JP3584986B2 - Inspection method for toner carrier - Google Patents

Description

＊１：デグサ社製「Ｌ６」
＊２：東レ社製「ＣＭ８０００」
＊３：樹脂対比
【００４９】
表１に示した結果から明らかなように、電気抵抗に加えて、コロナ帯電から０．１秒後の表面電位の最小値により表面電荷保持能力を検査・評価してこれを適正化した実施例１，２のローラは、良好な画像を確実に形成し得ることが確認された。
【００５０】
【発明の効果】
以上説明したように、本発明の検査方法によれば、トナーを高帯電に保ち、更には白画像かぶりの発生を可及的に防止して、高速化にも耐え得る高品位な画像を確実に得ることができるトナー担持体を確実に検査することができる。
【図面の簡単な説明】
【図１】本発明トナー担持体の一例を示す概略断面図である。
【図２】トナー担持体の表面電位を測定する装置の一例を示す概略図である。
【図３】実施例，比較例で用いた計測ユニットの形状及び寸法を示す概略平面図である。
【図４】本発明画像形成装置（現像装置）の一例を示す概略断面図である。
【図５】実施例，比較例で用いた回転抵抗測定器を示す概略図である。
【符号の説明】
１ 現像ローラ
２ シャフト
３ 半導電層
３ａ 樹脂被覆層
４ トナー塗布用ローラ
５ 感光ドラム（画像形成体）
６ トナー（非磁性一成分現像剤）
７ 成層ブレード
８ 転写部
９ クリーニング部
１０ クリーニングブレード
１１ チャック
１２ コロトロン放電器（コロナ放電器）
１３ 表面電位計[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of inspecting a toner carrier used as a developing roller or the like for visualizing an electrostatic latent image with a non-magnetic one-component developer in an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus. More specifically, the present invention relates to an inspection method for surely supplying a toner carrier capable of obtaining a uniform image without white image fogging or unevenness.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, a non-magnetic one-component developer is supplied to a photosensitive drum or the like holding a latent image, and the developer is attached to the latent image on the photosensitive drum. As a development method for visualizing an image, a pressure development method is known (U.S. Pat. Nos. 3,115,2012 and 3,731,146). According to this method, a magnetic material such as a carrier is not required, so that the apparatus is simplified. It is easy to reduce the size and size, and can also handle color images because it does not contain magnetic powder.
[0003]
In this pressure development method, a developing roller (toner carrier) carrying a toner (a non-magnetic one-component developer) is brought into contact with a latent image carrier (image forming body) such as a photosensitive drum that retains an electrostatic latent image. The development is performed by causing toner to adhere to the latent image on the latent image holding member. For this reason, the developing roller needs to be formed of an elastic material having conductivity.
[0004]
That is, in the pressure development method, for example, as shown in FIG. 4, a toner application roller 4 for supplying toner and a photosensitive drum (image forming body) 5 holding an electrostatic latent image are provided. The developing roller (toner carrier) 1 is disposed on the developing roller 1. The developing roller 1, the photosensitive drum 5, and the toner coating roller 4 rotate in the directions indicated by arrows in FIG. Is supplied to the surface of the developing roller 1, and the toner is arranged in a uniform thin layer by the layering blade 7. In this state, the developing roller 1 is rotated while contacting the photosensitive drum 5 to form a thin layer. The toner adheres to the latent image on the photosensitive drum 5 from the developing roller 1 to visualize the latent image. In the drawing, reference numeral 8 denotes a transfer unit, which transfers a toner image to a recording medium such as paper. Reference numeral 9 denotes a cleaning unit, which is provided on the surface of the photosensitive drum 5 after transfer by a cleaning blade 10. The remaining toner is removed.
[0005]
In this case, the developing roller 1 must rotate while securely maintaining a state in which the developing roller 1 is in close contact with the photosensitive drum 5, and therefore, as shown in FIG. A semiconductive layer 3 made of a semiconductive elastic body obtained by dispersing carbon black or metal powder in an elastomer such as silicone rubber, NBR, EPDM, ECO, or polyurethane, or a foam body formed by foaming these is formed on the outer periphery of No. 2. It has a structure. Further, a coating layer 3a made of a resin or the like is formed for the purpose of controlling the chargeability and adhesion of the toner, controlling the frictional force between the developing roller and the layering blade, and preventing the photosensitive member from being contaminated by the elastic body of the developing roller. It may be formed on the surface.
[0006]
Further, there has been proposed a method of forming an image by directly flying toner carried on the surface of a similar toner carrying member onto paper or OHP paper via a control electrode having a hole shape.
[0007]
In these toner carriers, the resistance value of the carrier itself is adjusted to about 10 ⁵ to 10 ⁹ Ω in order to obtain an electric field serving as a driving force for transferring the carried toner to an image forming body such as a photoconductor. In many cases, the resistance of the resin coating layer 3a that covers the surface is set higher than that of the semiconductive elastic layer 3 in order to facilitate resistance adjustment. In this case, carbon black, metal powder, metal oxide, and the like are also used for adjusting the resistance of the resin coating layer 3a, as in the case of the semiconductive elastic layer 3.
[0008]
[Problems to be solved by the invention]
When an electrophotographic system using the developing roller (toner carrier) 1 is considered, particularly in order to obtain a high-quality image, a constant charge is always applied when the developer held on the developing roller reaches the image forming body. And a uniform charge state is required.
[0009]
That is, when high image quality is required for an image forming apparatus such as a printer, image defects such as image fogging often occur particularly when the charge amount of the toner is low. In particular, when conductive fine particles are contained on the surface of the roller, charge leakage occurs during charging of the toner, so that the toner charge amount cannot be maintained at a sufficiently high level, and such a problem is likely to occur.
[0010]
In this case, various charge control agents (CCA) are added to the surface of the developing roller in order to improve the charge amount of the toner, and a method of increasing the surface roughness in order to improve the triboelectric charging characteristics has been proposed. If the photoconductor is contaminated by CCA or the surface roughness is large, problems such as an increase in the amount of toner conveyed and an excessive supply of the developer may occur.
[0011]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and keeps toner highly charged, furthermore, prevents occurrence of white image fog as much as possible, and reliably obtains high-quality images that can withstand high speeds. It is an object of the present invention to provide a method for inspecting a toner carrier that can be performed.
[0012]
Means for Solving the Problems and Embodiments of the Invention
The present inventor has conducted intensive studies to obtain a toner carrier capable of forming a high-quality image, and as a result, the electric force between the metal shaft and the surface, which has been regarded as important in a conventional developing roller (toner carrier), has been studied. Although the resistance is an important factor for the development characteristics, in particular, in the case of a roller having a resin coating layer (insulating layer) having a volume resistivity of more than 10 ¹² Ωcm on the surface, the toner charging amount is less than the electric resistance. The charge retention ability of the roller surface has a great effect, and the electric resistance value is controlled to a constant value over the entire surface of the roller and is not only uniform, but also the charge retention on the developing roller that affects the charging characteristics of the toner. It has been found that by optimizing the performance, it is possible to prevent image defects such as spots, uneven density, and white image fogging.
[0013]
Therefore, the present inventor further studied the evaluation of a proper electric resistance value and a good charge holding ability of the toner carrier. As a result, the toner carrier having the insulating layer on the outermost surface has a temperature of 22 ° C. and 50%. In the measurement environment of RH, the corona discharge is performed by applying a voltage of 8 kV to a corona discharger having an electric resistance value of 10 ⁴ to 10 ⁸ Ω when a voltage of 100 V is applied to the toner carrier and having a distance of 1 mm from the surface. If the minimum value of the surface potential 0.1 second after the generation and charging of the surface is 100 V to 1 kV or less, this toner carrier keeps the toner highly charged, and furthermore, the occurrence of white image fog The present invention has been completed by finding that high-quality images that can withstand high-speed operation can be reliably obtained by preventing as much as possible.
[0014]
Accordingly, the present invention provides a semiconductive layer formed on the outer periphery of a good conductive shaft, and a resin coating layer having a volume resistivity exceeding 10 ¹² Ωcm is formed as an outermost layer on the semiconductive layer. A non-magnetic one-component developer is supported to form a thin layer of the developer, and in this state, the developer is supplied to the surface of the image forming body by contacting or approaching the image forming body, thereby forming the image. A method for inspecting a toner carrier that forms a visible image on a formed body, wherein the electric resistance at the time of application of 100 V is measured to check that the electric resistance is 10 ⁴ to 10 ⁸ Ω, and When a voltage of 8 kV is applied to a corona discharger arranged at a distance of 1 mm from the surface to generate corona discharge and charge the surface, the surface potential after 0.1 second is measured, and the minimum value is 100 V ~ 1kV There is provided an inspection method of the toner carrier to.
[0015]
Hereinafter, the present invention will be described in more detail.
According to the inspection method of the present invention, a semiconductive layer 3 is formed on the outer periphery of a good conductive shaft 2 like a roller 1 shown in FIG. 1, and a resin coating layer 3a is further formed on the semiconductive layer 3. In the present invention, the electric resistance of such a toner carrier when 100 V is applied is measured, and it is determined that the electric resistance is 10 ⁴ to 10 ⁸ Ω. Inspection, and applying a voltage of 8 kV to a corona discharger arranged at a distance of 1 mm from the surface to generate a corona discharge and measure the surface potential after 0.1 second when the surface is charged. It is to check that the minimum value is 100 V to 1 kV.
[0016]
Here, the toner carrier to be inspected by the inspection method of the present invention will be described. In the toner carrier of FIG. 1, the shaft 2 may be any one having good conductivity. A metal shaft such as a metal core bar made of a solid body made of metal such as iron, stainless steel, or aluminum, or a metal cylindrical body having a hollow inside is usually used.
[0017]
Next, the semiconductive layer 3 formed on the outer periphery of the shaft 2 is formed by blending an electronic conductive agent such as carbon black or an ionic conductive agent such as sodium perchlorate into a single elastomer or a foam obtained by foaming the elastomer. It is formed of a semiconductive elastic body whose value is adjusted.
[0018]
Examples of the elastomer include silicone rubber, EPDM, NBR, natural rubber, SBR, butyl rubber, chloroprene rubber, acrylic rubber, epichlorohydrin rubber, EVA, polyurethane, and a mixture thereof. In particular, silicone rubber, EPDM, Epichlorohydrin rubber polyurethane is preferably used. In addition, these elastomers can also be used as a foam body that is chemically foamed by using a foaming agent, or foamed by mechanically entrapped air, such as a polyurethane foam.
[0019]
Examples of the conductive agent incorporated in the semiconductive layer 3 include an electronic conductive agent, for example, conductive carbon such as Ketjen black, acetylene black, SAF, ISAF, HAF, FEF, GPF, SRF, and FT. , MT, etc. carbon for rubber, carbon for color (ink) subjected to oxidation treatment, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, Examples thereof include metals and metal oxides such as germanium, and conductive polymers such as polyaniline, polypyrrole, and polyacetylene. The compounding amount of these electronic conductive agents is preferably 1 to 50 parts by weight, especially 5 to 40 parts by weight, based on 100 parts by weight of the elastomer.
[0020]
Examples of ionic conductive agents include perchlorates, chlorates, hydrochlorides, bromine salts such as tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium and modified fatty acid dimethylethylammonium. Ammonium salts such as acid salts, iodate salts, borofluoride salts, sulfate salts, ethyl sulfate salts, carboxylate salts, and sulfonates; alkali metals such as lithium, sodium, potassium, calcium, and magnesium; and alkaline earth salts Metal perchlorates, chlorates, hydrochlorides, bromates, iodates, borofluorides, sulfates and the like can be mentioned. The compounding amount of these ionic conductive agents is usually suitably used in the range of 0.01 to 5 parts by weight, particularly 0.05 to 2 parts by weight based on 100 parts by weight of the elastomer.
[0021]
The conductive agent may be used alone or in combination of two or more. In this case, an electronic conductive agent and an ionic conductive agent may be combined.
[0022]
The semiconductive layer 3 is not particularly limited, but preferably has a resistance of 10 ³ to 10 ¹⁰ Ωcm, particularly preferably 10 ⁴ to 10 ⁸ Ωcm, depending on the composition of the conductive agent. If the resistance value is less than 10 ³ Ωcm, the electric charge may leak to the photosensitive drum or the like, or the toner carrier itself may be broken by the voltage. On the other hand, if the resistance value exceeds 10 ¹⁰ Ωcm, the ground fogging is likely to occur. .
[0023]
If necessary, a crosslinking agent and a vulcanizing agent can be added to the semiconductive layer 3 in order to convert the elastomer into a rubbery substance. In this case, a vulcanization aid, a vulcanization accelerator, a vulcanization acceleration aid, a vulcanization retarder and the like can be used in both cases of organic peroxide crosslinking and sulfur crosslinking. Furthermore, peptizing agents, foaming agents, plasticizers, softeners, tackifiers, antiblocking agents, separating agents, mold release agents, extenders, coloring agents that are commonly used as rubber compounding agents other than those described above. Etc. can be added.
[0024]
Further, when the semiconductive layer 3 is formed using polyurethane or EPDM as a base material, for example, nigrosine, triaminophenylmethane, a cationic dye, etc., for the purpose of controlling the amount of toner charge on the surface when used as a developing roller. Various charge control agents, fine powders of silicone resin, silicone rubber, nylon and the like can be added. In this case, the amount of these additives is preferably 1 to 5 parts by weight of the charge control agent and 1 to 10 parts by weight of the fine powder, based on 100 parts by weight of the polyurethane or EPDM.
[0025]
The hardness of the semiconductive layer 3 is not particularly limited, but is preferably 60 ° or less, particularly 25 to 55 ° on a JIS-A scale. In this case, if the hardness exceeds 60 °, for example, when used as a developing roller, a contact area with a photosensitive drum or the like becomes small, and there is a possibility that good development cannot be performed. Further, the toner is damaged, and the toner adheres to the photoreceptor or the layered blade, and the image is likely to be defective. Conversely, if the hardness is too low, the frictional force between the photoconductor and the stratification blade becomes large, and image defects such as jitter may occur. In addition, since the semiconductive layer 3 is used in contact with a photoreceptor, a laminating blade, or the like, it is preferable to reduce the compression set as much as possible even when the hardness is set to a low hardness. % Is preferable.
[0026]
Although the surface roughness of the semiconductive layer 3 is not particularly limited, it is preferably 15 μmRz or less, particularly preferably 1 to 10 μmRz in terms of JIS 10-point average roughness. When the surface roughness exceeds 15 μmRz, the thickness of the toner layer of the one-component developer (toner) and the uniformity of charging may be impaired. However, by adjusting the surface roughness to 15 μmRz or less, the adhesion of the toner can be improved. It is possible to more reliably prevent image deterioration due to abrasion of the roller during long-term use.
[0027]
As shown in FIG. 1, on the toner carrier to be inspected, an insulating resin coating layer 3a is formed on the semiconductive layer 3 in order to adjust the resistance and control the charge amount and the transport amount of the toner. You. The resin forming the resin coating layer 3a is not particularly limited, and may be any resin that is non-staining and does not adhere to an image forming body such as a photosensitive drum. Specifically, polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, melamine resin, urea resin, silicone resin, polyvinyl resin Butyral resin and the like can be mentioned, and these can be used alone or in combination of two or more. Further, modified resins in which a specific functional group is introduced into these resins can also be used.
[0028]
The resin coating layer 3a may have a single layer structure or a multi-layer structure of two or more layers. When the resin coating layer 3a has a multi-layer structure of two or more layers, at least the outermost layer may have an insulating property. Can be made conductive by adding a conductive agent. In this case, the conductive agent may be the same as the conductive agent used for the semiconductive layer 3. In the present invention, if the volume resistivity is 10 ¹² Ωcm or more, it is assumed to be insulating.
[0029]
Further, it is preferable to introduce a crosslinked structure into the resin coating layer 3a in order to improve the mechanical strength and environmental resistance. In this case, the cross-linking structure is introduced by a self-cross-linking method of cross-linking with heat, a catalyst, air (oxygen), moisture (water), ultraviolet light, or the like according to the molecular structure of the resin constituting the resin coating layer 3a; There is a method in which a crosslinking agent or another crosslinking resin is reacted.
[0030]
It should be noted that various other additives can be added to the resin coating layer 3a as needed.
[0031]
As a method of forming the resin coating layer 3a on the semiconductive layer 3, a method of surface-treating the semiconductive layer 3 with a resin solution containing the resin component and the additive is preferably employed. In this case, after preparing the resin solution, the surface treatment can be performed by a spray method, a roll coater method, a dipping method, or the like. The solvent for preparing the resin solution may be any solvent as long as it dissolves the above resin, but is usually methanol, ethanol, lower alcohols such as isopropanol, acetone, methyl ethyl ketone, ketones such as cyclohexanone, Toluene, xylene and the like are preferably used.
[0032]
Although the thickness of the resin coating layer 3a is not particularly limited, it is usually preferably 3 to 50 μm, particularly preferably about 5 to 30 μm. In some cases, the charging performance of the surface layer cannot be ensured. On the other hand, when the thickness exceeds 50 μm, the surface of the toner carrier becomes hard, giving damage to the toner and causing the toner to adhere to an image forming body such as a photoconductor or a layered blade. This may cause an image defect.
[0033]
In the inspection method of the present invention, the above-mentioned toner carrier is first inspected to determine whether the electric resistance when 100 V is applied is 10 ⁴ to 10 ⁸ Ω. In this case, if the resistance value is less than 10 ⁴ Ω, gradation control becomes extremely difficult, and if an image forming body such as a photoconductor has a defect, a bias leak may occur. On the other hand, if the resistance value exceeds 10 ⁸ Ω, for example, when developing the toner on a latent image holding member such as a photoconductor, the developing bias causes a voltage drop due to the high resistance of the toner holding member itself, and the developing bias is insufficient. The developing bias cannot be secured, and a sufficient image density cannot be obtained. The resistance value can be measured, for example, by pressing the toner carrier against a flat or cylindrical counter electrode at a predetermined pressure, applying a voltage of 100 V between the shaft and the counter electrode, and measuring the current value at that time. Note that a more preferable range of the resistance value is set to 10 ⁵ to 10 ⁷ Ω.
[0034]
As described above, it is important to appropriately and uniformly control the resistance value of the toner carrier in order to maintain the electric field strength for moving the toner properly and uniformly. These are necessary but not sufficient conditions for proper and uniformity. That is, according to the study of the present inventor, it is important to control the charge holding ability of the surface of the toner carrier and keep it uniform in addition to the resistance value in order to optimize and equalize the toner charge amount. found. In this case, the surface charge holding ability is usually examined by measuring a surface resistance by arranging a pair of electrodes on the surface of the toner carrier and applying a constant voltage between the two electrodes. Since it flows not only through the carrier but also inside the carrier, accurate evaluation of the carrier surface cannot be performed. In addition, although improvement in accuracy by the four-terminal method has been proposed, particularly in the case of a stacked toner carrier, the surface layer is considerably thin, and it is difficult to characterize only the surface in this method. is there. Therefore, the characteristic values obtained by these conventional measurement methods cannot accurately represent the surface charge holding ability.
[0035]
Therefore, in the present invention, in addition to the above-described resistance value when 100 V is applied, a voltage of 8 kV is applied to a corona discharger disposed at a distance of 1 mm from the surface of the toner carrier to generate corona discharge and charge the surface. In this case, the surface charge holding ability is evaluated based on the minimum value of the surface potential after 0.1 second, and it is checked that the minimum value is 100 V to 1 kV. In this case, if the minimum value is less than 100 V, the charge on the roller surface is removed very quickly, and a sufficient amount of toner charge cannot be obtained, so that the object of the present invention cannot be achieved. When the voltage exceeds 1 kV, the resistance of the carrier often substantially exceeds the above-mentioned range in many cases. However, in this case, the toner charge amount becomes too high, and the effective developing bias becomes lower in the developing process. A phenomenon that the potential of the high potential portion of the body is exceeded and the toner is developed on a white background portion, that is, a so-called high voltage fog occurs.
[0036]
In order to increase the charge retention capability of the surface in this way, it is effective to coat the surface of the carrier with the insulating resin having the above-mentioned 10 ¹² Ωcm or more, but on the other hand, the resistance of the carrier also increases, As described above, a sufficient developing bias cannot be secured, which may result in an image defect. In this case, by adjusting the thickness of the resin coating layer 3a, the resistance value of the carrier may be adjusted to the range of 10 ⁴ to 10 ⁸ Ω.
[0037]
Further, as described above, in order to adjust the resistance value of the toner carrier to the above-mentioned 10 ⁴ to 10 ⁸ Ω, it is important to control the thickness of the outermost insulating resin layer. If the thickness is too small, the surface roughness of the semiconductive layer 3 greatly affects the surface, and the surface roughness becomes rough. In this case, the toner conveyance amount becomes excessive, which is not appropriate especially when high image quality such as a color image is assumed. For this reason, as described above, the resin coating layer is composed of two or more layers, a conductive resin layer is formed as an inner coating layer between the semiconductive layer 3 and the outermost insulating layer, and the surface roughness is reduced. It is preferred to lower it. The surface roughness of the toner carrier is preferably 5 μm or less, particularly preferably 3 μm or less in terms of JIS 10-point average roughness Rz.
[0038]
The measurement of the minimum value of the surface potential can be performed by, for example, the apparatus shown in FIG. That is, the both ends of the shaft 2 of the toner carrier 1 are gripped by the chuck 11, the toner carrier 1 is supported, and the small corotron discharger 12 and the surface voltmeter 13 are juxtaposed at a predetermined interval. The unit is disposed opposite to the surface of the toner carrier 1 with a gap of 1 mm, and the measuring units 12 and 13 are fixed from one end to the other end of the toner carrier 1 while the toner carrier 1 is kept stationary. A method of measuring the surface potential 0.1 second after the charging while giving the surface charge by moving at a speed is suitably adopted.
[0039]
The toner carrier to be inspected in the present invention is generally used as a developing roller in an image forming apparatus such as a developing apparatus using a non-magnetic one-component developer. Specifically, as shown in FIG. 4, between the toner applying roller 4 for supplying the toner and the photosensitive drum 5 holding the electrostatic latent image, the photosensitive drum 5 is disposed in contact with or close to the photosensitive drum 5. A developing roller 1 provided with toner 6 supplied to the developing roller 1 by a toner coating roller 4, which is formed into a uniform thin layer by a layering blade 7, and further, toner is transferred from the thin layer to a photosensitive drum 5. The latent image is visualized by supplying toner to the electrostatic latent image on the photosensitive drum 5 and adhering toner. Note that the details of FIG. 4 have been described in the related art, and thus description thereof will be omitted.
[0040]
In addition, the inspection object of the inspection method of the present invention is not limited to the developing roller used in such a developing device. The toner carrier that forms an image by directly flying through the device can be inspected well.
[0041]
【Example】
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.
[0042]
[Examples 1 and 2 and Comparative Examples 1 and 2]
Propylene oxide and ethylene oxide are added to glycerin, and 100 parts (parts by weight, hereinafter the same) of polyether polyol (OH value: 33) having a molecular weight of 5000, 1.0 part of 1,4-butanediol, a silicone surfactant 1.5 parts, 0.5 parts of nickel acetylacetonate, 0.01 parts of dibutyltin dilaurate and 0.01 parts of sodium perchlorate were added and mixed with a mixer to prepare a polyol composition.
[0043]
After stirring and defoaming the polyol composition under reduced pressure, 17.5 parts of urethane-modified MDI was added, stirred for 2 minutes, and then poured into a mold heated to 110 ° C. and cured for 2 hours. An elastic layer was formed on the outer periphery of the metallic shaft to obtain a roller having the structure shown in FIG. The surface of the obtained roller was polished to adjust the surface to a JIS 10-point average roughness of 7 μmRz.
[0044]
The resin shown in Table 1 below was dissolved in methyl ethyl ketone (MEK), and the conductive agent shown in Table 1 was further added to prepare a paint. The roller was immersed in the paint, pulled up, and heated and dried. Thus, a resin coating layer was formed, and four types of developing rollers (toner carriers) shown in Table 1 were obtained. In addition, the thickness of the resin coating layer was adjusted by adjusting the resin concentration in the paint as follows. Example 1: 15% (outside), 20% (inside), Example 2: 10%, Comparative Example 1: 30%, Comparative Example 2: 35%. The surface roughness of each of the obtained rollers was as shown in Table 1.
[0045]
With respect to each of the obtained developing rollers (toner carrier), a resistance value when a voltage of 100 V was applied between the developing roller and the counter electrode (metal drum) was measured using the rotational resistance measuring device shown in FIG. Table 1 shows the results.
[0046]
Further, using the apparatus shown in FIG. 2, a voltage of 8 kV was applied to the roller to charge the roller surface by corona discharge, and the measuring units 12 and 13 were moved at a speed of 200 mm / sec. The surface potential after 1 second was measured. The shape and dimensions of the measuring unit are as shown in FIG. By this method, the entire roller surface was measured, and the minimum value among them was defined as the surface potential value. In addition, the difference between the maximum and the minimum was arranged out of the total measured values. Table 1 shows the results. The measurement environment was controlled at a temperature of 22 ° C. and a humidity of 50%.
[0047]
Next, each roller was attached as a developing roller 1 to the developing device (image forming device) shown in FIG. 4, and development (image formation) was performed, and the obtained image was evaluated. Table 1 shows the results.
[0048]
[Table 1]

* 1: "L6" manufactured by Degussa
* 2: Toray “CM8000”
* 3: Resin comparison
As is evident from the results shown in Table 1, in addition to the electric resistance, an example in which the surface charge holding ability was inspected and evaluated based on the minimum value of the surface potential 0.1 second after corona charging, and this was optimized. It was confirmed that the first and second rollers can reliably form a good image.
[0050]
【The invention's effect】
As described above, according to the inspection method of the present invention, the toner is kept highly charged, the occurrence of white image fog is prevented as much as possible, and a high-quality image that can withstand high-speed operation is surely obtained. It is possible to surely inspect the toner carrier obtained.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of the toner carrier of the present invention.
FIG. 2 is a schematic diagram illustrating an example of an apparatus for measuring a surface potential of a toner carrier.
FIG. 3 is a schematic plan view showing shapes and dimensions of measurement units used in Examples and Comparative Examples.
FIG. 4 is a schematic sectional view showing an example of the image forming apparatus (developing apparatus) of the present invention.
FIG. 5 is a schematic diagram showing a rotational resistance measuring instrument used in Examples and Comparative Examples.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 developing roller 2 shaft 3 semiconductive layer 3 a resin coating layer 4 toner coating roller 5 photosensitive drum (image forming body)
6. Toner (non-magnetic one-component developer)
7 Layering blade 8 Transfer unit 9 Cleaning unit 10 Cleaning blade 11 Chuck 12 Corotron discharger (Corona discharger)
13 Surface electrometer

Claims (2)

A semiconductive layer is formed on the outer periphery of the good conductive shaft, and a resin coating layer having a volume resistivity exceeding 10 ¹² Ωcm is formed as an outermost layer on the semiconductive layer. To form a thin layer of the developer, and in this state, contacting or approaching the image forming body and supplying the developer to the surface of the image forming body to form a visible image on the image forming body A method for inspecting a toner carrier to be formed,
The electric resistance at the time of application of 100 V was measured to check that the electric resistance was 10 ⁴ to 10 ⁸ Ω. A method for inspecting a toner carrier, comprising: measuring a surface potential after 0.1 second when a surface is charged by generating corona discharge; and inspecting that a minimum value is 100 V to 1 kV. When a voltage of 8 kV was applied to a corona discharger arranged at an interval of 1 mm from the surface to generate corona discharge and charge the surface, the surface potential after 0.1 second was measured. The method for inspecting a toner carrier according to claim 1, wherein the inspection is performed at a voltage of 200 V.

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