JP5781780B2 - Developing roller - Google Patents

Description

  The present invention relates to a developing roller (hereinafter also simply referred to as “roller”), and more particularly to a developing roller used in an image forming process in an image forming apparatus such as a copying machine or a printer.

  Conventionally, as a developing method when a non-magnetic one-component developer is used as a developer (toner), toner is supplied to an image carrier such as a photosensitive drum holding an electrostatic latent image via a developing roller, and an image is obtained. A development method (pressure development method) is known in which a latent image is visualized by attaching toner to the latent image on the carrier. In this developing method, development is performed by bringing a developing roller carrying toner into contact with an image carrier holding an electrostatic latent image and attaching the toner to the latent image on the image carrier. The developing roller to be used needs to be formed of an elastic body having conductivity.

  FIG. 2 shows a configuration example of a developing device using a pressure developing method. In the illustrated developing device, a developing roller 10 is disposed in contact with a photosensitive drum 12 between a toner supply roller 11 for supplying toner and a photosensitive drum 12 holding an electrostatic latent image. As the developing roller 10, the photosensitive drum 12, and the toner supply roller 11 rotate in the directions of the arrows in the drawing, the toner 13 is supplied to the surface of the developing roller 10 by the toner supply roller 11. The supplied toner is adjusted to a uniform thin layer by the stratifying blade 14, and the developing roller 10 rotates in contact with the photosensitive drum 12 in this state, whereby the toner formed in the thin layer is transferred from the developing roller 10 to the photosensitive drum. The latent image is visualized by attaching to the 12 latent images. Note that reference numeral 15 in the drawing denotes a transfer portion, where a toner image is transferred to a recording medium such as paper. Reference numeral 16 denotes a cleaning unit, and toner remaining on the surface of the photosensitive drum 12 after transfer is removed by a cleaning blade 17.

  By the way, in the case where the developing roller is composed of three layers of an elastic layer, an intermediate layer, and a surface layer sequentially formed on the outer periphery of the shaft, the resistance of the intermediate layer is designed to be low so that the environmental variation of the resistance value It is known that the print quality can be improved by decreasing the number. Therefore, in order to reduce the resistance value of the intermediate layer, it is generally performed to add carbon black to the intermediate layer. On the other hand, as the resin component constituting the intermediate layer, conventionally, a thermosetting resin or a thermoplastic resin has been used. For example, in a thermosetting resin, a large amount of heat and a lot of time are required for curing. It was necessary and was not sufficient in terms of environmental performance and production efficiency.

  On the other hand, for example, in Patent Document 1, at least one of the one or more elastic layers disposed on the radially outer side of the shaft member is made of an ultraviolet curable resin containing a conductive agent and an ultraviolet polymerization initiator. A conductive roller is disclosed. In Patent Document 1, in an example using carbon black as a conductive agent for the elastic layer, the elastic layer is cured by irradiating an electron beam (EB) instead of UV light. Patent Document 2 includes a shaft, a non-foamed elastic layer formed on the outer periphery thereof, and at least one resin coating layer formed on the outer peripheral surface thereof. A developing roller made of an ultraviolet curable resin is disclosed.

Republication 2006-109563 (Claims etc.) JP 2004-240389 A (Claims etc.)

  If an ultraviolet (UV) curable resin is used as the resin constituting the intermediate layer as in the technique disclosed in Patent Document 1, it can be cured in a short light irradiation time of about several seconds when the layer is formed. Compared to the case where a functional resin is used, it is superior in terms of energy efficiency and productivity. However, when a UV curable resin is used for the intermediate layer and carbon black is added to the intermediate layer in order to reduce resistance, the carbon black absorbs the UV light irradiated when the resin is cured, There was a problem that UV light could not reach the inside of the layer, resulting in poor curing of the intermediate layer. On the other hand, for example, Patent Document 2 discloses an example in which a layer containing a UV curable resin and carbon black is cured by UV light. In this example, the conductivity of carbon black is also disclosed. Sufficient addition amount is not used for expression.

  Although it is conceivable to increase the amount of the photopolymerization initiator against the occurrence of poor curing of the intermediate layer, the photopolymerization initiator absorbs UV light and proceeds with the curing reaction. When the amount of the photopolymerization initiator is increased, the UV light is prevented from reaching the inside of the layer. Thus, there has been no means that can reliably prevent the occurrence of poor curing in a layer in which carbon black is added to a UV curable resin. Therefore, conventionally, an ionic conductive agent has been added to the UV curable resin to lower the resistance, but the resistance value obtained has a limit.

  Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a sufficiently low resistance in the intermediate layer without causing problems such as peeling of the coating film due to poor curing of the intermediate layer containing UV curable resin and carbon black. It is an object of the present invention to provide a developing roller with improved printing quality by realizing the value and reducing the environmental variation of the resistance value of the roller.

  As a result of intensive studies, the present inventors have found the following. That is, the photopolymerization initiator used for curing the UV curable resin has different wavelengths of light to be absorbed depending on the type. Therefore, in order to efficiently absorb the light of a specific wavelength emitted from the light source and cure the resin, it is considered effective to use a plurality of photopolymerization initiators having different wavelengths of light to be absorbed. .

  From such a viewpoint, as a result of further studies, the present inventors have found that the above problem can be solved by using a specific combination of plural kinds as a photopolymerization initiator to be blended in the intermediate layer together with the UV curable resin and carbon black. As a result, the present invention has been completed.

That is, the present invention provides a developing roller comprising an elastic layer, an intermediate layer, and a surface layer in order on the outer periphery of the shaft.
The intermediate layer contains 1 part by mass or more of carbon black with respect to 100 parts by mass of the ultraviolet curable resin, and further has a photopolymerization initiator having an extinction coefficient at 254 nm of 2 × 10 ⁴ ml / g · cm or more. Containing 5 to ² parts by mass and 0.5 to 2 parts by mass of a photopolymerization initiator having an extinction coefficient at 365 nm of 4 × 10 ² ml / g · cm or more,
The composition used for forming the surface layer contains a urethane (meth) acrylate oligomer obtained by reacting a polybutadiene polyol or hydrogenated polybutadiene polyol, a polyisocyanate, and a (meth) acrylate having a hydroxyl group. Is.

In the developing roller of the present invention, it is preferable that the elastic layer contains an ultraviolet curable resin and an ionic conductive agent. The resistance value under the conditions of a temperature of 10 ° C. and a humidity of 15% RH is preferably 10 ⁴ to 10 ⁸ Ω.

  According to the present invention, the above configuration achieves a sufficiently low resistance value in the intermediate layer without causing problems such as peeling of the coating film due to poor curing of the intermediate layer, and the resistance value of the roller. By reducing environmental fluctuations, it became possible to realize a developing roller with improved print quality.

FIG. 3 is a longitudinal sectional view according to an example of the developing roller of the present invention. It is a schematic explanatory drawing which shows one structural example of the image development apparatus using a pressure development method.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view according to an example of the developing roller of the present invention. As shown in the figure, the developing roller 10 of the present invention is formed by sequentially laminating an elastic layer 2, an intermediate layer 3 and a surface layer 4 on the outer periphery of the shaft 1.

In the present invention, the intermediate layer 3 comprises an ultraviolet (UV) curable resin, carbon black, a photopolymerization initiator having an extinction coefficient at 254 nm of 2 × 10 ⁴ ml / g · cm or more, and absorbance at 365 nm. It is important to contain a photopolymerization initiator having a coefficient of 4 × 10 ² ml / g · cm or more. By including a plurality of photopolymerization initiators having different wavelengths of light to be absorbed in the intermediate layer 3 using a UV curable resin, it is possible to absorb the light of a plurality of wavelengths and advance the curing reaction, Even when carbon black is contained in a predetermined amount or more as a conductive agent, it is possible to efficiently absorb the light emitted from the light source and complete the UV curing of the resin. This makes it possible to use carbon black as the conductive agent of the intermediate layer 3, so that the resistance value of the roller in a low-temperature and low-humidity environment cannot be obtained only with an ionic conductive agent. 10 ⁴ to 10 ⁸ Ω A low resistance value of about a degree could be achieved. In addition, since carbon black can be used, there is almost no characteristic increase in resistance at low humidity when an ionic conductive agent is used, and the problem of deterioration in print quality due to environmental fluctuations can be solved.

In the present invention, the problem of the photopolymerization initiator having a high extinction coefficient at 254 nm and the photopolymerization initiator having a high extinction coefficient at 365 nm is that these 254 nm and 365 nm are the main in a general UV light source. This is because the emission wavelength. In addition, a photopolymerization initiator having an extinction coefficient at 254 nm of 2 × 10 ⁴ ml / g · cm or more and an extinction coefficient at 365 nm of 4 × 10 ² ml / g · cm or more is used because the extinction coefficient is This is because if it is lower than this, curing failure cannot be sufficiently prevented. Examples of the photopolymerization initiator having an extinction coefficient at 254 nm of 2 × 10 ⁴ ml / g · cm or more include IRGACURE 651, 184, 500, 2959, 127, 1800, 784, DAROCUR 1173, 4265 (both are BASF Japan Ltd. )) And the like. Examples of the photopolymerization initiator having an extinction coefficient at 365 nm of 4 × 10 ² ml / g · cm or more include IRGACURE 907, 369, 379, 819, 1800, 784, DAROCUR 4265, TPO (all of which are BASF Japan )) And the like.

  The blending amount of these two kinds of photopolymerization initiators in the intermediate layer forming composition is 0.2 to 5.0 parts by mass, particularly 0.5 to 2 parts per 100 parts by mass of the UV curable resin. A range of parts by mass is preferred.

  In the present invention, the UV curable resin used for the intermediate layer 3 is not particularly limited, and includes, for example, (A) urethane (meth) acrylate oligomer and (B) (meth) acrylate monomer. Can be suitably used.

The (A) urethane (meth) acrylate oligomer has one or more acryloyloxy groups (CH ₂ ═CHCOO—) or methacryloyloxy groups (CH ₂ ═C (CH ₃ ) COO—), and a urethane bond (—NHCOO). A compound having a plurality of-). This (A) urethane (meth) acrylate oligomer has a functional group number of 3.0 or less, particularly 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. (A) If the number of functional groups of the urethane (meth) acrylate oligomer is 3.0 or less, the crosslinking density in the UV curable resin will increase moderately, so the amount of acetone extracted is reduced without increasing the layer hardness. The effect of improving the contamination of adjacent members such as a photoconductor can be obtained. In addition, when a trifunctional urethane (meth) acrylate oligomer is contained in the (A) urethane (meth) acrylate oligomer, the hardness of the layer may be increased.

  (A) The urethane (meth) acrylate oligomer is preferably 5,000 to 100,000 in terms of polystyrene-equivalent number average molecular weight. (A) If the molecular weight of the urethane (meth) acrylate oligomer is less than 5,000, the hardness of the layer may be too high, while if it exceeds 100,000, the compressive residual strain of the layer may be too high. .

  Although it does not restrict | limit especially as said (A) urethane (meth) acrylate oligomer, For example, by synthesize | combining a urethane prepolymer from a polyol and polyisocyanate, and adding the (meth) acrylate which has a hydroxyl group to this urethane prepolymer. What was manufactured can be used conveniently.

  The polyol used for the synthesis of the urethane prepolymer is a compound having a plurality of hydroxyl groups (OH groups). Specific examples of such polyol include polyether polyol, polyester polyol, polytetramethylene glycol, polybutadiene polyol, alkylene oxide-modified polybutadiene polyol, and polyisoprene polyol. 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. By selecting these suitable polyether polyols as the polyol used for the synthesis of the urethane prepolymer, the effect of increasing the hydrophobicity of the layer and making it difficult to incorporate moisture into the layer can be obtained. For this reason, the layer exhibits resistance to degradation reactions such as hydrolysis, and the amount of acetone extracted can be reduced. As a result, the effect of improving the contamination of adjacent members such as a photoreceptor can be obtained. 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 becomes unsuitable for the layer of the developing roller. On the other hand, if it exceeds 15,000, the compressive residual strain increases, resulting in image defects. It tends to occur.

  The polyisocyanate used for the synthesis of the urethane prepolymer is a compound having a plurality of isocyanate groups (NCO groups). Specific examples of such polyisocyanates include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude diphenylmethane diisocyanate (crude MDI), isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, hexamethylene. Examples thereof include 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 a value calculated by (B / A) × 100, where A is the number of OH groups in the polyol and B is the number of NCO groups in the polyisocyanate. If the isocyanate index of the urethane prepolymer is less than 110, the compression residual strain increases and image defects are likely 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, pentamethyldipropylene Triamines such as triamine and tetramethylguanidine; triethylenediamine, dimethylpiperazine, methylethylpiperazine, methylmorpholine, Cyclic amines such as methylaminoethylmorpholine, 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, sodium hydroxide; tita such as tetrabutyl titanate, tetraethyl titanate, tetraisopropyl titanate Compounds; bismuth 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 such 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 and 2-hydroxypropyl (meth) acrylate. These acrylates having a hydroxyl group may be used alone or in combination of two or more.

The (B) (meth) acrylate monomer is a monomer having one or more acryloyloxy groups (CH ₂ ═CHCOO—) or methacryloyloxy groups (CH ₂ ═C (CH ₃ ) COO—). This (B) (meth) acrylate monomer acts as a reactive diluent, that is, it can be cured with UV and the viscosity of the intermediate layer forming composition can be lowered.

  The (B) (meth) acrylate monomer preferably has a functional group number of 3.0 or less, 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. (B) If the number of functional groups of the (meth) acrylate monomer is 3.0 or less, the crosslinking density in the UV curable resin will increase moderately, so that the amount of acetone extracted is reduced without increasing the hardness of the layer. And the effect of improving the contamination of adjacent members such as a photoconductor can be obtained. Moreover, when the said (B) (meth) acrylate monomer contains a bifunctional (meth) acrylate monomer, bifunctional in the sum total of the said urethane (meth) acrylate oligomer (A) and (meth) acrylate monomer (B). The content of the (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 it exceeds 15% by mass, the crosslinking density increases. This may increase the hardness of the layer.

  The (B) (meth) acrylate monomer preferably has a glass transition point (Tg) of 50 ° C. or lower. Here, the (B) (meth) acrylate monomer 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 (B) (meth) When the acrylate monomer is polymerized with the (A) urethane (meth) acrylate oligomer, the movement of the polymer excluding the functional group of the (B) (meth) acrylate monomer increases, resulting in layer hardness. Reduce.

  Examples of the (B) (meth) acrylate monomer include lauryl (meth) acrylate, isomyristyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, triethylene glycol di (meth) acrylate, and 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. These (B) (meth) acrylate monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the present invention, the proportion of the (A) urethane (meth) acrylate oligomer in the total amount of the (A) urethane (meth) acrylate oligomer and the (B) (meth) acrylate monomer is preferably 50% by mass or more. Preferably it is 60-90 mass%. (A) If the content rate of a urethane (meth) acrylate oligomer is less than 50 mass%, since the ratio of a monomer will increase, a low molecular weight polymer will increase, As a result, there exists a possibility that acetone extraction amount may increase.

  Carbon black used for the intermediate layer 3 includes conductive carbon black such as ketjen black and acetylene black, carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT and MT, and oxidized carbon black. Examples thereof include carbon black for ink and pyrolytic carbon black. The blending amount of such carbon black is 1 part by mass or more with respect to a total of 100 parts by mass of (A) urethane (meth) acrylate oligomer and (B) (meth) acrylate monomer constituting the UV curable resin. Is essential, and is preferably in the range of 2 to 15 parts by mass, more preferably 2 to 6 parts by mass. In the present invention, by blending carbon black in an amount in the above range, the resistance value of the intermediate layer 3 can be reduced, and a desired resistance value can be obtained for the entire roller, and the roller resistance associated with environmental changes can be obtained. The effect of suppressing fluctuation is obtained. However, if the amount of carbon black is too large, the intermediate layer 3 may be poorly cured.

  The intermediate layer forming composition further includes a polymerization inhibitor in a total of 100 parts by mass of the (A) urethane (meth) acrylate oligomer and the (B) (meth) acrylate monomer constituting the UV curable resin. On the other hand, you may add in 0.001-0.2 mass part. By adding a polymerization inhibitor, thermal polymerization before ultraviolet irradiation can be prevented. Such polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, p-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-p-cresol, butylhydroxyanisole, Examples include 3-hydroxythiophenol, α-nitroso-β-naphthol, p-benzoquinone, 2,5-dihydroxy-p-quinone and the like.

  Furthermore, in addition to the above, various known additives can be blended in the intermediate layer forming composition as long as the desired effects of the present invention are not impaired. In the present invention, the thickness of the intermediate layer 3 is preferably 1 to 10 μm.

  Next, the elastic layer 2 in the roller of the present invention can be formed of an elastic layer forming composition containing a UV curable resin, a photopolymerization initiator, and an ionic conductive agent. The UV curable resin may be the same as that used for the elastic layer, and is not particularly limited.

  The photoinitiator used for the elastic layer 2 has the effect | action which starts superposition | polymerization of the said (A) urethane (meth) acrylate oligomer and (B) (meth) acrylate monomer by irradiating with an ultraviolet-ray. Such photopolymerization initiators include 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, 2,2-dimethoxy-2-phenylacetophenone, acetophenone diethyl ketal, alkoxyacetophenone, benzyldimethyl ketal, benzophenone and 3,3. -Benzyl derivatives such as dimethyl-4-methoxybenzophenone, 4,4-dimethoxybenzophenone, 4,4-diaminobenzophenone, alkyl benzoylbenzoate, bis (4-dialkylaminophenyl) ketone, benzyl and benzylmethyl ketal Benzoin derivatives such as benzoin and benzoin isobutyl ether, benzoin isopropyl ether, 2-hydroxy-2-methylpropiophenone, 1-hydroxysilane Rohexyl phenyl ketone, xanthone, 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. are mentioned. Specific examples include IRGACURE 651, 184, 500, 2959, 127, 1800, 784, 907, 369, 379, 819, DAROCUR 1173, 4265, TPO (all manufactured by BASF Japan Ltd.) and the like. These photopolymerization initiators may be used alone or in combination of two or more. In addition, the compounding quantity of the photoinitiator in the composition for elastic layer formation is 100 mass in total of the said (A) urethane (meth) acrylate oligomer which comprises UV curable resin, and the said (B) (meth) acrylate monomer. A range of 0.2 to 5.0 parts by mass, particularly 0.5 to 2 parts by mass is preferable with respect to parts.

  The ionic conductive agent used for the elastic layer 2 has a function of imparting conductivity to the elastic layer. In addition to being dissolved in the (A) urethane (meth) acrylate oligomer, the ionic conductive agent has transparency, so even if the elastic layer forming composition is applied thickly on the shaft, the ultraviolet rays are sufficiently inside the coating film. And the elastic layer forming composition can be sufficiently cured. Examples of the ionic conductive agent include perchlorates, chlorates, hydrochlorides, bromates such as tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, and modified fatty acid dimethylethylammonium. 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.

  Among them, as an ionic conductive agent suitable in the present invention, for example, sodium perchlorate (MP-100, manufactured by Showa Chemical Industry Co., Ltd.), an acrylic monomer solution of lithium imide (Sanconol MTGA-50R, Sanko Chemical Industry ( And the like). These electrically conductive agents may be used individually by 1 type, and may use 2 or more types together. The compounding amount of the ionic conductive agent in the elastic layer forming composition depends on its type, but is the total of (A) urethane (meth) acrylate oligomer and (B) (meth) acrylate monomer constituting the UV curable resin. The range of 0.1 to 5.0 parts by mass, particularly 0.4 to 2.0 parts by mass, and further 0.4 to 1.2 parts by mass is preferable with respect to 100 parts by mass.

  In addition to the above, various known additives can be added to the elastic layer forming composition as long as the desired effects of the present invention are not impaired. In the present invention, the thickness of the elastic layer 2 is preferably 0.5 to 4 mm.

  Next, the surface layer 4 in the roller of the present invention can be formed of a surface layer forming composition containing a UV curable resin and a photopolymerization initiator and not containing a conductive agent. As the UV curable resin, the same resin as that used for the elastic layer can be used, and preferably a polybutadiene polyol or hydrogenated polybutadiene polyol, a polyisocyanate, and a (meth) acrylate having a hydroxyl group. And those containing a urethane (meth) acrylate oligomer obtained by reacting with. That is, as the (A) urethane (meth) acrylate oligomer, a UV curable resin using a urethane (meth) acrylate oligomer using a polybutadiene polyol or a hydrogenated polybutadiene polyol as a polyol is suitable. Thereby, in the surface layer 4, while being able to obtain a high resistance value, that is, a high insulating property, a high surface potential can be maintained. Therefore, it is possible to maintain the charging property of the toner in the developing roller and improve the printing quality, particularly the quality of fine line printing at the 1-dot level, without the occurrence of durable printing fog or the like.

  The polybutadiene polyol or hydrogenated polybutadiene polyol used for the surface layer 4 preferably has a weight average molecular weight of 1200 to 20000. If the weight average molecular weight is too small, the cured film tends to break and surface layer abrasion occurs. On the other hand, in order to increase the weight average molecular weight, the polyol / isocyanate ratio must be increased, and the compatibility between the hydrophobic polybutadiene polyol and the hydrophilic isocyanate deteriorates, increasing the number of unreacted components. End up. This causes toner sticking and adversely affects print quality. For this reason, those deviating from the aforementioned weight average molecular weight are not preferred.

  As a photoinitiator used for the surface layer 4, the thing similar to what was used for the said elastic layer 2 can be used, and it does not restrict | limit in particular. Further, the blending amount can be appropriately selected within the same range as in the case of the elastic layer 2. Furthermore, in addition to the above, various known additives can be added to the surface layer forming composition as long as the desired effects of the present invention are not impaired. In the present invention, the thickness of the surface layer 4 is preferably 1 to 20 μm.

  The shaft 1 used for the developing roller of the present invention is not particularly limited as long as it has good conductivity. A metal shaft, a resin shaft having a high rigidity disposed on the outer periphery of the metal shaft, a high rigidity Any of a resin base material, a metal hollow inside, or a cylindrical body made of high-rigidity resin may be used.

  Examples of the material for the metal shaft and the metal cylinder include iron, stainless steel, and aluminum. Examples of the high-rigidity resin include polyacetal, polyamide 6, polyamide 6 and 6, polyamide 12, polyamide 4 and 6, polyamide 6 and 10, polyamide 6 and 12, polyamide 11, polyamide MXD6, polybutylene terephthalate, polyphenylene oxide, Polyphenylene sulfide, polyethersulfone, polycarbonate, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone, polyethylene terephthalate, polyarylate, liquid crystal polymer, polytetrafluoroethylene, polypropylene, acrylonitrile-butadiene-styrene (ABS) resin , Polystyrene, polyethylene, melamine resin, phenol resin, silicone resin and the like. 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.

  In addition, when using highly rigid resin for the shaft 1, it is preferable to ensure sufficient electroconductivity by adding and disperse | distributing a electrically conductive agent in 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. Moreover, the compounding quantity of these electrically conductive agents is although it does not restrict | limit in particular, The range of 5-40 mass% is preferable with respect to the whole highly rigid resin composition, and the range of 5-20 mass% is more preferable.

  The outer diameter of the shaft 1 is preferably 5 to 20 mm, particularly 5 to 10 mm. In addition, when a resin material is used for the shaft 1, there is an advantage that an increase in the mass of the shaft 1 can be suppressed even if the outer diameter of the shaft 1 is increased.

In the developing roller of the present invention, the resistance value under conditions of a temperature of 10 ° C. and a humidity of 15% RH is 10 ⁴ to 10 ⁸ Ω, particularly 10 ⁵ to 10 ⁸ Ω, more preferably 10 ⁵ to 10 ⁷ Ω. It is preferable. Thereby, it is possible to improve the print image quality in a low temperature and low humidity environment.

  The developing roller of the present invention preferably comprises the elastic layer 2, the intermediate layer 3 and the surface layer 4 on the outer periphery of the shaft 1 using the elastic layer forming composition, the intermediate layer forming composition and the surface layer forming composition. Can be manufactured in sequence. Specifically, first, the elastic layer 2 is formed by applying the elastic layer forming composition to the outer periphery of the shaft 1 and then curing it by irradiating with UV light. Next, the intermediate layer 3 is formed by applying the intermediate layer forming composition to the outer periphery of the formed elastic layer 2 and then curing it by irradiating with UV light. Furthermore, after applying the surface layer forming composition to the outer periphery of the formed intermediate layer 3, the surface layer 4 is formed by irradiating and curing the UV light to obtain a suitable developing roller of the present invention. Can do. In the developing roller of the present invention, the elastic layer 2, in particular, the entire layer composed of the intermediate layer 3 and the surface layer 4 can be formed using a UV curable resin, so that a large amount of heat energy is required for production. The roller can be manufactured in a short time. In addition, since a curing furnace or the like is not required for forming each layer, a large amount of equipment costs are not required.

  In the present invention, examples of the method for applying the composition for forming each layer to the outer periphery of a shaft and the like include a spray method, a roll coater method, a dipping method, a die coating method, and the like. By using the die coating method, each layer can be applied quickly and reliably, and the working efficiency during roller production can be greatly improved.

  In the present invention, the UV light source used for curing each layer is not particularly limited, and examples thereof include a mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, and a xenon lamp. In particular, as a UV light source used for curing the intermediate layer, a non-powered UV lamp manufactured by Fusion UV Systems is suitable because it has a light emission wavelength of 254 nm center to 365 nm center and a strong light quantity. Among these, an H valve or a D valve can be preferably used. When a general mercury-filled UV lamp is used, the low-pressure mercury lamp has an emission wavelength of only up to about 254 nm, and is not suitable for curing the intermediate layer. Therefore, it is preferable to use a high-pressure mercury lamp having an emission wavelength up to about 365 nm for curing the intermediate layer. In addition, irradiation conditions such as irradiation intensity and integrated light amount upon UV light irradiation can be appropriately selected according to the components, composition, coating amount, and the like included in the composition for forming each layer, and are not particularly limited.

Hereinafter, the present invention will be described in more detail with reference to examples.
The elastic layer material shown in the following table was kneaded with a planetary mixer at 60 rpm for 1 hour to prepare an elastic layer forming composition. The obtained elastic layer forming composition was traverse-coated with a roll coater on the outer periphery of a shaft (outer diameter: 13 mm, material: aluminum). While rotating the coated shaft, the coated shaft was irradiated with UV light for 5 seconds using a non-powered UV lamp H bulb manufactured by Fusion UV Systems, and an elastic layer having a thickness of 1.5 mm was formed. Formed.

  Next, according to the intermediate | middle layer mixing | blending shown in following Table 3-10, it carried out similarly to the above, and prepared the composition for intermediate | middle layer formation. The obtained intermediate layer forming composition was traverse-coated with a roll coater on the outer periphery of the shaft on which the elastic layer was formed. While rotating the coated shaft, the coated shaft was irradiated with UV light for 5 seconds using a non-powered UV lamp H bulb manufactured by Fusion UV Systems to form an intermediate layer having a thickness of 3 μm. .

  Next, a composition for forming a surface layer was prepared in the same manner as described above in accordance with the surface layer composition shown in the following table. The obtained surface layer-forming composition was traverse-coated with a roll coater on the outer periphery of the shaft on which the elastic layer and the intermediate layer were formed. While rotating the coated shaft, the coated shaft was irradiated with UV light for 5 seconds using a non-powered UV lamp H bulb manufactured by Fusion UV Systems to form a surface layer having a thickness of 2 μm. The developing roller of each Example and Comparative Example was obtained.

<Resistance value under low temperature and low humidity (LL) and high temperature and high humidity (HH) environment>
For the developing rollers of the obtained Examples and Comparative Examples (Tables 3 to 5), the temperature was 10 ° C., the humidity was 15% RH (LL), the temperature was 32.5 ° C., and the humidity was 80% RH (HH). The resistance value was measured and the difference was calculated.

<Evaluation of Print Image Quality in Low Temperature and Low Humidity (LL) and High Temperature and High Humidity (HH) Environment>
About the developing roller of each Example and the comparative example (Tables 3-5) which were obtained, a commercially available printing machine (Brother Co., Ltd., HL-2240D) was temperature 10 degreeC, humidity 15% RH (LL), and temperature 32. Installed under conditions of 0.5 ° C and humidity 80% RH (HH), printed 1000 sheets of 1% density, then left overnight, printed 100% density black image, and measured transmission density Therefore, it was used as a standard for printing image quality. The result was x (density reduction) when the transmission density was 1.85 or less, Δ when the transmission density exceeded 1.85 and less than 1.90, and ◯ when the transmission density was 1.90 or more. X-Rite 310T manufactured by Sakata Inx Engineering Co., Ltd. was used for measurement of the transmission density.

  The above results are also shown in the following table.

＊１）ウレタンアクリレートオリゴマー：ＢＴ−０１Ｄ（第一工業製薬（株）製）
＊２）アクリルモノマーＡ：ＮＫエステルＡＭＯ（新中村化学工業（株）製）
＊３）アクリルモノマーＢ：ＮＫエステルＡ−ＳＡ（新中村化学工業（株）製）
＊４）アクリルモノマーＣ：ライトアクリレート１４ＥＧ−Ａ（共栄社化学（株）製）
＊５）アクリルモノマーＤ：カレンズＡＯＩ（昭和電工（株）製）
＊６）カーボンブラックＡ：ケッチェンブラック（三国色素（株）製（試作材料））
＊７）カーボンブラックＢ：デンカブラック（電気化学工業（株）製）
＊８）イオン導電剤Ａ：サンコノールＭＴＧＡ−５０Ｒ（リチウムイミドのアクリルモノマー溶液，三光化学工業（株）製）
＊９）イオン導電剤Ｂ：ＭＰ−１００（過塩素酸ナトリウム，昭和化学工業（株）製）
＊１０）ＩＲＧＡＣＵＲＥ１８４：（２５４ｎｍでの吸光係数３．３２×１０^４ｍｌ／ｇ・ｃｍ，ＢＡＳＦジャパン（株）製）
＊１１）ＩＲＧＡＣＵＲＥ８１９：（３６５ｎｍでの吸光係数２．３１×１０^３ｍｌ／ｇ・ｃｍ，ＢＡＳＦジャパン（株）製）

* 1) Urethane acrylate oligomer: BT-01D (Daiichi Kogyo Seiyaku Co., Ltd.)
* 2) Acrylic monomer A: NK ester AMO (manufactured by Shin-Nakamura Chemical Co., Ltd.)
* 3) Acrylic monomer B: NK ester A-SA (manufactured by Shin-Nakamura Chemical Co., Ltd.)
* 4) Acrylic monomer C: Light acrylate 14EG-A (manufactured by Kyoeisha Chemical Co., Ltd.)
* 5) Acrylic monomer D: Karenz AOI (manufactured by Showa Denko KK)
* 6) Carbon Black A: Ketjen Black (manufactured by Mikuni Dye Co., Ltd. (prototype material))
* 7) Carbon Black B: Denka Black (manufactured by Denki Kagaku Kogyo Co., Ltd.)
* 8) Ionic conductive agent A: Sanconol MTGA-50R (acrylic monomer solution of lithium imide, manufactured by Sanko Chemical Industries, Ltd.)
* 9) Ionic conductive agent B: MP-100 (sodium perchlorate, manufactured by Showa Chemical Industry Co., Ltd.)
* 10) IRGACURE 184: (absorption coefficient at 254 nm 3.32 × 10 ⁴ ml / g · cm, manufactured by BASF Japan Ltd.)
* 11) IRGACURE 819: (absorption coefficient at 365 nm 2.31 × 10 ³ ml / g · cm, manufactured by BASF Japan Ltd.)

<Evaluation of cured film>
About the developing roller of each obtained Example and the comparative example (Tables 6-10), the hardening state of the film | membrane was evaluated by direct contact. As a result, it was judged that the case where it did not change even when touched with a finger was good, and the case where it peeled off when touched was judged as bad. In addition, the number of squares remaining without being peeled off is obtained by making a 2 mm square 5 × 5 incision on the surface of each developing roller, affixing 10 times with a cloth adhesive tape (Sekisui-Crosslight tape), and peeling off. X was evaluated as X / 25. The results are also shown in the table below.

＊１２）ＩＲＧＡＣＵＲＥ１２７：（２５４ｎｍでの吸光係数７．３４×１０^４ｍｌ／ｇ・ｃｍ，ＢＡＳＦジャパン（株）製）
＊１３）ＩＲＧＡＣＵＲＥ２９５９：（２５４ｎｍでの吸光係数３．０３×１０^４ｍｌ／ｇ・ｃｍ，ＢＡＳＦジャパン（株）製）
＊１４）ＩＲＧＡＣＵＲＥ３６９：（３６５ｎｍでの吸光係数７．８６×１０^３ｍｌ／ｇ・ｃｍ，ＢＡＳＦジャパン（株）製）
＊１５）ＩＲＧＡＣＵＲＥ９０７：（３６５ｎｍでの吸光係数４．６７×１０^２ｍｌ／ｇ・ｃｍ，ＢＡＳＦジャパン（株）製）

* 12) IRGACURE127: (Absorption coefficient at 254 nm 7.34 × 10 ⁴ ml / g · cm, manufactured by BASF Japan Ltd.)
* 13) IRGACURE 2959: (absorption coefficient at 254 nm 3.03 × 10 ⁴ ml / g · cm, manufactured by BASF Japan Ltd.)
* 14) IRGACURE 369: (absorption coefficient at 365 nm 7.86 × 10 ³ ml / g · cm, manufactured by BASF Japan Ltd.)
* 15) IRGACURE907: (Absorption coefficient at 365 nm 4.67 × 10 ² ml / g · cm, manufactured by BASF Japan Ltd.)

  As shown in the above table, in the developing roller of the example in which the intermediate layer is blended with a predetermined amount or more of carbon black together with the UV curable resin, and further, two specific photopolymerization initiators are blended, the resistance There was little environmental fluctuation of values, and good print quality was obtained under both low temperature and low humidity and high temperature and high humidity conditions. Moreover, in the developing roller of this Example, it was confirmed that the problem of peeling of the coating film due to poor curing of the intermediate layer did not occur.

DESCRIPTION OF SYMBOLS 1 Shaft 2 Elastic layer 3 Intermediate | middle layer 4 Surface layer 10 Developing roller 11 Toner supply roller 12 Photosensitive drum 13 Toner 14 Layering blade 15 Transfer part 16 Cleaning part 17 Cleaning blade

Claims (3)

In the developing roller comprising an elastic layer, an intermediate layer and a surface layer in order on the outer periphery of the shaft,
The intermediate layer contains 1 part by mass or more of carbon black with respect to 100 parts by mass of the ultraviolet curable resin, and further has a photopolymerization initiator having an extinction coefficient at 254 nm of 2 × 10 ⁴ ml / g · cm or more. Containing 5 to ² parts by mass and 0.5 to 2 parts by mass of a photopolymerization initiator having an extinction coefficient at 365 nm of 4 × 10 ² ml / g · cm or more ,
The composition used for forming the surface layer contains a urethane (meth) acrylate oligomer obtained by reacting a polybutadiene polyol or hydrogenated polybutadiene polyol, a polyisocyanate, and a (meth) acrylate having a hydroxyl group. Development roller.   The developing roller according to claim 1, wherein the elastic layer contains an ultraviolet curable resin and an ionic conductive agent. 3. The developing roller according to claim 1, wherein a resistance value is 10 ⁴ to 10 ⁸ Ω under conditions of a temperature of 10 ° C. and a humidity of 15% RH.

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