JP2005031656A - Developing roller and electrophotographic apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller excellent in uniformity of triboelectrification to toner and in running stability, and to provide an electrophotographic apparatus having good developing efficiency and giving a high density, clear, little fogged, uniform image. <P>SOLUTION: The developing roller consists of a shaft having good conductivity and an elastic layer and one or more coating layers located in order on the periphery of the shaft, wherein a coating layer used as a surface layer contains a positive charge control resin obtained by copolymerizing copolymerizable monomers including a (meth)acrylic ester monomer having a ≥4C alkyl group and a (meth)acrylamide monomer having an amino group. The developing roller is located opposite to a surface of an electrostatic charge image carrier in contact with or in close vicinity to the surface to fabricate the image forming apparatus, and a negative charge type single component developer is used as a developer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a developing roller used in an electrophotographic apparatus and an electrophotographic apparatus using the same.

  Conventionally, as a developing method in an electrophotographic apparatus such as a copying machine or a laser beam printer, a one-component developer (toner) is thinly coated on a toner carrier by a toner regulating member, and an electrostatic charge image carrier (for example, a photosensitive member). There is known a one-component development method in which an electrostatic latent image on an electrostatic charge image carrier is developed by bringing it into contact with or in proximity to a drum) and transferring it from the toner carrier to the surface of the electrostatic image carrier. As the toner carrier used in such a development method, for example, a roller-shaped development roller in which an elastic layer is provided around a metal (core metal) and a surface coating layer is provided on the elastic layer as necessary, or elastic A developing sleeve without a layer is used.

  In this one-component development method, in order to stably obtain a uniform image with good development efficiency, high image density, clear and less fog, uniform triboelectric chargeability and durability stability to the toner of the developing roller is required. However, the current situation is that such a technique has not been fully realized.

  For example, when the developing roller rotates repeatedly, the toner deteriorates, and the charging ability and developing efficiency of the toner decrease, so that when the image density is low, or in a high-temperature and high-humidity environment, The amount of charge is significantly reduced, and fogging may occur.

  Recently, in order to further improve the image quality of electrophotography, the toner has been reduced in particle size and particle size. For example, in order to improve the resolution and sharpness of an image, in order to faithfully reproduce an electrostatic latent image, it is a trend to use a small toner having a particle diameter of 6 to 7 μm or less. In addition, efforts have been made to reduce the toner fixing point (melting temperature) to the limit for the purpose of shortening the first copy time and saving power. Under such circumstances, the toner is repeatedly exposed to physical stresses caused by the toner regulating member, the developing roller, etc. in the developing unit, and is also exposed to thermal stresses caused by such stress, so that the toner itself deteriorates. Also, this causes contamination of the surface of the developing member such as the developing roller and toner fusion, and as a result, it is difficult to impart uniform and stable charging properties to the toner.

Recently, a method using a charge control agent has been proposed. As a charge control agent, a method using a charge control resin soluble in an organic solvent has been proposed, and methods used for a developing sleeve (for example, Patent Document 1, Patent Document 2, and Patent Document 3) have been reported. All of these mainly use a copolymer of an amino group-containing monomer and methyl methacrylate as a charge control resin.
JP 2000-242033 A JP 2002-244426 A JP 2003-005507 A

  Even if the charge control resin described in the above document is applied to the developing roller, it is expected that the uniformity and durability stability of the triboelectric charge with respect to the toner can be improved to some extent, but in recent years the performance has been rapidly improved. In order to cope with the electrophotographic apparatus, further improvement in its characteristics is desired.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing roller having excellent frictional charging uniformity and durability stability with respect to toner, and having high development efficiency, high density, clear and uniform image with less fog. Is to provide.

  When the inventors actually synthesized charge control resins having various structures and applied them to the developing roller to confirm the effect, the charge control ability of the charge control resins having a specific structure is particularly remarkable. I found out.

  The present invention is a developing roller in which a highly conductive shaft and an elastic layer and one or more coating layers are sequentially provided on the outer periphery of the shaft, and a thin layer of a one-component developer is formed on the surface of the developing roller. In this state, in the developing roller that develops the electrostatic latent image on the electrostatic image carrier by contacting or approaching the electrostatic image carrier, the coating layer that becomes the surface layer of the developing roller has the following formula: It contains a positive charge control resin obtained by copolymerizing a (meth) acrylic acid ester monomer represented by (1) and a copolymerization monomer containing a monomer having an amino group represented by the following formula (2). Development roller.

(Wherein R ¹ represents an alkyl group having 4 or more carbon atoms, R ² represents a hydrogen atom or a methyl group, R ³ represents a divalent organic group having 1 to 7 carbon atoms, R ⁴ and R ⁵ are each a hydrogen atom or an organic group having 1 to 20 carbon atoms or a cyclic structure of R ⁴ and R ⁵ are 4-20 carbon atoms chemically bonded or, R ⁴ and R ⁵ are chemically bonded , A cyclic structure of 4 to 19 carbon atoms containing at least one of a nitrogen atom, an oxygen atom and a sulfur atom.)
The present invention also provides an electrostatic charge image bearing member, a charging device for charging the surface of the electrostatic charge image bearing member, and an electrostatic latent image for forming an electrostatic latent image in a charged region of the electrostatic charge image bearing member. An electrostatic latent image forming apparatus, and supplying a negatively chargeable one-component developer to an electrostatic latent image formed on the surface of the electrostatic charge image bearing member to visualize the electrostatic latent image into an image An electrophotographic apparatus having a developing device and a transfer device for transferring the image to a transfer material, wherein the developing roller included in the developing device is the developing roller. is there.

  By adopting the configuration as in the present invention, the developing roller is excellent in the uniformity and durability stability of the frictional development with respect to the toner. In addition, the electrophotographic apparatus can obtain a uniform image with good development efficiency, high density, clearness, and less fogging.

  The developing roller of the present invention comprises a highly conductive shaft, an elastic layer and one or more coating layers sequentially provided on the outer periphery thereof, and contains a positive charge control resin in the coating layer serving as the surface layer. Then, a thin layer of a one-component developer is formed and supported on the surface, and in this state, the electrostatic latent image on the electrostatic image carrier is developed by contacting or approaching the electrostatic image carrier. It can be used as a roller. With this positive charge control resin, the uniformity and durability stability of the frictional development with respect to the toner become excellent. Here, the charge control resin is a resin having a function of controlling the amount of charge generated by friction to an appropriate amount by being added to the resin. Specifically, a positive charge control resin having an amino group or the like and having a function of imparting a positive charge to the resin, and having a function of imparting a negative charge to the resin having a carboxyl group or a sulfonyl group. There is negative charge control resin.

  As the positive charge control resin used in the developing roller of the present invention, a copolymer monomer including a (meth) acrylic acid ester monomer represented by the following formula (1) and a monomer having an amino group represented by the following formula (2) is used. It is a positive charge control resin obtained by polymerization.

(Wherein R ¹ represents an alkyl group having 4 or more carbon atoms, R ² represents a hydrogen atom or a methyl group, R ³ represents a divalent organic group having 1 to 7 carbon atoms, R ⁴ and R ⁵ are each a hydrogen atom or an organic group having 1 to 20 carbon atoms or a cyclic structure of R ⁴ and R ⁵ are 4-20 carbon atoms chemically bonded or, R ⁴ and R ⁵ are chemically bonded , A cyclic structure of 4 to 19 carbon atoms containing at least one of a nitrogen atom, an oxygen atom and a sulfur atom.)
As the (meth) acrylic acid ester monomer represented by the formula (1), n-butyl (meth) acrylate, tert-butyl (meth) acrylate, iso-butyl (meth) acrylate, n-amyl (meth) acrylate, n -Hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, n-nonyl (meth) acrylate, n-lauryl (meth) ) Acrylate, n-tridecyl (meth) acrylate, n-stearyl (meth) acrylate, isobornyl (meth) acrylate and the like. "(Meth) acrylate" means methacrylate or acrylate (hereinafter the same). The (meth) acrylic acid ester monomer represented by the formula (1) can be used alone or in combination of two or more monomers.

R ¹ in Formula (1) is preferably an alkyl group having 4 or more carbon atoms, more preferably an alkyl group having 6 or more carbon atoms, and further preferably an alkyl group having 8 or more carbon atoms. R ¹ in formula (1) is preferably an alkyl group having 20 or less carbon atoms. R ¹ in Formula (1) may be a straight chain, may be branched, or may have a cyclic structure.

  The content of the (meth) acrylic acid ester monomer represented by the formula (1) is preferably 5 to 99% by mass of the copolymer monomer. When the content is 5% by mass or more, the solubility in a solvent and the compatibility with the base resin tend to be further increased, and when the content is 99% by mass or less, the triboelectric charge amount is sufficient. More preferably, it is 10-97 mass%.

  As the monomer having an amino group represented by the formula (2), N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide, pN, N-dimethylaminophenyl (meth) acrylamide, pN, N-diethylaminophenyl (meth) acrylamide, pN, N-dipropylaminophenyl (meta ) Acrylamide, pN, N-dibutylaminophenyl (meth) acrylamide, pN-laurylaminophenyl (meth) acrylamide, pN-stearylaminophenyl (meth) acrylamide, pN, N-dimethylaminobenzyl (Meth) acrylamide, -N, N-diethylaminobenzyl (meth) acrylamide, pN, N-dipropylaminobenzyl (meth) acrylamide, pN, N-dibutylaminobenzyl (meth) acrylamide, pN-laurylaminobenzyl (meta) ) Acrylamide, pN-stearylaminobenzyl (meth) acrylamide and the like. The monomer which has an amino group shown by Formula (2) can be used individually or in combination of 2 or more types of monomers. “(Meth) acrylamide” means methacrylamide or acrylamide (hereinafter the same).

R ³ in Formula (2) is preferably a divalent organic group having 2 to 4 carbon atoms. R ⁴ and R ⁵ in Formula (2) are each preferably a hydrogen atom or an organic group having 1 to 20 carbon atoms, and preferably an organic group having 1 to 4 carbon atoms. R ^{3 to} R ⁵ may be linear, branched, or may have a cyclic structure. .

  The content of the monomer having an amino group represented by the formula (2) is preferably 1 to 95% by mass of the copolymer monomer. By setting the amount to 1% by mass or more, the triboelectric charge amount is likely to be sufficient, and by setting the amount to 95% by mass or less, the solubility in a solvent and the compatibility with the base resin tend to be further increased. 3 to 90% by mass.

  Moreover, it is preferable that the sum total of the (meth) acrylic acid ester monomer shown by Formula (1) and the monomer which has an amino group shown by Formula (2) shall be 30-100 mass% of a copolymerization monomer. When the content is 30% by mass or more, the triboelectric charge amount tends to be sufficient. More preferably, it is 50-100 mass%.

  A monomer having an amino group represented by the following formula (10) can also be included as a copolymerization monomer for obtaining a positive charge control resin used in the developing roller of the present invention.

(Wherein R ³ represents a divalent organic group having 1 to 7 carbon atoms, R ⁴ and R ⁵ are each a hydrogen atom or an organic group having 1 to 20 carbon atoms, or R ⁴ and R ⁵ are chemical A cyclic structure having 4 to 20 carbon atoms bonded thereto, or a cyclic structure having 4 to 19 carbon atoms having at least one of a nitrogen atom, an oxygen atom and a sulfur atom chemically bonded to R ⁴ and R ⁵ , To express.)
As the monomer having an amino group represented by the formula (10), N, N-dimethylaminomethyl (meth) acrylate, N, N-diethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminobutyl (meth) acrylate, pN, N-dimethylaminophenyl (meth) acrylate, p -N, N-diethylaminophenyl (meth) acrylate, pN, N-dipropylaminophenyl (meth) acrylate, pN, N-dibutylaminophenyl (meth) acrylate, pN-laurylaminophenyl (meta ) Acrylate, pN-stearylaminophenyl (Meth) acrylate, pN, N-dimethylaminobenzyl (meth) acrylate, pN, N-diethylaminobenzyl (meth) acrylate, pN, N-dipropylaminobenzyl (meth) acrylate, pN, Examples thereof include N-dibutylaminobenzyl (meth) acrylate, pN-laurylaminobenzyl (meth) acrylate, pN-stearylaminobenzyl (meth) acrylate and the like. The monomer which has an amino group shown by Formula (10) can be used individually or in combination of 2 or more types of monomers.

R ³ in formula (10) is preferably a divalent organic group having 2 to 4 carbon atoms. R ⁴ and R ⁵ in Formula (10) are each preferably a hydrogen atom or an organic group having 1 to 20 carbon atoms, and preferably an organic group having 1 to 4 carbon atoms. R ^{3 to} R ⁵ may be linear, branched, or may have a cyclic structure. .

  The monomer having an amino group represented by the formula (10) is preferably used in an amount not exceeding 50% by mass of the copolymerization monomer. Furthermore, it is desirable not to exceed the content of the monomer having an amino group represented by the formula (2).

  The copolymerization monomer for obtaining the positive charge control resin used for the developing roller of the present invention may contain other monomers copolymerizable therewith in addition to the monomer as described above. Examples of other copolymerizable monomers include (meth) acrylic acid ester monomers having an alkyl group having 1 to 3 carbon atoms; styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methyl Styrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, p -Styrene monomers such as n-decyl styrene, pn-dodecyl styrene, p-methoxy styrene; vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl formate; vinyl methyl ether, Vinyl ether-based compounds such as vinyl ethyl ether and vinyl isobutyl ether And vinyl ketone monomers such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropyl ketone, etc., and may be appropriately determined according to the physical properties required for the developing roller. The other copolymerizable monomers can be used alone or in combination of two or more monomers.

  The other copolymerizable monomer is preferably in an amount not exceeding 70% by mass of the copolymerized monomer.

  The polymerization method for obtaining the positively chargeable control resin used in the developing roller of the present invention is not particularly limited, and examples thereof include a bulk polymerization method, a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method. . The solution polymerization method is preferable from the viewpoint that the reaction can be easily controlled. The solvent used in the solution polymerization method is not particularly limited, but xylene, toluene, ethyl acetate, isobutyl acetate, isopropyl alcohol, methanol, methyl ethyl ketone, methyl isobutyl ketone, N, N-dimethylformamide, dimethylformamide, etc. Is used. The ratio of the solvent and the copolymerization monomer at that time is not particularly limited, but it is preferably 30 to 400 parts by mass of the copolymerization monomer with respect to 100 parts by mass of the solvent.

  The polymerization initiator used for polymerizing the positively chargeable control resin used in the developing roller of the present invention is not particularly limited. For example, t-butyl peroxy-2-ethylhexanoate, cumyl perpivalate, t-butyl peroxylaurate, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, di-t-butyl peroxide, t -Butylcumyl peroxide, dicumyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethyl) Valeronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate), and the like. It can be used in combination with two or more species.

  The polymerization initiator is preferably 0.05 to 30 parts by mass (more preferably 0.1 to 15 parts by mass) with respect to 100 parts by mass of the comonomer. The temperature of the polymerization reaction is not particularly limited, and can be set according to the solvent to be used, the polymerization initiator, and the copolymerization monomer, but is preferably 40 ° C to 150 ° C.

  The positive charge control resin used in the developing roller of the present invention preferably has an amino value of 5 to 350 mgKOH / g, more preferably 50 to 325 mgKOH / g, and still more preferably 200 to 300 mgKOH / g. If the amino value of the positively chargeable control resin is less than 5 mgKOH / g, the charge amount may be insufficient, and if it exceeds 350 mgKOH / g, the compatibility with the main binder tends to decrease. The amount of charge may be insufficient.

  The weight average molecular weight (Mw) of the positively chargeable control resin used in the developing roller of the present invention is preferably 2000 to 500000, more preferably 3000 to 300000, and still more preferably 5000 to 200000. If Mw is less than 2000, the bleed out may occur over time. If it exceeds 500,000, the compatibility with the main binder tends to decrease.

  The glass transition temperature (Tg) of the positive charge control resin used in the developing roller of the present invention is preferably about −100 to 180 ° C., more preferably −90 to 170 ° C., and further preferably −80 to 160. This is the case at ° C. If Tg is less than −100 ° C., the tackiness is large and the friction coefficient may be large. When it exceeds 180 ° C., the dispersion state of the positively chargeable control resin in the main binder may not be uniform.

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

  FIG. 1 shows an outline of one embodiment of the developing roller of the present invention. FIG. 1A is a schematic sectional view along the axis of the developing roller, and FIG. 1B is a view of the developing roller viewed from the axial direction. The developing roller 114 in the form shown in this figure is provided with an elastic layer 114b and a single coating layer 114c on the outer periphery of a cored bar 114a serving as a highly conductive shaft.

  The cored bar 114a only needs to have a strength that can be withstood during molding or actual use, and its outer diameter is preferably 4 to 10 mm. As the material of the core metal, for example, metals such as iron, aluminum, titanium, copper and nickel, alloys such as stainless steel, duralumin, brass and bronze containing these metals, and composites in which carbon black and carbon fibers are hardened with plastic. Examples thereof include a material that is rigid and exhibits conductivity.

  The elastic layer 114b may be formed of a known material, such as natural rubber, silicone rubber, urethane rubber, ethylene propylene rubber, butadiene rubber, chloroprene rubber, neoprene rubber, isoprene rubber, NBR, etc. Carbon black, graphite, conductive particles, conductive rubber and the like can be used as necessary. The elastic layer 114b preferably has conductivity. The thickness of the elastic layer 114b is preferably 2.0 to 10 mm. If it is too thick, the resistance value tends to be high, and if it is too thin, the hardness is difficult to be sufficiently lowered.

  The coating layer 114c is a surface layer of the developing roller 114, and is formed of a coating layer forming material obtained by mixing the above-described positive charge control resin with a base resin. The above-mentioned positive charge control resin is preferably contained in the coating layer forming material in an amount of 0.01 to 50% by mass, and more preferably 0.05 to 30% by mass.

  As the base resin, known resins can be used. Styrene resin (monopolymer or copolymer containing styrene or styrene-substituted product), acrylic resin (monopolymer or copolymer containing (meth) acrylic acid ester) ), Vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, fluorine resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, nylon resin, silicone Examples thereof include resins, ketone resins, ethylene-ethyl acrylate copolymers, xylene resins, and polyvinyl butyral resins. Particularly preferable base resins in the practice of the present invention are urethane resin, nylon resin, acrylic resin, fluororesin and the like because they require wear resistance, toner chargeability, toner transportability and the like. One type or two or more types of base resins may be used.

  Further, it is desirable to add carbon black to the coating layer forming material as a resistance adjusting material. Examples of the carbon black used for such purposes include furnace black, lamp black, thermal black, acetylene black, channel black, and the like. The amount of carbon black in the coating layer forming material can be appropriately set according to the characteristics of the target developing roller, and can be contained, for example, in an amount of about 1 to 40% by mass.

  Furthermore, it is preferable to add insulating particles having an average particle diameter of 3 to 30 μm, for example, urethane particles, nylon particles, acrylic particles, silicone particles, etc., to the coating layer forming material as the surface roughening material. The amount of the surface roughening material in the coating layer forming material can be appropriately set according to the characteristics of the intended developing roller, and can be contained, for example, in an amount of about 2 to 50% by mass.

  The coating layer forming material containing the above-mentioned components is a spray coating method, a dipping method, etc., which is a paint dispersed using a conventionally known dispersing device using beads such as a sand mill, paint shaker, dyno mill, pearl mill, etc. Is applied to the surface of the elastic layer to form a coating layer. For example, methyl ethyl ketone, toluene, alcohol or the like can be used as the solvent used in the paint.

  The thickness of the coating layer is preferably 2 to 100 μm in consideration of realizing high wear resistance without impairing the flexibility of the elastic layer. More preferably, it is 5-30 micrometers.

  Although the above example is a developing roller having one coating layer, it can also be a developing roller having two or more coating layers. In that case, the above-mentioned positive charge control resin should just be contained in the coating layer which forms a surface layer at least. In the case of the embodiment in which the above-described positive charge control resin is not included in the inner coating layer, it can be the same as the above configuration except that the charge control resin is not included. Two or more coating layers may have the same configuration or different configurations with respect to materials used, composition ratios, and the like.

  Next, the electrophotographic apparatus of the present invention will be described. The electrophotographic apparatus of the present invention uses the developing roller of the present invention and a negatively chargeable one-component developer. More specifically, an electrostatic charge image carrier, a charging device for charging the surface of the electrostatic charge image carrier, and an electrostatic image for forming an electrostatic latent image in a charged region of the electrostatic charge image carrier. An electrostatic latent image forming apparatus, and supplying a negatively chargeable one-component developer to an electrostatic latent image formed on the surface of the electrostatic charge image bearing member to visualize the electrostatic latent image into an image An electrophotographic apparatus having a developing device and a transfer device for transferring the image to a transfer material, wherein the developing roller included in the developing device is the developing roller. is there. Such an electrophotographic apparatus of the present invention has a good development efficiency, a high density, a clear and uniform image with little fog.

  A schematic configuration of the electrophotographic apparatus (laser beam printer) of the present invention is shown in FIG. In FIG. 2, the developing device 10 of the laser beam printer uses a non-magnetic one-component developing system. In the developer container 12, a developer 11 (one-component developer made of a negatively charged non-magnetic toner) is accommodated, and the developer container 12 facing the photosensitive drum 1 as an electrostatic charge image carrier. A developing roller 24 is installed in the opening of the photosensitive drum 1 so as to be in contact with the photosensitive drum 1. As described above, the developing roller 24 is formed by forming the elastic layer 24b and the coating layer 24c on the cored bar 24a. Further, a supply roller 25 in which an elastic layer 25 b and a coating layer 25 c are formed on the core metal 25 a is installed in a state where the developer 11 can be supplied to the development roller 24.

  When the developing roller 24 and the supply roller 25 rotate in the direction of the arrow, the developer 11 in the developer container 12 is carried on the developing roller 24. The developer 11 is regulated by the blade 16, and a thin layer 11 a of developer is formed on the developing roller 24, and only the developer is conveyed to the developing area 13 facing the photosensitive drum 1. On the other hand, the surface of the photosensitive drum 1 is primarily charged by the charging roller 19 provided in the charging device, and an electrostatic latent image is formed by the laser beam L emitted from the laser beam transmitting means provided in the electrostatic latent image forming device. ing. A developing bias is applied between the developing roller 24 and the photosensitive drum 1 by a constant voltage power source 18, and a developer is supplied to the electrostatic latent image on the photosensitive drum 1 and developed. Thereafter, the developed image is transferred to a transfer material such as paper by a transfer device (not shown), and fixed to the transfer material by a fixing device (not shown), thereby obtaining a printed matter in which the image is printed on the transfer material. .

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by an Example. (3) to (7) are structural formulas of (meth) acrylic acid ester monomers A1 to A5 [A1 to A4: those represented by the above formula (1), A5: methyl methacrylate] used in Examples. The structural formulas of monomers B1 to B2 having an amino group are shown in (8) to (9) [shown by the above formula (2)].

[Example 1]
(Production of positive charge control resin CCR1 and evaluation of physical properties)
In a four-necked separable flask equipped with a stirrer, a cooler, a thermometer and a nitrogen inlet tube, 15 g of n-lauryl methacrylate (A4) and 35 g of N, N-dimethylaminopropylacrylamide (B1) as a copolymerization monomer, Positive charge control by charging 50 g of methyl ethyl ketone and 2.0 g of dimethyl 2,2′-azobis (2-methylpropionate) as a polymerization initiator, and performing solution polymerization for 8 hours under reflux with introduction of nitrogen while stirring. A solution of resin CCR1 was obtained. Thereafter, a part of the solution of CCR1 was dried under reduced pressure and used for measurement of physical properties.

  The amino value, weight average molecular weight (Mw), and Tg of the obtained CCR1 were respectively determined using a fully automatic titrator (AT-510 (trade name) manufactured by Kyoto Electronics Industry Co., Ltd.) and GPC measurement (apparatus: manufactured by Tosoh Corporation). It was measured by HLC-8120GPC (trade name), column: KF-805L (trade name) x 2 manufactured by Showa Denko KK, DSC measurement (DSC 6200 (trade name) manufactured by Seiko Instruments Inc.). The results are shown in Table 1.

(Manufacture of developing roller 1)
An 8 mm outer diameter metal core (manufactured by SUM) is placed concentrically in a cylindrical mold with an inner diameter of 16 mm, and a liquid conductive silicone rubber (manufactured by Toray Dow Silicone, Asker C hardness 35 degrees, volume resistivity 10 × 10 ⁹ Ωcm) is cast, placed in an oven at 130 ° C. and heat-molded for 20 minutes. After demolding, secondary vulcanization is performed in an oven at 200 ° C. for 4 hours, and an elastic layer having a thickness of 4 mm is placed around the core metal. Formed.

  Next, urethane paint (trade name: Nipponporan N5033, manufactured by Nippon Polyurethane Co., Ltd.) is diluted with methyl ethyl ketone so that the solid content concentration is 10% by mass, and the positive charge control resin CCR1 is added to 100 parts by mass of the solid content of the urethane paint. 10 parts by mass, 50 parts by mass of carbon black (trade name: # 7360SB, manufactured by Tokai Carbon Co., Ltd.) as a resistance adjusting material, and urethane particles having an average particle diameter of 14 μm (trade name: Art Pearl C400, manufactured by Negami Kogyo Co., Ltd.) 6 parts by mass was added. It is obtained by adding 10 parts by mass of a curing agent (modified TDI, trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) to 100 parts by mass of the solid content of the urethane paint, and stirring the mixture in which each component is sufficiently dispersed. The coating layer is formed by dipping the coated paint on the previously molded elastic layer to a dry film thickness of 20 μm, drying in an oven at 80 ° C. for 15 minutes, and curing in an oven at 140 ° C. for 4 hours. A development roller 1 was obtained.

(Evaluation of developing roller 1)
The developing roller 1 obtained above is attached to an evaluation laser beam printer using a one-component developer made of a negatively charged non-magnetic toner, and is predetermined in an environment of 32.5 ° C. × 80% RH (HH). After continuously printing 10,000 images (character pattern images), the charge amount, image density and fog of the toner adhering to the developing roller were evaluated. The results are shown in Table 2.

[Examples 2 to 4, Comparative Example 1]
(Production of positive charge control resins CCR2 to 5 and evaluation of physical property values)
Positive charge control resins CCR2 to 5 were obtained in the same manner as in Example 1 except that a (meth) acrylic acid ester monomer and a monomer having an amino group were used according to Table 1. The weight average molecular weight (Mw), Tg, and amino value of the obtained CCR2 to 5 were measured in the same manner as in Example 1. The results are shown in Table 1.

(Manufacture of developing rollers 2 to 5)
Developing rollers 2 to 5 were manufactured in the same manner as the manufacturing method of the developing roller 1 of Example 1 except that CCR 2 to 5 were used instead of CCR1.

(Evaluation of developing rollers 2 to 5)
Evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 2]
(Manufacture of developing roller 6)
Except not using CCR1, the developing roller 6 which does not contain positive charge control resin in a coating layer was manufactured similarly to the manufacturing method of the developing roller 1 of Example 1.

(Evaluation of developing roller 6)
Evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

1) Charge amount The toner carried on the developing roller was sucked into a container having a predetermined shape, a change in the charge amount of the container was read with a coulomb meter connected to the container, and the sucked toner was measured. The charge amount of the toner was obtained by dividing the charge amount of the sucked toner by the sucked toner mass.

2) Color image test The printer is stopped during the output of the solid white image, the toner adhering to the photoconductor is peeled off with the tape, and the reflection measurement device REFECTRECTER (trade name, Tokyo Denshoku Co., Ltd.) for fog measurement is used. The whiteness of the image white background portion after the initial durability and after the durability was measured, and the fog density was calculated and evaluated from the difference between the whiteness and the whiteness of the plain paper (transfer paper).

[Evaluation of fog]
A: Very good (less than 1.0%)
B: Good (1.0% or more and less than 2.0%)
C: Bad (2.0% or more)
Further, a black solid image was output, and the image density was measured using a Macbeth densitometer RD-918 (trade name, Sakata Inx Co., Ltd.).

[Evaluation of image density]
A: Very good (1.4 or more)
B: Good (1.2 or more and less than 1.4)
C: Bad (less than 1.2)
In Examples 1 to 4, the charge amount was high, the image density and the fog evaluation results were both good, and the uniformity of friction development with respect to the toner and the durability stability were excellent. Among them, in Examples 1 to 3 using the (meth) acrylic acid alkyl ester monomer having an alkyl group having 6 or more carbon atoms, the evaluation results of the image density and fog are very good, and the line is not thin. A good image was obtained.

It is a figure which shows the basic composition of the developing roller of this invention, (a) is a schematic sectional drawing along the axial line of the developing roller, (b) is the figure which looked at the developing roller from the axial direction. It is a schematic block diagram which shows the laser beam printer provided with the developing roller of this invention.

Explanation of symbols

1: photosensitive drum 10: developing device 11: developer 11a: developer thin layer 12: developer container 13: developing region 16: blade 18: constant voltage power supply 19: charging roller 24: developing roller 24a: cored bar 24b: Elastic layer 24c: coating layer 25: supply roller 25a: core metal 25b: elastic layer 25c: coating layer 114: developing roller 114a: core metal 114b: elastic layer 114c: coating layer L: laser beam

Claims (3)

A developing roller in which a highly conductive shaft and an elastic layer and one or more coating layers are sequentially provided on the outer periphery of the shaft, and a thin layer of a one-component developer is formed on and supported on the surface. In the developing roller that develops the electrostatic latent image on the electrostatic charge image carrier by contacting or approaching the electrostatic charge image carrier, the coating layer serving as the surface layer of the development roller is represented by the following formula (1): A developing roller comprising a positive charge control resin obtained by copolymerizing a (meth) acrylic acid ester monomer shown and a copolymerization monomer containing a monomer having an amino group shown by the following formula (2) .

(Wherein R ¹ represents an alkyl group having 4 or more carbon atoms, R ² represents a hydrogen atom or a methyl group, R ³ represents a divalent organic group having 1 to 7 carbon atoms, R ⁴ and R ⁵ are each a hydrogen atom or an organic group having 1 to 20 carbon atoms or a cyclic structure of R ⁴ and R ⁵ are 4-20 carbon atoms chemically bonded or, R ⁴ and R ⁵ are chemically bonded , A cyclic structure of 4 to 19 carbon atoms containing at least one of a nitrogen atom, an oxygen atom and a sulfur atom.) The developing roller according to claim 1, wherein R ¹ in the formula (1) is an alkyl group having 6 or more carbon atoms. An electrostatic charge image carrier, a charging device for charging the surface of the electrostatic charge image carrier, and an electrostatic latent image forming device for forming an electrostatic latent image on a charged region of the electrostatic charge image carrier; A developing device for supplying a negatively chargeable one-component developer to the electrostatic latent image formed on the surface of the electrostatic image bearing member to visualize the electrostatic latent image into an image; and An electrophotographic apparatus having a transfer device for transferring the toner to a transfer material, wherein the developing roller of the developing device is the developing roller according to claim 1.

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