Method for testing the flammability of a grease composition, grease composition, bearing, and gear

Abstract

This invention provides a method for evaluating the non-flammability of a grease composition in a combustion test that closely resembles the environment in which it is used. [Solution] A combustion test method for a grease composition 10 containing a base oil and a thickener, wherein the grease composition 10 to be evaluated is placed in a container 1 with an open top, a heat source is introduced into the grease composition 10 from above to ignite it, and the container 1 is equipped with a liquid guide mechanism that guides the liquid component of the grease composition 10, which has become liquid due to the heat, away from the introduced heat source. The liquid guide mechanism is, for example, composed of an opening 3A provided in the container 1.

Description

Technical Field

[0001] The present invention relates to a flame-retardant grease composition characterized by non-flammability and the evaluation of its flame retardancy. Further, the present invention relates to bearings and gears formed by enclosing the above-mentioned flame-retardant grease composition characterized by non-flammability. The present invention is a technology suitable for bearings, gears, etc. used in high-temperature environments such as steelmaking facilities and forging facilities.

Background Art

[0002] For example, for lubricating the bearings of equipment used in high-temperature environments such as steelmaking facilities and forging facilities, lubrication by a large-scale centralized greasing method using a grease composition is performed. However, there is a risk that the used grease composition may drip and accumulate under the equipment, and the accumulated grease composition may be exposed to high temperatures. Also, when high-temperature scale scatters onto the grease composition, there is a risk of ignition of the grease composition. To solve this problem, the used grease composition is manually removed. However, it is difficult to remove the grease composition that has dripped and accumulated in narrow places where it is difficult for people to enter. Also, if ignition is detected immediately, extinguishing the fire is easy, but in recently automated equipment, there are few workers, and ignition is not always detected immediately. If the detection of ignition is delayed, extinguishing the fire may become difficult or even impossible. Therefore, there is a demand for a grease composition that is excellent in flame retardancy and difficult to ignite even when the accumulated grease composition is exposed to high temperatures or when high-temperature scale scatters.

[0003] As a conventional method for evaluating the non-flammability (flame retardancy) of such a flame-retardant grease composition, a ointment can combustion test has been proposed (see Patent Document 1). As shown in FIG. 9, in the ointment can combustion test, a container 20 surrounded on all sides is filled with a grease composition 10. An iron ball 21 heated by an electric furnace or the like is introduced as a heat source into the filled grease composition 10 to ignite (set fire to) the grease composition 10. Then, the non-flammability is evaluated from the extinguishing time (combustion time) until the ignition self-extinguishes.

[0004] Furthermore, Patent Document 2 proposes a grease composition that contains water in order to ensure flame retardancy so that combustion does not occur even at high temperatures. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 4268789 [Patent Document 2] Patent No. 6899788 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In ointment can combustion tests, the grease composition melts due to heat. According to the inventors' research, the grease composition, once melted and liquid, has high cooling efficiency relative to the heat source. Therefore, it was found that in ointment can combustion tests, the liquid grease composition remains around the heat source inside the container, resulting in less accurate evaluation of the flame retardancy (non-flammability) of the grease composition.

[0007] Furthermore, as described in Patent Document 2, when prioritizing flame retardancy and adding water to the grease composition, the stability of the grease composition is low in high-temperature environments exceeding 100°C. In addition, there is a risk that the flame retardancy will be lost as the water dissipates over a long period of time, and that the water will turn into water vapor, causing the pressure inside the pipe to increase.

[0008] This invention has been made in view of the points mentioned above, and one of its objectives is to provide a method for evaluating the non-flammability (flame retardancy) of a grease composition in a combustion test that closely resembles the usage environment of the grease composition. Another objective of this invention is to provide a grease composition that exhibits excellent non-flammability in this evaluation. [Means for solving the problem]

[0009] To solve the problem, one aspect of the present invention is a method for testing the combustion of a grease composition, wherein the grease composition to be evaluated is placed in a container with an open top, a heat source is introduced into the placed grease composition from above to ignite it, and the container guides the liquid component of the placed grease composition, which has become liquid due to the heat, away from the introduced heat source.

[0010] Furthermore, another aspect of the present invention is a grease composition comprising a base oil and a thickener, wherein the thickener has a metal soap group, and the mixing ratio of calcium 12-hydroxystearate and lithium 12-hydroxystearate is in the range of 9:1 to 6:4 in molar ratio, and which has flame retardancy such that it self-extinguishes within 3 minutes after being ignited using a heat source of 950°C in the combustion test method of the grease composition described in one aspect of the present invention. [Effects of the Invention]

[0011] According to the combustion test method for grease compositions in an embodiment of the present invention, the flame retardancy performance of the grease composition can be appropriately evaluated by conducting a combustion test that closely resembles the environment in which the grease composition is used.

[0012] Furthermore, according to aspects of the present invention, it is possible to provide a flame-retardant grease composition that has been appropriately evaluated. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows an example of a container for combustion testing according to an embodiment of the present invention. [Figure 2] This figure shows an example of a container for combustion testing according to an embodiment of the present invention. [Figure 3] This figure shows an example of a container for combustion testing according to an embodiment of the present invention. [Figure 4] This figure shows an example of a container for combustion testing according to an embodiment of the present invention. [Figure 5] This figure shows an example of results obtained using a conventional combustion test method. [Figure 6] It is a diagram showing an example of the ignition start temperature in a combination of grease compositions. [Figure 7] It is a diagram showing an example of the results by the combustion test method according to an embodiment based on the present invention. [Figure 8] It is a diagram for investigating the ignition start temperature. [Figure 9] It is a diagram for explaining a conventional combustion test method. [Figure 10] It is a diagram schematically showing the state in which the grease composition in the conventional combustion test method becomes liquid.

Embodiments for Carrying Out the Invention

[0014] Next, embodiments of the present invention will be described with reference to the drawings. "Combustion Test Method for Grease Composition" The combustion test method of this embodiment enables more accurate evaluation of the flame retardancy of the grease composition by a new grease combustion test. The procedure of the combustion test method of this embodiment is basically the same as the conventional one.

[0015] Here, the inventors obtained the following findings. That is, in the evaluation of grease flame retardancy by the conventional ointment can combustion test, as shown in Fig. 9(a), a combustion container 20 composed of a can with only the upper part open is used. The grease composition 10 to be evaluated is filled so as to fill the lower part of the combustion container 20. Then, as shown in Fig. 9(b), a high-temperature iron ball 21 as a heat source is dropped from above to ignite the grease composition 10. The reference numeral 22 in Fig. 9(b) represents the flame due to ignition. In this combustion test method, the liquid component (liquid) melted by the heat source stays in the container 20 and contacts the heat source 21. The liquid contacting the heat source 21 has a larger contact area with the heat source than the solid. Also, in the container 20, as shown in Fig. 10, convection occurs with the melted grease composition 10. As a result, it was found that in the conventional ointment can combustion test method, the liquid component accumulated in the combustion container 20 quickly releases the heat of the heat source 21.

[0016] Based on these findings, in this embodiment, the container used in the combustion test method is configured to be equipped with a liquid guide mechanism. This liquid guide mechanism is a guide mechanism that guides the liquid, such as grease or base oil, dissolved by the heat source 21, away from the heat source 21 into which it was introduced.

[0017] (Combustion container 1) Next, as examples of the combustion container 1 equipped with a liquid guide mechanism used in this embodiment, configuration examples of the first to third containers are shown. Note that the container of this embodiment may be constructed by combining multiple liquid guide mechanisms described below.

[0018] <First container 1> The first container 1, as shown in Figure 1, has a main body that is open at the top and has a bottom portion 2 and wall portions 3. In this example, a cylindrical container 1 is shown. The container shape may also be such that the wall portions 3 are erected at an angle to the bottom portion 2. Furthermore, the container 1 is not limited to a circular shape when viewed from above, but may also be rectangular or other shapes.

[0019] The first container 1 has one or more openings 3A in at least one of the lower part of the wall portion 3 of the container 1 and the bottom surface. These one or more openings 3A constitute a liquid guide mechanism. In the example in Figure 1, there are multiple (four in Figure 1) slit-shaped openings 3A in the wall portion 3.

[0020] The grease composition 10 contained in container 1 is in a viscous semi-solid state, but when heated by the heat source, a portion of it melts and becomes liquid, and this liquid moves downward due to its own weight. In this embodiment, the dissolved liquid is discharged from the opening 3A.

[0021] Therefore, it is preferable that the height of the opening 3A provided in the wall portion 3 be as low as possible. For example, it is preferable that the lower position of the opening 3A be set to 5 mm or less from the bottom surface of the container 1. Furthermore, it is preferable that the opening 3A provided in the bottom portion 2 of the container 1 be located on the outer circumference.

[0022] Conventionally, as shown in Figure 9, the grease composition 10 is filled so as to cover the entire bottom surface of the container 1. In contrast, in this embodiment, as shown in Figure 1, it is preferable that the grease composition 10 to be contained is placed on the bottom surface of the container 1 without contacting the wall portion 3. In particular, it is preferable that the grease composition 10 is placed at a bottom surface position inside the position of the opening located on the outer circumference of the bottom surface.

[0023] In other words, it is preferable to divide the bottom surface of container 1 into a placement area S on the central side where the grease composition 10 is placed, and a non-placement area T on its outer periphery, and then perform the test. The same applies to any of the following containers 1.

[0024] While it is possible to form the above-mentioned opening in the mounting area S, the opening must have an area large enough to prevent the semi-solid grease composition 10 from entering, and the semi-solid grease composition 10 may prevent the liquid grease composition 10 from moving into the opening. For this reason, it is preferable to provide the opening in a non-mounting area T that does not come into contact with the contained semi-solid grease composition 10.

[0025] The opening area of ​​opening 3A is not particularly limited, but for example, if converted to a circular shape, it would be 200 mm. 2 That would be sufficient. Furthermore, the cross-sectional shape of the opening 3A is not limited to a slit shape, but may consist of holes of a circular or rectangular shape.

[0026] <Second container 1> As shown in Figure 2, the second container 1 is an example in which, in addition to the configuration of the first container 1, a storage section 4 for storing liquid components is provided. The storage section 4 is preferably located in a position where the liquid discharged from the opening 2A can move to the storage section 4 by its own weight. In the second container 1, the liquid grease composition 10 that flows out (is discharged) from the opening 2A can be stored in the storage section 4, making it easy to recover the liquefied grease composition 10.

[0027] The second container 1 shown in Figure 2 has a bottom surface 2 that has a central mounting area S and a non-mounting area T on its outer periphery. In the non-mounting area T, an endless annular opening 2A, such as a ring, is formed when viewed from above, and an annular storage section 4 is positioned below the opening 2A. In this example, an object 5 capable of extinguishing fire, such as a fire extinguishing agent or water, is placed inside the storage section 4. However, it is not necessary to place an object 5 or the like inside the storage section 4. In this example, the height of the surface of the non-mounting area T is lower than that of the surface of the mounting area S.

[0028] Furthermore, the opening area of ​​the endless annular opening 2A and the bottom surface area of ​​the storage section 4 do not necessarily have to be the same when viewed from above. Also, it is preferable that the volume of the storage section 4 is equal to or greater than the volume of the semi-solid grease composition 10 contained in the container 1.

[0029] Furthermore, the opening 2A does not have to be an endless annular opening. For example, the container 1 may have a double bottom, and multiple openings 2A may be formed on the outer circumference of the upper bottom surface. In this case, the storage section 4 is formed by the lower bottom surface and the outer wall portion.

[0030] <Third container 1> The third container 1, as shown in Figure 3, is an example configuration in which the bottom surface of the container 1 comprises a placement area S on which the grease composition 10 is placed, and a non-placement area T located on the outer periphery of the placement area S. The surface of the non-placement area T serves as the liquid component guide surface.

[0031] The third container 1 has a configuration in which the non-placement area T is located below the placement area S. The configuration in which the entire non-placement area T is located below the placement area S in a stepped manner is the same as that of the second container 1.

[0032] In contrast, the third container 1 has a surface shape that is inclined such that the non-placement area T is located lower as it moves away from the placement area S. In this case, the dissolved liquid moves toward the wall portion 3 due to the inclination of the non-placement area T, thereby moving away from the heat source.

[0033] <Fourth container 1> As shown in Figure 4, the fourth container 1 has a bottom surface comprising a placement area S on which the grease composition 10 is placed, and a non-placement area T located on the outer periphery of the placement area S. The non-placement area T serves as a liquid component guide surface.

[0034] In the fourth container 1, for example, the radial width of the non-placement area T is configured to be greater than or equal to the radius of the placement area S. Alternatively, the area of ​​the bottom surface of container 1 is set so that the diameter D, when converted to a circle, is 2.5 times or more the diameter of the iron ball used as a heat source.

[0035] In the fourth container 1, the non-placement area T is made wider than in the other examples, which guides the dissolved liquid away from the heat source. As the liquid moves mainly over the non-placement area T, contact between the heat source and the liquid is suppressed, and the low height of the stored liquid prevents convection of the liquid. While there is no specific upper limit on the radial width of the non-mounted area T, an upper limit is defined from a practical standpoint.

[0036] (Procedure for combustion testing) The combustion test method of this embodiment is carried out as follows. First, as shown in Figure 1, the semi-solid grease composition 10 to be evaluated is placed on the placement area S, which is the central part of the bottom surface of the combustion container 1 of this embodiment.

[0037] Next, a high-temperature iron ball is placed towards the grease composition 10 as a heat source (see Figure 9), and ignition is performed by the heat of the iron ball. The liquid component, melted by the heat from the heat source, moves downward and further towards the non-placement area T. In this example, the mere presence of the non-placement area T causes the liquid component to move away from the heat source.

[0038] Then, in the first container 1, the liquid component dissolved by the heat source passes through the opening 3A and is discharged outside the container 1. As a result, the amount of dissolved grease in contact with the heat source is reduced, and the cooling performance of the heat source becomes slower compared to the conventional method.

[0039] Furthermore, in the second container 1, the liquid component discharged from the opening 2A falls into the storage section 4 and is stored there. Furthermore, in the third container 1, the liquid component dissolved by the heat source moves to the non-placement area T, and then moves further towards the outer periphery (wall 3 side) due to the inclination of the non-placement area T. In other words, the liquid component is guided away from the heat source. As a result, the amount of dissolved grease in contact with the heat source is reduced, and the cooling performance of the heat source becomes slower compared to the conventional method.

[0040] Furthermore, in the fourth container 1, the liquid component dissolved by the heat source moves to the non-placement area T. That is, in the fourth container 1, the liquid component moves onto the non-placement area T and away from the heat source, and the area of ​​the non-placement area T is wider than in the conventional method, so the height of the liquid component stored on the non-placement area T is reduced, and it is possible to suppress the amount of liquid component on the non-placement area T that moves towards the heat source. As a result, the amount of dissolved grease in contact with the heat source is reduced, and the cooling performance of the heat source becomes slower compared to the conventional method.

[0041] In the usage environment of grease composition 10, which is used as a lubricant in bearing devices and the like, it is unlikely that the dissolved grease composition 10 would remain in place without flowing. Therefore, a combustion test conducted in a manner that guides the liquid grease composition away from the heat source, as in this embodiment, is considered a test method that closely resembles the actual usage environment.

[0042] As described above, the combustion test of this embodiment makes it possible to appropriately evaluate the flame retardancy performance of the flame retardant grease composition 10 by conducting a combustion test that is close to the usage environment of the grease composition 10.

[0043] (Flame-retardant grease composition 10) The flame-retardant grease composition 10 of this embodiment is composed mainly of a base oil and contains a thickener. The flame-retardant grease composition 10 may also contain additives. Furthermore, the flame-retardant grease composition 10 of this embodiment has flame-retardant properties that self-extinguish within 3 minutes after ignition, as evaluated by the combustion test method of the composition of this embodiment. The temperature of the iron ball introduced as the heat source is set to 950°C.

[0044] To ensure such flame-retardant performance, in this embodiment the thickener has a metal soap group. The thickener is preferably calcium 12-hydroxystearate or lithium 12-hydroxystearate.

[0045] Here, the flame-retardant grease composition 10 of this embodiment is used, for example, as a lubricant. For example, the grease composition 10 of this embodiment is applied to bearings (centralized lubrication system) of machinery such as steelmaking equipment.

[0046] <Base oil> The base oil consists of, for example, mineral oil alone or a mixture of mineral oil and synthetic oil. Examples of mineral oil include vacuum distillation oil (vacuum distillation residue oil, etc.) and mineral oils with a molecular weight of 1000 to 3000 in polystyrene equivalent. Examples of synthetic oil include synthetic hydrocarbon oil, ester-based synthetic oil, phenyl ether-based synthetic oil, silicone-based synthetic oil, fluorine-based synthetic oil, or mixtures thereof.

[0047] It is preferable to use a base oil with a flash point of 250°C or higher. In other words, from the viewpoint of flame retardancy, it is desirable to have flame retardancy of Class 4 petroleum or higher, so it is preferable to use a base oil with a flash point of 250°C or higher.

[0048] Furthermore, the base oil preferably contains 20% by mass or more of vacuum distilled oil having a molecular weight of 1000 to 3000 in polystyrene equivalent. In other words, by blending a base oil having a molecular weight of 1000 to 3000 in polystyrene equivalent, the flash point can be raised.

[0049] Furthermore, the base oil has a kinematic viscosity of 300 mm at 40°C. 2 It is preferable that the value be / s or higher.

[0050] Furthermore, in order to increase the amount of heat that the flame-retardant grease can tolerate, it is preferable that the specific heat of the base oil be above a certain value. The higher the amount of heat that can tolerate, the more flame-retardant the grease can be.

[0051] <Thickener> The thickener of this embodiment has a metal soap group. The thickener used in this embodiment is not a bentone-based thickener that works well at very high temperatures, but rather a metal-based thickener that dissolves at low temperatures. The thickener preferably contains calcium 12-hydroxystearate and lithium 12-hydroxystearate. In this case, the thickener of this embodiment has a configuration that combines a lithium-based thickener and a calcium-based thickener.

[0052] This thickener allows for adjustment of the dissolution temperature by including a calcium-based thickener with a low dissolution temperature and a lithium-based thickener with a high dissolution temperature. The optimal mixing ratio of calcium 12-hydroxystearate to lithium 12-hydroxystearate is within the range of 9:1 to 6:4 in molar ratio.

[0053] <Other properties of grease composition 10> It is preferable that the consistency of the grease composition 10 (JIS K2220) is within the range of 265 to 385. In other words, when considering a case where the grease composition is supplied to equipment by automatic lubrication, it is desirable that the consistency falls within the range of 265 to 385. If the consistency is 386 or higher, liquefaction is more likely to occur when scale powder is mixed in, and there are concerns about grease leakage from the bearings. On the other hand, if the consistency is less than 265, the pumpability is poor and liquefaction is less likely to occur, but there are concerns that the grease around the scale powder will be exposed to high temperatures and will not be able to dissipate heat.

[0054] Furthermore, it is preferable that the dropping point (JIS K2220) of the grease composition 10 is 300°C or lower. The burning time of the flame-retardant grease composition 10 is related to its melting temperature. Grease compositions with a high melting temperature do not easily change into a liquid state, resulting in poor cooling efficiency, maintaining a high temperature at the heat source, and thus a longer burning time. On the other hand, greases with a low melting temperature change into a liquid state easily, resulting in high cooling efficiency and faster cooling of the heat source. Therefore, the grease composition 10 of this embodiment is characterized by a low melting temperature, thereby improving its flame-retardant performance.

[0055] Furthermore, the grease composition 10 is preferably configured to ignite when exposed to a heat source of 950°C or higher. Here, the temperature of the iron ball used as the heat source during the combustion test was changed, and the temperature at which ignition began was also investigated (see Figure 8). It was confirmed that the grease composition 10 of this embodiment ignited when a heat source of 950°C or higher was used.

[0056] <Additives> The grease composition 10 of this embodiment may contain antioxidants, extreme pressure agents, rust inhibitors, lubricity agents, wear inhibitors, solid additives, etc., as needed. Among these, it is preferable to add extreme pressure agents, lubricity agents, and rust inhibitors. Adding more additives than necessary may reduce the flame retardancy. The content of these additives should be kept within a range of approximately 0.01 to 10 parts by weight relative to the total.

[0057] In other words, with respect to the flame-retardant grease composition 10, it is preferable to mix one or more of the following: a sulfur-based extreme pressure agent, a calcium sulfonate-based rust inhibitor, and a polymer ester-based oiliness agent, so that it can be used in a wide range of equipment.

[0058] <Effects and Effects> In the flame-retardant grease composition 10 of this embodiment, when the grease composition 10 ignites, the heat source can be cooled more quickly, and the burning time can be suppressed to within 3 minutes.

[0059] To improve cooling efficiency, a grease composition 10 that dissolves at a temperature lower than the flash point of the base oil may be considered to enhance flame retardancy. In terms of solubility, greases with a low dropping point are considered advantageous. A method of adjusting solubility may involve combining multiple thickeners.

[0060] Furthermore, since the ignition temperature is the starting point of combustion, it is desirable that the ignition temperature of the grease composition 10 be high. To achieve this, it is desirable to use a base oil that has superior flame retardancy, such as one with a high flash point or a high specific heat.

[0061] The dissolved grease composition 10 absorbs heat as a cooling medium. Furthermore, when the grease composition 10 is used in bearings or the like, it is desirable that it has high viscosity and remains in place. To evaluate a base oil with the above characteristics, a base oil with a viscosity index of 95 or higher is preferred.

[0062] Furthermore, the grease composition 10 of this embodiment was actually filled into an automatic lubrication device and used in steelmaking equipment, and it was confirmed that the equipment operated without any problems.

[0063] Herein, the grease composition 10 of this embodiment is suitable for lubricating bearings and gears used in high-temperature environments such as ironmaking equipment and forging equipment. When using the grease composition 10 of this embodiment as a lubricant for bearings and gears, it can be used in accordance with conventionally known methods. The grease composition has the effect of being less likely to ignite even when exposed to high temperatures or when high-temperature scale is scattered.

[0064] (others) This disclosure may also take the following form: (1) Disclosure 1 is a method for testing the combustion of a grease composition, The grease composition to be evaluated is placed in a container with an open top, and a heat source is introduced into the grease composition from above to ignite it. The above container guides the liquid component of the contained grease composition, which has become liquid due to heat, away from the heat source into which it was introduced. A method for testing the flammability of a grease composition. (2) Disclosure 2 states that the bottom surface of the container consists of a mounting area on which the grease composition is placed and a non-mounting area located on the outer periphery of the mounting area. A method for testing the flammability of a grease composition. (3) Disclosure 3 states that the induction is performed at one or more openings provided in at least one of the lower part of the wall and the bottom surface of the container. A method for testing the flammability of a grease composition. (4) Disclosure 4 has a storage section for storing the liquid component discharged from the opening, A method for testing the flammability of a grease composition. (5) Disclosure 5 states that the bottom surface of the container consists of a placement area on which the grease composition is placed and a non-placement area located on the outer periphery of the placement area, and that the induction is performed in the placement area described above. A method for testing the flammability of a grease composition. (6) Disclosure 6 states that the non-installation area is located below the installation area. A method for testing the flammability of a grease composition. (7) Disclosure 7 states that the heat source is a high-temperature iron ball, When the area of ​​the base is converted to a circle, the diameter of the base is 2.5 times or more the diameter of the iron ball. A method for testing the flammability of a grease composition. (8) Disclosure 8 comprises a base oil and a thickener, wherein the thickener has a metal soap group and is flame retardant, self-extinguishing within 3 minutes after being ignited using a heat source of 950°C in the combustion test method of the grease composition described in claim 1. Grease composition. (9) Disclosure 9 states that the flash point of the base oil is 250°C or higher. Grease composition. (10) Disclosure 10 states that the base oil contains 20% by mass or more of vacuum distilled oil having a molecular weight of 1000 to 3000 in polystyrene equivalent, Grease composition. (11) Disclosure 11 states that the kinematic viscosity of the base oil at 40°C is 300 mm 2 It is greater than or equal to / s. Grease composition. (12) Disclosure 12 states that the thickener comprises calcium 12-hydroxystearate and lithium 12-hydroxystearate, and the mixing ratio thereof is in the range of 9:1 to 6:4 in molar ratio. Grease composition. (13) Disclosure 13 states that the consistency of the grease composition (JIS K2220) is in the range of 265 to 385. Grease composition. (14) Disclosure 14 states that the dropping point (JIS K2220) of the grease composition is 300°C or lower. Grease composition. (15) Disclosure 15 is ignited by a heat source of 950°C or higher, Grease composition. (16) Disclosure 16 contains one or more additives selected from extreme pressure agents, rust inhibitors, and oiliness agents. Grease composition. (17) Disclosure 17 is applicable as a lubricant, Grease composition. (18) Disclosure 18 is a bearing containing the grease composition of the present disclosure. (19) Disclosure 19 is a gear having the grease composition of this disclosure enclosed within it. [Examples]

[0065] Next, an example of this embodiment will be described. To confirm the flame retardant properties of the grease composition 10, a conventional combustion test as shown in Figure 9 and a combustion test based on this embodiment were conducted. The temperature of the steel ball used as the heat source was set to 950°C. 20g of the grease composition was used during the test. The steel ball used had a diameter of 19mm. A container with an inner diameter of 53 mm and a height of 20 mm was used. However, in the "combustion test method of this embodiment," as described later, a container with four openings 3A, as shown in Figure 1, was used.

[0066] Here, the grease compositions of Examples 1-3 and the Comparative Example were used as examples of grease composition 10. Similar combustion tests were also conducted on Samples 1-4. Samples 1-4 are compositions containing one or more components selected from the base oil, thickener, and additives of Example 3. Sample 1 corresponds to Example 3. Table 1 shows the grease compositions of Examples 1-3 and Comparative Example 1. Table 2 shows the compositions of Samples 1-4.

[0067] [Table 1]

[0068] [Table 2]

[0069] Here, Mineral oil A: Paraffinic mineral oil (kinematic viscosity at 40°C: 467 mmHg) 2 (Voltage: / s, viscosity index: 96, flash point: 316°C, contains 40% polystyrene with a molecular weight of 1000-3000) Mineral oil B: Paraffinic mineral oil (kinematic viscosity at 40°C: 136 mmHg) 2 (Voltage: / s, viscosity index: 96, flash point: 272°C, contains 10% of polystyrene with a molecular weight of 1000-3000) Thickener (lithium, calcium soap): Lithium hydroxide, and a reaction between calcium hydroxide and 12-hydroxystearic acid. The mixing ratio of the reactants, calcium 12-hydroxystearate and lithium 12-hydroxystearate, was 7:3 in molar ratio. Thickener (urea): Octylamine, and a compound obtained by reacting stearylamine with diphenylmethane diisocyanate (MDI). Additive A: Antioxidant Additive B: Extreme pressure agent Additive C: Rust inhibitor Additive D: Oily agent That is the case.

[0070] (Conventional combustion test method) Figure 5 shows the results of the combustion time obtained by a conventional combustion test, as shown in Figure 9, for the grease compositions of Examples 1 to 3 and Comparative Example 1. As can be seen from Figure 5, Comparative Example 1, which is a general-purpose grease and not a flame-retardant grease, did not continue burning and was extinguished within 3 minutes. Thus, it is considered that conventional combustion test methods are not able to adequately evaluate the flame retardancy of grease composition 10.

[0071] In conventional combustion tests, the general-purpose grease (Comparative Example 1) extinguished within 3 minutes, which is likely due to its heat dissipation performance. In the sealed container 1, the molten grease comes into contact with the heat source, resulting in a state of superior cooling capacity for the heat source.

[0072] For confirmation, conventional combustion tests were performed on four types of samples 1-4 (see Table 2) using the base oil, thickener, and additive from Example 3: base oil, base oil + thickener, base oil + additive, and base oil + additive + thickener. The results are shown in Figure 6. As shown in Figure 6, it was confirmed that only the semi-solid grease composition 10 containing base oil and thickener burned for a long time. In other words, as seen in Sample 1 and Sample 3, the presence of a thickener extends the burning time. In this study, the base oil, thickener, and additives used were those shown in Table 2.

[0073] (Combustion test method of this embodiment) In this example, a first container 1 (see Figure 1) having the four openings 3A described above was used. A combustion test was then conducted by placing the grease composition 10 in the center of the container 1 and introducing a high-temperature (950°C) iron ball into the grease composition 10. The results are shown in Figure 7.

[0074] In this combustion test method, an iron ball (heat source) was placed into the grease composition 10, and it was confirmed that when the grease composition 10 began to dissolve, the melted grease flowed out from the opening 3A into the surrounding area. In this combustion test, as shown in Figure 7, it was confirmed that Comparative Example 1, a general-purpose grease, continued to burn. On the other hand, as can be seen from Examples 1 to 3, it was confirmed that flame-retardant greases self-extinguished over time.

[0075] Thus, it was found that the combustion test method based on this embodiment can evaluate flame retardancy with greater accuracy than conventional methods. Furthermore, it was confirmed that similar results can be obtained for any of the second to fourth containers 1.

[0076] Furthermore, Example 3 is a flame-retardant grease composition 10 of this embodiment, using a lithium-based thickener and a calcium-based thickener. It was confirmed that Example 3, based on this embodiment, exhibits flame retardancy at a level comparable to, or slightly improved compared to, cases where only a lithium-based thickener is used or when a urea-based thickener is used.

[0077] Here, it is easy to imagine that the grease composition 10 is actually used in environments such as bearing devices, where it is used in inclined locations or in environments that are not sealed off. For this reason, evaluating the grease composition 10 under conditions where the liquid component is far from the heat source, as in this embodiment, makes it possible to obtain test results that are more in line with the actual usage environment of the grease composition 10.

[0078] Furthermore, to measure the burning time, it is necessary to use a heat source that is heated to a temperature above the ignition temperature of the grease. Also, the heat source must have enough heat to raise the grease composition 10 surrounding the heat source to the ignition temperature immediately after it is applied; otherwise, ignition will not occur. However, when investigating the ignition temperature, it is preferable to start with a heat source that is lower than the above and gradually increase it to determine the conditions under which ignition occurs, as this is a good way to evaluate the flame-retardant grease.

[0079] (Regarding the ignition temperature) Here, we changed the temperature of the iron ball used as the heat source during the combustion test and investigated the temperature at which ignition would begin. The results are shown in Figure 8. As can be seen from Figure 8, combustion tests of the flame-retardant grease compositions 10 of Examples 1 to 3 confirmed that ignition occurred when a heat source of 950°C or higher was used.

[0080] Furthermore, as can be seen from Figure 8, it was confirmed that Example 3, based on this embodiment, has an ignition onset temperature that is 50°C or more higher than that of the conventional products, Examples 1 and 2. This indicates that the grease composition 10 based on this embodiment has excellent flame retardancy. [Explanation of symbols]

[0081] 1 Combustion container 2 Bottom part 2A opening 3 wall 3A opening 4. Storage section 10 Grease Compositions 20 Conventional containers 21. Iron ball (heat source) S Mounting area T Non-placement area

Claims

1. A method for testing the flammability of a grease composition, The grease composition to be evaluated is placed in a container with an open top, and a heat source is introduced into the grease composition from above to ignite it. The above container guides the liquid component of the contained grease composition, which has become liquid due to heat, away from the heat source into which it was introduced. A method for testing the flammability of a grease composition.

2. The bottom surface of the above container consists of a placement area on which the grease composition is placed and a non-placement area located on the outer periphery of the placement area. A method for testing the grease composition described in claim 1.

3. The above induction is performed through one or more openings provided in at least one of the lower part of the container wall and the bottom surface. A method for testing the flammability of a grease composition according to claim 1 or claim 2.

4. It has a storage section for storing the liquid component discharged from the above-mentioned opening, A method for testing the grease composition described in claim 3 for combustion.

5. The bottom surface of the above container consists of a placement area on which the grease composition is placed and a non-placement area located on the outer periphery of the placement area, and the induction described above is performed in the placement area. A method for testing the grease composition described in claim 1.

6. The above non-mounting area is located below the above-described mounting area. A method for testing the grease composition described in claim 5.

7. The heat source mentioned above is a hot iron ball. When the area of ​​the base is converted to a circle, the diameter of the base is 2.5 times or more the diameter of the iron ball. A method for testing the grease composition described in claim 5.

8. The grease composition comprises a base oil and a thickener, wherein the thickener has a metal soap group, and is flame-retardant, self-extinguishing within 3 minutes after being ignited using a heat source at 950°C according to the combustion test method of the grease composition described in claim 1. Grease composition.

9. The flash point of the above base oil is 250°C or higher. The grease composition according to claim 8.

10. The above base oil contains 20% by mass or more of vacuum distilled oil having a molecular weight of 1000 to 3000 in polystyrene equivalent. The grease composition according to claim 8.

11. The kinematic viscosity of the above base oil at 40°C is 300 mmHg. ２ / s or greater, The grease composition according to claim 8.

12. The thickener described above contains calcium 12-hydroxystearate and lithium 12-hydroxystearate, and their mixing ratio is in the range of 9:1 to 6:4 in molar ratio. The grease composition according to claim 8.

13. The consistency of the grease composition (JIS K2220) is within the range of 265 to 385. The grease composition according to claim 8.

14. The dropping point (JIS K2220) of the grease composition is 300°C or lower. The grease composition according to claim 8.

15. It ignites when exposed to a heat source of 950°C or higher. The grease composition according to claim 8.

16. It contains one or more additives selected from extreme pressure agents, rust inhibitors, and oiliness agents. The grease composition according to claim 8.

17. Applied as a lubricant, The grease composition according to claim 8.

18. A bearing containing the grease composition described in any one of claims 8 to 17.

19. A gear comprising a grease composition as described in any one of claims 8 to 17.

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