JP4170176B2 - Charging member and image forming apparatus having the same - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member for a proximity charging system that performs a charging process on a photoreceptor in an image forming apparatus such as an electrophotographic copying machine, a laser printer, and a facsimile, and an image forming apparatus having the charging member.

  A conductive contact member (see Patent Document 1) in which a thermosetting urethane contains a radical chain-inhibited antioxidant and an inorganic ionic conductivity imparting agent has been proposed. In a charging device using a contact charging method using a conductive contact member, the antioxidant and inorganic ionic conductivity imparting agent constituting the conductive charge member adhere to the photoreceptor, and the photoreceptor is stopped for a long time. There was a problem of permanent deformation of the conductive charging member that sometimes occurred.

  There has been proposed a charging device (see Patent Document 2) that includes an antioxidant and a contact charging member that is charged in contact with the photosensitive member and a non-contact charging member that is charged without contacting the photosensitive member. However, in such a charging device, in the contact charging member, the antioxidant constituting the charging member adheres to the photosensitive member, and the anti-participation agent generated when the photosensitive member is stopped for a long time is applied to the photosensitive member. There are problems such as adhesion, permanent deformation of the contact charging member that occurs when the photoreceptor is stopped for a long time, and non-contact charging members generate a reactive gas such as ozone and deteriorate the surface of the photoreceptor. there were.

  A charging member (see Patent Document 3) that uses a high molecular weight ion conductive material having a quaternary ammonium base and has little bleed-out over time has been proposed. In a charging member using a high molecular weight ion conductive material, the resistance value is highly dependent on the temperature and humidity environment, so depending on the addition ratio of the ion conductive material, the problem of abnormal discharge due to low resistance, high resistance There are problems of poor charging due to, and prescription is difficult.

  In a conventional image forming apparatus such as an electrophotographic copying machine, a laser printer, and a facsimile, a charging roller is generally used as a charging member that performs a charging process on a photosensitive member. FIG. 2 is an explanatory diagram of an image forming apparatus having a conventional charging roller.

  In FIG. 2, reference numeral 111 denotes a conventional charging roller type image forming apparatus. A conventional charging roller type image forming apparatus 111 includes a photosensitive drum 101 on which an electrostatic latent image is formed, a charging roller 102 that performs charging processing in contact with the photosensitive drum 101, an exposure unit 103 such as a laser beam, and a photosensitive member. A developing roller 104 for attaching toner to the electrostatic latent image on the photosensitive drum 101, a power pack 105 for applying a DC voltage to the charging roller 102, and a transfer roller for transferring the toner image on the photosensitive drum 101 to the recording paper 107. 106, a cleaning device 108 for cleaning the photosensitive drum 101 after the transfer process, and a surface potential meter 109 for measuring the surface potential of the photosensitive drum 101. In FIG. 2, functional units normally required in other electrophotographic processes are omitted because they are not required in this specification.

  Next, a basic image forming operation in the conventional charging roller type image forming apparatus 111 will be described.

When a DC voltage is supplied from the power pack 105 to the charging roller 102 in contact with the photosensitive drum 101, the surface of the photosensitive drum 101 is uniformly charged at a high potential. Immediately thereafter, when image light is irradiated onto the surface of the photosensitive drum 101 by the exposure unit 103, the potential of the irradiated portion of the photosensitive drum 101 is lowered. It is known that such a charging mechanism to the surface of the photosensitive drum 101 by the charging roller 102 is a discharge according to Paschen's law in a minute space between the charging roller 102 and the photosensitive drum 101.

  Since the image light has a light amount distribution according to white / black of the image, when the image light is irradiated, the potential distribution corresponding to the recorded image on the surface of the photosensitive drum 101 by the irradiation of the image light, that is, An electrostatic latent image is formed. When the portion of the photosensitive drum 101 on which the electrostatic latent image is formed in this way passes through the developing roller 104, toner adheres according to the level of the potential, and a toner image that visualizes the electrostatic image is formed. Is done. The recording paper 107 is conveyed by a registration roller (not shown) at a predetermined timing to the portion of the photosensitive drum 101 where the toner image is formed, and overlaps the toner image. Then, after the toner image is transferred onto the recording paper by the transfer roller 106, the recording paper 107 is separated from the photosensitive drum 101. The separated recording paper 107 is conveyed through a conveyance path, heated and fixed by a fixing unit (not shown), and then discharged outside the apparatus. When the transfer is completed in this manner, the surface of the photosensitive drum 101 is cleaned by the cleaning device 108, and the residual charge is removed by a quenching lamp (not shown), so that the next image forming process is performed. Prepared for.

As a charging method using a charging roller, a contact charging method in which a roller is brought into contact with a photosensitive member is generally used.
(1) The substance constituting the charging roller oozes out from the charging roller, and this adheres to the surface of the object to be charged and leaves a charging roller mark.
(2) When an AC voltage is applied to the charging roller, the charging roller that is in contact with the member to be charged vibrates, so that a charging noise is generated.
(3) Since the toner on the photosensitive member adheres to the charging roller (particularly, the above-described oozing causes toner adhesion more easily), so that the charging performance of the charging roller is reduced,
(4) the substance constituting the charging roller adheres to the photoreceptor, and
(5) The charging roller is permanently deformed when the photosensitive member is stopped for a long time.
There was a problem.

  As a technique for solving such a problem, a proximity charging method (see Patent Document 1) in which a charging roller is brought close to a photosensitive member has been proposed. In this proximity charging method, the photosensitive member is charged by applying a voltage to the charging roller with the charging roller facing the photosensitive member at a closest distance (0.005 to 0.3 mm). Charging method. In this proximity charging method, the roller and the photosensitive member are not in contact with each other, which has been a problem in the conventional contact charging method, (a) the substance constituting the charging roller adheres to the photosensitive member, and (B) There is no problem that the photoreceptor is permanently deformed when stopped for a long time. In this proximity charging method, the amount of toner that adheres to the charging roller is reduced, so that the toner on the photosensitive member is less likely to adhere to the charging roller, and the charging performance of the charging roller does not deteriorate.

  The required characteristics of the charging roller used in the proximity charging method are different from those of the charging roller used in the conventional contact charging method. A charging roller generally used in the contact charging system has a structure in which an elastic body such as vulcanized rubber is coated around a cored bar. Therefore, in the contact charging method, the photosensitive member is uniformly charged, so that it is necessary that the charging roller uniformly contacts the photosensitive member.

When using a charging roller formed of an elastic material such as vulcanized rubber in the proximity charging method,
(1) Since a gap is formed between the photosensitive member and the charging roller, it is necessary to interpose a gap holding member such as a spacer in the non-image area at both ends of the charging roller, but the charging roller formed of an elastic body Then, since it is difficult to make the gap uniform due to deformation of the elastic body, fluctuations in the charging potential and image unevenness due to it, and
(2) The vulcanized rubber material constituting the elastic body is likely to sag and deform over time, so that the gap also varies over time.
There was a problem.

In order to solve such a problem, it is conceivable to use a thermoplastic resin which is an inelastic body. As a result, the gap between the photoconductor and the charging roller can be made uniform. It is known that the charging mechanism on the surface of the photosensitive drum by the charging roller is a discharge according to Paschen's law in a minute discharge between the charging roller and the photosensitive drum. In order to obtain the function of holding the photosensitive drum at a predetermined charging potential, it is necessary to control the electric resistance value of the thermoplastic resin to a semiconductive region (about 10 ⁶ to 10 ⁹ Ωcm).

  As a method of controlling the electrical resistance value, there is a method of dispersing a conductive pigment such as carbon black in a thermoplastic resin. However, when an attempt is made to set the electrical resistance adjustment layer in the semiconductive region using a conductive pigment, since the variation in electrical resistance value increases, partial charging failure occurs, and as a result, image defects occur. There was a problem.

  On the other hand, as another means for controlling the electric resistance value, there is a method using an ion conductive material, that is, an electrolyte salt such as a Li salt. Since the ion conductive material is dispersed at the molecular level in the matrix resin, the electric resistance value variation is small compared to the above-mentioned one in which the conductive pigment is dispersed. It did not matter. However, since the electrolyte salt has a low molecular weight, it tends to bleed out on the surface of the matrix resin. For this reason, when the bleed out to the surface of the charging roller, toner sticking occurs and image defects occur. There was a problem of letting.

  Therefore, in order to avoid bleed out, it is conceivable to use a high molecular weight ion conductive material. In this case, the ion conductive material is dispersed and fixed in the matrix resin, and bleed out to the surface hardly occurs. .

However, the polymer composite is decomposed by reacting with oxygen molecules in a process called autooxidation. Auto-oxidation is an addition reaction of oxygen to a polymer radical (R.). This reaction and the regeneration of P. by hydrogen abstraction of the generated peroxy radical (ROO.), As well as the oxy radical from hydroperoxide (ROOH). The formation process of (RO.) And peroxy radicals is the center of the decomposition reaction. Decomposition proceeds as a chain reaction once free radicals are generated due to various factors such as heat, oxygen, and mechanical shear force during processing and use. Due to this deterioration process, the physical properties of the resin material are deteriorated, the compatibility between the constituent resins is deteriorated, the strength of the weld portion generated at the time of molding is lowered, and the electric resistance value is fluctuated. When the strength is reduced in this way, when a resin with low mechanical strength or poor compatibility is used as the matrix resin, resistance adjustment is performed due to electrical and mechanical stress during use and volume fluctuations over time and the environment. There was a problem that cracks occurred in the weld portion of the layer. In addition, there is a problem that the resistance variation in the weld portion causes a defect of partial image defect.
JP-A-11-30897 JP 2003-107853 A Japanese Patent Application Laid-Open No. 7-121009 Japanese Patent Laid-Open No. 3-240076

  The present invention aims to solve this problem.

  That is, the present invention prevents variations in electrical resistance, toner adhesion and charging failure associated therewith, as well as excellent environmental stability, and prevents a decrease in strength of the weld portion and fluctuation in resistance due to oxidative degradation. It is an object of the present invention to provide a charging member that can be used, and an image forming apparatus having the charging member.

  In order to achieve the above object, the invention described in claim 1 includes an electric resistance adjusting layer formed on the conductive support and a protective layer coated on the surface of the electric resistance adjusting layer. In the charging member, the electric resistance adjusting layer includes (A) a styrene thermoplastic resin, (B) a polymer type ion conductive material, and (C) a phenolic antioxidant, a phosphorus processing heat stabilizer, and a lactone system. A charging member comprising a resin composition obtained by melting and kneading a heat-resistant stabilizer composed of a processing heat stabilizer.

  The invention described in claim 2 is characterized in that the polymer type ion conductive material is a polyether ester amide-containing compound.

  The invention described in claim 3 is the invention described in claim 1 or 2, wherein the blending ratio of the resin composition is (A) 30 to 70% by weight and (B) 70 to 30% by weight. And the compounding quantity of (C) is 0.01-0.5 weight part with respect to a total of 100 weight part of (A) and (B), It is characterized by the above-mentioned.

  The invention described in claim 4 is the invention described in any one of claims 1 to 3, wherein the blending ratio of each component contained in (C) is 30 to 60% by weight of a phenolic antioxidant. The phosphorus processing heat stabilizer is 40 to 70% by weight, and the lactone processing heat stabilizer is 1 to 30% by weight.

  The invention described in claim 5 is the invention described in any one of claims 1 to 4, wherein the protective layer is an acrylic silicon resin, a fluororesin, a silicone resin, an acrylic resin, a polyamide resin, a polyurethane resin, a polyester. It is comprised by resin chosen from resin and polyvinyl butyral resin.

  According to a sixth aspect of the present invention, there is provided a process cartridge characterized in that the charging member according to any of the first to fifth aspects of the present invention is used by being disposed close to a member to be charged.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising the process cartridge according to the sixth aspect.

  (1) According to the invention described in claim 1, the electrical resistance adjusting layer comprises (A) a styrene-based thermoplastic resin, (B) a polymer ion conductive material, and (C) a phenol-based antioxidant. , A heat-resistant stabilizer composed of a phosphorus-based processing heat stabilizer and a lactone-based processing heat stabilizer, which is melt-kneaded to prevent variation in electrical resistance, toner fixation, and associated charging failure In addition, it is possible to provide a charging member that is excellent in environmental stability and that can prevent a decrease in the strength of the weld portion and a variation in resistance value due to oxidative degradation.

  (2) According to the invention described in claim 2, since the polymer ion conductive material is a polyether ester amide-containing compound, it is uniformly dispersed and immobilized at the molecular level in the matrix polymer. There is no variation in electrical resistance value due to poor dispersion of the conductive pigment as seen in the resin composition in which the conductive pigment is dispersed, and bleed-out hardly occurs.

  (3) According to the invention described in claim 3, the compounding ratio of the resin composition constituting the electric resistance adjusting layer is (A) 30 to 70% by weight and (B) 70 to 30% by weight. And since the compounding quantity of (C) is 0.01-0.5 weight part with respect to a total of 100 weight part of (A) and (B), resin which comprises an electrical resistance adjustment layer The reactivity required for preventing deterioration of the composition can be easily obtained, and therefore, side effects due to the heat stabilizer of the resin composition can be prevented.

  (4) According to the invention described in claim 4, the compounding ratio of each component contained in (C) in the resin composition constituting the electric resistance adjusting layer is 30 to 60% by weight of the phenolic antioxidant. Since the phosphorus processing heat stabilizer is 40 to 70% by weight and the lactone processing heat stabilizer is 1 to 30% by weight, excellent processing stability can be obtained in the resin composition.

  (5) According to the invention described in claim 5, the protective layer is a resin selected from an acrylic silicon resin, a fluorine resin, a silicone resin, an acrylic resin, a polyamide resin, a polyurethane resin, a polyester resin, and a polyvinyl butyral resin. Since it is constituted, a charging member excellent in toner fixing property can be obtained.

  (6) According to the invention described in claims 6 and 7, a process is provided in which the charging member (roller) 10 according to any one of claims 1 to 5 is disposed in contact with the member to be charged. Having a cartridge prevents variations in electrical resistance, toner sticking, and charging defects associated therewith, as well as excellent environmental stability, as well as a decrease in strength and resistance of the weld due to oxidative degradation. Thus, an image forming apparatus capable of preventing the occurrence of image defects by preventing the fluctuation of the image forming apparatus can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a sectional view of a charging roller showing an embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes a charging member (charging roller). The charging member (charging roller) 10 includes an electric resistance adjusting layer 2 formed on the conductive support 1 and a protective layer 3 covered on the surface of the electric resistance adjusting layer 2. The electrical resistance adjusting layer 2 includes (A) a styrene-based thermoplastic resin, (B) a polymer ion conductive material, and (C) a phenol-based antioxidant, a phosphorus-based processing heat stabilizer, and a lactone-based processing. It is comprised with the resin composition which melt-kneaded the heat-resistant stabilizer which consists of a heat stabilizer.

  Thus, the electrical resistance adjusting layer 2 is composed of (A) a styrenic thermoplastic resin, (B) a polymer type ion conductive material, and (C) a phenolic antioxidant, a phosphorus processing heat stabilizer and a lactone. When it is composed of a resin composition obtained by melting and kneading a heat-resistant stabilizer composed of a system processing heat stabilizer, it prevents variation in electrical resistance, toner fixation and charging failure associated therewith, and excellent environmental stability. In addition, it is possible to provide a charging member that can prevent a decrease in strength of the weld portion and a change in resistance value due to oxidation degradation.

（式中、Ｒ¹ ，Ｒ² ，Ｒ³ は、炭素数が１〜２０のアルキル基である。）
で示される共重合体であって、ポリアミド単位のハード部分とポリエーテル単位のソフト部分からなるものであるが、それ自体は、公知の樹脂である。そして、前記ポリエーテルエステルアミドは、イオン導電性の高分子材料であるので、マトリクスポリマー中に分子レベルで均一に分散、固定化され、そのために、導電性顔料を分散した樹脂組成物にみられるような導電性顔料の分散不良に伴う電気抵抗値のバラツキが生じない。また、前記ポリエーテルエステルアミドは、高分子材料であるので、ブリードアウトが生じ難い。 The polymer ion conductive material (B) is preferably a polyether ester amide. Such polyetheresteramides have the formula

(In the formula, R ¹ , R ² and R ³ are alkyl groups having 1 to 20 carbon atoms.)
The copolymer is a copolymer composed of a hard part of a polyamide unit and a soft part of a polyether unit, and is a known resin per se. Since the polyether ester amide is an ion conductive polymer material, it is uniformly dispersed and fixed at the molecular level in the matrix polymer. Therefore, it can be found in a resin composition in which a conductive pigment is dispersed. There is no variation in electrical resistance value due to such poor dispersion of the conductive pigment. In addition, since the polyether ester amide is a polymer material, bleeding out hardly occurs.

  In the present invention, the blending ratio of the resin composition is preferably (A) 30 to 70% by weight and (B) 70 to 30% by weight, and the blending amount of (C) is: It is 0.01-0.5 weight part with respect to a total of 100 weight part of (A) and (B). Thus, the blending ratio of the resin composition is (A) 30 to 70% by weight and (B) 70 to 30% by weight, and the blending amount of (C) is (A) and The reactivity required for prevention of deterioration of the resin composition constituting the electric resistance adjusting layer 2 can be easily obtained when the content is 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the total of (B). Therefore, side effects due to the heat stabilizer of the resin composition can be prevented.

  In the present invention, the blending ratio of each component contained in (C) is preferably 30 to 60% by weight of a phenolic antioxidant, 40 to 70% by weight of a phosphorus processing heat stabilizer, and a lactone system. The processing heat stabilizer is 1 to 30% by weight. Thus, the blending ratio of each component contained in (C) is 30 to 60% by weight of the phenolic antioxidant, 40 to 70% by weight of the phosphorus processing heat stabilizer, and the lactone processing heat stabilizer. The process stability which was excellent in the resin composition which comprises the electrical resistance adjustment layer 2 as it is 1 to 30 weight% can be obtained.

  In the present invention, the resin composition is obtained by melt-kneading the mixture of (A), (B) and (C) with a biaxial kneader, a kneader or the like. The electrical resistance adjusting layer 2 in the present invention is formed by coating the surface of the conductive support 1 with the thermoplastic resin composition thus obtained by means such as extrusion molding or injection molding. Further, the electrical resistance adjusting layer 2 formed in this way is subjected to cutting and / or grinding processing at a desired stage to obtain a desired surface accuracy.

  In the present invention, the protective layer is preferably made of a resin selected from an acrylic silicon resin, a fluororesin, a silicone resin, an acrylic resin, a polyamide resin, a polyurethane resin, a polyester resin, and a polyvinyl butyral resin. Since these resins are excellent in non-adhesiveness, a charging member excellent in toner fixing property can be obtained.

  Further, since such a resin is electrically insulating, if the protective layer 3 is formed alone, the characteristics as a charging roller cannot be obtained. Therefore, in the present invention, the resin composition forming the protective layer 3 contains conductive particles. As such conductive particles, for example, metal oxides such as tin oxide and iron oxide, and carbon black such as acetylene black and ketjen black are preferably used. Other conductive particles may be used.

Thus, when the resin composition forming the protective layer 3 contains conductive particles, the electrical resistance value of the protective layer 3 can be easily adjusted. The electric resistance value of the protective layer 3 is preferably adjusted to be larger than that of the electric resistance adjusting layer 2. If the electrical resistance value of the protective layer 3 is adjusted to be larger than that of the electrical resistance adjustment layer 2, voltage concentration and abnormal discharge (leakage) on the photosensitive member defect portion can be avoided. it can. However, if the electrical resistance value of the protective layer 3 is too high, charging efficiency is lowered. Therefore, the difference in electrical resistance value between the protective layer 3 and the electrical resistance adjustment layer 2 may be 10 ³ Ωcm or less. preferable.

  The protective layer 3 is formed on the electric resistance adjusting layer 2 by dispersing the resin material constituting the protective layer 3 in an organic solvent to prepare a paint, which is then coated by means such as spray coating or dipping. Do.

  In the process cartridge of the present invention (see 110 in FIG. 2), the charging member (roller) 10 according to any one of claims 1 to 5 is provided so as to be disposed in contact with a member to be charged. . The image forming apparatus of the present invention includes the process cartridge. As described above, if the charging member (roller) 10 according to any one of claims 1 to 5 has the process cartridge provided so as to be disposed in contact with the member to be charged, the electric resistance value varies. In addition to preventing toner fixation and charging failure associated therewith, it has excellent environmental stability, and also prevents the occurrence of image defects by preventing a decrease in the strength of the weld and the change in resistance value due to oxidative degradation. The image forming apparatus can perform the above.

  In the present embodiment, the charging roller in which the charging member 10 is embodied has been described. However, the charging member 10 in the present invention may be a charging member other than the charging roller, such as a blade, as long as it does not contradict the purpose of the present invention. It doesn't matter if it's something.

(Example 1)
(A) ABS resin (GR-0500, manufactured by Denki Kagaku Kogyo) 50% by weight, (B) Polyetheresteramide (IRGASTAT P18, manufactured by Ciba Specialty Chemicals) 50% by weight, and (C) Phenol-based oxidation 0.1 parts by weight of heat stabilizer (IRGASTAT HP 2225 / FF, manufactured by Ciba Specialty Chemicals Co., Ltd.) consisting of an inhibitor, a phosphorus processing heat stabilizer and a lactone processing heat stabilizer (materials of (A) and (B) above) 0.1 parts by weight with respect to a total of 100 parts by weight) to obtain a resin composition, and this resin composition is coated on a core shaft made of stainless steel with a diameter of 8 mm by injection molding to form an electric resistance adjusting layer. did. Next, a resin composition comprising an acrylic silicon resin (3000 VH-P, manufactured by Kawakami Paint Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight based on the total solid content) on the surface of the electric resistance adjusting layer. Was applied to form a protective layer having a thickness of about 10 μm to obtain a charging roller having a diameter of 12 mm.

(Example 2)
From the surface of the electrical resistance adjusting layer formed in the same manner as in Example 1, from a fluororesin (Lumiflon LF-600, manufactured by Asahi Glass Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight based on the total solid content) A charging roller having a diameter of 12 mm was obtained by applying the resin composition to form a protective layer having a thickness of about 10 μm.

(Example 3)
Resin composition comprising polyamide resin (Daiamide T-171, manufactured by Daicel Huls) and carbon black (10% by weight based on the total solid content) on the surface of the electric resistance adjusting layer formed in the same manner as in Example 1. A charging roller having a diameter of 12 mm was obtained by applying the product to form a protective layer having a thickness of about 10 μm.

Example 4
On the surface of the electrical resistance adjusting layer formed in the same manner as in Example 1, polyvinyl butyral resin (Denka Butyral 3000-K, manufactured by Denki Kagaku Kogyo Co., Ltd.), isocyanate curing agent, and tin oxide (60% based on the total solid content) A charging roller having a diameter of 12 mm was obtained by applying a resin composition comprising (weight%) to form a protective layer having a thickness of about 10 μm.

(Example 5)
(A) HI-PS resin (H450, manufactured by Toyo Styrene Co., Ltd.) 50% by weight, (B) polyether ester amide (IRGASTAT P18, manufactured by Ciba Specialty Chemicals Co., Ltd.) 50% by weight, and (C) phenolic oxidation 0.2 parts by weight of heat stabilizer (IRGASTAT HP 2225 / FF, manufactured by Ciba Specialty Chemicals) consisting of an inhibitor, a phosphorus processing heat stabilizer and a lactone processing heat stabilizer (materials of (A) and (B) above) 0.2 parts by weight with respect to a total of 100 parts by weight) to obtain a resin composition, and this resin composition is coated on a core shaft made of stainless steel with a diameter of 8 mm by injection molding to form an electric resistance adjusting layer. did. Next, a resin composition comprising a fluororesin (Lumiflon LF-600, manufactured by Asahi Glass Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight based on the total solid content) is formed on the surface of the electric resistance adjusting layer. The charging roller was applied to form a protective layer having a thickness of about 10 μm to obtain a charging roller having a diameter of 12 mm.

(Comparative Example 1)
40 parts by weight of ABS resin (GR-1500, manufactured by Denki Kagaku Kogyo Co., Ltd.) and 60 parts by weight of ion conductive polymer compound containing quaternary ammonium base (Roleex AS-1720, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) The resin composition was blended into a resin composition, and the resin composition was coated on a core shaft made of stainless steel with a diameter of 10 mm by injection molding to form an electric resistance adjusting layer. Next, a resin composition comprising an acrylic silicon resin (3000 VH-P, manufactured by Kawakami Paint Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight based on the total solid content) on the surface of the electric resistance adjusting layer. Was applied to form a protective layer having a thickness of about 10 μm to obtain a charging roller having a diameter of 12 mm.

(Comparative Example 2)
40 parts by weight of a polypropylene resin (MA2, manufactured by Nippon Polychem) and 60 parts by weight of an ion conductive polymer compound (ROLEX AS-1720, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) containing a quaternary ammonium base Then, a resin composition was prepared, and this resin composition was coated on a core shaft made of stainless steel with a diameter of 10 mm by injection molding to form an electric resistance adjusting layer. Next, a resin composition comprising a fluororesin (Lumiflon LF-600, manufactured by Asahi Glass Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight based on the total solid content) is applied to the surface of the electrical resistance adjusting layer. Thus, a charging roller having a diameter of 12 mm was obtained by forming a protective layer having a thickness of about 10 μm.

(Comparative Example 3)
A rubber composition in which 5 parts by weight of ammonium perchlorate is blended with 100 parts by weight of epichlorohydrin rubber (Epichromer CG, manufactured by Daiso Co., Ltd.) by extrusion molding on a 10 mm diameter core shaft made of stainless steel, is vulcanized. Then, an electric resistance adjusting layer was formed. Next, the surface of the electric resistance adjusting layer is made of polyvinyl butyral resin (Denka Butyral 3000-K, manufactured by Denki Kagaku Kogyo Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight based on the total solid content). By applying the resin composition to form a protective layer having a thickness of about 10 μm, a charging roller having a diameter of 12 mm was obtained.

(Comparative Example 4)
100 parts by weight of ABS resin (GR-1500, manufactured by Denki Kagaku Kogyo Co., Ltd.) and 20 parts by weight of conductive carbon black (Ketjen Black EC, manufactured by Ketjen Black International) are blended to form a resin composition. The composition was coated on a core shaft made of stainless steel having a diameter of 10 mm by injection molding to form an electric resistance adjusting layer. Next, a resin composition comprising a polyamide resin (Daiamide T-171, manufactured by Daicel Huls Co., Ltd.) and carbon black (10% by weight with respect to the total solid content) is applied to the surface of the electrical resistance adjusting layer. A charging roller having a diameter of 12 mm was obtained by forming a protective layer having a thickness of about 10 μm.

(Comparative Example 5)
100 parts by weight of ABS resin (GR-1500, manufactured by Denki Kagaku Kogyo Co., Ltd.) and 5 parts by weight of lithium perchlorate are blended to form a resin composition, and this resin composition is injected onto a 10 mm diameter core shaft made of stainless steel. An electric resistance adjusting layer was formed by coating. Next, the surface of the electric resistance adjusting layer is made of polyvinyl butyral resin (Denka Butyral 3000-K, manufactured by Denki Kagaku Kogyo Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight based on the total solid content). By applying the resin composition to form a protective layer having a thickness of about 10 μm, a charging roller having a diameter of 12 mm was obtained.

  As described above, the charging rollers obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were evaluated using the image forming apparatus shown in FIG.

(Test 1)
Using the image forming apparatus shown in FIG. 2, 300,000 copies were made in an environment of 23 ° C. and 60% RH, and the number of durable sheets until a roller crack occurred was examined. At this time, a spacer tape as a gap regulating member was attached to both ends of the charging roller, and the gap between the charging roller and the photosensitive member was arranged to be 50 μm. The voltage applied to the charging roller was DC = −800 V and AC = 2400 Vpp (frequency = 2 KHz). The evaluation environment was 23 ° C. and 60% RH. The test results are shown in Table 1. In the charging rollers of Examples 1 to 5, cracks did not occur in copying 300,000 sheets, but cracks occurred in the rollers of Comparative Examples 1 to 5. The test results are shown in Table 1 below.

(Test 2)
Using the image forming apparatus shown in FIG. 2, the charged potential of the photoreceptor and image evaluation were performed. At this time, a spacer tape as a gap regulating member was attached to both ends of the charging roller, and the gap between the charging roller and the photosensitive member was arranged to be 50 μm. The voltage applied to the charging roller was DC = −800 V, AC = 2400 Vpp (frequency = 2 KHz), and the evaluation environment was 23 ° C. and 60% RH. Next, image evaluation after continuous copying of 100,000 sheets was performed. At that time, the evaluation environment was 23 ° C. and 60% RH. The test results are shown in Table 2. In the charging rollers of Examples 1 to 5, good results were obtained in all items, but the charging rollers of Comparative Examples 1 to 5 had problems.

(Test 3)
In the same manner as in Test 2, the charging potential of the photoreceptor and image evaluation were performed using the image forming apparatus shown in FIG. At this time, the evaluation environment was 23 ° C. and 60% RH. The test results are shown in Table 3 and FIG. In the charging rollers of Examples 1 to 5, good results were obtained in all items, but in the charging rollers of Comparative Examples 1 to 5, there were problems on the image at low temperature and low humidity and at high temperature and high humidity. It was.

It is sectional drawing of the charging roller which shows one embodiment of this invention. It is explanatory drawing of the image forming apparatus using the conventional charging roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Electrical resistance adjustment layer 3 Protective layer 10 Charging member (charging roller)

Claims (7)

  In a charging member having an electric resistance adjusting layer formed on a conductive support and a protective layer coated on the surface of the electric resistance adjusting layer, the electric resistance adjusting layer comprises (A) a styrene-based thermoplastic A resin composition obtained by melt-kneading a resin, (B) a polymer ion conductive material, and (C) a heat-resistant stabilizer comprising a phenol-based antioxidant, a phosphorus-based processing heat stabilizer, and a lactone-based processing heat stabilizer. A charging member characterized by being configured.   The charging member according to claim 1, wherein the polymer ion conductive material is a polyether ester amide-containing compound.   The blending ratio of the resin composition is (A) 30 to 70% by weight and (B) 70 to 30% by weight, and the blending amount of (C) is (A) and (B). The charging member according to claim 1, wherein the charging member is 0.01 to 0.5 part by weight with respect to a total of 100 parts by weight.   The compounding ratio of each component contained in (C) is 30 to 60% by weight of a phenolic antioxidant, 40 to 70% by weight of a phosphorus processing heat stabilizer, and 1 to 30% by weight of a lactone processing heat stabilizer. The charging member according to claim 1, wherein the charging member is%.   The protective layer is composed of a resin selected from an acrylic silicon resin, a fluorine resin, a silicone resin, an acrylic resin, a polyamide resin, a polyurethane resin, a polyester resin, and a polyvinyl butyral resin. 5. The charging member according to any one of 4 above.   6. A process cartridge, wherein the charging member according to claim 1 is provided so as to be disposed close to a member to be charged.   An image forming apparatus comprising the process cartridge according to claim 6.

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