JP4925675B2 - Conductive elastic roller and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a conductive elastic roller and an image forming apparatus provided with the conductive elastic roller, and is particularly suitable as a developing roller and a charging roller, and has an elastic layer with improved contamination on adjacent members such as a photoreceptor. The present invention relates to a conductive elastic roller.

  In general, in an electrophotographic image forming apparatus such as a copying machine, a facsimile, or a laser beam printer (LBP), a developing roller, a charging roller, a toner supply roller, a transfer roller, a paper feeding roller, a cleaning roller, and a pressure for fixing. As a roller or the like, a roll-shaped conductive elastic member, i.e., a conductive elastic roller, is often used, and the conductive elastic roller is usually provided with a shaft member that is attached by being supported at both ends in the length direction, And one or more elastic layers disposed on the radially outer side of the shaft member.

  For the shaft member of the conductive elastic roller, various resins such as engineering plastics are used in addition to metals such as iron and stainless steel. On the other hand, various thermosetting resins such as a thermosetting urethane resin are used for the elastic layer of the conductive elastic roller, and a resin raw material is injected into a mold having a desired cavity shape and heated. It is manufactured by heat-curing a resin raw material (see Patent Document 1 below).

JP 2004-150610 A

  However, when producing a conductive elastic roller using a thermosetting urethane resin or the like for the elastic layer, it is necessary to heat and cure the resin raw material, which requires a large amount of heat energy, and is also suitable for curing. It took time. In addition, there is a problem that a large amount of equipment costs such as a curing furnace are required for heat curing.

  On the other hand, the present inventors examined a conductive elastic roller using an ultraviolet curable resin instead of a thermosetting resin for the elastic layer, but an ultraviolet curable resin using a general urethane acrylate oligomer. Was found to be highly contaminated to adjacent members. Here, when a roller having an elastic layer that is highly contaminating adjacent members is used as a developing roller or the like of an image forming apparatus, adjacent members such as a photoreceptor are contaminated, and image defects are likely to occur. Therefore, the elastic layer of the conductive elastic roller needs to have a sufficiently low contamination to adjacent members.

  Therefore, an object of the present invention is to solve the above-described problems of the prior art, and can be manufactured in a short time without requiring a large amount of heat energy, and does not require a large amount of equipment cost. It is an object of the present invention to provide a conductive elastic roller having improved contamination on adjacent members. Another object of the present invention is to provide an image forming apparatus that can stably form a good image using such a conductive elastic roller.

  As a result of intensive studies to achieve the above object, the present inventor has cured a raw material composition containing a urethane acrylate oligomer synthesized using a specific raw material, a photopolymerization initiator, and a conductive agent by ultraviolet irradiation to thereby form an elastic layer. By forming the conductive elastic roller, it is possible to manufacture in a short time without requiring a large amount of heat energy, and does not require a large amount of equipment cost. Has been found, and the present invention has been completed.

That is, the conductive elastic roller of the present invention comprises a shaft member and one or more elastic layers disposed on the outer side in the radial direction of the shaft member,
At least one layer of the elastic layer is made of an ultraviolet curable resin obtained by curing an elastic layer material containing a urethane acrylate oligomer (A), a photopolymerization initiator (B) and a conductive agent (C) by ultraviolet irradiation,
The urethane acrylate oligomer (A) includes a polymer chain derived from polytetramethylene glycol.

  In a preferred example of the conductive elastic roller of the present invention, the polytetramethylene glycol used for the synthesis of the urethane prepolymer has a molecular weight of 650 to 3,000.

  In another preferred embodiment of the conductive elastic roller of the present invention, the mass ratio (a1 / a2) between the polytetramethylene glycol (a1) and the other polyol (a2) used for the synthesis of the urethane prepolymer is 100/0. It is in the range of ~ 30/70.

  In another preferred embodiment of the conductive elastic roller of the present invention, the elastic layer material further contains an acrylate monomer (D).

  In another preferred embodiment of the conductive elastic roller of the present invention, the conductive agent (C) is an ionic conductive agent.

In the conductive elastic roller of the present invention, the elastic layer material used for the ultraviolet curable resin is:
The mass ratio (A / D) of the urethane acrylate oligomer (A) and the acrylate monomer (D) is in the range of 100/0 to 10/90,
For a total of 100 parts by mass of the urethane acrylate oligomer (A) and the acrylate monomer (D), the photopolymerization initiator (B) is 0.2 to 5.0 parts by mass, and the conductive agent (C) is 0.1 to 5.0 parts by mass. It is preferable to contain a part.

In another preferred embodiment of the conductive elastic roller of the present invention, the shaft member is a metal shaft or a shaft in which a highly rigid resin base material is disposed outside the metal shaft,
The outer diameter of the metal shaft is 4.0 to 8.0 mm, and the outer diameter of the resin base material is 10 to 25 mm.

  In the conductive elastic roller of the present invention, the elastic layer preferably has an Asker C hardness of 30 to 70 degrees, and preferably has a thickness of 1 to 3000 μm.

  The conductive elastic roller of the present invention is suitable as a developing roller and a charging roller.

  The image forming apparatus of the present invention is characterized by using the conductive elastic roller.

  According to the present invention, a raw material for an elastic layer containing a urethane acrylate oligomer (A) synthesized using polytetramethylene glycol, a photopolymerization initiator (B), and a conductive agent (C) is cured by irradiation with ultraviolet rays, and is elastic. By forming at least one layer, it is possible to manufacture in a short time without requiring a large amount of heat energy, and does not require a large amount of equipment cost, and the contamination property to the adjacent member of the elastic layer is improved. A conductive elastic roller can be provided. Further, it is possible to provide an image forming apparatus that includes such a conductive elastic roller and can stably form a good image.

<Conductive elastic roller>
Hereinafter, the conductive elastic roller of the present invention will be described in detail with reference to FIG. FIG. 1 is a cross-sectional view of an example of the conductive elastic roller of the present invention. The conductive elastic roller 1 in the illustrated example includes a shaft member 2 that is attached with both end portions in the length direction being pivotally supported, and an elastic layer 3 that is disposed on the outer side in the radial direction of the shaft member 2. The conductive elastic roller 1 shown in FIG. 1 has only one elastic layer 3, but the conductive elastic roller of the present invention may have two or more elastic layers. Although not shown, the conductive elastic roller of the present invention may include a coating layer on the radially outer side of the elastic layer 3.

  In FIG. 1, the shaft member 2 is composed of a metal shaft 2A and a highly rigid resin base material 2B disposed on the outer side in the radial direction of the metal shaft 2A. The shaft member of the conductive elastic roller of the present invention is As long as it has good electrical conductivity, there is no particular limitation, and it may be composed only of the metal shaft 2A, may be composed only of a highly rigid resin base material, or is made of a metal whose interior is hollowed Alternatively, it may be a cylindrical body made of a highly rigid resin. In addition, when using highly rigid resin for the shaft member 2, it is preferable to ensure sufficient electroconductivity by adding and dispersing a conductive agent in the highly rigid resin. Here, as the conductive agent dispersed in the high-rigidity resin, carbon black powder, graphite powder, carbon fiber, metal powder such as aluminum, copper and nickel, metal oxide powder such as tin oxide, titanium oxide and zinc oxide, conductive A powdery conductive agent such as conductive glass powder is preferred. These electrically conductive agents may be used individually by 1 type, and may be used in combination of 2 or more type. The blending amount of the conductive agent is not particularly limited, but is preferably in the range of 5 to 40% by mass, and more preferably in the range of 5 to 20% by mass with respect to the entire highly rigid resin.

  Examples of the material of the metal shaft 2A and the metal cylinder include iron, stainless steel, and aluminum. The material of the high-rigidity resin base material 2B includes polyacetal, polyamide 6, polyamide 6 · 6, polyamide 12, polyamide 4 · 6, polyamide 6 · 10, polyamide 6 · 12, polyamide 11, polyamide MXD6, poly Butylene terephthalate, polyphenylene oxide, polyphenylene sulfide, polyethersulfone, polycarbonate, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone, polyethylene terephthalate, polyarylate, liquid crystal polymer, polytetrafluoroethylene, polypropylene, ABS resin, Examples include polystyrene, polyethylene, melamine resin, phenol resin, and silicone resin. Among these, polyacetal, polyamide 6/6, polyamide MXD6, polyamide 6/12, polybutylene terephthalate, polyphenylene ether, polyphenylene sulfide, and polycarbonate are preferable. These highly rigid resins may be used alone or in combination of two or more.

  When the shaft member is a metal shaft or a shaft having a highly rigid resin base disposed on the outside of the metal shaft, the outer diameter of the metal shaft is preferably in the range of 4.0 to 8.0 mm. Further, when the shaft member is a shaft in which a highly rigid resin base material is disposed outside the metal shaft, the outer diameter of the resin base material is preferably in the range of 10 to 25 mm. In addition, even if the outer diameter of a shaft member is enlarged by using high rigidity resin for the said shaft member, the increase in the mass of a shaft member can be suppressed.

  The conductive elastic roller of the present invention is obtained by curing an elastic layer raw material containing at least one elastic layer containing a urethane acrylate oligomer (A), a photopolymerization initiator (B) and a conductive agent (C) by ultraviolet irradiation. Made of an ultraviolet curable resin. In addition, various additives can be mix | blended with this raw material for elastic layers, unless the objective of this invention is impaired.

The urethane acrylate oligomer (A) used for the elastic layer material includes a polymer chain derived from polytetramethylene glycol, such as polytetramethylene glycol (PTMG) alone or a mixture of polytetramethylene glycol (PTMG) and other polyols. And a urethane prepolymer synthesized from a polyisocyanate, can be synthesized by adding an acrylate having a hydroxyl group, has one or more acryloyloxy groups (CH ₂ ═CHCOO—), and has a urethane bond (—NHCOO— ). The polytetramethylene glycol used for the synthesis of the urethane prepolymer is not particularly limited, but can be produced by, for example, ring-opening polymerization of THF. When an elastic layer is formed by irradiating ultraviolet rays using a general urethane acrylate oligomer, the contamination of adjacent members of the roller is high. Surprisingly, a urethane acrylate oligomer (A) synthesized using polytetramethylene glycol is surprisingly used. By using it and forming an elastic layer by irradiating with ultraviolet rays, contamination of adjacent members of the roller can be reduced. This is because the curability of the elastic layer raw material containing the urethane acrylate oligomer (A) synthesized using polytetramethylene glycol by UV is more than the curability of the elastic layer raw material containing the general urethane acrylate oligomer by UV. This is probably due to the high price.

  The polytetramethylene glycol used for the synthesis of the urethane prepolymer preferably has a molecular weight in the range of 650 to 3,000. The molecular weight is a number average molecular weight. If the molecular weight of polytetramethylene glycol is less than 650, the hardness of the ultraviolet curable resin is too high and not suitable for a conductive elastic roller. On the other hand, if it exceeds 3,000, the liquid viscosity increases and it is not suitable for production.

  In the synthesis of the urethane prepolymer, another polyol that can be used together with the polytetramethylene glycol is a compound having a plurality of hydroxyl groups (OH groups). Examples thereof include polyester polyol, polybutadiene polyol, alkylene oxide-modified polybutadiene polyol, and polyisoprene polyol. The polyether polyol is obtained, for example, by adding an alkylene oxide such as ethylene oxide or propylene oxide to a polyhydric alcohol such as ethylene glycol, propylene glycol, or glycerin. The polyester polyol is, for example, ethylene glycol. , Diethylene glycol, 1,4-butanediol, 1,6-hexanediol, propylene glycol, trimethylolethane, trimethylolpropane and other polyhydric alcohols and adipic acid, glutaric acid, succinic acid, sebacic acid, pimelic acid, suberin It is obtained from a polyvalent carboxylic acid such as an acid. These polyols may be used alone or in a blend of two or more.

  In the synthesis of the urethane prepolymer, when another polyol (a2) is used together with the polytetramethylene glycol (a1), the mass ratio (a1 / a2) between the polytetramethylene glycol (a1) and the other polyol (a2) ) Is preferably in the range of 100/0 to 30/70. By setting the proportion of polytetramethylene glycol (a1) in the total amount (a1 + a2) of polytetramethylene glycol (a1) and other polyol (a2) to 30% by mass or more (that is, other polyol (a2) By setting the ratio to 70% by mass or less), the contamination of adjacent members such as the photosensitive member of the conductive elastic roller can be sufficiently reduced.

  The polyisocyanate used for the synthesis of the urethane prepolymer is a compound having a plurality of isocyanate groups (NCO groups). Specifically, as the polyisocyanate, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude Examples include diphenylmethane diisocyanate (crude MDI), isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, hexamethylene diisocyanate (HDI), these isocyanurate modified products, carbodiimide modified products, glycol modified products, and the like. . These polyisocyanates may be used alone or in a blend of two or more.

  In the synthesis of the urethane prepolymer, it is preferable to use a catalyst for urethanization reaction. Examples of the catalyst for urethanization reaction include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin thiocarboxylate, tin octenoate, monobutyltin oxide, and the like; stannous chloride, etc. Inorganic lead compounds; organic lead compounds such as lead octenoate; monoamines such as triethylamine and dimethylcyclohexylamine; diamines such as tetramethylethylenediamine, tetramethylpropanediamine, and tetramethylhexanediamine; pentamethyldiethylenetriamine, pentamethyldipropylene Triamines such as triamine and tetramethylguanidine; triethylenediamine, dimethylpiperazine, methylethylpiperazine, methylmorpholine, dimethyl Cyclic amines such as ruaminoethylmorpholine, dimethylimidazole, pyridine; alcohol amines such as dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methylhydroxyethylpiperazine, hydroxyethylmorpholine; bis (dimethylaminoethyl) Ethers, ether amines such as ethylene glycol bis (dimethyl) aminopropyl ether; organic sulfonic acids such as p-toluenesulfonic acid, methanesulfonic acid and fluorosulfuric acid; inorganic acids such as sulfuric acid, phosphoric acid and perchloric acid; sodium alcoholate Bases such as lithium hydroxide, aluminum alcoholate and sodium hydroxide; titanium compounds such as tetrabutyl titanate, tetraethyl titanate and tetraisopropyl titanate; Smus compounds; quaternary ammonium salts and the like. Of these catalysts, organotin compounds are preferred. These catalysts may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the catalyst used is preferably in the range of 0.001 to 2.0 parts by mass with respect to 100 parts by mass of the polyol.

The acrylate having a hydroxyl group to be added to the urethane prepolymer is a compound having one or more hydroxyl groups and one or more acryloyloxy groups (CH ₂ ═CHCOO—). The acrylate having a hydroxyl group can be added to the isocyanate group of the urethane prepolymer. Examples of the acrylate having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and pentaerythritol triacrylate. These acrylates having a hydroxyl group may be used alone or in combination of two or more.

  The photopolymerization initiator (B) used for the elastic layer raw material has an action of initiating polymerization of the above-described urethane acrylate oligomer (A) and further an acrylate monomer (D) described later by being irradiated with ultraviolet rays. . Examples of the photopolymerization initiator (B) include 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, 2,2-dimethoxy-2-phenylacetophenone, acetophenone diethyl ketal, alkoxyacetophenone, benzyldimethyl ketal, benzophenone and 3,3-dimethyl-4-methoxybenzophenone, benzophenone derivatives such as 4,4-dimethoxybenzophenone, 4,4-diaminobenzophenone, alkyl benzoylbenzoate, bis (4-dialkylaminophenyl) ketone, benzyl, benzylmethyl ketal, etc. Benzyl derivatives of benzoin, benzoin derivatives such as benzoin and benzoin isobutyl ether, benzoin isopropyl ether, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, Thioxanthone and thioxanthone derivatives, fluorene, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6- Trimethylbenzoyl) -phenylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1,2-benzyl-2-dimethylamino-1- (morpholinophenyl) -butanone-1, etc. Is mentioned. These photoinitiators may be used individually by 1 type, and may use 2 or more types together.

  The conductive agent (C) used as the elastic layer material has a function of imparting conductivity to the elastic layer. As this electrically conductive agent (C), what can permeate | transmit an ultraviolet-ray is preferable, It is preferable to use an ionic conductive agent and a transparent electronic conductive agent, and it is especially preferable to use an ionic conductive agent. Since the ionic conductive agent dissolves in the urethane acrylate oligomer (A) and has transparency, when the ionic conductive agent is used as the conductive agent (C), the elastic layer material is applied thickly on the shaft member. However, the ultraviolet rays sufficiently reach the inside of the coating film, and the elastic layer material can be sufficiently cured. Here, as the ionic conductive agent, tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, modified fatty acid dimethylethylammonium and the like perchlorate, chlorate, hydrochloride, bromate Ammonium salts such as salts, iodates, borofluorides, sulfates, ethyl sulfates, carboxylates, sulfonates; alkaline metals such as lithium, sodium, potassium, calcium, magnesium, alkaline earth metals Examples include perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, trifluoromethyl sulfate, and sulfonate. In addition, transparent electronic conductive agents include fine particles of metal oxides such as ITO, tin oxide, titanium oxide, and zinc oxide; fine particles of metals such as nickel, copper, silver, and germanium: conductive titanium oxide whiskers, conductive titanium Examples include conductive whiskers such as barium acid whiskers. These electrically conductive agents may be used individually by 1 type, and may use 2 or more types together.

The elastic layer material preferably further contains an acrylate monomer (D). The acrylate monomer (D) is a monomer having one or more acryloyloxy groups (CH ₂ ═CHCOO—), which acts as a reactive diluent, that is, is cured with ultraviolet rays and has a viscosity of the elastic layer material. It can be reduced. The acrylate monomer (D) preferably has a functional group number of 1.0 to 10 and more preferably 1.0 to 3.5. The acrylate monomer (D) preferably has a molecular weight of 100 to 2000, and more preferably 100 to 1000.

  Examples of the acrylate monomer (D) include isomyristyl acrylate, methoxytriethylene glycol acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, isoamyl acrylate, glycidyl acrylate, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydipropylene glycol acrylate, Examples include phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and pentaerythritol triacrylate. These acrylate monomers may be used alone or in combination of two or more.

  In the elastic layer raw material, the mass ratio (A / D) of the urethane acrylate oligomer (A) and the acrylate monomer (D) is preferably in the range of 100/0 to 10/90. By making the ratio of the urethane acrylate oligomer (A) in the total amount of the urethane acrylate oligomer (A) and the acrylate monomer (D) 10% by mass or more (that is, the ratio of the acrylate monomer (D) is 90% by mass or less. Thus, it is possible to obtain an elastic layer with low hardness and low compression residual strain suitable for the conductive elastic roller.

  Moreover, the compounding quantity of the photoinitiator (B) in the said raw material for elastic layers is 0.2-5.0 mass parts with respect to a total of 100 mass parts of the said urethane acrylate oligomer (A) and the said acrylate monomer (D). The range of is preferable. When the blending amount of the photopolymerization initiator (B) is 0.2 parts by mass or less, the effect of initiating UV curing of the elastic layer raw material is small, whereas when it exceeds 5.0 parts by mass, the effect of initiating UV curing is saturated. Further, physical properties such as compression residual strain are lowered, and the cost of the elastic layer raw material is increased.

  Furthermore, the compounding quantity of the electrically conductive agent (C) in the said raw material for elastic layers is the range of 0.1-5.0 mass parts with respect to a total of 100 mass parts of the said urethane acrylate oligomer (A) and the said acrylate monomer (D). Is preferred. If the blending amount of the conductive agent (C) is less than 0.1 parts by mass, the conductivity of the elastic layer may be low and desired conductivity may not be imparted to the conductive elastic roller. On the other hand, if it exceeds 5.0 parts by mass, the elastic layer In some cases, the electrical conductivity of the film does not increase, and physical properties such as compressive residual strain decrease and a good image cannot be obtained.

  Moreover, you may add 0.001-0.2 mass part of polymerization inhibitors with respect to the said raw material for elastic layers further with respect to a total of 100 mass parts of the said urethane acrylate oligomer (A) and the said acrylate monomer (D). By adding a polymerization inhibitor, thermal polymerization before ultraviolet irradiation can be prevented. Polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, p-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-p-cresol, butylhydroxyanisole, 3 -Hydroxythiophenol, α-nitroso-β-naphthol, p-benzoquinone, 2,5-dihydroxy-p-quinone and the like.

  The elastic layer preferably has an Asker C hardness of 30 to 70 degrees. Here, the Asker C hardness is a value when a flat portion of a cylindrical sample having a height of 12.7 mm and a diameter of 29 mm is measured. If the Asker C hardness is 30 degrees or more, sufficient hardness can be secured as a conductive elastic roller such as a developing roller, while if it is 70 degrees or less, followability with other rollers and blades is good. Thus, aggregation and fusion of the low melting point toner can be sufficiently prevented.

  The elastic layer preferably has a thickness of 1 to 3000 μm. If the thickness of the elastic layer is 1 μm or more, the conductive elastic roller has sufficient elasticity and the damage to the toner is sufficiently small. Is sufficiently reached, the raw material for the elastic layer can be reliably UV-cured, and the amount of high-priced UV-curing resin raw material used can be reduced.

The elastic layer is not particularly limited, but preferably has a compression residual strain (compression set) of 5% or less. Here, the compressive residual strain can be measured in accordance with JIS K 6262 (1997). Specifically, a cylindrical sample having a height of 12.7 mm and a diameter of 29 mm is subjected to a prescribed heat treatment condition (22 at 70 ° C.). Time), the sample can be determined by compressing it in the height direction by 25%. The elastic layer preferably has a volume resistivity of 10 ⁴ to 10 ¹⁰ Ωcm. Furthermore, the conductive elastic roller of the present invention preferably has a roller resistance of 10 ⁴ to 10 ¹⁰ Ω at an applied voltage of 100V. Here, the resistance value is obtained from a current value at that time by applying a voltage of 100 V between the shaft and the counter electrode by pressing the outer peripheral surface of the conductive elastic roller to a flat plate or a cylindrical counter electrode with a predetermined pressure. be able to.

  The conductive elastic roller of the present invention can be produced by applying the elastic layer raw material to the outer surface of the shaft member and then irradiating it with ultraviolet rays. Therefore, the conductive elastic roller of the present invention does not require a large amount of heat energy for the production of the elastic layer, and can produce the elastic layer in a short time. Moreover, since a curing furnace or the like is not required for forming the elastic layer, a large amount of equipment costs are not required. Examples of the method for applying the elastic layer raw material to the outer surface of the shaft member include a spray method, a roll coater method, a dipping method, and a die coating method. Examples of the light source used for ultraviolet irradiation include a mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, and a xenon lamp. The conditions for ultraviolet irradiation are appropriately selected according to the components, composition, coating amount and the like contained in the elastic layer raw material, and the irradiation intensity and the integrated light amount may be adjusted as appropriate.

  The conductive elastic roller of the present invention described above can be used as a developing roller, a charging roller, a toner supply roller, a transfer roller, a paper feed roller, a cleaning roller, a fixing pressure roller, and the like of an image forming apparatus. Particularly suitable as a developing roller and a charging roller.

<Image forming apparatus>
The image forming apparatus of the present invention includes the above-described conductive elastic roller, and preferably includes at least one of a developing roller and a charging roller. The image forming apparatus of the present invention is not particularly limited except that the conductive elastic roller is used, and can be manufactured by a known method.

  The image forming apparatus of the present invention will be described in detail below with reference to FIG. FIG. 2 is a partial cross-sectional view of an example of the image forming apparatus of the present invention. The image forming apparatus of the illustrated example supplies a photosensitive member 4 holding an electrostatic latent image, a charging roller 5 that is positioned in the vicinity of the photosensitive member 4 (upward in the drawing) and charges the photosensitive member 4, and a toner 6. A toner supply roller 7, a developing roller 8 disposed between the toner supply roller 7 and the photosensitive member 4, a stratification blade 9 provided in the vicinity of the developing roller 8 (upward in the drawing), and a photosensitive member. 4 is provided with a transfer roller 10 located near (lower in the drawing) 4 and a cleaning roller 11 disposed adjacent to the photoreceptor 4. The image forming apparatus of the present invention can further include a known component (not shown) that is usually used in the image layer forming apparatus.

  In the illustrated image forming apparatus, the charging roller 5 is brought into contact with the photosensitive member 4 and a voltage is applied between the photosensitive member 4 and the charging roller 5 to charge the photosensitive member 4 to a constant potential. Then, an electrostatic latent image is formed on the photoreceptor 4 by an exposure machine (not shown). Next, the photosensitive member 4, the toner supply roller 7, and the developing roller 8 rotate in the direction of the arrow in the figure, so that the toner 6 on the toner supply roller 7 is sent to the photosensitive member 4 through the developing roller 8. It is done. The toner 6 on the developing roller 8 is adjusted to a uniform thin layer by the stratifying blade 9 and rotates while the developing roller 8 and the photosensitive member 4 are in contact with each other, whereby the toner 6 is transferred from the developing roller 8 to the photosensitive member 4. It adheres to the electrostatic latent image and the latent image becomes visible. The toner 6 attached to the latent image is transferred to a recording medium such as paper by the transfer roller 10, and the toner 6 remaining on the photoreceptor 4 after the transfer is removed by the cleaning roller 11. Here, in the image forming apparatus of the present invention, at least one of the charging roller 5, the toner supply roller 7, the developing roller 8, the transfer roller 10 and the cleaning roller 11, preferably at least the charging roller 5 and the developing roller 8. On the other hand, it is possible to stably form an excellent image by using the above-described conductive elastic roller of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Example 1
Bifunctional polytetramethylene glycol with a molecular weight of 2900 [PTG-2900SN, Hodogaya Chemical Co., Ltd.] 50 parts by mass, isomyristyl acrylate [Light acrylate IM-A, Kyoeisha Chemical Co., Ltd.] 50 parts by mass, isophorone diisocyanate 5.5 parts by mass Part (isocyanate index 150) and 0.01 part by weight of dibutyltin dilaurate were reacted at 70 ° C. for 2 hours while heating and stirring to synthesize a urethane prepolymer having isocyanate groups at both ends of the molecular chain. The obtained urethane prepolymer had an NCO group content of 0.65%. Further, 1.8 parts by mass of 2-hydroxyethyl acrylate (HEA) was stirred and mixed with 100 parts by mass of this urethane prepolymer, and reacted at 70 ° C. for 2 hours to obtain a urethane acrylate oligomer (A-1) having a molecular weight of 7000 for acrylate monomer dilution. ) Was synthesized (acrylate monomer content 46.6%).

  70.0 parts by mass of the urethane acrylate oligomer (A-1), 30.0 parts by mass of an acrylate monomer “light acrylate IM-A (isomyristyl acrylate)” manufactured by Kyoeisha Chemical Co., Ltd., photopolymerization manufactured by Ciba Specialty Chemicals Co., Ltd. Initiator "Irgacure 184D" 0.5 parts by mass and Akishima Chemical Industry Co., Ltd. ionic conductive agent "MP-100" 2.0 parts by mass with a stirrer at a liquid temperature of 70 ° C and 60 rpm for 1 hour After mixing, the mixed solution was filtered to obtain a UV curable resin raw material. The mass ratio of urethane acrylate oligomer to acrylate monomer in this formulation is 37.4 / 62.6.

The above UV curable resin raw material is poured into a mold having a cavity with a depth of 12.7 mm and an inner diameter of 29 mm, covered with a quartz glass plate, and then irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 10 seconds to measure cylindrical physical properties. A UV curable resin sample was obtained. This sample had an Asker C hardness (manufactured by Kobunshi Keiki Co., Ltd.) of 46 degrees in the flat portion.

Next, the above UV curable resin raw material is applied to a conductive roller base material made of polybutylene terephthalate (PBT) resin having an outer diameter of 17.0 mm into which a metal shaft having an outer diameter of 6.0 mm is inserted, with a thickness of 1500 μm using a die coater. The UV curable resin raw material was cured by spot UV irradiation. The UV-cured resin elastic layer-formed roller thus formed was further irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 5 seconds while rotating in a nitrogen atmosphere.

  On the surface of the roller with an elastic layer made of UV curable resin thus obtained, a UV curable resin material containing fine particles having hardness higher than that of the elastic layer is applied with a roll coater, and irradiated with UV to form a UV coating on the surface. A low hardness UV resin roller having an outer diameter of 20.0 mm was obtained. When this roller was incorporated into an electrophotographic apparatus as a developing roller and solid white, black solid, and gray scale images were printed, a good image could be obtained.

  Next, for the photoreceptor contamination test, the cartridge incorporating the roller was left in a hot air circulation oven shielded from light at 50 ° C. for 5 days, then taken out and left for 1 hour in an environment of 20 ° C. and 50% RH. Subsequently, when 50 gray images were printed, a good image was obtained, and no image defect due to photoconductor contamination was observed.

(Example 2)
Bifunctional polytetramethylene glycol [PTG-2900SN, Hodogaya Chemical Co., Ltd.] 50 parts by mass, isomyristyl acrylate [Light acrylate IM-A, Kyoeisha Chemical Co., Ltd.] 50 parts by mass, isophorone diisocyanate 4.9 parts by mass Part (isocyanate index 133) and 0.01 part by weight of dibutyltin dilaurate were reacted at 70 ° C. for 2 hours with heating and stirring to synthesize a urethane prepolymer having isocyanate groups at both ends of the molecular chain. The NCO group content of the obtained urethane prepolymer was 0.43%. Further, 1.2 parts by mass of 2-hydroxyethyl acrylate (HEA) was stirred and mixed with 100 parts by mass of this urethane prepolymer and reacted at 70 ° C. for 2 hours to obtain a urethane acrylate oligomer (A-2 having a molecular weight of 10,000 acrylate monomer dilution). ) Was synthesized (acrylate monomer content 47.1%).

  70.0 parts by mass of the urethane acrylate oligomer (A-2), 30.0 parts by mass of an acrylate monomer “Light Acrylate IM-A” manufactured by Kyoeisha Chemical Co., Ltd., a photopolymerization initiator “Irgacure manufactured by Ciba Specialty Chemicals Co., Ltd.” 184D "0.5 parts by mass and 2.0 parts by mass of ionic conductive agent" MP-100 "manufactured by Akishima Chemical Industry Co., Ltd. were stirred and mixed with a stirrer at a liquid temperature of 70 ° C and 60 rpm for 1 hour. Was filtered to obtain a UV curable resin raw material. The mass ratio of urethane acrylate oligomer and acrylate monomer in this formulation is 37.0 / 63.0.

The above UV curable resin raw material is poured into a mold having a cavity with a depth of 12.7 mm and an inner diameter of 29 mm, covered with a quartz glass plate, and then irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 10 seconds to measure cylindrical physical properties. A UV curable resin sample was obtained. This sample had an Asker C hardness (manufactured by Kobunshi Keiki Co., Ltd.) of 42 degrees in the plane portion.

Next, the above UV curable resin raw material is applied to a PBT resin conductive roller base material having an outer diameter of 17.0 mm inserted with a metal shaft having an outer diameter of 6.0 mm with a die coater at a thickness of 1500 μm, and is applied by spot UV irradiation while being applied. The UV curable resin raw material was cured. The UV-cured resin elastic layer-formed roller thus formed was further irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 5 seconds while rotating in a nitrogen atmosphere.

  On the surface of the roller with an elastic layer made of UV curable resin thus obtained, a UV curable resin material containing fine particles having hardness higher than that of the elastic layer is applied with a roll coater, and irradiated with UV to form a UV coating on the surface. A low hardness UV resin roller having an outer diameter of 20.0 mm was obtained. When this roller was incorporated into an electrophotographic apparatus as a developing roller and solid white, black solid, and gray scale images were printed, a good image could be obtained.

  Next, for the photoreceptor contamination test, the cartridge incorporating the roller was left in a hot air circulation oven shielded from light at 50 ° C. for 5 days, then taken out and left for 1 hour in an environment of 20 ° C. and 50% RH. Subsequently, when 50 gray images were printed, a good image was obtained, and no image defect due to photoconductor contamination was observed.

(Example 3)
Bifunctional and molecular weight 1000 polytetramethylene glycol [PTG-1000SN, Hodogaya Chemical Co., Ltd.] 50 parts by mass, isomyristyl acrylate [Light acrylate IM-A, Kyoeisha Chemical Co., Ltd.] 50 parts by mass, isophorone diisocyanate 12.9 parts by mass Part (isocyanate index 117) and 0.01 part by weight of dibutyltin dilaurate were reacted at 70 ° C. for 2 hours with heating and stirring to synthesize a urethane prepolymer having isocyanate groups at both ends of the molecular chain. The NCO group content of the obtained urethane prepolymer was 0.63%. Furthermore, 1.7 parts by mass of 2-hydroxyethyl acrylate (HEA) was stirred and mixed with 100 parts by mass of this urethane prepolymer and reacted at 70 ° C. for 2 hours to obtain a urethane acrylate oligomer (A-3 having a molecular weight of 8000 as the acrylate monomer dilution). ) (Acrylate monomer content 43.5%).

  50.0 parts by mass of the above urethane acrylate oligomer (A-3), 50.0 parts by mass of acrylate monomer “light acrylate MTG-A (methoxytriethylene glycol acrylate)” manufactured by Kyoeisha Chemical Co., Ltd., manufactured by Ciba Specialty Chemicals Co., Ltd. A photopolymerization initiator "Irgacure 184D" 0.5 parts by mass and an ionic conductive agent "MP-100" 2.0 parts by mass produced by Akishima Chemical Industry Co., Ltd. were stirred at a liquid temperature of 70 ° C and 60 rpm. The mixture was stirred for an hour and the mixture was filtered to obtain a UV curable resin raw material. The mass ratio of urethane acrylate oligomer to acrylate monomer in this formulation is 28.2 / 71.8.

The above UV curable resin raw material is poured into a mold having a cavity with a depth of 12.7 mm and an inner diameter of 29 mm, covered with a quartz glass plate, and then irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 10 seconds to measure cylindrical physical properties. A UV curable resin sample was obtained. This sample had an Asker C hardness (manufactured by Kobunshi Keiki Co., Ltd.) of 53 degrees in the plane portion.

Next, the above UV curable resin raw material is applied to a PBT resin conductive roller base material having an outer diameter of 17.0 mm inserted with a metal shaft having an outer diameter of 6.0 mm with a die coater at a thickness of 1500 μm, and is applied by spot UV irradiation while being applied. The UV curable resin raw material was cured. The UV-cured resin elastic layer-formed roller thus formed was further irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 5 seconds while rotating in a nitrogen atmosphere.

  On the surface of the roller with an elastic layer made of UV curable resin thus obtained, a UV curable resin material containing fine particles having hardness higher than that of the elastic layer is applied with a roll coater, and irradiated with UV to form a UV coating on the surface. A low hardness UV resin roller having an outer diameter of 20.0 mm was obtained. When this roller was incorporated into an electrophotographic apparatus as a developing roller and solid white, black solid, and gray scale images were printed, a good image could be obtained.

  Next, for the photoreceptor contamination test, the cartridge incorporating the roller was left in a hot air circulation oven shielded from light at 50 ° C. for 5 days, then taken out and left for 1 hour in an environment of 20 ° C. and 50% RH. Subsequently, when 50 gray images were printed, a good image was obtained, and no image defect due to photoconductor contamination was observed.

Example 4
25 parts by mass of polytetramethylene glycol [PTG-2900SN, Hodogaya Chemical Co., Ltd.] with a molecular weight of 2900 and 25 parts by mass of polyoxypropylene glycol [Exenol 3020] with a molecular weight of 3200, isomyristyl acrylate [light acrylate IM-A, Kyoeisha Chemical Co., Ltd.] 50 parts by mass, isophorone diisocyanate 5.3 parts by mass (isocyanate index 150), and dibutyltin dilaurate 0.01 parts by mass while stirring and mixing at 70 ° C. for 2 hours, molecular chain A urethane prepolymer having isocyanate groups at both ends was synthesized. The NCO group content of the obtained urethane prepolymer was 0.63%. Furthermore, 1.8 parts by mass of 2-hydroxyethyl acrylate (HEA) was stirred and mixed with 100 parts by mass of this urethane prepolymer, and reacted at 70 ° C. for 2 hours to obtain a urethane acrylate oligomer (A-4 having a molecular weight of 7000 acrylate monomer dilution). ) Was synthesized (acrylate monomer content 46.6%).

  70.0 parts by mass of the above urethane acrylate oligomer (A-4), 30.0 parts by mass of acrylate monomer “Light Acrylate IM-A” manufactured by Kyoeisha Chemical Co., Ltd., “Irgacure” photopolymerization initiator manufactured by Ciba Specialty Chemicals Co., Ltd. 184D "0.5 parts by mass and 2.0 parts by mass of ionic conductive agent" MP-100 "manufactured by Akishima Chemical Industry Co., Ltd. were stirred and mixed with a stirrer at a liquid temperature of 70 ° C and 60 rpm for 1 hour. Was filtered to obtain a UV curable resin raw material. The mass ratio of urethane acrylate oligomer to acrylate monomer in this formulation is 37.4 / 62.6.

The above UV curable resin raw material is poured into a mold having a cavity with a depth of 12.7 mm and an inner diameter of 29 mm, covered with a quartz glass plate, and then irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 10 seconds to measure cylindrical physical properties. A UV curable resin sample was obtained. This sample had an Asker C hardness (manufactured by Kobunshi Keiki Co., Ltd.) of 43 degrees in the plane portion.

Next, the above UV curable resin raw material is applied to a PBT resin conductive roller base material having an outer diameter of 17.0 mm inserted with a metal shaft having an outer diameter of 6.0 mm with a die coater at a thickness of 1500 μm, and is applied by spot UV irradiation while being applied. The UV curable resin raw material was cured. The UV-cured resin elastic layer-formed roller thus formed was further irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 5 seconds while rotating in a nitrogen atmosphere.

  On the surface of the roller with an elastic layer made of UV curable resin thus obtained, a UV curable resin material containing fine particles having hardness higher than that of the elastic layer is applied with a roll coater, and irradiated with UV to form a UV coating on the surface. A low hardness UV resin roller having an outer diameter of 20.0 mm was obtained. When this roller was incorporated into an electrophotographic apparatus as a developing roller and solid white, black solid, and gray scale images were printed, a good image could be obtained.

  Next, for the photoreceptor contamination test, the cartridge incorporating the roller was left in a hot air circulation oven shielded from light at 50 ° C. for 5 days, then taken out and left for 1 hour in an environment of 20 ° C. and 50% RH. Subsequently, when 50 gray images were printed, a good image was obtained, and no image defect due to photoconductor contamination was observed.

(Comparative Example 1)
20% urethane acrylate oligomer “UA-340P (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester APG-700 (polypropylene glycol # 700 diacrylate, molecular weight = 808)) using a polyol having a polyoxypropylene chain as a raw material. Contained] "80.0 parts by mass, acrylate monomer" Light acrylate IM-A [manufactured by Kyoeisha Chemical Co., Ltd.] "20.0 parts by mass, photopolymerization initiator" Irgacure 184D [manufactured by Ciba Specialty Chemicals Co., Ltd.] "0.5 mass And 2.0 parts by mass of the ionic conductive agent “MP-100 [Akishima Chemical Industry Co., Ltd.]” were stirred and mixed for 1 hour at a liquid temperature of 70 ° C. and 60 rpm, and the mixture was filtered. Thus, a UV curable resin material was obtained. The mass ratio of urethane acrylate oligomer to acrylate monomer in this formulation is 64.0 / 36.0.

The above UV curable resin raw material is poured into a mold having a cavity with a depth of 12.7 mm and an inner diameter of 29 mm, covered with a quartz glass plate, and then irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 10 seconds to measure cylindrical physical properties. A UV curable resin sample was obtained. This sample had an Asker C hardness (manufactured by Kobunshi Keiki Co., Ltd.) of 52 degrees in the flat portion.

Next, the above UV curable resin raw material is applied to a PBT resin conductive roller base material having an outer diameter of 17.0 mm inserted with a metal shaft having an outer diameter of 6.0 mm with a die coater at a thickness of 1500 μm, and is applied by spot UV irradiation while being applied. The UV curable resin raw material was cured. The UV-cured resin elastic layer-formed roller thus formed was further irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 5 seconds while rotating in a nitrogen atmosphere.

  On the surface of the roller with an elastic layer made of UV curable resin thus obtained, a UV curable resin material containing fine particles having hardness higher than that of the elastic layer is applied with a roll coater, and irradiated with UV to form a UV coating on the surface. A low hardness UV resin roller having an outer diameter of 20.0 mm was obtained. When this roller was incorporated into an electrophotographic apparatus as a developing roller and solid white, black solid, and gray scale images were printed, a good image could be obtained.

  Next, for the photoreceptor contamination test, the cartridge incorporating this roller was left in a hot air circulation oven shielded from light at 50 ° C. for 5 days, then taken out and left for 1 hour in an environment of 20 ° C. and 50% RH. Later, when 50 gray images were printed, equally spaced white lines appeared in the image, and it was confirmed that the image was defective due to photoconductor contamination from the distance of the interval.

(Comparative Example 2)
Urethane acrylate oligomer “CN-962 [manufactured by SARTOMER COMPANY, oligomer component 100%, monomer component 0%]” 50.0 parts by mass, acrylate monomer “light acrylate MTG-A [Kyoeisha Chemical Co., Ltd.] Co., Ltd., Methoxytriethylene glycol acrylate] ”50.0 parts by mass, photopolymerization initiator“ Irgacure 184D [Ciba Specialty Chemicals Co., Ltd.] ”0.5 parts by mass, and ionic conductive agent“ MP-100 [Akishima] Chemical Industry Co., Ltd.] ”2.0 parts by mass was stirred and mixed with a stirrer at a liquid temperature of 70 ° C. and 60 rpm for 1 hour, and the mixture was filtered to obtain a UV curable resin raw material. The mass ratio of urethane acrylate oligomer and acrylate monomer in this formulation is 50.0 / 50.0.

The above UV curable resin raw material is poured into a mold having a cavity with a depth of 12.7 mm and an inner diameter of 29 mm, covered with a quartz glass plate, and then irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 10 seconds to measure cylindrical physical properties. A UV curable resin sample was obtained. This sample had an Asker C hardness (manufactured by Kobunshi Keiki Co., Ltd.) of 53 degrees in the plane portion.

Next, the above UV curable resin raw material is applied to a PBT resin conductive roller base material having an outer diameter of 17.0 mm inserted with a metal shaft having an outer diameter of 6.0 mm with a die coater at a thickness of 1500 μm, and is applied by spot UV irradiation while being applied. The UV curable resin raw material was cured. The UV-cured resin elastic layer-formed roller thus formed was further irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 5 seconds while rotating in a nitrogen atmosphere.

  On the surface of the roller with an elastic layer made of UV curable resin thus obtained, a UV curable resin material containing fine particles having hardness higher than that of the elastic layer is applied with a roll coater, and irradiated with UV to form a UV coating on the surface. A low hardness UV resin roller having an outer diameter of 20.0 mm was obtained. When this roller was incorporated into an electrophotographic apparatus as a developing roller and solid white, black solid, and gray scale images were printed, a good image could be obtained.

  Next, for the photoreceptor contamination test, the cartridge incorporating this roller was left in a hot air circulation oven shielded from light at 50 ° C. for 5 days, then taken out and left for 1 hour in an environment of 20 ° C. and 50% RH. Later, when 50 gray images were printed, equally spaced white lines appeared in the image, and it was confirmed that the image was defective due to photoconductor contamination from the distance of the interval.

  From Examples 1 to 4, the elastic layer raw material containing the urethane acrylate oligomer (A) synthesized using polytetramethylene glycol, the photopolymerization initiator (B), and the conductive agent (C) was cured by ultraviolet irradiation. It can be seen that the conductive elastic roller having an elastic layer made of an ultraviolet curable resin does not contaminate the photoreceptor.

  On the other hand, when an elastic layer is formed using a urethane acrylate oligomer synthesized using polyols having polyoxypropylene chains or polyols having polyester chains from Comparative Examples 1 and 2, the conductive elastic roller contaminates the photoreceptor. It can be seen that an image defect occurs.

It is sectional drawing of an example of the electroconductive elastic roller of this invention. 1 is a partial cross-sectional view of an example of an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive elastic roller 2 Shaft member 2A Metal shaft 2B High-rigidity resin base material 3 Elastic layer 4 Photoconductor 5 Charging roller 6 Toner 7 Toner supply roller 8 Developing roller 9 Stratified blade 10 Transfer roller 11 Cleaning roller

Claims (11)

In a conductive elastic roller comprising a shaft member and one or more elastic layers disposed radially outside the shaft member,
At least one layer of the elastic layer is made of an ultraviolet curable resin obtained by curing a raw material for an elastic layer containing a urethane acrylate oligomer (A), a photopolymerization initiator (B), and a conductive agent (C) by ultraviolet irradiation,
The conductive elastic roller, wherein the urethane acrylate oligomer (A) includes a polymer chain derived from polytetramethylene glycol.   The conductive elastic roller according to claim 1, wherein the molecular weight of polytetramethylene glycol used for the synthesis of the urethane prepolymer is 650 to 3,000.   The mass ratio (a1 / a2) between the polytetramethylene glycol (a1) and the other polyol (a2) used for the synthesis of the urethane prepolymer is in the range of 100/0 to 30/70. 2. The conductive elastic roller according to 1.   The conductive elastic roller according to claim 1, wherein the elastic layer material further contains an acrylate monomer (D).   The conductive elastic roller according to claim 1, wherein the conductive agent (C) is an ionic conductive agent. The elastic layer material used for the ultraviolet curable resin is:
The mass ratio (A / D) of the urethane acrylate oligomer (A) and the acrylate monomer (D) is in the range of 100/0 to 10/90,
For a total of 100 parts by mass of the urethane acrylate oligomer (A) and the acrylate monomer (D), the photopolymerization initiator (B) is 0.2 to 5.0 parts by mass, and the conductive agent (C) is 0.1 to 5.0 parts by mass. 5. The conductive elastic roller according to claim 1, comprising a part.   The conductive elastic roller according to claim 1, wherein the elastic layer has an Asker C hardness of 30 to 70 degrees. The shaft member is a metal shaft or a shaft in which a highly rigid resin base material is disposed outside the metal shaft;
2. The conductive elastic roller according to claim 1, wherein an outer diameter of the metal shaft is 4.0 to 8.0 mm and an outer diameter of the resin base material is 10 to 25 mm.   The conductive elastic roller according to claim 1, wherein the elastic layer has a thickness of 1 to 3000 μm.   The conductive elastic roller according to claim 1, wherein the conductive elastic roller is a developing roller or a charging roller.   An image forming apparatus using the conductive elastic roller according to claim 1.

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