JP2008046189A - Lubricant application device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus comprising a lubricant application device capable of controlling lubricant application quantity to a proper range even if temperature is changed without using a detection means for temperature or lubricant application quantity. <P>SOLUTION: In the image forming apparatus provided with: an image carrier having an image carrying face; an application means having a cylindrical external diameter and rollably held in a state where a cylindrical external form is contacted with the image carrying face; a lubricant block comprising a lubricant applied to the image carrying face; a pressing means for pressing the lubricant block to the cylindrical external form of the application means; and a lubricant feeding mechanism for feeding the lubricant fed from the lubricant block to the cylindrical external form of the application means from the cylindrical external form of the application means to the image carrying face on the basis of the rotation of the application means, the pressing means is provided with an elastic member comprising a shape memory alloy having an austenitic phase. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a printer, a copying machine, a facsimile, or a multi-function machine having a combination of these functions, and a lubricant coating device used therefor, and in particular, applies a lubricant to an image carrier. In particular, the present invention relates to an image forming apparatus and a lubricant application apparatus in which changes in the amount of lubricant applied due to temperature changes are reduced.

  In an electrophotographic image forming apparatus, a latent image formed on a photosensitive member (electrostatic latent image carrier) is visualized with toner supplied from a developing device, and a toner image is transferred to a transfer belt or the like. To do. The toner remaining on the surface of the photoconductor (image bearing surface) after the transfer is scraped and collected by, for example, a cleaning blade (photoconductor cleaning member) that contacts the photoconductor.

  At this time, if the frictional force between the cleaning blade and the photoconductor is high, the wear of the cleaning blade proceeds rapidly, and the thin film formed from the photoelectric material is also worn and peeled on the surface of the photoconductor. There was a problem that the life of each body was shortened. For this reason, a lubricant application device is installed and a lubricant is applied to the surface of the photoreceptor to reduce the coefficient of friction.

  The lubricant application device comprises a roller-shaped lubricant application means comprising a resin rotating brush, a resin roller, a resin sleeve, or the like installed substantially parallel to the photosensitive roller application, and includes a spring or other elastic body. The lubricant is brought into pressure contact with the means. The applying means rotates to scrape off the lubricant, and the shaved lubricant is carried by the applying means and applied to the surface of the photoreceptor.

  The reason why the resin is used for the application means is to cut off the lubricant satisfactorily. The rigidity of these resins is high at low temperatures, low at high temperatures, and the amount of lubricant cut out is low at high temperatures and high at low temperatures. As a result, there is a problem that the amount of the lubricant applied to the surface of the photoreceptor becomes too low at a high temperature and becomes too high at a low temperature.

  If the amount of lubricant applied to the surface of the photoconductor is excessive, the coefficient of friction on the surface of the photoconductor will be low, but the lubricant will completely cover the surface of the photoconductor and fill in minute irregularities on the surface of the photoconductor. For this reason, the adhesion between the cleaning blade and the surface of the photosensitive member is improved, and metal oxide fine particles externally added to the toner surface, called post-processing agent fine particles, cannot pass through the edge portion of the cleaning blade and the cleaning blade edge portion and the photosensitive member Stay between. As a result, there was a problem that the blade turned up or an abnormal noise called blade crying occurred.

  Therefore, for example, the amount of lubricant on the surface of the photoconductor is measured by a detecting means such as a reflection type photosensor, and the lubricant application device is controlled based on the measured value so that the amount of lubricant on the surface of the photoconductor is within a certain range. Patent Document 1 discloses management.

Also, it is patented to manage the amount of lubricant on the surface of the photoconductor by measuring the temperature of the usage environment using temperature detection means such as a temperature sensor and using that information to control the pressure applied to the lubricant. Documents 2-5.
JP 7-311531 A JP-A-9-62163 JP-A-9-138622 JP 2002-341694 A Japanese Patent Laid-Open No. 2005-3808

  However, in the techniques described in these Patent Documents 1 to 5, a means for detecting the lubricant amount or temperature and a circuit for calculating based on the information obtained from these detection means and generating a control signal are indispensable. In addition, since a new space is required for these installations, there has been a problem in that downsizing of the image forming apparatus is hindered.

  Accordingly, the present invention provides an image forming apparatus having a lubricant application device that can manage the lubricant application amount within an appropriate range even if the temperature changes without using a temperature or lubricant application amount detection means. With the goal.

  The present invention relates to an image carrier having an image bearing surface, a coating means having a cylindrical outer diameter and rotatably held in a state where the cylindrical outer shape is in contact with the image bearing surface, and the image bearing surface is coated. A lubricant block containing a lubricant, a pressing means for pressing the lubricant block toward the cylindrical outer shape of the applying means, and a lubricant supplied from the lubricant block to the cylindrical outer shape of the applying means based on the rotation of the applying means. In the image forming apparatus including the lubricant supply mechanism for supplying the image bearing surface from the cylindrical outer shape of the coating unit, the pressing unit includes an elastic member including a shape memory alloy having an austenite phase. An image forming apparatus.

  In the image forming apparatus according to the present invention, the lubricant application amount on the surface of the photoreceptor is kept within a certain range regardless of the temperature change by the lubricant application device having a simple configuration without using the means for detecting the temperature or the lubricant application amount. It becomes possible to maintain.

Embodiment 1
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, terms indicating a specific direction and position (for example, “up”, “down”, “right”, “left” and other terms including those terms) are used as necessary. These terms are used to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Moreover, the part of the same code | symbol which appears in several drawing shows the same part or member.

  FIG. 1 is a top view of a lubricant application device represented as a whole by 6 according to the present invention, and FIG. 2 is a cross-sectional view of FIG. 1 viewed in the II-II direction. The lubricant application device 6 includes a fixed plate 61 installed in the vicinity of the photoreceptor 4 (only a part of which is shown in FIGS. 1 and 2) inside the image forming apparatus. One end of a spring 62 made of an elastic member, specifically, a shape memory alloy is fixed to the fixing plate 61. The other end of the spring 62 is attached to the lubricant holder 63, and the spring 62 functions as a pressing means. The lubricant holder 63 holds a lubricant block 64 whose main component is a lubricant. As can be seen from FIG. 1, there are openings 67 at both ends of the lubricant holder 63, through which guides 66 (not shown in FIG. 2) pass, and the lubricant block (lubricant) 64 can move left and right. It has become. The spring 62 is a so-called compression spring, and presses the lubricant block 64 against the application means 65 through the lubricant holder 63.

  The application means 65 may use a resin roller having a cylindrical outer shape (cylindrical outer shape) or a resin sleeve in order to scrape the lubricant 64 stably. More preferably, the application means 65 is made of resin having a cylindrical outer shape. A rotating brush 65 is used. The rotating brush 65 has a central shaft 651 connected to a drive system including a motor (not shown), and applies the lubricant 64 scraped by the rotating brush bristles 653 to the surface (image carrying surface) of the photoreceptor 4.

In a preferred example of the rotating brush 65, the length in the major axis direction (FIG. 1, the length in the Y direction) is 340 mm, and the lubricant can be applied to the entire image area described later of the photosensitive member 4. The cross section has a diameter of 18 mm and the central axis 651 has a diameter of 6 mm. The flocked portion (brush portion) 653 is made of nylon, the hair length is 5 mm, the fiber diameter is 26.6 μm, and the fiber density is 600 KF / inch ² (600,000 F / inch ² ) in a base fabric 652 having a thickness of 1 mm. Has been. In the present invention, other rotating brushes can be used. For example, the material may be other resin such as polypropylene, and the spring constant and lubrication of the shape alloy spring 62 using the direct line, the length of the hair, the fiber diameter, etc. It can be appropriately selected depending on the type of agent.

  The optimum range of the coefficient of friction was investigated. Specifically, using a portable contact angle meter HEIDON Tripocures TYPE 94iII manufactured by Shinto Kagaku Co., Ltd. and using cotton flannel as a probe, the friction coefficient of the surface of the photoconductor is measured by changing the amount of lubricant applied. did. As a result, there is no abnormal wear of the cleaning blade due to an excessive friction coefficient, abrasion or peeling of the thin film on the surface of the photoreceptor, and no problems such as blade turning or blade crying that occur when the friction coefficient is too small. For this purpose, it has been found that the static friction coefficient is desirably in the range of 0.3 to 0.5, more desirably 0.35 to 0.45.

  The lubricant used is a solid lubricant made of zinc stearate. However, in the present invention, in addition to this, it has good wettability with the photoconductor, is chemically inert, and is thermally stable. Any lubricant can be used. More preferably, a lubricant having a low surface energy and excellent in toner releasability during transfer is preferable. As such a lubricant, for example, one or more components selected from fatty acids such as stearic acid, palmitic acid, and lauric acid, and fatty acid metal salts that are compounds of these fatty acids and metals such as calcium, zinc, and magnesium are mainly used. A solid lubricant having a small component can be used.

  The photoreceptor 4 has an image area width L1 (FIG. 1) of 330 mm and a diameter of 60 mm. In order to keep the coefficient of static friction of the surface of the photoconductor 4 at 0.4, it was found that a 2 g lubricant application amount is necessary at a distance of 10 km on the surface of the photoconductor.

  Next, the relationship between the amount of lubricant applied and the pressing force is shown. FIG. 3 shows that the number of pressing springs 62 of the coating device 6 is changed to change the pressing force from 0.4 N / m to 4.0 N / m and the temperature (the temperature in the image forming apparatus) from 0 ° C. to 50 ° C. The results of the measurement of the amount of lubricant applied to the surface of the photoconductor (per distance of 10 km on the surface of the photoconductor). FIG. 4 shows the relationship between the amount of lubricant applied to the surface of the photoreceptor (per 10 km distance on the surface of the photoreceptor) and temperature.

  In any pressing force, the lubricant application amount increases as the temperature decreases. This is because, as described above, the rigidity of the bristles of the rotary brush 65 is higher as the temperature is lower, and as a result, the amount of lubricant that is scraped off from the surface of the lubricant 64 increases.

  At any temperature, the pressure increases up to 2.4 N / m and the amount of applied lubricant increases, but when the pressure exceeds 2.4 N / m, the pressure increases. At the same time, the amount of lubricant applied has decreased.

  This is because if the pressing force is too strong, the bristles of the rotating brush 65 are excessively curved, the side surfaces of the bristles come into contact with the lubricant, and the bristle tip having a high ability to scrape off the lubricant does not come into contact with the lubricant. This is because a “belly hit” occurs.

  As shown in FIG. 3, for the distance of 10 km on the surface of the photoconductor, there is no occurrence of bumping and a coating amount of 2 g of lubricant is 0.45 N / m at 0 ° C., 0.7 N / m at 10 ° C., 23 1.2N / m at 30 ° C, 1.6N / m at 30 ° C, 1.75N / m at 40 ° C, and N / m at 50 ° C. Show.

  In the present embodiment, a shape memory alloy spring is used as the pressing spring 62 as means for changing the pressing force according to the temperature. The mechanism is shown below.

  Two effects are known for shape memory alloys. One is the shape memory effect using the martensite phase that appears at low temperatures. It easily deforms when stress is applied to the martensite phase at low temperatures, and remains deformed even when the stress is removed. When the temperature rises and the martensite phase transforms to the austenite phase at a high temperature, it returns to its original shape.

  The other is a superelastic effect using an austenite phase. When stress is applied, the austenite phase starts elastic deformation, and when the stress value further increases, the austenite phase undergoes stress-induced transformation into a martensite phase. When the stress is unloaded, the original austenite phase is restored, and the elastic deformation of the austenite phase is also eliminated, whereby the shape is restored.

  As will be described in detail below, the present invention uses the property that the ratio of the martensite phase showing the shape memory effect and the austenite phase showing the superelastic effect changes with temperature, and changes the pressing force.

  The temperature at which transformation starts from the martensite phase to the austenite phase by changing the composition of the shape memory alloy and the heat treatment conditions, particularly the quenching rate (hereinafter referred to as “austenite transformation start temperature”) and the temperature at which transformation ends (hereinafter referred to as “austenite” By changing the transformation end temperature "), it is possible to adjust which effect is obtained at a desired temperature.

  In the shape memory alloy used for the spring 62, the austenite transformation start temperature is lower than the use temperature (the temperature in the image forming apparatus), and the austenite transformation end temperature is higher than the use temperature. In other words, at the operating temperature, the shape memory alloy used for the spring 62 has two phases of martensite phase and austenite phase. When a displacement is applied to the spring 62, the martensite phase portion exhibits a shape memory effect, so the spring does not exhibit a force to return to its original state (restoring force), and is deformed according to the amount of displacement. Does not contribute to pressure generation. On the other hand, the austenite phase exhibits a restoring force, that is, generates a pressing force.

  As the operating temperature rises, the proportion of martensite phase decreases and the proportion of austenite phase increases, so the pressing force increases even with the same amount of displacement. FIG. 5 shows the relationship between the temperature and the pressure of the spring 62 made of a Ti—Ni alloy (Ni 50.1 atomic%). The spring displacement is constant at 4 mm. The pressing force increases as the temperature increases, and the value of the pressing force at each temperature is substantially equal to the desired pressing force described above. When the temperature exceeds 50 ° C., the pressing force is substantially constant. This is because the austenite transformation end temperature of the shape memory alloy used for the spring 62 is about 50 ° C. This is because there is no increase in the pressing force. As described above, when the pressing force exceeds 2.4 N / m, the amount of lubricant applied decreases due to the occurrence of contact with the belly. Therefore, the austenite transformation completion temperature is preferably 50 ° C. to 60 ° C., thereby 60 ° C. or more. In this case, the pressing force is not increased and no hitting occurs. On the other hand, the austenite transformation start temperature is preferably 0 ° C. or lower in consideration of the use environment of the apparatus.

  As described above, as a shape memory alloy capable of increasing the pressing force with the temperature with constant displacement by setting the austenite transformation start temperature to 0 ° C. or less and the austenite transformation end temperature to 50 to 60 ° C., Cu Alloy systems such as -Zn-Al alloys are known. However, as a shape memory alloy having durability that can be repeatedly used in the image forming apparatus, the above-described Ti—Ni alloy (Ni 40 to 55 atomic%, the balance is Ti and inevitable impurities) or Ti—Ni alloy is Cu, Fe. An alloy to which a total of less than 10 atomic% of one or more additive elements such as Al is added is suitable.

  FIG. 6 shows the relationship between temperature and lubricant application amount. In the temperature range of 0 to 60 ° C., the amount of lubricant applied is substantially constant at 2 g per 10 km of the distance on the surface of the photoreceptor, whereby the friction coefficient can be made substantially constant (0.4).

  In the embodiment shown in FIGS. 1 and 2, the elastic member used for the pressing means 62 is a spring made of a shape memory alloy. However, by appropriately selecting a variable related to the pressing force such as a spring constant, Among the plurality of springs constituting the means 62, only a part is made of a spring made of a shape memory alloy, and the rest is made of a spring made of a metal other than the shape memory alloy, or an elastic compression deformation means other than the spring, such as rubber. An elastic material may be used.

  FIG. 7 shows a schematic configuration of an image forming apparatus according to an embodiment of the present invention, the whole of which is represented by 2. However, the housing of the image forming apparatus is omitted from the drawing in order to clarify the features of the present invention and to facilitate understanding of the invention.

  The image forming apparatus 2 is an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multi-function machine having a combination of these functions. The illustrated image forming apparatus is a so-called tandem color image forming apparatus. However, the present invention is not applied only to this type of image forming apparatus, and other types of image forming apparatuses, for example, four developing devices are arranged around a rotating shaft, and these are electrostatically connected sequentially. The present invention can be similarly applied to a so-called four-cycle image forming apparatus that creates a full-color image facing a latent image carrier, or a monochrome image forming apparatus having only one developing device.

  Yellow (Y), magenta (M), cyan (C), black (in order from the right side to the left side in the figure) are placed on the belt portion that moves from the roller 32 on the right side in the figure to the roller 34 on the left side in the figure. Four image forming units 3 (3Y, 3M, 3C, and 3K) that respectively create toner images of corresponding colors using the developer K) are arranged along the intermediate transfer belt 30.

  Each image forming unit 3 includes a cylindrical photosensitive member 4 as an electrostatic latent image carrier. Around the photoconductor 4, there are a charger 8, an exposure device 10, a developing device 18, a primary transfer roller 14, a lubricant application device 6, and a cleaning blade 16 in that order along the rotation direction (clockwise direction in the drawing). The primary transfer roller 14 is disposed inside the endless intermediate transfer belt 30.

  An example of an image forming operation in the color mode will be briefly described. First, in each image forming unit 3, the outer peripheral surface (image carrying surface) of the photoreceptor 4 that is rotationally driven at a predetermined peripheral speed is coated with a lubricant by the lubricant coating device 6 and remains with the cleaning blade 16. After the toner is removed, it is charged by the charger 8. In the embodiment, a plate-like blade is used as the photosensitive member cleaning blade 16, and one end side thereof is in contact with the outer peripheral surface of the photosensitive member 4. Next, light corresponding to the image information is projected from the exposure device 10 on the outer peripheral surface of the charged photoconductor 4 to form an electrostatic latent image. Subsequently, the electrostatic latent image is made visible by the developer toner supplied from the developing device 18. When the toner image of each color formed on the photoconductor 4 in this way reaches the primary transfer region by the rotation of the photoconductor 4, yellow, magenta, cyan, and black are sequentially transferred from the photoconductor 4 to the intermediate transfer belt 30. Transferred (primary transfer) and overlaid.

  The toner remaining on the photosensitive member 4 without being transferred to the intermediate transfer belt 30 is scraped off by the cleaning blade 16 when reaching the contact portion between the photosensitive member 4 and the cleaning blade 16, and the outer periphery of the photosensitive member 4. Removed from the surface.

  The superimposed four color toner images are conveyed to the secondary transfer region 41 by the intermediate transfer belt 30. On the other hand, the paper accommodated in the paper feed cassette 44 is conveyed to the secondary transfer area 41 in accordance with the timing. Then, the four color toner images are secondarily transferred from the intermediate transfer belt 30 to the paper in the secondary transfer region 41. The paper on which the four color toner images have been transferred is transported further downstream in the transport path 50, and the toner image is fixed on the paper by the fixing roller 54, and then sent to the paper discharge unit 58 by the paper discharge roller 56. The intermediate transfer belt 30 that has passed through the secondary transfer region 41 is cleaned by the cleaning member 42. Thereafter, the rotational drive of each photoreceptor 4 and the intermediate transfer belt 30 is stopped.

  The lubricant application device 6 according to the present invention is not limited to the photosensitive member 4 (electrostatic latent image carrier) in the above-described image forming apparatus, but may be another image carrier such as the transfer belt 30 or the like as required. In the embodiment shown in FIG. 7, although not used, the present invention can be applied to a transfer drum to which a toner image is transferred or a transfer means corresponding thereto. In addition, the image forming apparatus including the transfer belt, the transfer drum, and the corresponding product to which the lubricant device 6 according to the present invention is applied is naturally included in the scope of the present invention.

Embodiment 2
FIG. 8 is a sectional view seen from the same direction as FIG. 2 showing a lubricant application apparatus according to another embodiment of the present invention, indicated as a whole by 600. In the lubricant 164, the area of the cross section perpendicular to the direction in which the pressure is applied (the cross section perpendicular to the X direction in the drawing) gradually increases from the portion in contact with the rotating brush 65 toward the shape memory alloy spring 62. Yes. When the lubricant 164 is scraped off by the rotating brush 65 and the thickness (the length in the X direction in FIG. 8) is reduced, the displacement of the spring 62 is also reduced, and the pressing force is reduced. The lubricant 164 has a shape that can increase the contact area between the rotary brush 65 and the lubricant 164 with a decrease in displacement for the purpose of preventing a decrease in the amount of lubricant applied accompanying this.

  In FIG. 8, the shape of the cross section of the lubricant 164 parallel to the paper surface is a trapezoid, but is not limited to this. Various cross-sectional shapes in which the cross-sectional area of the surface perpendicular to the X axis in FIG. 8 gradually increases from the portion in contact with the application unit 65 toward the pressing unit 62. There is a shape in which at least one of the upper and lower sides is a convex or concave curved surface.

  8 other than the lubricant 164, that is, the fixed plate 61, the shape memory alloy spring 62, the lubricant holder 63, the rotating brush 65, and the guide 66 (not shown) are the same as those in FIG.

It is a top view of the lubricant application device concerning the present invention. 1 is a cross-sectional view of a lubricant application device according to the present invention. It is a graph which shows the relationship between lubricant application amount and pressing force. It is a graph which shows the relationship between lubricant application amount and temperature. It is a graph which shows the relationship between pressing force and temperature. It is a graph which shows the relationship between lubricant application amount and temperature. 1 is a side view of an image forming apparatus according to the present invention. 1 is a cross-sectional view of a lubricant application device according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 4 Photosensitive body (electrostatic latent image carrier), 6 Lubricant coating device, 61 Fixed plate, 62 Pressing spring (pressing means), 63 Lubricant holder, 64 Lubricant block (lubricant), 65 Rotating brush (Coating means) ), 66 guide, 67 Lubricant holder opening, 651 rotating brush central axis, 653 rotating brush flocking part (brush part)

Claims (10)

An image carrier having an image bearing surface;
Coating means having a cylindrical outer diameter and rotatably held in a state in which the cylindrical outer shape is in contact with the image bearing surface;
A lubricant block containing a lubricant applied to the image bearing surface;
Pressing means for pressing the lubricant block toward the cylindrical outer shape of the application means;
A lubricant supply mechanism for supplying the lubricant supplied from the lubricant block to the cylindrical outer shape of the coating means based on the rotation of the coating means from the cylindrical outer shape of the coating means to the image carrying surface; In an image forming apparatus comprising:
The image forming apparatus, wherein the pressing means includes an elastic member including a shape memory alloy having an austenite phase.   The shape memory alloy contains 40 atomic% to 55 atomic% of Ni and the balance is a Ni—Ti alloy composed of Ti and inevitable impurities, or contains 40 atomic% to 55 atomic% of Ni and the balance is less than 10 atomic%. The image forming apparatus according to claim 1, wherein the image forming apparatus is a Ni—Ti alloy composed of the above elements and inevitable impurities.   3. The image forming apparatus according to claim 1, wherein the shape memory alloy has an austenite transformation start temperature of 0 ° C. or less and an austenite transformation end temperature of 50 ° C. to 60 ° C. 4.   The image formation according to claim 1, wherein an area of a cross section perpendicular to the pressing direction of the lubricant gradually increases from a portion in contact with the coating unit toward the pressing unit. apparatus.   The image forming apparatus according to claim 1, wherein the lubricant is a solid lubricant containing a fatty acid, a fatty acid metal salt, or both. A lubricant application device installed in an image forming apparatus,
A coating means having a cylindrical outer shape and rotatably held in a state where the cylindrical outer shape is in contact with an image bearing surface of an image carrier disposed in the image forming apparatus and outside the lubricant coating device;
A lubricant block containing a lubricant applied to the image bearing surface;
Pressing means for pressing the lubricant block toward the cylindrical outer shape of the application means;
A lubricant supply mechanism for supplying the lubricant supplied from the lubricant block to the cylindrical outer shape of the coating means based on the rotation of the coating means from the cylindrical outer shape of the coating means to the image bearing surface; In a lubricant application device comprising:
The lubricant applying apparatus, wherein the pressing means includes an elastic member including a shape memory alloy having an austenite phase.   The shape memory alloy contains 40 atomic% to 55 atomic% of Ni and the balance is a Ni—Ti alloy composed of Ti and inevitable impurities, or contains 40 atomic% to 55 atomic% of Ni and the balance is less than 10 atomic%. The lubricant application device according to claim 6, wherein the lubricant application device is a Ni—Ti alloy composed of the above elements and inevitable impurities.   The lubricant application apparatus according to claim 6 or 7, wherein the shape memory alloy has an austenite transformation start temperature of 0 ° C or lower and an austenite transformation end temperature of 50 ° C to 60 ° C.   The lubrication according to any one of claims 6 to 8, wherein an area of a cross section perpendicular to the pressing direction of the lubricant gradually increases from a portion in contact with the coating unit toward the pressing unit. Agent applicator. The lubricant application device according to any one of claims 6 to 9, wherein the lubricant is a solid lubricant containing a fatty acid or a fatty acid metal salt, or both.

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