JP2009008894A - Developing roll for electrophotographic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roll for electrophotographic equipment, including a surface layer excellent in toner adhesion resistance and wear resistance. <P>SOLUTION: The developing roll for electrophotographic equipment includes a surface layer composed of a hardened product of an ultraviolet cure conductive composition containing (A) a (meth)acrylate monomer having an ethylene oxide unit introduced to the molecular structure and (B) a urethane (meth)acrylate. The ratio of the component (A)/the component (B) (by mass) is preferably in the range of 5/95-95/5. The number of (meth)acryloyl groups contained in one urethane (meth)acrylate is preferably in the range of 1 to 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing roll for electrophotographic equipment.

  In recent years, electrophotographic apparatuses such as copying machines, printers, and facsimiles that employ an electrophotographic system have been widely used. As a developing method in this type of electrophotographic apparatus, a contact developing method is known.

  In the contact development method, a toner layer is formed on the surface of the developing roll by pressing the toner layer forming blade against the surface of the developing roll. A toner image is formed on the surface of the photosensitive drum by bringing the roll surface into contact with the surface of the photosensitive drum.

  As a conventional developing roll, for example, Patent Document 1 discloses a developing roll in which a surface layer is formed by applying, drying, and thermosetting a urethane-based coating on the outer periphery of a conductive silicone rubber layer formed on the outer periphery of a core metal. It is disclosed.

  Specifically, the urethane-based paint is a paint in which isocyanate is mixed with a urethane polyol prepolymer, diluted with a solvent, and carbon black (electronic conductive agent) and urethane particles (surface roughness forming particles) are added. Is used.

  In recent years, due to demands for low VOC and energy saving, the surface layer has been formed with ultraviolet curable resin or the like without suppressing the solvent as much as possible and without removing the solvent by heat treatment.

  For example, Patent Document 2 describes a developing roll in which a surface layer is formed by curing an ultraviolet curable conductive composition on the outer periphery of a conductive silicone rubber layer formed on the outer periphery of a core metal.

  Specifically, a composition containing 50 parts by weight of polyethylene glycol diacrylate, 50 parts by weight of methoxypolyethylene glycol acrylate, 3 parts by weight of an ionic conductive agent, and 1 part by weight of a photoinitiator is used as the above composition. ing.

JP 2006-133257 A JP 2006-274242 A

  In recent years, in the field of electrophotographic equipment, demands for speeding up, high image quality, long life, etc. of electrophotographic equipment are rapidly increasing. In order to cope with higher speed and higher image quality, toners are progressing toward lower melting points and smaller diameters. Therefore, a function that can cope with the above-described tendency is also required on the developing roll side. However, conventionally known developing rolls have room for improvement in the following points.

  That is, when the toner has a low melting point, when the toner layer is formed on the surface of the developing roll, the toner is easily dissolved by heat generated by friction between the toner layer forming blade and the surface of the developing roll. For this reason, the toner adheres to the surface of the developing roll (filming), which reduces the chargeability and makes it difficult to extend the life.

  Further, when the diameter of the toner is reduced, toner charging efficiency due to friction decreases. Therefore, if the linear pressure of the blade for forming the toner layer is increased for the purpose of preventing this, the frictional heat increases and the toner adhesion is more likely to occur. Therefore, the above problem becomes more remarkable.

  In addition to these, the developing roll containing an electronic conductive agent such as carbon black in the surface layer is electronically conductive, and therefore has a large roll resistance variation and a low charge decay rate (slow charge decay rate). Responsiveness is also low.

  Further, when carbon black, a filler, or the like is contained in the surface layer, fine unevenness caused by carbon black or the like existing on the surface of the surface layer is likely to become a starting point of toner adhesion.

  Further, when the roughness forming particles are included in the surface layer, the roughness forming particles are worn by friction, and the durability is lowered. In order to avoid this, it is also conceivable to add roughness-forming particles to the lower layer of the surface layer to give the surface layer an uneven shape.

  However, in the case of a surface layer material containing a relatively large amount of a solvent, such as a conventional urethane-based paint, the convex portion of the lower layer (corresponding to the top position of the roughness-forming particles) in the coating and drying process when forming the surface layer The thickness of the surface layer formed on the top is reduced. Therefore, the surface layer on the upper part of the roughness forming particles wears in a short period of time, and it is still difficult to improve the durability.

  On the other hand, a developing roll in which a surface layer is formed by ultraviolet curing the above-described ultraviolet curable conductive composition has a relatively high tackiness of the surface layer. For this reason, the toner tends to adhere to the surface of the developing roll in the first place, and there is a problem that the toner adhesion resistance is inferior in combination with the problem of the toner having a low melting point and a small diameter.

  The present invention has been made in view of the above circumstances, and a problem to be solved by the present invention is to provide a developing roll for an electrophotographic apparatus having excellent toner adhesion resistance and abrasion resistance on the surface layer.

  In order to solve the above-described problems, the developing roll for electrophotographic equipment according to the present invention has (A) a (meth) acrylate monomer in which an ethylene oxide unit is introduced in the molecular structure, and (B) urethane (meth). The gist is that it comprises a cured product of an ultraviolet curable conductive composition containing acrylate.

  Here, the component (A) / component (B) (mass ratio) is preferably in the range of 5/95 to 95/5.

  The number of (meth) acryloyl groups contained in one molecule of the (B) urethane (meth) acrylate is preferably in the range of 1 to 6.

  Moreover, the said ultraviolet curable conductive composition is good to contain the (C) ionic conductive agent.

  Further, the roll configuration of the developing roll includes a shaft body, a base layer formed on the outer periphery of the shaft body, an intermediate layer formed on the outer periphery of the base layer, and a surface layer formed on the outer periphery of the intermediate layer. A configuration having the same is preferable.

  At this time, the intermediate layer preferably contains roughness forming particles.

  The surface layer of the developing roll for electrophotographic equipment according to the present invention comprises a cured product of an ultraviolet curable conductive composition containing a specific component (A) and a component (B).

  That is, by using the component (B) in addition to the component (A), the hardness of the cured product is relatively increased, the friction coefficient is decreased, and tackiness (adhesiveness) resulting from the component (A) is reduced. Decreases. Therefore, the toner adhesion resistance is improved, filming hardly occurs, and the durability is excellent.

  In addition, the wear resistance of the surface layer is improved. Moreover, since it is easy to homogenize from the surface of the surface layer to the inside, performance deterioration with time due to wear hardly occurs.

  Further, since the surface layer made of the cured product is ionic conductive, the roll resistance variation is small, the charge decay rate is high, and the electrical response is high.

  Moreover, the said ultraviolet curable conductive composition hardens | cures rapidly by ultraviolet irradiation after application | coating. Therefore, the surface layer thickness hardly changes due to the uneven shape of the lower layer, and there is an advantage that it can contribute to the improvement of the durability.

  Here, when the component (A) / component (B) (mass ratio) is within a specific range, the surface layer is excellent in the balance of toner adhesion resistance and abrasion resistance.

  Moreover, when the number of (meth) acryloyl groups contained in one molecule of the urethane (meth) acrylate of the component (B) is in the range of 1 to 6, the surface layer becomes too hard after the composition is cured. Therefore, the stress on the toner can be reduced.

  Moreover, when the ultraviolet curable conductive composition contains (C) an ion conductive agent, it becomes easy to adjust the electric resistance of the cured product.

  In addition, when the roll has an intermediate layer between the base layer and the surface layer, and the intermediate layer contains the particles for forming the roughness, the composition is quickly applied by ultraviolet irradiation after coating. Harden. Therefore, a concavo-convex shape can be imparted to the surface layer surface along the concavo-convex shape formed in the intermediate layer. Therefore, it can contribute to the improvement of durability.

  Hereinafter, the developing roll for electrophotographic apparatus according to this embodiment (hereinafter, also referred to as “main developing roll”) will be described.

  FIG. 1 is a circumferential cross-sectional view illustrating an example of the developing roll. For example, as shown in FIG. 1, the developing roll 10 has a laminated structure in which a base layer 14, an intermediate layer 16, and a surface layer 18 are laminated in this order on the outer periphery of the shaft body 12.

  FIG. 2 is a circumferential sectional view showing another example of the developing roll. The present developing roll 10 is not limited to the embodiment shown in FIG. 1, and as shown in FIG. 2, a surface layer 18 may be directly laminated on the outer periphery of the base layer 14.

  Each of the base layer, the intermediate layer, and the surface layer may be composed of a single layer or a plurality of layers. Preferably, the base layer, the intermediate layer, and the surface layer are preferably composed of a single layer from the viewpoint of simplifying the laminated structure and improving the roll productivity.

  Any shaft body may be used as long as it has conductivity. Specific examples include solid bodies made of metal such as iron, stainless steel, and aluminum, and a cored bar made of a hollow body. Moreover, you may apply | coat an adhesive agent, a primer, etc. to the surface of a shaft body as needed. The adhesive, primer, etc. may be made conductive as necessary.

  The base layer may be in any form of non-foam (solid) or foam (sponge). As the main material for forming the base layer, a rubber elastic material can be suitably used. Specific examples of the rubber elastic material include silicone rubber, ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (H-NBR), and styrene-butadiene rubber ( SBR), butadiene rubber (BR), isoprene rubber (IR), acrylic rubber (ACM), chloroprene rubber (CR), urethane rubber, fluorine rubber, hydrin rubber (ECO, CO), urethane elastomer, natural rubber (NR), etc. Can be illustrated. These may be used alone or in combination.

  As the rubber elastic material, silicone rubber, butadiene rubber, hydrin rubber, urethane elastomer and the like are preferable from the viewpoints of low hardness and less sag.

The base layer, for imparting conductivity, carbon black, _{graphite, c-TiO 2, c-} ZnO, c-SnO 2 (c- means conductive.), Ion conductive agent (quaternary ammonium salt, Conventionally known conductive agents such as borates and surfactants can be appropriately added to the above materials. Furthermore, if necessary, a foaming agent, a crosslinking agent, a crosslinking accelerator, a softening agent (oil) and the like may be appropriately added.

  In order to form the base layer on the outer periphery of the shaft body, the shaft body is coaxially installed in the hollow portion of the roll molding die, injected with the composition for forming the base layer, and heated and cured. Demolding (casting method), extruding the base layer forming composition on the surface of the shaft (extrusion method), etc. In addition, when a plurality of base layers are formed, an operation according to the above method may be repeated.

  Although the thickness of a base layer is not specifically limited, Preferably, it can select from the range of 0.1-10 mm, More preferably, it is 1-5 mm.

The volume resistivity of the base layer is preferably in the range of 10 ² to 10 ¹⁰ Ω · cm, more preferably 10 ³ to 10 ⁹ Ω · cm, and even more preferably in the range of 10 ⁴ to 10 ⁸ Ω · cm. You can choose from.

  The developing roll may have an intermediate layer between the base layer and the surface layer.

  Specific examples of the main material for forming the intermediate layer include, for example, silicone resins, fluorine resins, polymethyl methacrylate (PMMA), polycarbonate, polyamide resins, urethane resins, (meth) acrylic resins, and melamine. Resins such as resins, epoxy resins, urethane elastomers, nitrile rubber (NBR), hydrogenated nitrile rubber (hydrogenated NBR), epichlorohydrin rubber, etc., modified products obtained by modifying these resins and rubber with silicone, fluorine, etc. Etc. can be illustrated. These may be used alone or in combination.

  The main material for forming the intermediate layer is preferably a urethane-based resin, a urethane-based elastomer, a (meth) acrylic resin, or the like from the viewpoints of little settling and easy dispersion of particles.

The intermediate layer, for imparting conductivity, carbon black, graphite, iron _{oxide, c-TiO 2, c-} ZnO, c-SnO 2 (c- means conductive.), Ion conductive agent (quaternary Conventionally known conductive agents such as ammonium salts, borates, surfactants, etc.) can be appropriately added to the above materials. Furthermore, you may add a crosslinking agent, a crosslinking accelerator, a hardening | curing agent, etc. suitably as needed.

  The developing roll preferably has an appropriate concavo-convex shape on the roll surface in order to ensure good toner transportability. As a method of imparting unevenness to the roll surface, there is a method of adding roughness forming particles to the surface layer, but from the viewpoint of wear resistance, long life, etc., the intermediate layer contains roughness forming particles. Is preferred.

  In this case, as shown in FIG. 3, the uneven shape formed by the roughness forming particles 20 contained in the intermediate layer 16 forms an uneven shape on the roll surface, that is, the surface of the surface layer 18. . From the viewpoint of uniform surface roughness, the roughness forming particles 20 are not substantially stacked in the thickness direction of the intermediate layer 16, that is, the roughness forming particles are present on substantially the same plane. It is preferable.

  Specific examples of the roughness forming particles include urethane particles, crosslinked polymethyl methacrylate particles, acrylic particles, urea resin particles, amide particles and other resin particles, rubber particles, silica particles, and the like. it can. These may be contained alone or in combination of two or more.

  In order to form an intermediate layer on the outer periphery of the base layer, a monomer / oligomer that can be a polymer that mainly constitutes the intermediate layer, or the polymer itself that mainly constitutes the intermediate layer, a conductive agent, and roughness forming particles. Are mixed with a suitable solvent such as methyl ethyl ketone to prepare a composition for forming an intermediate layer having a viscosity suitable for coating.

  Then, using various coating methods such as a roll coating method, a dipping method, and a spray coating method, the intermediate layer forming composition is applied to the outer periphery of the base layer, dried, and subjected to heat treatment as necessary. An intermediate layer can be formed. Note that when a plurality of intermediate layers are formed, an operation according to the above method may be repeated.

  Although the thickness of an intermediate | middle layer is not specifically limited, Preferably, it can select from the range of 1-100 micrometers, More preferably, it is 3-50 micrometers.

  The average particle diameter of the roughness forming particles can be appropriately selected according to the thickness of the intermediate layer and the like, and is not particularly limited. Preferably, it can be selected from the range of 1 to 50 μm, more preferably 5 to 30 μm.

Moreover, the volume resistivity of the intermediate layer is preferably selected from the range of 10 ² to 10 ¹⁰ Ω · cm, more preferably from 10 ⁴ to 10 ⁷ Ω · cm.

  In this developing roll, the surface layer is formed from a cured product of an uncured ultraviolet curable conductive composition (hereinafter, also simply referred to as “conductive composition”) containing a specific component.

  Here, the said electrically conductive composition contains (A) (meth) acrylate monomer and (B) urethane (meth) acrylate as a specific component.

  The (A) (meth) acrylate monomer has an ethylene oxide unit introduced in the molecular structure. This ethylene oxide unit contributes to an improvement in compatibility with an ionic conductive agent that may be contained in the conductive composition.

  The content of the ethylene oxide unit introduced into the molecular structure is preferably in the range of 1 to 98% by mass, more preferably 20 to 98, from the viewpoint of easily reducing the electric resistance of the cured product. It is good that it exists in the range of 40 mass%, More preferably in the range of 40-98 mass%.

  In addition, content of an ethylene oxide unit can be measured using NMR (nuclear magnetic resonance apparatus) etc., for example.

  (A) The monofunctional (meth) acrylate monomer may have one or more other units introduced into the molecular structure in addition to the ethylene oxide unit.

  Examples of the other units include alkylene oxide units having 3 to 20 carbon atoms, trimethylolpropane units, pentaerythritol units, ethylhexyl carbitol units, glycerin units, nonylphenol units, paracumylphenol units, bisphenol A units, Examples include units containing cyclic unsaturated structures such as styrene oxide units, isocyanuric acid units, bisphenol F units, phthalic acid units, and phenoxy units. These may be contained alone or in combination of two or more.

  The (A) (meth) acrylate monomer may be monofunctional or polyfunctional. Alternatively, a monofunctional (meth) acrylate monomer and a polyfunctional (meth) acrylate monomer may be mixed. Preferably, the (A) (meth) acrylate monomer is monofunctional from the viewpoint of easily reducing the roll resistance.

  In addition, “(meth) acrylate monomer is monofunctional” means that one (meth) acrylate monomer has one (meth) acryloyl group. Moreover, “(meth) acrylate monomer is polyfunctional” means that one molecule of (meth) acrylate monomer has two or more (meth) acryloyl groups.

  Specific examples of the (A) (meth) acrylate monomer include, for example, methoxypolyethylene glycol (meth) acrylate, methoxypolyethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, polyethylene glycol di (meth) acrylate, Phenoxyethylene oxide modified acrylate (Chemical formula 1 in Table 1), Nonylphenol ethylene oxide modified acrylate (Chemical formula 2 in Table 1), methoxyethylene oxide modified acrylate (Chemical formula 3 in Table 1), ethoxyethylene oxide modified acrylate (Chemical formula 4 in Table 1) ) 2-ethylhexyl ethylene oxide modified acrylate (Chemical formula 5 in Table 1), butoxyethylene oxide modified acrylate (Chemical formula 6 in Table 1), ethylene oxide modified cresol accelerator (Table 1 of 7, etc.) and the like can be exemplified. These may be contained alone or in combination of two or more.

  On the other hand, (B) urethane (meth) acrylate is a compound having both a urethane bond and a (meth) acryloyl group. Specific examples of the (B) urethane (meth) acrylate include, for example, a type in which a hydroxyl group-containing acrylate is directly added to an isocyanate compound, a type in which a hydroxyl group-containing acrylate is directly added to a polyisocyanate compound such as isocyanurate, and a polyol. A urethane (meth) acrylate such as a type in which a hydroxyl group-containing acrylate is added to a reaction product of an isocyanate compound can be exemplified. These may be contained alone or in combination of two or more.

  Examples of the isocyanate compound include pure MDI, crude MDI, and IPDI. Examples of the polyol include ester-based and ether-based polyols. Examples of the hydroxyl group-containing acrylate include hydroxyethyl acrylate, hydroxypropyl acrylate, and pentaerythritol triacrylate.

  Among these, urethane (meth) acrylates of a type in which a hydroxyl group-containing acrylate is added to a reaction product of a polyol and an isocyanate compound can be suitably used from the viewpoint of flexibility and strength.

  Further, (B) the number of (meth) acryloyl groups contained in one molecule of urethane (meth) acrylate is such that the surface layer does not become too hard after the composition is cured, and the toner resistance can be reduced. From the viewpoint of facilitating the balance between adhesion and wear resistance, it is preferably in the range of 1 to 6, more preferably in the range of 2 to 6, and even more preferably 3 It is good to be within the range of 6 to 6.

  The conductive composition is preferably (A) component / (B) component (mass ratio) from the viewpoint of improving the balance of toner adhesion resistance and abrasion resistance of the surface layer after curing. 5/95 to 95/5, more preferably 10/90 to 90/10, and even more preferably 30/70 to 70/30.

  The conductive composition may contain other photopolymerization components as necessary in addition to the components (A) and (B).

  In addition, as another photopolymerization component, the monofunctional or polyfunctional (meth) acrylate monomer etc. in which the ethylene oxide unit is not introduce | transduced in molecular structure can be illustrated, for example.

  Specific examples of other photopolymerization components include hexadiol diacrylate, nonanediol diacrylate, propylene glycol diacrylate, isocyanuric acid triacrylate, trimethylolpropane triacrylate, hydroxyphenyl monoacrylate, and ditrimethylolpropane tetraacrylate. Examples include acrylate and hydroxyethyl monoacrylate. You may use these 1 type or in mixture of 2 or more types.

  Further, the conductive composition is cured by photopolymerization with light such as ultraviolet rays, and contains a photopolymerization initiator.

  The photopolymerization initiator is not particularly limited, and any photopolymerization initiator can be used as long as it can be normally used.

  Specific examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, 2-methylbenzoin, benzyl, benzyldimethylketal, diphenyl sulfide, and tetramethylthiuram monosulfide. , Diacetyl, eosin, thionine, mihira-ketone, anthracene, anthraquinone, acetophenone, α-hydroxyisobutylphenone, p-isopropyl αhydroxyisobutylphenone, α · α 'dichloro-4-phenoxyacetophenone, 1-hydroxy-1-cyclohexylacetophenone 2,2-dimethoxy-2-phenylacetophenone, methylbenzoyl formate, 2-methyl-1- [4- (methylthio) phenyl] .2.morpholino-propene, thioxanthone , Benzophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 1-hydroxy-cyclohexyl-phenyl-ketone, benzophenone, 2-methyl-1- [4 -(Methylthio) phenyl] -2-monforinopropanone 1,2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone 1,2-hydroxy-2-methyl-1-phenyl- Propan-1-one, 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, Bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyryl) titanium), -Hydroxy-2-methyl-1-phenylpropan-1-one, bisacylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, (η5-2,4-cyclopentadien-1-yl ) [(1,2,3,4,5,6-η)-(1-methylethyl) benzene] -iron (1 +)-hexafluorophosphate (1-) and the like. These can be used alone or in combination of two or more.

  The lower limit of the content of the photopolymerization initiator is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, with respect to 100 parts by mass of the polymerization component contained in the conductive composition. Even more preferably, it is 1 mass part or more.

  On the other hand, the upper limit of the content of the photopolymerization initiator is preferably 50 parts by mass or less, more preferably 10 parts by mass or less with respect to 100 parts by mass of the polymerization component contained in the conductive composition. good.

  The conductive composition preferably further contains (C) an ion conductive agent as a preferred additive component. (C) When an ionic conductive agent is included, it is easy to adjust the electrical resistance of the surface layer, which is a cured product of the conductive composition.

  The ionic conductive agent is not particularly limited, and any ionic conductive agent can be used as long as it can be used in the field of electrophotographic equipment.

Specific examples of the ionic conductive agent include, for example, quaternary ammonium perchlorate represented by Chemical Formula 8 (in the chemical formula 8, R ₁ , R ₂ , R ₃ , and R ₄ have 1 carbon atom) A borate represented by Chemical formula 9 (which represents a methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, decyl group, phenyl group, xylyl group, etc.) In formula 9, R ₁ , R ₂ , R ₃ , R ₄ are alkyl groups having 1 to 18 carbon atoms, such as methyl group, ethyl group, propyl group, butyl group, hexyl group, phenyl group, xylyl group, etc. M ^{n +} is an alkali metal ion or alkaline earth metal ion, and represents lithium ion, sodium ion, potassium ion, calcium ion, etc.). These may be used alone or in combination.

(Chemical formula 8)

(Chemical 9)

  The lower limit value of the content of the ionic conductive agent is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, more preferably 100 parts by mass of the polymerization component contained in the conductive composition. More preferably, it is 1 mass part or more.

  On the other hand, the upper limit value of the content of the ionic conductive agent is preferably 50 parts by mass or less, more preferably 10 parts by mass or less, with respect to 100 parts by mass of the polymerization component contained in the conductive composition. .

  In addition to the above, the conductive composition may include a light stabilizer, a viscosity modifier, an anti-aging agent, a processing aid, a lubricant, a flame retardant, a plasticizer, a foaming agent, a filler, a crosslinking agent, and a crosslinking aid. 1 type, or 2 or more types of various additives, such as an agent, a dispersing agent, an antifoamer, a pigment, a mold release agent, and the particle for roughness formation, may be contained.

  The conductive composition described above has a viscosity (25 ° C.) of preferably 100,000 mPa · s or less, more preferably 10,000 mPa · s or less, from the viewpoint of good handleability. From the standpoint of excellent coating properties and the like, it is even more preferably 5000 mPa · s or less.

  From the viewpoint of adjusting the viscosity within the above range, the conductive composition is made of an organic solvent such as methyl ethyl ketone, toluene, acetone, ethyl acetate, butyl acetate, methyl isobutyl ketone (MIDK), THF, DMF, methanol, ethanol, etc. A solvent such as a water-soluble solvent may be appropriately contained. Further, it may be solventless.

  The conductive composition described above can be prepared by weighing various materials so as to have a desired composition and mixing them by a mixing means such as a stirrer or a sand mill. In addition, you may perform a defoaming process etc. after mixing during mixing.

  As a method for forming a surface layer on the outer periphery of the base layer or the intermediate layer using such a conductive composition, for example, various coating methods such as a roll coating method, a dipping method, and a spray coating method can be applied. .

  More specifically, for example, the conductive composition is applied on the surface of a roll body in which a base layer and an intermediate layer are arbitrarily formed on a shaft body by a roll coating method, and cured by irradiating ultraviolet rays. Examples of such a method include a method of immersing the roll body in a storage tank in which the conductive composition is stored, and a method of curing the roll body by irradiating it with ultraviolet rays. In the case of containing a solvent, in the case of containing a monomer component, heat treatment may be performed after ultraviolet curing.

  These coating methods may be used alone or in combination. The coating method may be repeated once or twice or more.

  The thickness of the surface layer is not particularly limited, but it is preferably 0.01 to 100 μm, more preferably 1 to 50 μm, and still more preferably, from the viewpoint that it is difficult to increase the electrical resistance and wear. It is good to select from the range of 3-30 micrometers.

The volume resistivity of the surface layer is preferably 1 × 10 ⁶ to 1 × 10 ¹³ Ω · cm, more preferably 1 × 10 ⁸ to 1 × 10 ¹¹ , from the viewpoint of ensuring withstand voltage and adjusting the roll resistance. It can be selected from the range of Ω · cm.

  Hereinafter, the present invention will be described in detail using examples.

1. Preparation of conductive composition used for surface layer of developing roll according to examples and comparative examples Weigh various materials so as to have a blending ratio (unit is part by mass) shown in Table 2 to be described later, and stir these with a stirrer. After mixing, each conductive composition used for the surface layer of the developing roll according to Examples 1 to 6 was prepared by leaving it at room temperature for 24 hours (for defoaming).

Under the present circumstances, the various materials used at the time of preparation of each said electrically conductive composition are as follows.
Polyethylene glycol diacrylate (CH ₂ ═CHCOO (C ₂ H ₄ O) _n —COCH═CH ₂ , n≈23) [Shin Nakamura Chemical Co., Ltd., “NK Ester A-1000”]

-Urethane acrylate (1) (functional group number f = 2) [manufactured by Toagosei Co., Ltd., "Aronix M1600"]
-Urethane acrylate (2) (functional group number f = 4) [manufactured by Daicel UCB, "Ebecryl 8210"]
-Urethane acrylate (3) (functional group number f = 6) [Daicel UCB Co., Ltd., "Ebecryl 1290"]

Photoinitiator [Ciba Specialty Chemicals Co., Ltd., “Irgacure 127”]

・ Ionic conductive agent (trimethyloctadecyl ammonium perchlorate)

  Moreover, the acrylic silicone resin-type coating material prepared as follows was used for the electroconductive composition used for the surface layer of the image development roll which concerns on the comparative example 1. FIG.

  333 parts by mass of an acrylic silicone resin (manufactured by Toagosei Co., Ltd., “Symac US270”) is dissolved in 167 parts by mass of a solvent (methyl ethyl ketone), and carbon black ([Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.] is added to the solution. ]) 30 parts by mass was mixed, and dispersed by circulating for 1 hour in a bead mill to prepare an acrylic silicone resin-based paint.

  Moreover, the hydrin rubber-type coating material prepared as follows was used for the electroconductive composition used for the surface layer of the image development roll concerning the comparative example 2. FIG.

  Hydrine rubber (Daiso Co., Ltd., “Epichromer CG102”) 100 parts by mass, stearic acid (Kao Co., Ltd., “Lunac S-30”) 1 part by mass, zinc oxide 2 types (Mitsui Metal Industries ( 5 parts by mass), 3 parts by mass of acid acceptor (manufactured by Kyowa Chemical Industry Co., Ltd., “DHT-4A”), 1.5 parts by mass of powder sulfur (manufactured by Tsurumi Chemical Co., Ltd.), 1.5 parts by mass of thiazole vulcanization accelerator (Ouchi Shinsei Chemical Co., Ltd., “Noxeller DM”) and thiuram vulcanization accelerator (Ouchi Shinsei Chemical Co., Ltd., “Noxeller TS”) ) 0.5 parts by mass, 30 parts by mass of activated calcium carbonate (manufactured by Shiraishi Kogyo Co., Ltd., “Shiroka Hana CC”), 0.5 parts by mass of ammonium perchlorate, and MEK / toluene = 1/1 mixed solution 1287 Mix the mass part with mixing means such as a stirrer. It was prepared hydrin-based paint by.

2. Characteristic Evaluation of Cured Product of Conductive Composition Next, property evaluation of the cured product of each obtained conductive composition was performed as follows.

(Coefficient of friction)
Each conductive composition according to Examples 1 to 6 was coated on a glass plate by a bar coating method, and then irradiated with ultraviolet rays to prepare each sheet-like cured product having a thickness of about 100 μm, a length of 100 mm, and a width of 100 mm. . At this time, the distance between the UV lamp (mercury lamp type) of the UV irradiator (“IB031-2A / BM” manufactured by Igraphic Co., Ltd.) and each of the coated compositions was 200 mm, and the UV light was irradiated for 50 seconds (UV intensity 100 mW / cm ² ).

  On the other hand, each coating material according to Comparative Examples 1 and 2 was coated on a glass plate by a bar coating method, and then heat-treated (Comparative Example 1 was 100 ° C. for 30 minutes, Comparative Example 2 was 160 ° C. for 30 minutes) Each sheet-like cured product having a thickness of about 100 μm, a length of 100 mm, and a width of 100 mm was produced.

  Next, using a friction coefficient measuring machine (“DFPM-S” manufactured by Kyowa Interface Science Co., Ltd.), the friction coefficient μs of each sheet-like cured product produced was measured under the measurement conditions of the tip: a hard sphere and a measurement load: 50 g. It was measured.

(Electric resistance)
A 1 cm square silver paste electrode was formed on the surface of each sheet-like cured product, and volume resistivity when 100 V was applied was measured according to JIS K6271 (double ring electrode method).

3. Production of developing roll for electrophotographic equipment (Preparation of composition for forming base layer)
100 parts by mass of conductive millable silicone rubber (manufactured by Toshiba Silicone Co., Ltd., “XE23-A4902”) and 1.5 parts by mass of peroxide-based crosslinking agent (manufactured by Toshiba Silicone Co., Ltd., “TC-8”) The composition for base layer formation was prepared by kneading with a kneader.

(Preparation of intermediate layer forming composition)
100 parts by mass of polyurethane-based elastomer (Sakai Chemical Co., Ltd., “UN278”), 30 parts by mass of carbon black (“Denka Black” manufactured by Denki Kagaku Kogyo Co., Ltd.), 10 parts by mass of isocyanate, urethane By dispersing, mixing and stirring 20 parts by mass of particles (Dainippon Ink & Chemicals, “Bernock CFB100”, average particle size 20 μm) and 400 parts by mass of methyl ethyl ketone, the composition for forming an intermediate layer is obtained. Prepared.

(Formation of base layer)
The base layer-forming composition was poured into a cylindrical mold in which a core metal (diameter 6 mm) was set coaxially, heated at 150 ° C. for 45 minutes, cooled and demolded. This produced each roll body provided with the base layer (thickness 3 mm) which consists of a silicone rubber type composition in the outer periphery of a metal core.

(Formation of intermediate layer)
An intermediate layer (thickness: 10 μm) was formed on the outer periphery of the base layer by coating the surface of each roll body with the composition for forming an intermediate layer using a roll coating method, followed by heat crosslinking at 180 ° C. for 30 minutes.

(Formation of surface layer)
Similarly, the conductive composition according to Examples 1 to 6 and the conductive composition according to Comparative Examples 1 and 2 are formed on the surface of the intermediate layer of each roll body on which the intermediate layer is formed using a roll coating method. Each was coated.

Then, about Examples 1-6, each conductive composition was ultraviolet-cured by irradiating an ultraviolet-ray (UV intensity 100mW / cm < ² >, 50 second irradiation), and each surface layer (thickness 5 micrometers) on the outer periphery of each intermediate | middle layer. ) Was formed. This produced the developing roll (3 layer structure) which concerns on Examples 1-6.

  On the other hand, for Comparative Examples 1 and 2, each paint is thermally cured by heat treatment (Comparative Example 1 is 100 ° C. for 30 minutes and Comparative Example 2 is 160 ° C. for 30 minutes). Each surface layer (thickness 8 μm) was formed. This produced the developing roll (three-layer structure) which concerns on Comparative Examples 1-2.

4). Developing roll characteristics evaluation (roll resistance)
Each developing roll is brought into line contact with the metal drum, and the metal drum is rotationally driven with a load of 500 g applied to both ends of the core of the roll. Each developing roll is rotated at 30 rpm and 100 V is applied. The electrical resistance between the metal core and the metal drum was measured as roll resistance.

(Toner adhesion resistance)
Toner adhesion resistance was evaluated by examining filming. The evaluation was performed according to the following procedure.

  Each developing roll is incorporated into a cartridge of a commercially available color laser printer (manufactured by Canon Inc., “LBP-2510”), and passes through an image in an environment of a temperature of 32.5 ° C. and a relative humidity of 80% RH. It was performed on 3000 sheets of paper (A4 size), and then the roll surface was magnified with a microscope ("VK-9510" manufactured by Keyence Corporation), and the appearance was observed.

  According to the above observation, when the toner surface does not adhere to the roll surface or it is slight, the toner adheres to the surface of the roll and the image is not resistant. “X” indicates that the toner adhesion is inferior.

(Abrasion resistance)
Each developing roll is incorporated into a cartridge of a commercially available color laser printer (manufactured by Canon Inc., “LBP-2510”), and passes through an image in an environment of a temperature of 32.5 ° C. and a relative humidity of 80% RH. The test was performed with 1000 sheets of paper (A4 size), and then the surface of the roll was magnified with a microscope ("VK-9510" manufactured by Keyence Corporation), and the appearance was observed.

  According to the above observation, the surface layer corresponding to the top position of the urethane particles, which are the roughness forming particles blended in the intermediate layer, is hardly scraped and the image is not disturbed as having good wear resistance. “O”, “X”, because the surface layer corresponding to the same position was shaved and the image was not smooth.

(Charge decay rate)
Under an environment of a temperature of 15 ° C. and a humidity of 10% RH, a corona current of 100 μA is applied to the surface of the developing roll using a corona discharge wire (corotron) while rotating each developing roll at a roll rotation speed of 70 rpm. The surface was charged. Then, the residual charge qs on the surface of the developing roll was measured by a surface potentiometer disposed at a position one quarter cycle behind the corona discharge line. Further, the residual charge qr 1 second after the application stop was measured. The measurement was performed while the roll was rotated. And charge decay rate = (qs-qr) / qsx100 (%) was computed from these values. This charge decay rate is an index of electrical responsiveness. The larger the value, the higher the electrical responsiveness.

  Here, the case where the charge decay rate is 80% or more is regarded as “◯” as being excellent in electrical response, and the case where the charge decay rate is less than 80% is regarded as being inferior in electrical response. × ”.

(Image evaluation)
Each developing roll is incorporated into a cartridge of a commercially available color laser printer (manufactured by Canon Inc., “LBP-2510”), and solid and halftone images are output in an environment of a temperature of 23 ° C. and a humidity of 53% RH. Went. The case where there was no afterimage or unevenness in the obtained image was indicated as “◯” as good image output, and the case where afterimage or unevenness occurred was indicated as “x” as poor image output.

  In Table 2, the evaluation result of the developing roll which concerns on an Example and a comparative example is put together with the compounding ratio and material characteristic of the electroconductive composition for surface layer formation, and is shown collectively.

  Comparing Table 2 shows the following. That is, since the developing roll according to Comparative Example 1 has a low surface tack (low friction coefficient μs), filming hardly occurs and wear resistance is also good. However, since it is electronically conductive, the roll resistance variation is large, the charge decay rate is small, and the electrical response is inferior. As a result, an image defect occurred. Therefore, it can be said that with this developing roll, it is difficult to cope with high image quality of electrophotographic equipment.

  Further, although the developing roll according to Comparative Example 2 has small roll resistance variation, the surface layer has a large friction coefficient μs, causes filming, and is inferior in toner adhesion resistance. In addition, image defects occurred. Therefore, it can be said that with this developing roll, it is difficult to cope with high image quality and long life of the electrophotographic apparatus.

  On the other hand, as for the image development roll which concerns on an Example, as for all, each surface layer is a hardened | cured material of the electroconductive composition containing both (A) component which is a polymerization component prescribed | regulated by this application, and (B) component. It has become.

  Thus, in addition to the component (A), when the component (B) is used, the hardness of the cured product becomes relatively high, the friction coefficient of the surface layer becomes small, and tackiness due to the component (A) is reduced. descend. Therefore, the toner adhesion resistance is improved, filming hardly occurs, and the durability can be improved.

  Moreover, since the hardness of hardened | cured material becomes comparatively high by using (B) component, the abrasion resistance of a surface layer can also be improved.

  Moreover, each electroconductive composition used for the Example hardens | cures rapidly by ultraviolet irradiation after application | coating. Therefore, the thickness of the surface layer formed on the convex portion (corresponding to the top position of the urethane particles that are the roughness forming particles) of the intermediate layer disposed in the lower layer of the surface layer is difficult to be reduced. For this reason, the surface layer thickness hardly changes due to the uneven shape of the urethane particles. Thereby, the surface layer in the upper part of the urethane particles is not easily worn out in a short period of time, and this can also improve the wear resistance.

  Further, since the surface layer made of the cured product is ionic conductive, the roll resistance variation is small, the charge decay rate is high, and the electrical response is high. Therefore, a good image can be obtained.

  Therefore, it has been confirmed that such a developing roll can easily cope with high image quality, high speed, and long life of an electrophotographic apparatus such as a printer or a copying machine in which the developing roll is incorporated.

  The embodiments and examples of the present invention have been described above, but the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. is there.

It is a circumferential direction sectional view showing an example of a development roll concerning this embodiment. FIG. 6 is a circumferential cross-sectional view showing another example of a developing roll according to the present embodiment. It is sectional drawing which expanded and showed typically an example of the intermediate | middle layer containing the particle | grains for roughness formation, and the surface layer formed on this.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Developing roll 12 Shaft body 14 Base layer 16 Intermediate layer 18 Surface layer 20 Roughness formation particle

Claims (6)

The surface layer is
(A) a (meth) acrylate monomer having an ethylene oxide unit introduced in the molecular structure;
(B) urethane (meth) acrylate,
A developing roll for an electrophotographic apparatus, comprising a cured product of an ultraviolet curable conductive composition comprising   2. The developing roll for an electrophotographic apparatus according to claim 1, wherein the component (A) / the component (B) (mass ratio) is in the range of 5/95 to 95/5.   3. The electrophotographic apparatus according to claim 1, wherein the number of (meth) acryloyl groups contained in one molecule of the (B) urethane (meth) acrylate is in the range of 1 to 6. 4. Development roll.   The developing roll for an electrophotographic apparatus according to any one of claims 1 to 3, wherein the ultraviolet curable conductive composition contains (C) an ionic conductive agent.   The shaft body, a base layer formed on the outer periphery of the shaft body, an intermediate layer formed on the outer periphery of the base layer, and the surface layer formed on the outer periphery of the intermediate layer. The developing roll for electrophotographic equipment according to any one of 1 to 4.   The developing roll for an electrophotographic apparatus according to claim 1, wherein the intermediate layer includes roughness forming particles.

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