Injection lubricant

Abstract

To provide an injection lubricant that achieves low friction by penetrating into a minute gap without squeezing out or causing debris to adhere to its surrounding.SOLUTION: An injection lubricant consists only of tungsten disulfide powder and a volatile solvent, with the tungsten disulfide powder content being 25 wt.% or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an injectable lubricant for use in small gaps, for example, between sliding surfaces of a bicycle. [Background technology]

[0002] Oil and wax are known as lubricants to be injected into sliding parts, and as a more powerful lubricant, a mixture of oil or wax with a solid lubricant component that has a small coefficient of friction is also known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-33491 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned oil- or wax-based lubricants have excellent adhesion to required areas, but have the problem that they are difficult to penetrate into small gaps, such as those in bicycle chains and bearings. Because oil and wax are forcibly pushed into the gaps from the outside, excess wax and other substances end up adhering not only to the sliding parts but also to the outer periphery. Foreign matter such as sand and dust adheres to the oil and wax and forms lumps. In addition, in the case of bicycle chains, etc., solidified wax and other substances can fly off the chain and into the surrounding area while riding.

[0005] An object of the present invention is to provide an injectable lubricant which smoothly penetrates into minute gaps, does not spill out to the outside, and does not cause foreign matter to adhere, and achieves low friction. [Means for solving the problem]

[0006] The first invention is an injectable lubricant to be injected into minute gaps between sliding surfaces, which is composed only of tungsten disulfide powder and a volatile solvent, and the content of the tungsten disulfide powder is less than 25% by weight.

[0007] In a second aspect of the present invention, the volatile solvent is a lower alcohol. Effect of the Invention

[0008] According to the first aspect of the present invention, a low-viscosity liquid lubricant can be easily injected into minute gaps. The injected lubricant spreads over the sliding surface, and after the volatile solvent evaporates, only tungsten disulfide remains on the sliding surface, achieving low friction. Furthermore, since the lubricant does not contain any sticky substances such as oil or wax, dust and other particles will not adhere to the lubricant and form lumps, which will then scatter.

[0009] Furthermore, since the tungsten disulfide does not protrude from where it is needed, no tungsten disulfide is wasted. Furthermore, when used on bicycles, the low-viscosity liquid lubricant can be injected into minute gaps while the chain is still attached to the bicycle. For example, when applying wax to a chain, the chain must be removed from the bicycle and immersed in the wax that has been heated to make it liquid, allowing the wax to penetrate. However, using the lubricant of this invention eliminates the need to melt the wax, remove the chain from the bicycle, and then reinstall the chain.

[0010] According to the second aspect of the present invention, the viscosity of the lubricant is low, making it easy to inject into minute gaps. Also, since the volatile solvent is water-based, there is no need to wipe off any liquid that has spilled out of the gap. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram of a vertical penetration test method for confirming the permeability of a lubricant into a small gap. [Diagram 2] FIG. 2 is a photograph showing the results of the vertical infiltration test. [Diagram 3] FIG. 3 is an explanatory diagram of the horizontal penetration test method according to the embodiment. [Figure 4] Figure 4 is a schematic diagram showing the results of the horizontal penetration test, where (a) is for sample F (30 [wt%]) and (b) is for sample G (25 [wt%]). [Diagram 5] FIG. 5 is a table showing the horizontal penetration test results. [Figure 6] FIG. 6 is a graph showing the results of the horizontal penetration test. [Figure 7] FIG. 7 is a photograph showing the spread state of the lubricant according to the embodiment. [Figure 8] FIG. 8 is a table showing the results of the diffusion test. [Figure 9] FIG. 9 is a partial cross-sectional view of a bicycle chain. [Figure 10] FIG. 10 is a table showing the results of the running tests. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will be described below. The injection lubricant of the embodiment is a liquid consisting of only isopropyl alcohol and tungsten disulfide, which is obtained by mixing tungsten disulfide powder with isopropyl alcohol as a volatile solvent. Specifically, isopropyl alcohol with a purity of 99.9% or higher was added to the weighed tungsten disulfide powder, placed in a container with the lid closed, and shaken to mix. At this time, the content of the tungsten disulfide powder was changed to prepare lubricants with multiple concentrations.

[0013] The prepared lubricant is liquid, and appears to become somewhat more viscous as the content of tungsten disulfide powder increases. The tungsten disulfide powder has an average particle size of 0.5 μm, a static friction coefficient of 0.07, and a dynamic friction coefficient of 0.03. When the lubricant of the embodiment is injected into the minute gap that forms the sliding surface, the isopropyl alcohol evaporates in the minute gap in a short time, and only the tungsten disulfide powder remains on the sliding surface. As described above, tungsten disulfide powder is a material with an extremely low coefficient of friction, and is therefore expected to function as a solid lubricant after the isopropyl alcohol has evaporated.

[0014] [Vertical infiltration test] A test for confirming the permeability of the lubricant of the embodiment into a small gap will be described below. Figure 1 shows the test fixture used in the vertical infiltration experiment. In this test, as shown in Fig. 1, spacers 3 and 4 were provided between a pair of glass plates 1 and 2, and the distance d between the glass plates 1 and 2 was adjusted to 60 [μm]. The glass plates 1 and 2 were slide glasses for preparations, with a length S of 76 [mm] and a width W of 25 [mm], and had a smooth surface.

[0015] With the glass plates 1 and 2 as described above standing with their widths W in the up-down direction, lubricant was dripped from above between the glass plates 1 and 2 using a dropper 5 at the tip of a bottle (not shown). After that, the penetration distance of the lubricant from the upper edge of the glass plates 1 and 2 between the glass plates 1 and 2 was measured. The lubricant samples that were dropped were of four types, with the tungsten disulfide powder content being 60% (by weight) for sample A, 50% (by weight) for sample B, 45% (by weight) for sample C, and 40% (by weight) for sample D. The 60 μm spacing corresponds to the gaps g1, g2, g3, and g4 between the components of the bicycle chain shown in Figure 9. The gaps g1, g2, g3, and g4 between the components of the bicycle chain are likely to differ depending on the bicycle chain manufacturer and specifications, but we believe that they will not deviate significantly from the 60 μm spacing, regardless of the bicycle chain manufacturer and specifications.

[0016] [Vertical infiltration test results] FIG. 2 shows the results of a penetration test in which lubricants containing different amounts of tungsten disulfide powder were penetrated between the glass plates 1 and 2, and is a photograph taken from the front side of the glass plate 1. The content ratio of tungsten disulfide powder is shown in the photographs of samples A, B, C, and D from the left in Figure 2. The black area spreading between glass plates 1 and 2 in this photograph is the tungsten disulfide powder in the lubricant. The reach of the tungsten disulfide powder from the top end 1a of glass plate 1, as shown in Figure 2, was 2.60 [mm] for sample A, 3.25 [mm] for sample B, 5.15 [mm] for sample C, and 5.70 [mm] for sample D.

[0017] The test results showed that when the tungsten disulfide powder content was 50% by weight or more, the entire amount of the dropped lubricant did not penetrate between the glass plates 1 and 2, and the tungsten disulfide powder remained piled up on the upper edges of the glass plates 1 and 2, and the penetration distance was less than 4 mm. In contrast, when the content of tungsten disulfide powder was 45% by weight or less, which corresponds to sample C, the entire amount of the dropped lubricant penetrated between the glass plates 1 and 2, and the penetration distance was 5 mm or more. In addition, no tungsten disulfide powder remained on the upper edges of the glass plates 1 and 2. This result is believed to be due to the fact that as the content of tungsten disulfide powder increases, the viscosity of the lubricant increases.

[0018] On the other hand, it is considered that the lower the content of tungsten disulfide powder, the lower the viscosity of the lubricant and the better its permeability. For example, in the case of sample E (not shown) in which the content of tungsten disulfide powder is 12.5 [wt %], it has been confirmed that the lubricant dropped from above the glass plates 1 and 2 reaches up to 25 [mm], which is the lower end of the glass plates 1 and 2. These results show that when the tungsten disulfide content is 45% by weight or more, the entire amount of the dropped lubricant cannot penetrate into a minute gap of 60 μm.

[0019] [Horizontal penetration test] Next, a horizontal penetration test was carried out as shown in Fig. 3. In this horizontal penetration test, the same glass plates 1 and 2 as those used in the vertical penetration test shown in Fig. 1 were placed horizontally, and one drop of lubricant was injected between the glass plates 1 and 2 from a single injection point p using a dropper 5. The seven samples used in this test were those with a tungsten disulfide powder content of 30% by weight: Sample F, 25% by weight: Sample G, 24% by weight: Sample H, 23% by weight: Sample I, 22% by weight: Sample J, 21% by weight: Sample K, and 20% by weight: Sample L.

[0020] The permeation state of each sample was photographed, and the permeation area was calculated using image processing software. In this horizontal penetration test, the lubricant is forced into the tiny gap between the glass plates 1 and 2 by the pressing force of the dropper 5, but is less susceptible to the effects of gravity as in the vertical penetration test. In fact, this is thought to be closer to the state in which the lubricant is injected from the gap g1 of a bicycle chain toward the pin 11 (see Figure 9).

[0021] [Horizontal penetration test results] Figures 4(a) and (b) are schematic diagrams of the permeation state of sample F (30 [wt%]) and sample G (25 [wt%]) with a powder content of tungsten disulfide. In sample F, as shown in Figure 4(a), the powder spread along the edges of glass plates 1 and 2 on both sides of injected part p, but there was almost no permeation in the injection direction indicated by the arrow. In contrast, it was confirmed that sample G permeated in the direction of the arrow, as shown in Figure 4(b). All of samples F to L, which have a powder content of 25 [wt%] or less, permeated in the direction of the arrow.

[0022] Figure 5 is a table showing the penetration area calculated using image processing software, and Figure 6 is a graph of the results of Figure 5. As shown in Figures 5 and 6, the increase in the penetration area relative to the change in powder content is rapidly increased at 25% by weight or less.

[0023] From these results, it can be seen that in the horizontal penetration test, as in the vertical penetration test, the lower the content of tungsten disulfide powder, the easier it is to penetrate and the larger the penetration area. In particular, from the results of Figures 5 and 6, it was found that when the content of tungsten disulfide is 25 [wt%], the permeability of the lubricant changes and the rate of change in the penetration area also changes. In other words, it was found that the permeability suddenly increases when the content of tungsten disulfide powder is 25% by weight or less.

[0024] On the other hand, when the content of tungsten disulfide powder is 30% by weight, the permeability from the injection part p to the small gap is low, and the tungsten disulfide powder solidifies along the opening. Therefore, it is difficult to inject additional lubricant and to spread the lubricant to the small gap. Therefore, it is considered preferable that the tungsten disulfide powder content be 25% by weight or less for a lubricant to be injected into minute gaps between sliding surfaces, such as the chain and bearing parts of a bicycle.

[0025] [Diffusion test] Next, a diffusion test was carried out in which the content ratio of the tungsten disulfide powder was changed and the extent to which the tungsten disulfide powder spread in the lubricant was confirmed. The test samples were three types, with the tungsten disulfide powder content being 60 [wt%], sample A being 12.5 [wt%], and sample M being 1.0 [wt%]. A drop of each of the samples A, E, and M was placed on a horizontally placed piece of paper using a dropper, and the area of ​​the spread was measured. This measurement was performed 10 times for each of the samples A, E, and M.

[0026] [Diffusion test results] FIG. 7 is a photograph showing the spread of the dropped lubricant. For each sample, the spread on the paper was measured. Specifically, the major and minor axes of the area where the lubricant spread were measured, and the area of ​​the circle with the average diameter was taken as the spread area. The results are shown in Figure 8.

[0027] For each sample, the average value of the 10 points was 168.1 mm for sample M, which contains 1% by weight of tungsten disulfide powder. 2 ], and sample E with 12.5 [wt %] was 69.0 [mm 2 ], and 5.4 [mm 2 〕. In the above sample A, the tungsten disulfide powder was lifted above the paper and solidified. It is thought that the isopropyl alcohol evaporated before the liquid had enough time to diffuse because the powder content was high in sample A. On the other hand, the diffusion area of ​​sample F is very wide, so the color appears very light in the photo image.

[0028] The above test results show that the lower the tungsten disulfide powder content, the greater the spread of the liquid lubricant, but even in sample M, which has a low content of 1.0 wt.%, the tungsten disulfide powder spreads sufficiently along with the liquid.

[0029] [Driving test] Next, in order to confirm the effect of the lubricant of the above embodiment, a bicycle filled with the lubricant was subjected to a running test. The chain 6 shown in Figure 9 is the structure of the bicycle chain used in the running test. The chain 6 is made up of outer plates 7, 7, inner plates 8, 8, rollers 9, bushes 10, and pins 11. The gap g1 between the outer plate 7 and the inner plate 8, the gap g2 between the inner plate 8 and the end face of the roller 9, the gap g3 between the inner surface of the roller 9 and the outer surface of the bush 10, and the gap g4 between the inner surface of the bush 10 and the outer surface of the pin 11 are each approximately 60 μm.

[0030] The test method is as follows. The lubricant of the embodiment and oil for bicycle chains are poured into the above gaps g1, g2, and g3, as well as into the hub bearing and freewheel ratchet, and the running time for a certain distance is compared. It is assumed that the lubricant penetrates into gap g4 through gap g1. The lubricant in the embodiment is sample E, which uses isopropyl alcohol as a solvent and contains 12.5% ​​by weight of tungsten disulfide powder, and the bicycle chain oil in the comparative example is Road Race SP / BIc-004 from AZ Co., Ltd. One drop each of these was injected near the gaps g1, g1 on both ends of the pin 11. The bicycle chain used was Shimano DURA-ACE CN-M9100.

[0031] Each lubricant was injected and the vehicle was driven multiple times over the same section of National Route 134, a distance of 21.01 km. The equipment, parts, bicycles, tire pressure, and bicycle riders used were all the same, and the distance and time traveled were measured using an app (Strava) that uses GPS information.

[0032] [Driving test results] The results of the running test are shown in Fig. 10. As shown in Figure 10, the running time was 47 minutes 50 seconds when the lubricant of the embodiment of the present invention (sample E) containing 12.5% ​​by weight of tungsten disulfide powder was injected, and it was 48 minutes 40 seconds when general bicycle chain oil was injected. As described above, when the lubricant of the embodiment was used, the time was 50 seconds, or about 1.71%, faster on average than when oil was used.

[0033] The test results when using the lubricant of the above embodiment are the average of 23 measurements, while the test results when using oil are the average of 22. Both are averages of more than 20 measurements, and significant differences are observed. From this, it was confirmed that the lubricant of the embodiment containing tungsten disulfide powder in isopropyl alcohol achieves lower friction resistance and less power loss than bicycle chain oil.

[0034] In addition, the lubricant of the embodiment is a liquid with isopropyl alcohol as a solvent, and contains less than 25% by weight of tungsten disulfide powder, so that it has high permeability and diffusibility into minute gaps, and easily reaches gaps g1, g2, g3, g4, etc. In addition, since isopropyl alcohol is a volatile solvent, it evaporates in a relatively short time after the liquid lubricant is poured in. Therefore, only the tungsten disulfide powder remains in the minute gaps, and it exerts its full effect as a solid lubricant.

[0035] Moreover, the lubricant of the embodiment does not contain any sticky substances such as oil or wax, so there is no risk of sticky substances attracting sand or dust and forming lumps, and these lumps are not scattered. As described above, in the lubricant of the embodiment, after the solvent evaporates, only the tungsten disulfide powder remains on the sliding surface and exerts a lubricating function, so that the low friction effect is stable. Furthermore, the lubricant in this embodiment is a liquid with low viscosity that can be injected into small gaps, so unlike when using a lubricant that contains wax, there is no need to dissolve the wax or take the time to remove and reattach the chain from the bicycle.

[0036] In the above embodiment, isopropyl alcohol is used as the volatile solvent, but the solvent is not limited to isopropyl alcohol as long as the liquid evaporates within an appropriate time after being injected into the gap. However, if a solvent is used that is too volatile and evaporates instantly, it will be difficult to maintain the liquid state of the lubricant when it is removed from the container, and it will also be difficult to handle, so it is preferable to select a liquid with moderate volatility.

[0037] In addition, lower alcohols such as isopropyl alcohol, ethyl alcohol, and methyl alcohol have low viscosity and easily penetrate into small gaps, and because they are water-based, they have the advantage of not needing to wipe off any liquid that spills out of the gap. Furthermore, isopropyl alcohol, ethyl alcohol, methyl alcohol, and the like are common solvents and easily available, so the manufacturing costs of lubricants that use them can be reduced.

[0038] The content of tungsten disulfide powder in the lubricant is preferably less than 25% by weight and is appropriately selected depending on the injection site. If the solvent evaporates over time and the powder concentration becomes too high, it is possible to dilute it with the same solvent before use.

[0039] For example, in a bicycle chain (Shimano DURA-ACE CN-M9100) as shown in FIG. 9, the total area of ​​the sliding surfaces, which are the opposing surfaces of the gaps g1, g2, g3, and g4, and the outer circumferential surface of the roller 9, per link is about 215 mm 2 The concentration of tungsten disulfide powder in two drops that can cover this area with at least one layer of tungsten disulfide powder was calculated to be about 3.9% by weight. In other words, if the tungsten disulfide powder content is 3.9% by weight, two drops of lubricant can supply enough tungsten disulfide powder to coat the entire sliding surface of one link.

[0040] The lubricant used in the running test (12.5% ​​by weight, sample E) contains more than three times the amount of tungsten disulfide powder as the 3.9% by weight mentioned above. Therefore, it is believed that in the running test, injection of two drops per link provided enough tungsten disulfide powder to cover the entire sliding surface. In this example, the volume of one drop is 0.013 cm 3 ], and the tungsten disulfide powder was calculated as a sphere with a diameter of 0.5 [μm].

[0041] The injection lubricant of the present invention can be used in the same manner as described above when lubricating sliding surfaces having minute gaps other than bicycle chains. If the tungsten disulfide powder content is less than 25% by weight, the ability to penetrate into small gaps is sufficient, but if the content is reduced to increase the ability to penetrate, the amount injected can be increased according to the sliding area requiring lubrication. [Industrial Applicability]

[0042] Suitable for lubricating various small gaps.

Claims

1. An injectable lubricant to be injected into a minute gap between sliding surfaces, It consists only of tungsten disulfide powder and a volatile solvent, The content of the tungsten disulfide powder is 25% by weight or less. Injectable lubricant.

2. The volatile solvent is a lower alcohol. The injection lubricant of claim 1.

Images