JP2010152125A - Developing roller, process cartridge, image forming apparatus, and method for manufacturing developing roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller that is satisfactory in roller dimension accuracy and surfaceness, uniform in electric resistance and hardness, and can be recycled after use. <P>SOLUTION: The developing roller bears toner, and supplies toner to the surface of an image carrier on which a latent image is formed, thereby developing the electrostatic latent image. The developing roller comprises an axial core, and at least one elastic layer formed on the peripheral face of the axial core. The elastic layer contains thermoplastic elastomer. In addition, when measurement is made using an elastic layer cut out from the developing roller, T1 (L) representing a temperature (°C) at which viscosity is 5.0×10<SP>3</SP>Pa s and T1(H) representing a temperature (°C) at which viscosity is 5.0×10<SP>4</SP>Pa s satisfy the relation expressed by formula (1): 5°C≤T1(L)-T1(H)≤20°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing roller used in contact with a latent image carrier (photosensitive drum) incorporated in an image forming apparatus employing a copying machine, a printer or a facsimile, or an electrophotographic system, a process cartridge, and image formation Relates to the device. The present invention also relates to a method for manufacturing the developing roller.

  An image forming apparatus such as a copying machine, a facsimile machine, or a printer has an elastic roller having electrical conductivity (electric resistance) suitable for the purpose in order to charge a photosensitive drum or to visualize an electrostatic latent image. Commonly used. In the one-component developing type image forming apparatus, the electrostatic latent image is visualized, that is, developed by moving the toner from the developing roller to the photosensitive drum. Since the developing roller used in such an image forming apparatus carries the toner thinned by the regulating member, it needs to have a dimensional accuracy of the outer diameter corresponding to the regulating member and a uniform surface property. is there.

  A developing roller is generally used in which an elastic layer made of a rubber material imparted with conductivity is formed on the outer peripheral surface of a shaft core. Various methods have been disclosed and implemented regarding the method of creating the developing roller. As one method for obtaining the dimensional accuracy of the outer diameter and uniform surface properties, molding using a high-precision mold is performed. is there. Materials used for molding using a mold can be roughly classified into two types, thermosetting materials and thermoplastic materials.

  In a thermosetting material, a developing material is formed by pouring a liquid or a material that exhibits fluidity when heated into a mold, heat-curing and crosslinking, and then removing the material from the mold (Patent Document 1). ). In order to make it harden | cure, since the heating apparatus is required and energy is also consumed, it became a subject as productivity.

  On the other hand, a thermoplastic material does not require a heat curing step for cross-linking, and can be molded in a short time, which is a production advantage. In addition, the thermoplastic material can be reused even after use, and is an environmentally friendly material that can reduce waste. In the molding using a resin or elastomer which is a thermoplastic material, it is necessary to pay attention to the flow characteristics of the material in order to achieve a desired shape. Until now, as a charging roller (charging member) used for electrophotography, there has been disclosed a charging roller that can be easily molded with less environmental fluctuation by using a material having a melt flow index of the material within a certain range ( Patent Document 2).

  When an elastic roller is used as a developing roller, not only dimensional accuracy but also hardness, deformation recovery property, and surface uniformity corresponding to the regulating member are required at the same time. That is, particularly in contact development, the developing roller needs to be pressed against the photosensitive drum with a predetermined contact width, is easily deformed, and at the same time has excellent deformation recovery (set recovery), and is a semiconductive region. The electrical resistance characteristic is required.

Furthermore, from the viewpoint of resource saving and energy saving in recent years, it is desired to recycle the developing roller. For this purpose, an elastic layer that can be recycled is desired.
JP 2002-055522 A Japanese Patent Laid-Open No. 7-295328

  The present invention has been made in view of such a state of the art. That is, the present invention has a shaft core body and at least one elastic layer on the outer peripheral surface of the shaft core body, has good roller dimensional accuracy and surface property, uniform electrical resistance and hardness, and is used. An object of the present invention is to provide a developing roller that can be recycled later.

  In addition, the present invention provides a process cartridge and an image forming apparatus having such a developing roller, which are free from vertical streaks and unevenness of image density due to pressure unevenness with a regulating member, and can cope with high image quality of the image forming apparatus. There is to do.

  Another object of the present invention is to provide a developing roller manufacturing method having a stable average outer diameter during repeated molding and excellent productivity.

  As a result of diligent research and examination to solve the above-mentioned problems, the inventors measured the viscosity of the elastic layer cut out from the elastic layer, and when having a certain relationship, the outer diameter stability, The inventors have found that it is excellent in productivity, surface properties, etc., and finally completed the present invention.

That is, according to the present invention, in a developing roller that carries toner and supplies the toner to the surface of the image carrier on which the electrostatic latent image is formed, and visualizes the electrostatic latent image, the shaft core and the shaft It comprises at least one elastic layer on the outer peripheral surface of the core, and the elastic layer contains a thermoplastic elastomer and has a viscosity when measured with an elastic body cut out from the elastic layer. Temperature (° C.) at which 5.0 × 10 ³ Pa · s is obtained: T1 (L), Temperature (° C.) at which the viscosity is 5.0 × 10 ⁴ Pa · s: T1 (H) is represented by the following formula (1) The developing roller is characterized by satisfying the relationship.
5 ° C. ≦ T1 (L) −T1 (H) ≦ 20 ° C. Formula (1)

  According to the present invention, in the developing roller having at least one elastic layer, the developing roller has good roller dimensional accuracy and surface property, and uniform resistance and hardness as a roller. Further, in the process cartridge and the image forming apparatus using the developing roller of the present invention, there are no vertical streaks or unevenness in image density due to pressure unevenness with the regulating member, and good images can be obtained continuously over time. Further, the developing roller as described above can be easily produced at low cost. Furthermore, the developing roller used easily by the same manufacturing method can be reused.

  Hereinafter, the present invention will be described in more detail.

The developing roller of the present invention is a roller for carrying toner and supplying the toner to the surface of the latent image carrier on which the electrostatic latent image is formed, and revealing the electrostatic latent image. It comprises at least one elastic layer formed on the outer peripheral surface of the shaft core. The elastic layer contains a thermoplastic elastomer. And when it measures with the elastic body layer cut out from the developing roller, the temperature (° C.) at which the viscosity is 5.0 × 10 ³ Pa · s: T1 (L), the viscosity is 5.0 × 10 ⁴ Pa · s. Temperature (° C.): T1 (H) satisfies the relationship of the following formula (1).
5 ° C. ≦ T1 (L) −T1 (H) ≦ 20 ° C. Formula (1)

  When the elastic layer satisfies the relationship of the above formula (1), the developing roller has excellent dimensional accuracy and surface property, and also has excellent uniformity in electrical resistance and hardness, and uneven pressure with the regulating member. Therefore, a good image can be continuously obtained over time without vertical stripes and unevenness of image density. Thereby, when incorporated in a process cartridge or an image forming apparatus as a developing roller, good performance is exhibited.

  An example of the developing roller of the present invention is shown in FIG. 1 (perspective view) and FIG. 2 (cross-sectional view). The developing roller 1 has a shaft core body 11 at the center and a structure in which an elastic body layer 12 and a coating layer 13 are laminated on the outer peripheral surface thereof.

  The shaft core 11 usually has a cylindrical shape and is made of a conductive material such as metal. The developing roller used in the image forming apparatus is generally used with an electrical bias applied or grounded, and the shaft core 11 is a support member. It functions as an electrode of the developing member. The shaft body 11 is made of a metal or alloy such as aluminum, copper alloy or stainless steel, iron plated with chromium or nickel, a synthetic resin made conductive, etc., and at least its outer peripheral surface is formed thereon. The elastic layer is made of a conductive material sufficient to apply a predetermined voltage. In the developing roller used in the image forming apparatus, the outer diameter of the shaft core is usually in the range of 4 mm to 10 mm.

The elastic body layer 12 has flexibility and is formed using a material containing a thermoplastic elastomer as a main component of a raw material. The elastic body layer 12 has a temperature (° C.) at which the viscosity measured by an elastic body cut out from the elastic body layer is 5.0 × 10 ³ Pa · s: T1 (L), and the viscosity is 5.0 × 10 ^4. Temperature (° C.) at which Pa · s is obtained: T1 (H) needs to satisfy the relationship of the following formula (1).
5 ° C. ≦ T1 (L) −T1 (H) ≦ 20 ° C. Formula (1)

<Measurement of T1 (L) and T1 (H)>
T1 (L) and T1 (H) are obtained as follows.

An elastic body cut into a 2 mm square cube shape from the elastic layer is used as a measurement sample, and a flow tester CFT-500D (trade name, manufactured by Shimadzu Corporation) is used to measure the outflow amount under the following conditions.
Die hole diameter: 0.5mm
Die length: 1.0 mm
Cylinder pressure: 4.903 × 10 ⁵ (Pa)
Measurement mode: Temperature rising method Preheating time: 300 seconds Temperature rising rate: 3.0 ° C / min
Temperature range: 50 ° C to 300 ° C

As the temperature of the sample is increased at a constant speed, the sample is gradually heated and starts to flow out from the hole in the center of the sample table. When the temperature is further raised, the sample in a molten state largely flows out, and the descent of the blanker stops and ends. A temperature-viscosity curve is created from the apparent viscosity obtained when the amount of effluent at each temperature is measured. Temperature was created - from the viscosity curve, the temperature at which the viscosity becomes ^{5.0 × 10 3 Pa · s (} T1 (L)), the temperature at which the viscosity becomes 5.0 × 10 ⁴ Pa · s to (T1 (H)) Ask.

  When {T1 (L) -T1 (H)} is 5 ° C. or more and 20 ° C. or less, the developing roller is excellent in dimensional accuracy and surface property, and also in uniformity in electrical resistance and hardness. . That is, when {T1 (L) -T1 (H)} exceeds 20 ° C., sufficient dimensional accuracy cannot be obtained as a developing roller, and sufficient smoothness on the outer peripheral surface of the elastic layer when injection molding is performed. Cannot be obtained. On the other hand, when {T1 (L) -T1 (H)} is less than 5 ° C., the influence of the shearing history during molding tends to remain, the electric resistance of the developing roller is not stable, and the electric resistance unevenness tends to increase. is there. Within the above range, the smaller the value of {T1 (L) −T1 (H)}, the better the dimensional accuracy, and the more preferable is 5 ° C. or more and 15 ° C. or less.

  The influence of {T1 (L) -T1 (H)} on the dimensional accuracy of the developing roller can be considered as follows. That is, when molding is performed, the material has a viscosity suitable for the apparatus specifications and conditions, and the conditions are selected. As described above, T1 (L) correlates with a temperature at which the material has sufficient fluidity during molding under certain apparatus specifications and conditions. Similarly, T1 (H) correlates with the temperature at which the mobility of the molded material is stable. Molding with good dimensional accuracy is possible because the material is molded in a short period of time with sufficient fluidity and the mobility is stabilized in a short period of time. In general injection molding, the temperature of the material is usually lowered in the process of injecting the material into the mold, and considering the balance with productivity, {T1 (L) −T1 (H)} The value of must be set.

  Further, T1 (H) is preferably 120 ° C. or higher and 145 ° C. or lower. When T1 (H) is 120 ° C. or higher, in a temperature range (10 ° C. to 35 ° C.) where a developing roller is often used, the elasticity of the elastic layer is low and changes in physical properties due to oil component seepage or migration. It is difficult to receive. When T1 (H) is 145 ° C. or lower, the aggregation state of the carbon black and the rubber component in the elastic layer hardly changes, the shape accuracy of the developing roller is improved, and the resistance and hardness are stabilized.

  The term “thermoplastic elastomer” as used in the present invention refers to a material that exhibits rubber properties in the operating temperature range and is capable of plastic deformation at high temperatures. The thermoplastic elastomer has a hard segment and a soft segment, and a hard segment resin element is developed in a high temperature environment, and a soft segment rubber elastic element is developed in a low temperature environment.

  In the present invention, olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, ester-based thermoplastic elastomers, and urethane-based thermoplastic elastomers can be used as the thermoplastic elastomer.

  Any commercially available olefinic thermoplastic elastomer can be used as the olefinic thermoplastic elastomer. Specific examples include resins such as polyethylene, polypropylene, ethylene-ethyl acrylate resin, ethylene-vinyl acetate resin, ethylene-methacrylic acid resin, metallocene-catalyzed polyethylene, and metallocene-catalyzed polypropylene. Further, an elastomer composed of a copolymer of ethylene, propylene and a diene component, for example, an ethylene-propylene copolymer (EPM) or an ethylene-propylene-diene copolymer (EPDM) can also be used.

  As the styrenic thermoplastic elastomer, the following can be used. Styrene-butadiene-styrene block copolymer (SBS) and hydrogenated product thereof, styrene-isoprene-styrene block copolymer (SIS) and hydrogenated product thereof, styrene-isoprene-butadiene-styrene block copolymer (SIBS) And its hydrogenated product, styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer ( SEEPS).

  The hydrogenated product of SBS is a copolymer obtained by hydrogenating the double bond portion of the butadiene unit of SBS, and includes, for example, SEBS. The hydrogenated product of SIS is a copolymer obtained by hydrogenating the double bond portion of the isoprene unit of SIS, and includes, for example, SEPS. The hydrogenated product of SIBS is a copolymer obtained by hydrogenating double bond portions of butadiene units and isoprene units of SIBS, and includes, for example, SEEPS.

  Examples of the ester-based thermoplastic elastomer include a copolymer having an aromatic polyester unit as a hard segment and an aliphatic polyether unit or an aliphatic polyester unit as a soft segment. The aromatic polyester unit is composed of an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, or an ester thereof, and a glycol having 1 to 25 carbon atoms or an ester-forming derivative thereof. It is formed. In addition, as a C1-C25 glycol, ethylene glycol and 1, 4- butanediol are mentioned as a preferable thing.

  As the aliphatic polyether unit constituting the soft segment, for example, polyalkylene ether glycols such as poly (ethylene oxide) glycol and poly (tetramethylene oxide) glycol can be used. As the aliphatic polyester unit constituting the soft segment, for example, a polymer of a lactone such as caprolactone, enanthlactone, or caprylolactone can be used.

  The urethane-based thermoplastic elastomer generally has a polyurethane structure as a hard segment, and has a polyester polyol or polyether polyol unit as a soft segment. The polyurethane structure generally comprises a diisocyanate and a polyhydric alcohol or amine as a chain extender. In the present invention, the polyol unit and the chain extender are not particularly limited, and those generally used for urethane thermoplastic elastomers can be appropriately used.

  Here, the polyol unit is not particularly limited, and examples thereof include a polyester polyol, a polyether polyol, a copolyester polyol, and a polycarbonate polyol. More specifically, the following can be mentioned. Polycaprolactone glycol, poly (ethylene-1,4-adipate) glycol, poly (butylene-1,4-adipate) glycol as polyester polyol; polyoxytetramethylene glycol as polyether polyol; Diethylene glycol adipate) glycol; (hexanediol-1,6-carbonate) glycol as a polycarbonate-based polyol. These number average molecular weights are preferably 600 or more and 5,000 or less, particularly 1,000 or more and 3,000 or less.

  Examples of the diisocyanate include the following. For example, aromatic diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), tolidine diisocyanate (TODI), naphthalene diisocyanate (NDI); for example, hexamethylene diisocyanate (HDI), 2, 2, 4 and / or 2 , 4,4-trimethylhexamethylene diisocyanate (TMDI), lysine diisocyanate (LDI) and the like; for example, 4,4′-dicyclohexylmethane diisocyanate (H12MDI), isophorone diisocyanate (IPDI), 1,3-bis ( Cycloaliphatic diisocyanates such as isocyanate methyl) cyclohexane (H6XDI), trans-1,4-cyclohexane diisocyanate (CHDI). Among these, HDI, H12MDI, H6XDI, and CHDI are particularly preferable from the viewpoint of excellent resistance to discoloration (yellowing resistance).

  As the chain extender, polyhydric alcohols or amines can be usually used, and the following can be exemplified. 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-propylene glycol, 1,6-hexyl glycol, 1,3-butylene glycol, dicyclohexylmethanediamine (hydrogenated MDA), isophoronediamine (IPDA), etc. .

  Among these thermoplastic elastomers, those containing a crosslinked rubber component as the soft segment are desirable because preferable characteristics, so-called rubber elasticity, can be easily obtained. Examples of the crosslinked rubber component include the following. Ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR) , Chloroprene rubber (CR), epichlorohydrin rubber (CO, ECO), butyl rubber (IIR), halogenated butyl rubber (X-IIR), acrylic rubber (ACM), rubber obtained by bromination of a copolymer of isobutylene and p-methylstyrene (BIMS), fluororubber (FKM) and silicone rubber (Q).

  A thermoplastic elastomer may be used independently or may be used by blending arbitrary 2 or more types.

  The thermoplastic elastomer may be used by blending a thermoplastic resin. The thermoplastic resin to be blended may be the same type of resin as the resin contained in the thermoplastic elastomer as a hard segment component or a different type of resin.

  Among these thermoplastic elastomers, an olefinic thermoplastic elastomer in which the hard segment is a polypropylene resin and the soft segment is a crosslinked rubber (EPDM) made of a terpolymer of ethylene, propylene and a diene component is preferable.

  That is, when a polypropylene resin is used for the hard segment, there are advantages in that fluidity and compatibilizing ability are excellent and appropriate scratch resistance can be imparted. Moreover, when EPDM is used for the soft segment, compatibility with polypropylene is good, and an elastic layer satisfying the formula (1) can be easily created. Further, EPDM, which is a soft segment, is preferably a crosslinked rubber because rubber elasticity is easily obtained.

  Further, when the ratio of the EPDM cross-linked rubber, which is a soft segment, is large, rubber elasticity is easily obtained, but the fluidity required as a thermoplastic elastomer may be low. For example, by making the dispersed state of the crosslinked rubber of EPDM, which is a soft segment, into a hard resin, which is a hard segment, with a smaller particle size, it becomes easier to achieve both rubber elasticity and fluidity. Can think. Examples of the olefin-based thermoplastic elastomer whose hard segment is a polypropylene resin and soft segment is a crosslinked rubber of EPDM and can easily create an elastic layer satisfying the above formula (1) include the following. EXELINK 1101N, 1200N, 1300N, 1400N, 1500N, 1600N, 1700N, 1800N, 1101B, 1200B, 1300B, 1400B, 1500B, 1600B, 1700B, 1800B (all trade names, manufactured by JSR Corporation).

  Moreover, various additives can be blended with these thermoplastic elastomers as necessary to form an elastic layer. Additives include components necessary for the functions required for the elastic layer itself, conductive agents, non-conductive fillers, softeners, etc., and thermoplastic elastomer molded bodies, depending on the specific application of the developing roller. Various additive components, dispersion accelerators and the like that are used in the process are used. These addition amounts can also be selected according to the characteristics required for the intended application.

  Examples of the conductive agent added to the elastic layer include an ionic conductive agent based on an ionic conductive mechanism and an electronic conductive conductive agent based on an electronic conductive mechanism. Either one of them may be used in combination.

Examples of the ion conductive conductive agent include the following. LiCF ₃ SO ₃ , NaClO ₄ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , NaSCN, KSCN, salts of Group 1 metals such as NaCl; ammonium such as NH ₄ Cl, NH ₄ SO ₄ , NH ₄ NO ₃ Salts; salts of Group 2 metals of the periodic table such as Ca (ClO ₄ ) ₂ and Ba (ClO ₄ ) ₂ ; these salts and 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, etc. Complexes of these with polyhydric alcohols and their derivatives; complexes of these salts with monools such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether; quaternary ammonium salts Cationic surfactants such as fats Anionic surfactants such as aromatic sulfonates, alkyl sulfates, and alkyl phosphates; amphoteric surfactants such as betaines. These ion conductive materials are powdery or fibrous and can be used alone or in admixture of two or more.

  Moreover, the following are mentioned as an electroconductive electrically conductive agent. Metal powders and metal fibers of aluminum, palladium, iron, copper, silver; carbon black; powders of metal oxides and metal compounds; the surface of resin particles and inorganic particles made conductive; carbon nanotubes and carbon fiber powder Carbon-based conductive agent such as

  Among these, carbon black is suitable because it can be obtained relatively easily and good chargeability can be obtained regardless of the type of the main component thermoplastic elastomer.

  When carbon black is used as a means for making the elastic layer conductive, carbon black having a DBP absorption of 50 ml / 100 g or more and 100 ml / 100 g or less is preferable. When carbon black having a DBP absorption in this range is used, the hardness of the elastic layer can be kept relatively low, and aggregation of the carbon black due to the shearing force is less likely to occur. Since there is almost no change, it becomes easy to obtain desired conductivity.

  Carbon black having a DBP absorption of 50 ml / 100 g or more can be easily dispersed in the elastic body layer, and the amount added for providing conductivity can be suppressed. Carbon black having a DBP absorption amount of 100 ml / 100 g or less has a large reinforcing effect on the elastic layer, and it becomes easy to obtain a desired conductivity stably by adding a small amount to a suitable hardness. More preferably, the carbon black has a DBP absorption in the range of 60 ml / 100 g to 90 ml / 100 g.

  The DBP absorption amount of carbon black indicates the DBP absorption amount per 100 g of carbon black, and is one of the indexes for determining the size of the structure of carbon black. The DBP absorption is measured in accordance with JIS K6217-4 (2001) “Carbon black for rubber—Basic characteristics—Part 4: Determination of DBP absorption”.

  As a method for extracting and isolating the carbon black component from the elastic layer, a generally known method may be used. For example, the elastic layer 12 is cut out from the developing roller 1 and the elastic layer piece, which has been reduced to about 1 mm to 2 mm square, is heated in a rotary kiln under a nitrogen stream at a high temperature for a certain period of time to decompose the rubber component. The carbon black component is recovered from the residue. The temperature and time may be selected according to the type and amount of rubber contained in the elastic layer, and the rubber is decomposed into hydrocarbons and / or oil. The recovered residue may contain inorganic component powders such as silica, quartz, and talc in addition to the carbon black component, but these can be easily separated from the difference in specific gravity.

  The carbon black used in the present invention may be a commercially available product, a product obtained by treating a commercially available product, or a newly produced product, and is not particularly limited. Oil furnace black, gas furnace black, channel type carbon black, those obtained by oxidizing these carbon blacks, and the like can be used.

  The amount of carbon black added is usually preferably 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of rubber forming the elastic layer. If it is 10 parts by mass or more, it becomes easy to stably obtain desired conductivity, and if it is 80 parts by mass or less, the hardness does not become too high. Furthermore, it is more preferably 20 parts by mass or more and 50 parts by mass or less from the viewpoint that dispersion into the elastic layer is easy and conductivity can be obtained stably.

  Examples of the softener added to the elastic layer include oil and plasticizer. As the oil, paraffinic, naphthenic, aromatic mineral oils, synthetic oils known per se made of hydrocarbon oligomers, process oils, and the like can be used. The synthetic oil is preferably an oligomer with an α-olefin, an oligomer of butene, or an amorphous oligomer of ethylene and an α-olefin. As the plasticizer, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl separate (DOS), dioctyl adipate (DOA) and the like can be used.

  Of these, paraffinic oils are preferred, and those that do not contain aromatic organic compounds are preferred. If an aromatic organic compound is contained in the paraffinic oil, the surface easily oozes out, and the resistance as a developing roller may be changed, or the surface may be deteriorated by moving to the surface of the coating layer. Examples of paraffinic oils that do not contain aromatic organic compounds include Diana Process Oil PW-90 and Diana Process Oil PW-380 (both trade names, manufactured by Idemitsu Kosan Co., Ltd.).

  Nonconductive fillers that can be added to the elastic layer include diatomaceous earth, quartz powder, dry silica, wet silica, titanium oxide, zinc oxide, aluminosilicate, and calcium carbonate.

  As means for dispersing the thermoplastic resin and elastomer to be blended, the conductive agent, the non-conductive filler, the softening agent, and other various additives (processing aid, dispersion accelerator) in the thermoplastic elastomer as the main component, Conventionally used means can be used. That is, it can mix using apparatuses, such as a short screw extruder, a twin screw extruder, a kneader, a Banbury mixer, and a continuous mixer. These may be appropriately selected and used according to the type of thermoplastic elastomer or conductive agent as the main component. Among them, a twin screw extruder is preferably used because it is excellent in mixing performance of the apparatus itself and can reduce contamination by foreign matters during mixing.

The elastic body layer 12 has a temperature (° C.) at which the viscosity of the elastic body layer becomes 5.0 × 10 ³ Pa · s after repeating the measurement using the flow tester at the temperature of T1 (H) five times. It is preferable that T5 (L) and T1 (L) satisfy the relationship of the following formula (2).
−12 ° C. ≦ T5 (L) −T1 (L) ≦ 2 ° C. Formula (2)

  If {T5 (L) -T1 (L)} is 2 ° C. or less, it is possible to suppress a relatively high change in viscosity during molding, and there is little change in flow characteristics and the dimensional accuracy of the elastic layer is improved. it can. Further, when {T5 (L) -T1 (L)} is −12 ° C. or higher, a change due to repeated shearing history is small, and stable dimensional accuracy can be obtained even when kneading lots are different. Furthermore, the material of the elastic layer whose {T5 (L) -T1 (L)} is −12 ° C. or higher and 2 ° C. or lower is used under the same manufacturing conditions when it is melted and reused after being used as a developing roller. Can be used.

The main factor that changes T5 (L) relative to T1 (L) is that the polymer chain of the thermoplastic elastomer itself is broken by shear. As the molecular weight decreases, the temperature at which the viscosity becomes 5.0 × 10 ³ Pa · s decreases. In the composition used for the elastic layer, changes in the dispersion state of carbon black, cohesion, and the interaction between the polymer chain and carbon black also affect the value of T5 (L), and the viscosity is The temperature that becomes 5.0 × 10 ³ Pa · s may change in a higher direction.

<Measurement of T5 (L)>
Here, the measurement of T5 (L) is performed as follows.

The elastic body layer portion was cut out from the developing roller and cut into a rectangular parallelepiped shape of about 2 mm square to make a sample. The flow tester CFT-500D (trade name) is set to the constant temperature method under the following conditions, and the flow tester CFT-500D is allowed to flow out from the hole at the center of the sample stage at T1 (H) obtained separately.
Die hole diameter: 0.5mm
Die length: 1.0 mm
Cylinder pressure: 4.903 × 10 ⁵ (Pa)
Measurement mode: Constant temperature method Preheating time: 600 seconds Temperature: T1 (H) [° C]

  The strand-shaped material that has flowed out is naturally cooled to 30 ° C. or lower, and then placed in an environment of normal temperature and humidity (23 ° C., 55% RH) for 2 hours or longer. A sample obtained by cutting the strand-shaped material into a length of 3 mm to 5 mm is used as a sample, and the sample is allowed to flow out from the hole at the center of the sample stage of the flow tester under the above conditions. Repeat this operation four times.

As described above, by performing the measurement by the constant temperature method five times at a temperature of T1 (H), a sample that has repeatedly flowed out is obtained as “the elastic body layer cut out from the developing roller is brought to a temperature of T1 (H). The measurement using a flow tester is repeated for 5 times, and the elastic layer material is referred to. Using this as a sample, the outflow amount is measured under the following conditions using a flow tester CFT-500D (trade name).
Die hole diameter: 0.5mm
Die length: 1.0 mm
Cylinder pressure: 4.903 × 10 ⁵ (Pa)
Measurement mode: Temperature rising method Preheating time: 300 seconds Temperature rising rate: 3.0 ° C / min
Temperature range: 50 ° C to 300 ° C

A temperature-viscosity curve is prepared in the same manner as in the measurement of T1 (L) and T1 (H), and the temperature (° C.) at which the viscosity becomes 5.0 × 10 ³ Pa · s from the prepared temperature-viscosity curve. : Determine T5 (L).

  The thickness of the elastic layer can be variously changed depending on the purpose of use of the developing roller, but is preferably 0 in order to ensure a uniform nip width when contacting the photosensitive drum and satisfy a suitable set recoverability. 0.5 mm or more, more preferably 1.0 mm or more. The thickness of the elastic layer is not particularly limited as long as the outer diameter accuracy of the developing roller to be manufactured is not impaired, but in general, if the thickness of the elastic layer is excessively increased, the manufacturing cost is within an appropriate range. It is difficult to suppress, and it becomes difficult to stabilize the dimensional accuracy of the developing roller itself. Considering these practical restrictions, the thickness of the elastic layer is preferably 5.0 mm or less, and more preferably 4.0 mm or less. Accordingly, the thickness of the elastic layer is preferably in the range of 0.5 mm to 5.0 mm, and more preferably in the range of 1.0 mm to 4.0 mm. Note that the thickness of the elastic layer is appropriately determined according to the hardness thereof.

  As a method for forming the elastic body layer, conventionally used means, extrusion molding methods, and injection molding methods can be used. However, in the present invention, since a mold is used, the dimensional accuracy of the outer diameter and uniform surface properties are achieved. It is preferable to adopt injection molding from the point that it is easy to obtain.

  The developing roller manufacturing method for developing the electrostatic latent image by supplying the toner to the surface of the latent image carrier on which the electrostatic latent image is formed by carrying the toner of the present invention is an elastic material including a thermoplastic elastomer. The elastic body layer is formed by injection molding the raw material composition for the body layer on the outer peripheral surface of the shaft core body. As the production method, first, a raw material composition for an elastic layer containing a thermoplastic elastomer having the following viscosity-temperature characteristics is prepared.

The temperature at which the viscosity becomes 5.0 × 10 ³ Pa · s (° C.): T0 (L) and the temperature at which the viscosity becomes 5.0 × 10 ⁴ Pa · s (° C.): T0 (H) is the following formula (3 ) And T0 (H) is 115 ° C. or higher and 150 ° C. or lower.
5 ° C. ≦ T0 (L) −T0 (H) ≦ 18 ° C. Formula (3)

  When {T0 (L) -T0 (H)} is in the above range, it is easy to produce a developing roller with good roller dimensional accuracy and surface quality, and uniform resistance and hardness as a roller at low cost. can do.

<Measurement of T0 (L) and T0 (H)>
For T0 (L) and T0 (H), the raw material composition is mixed with a twin screw extruder, extruded in a strand shape, and cut into pellets (size is approximately 5 mm square or less). , T1 (l) and T1 (H) were measured in the same manner as above, and obtained from a temperature-viscosity curve. The temperature (° C.) at which the viscosity is 5.0 × 10 ³ Pa · s is T0 (L), and the temperature (° C.) at which the viscosity is 5.0 × 10 ⁴ Pa · s is T0 (H). It is.

  The developing roller of the present invention may be used with the elastic body layer 12 provided. The surface of the elastic body layer 12 is treated or a coating layer (surface layer) 13 is provided on the outer peripheral surface of the elastic body layer 12. You may use it.

  In the present invention, the hardness of the surface of the developing roller is preferably 50 degrees or more and 80 degrees or less (Asker-C hardness) regardless of whether or not the coating layer 13 is formed.

  When the surface of the developing roller is in this range, it is flexible and easily deformed, and an appropriate nip width can be obtained in the case of contact development. When the hardness is 50 degrees or more, it is easy to obtain a developing roller having sufficient deformation recovery properties. When the hardness is 80 degrees or less, the followability to the blade is sufficient and it is easy to coat the toner uniformly. At the same time, an appropriate nip width can be obtained in the case of contact development. The hardness of the developing roller surface is more preferably in the range of 50 to 65 degrees (Asker-C hardness).

<Measurement of roller hardness (Asker-C hardness)>
The Asker-C hardness in the present invention is the hardness of the developing roller surface measured using an Asker C-type spring rubber hardness meter (trade name, manufactured by Kobunshi Keiki Co., Ltd.) in accordance with the Japan Rubber Association standard SRIS0101. is there. A hardness meter is brought into contact with a developing roller placed in an environment of a temperature of 25 ° C. and a relative humidity of 50% RH for 12 hours or more with a force of 10 N, and the value measured 30 seconds later is defined as the hardness of the measurement location. The measurement was performed at 9 locations, 3 locations that were divided into 4 parts in the longitudinal direction of the developing roller and 3 locations divided by 120 ° in the circumferential direction, and the value obtained by arithmetically averaging the obtained measured values The hardness of the roller. For the hardness (Asker-C hardness), a value measured with the developing roller shape as it is is used. If the material of the elastic layer of the developing roller is the same but the layer thickness is different, the hardness will be different. In other words, when the thickness of the elastic layer is thin, it is easily affected by the shaft core, but it can be regarded as a numerical value reflecting the actual use state of the developing roller.

When the coating layer 13 is formed, the components thereof are not particularly limited, and examples thereof include the following. Cross-linked resins such as polyamide resin, urethane resin, urea resin, epoxy resin and acrylic resin; thermoplastic resins such as fluororesin, thermoplastic polyimide, polyamide, polyethylene, polypropylene and polystyrene; silica-based materials such as SiO ₂ and SiOx; Diamond-like carbon (may be referred to as DLC). These materials may be used alone or in admixture of two or more.

SiO ₂ is composed of an oxygen-silicon-oxygen skeleton. SiOx is a silicon oxide-based material having a structure having an oxygen-silicon-oxygen main skeleton and a silicon-carbon bond. DLC is a general term for carbon thin films with high hardness, electrical insulation, and infrared transparency similar to diamond. It contains carbon as the main component, contains a small amount of hydrogen, diamond (SP ³ ) bonds, and graphite (SP ² ). It is a material with an amorphous structure in which both bonds are mixed.

  The coating layer 13 is formed by a method of coating the coating material on the elastic layer surface (wet method) or a method of depositing a coating layer material on the elastic layer surface (physical vapor deposition (PVD) method or chemical vapor deposition method). (CVD) method) is formed on elastic body layer 12. In addition, there are methods such as dip coating, spray coating, and roll coating as wet methods, methods such as vacuum deposition, sputtering, and ion plating in PVD methods, and plasma CVD, thermal CVD, and laser CVD in CVD methods. The following methods can be exemplified.

  Among these, since it is advantageous to maintain the dimensional accuracy of the elastic body layer 12, a method that does not require heat curing when forming the coating layer is preferable. In addition, the coating layer is preferably formed by a dry method because it is advantageous for maintaining the surface property of the elastic body layer 12. For example, in the plasma CVD method, an apparatus whose schematic diagram is shown in FIG. 5 is used.

  In FIG. 5, reference numeral 48 denotes a roller (raw material roller) on which an elastic layer on which a coating layer is formed. The raw material roller 48 is placed between the flat plate electrodes 43 in the vacuum chamber 47, and is rotated by a rotating device 46. It has been rotated. The vacuum chamber 47 is decompressed by a decompression device 45 such as a vacuum pump, and the raw material for the coating layer is introduced from the reaction gas supply unit 41 and the dilution gas is introduced from the dilution gas supply unit 42. Depending on the type of coating layer, the coating layer gas is silane or alkylsilane, and argon or nitrogen is appropriately selected as the dilution gas. When the introduced source gas reaches a predetermined pressure and flow rate in the vacuum chamber, power is supplied from the high frequency power supply 44 and plasma processing is performed until a predetermined film is formed. Thereafter, the power supply 44 is shut off, nitrogen or air is introduced into the vacuum chamber, and when the pressure becomes normal, the developing roller on which the coating layer is formed is taken out.

  Depending on the type of material used for the elastic layer, before forming the coating layer 13, the outer peripheral surface of the elastic layer is modified by a known method such as corona treatment, plasma treatment, low-pressure mercury UV treatment, or excimer UV treatment. You may quality.

  The layer structure on the outer peripheral surface of the shaft core in the developing roller according to the present invention may be that at least one elastic layer is formed, but the elastic layer may be two or more layers, In the case of having a coating layer, two or more layers may be provided for each function.

  As described above, the developing roller of the present invention is a developing roller having excellent roller dimensional accuracy and surface property, uniform resistance and hardness as a roller, and excellent productivity. Because of this advantage, when used as a developing roller in a process cartridge or an image forming apparatus, there are no vertical streaks or unevenness in image density due to pressure unevenness with the regulating member, and good images can be obtained continuously over time. Further, the above-described advantage becomes more remarkable under the condition that the image forming apparatus used is increased in speed and the process speed, that is, the speed of the photosensitive drum surface is increased. Further, the elastic layer can be melted and recovered after use of the developing roller, and can be reused as a part or all of the raw material composition of the elastic layer of the next developing roller.

  In this case, in the production of the developing roller, the raw material composition for the elastic layer can contain 30% by mass or more and 100% by mass or less of the elastic layer recovered from the used developing roller. The amount of this reuse may be less than 30% by mass, but is suitably 30% by mass or more in view of miscibility with new raw materials.

  The process cartridge of the present invention includes a latent image carrier, a charging device that uniformly charges the surface of the latent image carrier, and a developing device that develops the electrostatic latent image formed on the latent image carrier. I have. The developing device includes a developing roller that carries toner while facing the latent image carrier, and a regulating blade that regulates the layer thickness of the toner while frictionally charging the toner carried on the developing roller. The developing roller applies toner to the latent image carrier to visualize the electrostatic latent image formed on the latent image carrier as a toner image. Here, the developing roller is the developing roller of the present invention.

  The image forming apparatus of the present invention also includes a latent image carrier on which an electrostatic latent image is formed by electrophotography, and a charge for charging the latent image carrier with a charge amount necessary for forming the electrostatic latent image. And an electrostatic latent image forming device for forming an electrostatic latent image on a charged region of the latent image carrier. Furthermore, the book image forming apparatus is a developing device for attaching toner to the electrostatic latent image formed by the electrostatic latent image forming apparatus and visualizing it as a toner image, and transferring the toner image to transfer paper A transfer device. The image forming apparatus of the present invention is characterized in that the developing roller for carrying toner in a state facing the latent image carrier in the developing device is the developing roller of the present invention.

  FIG. 3 is a schematic cross-sectional view of an example of a tandem type color image forming apparatus having image forming portions for each color of black, magenta, cyan, and yellow. Each image forming unit has the same basics although there are slight differences in specifications depending on colors.

  The image forming apparatus shown in FIG. 1 is a photosensitive drum 21 as a latent image carrier on which an electrostatic latent image is formed by an electrophotographic method, and charges the latent image carrier with a charge amount necessary for forming the electrostatic latent image. A charging member 26 is provided as a charging device. In addition, an electrostatic latent image forming device (not shown) for forming an electrostatic latent image on a charged region of the latent image carrier, and a toner image attached to the electrostatic latent image to form a toner image. The developing device 2 is provided. Further, a transfer device having a transfer roller 31 is provided to transfer the toner image formed on the photosensitive drum 21 onto the transfer paper. The image forming apparatus includes the developing roller of the present invention as the developing roller 1 of the developing device 2.

  The photosensitive drum 21 rotates in the direction of the arrow, is uniformly charged by a charging member 26 for charging, and is a laser beam that is an exposure unit of an electrostatic latent image forming apparatus for writing an electrostatic latent image on the photosensitive drum 21. 25, an electrostatic latent image is formed on the surface of the photosensitive drum 21. The electrostatic latent image formed by the laser beam 25 is developed by applying toner by the developing device 2 disposed in contact with the photosensitive drum 21, and is visualized as a toner image. Development is performed by so-called reversal development in which a toner image is formed on the exposed portion. The visualized toner image on the photosensitive drum 21 is transferred by a transfer roller 31 that is a transfer member to a transfer sheet 36 that is a recording medium that is sent on the conveyance belt 34 in synchronization with the movement of the developer image. . In the drawing, the toner images formed by the image forming unit are sequentially stacked on the transfer paper 36. The transfer paper 36 onto which the toner image has been transferred in the last image forming section is further transported by the transport belt 22 and sent to the fixing device 29 where it is fixed, discharged outside the device, and a series of printing operations is completed. To do.

  On the other hand, untransferred toner remaining on the photosensitive drum 21 without being transferred is scraped off by a cleaning blade 28 as a cleaning member for cleaning the surface of the photosensitive drum 21 and stored in a waste toner container 27. The cleaned photosensitive drum 21 is again subjected to a charging process and repeatedly used for image formation.

  The developing device 2 includes a developing roller 1 that carries toner while facing the photosensitive drum 21, a toner application member 22 that supplies toner to the developing roller 1, and a toner carried on the developing roller 1 while frictionally charging the toner. And a regulating blade 24 for regulating the toner layer thickness. In the developing device 2, the developing roller 1 applies the toner 23 to the photosensitive drum 21 which is a latent image carrier, thereby visualizing the electrostatic latent image as a toner image, thereby forming a toner image. The developing device 2 includes a developing container containing a non-magnetic toner 23 as a one-component toner, and a developing roller 1 that is a toner carrier positioned in an opening extending in the longitudinal direction in the developing container. It has a roller. Further, the regulating blade 24 is disposed along the upper edge of the opening extending in the longitudinal direction. As the structure of the toner application member 22, a foamed skeleton-like sponge structure or a fur brush structure in which fibers such as rayon and polyamide are planted on the shaft core is used for supplying toner to the developing roller 1 and stripping off undeveloped toner. From the point of view, it is preferable. For example, an elastic roller having a diameter of 16 mm in which polyurethane foam is provided on the shaft core can be used. The contact width of the toner applying member 22 with respect to the developing roller 1 is preferably 1 mm or more and 8 mm or less, and the developing roller 1 is preferably given a relative speed at the contact portion.

  The conveyor belt 34 is wound around the driving roller 30, the tension roller 33, and the driven roller 36. When the transfer paper 36 is fed by the pair of paper feed rollers 37, the transfer paper 36 is attracted to the transport belt 34 by the action of the driven roller 36 and the suction roller 38 facing it, and the transport belt 34 is moved accordingly. The transfer paper 36 also moves.

  The image forming unit of this apparatus is formed between a driven roller 36 and a driving roller 30, and a transfer roller 31 is provided with a conveyance belt 34 interposed therebetween. Reference numeral 32 denotes a bias power source for transfer.

  In this apparatus, the photosensitive drum 21, the charging device 26, the developing device 2, the cleaning blade 28, and at least one cleaning member including the waste developer container 27 are combined to be detached from the main body as an electrophotographic process cartridge. It can also be possible. A schematic sectional view of an example of the electrophotographic process cartridge is shown in FIG. In this figure, members having the same functions as in the above description are given the same reference numerals.

  Hereinafter, the present invention will be described more specifically with reference to examples. Here, a developing roller having an elastic body layer and a coating layer on the outer peripheral surface of the shaft core as described above will be described as an example. These examples are examples of the best mode of the present invention, but the present invention is not limited to the examples. The developing roller manufactured by the method shown in the embodiment can be suitably used as a developing roller used in an electrophotographic apparatus in its application.

  The following materials were used as raw materials for forming the elastic layer.

(Thermoplastic elastomer)
-Thermoplastic elastomer A: "Exelin 1101N" (trade name, manufactured by JSR Corporation).
-Thermoplastic elastomer B: "Exelinck 1200N" (trade name, manufactured by JSR Corporation).
-Thermoplastic elastomer C: "Exelin 1300N" (trade name, manufactured by JSR Corporation).
-Thermoplastic elastomer D: "EXCELINC 1400N" (trade name, manufactured by JSR Corporation).
Thermoplastic elastomer E: “Santoprene 8211-25” (trade name, manufactured by AES Co., Ltd.).
The thermoplastic elastomers A, B, C, D and E are all materials containing a polypropylene resin and a crosslinked rubber made of an ethylene, propylene and diene copolymer. In general, when commercially available, it may be classified as a dynamically crosslinked olefinic thermoplastic elastomer.
-Thermoplastic elastomer F: "Excelink 3300N" (trade name, manufactured by JSR Corporation).
The thermoplastic elastomer F is a material containing a polypropylene resin and rubber (not cross-linked) made of ethylene, propylene and a diene copolymer. In general, when commercially available, it may be classified as a crystalline pseudo-crosslinked olefin-based thermoplastic elastomer.

(Carbon black)
Carbon black A: “Toka Black # 7360SB” (trade name, manufactured by Tokai Carbon Co., Ltd .: DBP absorption amount = 87 ml / 100 g).
Carbon black B: “Toka Black # 8300” (trade name, manufactured by Tokai Carbon Co., Ltd .: DBP absorption amount = 76 ml / 100 g).
Carbon black C: “Printex35” (trade name, manufactured by Evonik Degussa Japan Co., Ltd .: DBP absorption amount = 42 ml / 100 g).
Carbon black D: “Toka Black # 7550” (trade name, manufactured by Tokai Carbon Co., Ltd .: DBP absorption amount = 53 ml / 100 g).
Carbon black E: “Toka black # 7350” (trade name, manufactured by Tokai Carbon Co., Ltd .: DBP absorption amount = 100 ml / 100 g).
Carbon black F: “Mitsubishi Carbon Black MA230” (trade name, manufactured by Mitsubishi Chemical Corporation: DBP absorption amount = 113 ml / 100 g).

(Other)
Process oil: “Diana Process Oil PW-90” (trade name, manufactured by Idemitsu Kosan Co., Ltd.).

[Example 1] (Manufacture of developing roller 1)
100 parts by weight of thermoplastic elastomer A and 20 parts by weight of carbon black A are kneaded with a twin screw extruder “TEM-26SS” (trade name, manufactured by Toshiba Machine Co., Ltd.) Raw material composition pellets were prepared. The twin screw extruder has a screw diameter of D30 mm, a length of L960 mm, and an L / D32.

  An adhesive (primer) “Chemlock 459X” (trade name, manufactured by Rhode Co., Ltd.) was applied to the outer peripheral surface of a nickel-plated SUS metal core (diameter 6.0 mm) as a shaft core body, and dried. .

  Prepared a mold for injection molding that has a cylindrical pipe with an inner diameter (diameter) of 12.4 mm and a length of 240 mm, and is provided with gates at two points 180 ° apart from the center of the circle on one end face of the cylinder. did. The shaft core was placed at the center of the cylindrical pipe of the mold, and the mold temperature was adjusted to 35 ° C. It was set in an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd.), the raw material composition was heated and melted, and injection molded from the nozzle of the injection molding machine into the mold through the two gates. After cooling, it was removed from the mold, and an elastic body layer having a diameter of 12.0 mm and a thickness of 3.0 mm was formed on the outer peripheral surface of the shaft core body. The cylinder temperature of the injection molding machine was appropriately adjusted in the range of 160 ° C. to 200 ° C. in accordance with the flow characteristics of the thermoplastic elastomer.

  Furthermore, the roller which has the elastic body layer which consists of a composition containing a thermoplastic elastomer was obtained by cut | disconnecting and removing the excess elastic body layer of both ends, and making the length of an elastic body layer into 232 mm.

While the roller having the elastic layer obtained above is installed in the plasma CVD apparatus shown in FIG. 5 and rotated at 20 rpm, a raw material gas is supplied to form a coating layer on the outer peripheral surface of the elastic layer. A developing roller 1 was obtained. The raw material gas was a mixed gas of hexamethyldisiloxane 1.5 sccm, oxygen 0.5 sccm, and argon 22.5 sccm. Here, “sccm” represents a volume flow rate of 1 cm ³ per minute when the source gas is at 0 ° C. and 1 atm. Further, the pressure in the vacuum chamber was set to 25.3 Pa, high frequency heat treatment was performed at a frequency of 13.56 MHz and an output of 120 w for 4 minutes to form a coating layer. Hexamethyldisiloxane was a primary product with a purity of 99%, oxygen with a purity of 99.999% or more, and argon gas with a purity of 99.999% or more.

[Examples 2 and 3] Manufacture of developing rollers 2 and 3 The developing roller was the same as Example 1 except that the amount of carbon black used was 30 parts by mass (Example 2) or 40 parts by mass (Example 3). 2 or 3 was obtained.

[Examples 4 and 5] Production of developing rollers 4 and 5 As carbon black, carbon black B was used in the same manner as in Example 1 except that 10 parts by mass (Example 4) or 20 parts by mass (Example 5) was used. A developing roller 4 or 5 was obtained.

[Examples 6 and 7] Production of developing roller 6 or 7 The thermoplastic elastomer B (Example 6) or the thermoplastic elastomer C (Example 7) is used as the thermoplastic elastomer, and the amount of carbon black A added is 30. A developing roller 6 or 7 was obtained in the same manner as in Example 1 except that the amount was increased to part by mass.

[Examples 8 to 11] Production of developing rollers 8 to 11 Furthermore, 10 parts by mass (Example 8), 20 parts by mass (Example 9), 40 parts by mass (Example 10) or 60 parts by mass of process oil ( Example 11) A developing roller 8, 9, 10 or 11 was obtained in the same manner as in Example 1 except that it was added.

[Examples 12 to 15] Production of developing rollers 12 to 15 As carbon black, carbon black C (Example 12), D (Example 13), E (Example 14) or F (Example 15) was used. The development roller 12, 13, 14 or 15 was obtained in the same manner as in Example 1 except that the amount used was increased to 30 parts by mass.

[Example 16] Production of developing roller 16 The developing roller 16 was changed in the same manner as in Example 1 except that the thermoplastic elastomer A was changed to the thermoplastic elastomer D and the amount of carbon black A added was increased to 30 parts by mass. Produced.

[Comparative Examples 1 to 3] Production of developing rollers 17 to 19 As the thermoplastic elastomer, 10 parts by mass (Comparative Example 1), 20 parts by mass (Comparative Example 2) or 30 parts by mass (Comparative Example 3) of thermoplastic elastomer E are used. A developing roller 17, 18 or 19 was obtained in the same manner as in Example 1 except that was used.

[Comparative Example 4] Production of developing roller 20 Developing roller 20 was obtained in the same manner as in Example 1 except that carbon black A was used in an amount of 10 parts by mass, and 120 parts by mass of process oil was added.

[Comparative Example 5] Production of developing roller 21 The developing roller 21 was prepared in the same manner as in Example 1 except that 100 parts by weight of the thermoplastic elastomer F was used as the thermoplastic elastomer and 10 parts by weight of carbon black B was used as the carbon black. Obtained.

  Table 1 shows raw materials for forming the elastic layer used for the developed developing rollers 1 to 21.

  The values of T1 (L), T1 (H), T5 (L) of the elastic layer of the developed developing rollers 1 to 21, {T1 (L) -T1 (H)} (difference 1), {T5 (L ) -T1 (L)} (difference 2) and the hardness of the developing roller surface (Asker-C hardness) are shown in Table 2.

  The characteristics of the produced developing rollers 1 to 21 were evaluated as follows.

<Dimensional accuracy>
Outer diameter measured at every 1 ° on each side of the cut surface (total of 10 locations) with the axial length of the elastic layer divided into 9 parts, excluding 5% of each length in the axial direction of the elastic layer. Judgment was made based on the difference between the average maximum and minimum values. The outer diameter was measured every 1 ° by rotating the laser measuring machine in the circumferential direction, and the total 180 measured values were arithmetically averaged to obtain the average outer diameter value at that point. Note that the same mold is used for injection molding. Regarding the examples and comparative examples, 10 developing rollers were measured, and the outer diameters of the developing rollers of the examples and comparative examples were evaluated by the arithmetic average as follows. The developing roller to be measured was measured after being left for 24 hours or more in an environment of a temperature of 25 ° C. and a relative humidity of 50% RH.
A: The difference between the maximum value and the minimum value is 50 μm or less.
B: The difference between the maximum value and the minimum value is more than 50 μm and not more than 100 μm.
C: The difference between the maximum value and the minimum value is more than 100 μm and 150 μm or less.
D: The difference between the maximum value and the minimum value is more than 150 μm.

<Surface property>
The surface of the produced developing roller was visually observed and evaluated according to the following criteria. A: The surface of the developing roller is clean and glossy like a mirror surface.
B: The surface of the developing roller is smooth but not glossy, and there are portions where the colors look different.
C: There is a portion where the color looks different on the entire surface of the developing roller.
D: There are clear irregularities on the surface of the developing roller.

<Image evaluation>
A color laser beam printer “Satera LBP5400” (trade name, manufactured by Canon Inc.) was prepared as an image forming apparatus. This color laser beam printer is a tandem type printer having four color cartridges, each having an image writing means (laser beam), and a transfer belt. The standard image creation capability is 21 sheets / minute for A4 size.

  The color cartridge includes a photosensitive drum, a charging unit, a developing unit, and a cleaning unit. The charging means is a charging roller. Further, the developing means is provided with a developing roller at the opening of the toner container, supplies toner onto the developing roller in contact with the developing roller, and frictionally charges the toner to scrape the return toner that has not been used for toner image formation. A toner supply roller as an application member is provided. Further, the developing means is provided with a regulating blade for making the amount of toner carried on the developing roller constant and applying frictional charging in contact with the developing roller (corresponding to the one-component contact developing system). The developing roller is in contact with the photosensitive drum. The cleaning means is composed of a cleaning blade and a collected toner container, which are cleaning members that are in contact with the photosensitive drum and wipe off residual toner and transfer material waste on the photosensitive drum. Further, pre-exposure means for removing the charge remaining on the photosensitive drum before charging by the charging roller is provided.

  Installed as a developing roller a cyan color cartridge that incorporates the developing rollers 1 to 23 produced in the examples and comparative examples as LBP5400 (product name), which has been modified to increase the output speed to 25 sheets of A4 paper / min. did. The remaining magenta, yellow, and black color cartridges were placed at the respective stations, with the toner removed and the remaining toner detection mechanism disabled.

Using the LBP5400 (trade name) remodeled as described above, the printed image of the standard chart shown in FIG. 6 (LETTER size, solid black 6 places, S letter placed, print ratio 4%), entire surface The solid image and the entire halftone image were continuously output in the following order. Note that LETTER size plain paper “XEROX 4024 paper” (trade name) was used as the transfer material.
Standard chart: From 1st sheet to 10th sheet.
Full solid image: 11th sheet.
Full halftone image: 12th sheet.
Standard chart: From the 13th sheet to the 750th sheet.
Full solid image: 751st sheet.
Full halftone image: 752nd image.

(Initial concentration)
Five solid black areas printed solid on the standard chart (output on the second sheet) are measured with a reflection densitometer “RD918” (trade name, manufactured by Macbeth), and the average value of the five points is the image of the sample. The concentration was evaluated as follows.
A: The average value is 1.20 or more.
B: The average value is 1.15 or more and less than 1.20.
C: Average value of 1.10 or more and less than 1.15.
D: The average value is less than 1.10.

(Vertical stripes in the initial image)
Vertical stripes appearing in a solid image (output on the 11th sheet) and a halftone image (output on the 12th sheet) in which the entire image area is uniform were observed and evaluated according to the following criteria. The vertical streak means that unevenness in the width of about 5 mm to 20 mm in the vertical direction is connected in a streak shape and is considered to be due to pressure unevenness with the regulating member.
A: Vertical stripes are not confirmed in both solid images and halftone images.
B: Vertical streaks are observed in the solid image, and there are no more than two portions in the horizontal direction that are light (low density), and no vertical streak is confirmed in the halftone image.
C: Vertical stripes are seen in the halftone image, and the lightened portion (light density) is within two places in the horizontal direction.
D: Vertical stripes are seen in the halftone image, and there are three or more portions in the horizontal direction that are faint (low density).

(Shading unevenness in the initial image)
Five inspectors visually observed the shading unevenness (excluding vertical stripes) appearing in the solid image (output on the 11th image) and the halftone image (output on the 12th image) where the entire image area is uniform. The evaluation was based on the following criteria. The evaluation results were ranked, and the median value (third evaluation) was used as the evaluation of initial density unevenness on the developing roller. Here, the density unevenness is determined by evaluating what is seen in the developing roller cycle.
A: No shading unevenness is confirmed in both the solid image and the halftone image.
B: Light and shade unevenness is observed in a solid image, but is not confirmed in a halftone image.
C: Light and shade unevenness can be seen in a halftone image, but at a level with no problem.
D: Shading unevenness is seen in a halftone image, and the shading difference is conspicuous.

(Shading unevenness in images over time)
Five inspectors visually observed the shading unevenness (excluding vertical stripes) appearing in the solid image (output on the 751st sheet) and the halftone image (output on the 752nd sheet) where the entire image area is uniform. The evaluation was performed based on the same standard as the uneven density in the initial image. The evaluation results were ranked, and the median value (third evaluation) was taken as the density unevenness over time on the developing roller.

<Comprehensive evaluation>
Based on the results of the above six items (dimensional accuracy, surface property, initial density, initial vertical stripe, initial density unevenness and time-dependent density unevenness), a comprehensive evaluation was performed according to the following criteria.
A: The shading unevenness with time is A or B, and the remaining 5 items are all A.
B: Density unevenness over time is A or B, and any of the remaining five items is B.
C: Density unevenness over time is C, and the remaining 5 items are B or more.
D: Density unevenness with time is C, and any of the remaining five items is C.
E: Density unevenness over time is C, any of the remaining five items is D, or dark unevenness over time is D.

  The results of evaluation based on the above criteria are shown in Table 3.

  As shown in Table 3, Examples 1 to 16 gave good results. Among them, Examples 1 to 3, 8, and 13 were particularly good.

[Example 17] Manufacture of developing roller 22 A developing roller was prepared under the same conditions as in Example 2, incorporated as a developing roller for a cyan color cartridge, and the standard chart shown in FIG. Continuous output. Thereafter, the used developing roller 2 was collected from the cartridge. The surface of the recovery developing roller was washed with air blow, water, and dried, and then the elastic layer was cut out and pulverized into 4 mm square or less pellets by a pulverizer. This is referred to as “pellets collected from the used developing roller” (hereinafter “collected pellets”). In Example 2, the raw material composition pellet for the elastic layer produced by kneading with a twin screw extruder TEM-26SS (trade name, manufactured by Toshiba Machine Co., Ltd.) is referred to as “new pellet”.

  The developing roller 22 was produced in the same manner as in Example 2, except that the raw material composition pellet for the elastic layer was a blend of 70% by mass of new pellets and 30% by mass of recovered pellets.

[Example 18] Production of developing roller 23 The raw material composition pellets for the elastic layer were the same as in Example 2, except that a blend of 40% by mass of new pellets and 60% by mass of recovered pellets was used. A developing roller 23 was produced.

[Example 19] Production of developing roller 24 A developing roller 24 was produced in the same manner as in Example 2 except that only recovered pellets were used as raw material composition pellets for the elastic layer.

  The same evaluation as that performed on the developing rollers 1 to 21 was performed on the produced developing rollers 22 to 24. The obtained results are shown in Table 4 together with the results of Example 2.

  As shown in Table 4, Examples 17 to 19 gave good results. There was no result inferior to Example 2 in any evaluation item, and it was very good.

  The mixing ratio of the recovered pellets of the present invention is set to 30% by mass or more and 100% by mass, while the mixing ratio of the recovered pellets is less than 30% by mass, while the number of steps for performing regeneration is increased. This is because the cost merit is small and the advantage as a reproduction method cannot be obtained. Further, as described above, there is no problem in the performance of the developing roller when the collected pellets are used within this range, and it is not necessary to suppress the mixing ratio of the collected pellets in terms of performance.

  As one of the features of the present invention, by using a thermoplastic elastomer material with little change in material properties for the elastic layer of the developing roller, the thermoplastic property can be fully utilized and repeatedly utilized. is there. Note that the pellets collected from the elastic layer are not reused in the elastic layer while keeping the mixing ratio low, but the present invention is characterized in that it is used as a main material of the raw material pellet of the elastic layer. . In some cases, waste materials and non-standard materials can be mixed with new materials in a range that does not affect performance. This is different from the gist of the invention.

It is a perspective view of an example of the developing roller of the present invention. It is sectional drawing in the surface orthogonal to the axial core body of an example of the developing roller of this invention. 1 is a schematic diagram of an example of an image forming apparatus using a developing device of the present invention. It is a schematic diagram of an example of the process cartridge of the present invention. It is a figure which shows schematic structure of a CVD apparatus. It is explanatory drawing of the standard chart used for image evaluation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Developing apparatus 3 Image forming apparatus 4 Process cartridge 11 Shaft core body 12 Elastic body layer (base layer)
13 Coating layer (surface layer)
21 Latent image carrier (photosensitive drum)
22 toner application member 23 toner 24 regulating blade 25 laser light 26 charging roller 27 toner collecting container 28 cleaning member (cleaning blade)
29 Fixing Device 30 Drive Roller 31 Transfer Roller 32 Bias Power Supply 33 Tension Roller 34 Transfer Conveyor Belt 35 Followed Roller 36 Transfer Paper 37 Feeding Paper Pair 38 Adsorption Roller 41 Reactive Gas Supply Unit 42 Rare Gas Supply Unit 43 Electrode 44 High Frequency Power Supply 45 Depressurization Device 46 Rotating device 47 Vacuum chamber 48 Roller

Claims (10)

In the developing roller that carries the toner and supplies the toner to the surface of the image carrier on which the electrostatic latent image is formed, and visualizes the electrostatic latent image,
The shaft core body and at least one elastic body layer formed on the outer peripheral surface of the shaft core body,
The elastic layer contains a thermoplastic elastomer, and
Temperature (° C.) at which the viscosity becomes 5.0 × 10 ³ Pa · s when measured with an elastic body cut out from the elastic layer: T1 (L), and the viscosity becomes 5.0 × 10 ⁴ Pa · s. Temperature (° C.): A developing roller characterized in that T1 (H) satisfies the relationship of the following formula (1).
5 ° C. ≦ T1 (L) −T1 (H) ≦ 20 ° C. Formula (1)   The developing roller according to claim 1, wherein the T1 (H) is 120 ° C. or higher and 145 ° C. or lower.   The developing roller according to claim 1, wherein the developing roller has a hardness (Asker-C hardness) of 50 degrees or more and 80 degrees or less.   The developing roller according to claim 1, wherein the thermoplastic elastomer is a thermoplastic elastomer containing a polypropylene resin and a rubber made of a copolymer of ethylene, propylene and a diene component. The temperature at which the elastic body cut out from the elastic body layer has a viscosity of 5.0 × 10 ³ Pa · s after the measurement using the flow tester at the temperature of T1 (H) is repeated 5 times. (° C.) The developing roller according to claim 1, wherein T5 (L) and T1 (L) satisfy the relationship of the following formula (2).
−12 ° C. ≦ T5 (L) −T1 (L) ≦ 2 ° C. Formula (2)   The developing roller according to claim 1, wherein the elastic layer contains carbon black having a DBP absorption amount of 50 ml / 100 g or more and 100 ml / 100 g or less. A latent image carrier, a charging device that uniformly charges the surface of the latent image carrier, a developing roller that carries toner in a state of being opposed to the latent image carrier, and the toner carried on the developing roller are rubbed The charging roller is provided with a regulating member that regulates the toner layer thickness while being charged, and the developing roller applies toner to the latent image carrier to reveal the electrostatic latent image formed on the latent image carrier as a toner image. A process cartridge comprising a developing device for imaging,
7. A process cartridge, wherein the developing roller is the developing roller according to claim 1. A latent image carrier on which an electrostatic latent image is formed by electrophotography, a charging device for charging the latent image carrier with a charge amount necessary for forming the electrostatic latent image, and charging the latent image carrier An electrostatic latent image forming device for forming an electrostatic latent image in a region, a developing device for visualizing a toner image by attaching toner to the electrostatic latent image, and transferring the toner image to a transfer sheet An image forming apparatus having a transfer device,
7. The image forming apparatus according to claim 1, wherein the developing roller that bears toner in a state facing the latent image carrier in the developing device is the developing roller according to claim 1. In a method for producing a developing roller for supplying toner to the surface of a latent image carrier on which an electrostatic latent image is formed by carrying toner and developing the electrostatic latent image,
A raw material composition for an elastic body layer containing a thermoplastic elastomer having the following viscosity-temperature characteristics is prepared, and then the elastic body layer is formed by injection molding the raw material composition on the outer peripheral surface of the shaft core body. A method for producing a developing roller.
The temperature at which the viscosity becomes 5.0 × 10 ³ Pa · s (° C.): T0 (L) and the temperature at which the viscosity becomes 5.0 × 10 ⁴ Pa · s (° C.): T0 (H) is the following formula (3 ) And T0 (H) is 115 ° C. or higher and 150 ° C. or lower.
5 ° C. ≦ T0 (L) −T0 (H) ≦ 18 ° C. Formula (3)   10. The method for producing a developing roller according to claim 9, wherein the raw material composition for the elastic body layer includes 30% by mass or more and 100% by mass or less of the elastic body layer recovered from the developing roller according to claim 1. .

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