Sealing device and rubber composition

Abstract

Provided is a novel sealing device capable of suppressing friction even in boundary lubrication or mixed lubrication. A sealing device (1) is provided with a sealing member (6), and the sealing member (6) contains a rubber composition containing a compound having a functional group at a terminal and having an aliphatic hydrocarbon group having 4 or more carbon atoms.

Description

Technical Field

[0001] This invention relates to sealing devices and rubber compositions. Background Technology

[0002] In the fields of vehicles, general machinery, and industrial machinery, various sealing devices are used to seal gaps between rotating and stationary parts, and between reciprocating and stationary parts. A typical sealing device has a sealing element made of a rubber composition that slides on the surface of opposing parts.

[0003] To suppress friction at the sliding parts of sealing components, fluid lubrication is preferred. Therefore, methods have been employed to date to ensure fluid lubrication, such as increasing the operating speed of the device or using high-viscosity lubricating fluids. On the other hand, due to energy-saving requirements, the use of lubricating fluids has tended towards lower viscosity in recent years. Therefore, there is a need to investigate methods for suppressing friction in situations where oil film formation at the sliding parts is difficult, such as boundary lubrication or mixed lubrication.

[0004] As a method for suppressing friction in boundary lubrication, it is known to improve lubricity by coating the surface of the sealing component or designing its surface shape. Additionally, a self-lubricating rubber composition is known that, instead of using lubricating oil, suppresses friction by incorporating a solid lubricant or a specific compound into the rubber, causing it to frost or seep out onto the rubber surface (e.g., Patent Documents 1-4). On the other hand, in sealing devices that rely on the presence of lubricating oil, there is still a demand for sealing components that can be manufactured without complex processes, have a high degree of freedom in surface shape, a high degree of freedom in the rubber composition used, and are easy to control in terms of friction.

[0005] Existing technical documents Invention Patent Documents Invention Patent Document 1: Japanese Patent Application Publication No. 6-166774 Invention Patent Document 2: Japanese Patent Application Publication No. 8-012733 Invention Patent Document 3: Japanese Patent Application Publication No. 2008-285562 Invention Patent Document 4: Japanese Patent Application Publication No. 2011-046812 Summary of the Invention

[0006] The problem that the invention aims to solve This invention provides a novel sealing device that can suppress friction even with boundary lubrication or mixed lubrication.

[0007] Methods for solving problems The main structure of this invention is as follows, for example.

[0008] [1] A sealing device comprising a sealing component, The sealing component comprises a rubber composition. The rubber composition contains a compound having a functional group at the end and having an aliphatic hydrocarbon group having four or more carbon atoms.

[0009] [2] In the sealing device of [1], The rubber composition contains an inorganic filler.

[0010] [3] In the sealing device of [2], The inorganic filler is at least one selected from the group consisting of carbon black, metal oxides, metal hydroxides and silicate minerals.

[0011] [4] In the sealing device of [2] or [3], The compound modifies the surface of the inorganic filler.

[0012] [5] In any of the sealing devices in [1] to [3], The functional group is a phosphate group, hydroxyl group, carboxyl group, carboxylic acid ester group, amide group, or amino group.

[0013] [6] A rubber composition comprising a compound having a functional group at the end and having an aliphatic hydrocarbon group having 4 or more carbon atoms.

[0014] [7] A method for improving the lubricant retention of a sliding surface in a sealing device, wherein a rubber composition of [6] is used for the sealing component.

[0015] [8] A sealing device comprising a sealing component. The sealing component comprises a rubber composition. The rubber composition contains an ashless friction modifier.

[0016] The effects of the invention According to the present invention, a novel sealing device is provided that can suppress friction even with boundary lubrication or mixed lubrication. Attached Figure Description

[0017] Figure 1 These are coordinate points representing the results of reciprocating kinetic friction tests on fluororubber (FKM), acrylonitrile-butadiene rubber (NBR), and acrylic rubber (ACM). The horizontal axis represents G (viscosity·velocity·contact width / tightness), and the vertical axis represents the coefficient of friction.

[0018] Figure 2These are coordinate points representing the results of a reciprocating kinetic friction test conducted using SPCC (snow-rolled steel sheet) to evaluate the effects of terminal functional groups. The horizontal axis represents the sliding speed (mm / s), and the vertical axis represents the coefficient of friction.

[0019] Figure 3 These are coordinate points representing the results of a reciprocating kinetic friction test conducted using a molded rubber composition to evaluate the effects of terminal functional groups. The horizontal axis represents the sliding speed (mm / s), and the vertical axis represents the coefficient of friction.

[0020] Figure 4 These are coordinate points representing the results of a reciprocating kinetic friction test conducted using cold-rolled steel sheet (SPCC) to evaluate the effect of the chain length of aliphatic hydrocarbon groups. The horizontal axis represents the sliding speed (mm / s), and the vertical axis represents the coefficient of friction.

[0021] Figure 5 These are coordinate points representing the results of a reciprocating kinetic friction test conducted using cold-rolled steel sheet (SPCC) to evaluate the effects of the structure (straight chain or branched chain) of aliphatic hydrocarbon groups. The horizontal axis represents the sliding speed (mm / s), and the vertical axis represents the coefficient of friction.

[0022] Figure 6 This is a cross-sectional view of a sealing device as an example of the present invention.

[0023] Symbol Explanation 1 Sealing device, 2 Shaft, 3 Housing, 4 Dustproof lip, 5 Sealing lip, 6 Sealing component, 7 Metal ring, 8 Spring, 9 Atmospheric side, 10 Sealed object side. Detailed Implementation

[0024] [lubricating oil] The sealing device of the present invention includes a sealing component. The sealing component can also be used with lubricating oil. In this specification, "lubricating oil" does not refer to components that frost or seep from the rubber composition constituting the sealing component, but rather to a lubricating fluid prepared and used independently of the sealing component. It should be noted that when the object being sealed is oil, the oil can also function as a lubricating oil. Furthermore, the phrase "used with lubricating oil" typically means that at least a portion of the sealing component is in contact with lubricating oil when the sealing device is used.

[0025] The type of lubricating oil used with the sealing device of the present invention is not particularly limited. Synthetic oils or mineral oils can be used as the base oil. Examples of synthetic oils include synthetic hydrocarbon oils, ester oils, ether oils, and glycol oils. Synthetic oils and mineral oils can be used alone or in combination.

[0026] Examples of synthetic hydrocarbon oils include polyalphaolefins, ethylene-alphaolefin copolymers, polybutene (polyisobutylene), alkylbenzenes, and alkylnaphthalenes. Examples of ester oils include diesters (esters of dicarboxylic acids and monohydric alcohols), polyol esters, and aromatic esters. Examples of ether oils include alkyl diphenyl ethers. Examples of glycol oils include polyalkylene glycols. These can be used individually or in combination.

[0027] In addition to the base oils mentioned above, lubricating oils may contain other components as needed. Examples of these other components include, but are not limited to, thickeners, extreme pressure agents, antioxidants, rust inhibitors, oiliness agents, and viscosity index improvers. Lubricating oils may also use only base oils.

[0028] [Rubber Composition] In the sealing device of the present invention, the sealing component comprises a rubber composition containing a compound having a functional group at the end and having an aliphatic hydrocarbon group having four or more carbon atoms (hereinafter, for convenience, also referred to as "compound A"). The rubber composition will now be described in detail.

[0029] (Rubber composition) The rubber composition comprises a rubber component. The type of rubber component is not particularly limited. Examples of rubber components include natural rubber, styrene-butadiene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber (nitrile rubber, NBR), hydrogenated nitrile rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), acrylic rubber (ACM), fluororubber (FKM), and silicone rubber. Preferably, the rubber component is selected from the group consisting of fluororubber (FKM), acrylonitrile-butadiene rubber (nitrile rubber, NBR), silicone rubber, and acrylic rubber (ACM).

[0030] (Compound A) Compound A can typically be a compound known as an ashless friction modifier. Compound A has a terminal functional group. The type of functional group is not particularly limited, but functional groups capable of modifying the surface of the inorganic filler (described later) are preferred. Surface modification can be achieved through physical adsorption or chemisorption, but chemisorption is preferred, i.e., adsorption through chemical bonds formed by a chemical reaction with the functional groups on the surface of the inorganic filler. Because compound A has a terminal functional group, this functional group acts as an anchor, inhibiting the dissolution of compound A into the lubricating oil, thus easily maintaining the friction-suppressing effect over a long period.

[0031] Examples of such functional groups include, for example, a phosphate group (H2PO4-), a hydroxyl group (-OH), a carboxyl group, or a carboxylic acid ester group (-COOR).1 ), carboxylic acid halide group (-COX), amide group (-CONR) 2 R 3 ) or amino (-NR 4 R 5 R 1 ~R 5 The groups shown are not specifically limited. R 1 ~R 5 The functional groups shown can be, for example, hydrogen atoms, hydrocarbon groups with 1 to 12 carbon atoms, or hydrocarbon groups with 1 to 12 carbon atoms substituted by one or more hydroxyl groups. Additionally, X represents a halogen atom. For example, fluorine, chlorine, bromine, or iodine atoms are preferred as X, with chlorine atoms being more preferred. Compound A may have two or more of the aforementioned functional groups, but preferably only one.

[0032] The hydrocarbon group having 1 to 12 carbon atoms is not particularly limited as long as it consists of carbon atoms and hydrogen atoms, and examples include chain hydrocarbon groups, aromatic hydrocarbon groups, and alicyclic hydrocarbon groups. Chain hydrocarbon groups are not particularly limited as long as the total number of carbon atoms is 1 to 12; they can be straight-chain or branched. Aromatic hydrocarbon groups are not particularly limited as long as the total number of carbon atoms is 6 to 12; they can be aromatic hydrocarbon groups with or without substituents. Furthermore, aromatic hydrocarbon groups can also have condensed polycyclic structures. Alicyclic hydrocarbon groups are not particularly limited as long as the total number of carbon atoms is 3 to 12; they can be alicyclic hydrocarbon groups with or without substituents. Furthermore, alicyclic hydrocarbon groups can also have bridged ring structures.

[0033] Examples of the chain hydrocarbon groups include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; alkenyl groups such as vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecylenyl, and dodecylenyl; and alkynyl groups such as ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptenyl, octenyl, nonynyl, decynyl, undecynyl, and dodecynyl.

[0034] Examples of aromatic hydrocarbon groups include phenyl, benzyl, tolyl, and naphthyl. Tolyl can be any one of o-tolyl, m-tolyl, and p-tolyl.

[0035] As the alicyclic hydrocarbon group, saturated or unsaturated cyclic hydrocarbon groups can be cited. Examples of cyclic hydrocarbon groups include cyclopropyl, cyclobutyl, cyclohexyl, cyclopentyl, adamantyl, norbornyl, etc.

[0036] Examples of hydroxyalkyl groups with 1 to 12 carbon atoms that are replaced by one or more hydroxyl groups include hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl, 3-hydroxypropyl, 2,3-dihydroxypropyl (glyceroyl) and other hydroxyalkyl groups.

[0037] As R 1 Preferably, hydrogen atom, alkyl or hydroxyalkyl, more preferably hydrogen atom, methyl, ethyl, n-propyl, isopropyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl, 3-hydroxypropyl or 2,3-dihydroxypropyl (glyceroyl), and even more preferably hydrogen atom or 2,3-dihydroxypropyl (glyceroyl).

[0038] As R 2 ~R 5 The preferred atom is hydrogen, alkyl or hydroxyalkyl, more preferably hydrogen, methyl, ethyl, n-propyl, isopropyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl, 3-hydroxypropyl, further preferably hydrogen, methyl or 2-hydroxyethyl, and most preferably hydrogen.

[0039] From the viewpoint of easily achieving friction reduction, the preferred functional groups are phosphate groups (H2PO4-), carboxyl groups, or carboxylic acid ester groups (-COOR). 1 ), amide group (-CONR) 2 R 3 ) or amino (-NR 4 R 5 More preferably, a phosphate group (H2PO4-) or a carboxyl group, with the phosphate group (H2PO4-) being the most preferred. It should be noted that the phosphate group, carboxyl group, and amino group can also be in the form of salts.

[0040] In addition to the aforementioned functional groups, compound A also has an aliphatic hydrocarbon group with 4 or more carbon atoms. Compound A may have one, two, three, or four or more aliphatic hydrocarbon groups with 4 or more carbon atoms. Preferably, compound A has only one aliphatic hydrocarbon group with 4 or more carbon atoms. By having an aliphatic hydrocarbon group with 4 or more carbon atoms, compound A can improve its affinity for lubricating oil, making it easier to retain lubricating oil on the sliding surface even under boundary lubrication conditions, effectively suppressing friction. That is, by using a rubber composition containing compound A in sealing components, the lubricating oil retention of the sliding surface in the sealing device is improved.

[0041] As for the aliphatic hydrocarbon group with 4 or more carbon atoms, there is no particular limitation as long as it is an aliphatic hydrocarbon group with 4 or more carbon atoms and composed of carbon atoms and hydrogen atoms. Examples include straight-chain or branched chain aliphatic hydrocarbon groups or alicyclic hydrocarbon groups. Alicyclic hydrocarbon groups may also have a bridged ring structure.

[0042] Examples of such chain-like aliphatic hydrocarbon groups include n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, 16-methylheptadecanyl (isostearyl), octadecyl, nonadecanyl, eicosyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, and octadecyl. Alkyl groups, including nonadecyl, triadecyl, tridecyl, tridodecyl, tridecyl, tritetradecyl, tripentadecyl, trihexadecyl, heptadecyl, octadecyl, nonadecyl, fortidecyl, etc.; alkyl groups having 4 to 40 carbon atoms; alkenyl groups in which one or more carbon-carbon single bonds of the alkyl groups having 4 to 40 carbon atoms are replaced by carbon-carbon double bonds; and alkynyl groups in which one or more carbon-carbon single bonds of the alkyl groups having 4 to 40 carbon atoms are replaced by carbon-carbon triple bonds, etc.

[0043] When the aliphatic hydrocarbon group with 4 or more carbon atoms is an alkenyl group, the number of double bonds is preferably 6 or less, more preferably 5 or less, even more preferably 3 or less, even more preferably 2 or less, and most preferably 1. In addition, in this case, it is preferable that the double bonds are located between the 3rd and 9th carbon-carbon bonds starting from the terminal (methyl side).

[0044] As the alicyclic hydrocarbon group, saturated or unsaturated cyclic hydrocarbon groups can be cited. Examples of cyclic hydrocarbon groups include cyclobutyl, cyclohexyl, cyclopentyl, adamantyl, norbornyl, etc.

[0045] From the viewpoint of easily obtaining friction reduction effect, the aliphatic hydrocarbon group with 4 or more carbon atoms is preferably a chain aliphatic hydrocarbon group, more preferably a straight-chain aliphatic hydrocarbon group, further preferably a straight-chain alkyl or straight-chain alkenyl group, and most preferably a straight-chain alkyl group.

[0046] Furthermore, from the viewpoints of friction reduction effect and ease of availability, the aliphatic hydrocarbon group with 4 or more carbon atoms preferably has 4 to 40 carbon atoms, more preferably 8 to 35, further preferably 10 to 30, even more preferably 12 to 25, and most preferably 15 to 20 carbon atoms. Typically, the larger the number of carbon atoms in the aliphatic hydrocarbon group, the more hydrophobic it is, the better its affinity with lubricating oil, and the easier it is to obtain a friction reduction effect. In addition, typically, the smaller the number of carbon atoms in the aliphatic hydrocarbon group, the easier it is to control costs.

[0047] The functional group and the aliphatic hydrocarbon group having 4 or more carbon atoms can be directly combined, or they can be combined through groups with a valence of 2 or more. Groups with a valence of 2 or more can also be represented by the following general formula, for example.

[0048] [Chemical Formula 1]

[0049] Here, n and m each independently represent an integer of 1 or more. n is preferably an integer from 1 to 4, more preferably 2 or 3, and even more preferably 2. m is preferably an integer from 1 to 10, more preferably an integer from 1 to 5, and most preferably an integer from 1 to 4. The group represented by the above general formula is particularly preferably an ethylene oxide unit.

[0050] The following are specific examples of compound A.

[0051] • Examples where the terminal functional group is a phosphate group: Lauryl phosphate, tetradecyl phosphate, myristyl phosphate, hexadecyl phosphate, stearyl phosphate, 9-octadecenyl phosphate, lauryl ether-2 phosphate, lauryl ether-3 phosphate, lauryl ether-4 phosphate, stearyl ether-2 phosphate, stearyl ether-3 phosphate, stearyl ether-4 phosphate, oleyl ether-2 phosphate, oleyl ether-3 phosphate, oleyl ether-4 phosphate, tri(2-ethylhexyl) phosphate, or their alkali metal salts, alkaline earth metal salts, or amine salts, etc. These can be diesters, monoesters, or mixtures of diesters.

[0052] • Examples where the terminal functional group is a hydroxyl group: 1-Dodecanool (laurate alcohol), 1-Tetradecanool (myristol), 1-Hexadecanool (cetyl alcohol), 1-Octadecanol (stearyl alcohol), 9-Octadecan-1-ol (oleyl alcohol), etc.

[0053] • Examples where the terminal functional group is a carboxyl group, a carboxylic acid ester group, or a carboxylic acid halide group: Saturated fatty acids such as valeric acid, caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, eicosanoic acid, and triacontanoic acid; ω-3 fatty acids such as α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid; ω-6 fatty acids such as linoleic acid and gamma-linolenic acid; ω-9 fatty acids such as oleic acid; dimer acids (C36 dicarboxylic acids); their methyl esters or 2,3-dihydroxypropyl esters (e.g., glyceryl monooleate); their alkali metal salts, alkaline earth metal salts, or amine salts; or their acyl halides (especially acyl chlorides), etc.

[0054] • Examples where the terminal functional group is an amide group: Laurylamide, hexadecylamide, stearylamide, octadecylamide, oleamide, isostearyl polyamide, etc.

[0055] • Examples of cases where the terminal functional group is amino: Dodecylamine (laurylamine), tetradecylamine (myristylamine), hexadecylamine (cetylamine), octadecylamine (stearylamine), 9-octadeceneamine (oleylamine), lauryl diethanolamine, myristyl diethanolamine, cetyl diethanolamine, stearyl diethanolamine, oleyl diethanolamine, etc.

[0056] The content of compound A in the rubber composition is not particularly limited. The content of compound A in the rubber composition is preferably 0.01 to 20 parts by mass relative to 100 parts by mass of the rubber composition, more preferably 0.1 to 15 parts by mass, and even more preferably 1 to 10 parts by mass.

[0057] (Inorganic filler) Rubber compositions may also contain inorganic fillers. When an inorganic filler is present in the rubber composition, compound A is adsorbed onto the filler, inhibiting its dissolution into the lubricating oil and thus maintaining a long-term friction-inhibiting effect.

[0058] The type of inorganic filler is not particularly limited; for example, at least one selected from the group consisting of carbon black, metal oxides, metal hydroxides, and silicate minerals can be used. Examples of metal oxides include iron(III) oxide (Fe₂O₃), chromium(III) oxide (Cr₂O₃), titanium dioxide (TiO₂), aluminum oxide (Al₂O₃), magnesium oxide (MgO), and zinc oxide (ZnO). Examples of metal hydroxides include magnesium hydroxide and aluminum hydroxide. Examples of silicate minerals include silica, wollastonite, talc, and mica.

[0059] In inorganic fillers, from the viewpoint of availability and adsorption to compound A, metal oxides, metal hydroxides or silicate minerals are preferred, with iron oxide (III), chromium oxide (III), titanium dioxide, aluminum hydroxide, silicon dioxide, wollastonite or talc being more preferred, iron oxide (III), chromium oxide (III), titanium dioxide, aluminum hydroxide or wollastonite being even more preferred, and iron oxide (III), chromium oxide (III), titanium dioxide or aluminum hydroxide being even more preferred.

[0060] The content of inorganic fillers in the rubber composition is not particularly limited. Relative to 100 parts by weight of the rubber composition, the content of inorganic fillers in the rubber composition is preferably 10 to 300 parts by weight, more preferably 20 to 250 parts by weight, further preferably 30 to 200 parts by weight, and most preferably 50 to 150 parts by weight.

[0061] (Other ingredients) In addition to the above components, rubber compositions may also include, as needed, various additives commonly used in the field of rubber compositions, such as anti-aging agents, plasticizers, crosslinking agents, crosslinking accelerators, acid acceptors, and processing aids.

[0062] (Method for manufacturing rubber composition and sealing component) The rubber composition is obtained by mixing the above components using a kneader or open mill. The sealing component can be obtained by forming the obtained rubber composition into strip or granular preforms using an extruder or similar means, followed by appropriate molding and vulcanization. When using an inorganic filler, compound A and the inorganic filler can be added to the rubber composition separately, or compound A can be pre-treated to adsorb onto the surface of the inorganic filler before adding the treated inorganic filler to the rubber composition.

[0063] [Sealing device] The sealing device of the present invention can be any sealing device used in vehicles, general machinery, and industrial machinery to seal gaps between rotating and stationary parts, gaps between reciprocating and stationary parts, etc. Examples of such sealing devices include, but are not limited to, engine seals, steering dust seals, bonded piston seals, transmission seals, differential side seals, universal joint seals, shock absorber seals, wheel hub seals, and valve stem seals.

[0064] Figure 6 This is a cross-sectional view of a sealing device 1 (oil seal) as an example of the present invention. The sealing device 1 is a generally annular device disposed between a shaft 2 and a housing 3. The sealing device 1 is fixed by fitting into a hole formed in the housing 3. The sealing device 1 has a sealing member 6 including a dustproof lip 4 and a sealing lip 5, a metal ring 7, and a spring 8. The sealing member 6 is formed of the aforementioned rubber composition. The sealing lip 5 slides in contact with the surface of the shaft 2, preventing leakage of the sealed object from the sealed object side 10 to the atmospheric side 9. The spring 8 pre-tightens the sealing lip 5 towards the shaft 2, increasing the pushing force of the sealing lip 5. The dustproof lip 4 prevents dust from entering from the atmospheric side 9.

[0065] It should be explained that Figure 6The sealing device 1 shown is always an example of the sealing device of the present invention. As described above, the sealing device of the present invention can be any other sealing device used in vehicles, general machinery, and industrial machinery to seal gaps between rotating parts and stationary parts, gaps between reciprocating parts and stationary parts, etc.

[0066] Compared to techniques that involve coating the surface of a sealing component, the sealing device of the present invention can be manufactured without cumbersome processes. Furthermore, since the rubber composition itself has friction-inhibiting properties, its effectiveness is easily maintained even under wear. Additionally, because the sealing device of the present invention does not select the surface shape of the sealing component, it can be directly applied to the structures of various existing sealing devices. Moreover, compared to techniques using self-lubricating rubber compositions, the sealing component of the sealing device of the present invention can inhibit friction even in the presence of a lubricant, inhibit the dissolution of components into the lubricant, and is not selective in terms of the type of rubber component. The friction-inhibiting effect of the sealing component of the sealing device of the present invention is independent of the rate of frosting or seepage, thus making friction control easier.

[0067] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and includes the concept of the present invention and all the ways contained in the claims. Various changes can be made within the scope of the present invention. Example

[0068] The present invention will be further described in detail below by way of examples, etc., but the present invention is not limited by these examples, etc.

[0069] [Experimental Conditions] (Dynamic friction test of molded parts using rubber composition) The rubber component, compound A, and inorganic filler were mixed using a kneader and an open mill, and then molded at 180°C for 6 minutes to obtain hemispherical rubber test pieces with a diameter of 5 mm. Dynamic friction tests were conducted using a reciprocating dynamic friction testing machine (manufactured by our company) under the following conditions.

[0070] Lubricating oil: mineral oil Load: 3N Temperature: 60℃ Speed: 0.01–10 mm / s (except for Test Example 2), 0.01 mm / s (Test Example 2) (Dynamic friction test using cold-rolled steel sheet (SPCC)) The surface of a 30mm × 50mm × 2mm cold-rolled steel sheet was coated with compound A. Dynamic friction tests were conducted using a reciprocating dynamic friction testing machine (manufactured by our company) under the following conditions.

[0071] Lubricating oil: mineral oil Load: 3N Temperature: 60℃ Speed: 0.01~10mm / s (Experimental Example 1 - The Influence of Rubber Components) As rubber components, rubber composition molded articles were manufactured using FKM (fluororubber, Solvay Technoflon P757), NBR (acrylonitrile-butadiene rubber, JSR Corporation N220S), and ACM (acrylic rubber, commercially available), respectively, and dynamic friction tests were conducted. For FKM, test pieces were used, which were obtained by using 5 parts by mass of compound A1 (described later as compound A) and 75 parts by mass of iron oxide (III) as an inorganic filler, relative to 100 parts by mass of FKM. For NBR, test pieces were used, which were obtained by using 9 parts by mass of compound A1 (compound A) and 140 parts by mass of iron oxide (III) as an inorganic filler, relative to 100 parts by mass of NBR. For ACM, test pieces were used, which were obtained by using a specified amount of compound A and a specified amount of inorganic filler, relative to ACM. Additionally, test pieces without compound A were manufactured as control groups. Figure 1 This represents the coordinate corresponding point relative to the coefficient of friction (dynamic friction coefficient) with respect to G (viscosity, velocity, contact width / tightness). It should be noted that multiple coordinate corresponding points relative to the same G indicate that multiple tests were conducted within that same G.

[0072] like Figure 1 As shown, even when using any of FKM, NBR, and ACM as the rubber component, the coefficient of friction of the composition containing compound A was significantly suppressed compared to the control group without compound A. The suppression effect on the coefficient of friction was particularly significant in the low-speed (low-G) region where boundary lubrication or mixed lubrication occurs.

[0073] (Experimental Example 2 - The Influence of Inorganic Fillers) Various rubber composition molded articles were obtained by using 5 parts by weight of various compounds A and 75 parts by weight of various inorganic fillers, relative to 100 parts by weight of FKM (fluororubber, Solvay Technoflon (registered trademark) P757). Dynamic friction tests were then conducted on these rubber composition molded articles. Additionally, test pieces without compound A were manufactured as control groups for each rubber composition. With a sliding speed fixed at 0.01 mm / s, a coefficient of friction less than 0.1 was evaluated as a, a coefficient of friction greater than 0.1 and less than 0.5 was evaluated as b, and a coefficient of friction greater than 0.5 was evaluated as c.

[0074] It should be noted that, as compound A, the following ashless friction modifiers, which are compounds A1 to A5, were used.

[0075] Compound A1: Glyceryl monooleate Compound A2: Oil-based diethanolamine Compound A3: Isostearyl polyamide Compound A4: Mono- and diacid oleyl phosphate ester amine salt (oleyl phosphate ester (mono- and diester mixture)) Compound A5: Stearyl alcohol polyether-3-phosphate In addition, the following substances were used as inorganic fillers.

[0076] Iron oxide (III): Brown #601 manufactured by Resin Color Industries, Ltd. Chromium oxide (III): Resin Color Industries, Ltd., STV-T-3466 Titanium dioxide: Tipaque A100 manufactured by Ishihara Sangyo Co., Ltd. Aluminum hydroxide: BF013 manufactured by Nippon Light Metals Co., Ltd. Wollastonite A: Wollastnite 1250 manufactured by Imerys Wollastonite B: Wollastnite 400 manufactured by Imerys Wollastonite C: NYCO Minerals, Inc. NYGLOS 4W Carbon Black A: Acetylene Black (Denka Black manufactured by Denka Kogyo Co., Ltd.) Carbon Black B: Carbon Black N330 (Showblack N330 manufactured by Showa Cabot Corporation) Carbon Black C: Carbon Black N990 (Thermax manufactured by Cancarb) Silica A: Tosoh Silica Co., Ltd., Nipsil E74P Silica B: Reolosil CP-102 manufactured by Tokuyama Corporation The results are shown in Table 1.

[0077] [Table 1]

[0078] As shown in Table 1, the coefficient of friction in the low-speed region (corresponding to boundary lubrication or mixed lubrication) was significantly suppressed by using compound A in a wide range of inorganic fillers.

[0079] (Experimental Example 3 - Effects of Functional Groups A) The surface of cold-rolled steel sheet (SPCC) was treated with stearamine, oleamide, stearic acid, or stearyl alcohol polyether-2-phosphate as compound A, and dynamic friction tests were performed. Cold-rolled steel sheet (SPCC) not treated with compound A was used as a control group. Figure 2 This represents the coordinates of the points corresponding to the coefficient of friction (dynamic friction coefficient) relative to the sliding speed (mm / s).

[0080] like Figure 2 As shown, a reduction in the friction coefficient was observed in the low-speed region (at least one of 0.01 mm / s and 0.1 mm / s) when using all compounds A with terminal functional groups. Furthermore, the effect was particularly significant when the terminal functional group was a phosphate group.

[0081] (Experimental Example 4 - Effects of Functional Groups B) Various rubber composition molded articles were obtained by using 5 parts by mass of stearamine, oleamide, stearic acid or stearyl alcohol polyether-2-phosphate as compound A, and 75 parts by mass of iron oxide (III) relative to 100 parts by mass of FKM (fluororubber, Solvay Technoflon (registered trademark) P757). Dynamic friction tests were performed on these rubber composition molded articles. Additionally, test pieces without compound A were prepared as a control group. Figure 3 This represents the coordinates of the points corresponding to the coefficient of friction (dynamic friction coefficient) relative to the sliding speed (mm / s).

[0082] like Figure 3 As shown, in the tests using rubber composition molded articles, a reduction in the coefficient of friction was also observed in the low-speed region (at least one of 0.01 mm / s and 0.1 mm / s) when using compound A with all terminal functional groups. Furthermore, regarding the type of functional group with particularly high effect, the same tendency as in Test Example 3 using cold-rolled steel sheet (SPCC) was observed.

[0083] As can be seen from the results of Experiments 3 and 4, the results obtained by using cold-rolled steel sheet (SPCC) are somewhat related to the results obtained by using rubber composition molded body. Therefore, various studies were conducted below using cold-rolled steel sheet (SPCC).

[0084] (Experimental Example 5 - The effect of the number of carbon atoms) The surface of cold-rolled steel sheets (SPCC) was treated with valeric acid, stearic acid, or beeswax acid as compound A, and dynamic friction tests were performed. Cold-rolled steel sheets (SPCC) not treated with compound A were used as a control group. Figure 4This represents the coordinates of the points corresponding to the coefficient of friction (dynamic friction coefficient) relative to the sliding speed (mm / s).

[0085] like Figure 4 As shown, when using compound A with a large number of aliphatic hydrocarbon groups, the effect of suppressing the friction coefficient in the low-speed region (corresponding to boundary lubrication or mixed lubrication) is more significant.

[0086] (Experimental Example 6 - The Effects of Structure) The surface of cold-rolled steel sheets (SPCC) was treated with either a branched compound (tris(2-ethylhexyl) phosphate) or a straight-chain compound (stearyl ether-2-phosphate) as compound A, and dynamic friction tests were performed. Cold-rolled steel sheets (SPCC) not treated with compound A were used as a control group. Figure 5 This represents the coordinates of the points corresponding to the coefficient of friction (dynamic friction coefficient) relative to the sliding speed (mm / s).

[0087] like Figure 5 As shown, when using compound A with a straight-chain structure, the effect of suppressing the friction coefficient in the low-speed region (corresponding to boundary lubrication or mixed lubrication) is more significant.

[0088] Industrial availability The sealing device and rubber composition of the present invention are suitable for use in the fields of vehicles, general machinery and industrial machinery to achieve sealing of gaps between rotating parts and stationary parts, gaps between reciprocating parts and stationary parts, etc.

Claims

1. A sealing device comprising a sealing member, the sealing member contains a rubber composition, the rubber composition contains a compound having a functional group at a terminal and an aliphatic hydrocarbon group having 4 or more carbon atoms.

2. The sealing device according to claim 1, wherein the rubber composition contains an inorganic filler.

3. The sealing device according to claim 2, wherein the inorganic filler is at least one or more selected from the group consisting of carbon black, metal oxide, metal hydroxide, and silicate mineral.

4. The sealing device according to claim 2 or 3, wherein the compound modifies a surface of the inorganic filler.

5. The sealing device according to any one of claims 1 to 3, wherein the functional group is a phosphoric acid group, a hydroxyl group, a carboxyl group, a carboxylate group, an amide group, or an amino group.

6. A rubber composition containing a compound having a functional group at a terminal and an aliphatic hydrocarbon group having 4 or more carbon atoms.

7. A method for improving lubricating oil retention of a sliding surface in a sealing device, which uses the rubber composition according to claim 6 for a sealing member.

8. A sealing device comprising a sealing member, the sealing member contains a rubber composition, the rubber composition contains an ashless friction modifier.

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