethylene rubber and the like. Among these, in terms of low electrical resistance of the polar polymer itself, hydrin rubber such as CO and ECO, nitrile rubber such as NBR and H-NBR, ethylene oxide-propylene oxide copolymer, ethylene oxide-propylene oxide-allyl glycidyl. Alkyl ether polymers such as ether copolymers, NR (natural rubber), IR (isoprene rubber), BR (butadiene rubber), SBR (styrene butadiene rubber), EPDM (ethylene propylene diene terpolymer), IIR (butyl rubber), Olefin elastomers, SEBS elastomers, polystyrene elastomers and the like are appropriately used.

The elastic body layer of the charging roller of the present invention is 1 × 10 ² Ω to 1 × 10 ⁷ Ω before the surface treatment, and 1 × 10 ⁵ Ω to 1 × 10 ¹⁰ Ω after the surface treatment. It is preferable to adjust the surface average roughness of the elastic layer to 10 μm or less. When the surface of the roller is rough, especially when the average surface roughness of the roller exceeds 10 μm, the toner and the external additive are repeatedly accumulated and discharged, which tends to be easily contaminated. If the resistance is out of the above range, problems such as density unevenness and fogging of the obtained image occur, and a good image cannot be obtained. The charging roller thus obtained charges the surface of the photoconductor, for example, by contacting the surface of the photoconductor. Examples of the photoreceptor include various types of photoreceptors known per se, and an organic photoreceptor is particularly preferable.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
An NCO% of 5. 5 from PPG polyether polyol (trade name: Diol-2000, manufactured by Mitsui Takeda Chemical Co., Ltd.) and 4,4′-diphenylmethane diisocyanate (trade name: Millionate MT, manufactured by Nippon Polyurethane Co., Ltd.) having a number average molecular weight of 2000. A 5% prepolymer was produced. 88 parts by mass of PPG-based polyether polyol having a number average molecular weight of 2000 (trade name: Diol-2000, manufactured by Mitsui Takeda Chemical Co., Ltd.), a mixture of 1,4-butanediol and trimethylolpropane (mass ratio 65:35) 12 Part by mass, urethanization catalyst {potassium acetate (made by Nippon Emulsifier Co., Ltd., trade name P15) and 500 ppm of reactive amine catalyst (made by Japan Emulsifier Co., Ltd., trade name PC17) become 2000 ppm. amount. }, A cross-linking agent in which lithium perchlorate complex compound (complex compound of 3: 7 mass ratio of LiClO ₄ and CH ₃ CH ₂ OCH ₂ CH ₂ OH) was added and mixed and dispersed to make 6.6% of the total Were mixed so that the molar ratio of hydroxyl group / isocyanate group was 0.95, and this mixture was poured into a mold preheated to 130 ° C. where a shaft (φ: 6 mm, l: 255 mm) was previously arranged. , Heated at 130 ° C. for 10 minutes to obtain a φ8.5 mm roller having a conductive polyurethane elastic layer formed on the surface of the shaft excluding both ends. The hardness of this roll was 68 ° (JIS A), and the roller resistance value measured by applying a voltage of 200 V in a 30 ° C./80% RH environment was 4.0 × 10 ⁴ Ω.

<Surface treatment> This roller was immersed in octadecyl isocyanate (trade name: Millionate O, manufactured by Hodogaya Chemical Co., Ltd.) at 80 ° C. for 45 seconds, pulled up, and octadecyl isocyanate remaining on the surface was converted into a naphthenic detergent (a poor solvent). The product was removed by wiping with a sponge soaked in the product name: Actrel 1140L; manufactured by Exxon Chemical. Thereafter, it was immediately left to cool at 25 ° C., and left in an environment of 30 ° C./80% RH for 2 days. The resistance of the electrophotographic roller provided with the elastic polymer layer subjected to the surface modification treatment thus obtained was 6.5 × 10 ⁴ Ω.
-Evaluation of charging uniformity when only DC voltage is applied to the charging roller The above-described electrophotographic roller is mounted as a charging roller on the electrophotographic apparatus having the configuration shown in FIG. 2, in an environment of temperature 30 ° C. and humidity 80% RH. A halftone image was output. The electrophotographic apparatus used in this embodiment has a process speed of 94 mm / s and 30 mm / s. At this time, the image was output by adjusting the applied voltage in each environment so that the surface potential Vd of the electrophotographic photosensitive member 1 was -600V. The image level rank was 2. The results are shown in Table 1.

  As for the image level in the table, rank 1 is very good, rank 2 is good, rank 3 has a slight streak and spot image defect, and rank 4 has a streak and spot image defect. Is the level.

  Further, when copying was continued under the same conditions, good images were obtained up to 30,000 sheets at A4.

[Comparative Example 1]
In the surface treatment of Example 1, the conductive roller was immersed in 80 ° C. 4,4′-diphenylmethane diisocyanate (trade name: Millionate MT, manufactured by Nippon Polyurethane) instead of being immersed in octadecyl isocyanate at 80 ° C. for 45 seconds. After dipping for 2 seconds, excess 4,4′-diphenylmethane diisocyanate was removed by wiping with a sponge soaked with 1140 L of actrel. Thereafter, it was quickly cooled to 25 ° C. and left in a 30 ° C./80% RH environment for 2 days. Others were performed similarly.

The resistance of the obtained surface treatment roller was 5.9 × 10 ⁴ Ω.
The image level rank was 2.

  Further, when copying was continued under the same conditions, good images were obtained up to 20,000 sheets at A4.

  After that, however, vertical streaks appeared in the image, and when the roller was removed and observed, it was found that the toner and external additives were streaked on the roller surface, which resulted in image defects. did.

[Example 2]
Carbinol-modified siloxane (product name X-22-170DX, hydroxyl value = 12.7 mgKOH / g [molecular weight is about approx. Molecular weight) 25 g (0.1 mol, functional number 2) of 4,4'-diphenylmethane diisocyanate at 80 ° C under nitrogen atmosphere 2327] (manufactured by Shin-Etsu Chemical Co., Ltd.) 442 g (0.1 mol, functional number 1, molecular weight of siloxane group is about 2200) was slowly added dropwise with stirring, then allowed to stand at 80 ° C. for 6 hours and cooled to room temperature. f (NCO) × m (NCO) / m (H) −f (H) = 1. An opalescent liquid having an isocyanate content of 18% was obtained.

In the surface treatment of Example 1, instead of immersing the roller in 80 ° C. octadecyl isocyanate for 45 seconds, the conductive roller was immersed in the 80 ° C. isocyanate liquid for 60 seconds, then pulled up, and then remained on the surface. The liquid was removed by wiping with a sponge soaked with Actorel 1140L (exxon), which is a poor solvent. Thereafter, it was immediately left to cool at 25 ° C., and left in an environment of 30 ° C./80% RH for 2 days. The resistance of the obtained electrophotographic roller was 7.4 × 10 ⁴ Ω (30 ° C./80% RH). The subsequent experiments and evaluations were performed in the same manner as in Example 1. As a result, the image level was 1. Furthermore, when copying was continued under the same conditions, good images were obtained up to 35000 sheets at A4.

[Example 3]
Under a nitrogen atmosphere at 80 ° C., 50 mg of a urethanization catalyst (trade name NC-IM, manufactured by Nippon Emulsifier Co., Ltd.) is added to 250 g (1 mol, functional number 2) of 4,4′-diphenylmethane diisocyanate, and octafluoropentanol ( 232 g (1 mol, functional number 1) (product name OFPO, molecular weight = 232, manufactured by Asahi Glass Co., Ltd.) was slowly added dropwise with stirring, then allowed to stand at 80 ° C. for 6 hours and cooled to room temperature. f (NCO) × m (NCO) / m (H) −f (H) = 1. An opalescent liquid having an isocyanate content of 17% was obtained.

In the surface treatment of Example 1, instead of immersing the conductive roller in 80 ° C. octadecyl isocyanate for 45 seconds, the conductive roller was immersed in the 80 ° C. isocyanate liquid for 60 seconds, then pulled up, and then applied to the surface. The remaining liquid was removed by wiping with a sponge soaked with Actrel 1140L. Thereafter, it was immediately left to cool at 25 ° C., and left in an environment of 30 ° C./80% RH for 2 days. The resistance of the obtained surface treatment roller was 7.0 × 10 ⁴ Ω (30 ° C./80% RH). Others were performed similarly.

  The image level was 1. Further, when copying was continued under the same conditions, good images were obtained up to 30000 sheets with A4.

[Example 4]
In the surface treatment of Example 1, instead of immersing the conductive roller in 80 deg. Immerse for 2 seconds, then immerse in 80 ° C. octafluoropentanol to which 50 mg of urethanization catalyst (Nippon Emulsifier Co., Ltd., trade name NC-IM) is added for 3 minutes, pull it up, and then immediately leave it to cool at 25 ° C. And left in an environment of 30 ° C./80% RH for 2 days. The resistance of the obtained surface treatment roller was 6.9 × 10 ⁴ Ω. Others were performed similarly.

  The image level was 1. Furthermore, when copying continued under the same conditions. Good images were obtained up to 30000 sheets at A4.

It is the schematic which shows an example of the roller for electrophotography of this invention. It is a schematic block diagram which shows an example of the electrophotographic apparatus of this invention.

Explanation of symbols

1 Electrophotographic photoreceptor 2 Charging member (charging roller)
2a Support (conductive support)
2b Elastic layer 2c Resistive layer 2d Surface 3 Image exposure means 4 Developing means 4a Toner carrier 4b Stirring member 4c Toner regulating member 5 Transfer means 6 Cleaning means L Laser light S1, S2, S3 Bias applied power supply P Transfer material

Claims (14)

  An electrophotographic roller comprising a polymer elastic body layer having a hydrophobic group bonded through an isocyanate residue on its surface.   2. The electrophotographic roller according to claim 1, wherein the hydrophobic group is at least one selected from the group consisting of an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a siloxane group, and a fluorinated hydrocarbon group.   The roller for electrophotography according to claim 2, wherein the aliphatic hydrocarbon group has 3 or more carbon atoms.   The roller for electrophotography according to claim 2, wherein the siloxane group has a molecular weight of 500 or more.   The roller for electrophotography according to claim 2, wherein the molecular weight of the fluorinated hydrocarbon group is 69 or more.   The electrophotographic roller according to claim 1, wherein the electrophotographic roller is a charging roller. An electrophotographic roller manufacturing method comprising: a support; and a modified polymer elastic body layer on the support, wherein the following process ( i) and any one of the following steps (ii) and (iii): A method for producing an electrophotographic roller, comprising:
(I) preparing a polymer elastic body layer having a first functional group capable of reacting with an isocyanate compound;
(Ii) Applying a first compound having at least one hydrophobic group end and an isocyanate group at the other end on the surface of the elastic polymer layer, and reacting the isocyanate group with the functional group The step of causing;
(Iii) a second compound having a second functional group having at least one hydrophobic group terminal on the surface of the polymer elastic body layer and having an active hydrogen at the other terminal, and two or more isocyanates And applying a third compound having a group to react the first functional group with one of the isocyanate groups of the third compound, and to react the second functional group with the isocyanate group of the third compound. A step of reacting the other functional group with the other, and a step of reacting the first functional group with the isocyanate group.   The method for producing an electrophotographic roller according to claim 7, wherein the step (ii) includes a step of impregnating the compound from the surface of the elastic polymer layer.   The method for producing an electrophotographic roller according to claim 7, wherein the step (iii) includes a step of impregnating a mixture of the second compound and the third compound from the surface of the polymer elastic body layer. .   The electron according to claim 7, wherein the step (iii) includes a step of impregnating a surface of the polymer elastic layer with a third compound and then applying the second compound to the surface of the polymer elastic layer. A method for producing a photographic roller. The hydrophobic group is
The method for producing an electrophotographic roller according to any one of claims 7 to 9, which is at least one selected from the group consisting of an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a siloxane group, and a fluorinated hydrocarbon group.   The second compound is a monovalent fluorinated alcohol or a monovalent fluorinated amine (primary or secondary amine) or a monovalent carbinol-modified siloxane or a monovalent amino-modified siloxane (primary or secondary amine). A method for producing a roller for electrophotography according to claim 7. An electrophotographic apparatus, comprising the electrophotographic roller according to claim 1.   A process cartridge in which an electrophotographic photosensitive member and a charging roller are integrally held, and are configured to be detachable from an electrophotographic apparatus main body, wherein the charging roller is an electron according to any one of claims 1 to 6. An electrophotographic apparatus characterized by being a photographic roller.

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