Sliding Structure

Abstract

To provide a slide structure that realizes excellent slide ability during sliding.SOLUTION: The slide structure comprises: a lubricating liquid having a kinematic viscosity of 500 mm2 / s or less at 40°C; and rubber, wherein the slide structure has a volume change rate of 10 (%) or less when the rubber was immersed in a lubricating liquid at 25°C for 336 hours according to JIS K6258:2016.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a sliding structure. [Background technology]

[0002] Conventionally, in order to reduce friction between the sliding parts of rubber and metal, the friction characteristics of the sliding parts have been improved by increasing the rotation speed of the sliding parts or increasing the viscosity of the lubricating liquid applied to the sliding parts to create a fluid lubrication state. Patent Document 1 (JP 2019-166317 A) discloses a rubber composition that contains a natural rubber component and bromobutyl rubber, etc., and has a specified range of wet friction coefficient, dry friction coefficient, DIN abrasion, and die C tear strength.

[0003] In recent years, the viscosity of lubricating liquids has been reduced in order to save energy, and low friction in the boundary lubrication region is now required in addition to the conventional low friction achieved by fluid lubrication. However, low-viscosity lubricating liquids generally have a small molecular weight, and therefore tend to be absorbed by the rubber that constitutes the sliding structure, making it difficult for the lubricating liquid to remain on the sliding surface. For this reason, there has been a demand for a sliding structure that uses a low-viscosity lubricating liquid while still providing excellent sliding performance during sliding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-166317 A Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors have discovered that by controlling the volume change rate, which is an index of the affinity between a lubricating liquid and rubber, it is possible to obtain a sliding structure that suppresses the absorption of the lubricating liquid into the rubber and exhibits an excellent sliding effect during sliding. In other words, the present invention provides a sliding structure that realizes excellent sliding ability during sliding. [Means for solving the problem]

[0006] The various aspects of the present invention are as follows. [1] Kinematic viscosity at 40°C is 500mm 2 1. A sliding structure comprising a lubricating liquid having a volumetric change rate of 10% or less when the rubber is immersed in the lubricating liquid at 25°C for 336 hours in accordance with JIS K6258:2016. [2] The sliding structure according to the above [1], wherein the rubber is at least one type of rubber selected from the group consisting of fluororubber (FKM), ethylene propylene diene rubber (EPDM) and acrylonitrile butadiene rubber (NBR). [3] The sliding structure according to the above [1] or [2], wherein the lubricating liquid is at least one lubricating liquid selected from the group consisting of hexadecane, methyl oleate, and poly-α-olefins. Effect of the Invention

[0007] It is possible to provide a sliding structure that realizes excellent sliding performance during sliding. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The sliding structure of the present invention has a kinetic viscosity of 500 mm at 40°C. 2 The rubber has a volume change rate of 10% or less when the rubber is immersed in the lubricating liquid at 25°C for 336 hours according to JIS K6258:2016. The kinetic viscosity at 40°C is 500mm 2 By using a lubricating liquid with a flow rate of less than 1 / s, energy savings can be achieved. On rubber, the kinetic viscosity at 40°C is 500mm 2Even when a lubricating liquid with a low viscosity of 1000 MPa or less is present, the rubber can be effectively prevented from absorbing the lubricating liquid and causing swelling. Therefore, when the sliding structure slides, the sliding parts are considered to be in a boundary lubrication state, but low friction can be achieved even in such a case. As a result, excellent sliding ability (low friction) can be achieved in the sliding structure having rubber.

[0009] The sliding structure of the present invention will be described in detail below. The lubricating liquid is 500mm at 40°C. 2 The kinetic viscosity of the lubricating liquid at 40°C is 1 to 500 mm 2 / s is preferable, and 3 to 400 mm 2 / s is more preferable. The lubricating liquid is not particularly limited as long as the volume change rate of the rubber is 10% or less, but examples thereof include at least one lubricating liquid selected from the group consisting of undecane, dodecane, hexadecane, isododecane, isohexadecane, octene, nonene, decene, undecene, dodecene, dipentyl ether, dibutyl ether, dipropyl ether, di-2-ethylhexyl ether, diisopentyl ether, diisobutyl ether, diisohexyl ether, ethyl isopentyl ether, propyl isopentyl ether, ethyl isobutyl ether, propyl isobutyl ether, diisobutyl ether, diisopentyl ether, ethyl hexanoate, propyl hexanoate, butyl hexanoate, isobutyl hexanoate, methyl heptanoate, ethyl heptanoate, propyl heptanoate, methyl oleate, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, and poly-α-olefin. Among these lubricating liquids, it is preferable to use at least one lubricating liquid selected from the group consisting of ethylene glycol, hexadecane, methyl oleate, and poly-α-olefins as a lubricating liquid that reduces the volume change rate of rubber.

[0010] The rubber is not particularly limited as long as the volume change rate in the lubricating liquid is 10% or less, but examples thereof include at least one rubber selected from the group consisting of silicone rubber, butyl rubber (IIR), ethylene propylene rubber (EPM), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), chloroprene rubber (CR), acrylic rubber (ACM), urethane rubber (U), fluororubber (FKM), ethylene propylene diene rubber (EPDM) and acrylonitrile butadiene rubber (NBR). The volume change rate of acrylonitrile butadiene rubber (NBR) can be controlled in the lubricating liquid by adjusting the nitrile content. Among these rubbers, at least one rubber selected from the group consisting of fluororubber (FKM), ethylene propylene diene rubber (EPDM) and acrylonitrile butadiene rubber (NBR) is preferred because it is less likely to absorb the lubricating liquid. The volume change rate of rubber was measured according to JIS K6258:2016 by soaking a rubber test piece measuring 20 x 50 x 2 mm in a lubricating liquid at 25°C. It represents the rate of change in volume when immersed in the solvent for 336 hours. The rate of change in volume of rubber measured according to the above method is 10% or less, and preferably 1% or less.

[0011] The sliding structure of the present invention may contain components other than the lubricating liquid as necessary. For example, the sliding structure may contain, as components other than the lubricating liquid, vulcanizing agents; reinforcing materials such as carbon black and white carbon; processing aids such as wax, metal soap, and carnauba wax; acid acceptors such as calcium hydroxide, magnesium oxide, zinc oxide, and hydrotalcite; antioxidants; thermoplastic resins; plasticizers; softeners; foaming agents; foaming aids; colorants; dispersants; flame retardants; tackifiers; release agents; various metal powders, and the like. These components may be dissolved or dispersed in the lubricating liquid.

[0012] (Method of manufacturing sliding structure) In one embodiment, the sliding structure is formed by crosslinking and molding a rubber material into a predetermined shape, and then assembling a sliding part including the rubber of the predetermined shape. The lubricating liquid can be applied to the surface of the rubber material to produce the rubber-like rubber. The conditions for crosslinking and molding the rubber material can be appropriately set depending on the type of rubber material.

[0013] (Sliding structure) When the sliding structure has a sliding part composed of members facing each other, both of the members facing each other may be made of rubber, or one of the members facing each other may be made of rubber and the other may be made of another material. In one embodiment of the sliding structure, the sliding part is composed of rubber and metal, and a lubricating liquid can be present between the rubber and the metal. For example, a lubricating liquid can be present between the rubber and the metal at a temperature of 500 mm at 40° C. 2 By applying a lubricating liquid having a kinetic viscosity of 100 / s or less, it is possible to achieve excellent sliding characteristics (low friction state) as a boundary lubrication state. The sliding structure is not particularly limited, and can be the sliding structure of an air conditioner compressor, an automobile engine piston, an electromagnetic valve, a plunger, a valve, a bush, a sliding bearing, etc. EXAMPLES

[0014] Preferred embodiments of the present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to these examples.

[0015] (Examples 1 to 11 and Comparative Examples 1 to 6) The volume change rate and maximum friction coefficient of each example were measured as follows. (Maximum friction coefficient) Each rubber (EPDM, NBR 1, NB2, FKM) was mixed.

[0016] [Table 1] The rubber was cross-linked to form a semi-spherical rubber pin with a radius of 2 mm. A mirror-finished SPCC (Steel Plate Carbon Fiber) was placed opposite the semi-spherical rubber pin as a sliding member. A disk made of SPCC (Cold Commercial; cold-rolled steel plate) was placed on the test piece. Next, a lubricating liquid shown in Table 2 was applied between the hemispherical rubber pin made of the rubber shown in Table 2 and the SPCC disk to obtain a sliding structure. After that, the SPCC disk was rotated for a total of 180 minutes under a load of 3 N while the rotation speed was increased stepwise in order from step 1 to step 20 shown in Table 3. The friction coefficient during rotation of the SPCC disk was calculated, and the maximum value of the friction coefficient was recorded as the maximum friction coefficient.

[0017] (Volume change rate) Rubber test pieces having a size and shape of 20 × 50 × 2 mm were prepared according to JIS K6258:2016 and made of the rubbers shown in Table 2. The volume change rate (%) of the rubber test pieces when immersed in the lubricating liquid shown in Table 2 at 25°C for 336 hours was measured. The volume change rate and maximum friction coefficient for each example are shown in Table 4.

[0018] [Table 2] HD: n-Hexadecane: 40℃ kinematic viscosity 3mm 2 / s MO: Methyl oleate: 40℃ kinematic viscosity 5mm 2 / s Poly-α-olefin (PAO A): 40℃ kinematic viscosity 5mm 2 / s (DURASYN 162, manufactured by Ineos Oligomers Japan) Poly-α-olefin (PAO B): 40°C kinematic viscosity 400mm 2 / s (DURASYN 174, manufactured by Ineos Oligomers Japan) EG: Ethylene glycol: 40℃ kinematic viscosity 9mm 2 / s

[0019] [Table 3]

[0020] [Table 4]

[0021] From the results in Table 4, it can be seen that, as shown in Examples 1 to 11, when the volume change rate is 10% or less, the maximum friction coefficient is 0.4 or less, resulting in low friction.

Claims

1. Dynamic viscosity at 40°C is 500 mm ２ / s or less, and a rubber, wherein a volume change rate of the rubber when immersed in the lubricating liquid at 25°C for 336 hours in accordance with JIS K6258:2016 is 10(%) or less, and the lubricating liquid is at least one type of lubricating liquid selected from the group consisting of hexadecane, methyl oleate, and poly-α-olefin.

2. 2. The sliding structure according to claim 1, wherein the rubber is at least one type of rubber selected from the group consisting of fluororubber (FKM), ethylene propylene diene rubber (EPDM), and acrylonitrile butadiene rubber (NBR).

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