JP2007193183A - Solid lubricant block, its manufacturing method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid lubricant block capable of stably supplying lubricant to an image carrier, its manufacturing method and an image forming apparatus. <P>SOLUTION: The solid lubricant block supplying the lubricant to the image carrier while it is pressed by a pressing means has hardness inclination. The image forming apparatus is equipped with the solid lubricant block. In the manufacturing method of the solid lubricant block, the hardness inclination is applied to the solid lubricant block by giving temperature distribution to the die face of a molding die and controlling cooling speed in a stage for cooling and solidifying a heated and melted fatty acid compound in the molding die. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid lubricant block, a method for producing the same, and an image forming apparatus including the solid lubricant block. More specifically, a solid lubricant block, a manufacturing method thereof, and an image forming apparatus for stably supplying a lubricant to an image carrier for holding a toner image, extending the life of the image carrier, and improving image quality It is about.

  In an image forming apparatus such as a copying machine, a printer, and a facsimile machine using an electrophotographic method, a uniformly charged photosensitive member is irradiated with writing light (exposure) modulated by image data to thereby sensitize the photosensitive member. An electrostatic latent image is formed on the body, and toner is supplied to the photoconductor on which the electrostatic latent image is formed by a developing unit to form a toner image on the photoconductor and develop it. The image forming apparatus transfers the toner image on the photoconductor to the recording paper at the transfer unit, and then heats and pressurizes the toner transferred onto the recording paper at the fixing unit, and fixes the toner remaining on the surface of the photoconductor. The part is collected by a method such as scraping with a cleaning blade.

  However, when the toner remaining on the surface of the photosensitive member is scraped off by the cleaning blade, if the frictional force between the cleaning blade and the photosensitive member is high, the blade friction and the surface of the photosensitive member may be scraped, and the respective life may be shortened. It was.

  In an image forming apparatus using such an electrophotographic method, conventionally, a lubricant is applied to the surface of the photoconductor to reduce the coefficient of friction on the surface of the photoconductor, thereby preventing unnecessary toner adhesion. . In particular, in an image forming apparatus that cleans residual toner on the surface of a photoconductor with a cleaning blade, when a lubricant is supplied onto the photoconductor, the coefficient of friction between the photoconductor and the cleaning blade is reduced, and the cleaning performance is improved. And extended the life of the cleaning blade.

  As a mechanism for applying the lubricant to the image carrier, a system in which the solid lubricant block is pressed against the brush with a spring and the lubricant is applied to the image carrier while being shaved with the brush is well known. However, in this method, as the solid lubricant block wears, the spring displacement decreases, so the force pressing the solid lubricant block against the brush tends to decrease. It was difficult to apply to an image carrier. As a result, the amount of solid lubricant applied was reduced, and the film abrasion (wear) of the photoreceptor was remarkable at the end of durability.

  In addition, in an image forming apparatus that applies to an image carrier while shaving a solid lubricant block with a brush, the bristle of the brush needs to be rigid enough to scrape the solid lubricant block. However, if the rigidity is too large, there is a problem that the film removal of the image carrier is promoted, so it is necessary to reduce the brush rigidity. When the rigidity of the brush is reduced, there is a problem that it is difficult to obtain a solid lubricant block having a moderately low hardness corresponding to this.

On the other hand, as disclosed in Patent Document 1, as a method for producing a solid lubricant, a method of cooling and solidifying sequentially from the lower part to the upper part has been proposed. However, in such a method, the solidification of the fatty acid or the fatty acid metal salt proceeds from one direction, and as a result, the crystals tend to have a layered, dense and uniform structure and become hard. For example, a hard solid lubricant block having a uniform hardness of H to 2H in pencil hardness is formed. When a solid lubricant block having such hardness is used in an image forming apparatus that uses, for example, an organic photoreceptor whose main material is polycarbonate resin or the like as an image carrier, an application member is used to scrape the solid lubricant block. However, there is a problem that the rigidity of the brush is required, and as a result, the film of the photoconductor is promoted. Moreover, the hardness of the solid lubricant block is uniform, and as described above, as the solid lubricant block is consumed due to durability, the spring force of the pressing means decreases, so that the lubricant for the image carrier The stable supply of was not achieved.
JP-A-7-26278

  An object of the present invention is to provide a solid lubricant block capable of stably supplying a lubricant to an image carrier, a manufacturing method thereof, and an image forming apparatus.

  In order to achieve the above object, a solid lubricant block having an appropriate hardness gradient is manufactured and provided in an image forming apparatus.

  That is, the present invention provides a solid lubricant block that supplies a lubricant to an image carrier while being pressed by a pressing means, and has a hardness gradient, and includes the solid lubricant block and the solid lubricant block The present invention relates to an image forming apparatus.

  The present invention also provides a continuous hardness gradient by providing a temperature distribution to the mold surface of the mold and controlling the cooling rate in the process of cooling and solidifying the fatty acid compound melted by heating in the mold. The present invention relates to a method for producing a solid lubricant block.

  The present invention also provides a stepwise hardness gradient by manufacturing a plurality of solid lubricant block portions having different hardnesses, and laminating and integrating the obtained solid lubricant block portions in a predetermined order. The present invention relates to a solid lubricant block manufacturing method.

  When the solid lubricant block is consumed, the pressing force of the pressing means such as a spring decreases. The solid lubricant block of the present invention has a hardness gradient in which the hardness increases in the pressing direction, the hardness of the surface on the image carrier side is relatively high in the initial use, and the hardness decreases with consumption. Even if the pressing force of the pressing means decreases, the pressure is effectively supplied, and a decrease in the lubricant supply amount can be suppressed. Therefore, there is almost no fluctuation in the supply amount over a long period of time, and the lubricant can be supplied stably. As a result, when the image bearing member is, for example, a photosensitive member, the coefficient of friction of the photosensitive member and its cleaning blade can be stably reduced, the cleaning performance can be improved, and the life of the photosensitive member and the cleaning blade can be extended. Become. In addition, for example, when the image carrier is an intermediate transfer member, the friction coefficient of the intermediate transfer member and its cleaning blade can be stably reduced, the cleaning performance can be improved, and the life of the intermediate transfer member and the cleaning blade can be extended. It becomes.

  In addition, when a lubricant application member is used, the solid lubricant block of the present invention can be arranged below or on the side of the application member without being limited in arrangement, so that the image forming apparatus The degree of freedom in design increases. Of course, the solid lubricant block of the present invention is disposed above the application member, and even when the lubricant is supplied by simply pressing the application member with its own weight, the effect of the present invention can be obtained and a complicated configuration is required. do not do.

  The solid lubricant block of the present invention is used in an image forming apparatus that supplies a lubricant to an image carrier while pressing the solid lubricant block with a pressing means. One embodiment of such an image forming apparatus is shown in FIG. FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus shown in FIG. 1 includes at least a cylindrical and rotatable photosensitive member (image carrier) 1, a charging device 2 for uniformly charging the surface of the photosensitive member, and an electrostatic latent image by exposing the photosensitive member. An exposure device 3 that creates an image, a developing device 4 that develops a toner image based on an electrostatic latent image, a transfer device 5 that transfers a toner image on a photoreceptor to a transfer body P, and a toner image on the transfer body A fixing device 6 for fixing the toner and a lubricant supply device 7 for supplying a lubricant to the photosensitive member, and further includes a cleaning device 8 such as a cleaning blade for cleaning residual toner on the photosensitive member. May be. The photoreceptor 1, charging device 2, exposure device 3, developing device 4, transfer device 5, fixing device 6, cleaning device 8, etc. used in the image forming apparatus arbitrarily use well-known electrophotographic technology. It doesn't matter.

  Hereinafter, the lubricant supply device 7 of the image forming apparatus in FIG. 1 will be described in detail. In the lubricant supply device 7 of FIG. 1, the solid lubricant block 70 supplies the lubricant to the photoreceptor 1 via the lubricant application member 72 while being pressed against the lubricant application member 72 by the pressing means 71. However, the present invention is not limited to this as long as the solid lubricant block 70 is pressed by the pressing means 71 and the lubricant is supplied to the photoreceptor. For example, in FIG. 1, the lubricant may be supplied directly to the photoreceptor 1 without using the lubricant application member 72.

  FIG. 2 shows an enlarged schematic view of the lubricant supply device 7 in the image forming apparatus of FIG. In FIG. 2, a lubricant application member (hereinafter sometimes simply referred to as “application member”) 72 is rotatably installed with a predetermined amount of biting into the photoreceptor 1. The solid lubricant block 70 (hereinafter, simply referred to as “block”) 70 can ensure a predetermined amount of biting by the application member 72 with respect to the block 70, and the pressing means 71 is used as the block 70 is consumed. It is installed so that it can move in the direction of the application member 72 by pressing. The pressing means 71 is fixedly installed on a stationary wall 73 such as a housing so that the block 70 can be moved in the direction of the application member 72 as the block 70 is consumed.

  The block 70 is pressed in the direction of the application member 72 by the pressing means 71 and is scraped by the application member 72 to supply and apply the lubricant to the photoreceptor 1. As the block 70 is consumed, the block 70 is further pressed and moved in the direction of the application member 72 by the pressing means 71, and continuously supplies the lubricant.

  The block 70 has a hardness gradient that increases in hardness in the pressing direction Dp. That is, in the block 70, the hardness is relatively high on the image carrier (photosensitive member 1) side (70a), and the pressing means 71 side (70b). Is relatively low. For this reason, since the hardness of the image carrier side 70a in the block 70 decreases with consumption, even if the pressing force of the pressing means decreases due to consumption, the block 70 can be continuously scraped and supplied with lubricant. , The decrease in the lubricant supply amount can be suppressed.

  The hardness gradient of the block 70 may be a hardness gradient in which the hardness is continuously increased, or a hardness gradient in which the hardness is increased stepwise as long as there is no inclined portion in which the hardness decreases in the pressing direction Dp. There may be. The hardness of the block 70 having the lowest hardness (the pressing means 71 side (70b)) and the highest hardness (for example, the image carrier side (70a)) is particularly limited as long as the object of the present invention is achieved. However, from the viewpoint of easily imparting a hardness gradient, it is preferable that the difference between them is one or more ranks in terms of pencil hardness, and particularly one rank to three ranks. . Specific examples of such preferable hardness combinations are shown below.

Maximum hardness-minimum hardness (A1) HF;
(A2) H-B;
(A3) H-2B;
(A4) H-3B;
(A5) HB-B;
(A6) HB-2B;
(A7) HB-3B;
(A8) F-2B;
(A9) F-3B;
(A10) B-3B;

(A11) B-2B;
(A12) H-HB;
(A13) 2H-H;
(A14) 2B-3B;
(A15) 3B-4B;
(A16) 4B-5B;
(A17) FB.

  Among the above combinations of hardness, more preferable are combinations (A1) to (A10), particularly (A8) and (A10).

  The above hardness is based on pencil hardness and can be measured by a general coating test method (JIS K5600-5-4: 1999, mechanical properties of coating film, scratch hardness (pencil method)). The inclination may be determined based on any hardness as long as the relative height can be determined.

  The substance constituting the block 70 is not particularly limited as long as it can impart lubricity, and usually a substance having a relatively low surface energy and being chemically inert is used. Specific examples include, for example, fatty acid compounds such as chain monocarboxylic acids and chain monohydroxymonocarboxylic acids, and one type of compound may be used alone, or two or more types of compounds may be used. A combination of compounds may be used. From the viewpoint of easily imparting a hardness gradient, the block is preferably composed of 50% by weight or more, particularly 80 to 100% by weight of the entire block, of a fatty acid compound, particularly a chain monocarboxylic acid.

The fatty acid compound is solid at 25 ° C., and preferably has a melting point of 60 ° C. or higher, particularly 80 to 200 ° C.
As such preferred chain-type monocarboxylic acids, those having 4 to 30 carbon atoms can be used. Specific examples include stearic acid, heptadecylic acid, palmitic acid, pentadecylic acid, myristic acid, tridecylic acid, lauric acid, and behenic acid. A saturated chain monocarboxylic acid having 12 to 30 carbon atoms such as melicic acid, arachidic acid, margaric acid (n-heptadecanoic acid) and arachidic acid, and 4 to 24 carbon atoms such as crotonic acid, elaidic acid and nervonic acid. Examples include unsaturated chain monocarboxylic acids, and metal salts thereof, and metal salts of oleic acid.
Specific examples of preferable chain monohydroxymonocarboxylic acids include unsaturated monohydroxymonocarboxylic acids having 10 to 25 carbon atoms such as ricinoleic acid, and metal salts thereof.
Examples of the metal that can constitute the metal salt of the fatty acid compound usually include zinc, barium, calcium, magnesium, sodium, potassium, aluminum, lithium, beryllium, silver, iron, copper, and the like.

  Of the above specific examples of the fatty acid compounds, chain monocarboxylic acids are more preferable from the viewpoint of imparting a hardness gradient, more preferably saturated chain monocarboxylic acids and metal salts thereof, particularly those having 16 to 22 carbon atoms. Specifically, zinc stearate, magnesium stearate, and calcium stearate.

  From the viewpoint of preventing cracks on the block surface, it is preferable to use a fatty acid compound having a relatively low melting point among the above specific examples. Examples of low melting point fatty acid compounds include calcium oleate (melting point 84 ° C.), calcium ricinoleate (melting point 74 ° C.), zinc oleate (melting point 70 ° C.), and zinc ricinoleate having a melting point in the range of 60 to 100 ° C. (Melting point: 94 ° C.). Examples of the high melting point fatty acid compound in the case of using such a low melting point fatty acid compound include zinc stearate, magnesium stearate, calcium stearate having a melting point in the range of 120 to 200 ° C. The content ratio of the low melting point fatty acid compound and the high melting point fatty acid compound, which is preferable from the viewpoint of preventing cracks, is preferably 40/60 to 5/95, particularly 20/80 to 5/95 in terms of weight ratio (low melting point / high melting point). It is.

When using a fatty acid compound, cracking can also be prevented by using an alcohol having a melting point of 60 to 70 ° C. in combination. As such alcohols, for example, straight-chain alcohols of the carbon number of C ₁₈ -C _25, particularly arachyl alcohol, behenyl alcohol, and the like.

  The following method (1) and method (2) may be mentioned as a method for producing a block comprising a fatty acid compound and having a hardness gradient.

  Method (1): In the process of cooling and solidifying the heat-melted fatty acid compound in the mold, the mold surface of the mold has a temperature distribution to control the cooling rate. That is, when the molten fatty acid compound is cooled and solidified in the mold, the molecular arrangement is controlled by giving the temperature distribution to the mold surface of the mold and controlling the cooling rate, resulting in continuous hardness. Gives a slope. Specifically, since the fatty acid compound molecule has a hydrophilic group part (◯) and a hydrophobic group part (−) in one molecule as shown in FIG. By slow cooling, the crystals are regularly arranged, and after passing through a disk-like structure, finally a crystal having a layered structure is formed. On the other hand, upon rapid cooling, such an ordered arrangement is not achieved and forms an amorphous. At this time, the hardness of the crystal is relatively high, and the hardness of the amorphous is relatively low. A hardness gradient is imparted using such a difference in hardness based on the cooling rate.

  Specifically, for example, as shown in FIGS. 4 (A) and 4 (B), a mold having alternating temperature adjusting devices 20 and 21 that can be individually adjusted is prepared, and heated and melted in the mold. Pour the fatty acid compound (melting process). FIG. 4 (A) is a top plan view of a mold, and by using such a mold, four solid lubricant blocks of the present invention can be manufactured at one time. FIG. 4B is a cross-sectional view taken along the line AA in FIG. Next, the temperature adjusting devices 20 and 21 are used to cool the mold surface with a temperature distribution. That is, the mold surface 30 in which the temperature adjusting device 20 is embedded and the mold surface 31 in which the temperature adjusting device 21 is embedded are adjusted to different temperatures below the melting point of the fatty acid compound by the temperature adjusting devices 20 and 21, and held for a predetermined time. (Cooling step 1). If desired, thereafter, the mold surface 30 and the mold surface 31 are adjusted to a lower temperature while maintaining a temperature gradient and held for a predetermined time (cooling step 2). Such a cooling operation may be repeated until the temperature of the mold surface set to a relatively high temperature becomes about 50 ° C. or less (cooling step 3 and subsequent steps). Adjusting to a lower temperature while ensuring a temperature gradient is a temperature at which the temperature difference between the mold surface 30 and the mold surface 31 when the cooling is performed in the immediately preceding cooling process is substantially maintained. It means that each temperature is adjusted to be lower than that of the immediately preceding cooling step.

In any cooling step, the temperature of the mold surfaces 30 and 31 and the difference between them and the holding time are not particularly limited as long as a predetermined hardness gradient is given, but the following ranges are appropriate. Mp means the melting point of the fatty acid compound used. Tp is the temperature of the mold surface set to a relatively high temperature in the immediately preceding cooling step.
The temperature difference of the mold surface in the cooling step 1 is suitably 20 to 40 ° C., particularly 25 to 35 ° C., and the holding time is suitably 10 to 50 minutes, particularly 20 to 40 minutes. The temperature of the mold surface set at a relatively high temperature is suitably “Mp-10” to “Mp-3” ° C., particularly “Mp-4” to “Mp-6” ° C.

  The temperature difference of the mold surface in the cooling step after the cooling step 2 is suitably 20 to 40 ° C., particularly 25 to 30 ° C., and the holding time is suitably 15 to 50 minutes, particularly 20 to 40 minutes. The temperature of the mold surface set at a relatively high temperature is suitably “Tp-40” to “Tp-5” ° C., particularly “Tp-30” to “Tp-10” ° C.

For example, when manufacturing a block made of zinc stearate (melting point 125 ° C.) and having a hardness gradient, the following method can be followed. First, molten zinc stearate heated to 170 ° C. is poured into the mold shown in FIG. Next, the mold surface 30 is adjusted to 90 ° C., the mold surface 31 is adjusted to 120 ° C., and the cooling step 1 is held for 30 minutes, and the mold surface 30 is adjusted to 70 ° C. and the mold surface 31 is adjusted to 100 ° C. After performing the cooling step 2 held for 30 minutes, the mold surface 30 is adjusted to 50 ° C., the mold surface 31 is adjusted to 70 ° C., and the cooling step 3 is held for 30 minutes. After cooling, a block having a pencil hardness of 2B on the surface in contact with the mold surface 30 and a pencil hardness of F on the surface in contact with the mold surface 31 is obtained.
The molding temperature control may be appropriately changed depending on the size of the block, the degree of hardness gradient, and the type of lubricant.

  From the viewpoint of increasing the hardness gradient, it is preferable to use one type of fatty acid or fatty acid metal salt as the fatty acid compound that is heated and melted in the method (1).

  Method (2): A plurality of solid lubricant block portions having different hardnesses are manufactured, and the obtained solid lubricant block portions are laminated in a predetermined order and integrated. At this time, since the hardness is almost uniform in each block portion, a graded hardness gradient is provided as a result.

  When manufacturing a plurality of block portions having different hardnesses, the amount of crystal nuclei is adjusted and the rate of crystal precipitation is controlled in the process of cooling and solidifying the fatty acid compound that has been heated and melted in a mold. That is, for example, as shown in FIG. 5, when the fatty acid compound 51 heated and melted is cooled and solidified in the mold 50, the amount of crystal nuclei 52 is adjusted and the rate of crystal precipitation is controlled, The arrangement is controlled, and as a result, block portions having different hardnesses are manufactured.

  For example, two or more fatty acid compounds having different melting points are selected and the mixing ratio thereof is adjusted. Subsequently, the mixture is heated and melted at a temperature not higher than the melting point of the fatty acid compound having the highest melting point among the plurality of types of fatty acid compounds having different melting points (hereinafter simply referred to as “fatty acid compound for crystal nucleus”). Cool naturally and solidify. That is, when those mixtures are heated and melted at a temperature not higher than the melting point of the fatty acid compound for crystal nuclei among a plurality of types of fatty acid compounds having different melting points, only the fatty acid compound for crystal nuclei is present as a solid. Become. When this mixed liquid is cooled and solidified, a substance having a relatively low melting point is precipitated with the fatty acid compound existing as a solid as a nucleus, and crystals grow in various places. Therefore, when the amount of the fatty acid compound for crystal nuclei is increased, the rate of crystal precipitation is faster, and the regular part of the molecular arrangement is dispersed in small units. As a result, the fatty acid compound molecules are arranged relatively randomly as a whole. . That is, as the mixing ratio of the fatty acid compound for crystal nuclei increases, the fatty acid compound molecules are randomly arranged, so that the hardness of the obtained block portion is lowered. On the other hand, as the mixing ratio of the fatty acid compound for crystal nuclei decreases, crystallization is less likely to occur and the rate of crystal precipitation is slower. Therefore, the fatty acid compound molecules are arranged relatively regularly, and the hardness of the resulting block portion increases. The content ratio of the fatty acid compound for crystal nuclei in each block part is preferably adjusted within a range of 3 to 30% by weight, particularly 5 to 20% by weight, based on the total fatty acid compound.

  Specifically, when zinc stearate (melting point: 125 ° C.) and barium stearate (melting point: 225 ° C.) are used as the fatty acid compound, the content ratio of barium stearate is, for example, 0 to 15 with respect to the total fatty acid compound. The hardness of the obtained block part can be controlled in the range of H-3B by changing between weight%.

  Further, for example, in the above method, it is possible to easily manufacture lubricant block portions having different hardnesses by using other crystal nuclei that do not contaminate the photoreceptor instead of the fatty acid compound for crystal nuclei. Examples of crystal nuclei that do not contaminate the photoreceptor include inorganic fine particles such as silicon oxide, aluminum oxide, titanium oxide, strontium titanate, calcium titanate, polyacrylic acid, nylon, polyethylene terephthalate, PTFE (polytetrafluoroethylene), etc. Resin fine particles and the like. That is, when one or more types of fatty acid compounds are selected, crystal nuclei are added thereto, and the selected fatty acid compounds are heated and melted at a temperature at which all the selected fatty acid compounds are melted, naturally cooled at room temperature, and solidified. A substance having a relatively low melting point precipitates with the crystal nucleus as a nucleus. At this time, the larger the amount of crystal nuclei, the faster the rate of crystal precipitation, and the fatty acid compound molecules are randomly arranged, so that the hardness of the obtained block portion is lowered. On the other hand, as the number of crystal nuclei decreases, crystallization is less likely to occur and the rate of crystal precipitation is slower, so that the fatty acid compound molecules are arranged relatively regularly and the hardness of the resulting block portion is increased. The heating temperature for melting in such a method is usually 170 to 220 ° C., and even if the crystal nucleus is a resin fine particle, it does not melt. The content ratio of the crystal nuclei in each block part is preferably adjusted within the range of 3 to 20% by weight, particularly 5 to 15% by weight, based on the total fatty acid compounds.

  According to these methods, lubricant block portions having different hardnesses can be easily manufactured, and the block portions are laminated and integrated in a predetermined order as shown in FIG. The block 70 having an inclination can be easily manufactured. In FIG. 5, the number of laminated lubricant block portions having different hardnesses is 3, but is not limited to this as long as a graded hardness gradient can be provided. For example, the block is a block portion having two layers or four layers or more. It may consist of For example, in the case of a block having a thickness of 9 mm in the pressing direction Dp by the pressing means, 2 to 4 is appropriate from the viewpoint of the spring force of the pressing means.

  In the method (2), since a relatively rapid cooling and solidification occurs when a block portion having any hardness is produced, cracking is likely to occur due to shrinkage. From the viewpoint of preventing such cracks, in the method (2), it is more effective to use a fatty acid compound having a low melting point or / and an alcohol as described above. Thereby, the block part without a crack can be manufactured with a high yield.

In the method (2), the predetermined order when the block portions are stacked is an order that achieves a hardness gradient that increases the hardness in the stacking direction or in the opposite direction.
In the method (2), as long as such a hardness gradient is achieved, the block obtained by the method (1) may be used as the block portion. When the block obtained by the method (1) is used as the block part of the method (2), the obtained block has a continuous hardness gradient in a part and a graded hardness gradient in another part.

  The term “integration” is used with a concept that a block in which a plurality of block portions are stacked is combined into one unit that can be handled as one use / handling unit. Such integration can usually be achieved by melting the outermost surface of at least one of the lamination surfaces by heating, and then laminating and cooling.

  In another embodiment of the block 70, the block 70 has a hardness gradient that increases the hardness in the pressing direction Dp, as described above, and as shown in FIG. 70a) has a soft lubricant layer 75 that promotes the initial consumption of the block. When the lubricant is supplied to the image carrier through the application member, the application member does not hold the lubricant in the initial stage, so that it is difficult to supply the lubricant smoothly, but a block having such a soft lubricant layer is not provided. If used, the lubricant in the layer is soft and easily consumed, so that the lubricant is effectively supplied from the beginning. Such a soft lubricant layer 75 can be manufactured as a block part by the same method as the above method (2) except that the fatty acid compound and the crystal nucleus content are selected as desired so as to have a predetermined hardness. The obtained soft lubricant layer 75 may be laminated and integrated on the surface 70a of the block 70 by melting and cooling.

The soft lubricant layer 75 usually has a pencil hardness of 2B to 5B, particularly 3B or 4B. The hardness of the soft lubricant layer is not considered when considering the hardness gradient in the pressing direction Dp and the minimum hardness thereof.
The thickness of the soft lubricant layer 75 is usually 1 to 3 mm, particularly 2 to 2.5 mm.

  In another embodiment of the block 70, it is preferable that the block 70 not only has a hardness gradient that increases the hardness in the pressing direction Dp, but also has a hardness gradient in the axial (longitudinal) direction. The hardness gradient in the axis (longitudinal) direction of the block 70 will be described in detail with reference to FIG. FIG. 7 is a schematic top plan view of the block 70 and the application member 72. As shown in FIG. 7, the hardness gradient in the axis (longitudinal) direction of the block 70 means that the hardness of the central portion 70c of the block 70 is the both end portions (70d, 70e) in the axial (longitudinal) direction Dax of the application member 72. With respect to the maximum hardness in the pressing direction Dp in each block portion when the block 70 is divided substantially perpendicularly to the axial (longitudinal) direction Dax, the hardness of the central portion is higher than that of both end portions. Should be high. Preferably, the hardness of the central portion is higher than that of both end portions, even for the minimum height in the pressing direction Dp.

  In recent years, with the progress of miniaturization of image forming apparatuses, there is an increasing need for miniaturization of the solid lubricant block coating mechanism. In that case, it is essential to reduce the diameter of the application member (for example, a brush). At that time, if the diameter of the coating member or its shaft is reduced, bending of the shaft during rotation of the coating member becomes a problem. Specifically, since the coating member 72 is fixed by the bearings 76 at both ends of the shaft 72a, the central portion of the coating member 72 is convex with respect to the image carrier and the block 70 during the rotation because of the bending P. To make contact. For this reason, there is a problem that the central portion of the block is scraped more than both end portions, and the lubricant cannot be supplied and applied uniformly in the axial direction Dax. In the present embodiment, the block 70 is provided with a hardness gradient such that the hardness of the central portion 70c is higher than both end portions (70d, 70e), and the supply amount of the central portion is suppressed, so that the solid in the axial direction Dax is Eliminates uneven wear of lubricant and achieves uniform supply and application of lubricant in the same direction.

The maximum hardness at both ends and the maximum hardness at the center are such that the difference between them is 1 rank or more, especially 1 rank to 3 ranks in pencil hardness, from the viewpoint of more effectively achieving uniform supply in the axial direction Dax. Hardness is preferred. The difference between the minimum hardness at both ends and the minimum hardness at the center is preferably in the same range as the difference in maximum hardness. Specific examples of the highest hardness-minimum altitude pencil hardness combination at the center and both ends are shown below:
Maximum hardness-minimum hardness (B1) central portion; HF, both end portions; HB-B;
(B2) Central part; H-HB, both ends; HB-B;
(B3) Central part; H-HB, both ends; B-2B;
(B4) Central part; F-HB, both ends; B-2B;
(B5) Central part; FB, both ends; B-2B;
(B6) Central part; FB, both ends; 2B-3B;
(B7) Central part; HB-B, both ends; 2B-3B;
(B8) Central part; HB-2B, both ends; 2B-3B;
(B9) Central part; HB-2B, both ends; 3B-4B;
(B10) Central part; B-2B, both ends; 3B-4B;
(B11) Central part; F-2B, both ends; B-3B.

  In FIG. 7, the block 70 has a configuration in which the block 70 is divided into a central portion 70 c and both end portions (70 d, 70 e) in the axial direction Dax, but the maximum hardness at the center portion is higher than the maximum hardness at both end portions. As long as it has a certain hardness gradient, it may have a structure divided into a larger number.

  Also in this embodiment, the block 70 may have the soft lubricant layer as described above on the surface on the image carrier (photosensitive member 1) side (70a).

  In any of the above-described embodiments, the initial shape of the block 70 is not particularly limited. In particular, the surface on the image carrier (photoreceptor 1) side (70a) has, for example, a planar shape, or the shape of the coating member. It may have a concave shape that is recessed along. In particular, when the surface on the image carrier (photoconductor 1) side (70a) has a planar shape, the contact area with the coating member is limited, and thus the surface has the above-described soft lubricant layer. It is valid.

  The pressing means 71 is not particularly limited as long as the block 70 can be pressed in the direction of the image carrier, and usually a spring, a solenoid (magnet), or the like is used.

The application member 72 is not particularly limited as long as it is a rotatable member. For example, the application member 72 may be a brush as shown in FIG. 1 or the like, or may be a roller or a resin sleeve.
Further, the rotation direction of the coating member 72 may be the same direction in the contact area with the image carrier or may be the reverse direction, but is the same direction from the viewpoint of preventing film abrasion of the photoreceptor. It is preferable.

When a brush is used as the application member, the material, length, diameter, density, and the like of the flocked hair (fiber) are not particularly limited, and any brush can be used. In particular, when the image bearing member is a photoconductor whose main raw material is polycarbonate and the hair material is nylon, the length L (mm) of the hair from the viewpoint of more effectively preventing film abrasion of the photoconductor. , Diameter D (μm), density M (KF) (K filament)
M · D ⁴ / L ³ ≦ 7 × 10 ⁶
It is preferable to use a brush that satisfies the above.

An example of the drive mechanism when the block 70 is used and consumed will be described with reference to FIG. FIG. 8 shows a top plan view of the lubricant supply device 7 shown in FIG.
The block 70 is affixed to a sheet metal 81, and a guide 82 is attached to the sheet metal 81 at the end. The guide has a hole and is inserted into the rail 83. A pressing means 71 is provided on the opposite surface of the sheet metal 81 and presses the block 70 in the direction of the image carrier 1 (in the direction of the coating member 72). Since such pressing continues, even if the block 70 is consumed on the contact surface with the coating member 72, the block 70 moves in the direction of the image carrier 1 with the consumption, and the block 70 and the coating member Contact with 72 is ensured. Therefore, in the present invention, the block 70 has a hardness gradient that increases in hardness in the pressing direction Dp, and the hardness of the surface on the image carrier side is relatively high in the initial use, and the hardness decreases with consumption. Even if the pressing force of the pressing means 71 is reduced, the pressure is effectively supplied, and a decrease in the lubricant supply amount can be suppressed.

  In the above description, for example, in the image forming apparatus of FIG. 1 and the like, the case where the photosensitive member is used as the image carrier to which the lubricant is supplied is described. However, the present invention is not limited to this. The solid lubricant block of the present invention can also be applied when supplying a lubricant to an intermediate transfer member such as a belt or an intermediate transfer drum.

<Experimental example 1>
Example 1
A block 1A (9 mm × 9 mm × 330 mm) was manufactured using the mold shown in FIG.
Zinc stearate powder (melting point 125 ° C.) was melted at 170 ° C. and poured into a mold preheated to 170 ° C. The mold is alternately provided with temperature control devices 20 and 21 using refrigerant. The mold surface 30 was controlled to 90 ° C. and the mold surface 31 was controlled to 120 ° C. by the temperature adjusting device, and held in that state for 30 minutes (cooling step 1). Thereafter, the entire mold was cooled to 50 ° C. or less over 60 minutes while maintaining the temperature gradient of the mold surface. Specifically, the mold surface 30 is controlled to 70 ° C., the mold surface 31 is controlled to 100 ° C., and maintained in that state for 30 minutes (cooling step 2), and the mold surface 30 is further set to 50 ° C. Controlled and held in that state for 30 minutes (cooling step 3). Thereafter, the mold was left to cool at room temperature, and the entire mold was adjusted to 50 ° C. or lower.
When the obtained block 1A was taken out and the pencil hardness was measured, the surface in contact with the mold surface 30 had a hardness of 2B, and the surface in contact with the mold surface 31 had a hardness of F.

(Comparative Example 1)
Block 1B was manufactured by the method similar to Example 1 except controlling the temperature of the die surface 30 to the same temperature as the die surface 31 in the cooling steps 1 to 3.
When the obtained block 1B was taken out and the pencil hardness was measured, both the surface that was in contact with the mold surface 30 and the surface that was in contact with the mold surface 31 had a hardness of HB.

(Example 2)
Block 2A (9 mm × 9 mm × 330 mm) was manufactured using the mold shown in FIG.
・ Block part 2A-1
A mixture of 5 parts by weight of barium stearate powder (melting point 225 ° C.) and 95 parts by weight of zinc stearate powder (melting point 125 ° C.) is heated and melted at 170 ° C., poured into a mold preheated to 170 ° C. and naturally cooled. , Solidified.
When the obtained block 2A-1 (3 mm × 9 mm × 330 mm) was taken out and the pencil hardness was measured, all surfaces had a hardness of B.

・ Block part 2A-2
Block part 2A was produced by the same production method as block part 2A-1, except that a mixture comprising 10 parts by weight of barium stearate powder (melting point 225 ° C.) and 90 parts by weight of zinc stearate powder (melting point 125 ° C.) was used. -2 was produced.
When the obtained block 2A-2 (3 mm × 9 mm × 330 mm) was taken out and the pencil hardness was measured, all surfaces had a hardness of 2B.

・ Block part 2A-3
The block part 2A was produced by the same production method as the block part 2A-1, except that a mixture consisting of 15 parts by weight of barium stearate powder (melting point 225 ° C.) and 85 parts by weight of zinc stearate powder (melting point 125 ° C.) was used. -3 was produced.
When the obtained block 2A-3 (3 mm × 9 mm × 330 mm) was taken out and the pencil hardness was measured, all surfaces had a hardness of 3B.

  The obtained block part was laminated and integrated in the order of the block parts 2A-1, 2A-2, and 2A-3 to produce a block 2A. The integration was performed by melting and cooling the laminated surface.

(Evaluation)
A photocopier (MFP 8050; manufactured by Konica Minolta Co., Ltd.) in which the solid lubricant block for the photoconductor is changed to the block obtained in the above example or comparative example, and the brush as the lubricant application member is changed to the brush shown below. As a result, 100,000 half images were printed (photoconductor travel distance base 5500 km). The blocks of Example 1 and Example 2 were mounted on a copying machine so that the hardness increased in the pressing direction by the pressing means.
Brush specification Material: Nylon Fiber thickness: 26.6 μm / fiber density; 830 KF / hair length; 4 mm / axis; φ6

The film scraping amount (abrasion amount) of the photoconductor was measured and was as follows. The central portion is the center in the photosensitive member axial direction, and both end portions are 70 mm from the end in the photosensitive member axial direction.
Example 1; central part 4 μm, both end parts 4 μm;
Comparative Example 1; central portion 10 μm, both end portions 10 μm;
Example 2: Central part 4 μm, both end parts 4 μm.

The initial image (after printing 100 sheets) and the image at the end of printing end (after printing 100,000 sheets) were visually observed with respect to the cleaning property (through toner).
In Example 1 and Example 2, toner slip-through was not observed in either the initial image or the end-of-printing end image.
In Comparative Example 1, no toner slip was observed in the initial image, but the image at the end of the printing end was disturbed on the entire surface due to minute toner slip.

<Experimental example 2>
(Example 3)
Block 3A (9 mm × 9 mm × 330 mm) was manufactured. The block 3A has a central portion (9 mm × 9 mm × 110 mm) having a hardness gradient of maximum hardness F-minimum hardness 2B, and both end portions (9 mm × 9 mm × 110 mm) having a hardness gradient of maximum hardness B-minimum hardness 3B. It is.

-Both ends The block manufactured in Example 2 was cut into a predetermined size and used.
-Central part The block manufactured in Example 1 was cut out to a predetermined size and used.

  One central part and two both end parts are arranged in the order of both end parts-central part-both end parts so that the surfaces having the highest hardness are aligned on the same surface, and the central part and both end parts are integrated. Block 3A was manufactured. The integration was performed by melting and cooling the contact surface.

(Evaluation)
A half image was formed in the same manner as the evaluation method of Experimental Example 1 except that the brush as the lubricant application member was changed to the brush shown below and the blocks obtained in Example 3 and Comparative Example 1 were used. 100,000 sheets were printed and evaluated. The block of Example 3 was mounted on the copying machine so that the hardness was increased in the pressing direction by the pressing means.
Brush specification Material: Nylon Fiber thickness: 15.3 μm / fiber density; 120 KF / hair length; 1 mm / axis; φ5

The film scraping amount (abrasion amount) at the central portion and both end portions in the axial direction of the photoconductor was measured and was as follows.
Example 3; central part 4 μm, both end parts 4 μm;
Comparative Example 1; center part 10 μm, both end parts 15 μm.

The initial image (after printing 100 sheets) and the image at the end of printing end (after printing 100,000 sheets) were visually observed with respect to the cleaning property (through toner).
In Example 3, toner slip-through was not observed in any of the initial image and the end-of-printing end image.
In Comparative Example 1, both the initial image and the end-of-printing image were disordered on the entire surface due to the minute toner slipping through. In the end-of-printing image, both end portions in the photoreceptor axial direction were particularly disturbed.

  The solid lubricant block of the present invention is useful for an image forming apparatus such as a monochrome / color copying machine, a printer, a FAX, or a composite machine thereof.

1 is a schematic cross-sectional view illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged schematic diagram of a lubricant supply device in the image forming apparatus of FIG. 1. It is a schematic diagram for demonstrating the molecular arrangement | sequence when manufacturing the solid lubricant block of this invention. (A) is a top plan view of an example of a mold capable of producing the solid lubricant block of the present invention, and (B) is a cross-sectional view taken along line AA of (A). It is a schematic diagram for demonstrating an example of the manufacturing method of the solid lubricant block of this invention. It is a schematic sectional drawing of an example of the solid lubricant block of this invention. It is a general | schematic upper surface sketch of the solid lubricant block and application member of another embodiment of this invention. It is a schematic top view for demonstrating an example of a drive mechanism when the solid lubricant block of this invention is used and consumed.

Explanation of symbols

1: photoconductor, 2: charging device, 3: exposure device, 4: developing device, 5: transfer device, 6: fixing device, 7: lubricant supply device, 8: cleaning device, 20:21: temperature adjusting device, 30:31: Mold surface, 50: Mold, 51: Molten fatty acid compound, 52: Crystal nucleus, 70: Solid lubricant block, 71: Pressing means, 72: Lubricant application member, 73: Non-moving wall, 75: Soft lubricant layer, 76: bearing, 81: sheet metal, 82: guide, 83: rail.

Claims (8)

  A solid lubricant block that supplies a lubricant to an image carrier while being pressed by a pressing means, and has a hardness gradient.   2. The solid lubricant block according to claim 1, wherein the solid lubricant block has a hardness gradient that increases hardness in a pressing direction of the pressing means. 3.   The solid lubricant block according to claim 1 or 2, wherein 50% by weight or more of the entire solid lubricant block is composed of a fatty acid compound.   The solid lubricant block according to any one of claims 1 to 3, wherein the solid lubricant block has a hardness gradient in which the hardness is continuously increased in the pressing direction by the pressing means.   The solid lubricant block has a hardness gradient in which the hardness gradually increases in the pressing direction by the pressing means, and a plurality of solid lubricant block portions having different hardnesses are laminated in a predetermined order and integrated. The solid lubricant block according to any one of claims 1 to 3.   In the process of cooling and solidifying the heated and melted fatty acid compound in the mold, a solid hardness is provided by giving a temperature distribution to the mold surface of the mold and controlling the cooling rate. A method for producing a lubricant block.   Solid lubrication characterized in that a plurality of solid lubricant block portions having different hardnesses are manufactured, and the obtained solid lubricant block portions are laminated in a predetermined order and integrated to provide a graded hardness gradient. The manufacturing method of an agent block. An image forming apparatus comprising the solid lubricant block according to claim 1.

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