JP4679556B2 - Conductive roller and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a conductive roller and an image forming apparatus using the conductive roller, and more particularly to a conductive roller having an elastic layer that is suitable as a developing roller and has improved contamination on adjacent members such as a photoreceptor. is there.

  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 member, i.e., a conductive roller, is often used. The conductive roller is usually attached to a shaft member that is supported by both ends in the length direction, and the shaft member. And one or more elastic layers disposed radially outward. In addition, the surface of the said elastic layer may be provided with coating films, such as an intermediate | middle layer and a surface layer.

  In a state where the image forming apparatus is left without being operated, the conductive roller is in contact with an adjacent member such as a photoconductor with the toner attached thereto. Here, if the conductive roller is highly contaminated with respect to the adjacent member such as the photoconductor, the toner adhered to the conductive roller is fused to the adjacent member such as the photoconductor to cause an image defect. This is because printing by the image forming apparatus is completed by fusing toner to a recording medium such as paper, so a binder having a low melting point is used, and the binder remains in the conductive roller, particularly in the elastic layer. This is because, when coexisting with a chemical substance such as a solvent component, toner fusion occurs even at a temperature below the melting point. Therefore, in the conductive roller, it is important that the solvent component and the uncured component contained in the elastic layer are as small as possible.

  For example, in JP-A-9-176269 (Patent Document 1), as an elastic material suitable for an elastic roller such as a developing roller and having good performance of photoreceptor contamination and residual distortion, Asker C hardness, compression set and An elastic member in which the amount of acetone extracted is defined is disclosed.

JP-A-9-176269

  However, when the present inventor examined, the elastic member disclosed in JP-A-9-176269 can be suitably used for a conductive roller having an elastic layer made of polyurethane foam. In the conductive roller having the elastic layer, since the components and composition necessary for curing are different from those of foam formation, it has been found that there is still room for improvement with respect to the contamination on adjacent members such as the photoreceptor.

  Accordingly, an object of the present invention is to provide a conductive roller that solves the above-described problems of the prior art and has an elastic layer made of an ultraviolet curable resin and can improve the contamination of adjacent members such as a photoreceptor. There is to do. Another object of the present invention is to provide an image forming apparatus capable of stably forming a good image by using such a conductive roller.

  As a result of intensive studies to achieve the above object, the present inventor has found that in the conductive roller having an elastic layer made of an ultraviolet curable resin disposed on the surface of the shaft member, the thickness of the elastic layer, Asker C hardness and acetone It has been found that by limiting the extraction amount to a specific range, the contamination of adjacent members such as a photoreceptor can be improved, and the present invention has been completed.

That is, the elastic roller of the present invention includes a shaft member and an elastic layer made of an ultraviolet curable resin disposed on the radially outer side of the shaft member,
The elastic layer has a thickness of 0.5 to 2 mm, an Asker C hardness of 70 degrees or less, and an acetone extraction amount of 7 mass% or less of the total mass of the ultraviolet curable resin. Here, “thickness” used in the present specification means an average thickness.

In the conductive roller of the present invention, the ultraviolet curable resin contains a urethane (meth) acrylate oligomer (A), a (meth) acrylate monomer (B), a photopolymerization initiator (C), and a conductive agent (D). The content of the urethane (meth) acrylate oligomer (A) in the total of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B) obtained by curing the elastic layer raw material by ultraviolet irradiation. Is 50 mass% or more.

  In the conductive roller of the present invention, the urethane (meth) acrylate oligomer (A) is obtained by adding a (meth) acrylate having a hydroxyl group to a urethane prepolymer composed of a polyol and a polyisocyanate. It is preferably at least one selected from the group consisting of polyoxypropylene glycol, polyoxyethylene glycol, polyoxytetramethylene glycol and polyoxybutylene glycol. In this case, the ultraviolet curable resin is hydrophobized, so that the contamination of adjacent members such as a photoreceptor can be improved.

  In the conductive roller of the present invention, the (meth) acrylate monomer (B) preferably has a functional group number of 3.0 or less. In this case, when the crosslinking density in the ultraviolet curable resin is appropriately increased, the contamination of adjacent members such as a photoreceptor can be improved.

In the conductive roller of the present invention, the (meth) acrylate monomer (B) is bifunctional.
Urethane (meth) acrylate oligomer (A) containing (meth) acrylate monomer
And the content of the bifunctional (meth) acrylate monomer in the total of the (meth) acrylate monomer (B) is 1 to 15% by mass . In this case, the amount of acetone extracted is reduced, and the contamination of adjacent members such as a photoconductor can be improved.

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

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

  According to the present invention, the surface of the shaft member has a specific thickness, Asker C hardness and acetone extraction amount, and has an elastic layer made of an ultraviolet curable resin, which improves the contamination of adjacent members such as a photoreceptor. An electrically conductive roller can be provided. Further, by using such a conductive roller, it is possible to provide an image forming apparatus capable of stably forming a good image.

<Conductive roller>
Below, the conductive roller of this invention is demonstrated in detail, referring a figure. FIG. 1 is a cross-sectional view of an example of a conductive roller of the present invention. The illustrated conductive roller 1 includes a shaft member 2 that is pivotally supported at both ends in the length direction, and an elastic layer 3 made of an ultraviolet curable resin that is disposed on the outer side in the radial direction of the shaft member 2. . 1 has the elastic layer 3 formed from only one layer, the conductive roller of the present invention may form the elastic layer from two or more layers. Moreover, the electroconductive roller of this invention can also have a coating-film layer on the surface of an elastic layer, as shown in FIG.

  FIG. 2 is a cross-sectional view of another example of the conductive roller of the present invention. The illustrated conductive roller 4 includes two coating film layers 5 arranged on the radially outer side of the elastic layer 3 made of an ultraviolet curable resin. The same reference numerals as those in FIG. 1 indicate the same members. Moreover, although the conductive roller 4 in the illustrated example has two coating film layers 5, the conductive roller of the present invention may have only one coating film layer or a coating film layer. May have three or more layers. In the conductive roller of the present invention, by disposing the coating film layer on the outer side in the radial direction of the elastic layer, it is possible to prevent bleeding of chemical substances that cause contamination remaining in the elastic layer. Further, additives such as fine particles can be appropriately selected and blended in the raw material of the coating film layer according to the performance of the surface layer of the conductive roller. The coating layer is not particularly limited, but preferably contains an ultraviolet curable resin from the viewpoint of adhesion to the elastic layer.

  1 and 2, the shaft member 2 includes 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 roller of the present invention. Is not particularly limited as long as it has good conductivity. For example, it may be composed only of the metal shaft 2A, may be composed only of a highly rigid resin base material, or is hollowed inside. It may be a cylindrical body made of metal or high-rigidity 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 high-rigidity 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 5 to 20 mm. 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 5 to 10 mm. In addition, even if the outer diameter of a shaft member is enlarged by using a resin material for the said shaft member, the increase in the mass of a shaft member can be suppressed.

  In the conductive roller of the present invention, the elastic layer made of the ultraviolet curable resin has a thickness of 0.5 to 2 mm, an Asker C hardness of 70 degrees or less, and an acetone extraction amount of 7 mass of the total mass of the ultraviolet curable resin. % Or less. As described above, in an image forming apparatus, toner is fused to an adjacent member such as a photosensitive member by a chemical substance such as a solvent component or an uncured component remaining in a conductive roller, particularly an elastic layer of the conductive roller. This contributes to the occurrence of image defects. The present inventor has examined in detail the contamination of adjacent members such as a photoreceptor, and in an elastic layer made of an ultraviolet curable resin having a specific thickness and Asker C hardness, the chemicals such as solvent components and uncured components are used. It was found that the contamination of adjacent members such as a photoreceptor can be sufficiently reduced by regulating the amount of acetone extracted from the substance to a certain value or less. Further, the elastic layer of the conductive roller of the present invention has an acetone extraction amount of 7% by mass or less of the total mass of the ultraviolet curable resin forming the elastic layer, thereby preventing contamination of adjacent members such as a photoconductor. Here, when a conductive roller having the elastic layer is used in an image forming apparatus, a good image can be stably formed without causing an image defect. In addition, since the conductive roller of the present invention has an elastic layer thickness of 0.5 to 2 mm and an Asker C hardness of 70 degrees or less, the elastic layer is made of shaft members such as roundness, runout, unevenness, etc. The occurrence of image unevenness can be significantly reduced when such a conductive roller is used in an image forming apparatus and hardly affected by surface accuracy.

  The elastic layer of the conductive roller of the present invention requires that the acetone extraction amount is 7% by mass or less of the total mass of the ultraviolet curable resin, and is preferably 0.1 to 3.5% by mass. Here, the amount of acetone extracted is the ratio (% by mass) of the extract contained in the ultraviolet curable resin when the ultraviolet curable resin forming the elastic layer is subjected to heat reflux extraction with acetone for 8 hours using a Soxhlet extraction apparatus. ). By setting the amount of acetone extracted to 7% by mass or less, the contamination with respect to adjacent members such as a photoreceptor can be greatly improved. In the conductive roller of the present invention, the amount of acetone extracted can be suppressed by reducing the content of low molecular weight compounds that can be contained in the elastic layer raw material. Becomes too high, and it becomes difficult to form an elastic layer. Therefore, the acetone extraction amount is preferably adjusted by appropriately selecting the components, compositions, etc. of the relatively high molecular weight compound (eg, oligomer) that can be contained in the elastic layer raw material.

  The elastic layer of the conductive roller of the present invention needs to have a thickness of 0.5 to 2 mm, preferably 0.5 to 1.2 mm. Here, if the thickness of the elastic layer is within the specified range, the influence caused by the surface accuracy of the shaft member can be effectively reduced. Further, if the thickness of the elastic layer is less than 0.5 mm, the influence due to the surface accuracy of the shaft member cannot be sufficiently mitigated. On the other hand, if the thickness exceeds 2 mm, formation of the elastic layer becomes difficult. In addition, when the electroconductive roller of this invention is provided with the coating-film layer arrange | positioned on the radial direction outer side of an elastic layer, it is preferable that the thickness of this coating-film layer is 5-50 micrometers.

  The elastic layer of the conductive roller of the present invention requires an Asker C hardness of 70 degrees or less, and preferably 35 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. By setting the Asker C hardness to 70 degrees or less, the influence caused by the surface accuracy of the shaft member can be sufficiently absorbed, and the occurrence of image unevenness can be significantly reduced. In addition, this Asker C hardness can be adjusted by selecting suitably the component, composition, etc. which are contained in the raw material for elastic layers.

  The elastic layer of the conductive roller of the present invention is made of an ultraviolet curable resin. For example, the urethane (meth) acrylate oligomer (A), the (meth) acrylate monomer (B), the photopolymerization initiator (C), and the conductive agent ( It comprises an ultraviolet curable resin obtained by curing the elastic layer material containing D) with ultraviolet irradiation. 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 (meth) acrylate oligomer (A) used for the elastic layer material has one or more acryloyloxy groups (CH ₂ ═CHCOO—) or methacryloyloxy groups (CH ₂ ═C (CH ₃ ) COO—). And a compound having a plurality of urethane bonds (—NHCOO—). The urethane (meth) acrylate oligomer (A) preferably has a functional group number of 3.0 or less, more preferably 1.5 to 2.5. Here, the functional group refers to an acryloyloxy group and a methacryloyloxy group, and the number of functional groups refers to the average number of functional groups. If the number of functional groups of the urethane (meth) acrylate oligomer (A) is 3.0 or less, the crosslinking density in the UV curable resin will increase moderately, reducing the amount of acetone extracted without increasing the hardness of the elastic layer can do. Moreover, when a trifunctional urethane (meth) acrylate oligomer is contained in the urethane (meth) acrylate oligomer (A), the hardness of the elastic layer may be increased.

  The urethane (meth) acrylate oligomer (A) preferably has a molecular weight of 5,000 to 100,000. The molecular weight is a number average molecular weight in terms of polystyrene. When the molecular weight of the urethane (meth) acrylate oligomer (A) is less than 5,000, the hardness of the elastic layer may be too high. On the other hand, when it exceeds 100,000, the compressive residual strain of the elastic layer may be too large.

  The urethane (meth) acrylate oligomer (A) is not particularly limited. For example, it is produced by synthesizing a urethane prepolymer from a polyol and a polyisocyanate and adding a (meth) acrylate having a hydroxyl group to the urethane prepolymer. can do.

  The polyol used for the synthesis of the urethane prepolymer is a compound having a plurality of hydroxyl groups (OH groups). Specific examples of the polyol include polyether polyol, polyester polyol, polytetramethylene glycol, polybutadiene polyol, and alkylene oxide modification. Examples thereof include polybutadiene polyol and polyisoprene polyol, and among these, polyether polyol is particularly preferable. Specific examples of the polyether polyol include polyoxypropylene glycol, polyoxyethylene glycol, polyoxymethylene glycol, polyoxytetramethylene glycol, and polyoxybutylene glycol. When such a suitable polyether polyol is selected as the polyol used for the synthesis of the urethane prepolymer, the hydrophobicity of the resulting UV curable resin is increased, making it difficult to incorporate moisture into the UV curable resin. An effect is obtained. For this reason, this ultraviolet curable resin shows tolerance with respect to degradation reactions, such as a hydrolysis, and can reduce the amount of acetone extraction. 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. These polyols may be used alone or in a blend of two or more.

  The polyol used for the synthesis of the urethane prepolymer preferably has a molecular weight in the range of 500 to 15,000. If the molecular weight of the polyol used for the synthesis of the urethane prepolymer is less than 500, the hardness becomes high, so that it is not suitable for the elastic layer of the conductive roller.On the other hand, if it exceeds 15,000, the compressive residual strain increases, resulting in poor image quality. It tends to occur.

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

In the synthesis of the urethane prepolymer, the ratio of the polyol and the polyisocyanate can be appropriately selected according to the purpose. Here, the urethane prepolymer preferably has an isocyanate index in the range of 110 to 200, and more preferably in the range of 115 to 200. The isocyanate index is the following formula:
(Isocyanate index) = (B / A) × 100
[Wherein, A is the number of OH groups of the polyol, and B is the number of NCO groups of the polyisocyanate]. If the isocyanate index of the urethane prepolymer is less than 110, the compression residual strain increases and image defects are liable to occur. On the other hand, if it exceeds 200, the isocyanate that does not react with the polyol increases and the physical properties deteriorate.

  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 and 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 (meth) acrylate having a hydroxyl group to be added to the urethane prepolymer has one or more hydroxyl groups, and is an acryloyloxy group (CH ₂ ═CHCOO—) or a methacryloyloxy group (CH ₂ ═C (CH ₃ ) COO. It is a compound having one or more-). The (meth) acrylate having a hydroxyl group can be added to the isocyanate group of the urethane prepolymer. Examples of the (meth) acrylate having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and the like. These acrylates having a hydroxyl group may be used alone or in combination of two or more.

The (meth) acrylate monomer (B) used for the elastic layer raw material is a monomer having one or more acryloyloxy groups (CH ₂ ═CHCOO—) or methacryloyloxy groups (CH ₂ ═C (CH ₃ ) COO—). Yes, it acts as a reactive diluent, that is, it can be cured with ultraviolet rays, and the viscosity of the elastic layer material can be lowered.

  The (meth) acrylate monomer (B) preferably has a functional group number of 3.0 or less, and more preferably 1-2. Here, the functional group refers to an acryloyloxy group and a methacryloyloxy group, and the number of functional groups refers to the average number of functional groups. If the number of functional groups in the (meth) acrylate monomer (B) is 3.0 or less, the crosslinking density in the UV curable resin will increase moderately, so that the acetone extraction amount can be reduced without increasing the hardness of the elastic layer. Can do. When the (meth) acrylate monomer (B) contains a bifunctional (meth) acrylate monomer, 2 in the total of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B). The content of the functional (meth) acrylate monomer is preferably 1 to 15 masses. If the content of the bifunctional (meth) acrylate monomer is less than 1% by mass, the crosslinking density in the UV curable resin cannot be increased sufficiently. On the other hand, if the content exceeds 15% by mass, the crosslinking density increases. In some cases, the hardness of the elastic layer may be increased.

  The (meth) acrylate monomer (B) preferably has a glass transition point (Tg) of 50 ° C. or lower. Here, the (meth) acrylate monomer (B) having a glass transition point (Tg) of 50 ° C. or less generally has a large proportion of the portion excluding the functional group in the monomer molecule, and the (meth) acrylate monomer In the case where (B) is polymerized with the above oligomer (A), the movement of the polymer excluding the functional group of the (meth) acrylate monomer (B) increases, and as a result, the hardness of the elastic layer is increased. Reduce.

  Examples of the (meth) acrylate monomer (B) include lauryl (meth) acrylate, isomyristyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, triethylene glycol di (meth) acrylate, β- (meth) acryloyloxy Ethyl hydrogen succinate, isobornyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, n-butyl (meth) acrylate, isoamyl (meth) acrylate, glycidyl (meth) acrylate, butoxyethyl (meth) acrylate , Ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate Over doors and the like. These (meth) acrylate monomers (B) may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the elastic layer raw material, the ratio of the urethane (meth) acrylate oligomer (A) to the total of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B) is 50% by mass or more. Preferably, it is 60-90 mass%. When the content of the urethane (meth) acrylate oligomer (A) is less than 50% by mass, the proportion of the monomer is increased, so that the low molecular weight polymer is increased, and as a result, the acetone extraction amount may be increased.

  In the elastic layer raw material, the mass ratio (A / B) of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B) is preferably in the range of 100/0 to 10/90. . By setting the ratio of the urethane (meth) acrylate oligomer (A) in the total of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B) to 10% by mass or more (that is, (meth) acrylate By setting the ratio of the monomer (B) to 90% by mass or less, an elastic layer having a low hardness can be obtained.

  The photopolymerization initiator (C) used for the elastic layer raw material has an action of initiating polymerization of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B) described above when irradiated with ultraviolet rays. Have Examples of the photopolymerization initiator (C) 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. In addition, the compounding quantity of the photoinitiator (C) in the said raw material for elastic layers is with respect to a total of 100 mass parts of the said urethane (meth) acrylate oligomer (A) and the said (meth) acrylate monomer (B). The range of 0.2 to 5.0 parts by mass is preferable.

  The conductive agent (D) used as the elastic layer material has a function of imparting conductivity to the elastic layer. As this electrically conductive agent (D), 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 (meth) acrylate oligomer (A) and has transparency, when the ionic conductive agent is used as the conductive agent (D), the elastic layer material is formed on the shaft member. Even if it is thickly applied, 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. In addition, the compounding quantity of the electrically conductive agent (D) in the said raw material for elastic layers is 0.1 with respect to a total of 100 mass parts of the said urethane (meth) acrylate oligomer (A) and the said (meth) acrylate monomer (B). A range of ˜5.0 parts by mass is preferred.

  In addition, a polymerization inhibitor is added to the elastic layer raw material in an amount of 0.001 to 0.2 parts by mass with respect to a total of 100 parts by mass of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B). May be. 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 conductive 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 curing it by ultraviolet irradiation. Therefore, the conductive 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, a die coating method, and the like. Among these methods, the die coating method is preferable. When forming the elastic layer, applying the elastic layer raw material by a die coating method achieves quick and reliable application of the elastic layer raw material, and greatly reduces the work efficiency of manufacturing the conductive roller. be able to. 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 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 feeding roller, a cleaning roller, a fixing pressure roller, etc. in an image forming apparatus. It is particularly suitable as a roller.

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

  Hereinafter, the image forming apparatus of the present invention will be described in detail with reference to FIG. FIG. 3 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 6 holding an electrostatic latent image, a charging roller 7 that is positioned in the vicinity (upward in the drawing) of the photosensitive member 6 and charges the photosensitive member 6, and toner 8. A toner supply roller 9, a developing roller 10 disposed between the toner supply roller 9 and the photosensitive member 6, a stratifying blade 11 provided in the vicinity of the developing roller 10 (upward in the drawing), and a photosensitive member. 6 is provided with a transfer roller 12 located in the vicinity (lower in the drawing) 6 and a cleaning roller 13 disposed adjacent to the photoreceptor 6. The image forming apparatus of the present invention can further include known components (not shown) that are normally used in the image forming apparatus.

  In the illustrated image forming apparatus, the charging roller 7 is brought into contact with the photosensitive member 6 and a voltage is applied between the photosensitive member 6 and the charging roller 7 to charge the photosensitive member 6 to a constant potential. Then, an electrostatic latent image is formed on the photoreceptor 6 by an exposure machine (not shown). Next, the photosensitive member 6, the toner supply roller 9, and the developing roller 10 rotate in the direction of the arrow in the drawing, so that the toner 8 on the toner supply roller 9 is sent to the photosensitive member 6 through the developing roller 10. It is done. The toner 8 on the developing roller 10 is adjusted to a uniform thin layer by the stratifying blade 11 and rotates while the developing roller 10 and the photosensitive member 6 are in contact with each other, so that the toner 8 is transferred from the developing roller 10 to the photosensitive member 6. It adheres to the electrostatic latent image and the latent image becomes visible. The toner 8 attached to the latent image is transferred to a recording medium such as paper by the transfer roller 12, and the toner 8 remaining on the photosensitive member 6 after the transfer is removed by the cleaning roller 13. Here, in the image forming apparatus of the present invention, at least one of the charging roller 7, the toner supply roller 9, the developing roller 10, the transfer roller 12, and the cleaning roller 13, preferably the developing roller 10, the above-described present invention. By using the conductive roller, excellent images can be stably formed.

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. Here, the following Examples 1 to 7 and 14 to 15 correspond to reference examples.

<Synthesis of oligomer (A-1)>
While stirring and mixing 100 parts of polyoxypropylene glycol with a molecular weight of 3200 and 100 parts by weight of polyoxypropylene glycol, 10.4 parts by weight of isophorone diisocyanate (isocyanate index = 150) and 0.01 parts by weight of dibutyltin dilaurate, the reaction is carried out at 70 ° C. for 2 hours. A urethane prepolymer having isocyanate groups at both ends was synthesized. The obtained urethane prepolymer had an NCO group content of 1.19%. Further, 3.3 parts by mass of 2-hydroxyethyl acrylate (HEA) was mixed with 100 parts by mass of this urethane prepolymer and reacted at 70 ° C. for 2 hours to give an oligomer (A-1) having 2 functional groups and a molecular weight of 18000. ) Was synthesized.

<Synthesis of oligomer (A-2)>
The number of functional groups is 2 and the molecular weight is the same as in the above oligomer (A-1), except that a bifunctional polyoxyethylene glycol having a molecular weight of 4000 is used in place of the bifunctional polyoxypropylene glycol having a molecular weight of 3200. 18000 oligomers (A-2) were synthesized.

<Synthesis of oligomer (A-3)>
Similar to the above oligomer (A-1), except that a bifunctional polyoxypropylene glycol having a molecular weight of 3200 was used instead of a bifunctional polyoxypropylene glycol having a molecular weight of 4000, the number of functional groups was 2 and the molecular weight was the same. Oligomer (A-3) having a molecular weight of 20000 was synthesized.

<Synthesis of oligomer (A-4)>
The number of functional groups is 2 and the molecular weight is the same as the oligomer (A-1) except that a bifunctional polyoxybutylene glycol having a molecular weight of 4000 is used instead of the bifunctional polyoxypropylene glycol having a molecular weight of 3200. 18000 oligomers (A-4) were synthesized.

<Examples 1-20 and Comparative Examples 1-2>
The raw material mixture having the formulation shown in Tables 1 to 3 was stirred and mixed with a stirrer at a liquid temperature of 70 ° C. and 60 rpm for 1 hour, and the mixed solution was filtered to obtain an elastic layer coating solution.

The elastic layer coating solution is irradiated with UV at an irradiation intensity of 700 mW / cm ² for 2.5 seconds to produce a 1.0 mm thick sheet sample, and then cut into a 1 cm square size, soxhlet extraction About 5 g was weighed on a filter paper for tubes. Next, after adding 150 ml of acetone to a 150 ml round bottom flask, attach a Soxhlet extraction tube and a Dimroth tube containing filter paper with a sample to the round bottom flask, and heat in a 70 ° C. water bath for 8 hours. Reflux extraction was performed. Thereafter, acetone in the round bottom flask was distilled off under reduced pressure and dried in an oven at 80 ° C. for 4 hours, and the amount of acetone extracted was determined. The results are shown in Tables 1-3. In addition, the amount of acetone extraction is the following formula:
Acetone extraction amount (% by mass) = [(C−B) / A] × 100
[In the formula, A is the mass (g) of the sample weighed on the filter paper for Soxhlet extraction tube, B is the mass (g) of the 150 ml round bottom flask, and C is the mass of the 150 ml round bottom flask containing the extract. (G) is a value calculated by].

The elastic layer coating solution 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 irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 10 seconds to form a cylindrical shape. A UV curable resin sample for measuring physical properties was obtained. About the obtained sample, the Asker C hardness [manufactured by Kobunshi Keiki Co., Ltd.] of the plane portion was measured. The results are shown in Tables 1-3.

Next, the elastic layer coating liquid was 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 was inserted with a thickness of 1500 μm using a die coater. The elastic layer coating solution was cured by spot UV irradiation while coating. 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, an intermediate layer coating solution having the formulation shown in Table 4 was applied with a roll coater, and irradiated with UV to produce a roller with an intermediate layer (intermediate layer) Layer: 7 μm). Next, a surface layer coating solution having the formulation shown in Table 4 was applied to the surface of the intermediate layer roller with a roll coater and irradiated with UV to obtain a conductive roller (surface layer: 8 μm). About the obtained electroconductive roller, the contamination test was evaluated by the following method. The results are shown in Tables 1-3.

(1) Contamination test The above conductive roller is incorporated as a developing roller into a toner cartridge in an image forming apparatus, left at 50 ° C. for 5 days, printed, and a horizontal stripe that applies to the roller pitch is visually evaluated by sensory evaluation. What was observed was “NG”, and what was not observed was “OK”.

* 1 Hydrophobic monofunctional monomer, lauryl acrylate, manufactured by Kyoeisha Chemical Co., Ltd., Tg = -3 ° C.
* 2 Hydrophobic monofunctional monomer, isomyristyl acrylate, manufactured by Kyoeisha Chemical Co., Ltd., Tg = -56 ° C.
* 3 Hydrophilic monofunctional monomer, methoxytriethylene glycol acrylate, manufactured by Kyoeisha Chemical Co., Ltd., Tg = -60 ° C.
* 4 Bifunctional monomer, triethylene glycol diacrylate, manufactured by Kyoeisha Chemical Co., Ltd., Tg = 80 ° C.
* 5 Hydrophilic monofunctional monomer, β-acryloyloxyethyl hydrogen succinate, manufactured by Shin-Nakamura Chemical Co., Ltd., Tg = -10 ° C.
* 6 Made by Ciba Specialty Chemicals.
* 7 Made by Akishima Chemical Co., Ltd.
* 8 Monofunctional monomer, isobornyl acrylate, manufactured by Kyoeisha Chemical Co., Ltd.
* 9 Bifunctional monomer, # 600 diacrylate, manufactured by Kyoeisha Chemical Co., Ltd.

* 10 Urethane acrylate oligomer, manufactured by Nippon Synthetic Chemical Industry.
* 11 Morpholine acrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.
* 12 Isobornyl acrylate, manufactured by Kyoeisha Chemical Co., Ltd.
* 13 2-Butyl-2-ethyl-1,3-propanediol diacrylate, manufactured by Kyoeisha Chemical Co., Ltd.
* 14 Urethane urea resin, manufactured by Dainippon Ink Co., Ltd.
* 15 Acrylic resin manufactured by Soken Chemical Co., Ltd.
* 16 Made by Ciba Specialty Chemicals.

  From Tables 1 to 3, the conductive roller of the example has an elastic layer thickness of 0.5 to 2 mm, an Asker C hardness of 70 degrees or less, and an acetone extraction amount of 7 mass% or less of the total mass of the ultraviolet curable resin. Therefore, in the image forming apparatus in which the conductive roller is incorporated as a developing roller, it can be seen that contamination of adjacent members such as a photoconductor is not confirmed, and occurrence of image defects is suppressed.

It is sectional drawing of an example of the electroconductive roller of this invention. It is sectional drawing of the other example of the electroconductive 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 roller 2 Shaft member 2A Metal shaft 2B High-rigidity resin base material 3 Elastic layer 4 Conductive roller 5 Coating layer 6 Photoreceptor 7 Charging roller 8 Toner 9 Toner supply roller 10 Developing roller 11 Layering blade 12 Transfer roller 13 Cleaning roller

Claims (6)

In a conductive roller comprising a shaft member and an elastic layer made of an ultraviolet curable resin disposed on the outer side in the radial direction of the shaft member,
Said elastic layer has a thickness of 0.5 to 2 mm, Asker C hardness der and acetone extraction amount is less than 7 wt% of the ultraviolet curable resin to the total weight below 70 degrees is,
The ultraviolet curable resin cures the elastic layer material containing the urethane (meth) acrylate oligomer (A), the (meth) acrylate monomer (B), the photopolymerization initiator (C) and the conductive agent (D) by ultraviolet irradiation. Being
The content of the urethane (meth) acrylate oligomer (A) in the total of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B) is 50% by mass or more,
The (meth) acrylate monomer (B) contains a bifunctional (meth) acrylate monomer, and the bifunctional in the total of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B). A conductive roller having a (meth) acrylate monomer content of 1 to 15% by mass. The content of the bifunctional (meth) acrylate monomer in the total of the urethane (meth) acrylate oligomer (A) and the (meth) acrylate monomer (B) is 10 to 15% by mass. Item 2. The conductive roller according to Item 1. The urethane (meth) acrylate oligomer (A) is obtained by adding a (meth) acrylate having a hydroxyl group to a urethane prepolymer composed of a polyol and a polyisocyanate,
The conductive property according to claim 1 or 2 , wherein the polyol is at least one selected from the group consisting of polyoxypropylene glycol, polyoxyethylene glycol, polyoxytetramethylene glycol, and polyoxybutylene glycol. roller. The conductive roller according to claim 1, wherein the (meth) acrylate monomer (B) has a functional group number of 3.0 or less. Conductive roller according to any one of claims 1-4, characterized in that development is a roller. An image forming apparatus using a conductive roller according to any one of claims 1-5.

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