Lubricant composition

Abstract

The purpose of the present invention is to provide a lubricant composition that is excellent in coatability and lubricity and that serves as a replacement for a fluorine solvent-diluted lubricant composition. This lubricant composition is characterized by comprising: a solvent containing water or containing water and an organic solvent; a base oil; and an amide compound or metal soap as a thickener. Alternatively, this lubricant composition is characterized by comprising: a solvent containing water or containing water and an organic solvent; a base oil; and a thiazoline-based compound. Alternatively, this lubricant composition is characterized by comprising: a solvent containing water or containing water and an organic solvent; a base oil; resin particles as a solid lubricant; and / or inorganic particles having a cleavage structure.

Description

lubricating composition

[0001] This invention relates to water-dilutable lubricating compositions.

[0002] As described in the inventions of Patent Documents 1 and 2, fluorine solvent diluted lubricating compositions are known.

[0003] Fluorine solvent-diluted lubricating compositions are used by coating sliding parts of automobile parts, precision instruments, etc. with the aim of improving lubricity.

[0004] For example, a fluorine solvent diluted lubricating composition is prepared by dissolving or dispersing a fluorine oil as a base oil and a solid lubricant in a fluorine solvent.

[0005] JP 2020-105329 A JP 2010-184995 A

[0006] However, in applications where fluorine solvent-diluted lubricating compositions are used, the lubricity of fluorine solvent-diluted lubricating compositions is not necessarily high, as squeaking noises tend to occur at relatively high sliding speeds. Furthermore, fluorine compounds such as fluorine solvents are difficult to decompose, raising concerns about their impact on the environment. Therefore, the present invention has been made in consideration of the above problems, and aims to provide a lubricating composition that has excellent applicability and lubricity as an alternative to fluorine solvent-diluted lubricating compositions.

[0007] The lubricating composition of the present invention is characterized by containing water or a solvent containing water and an organic solvent, a base oil, and an amide compound or a metal soap as a thickener. In the present invention, the thickener preferably contains one or more fatty acid monoamides or fatty acid bisamides. The thickener preferably contains a fatty acid having 16 to 22 carbon atoms.

[0008] The lubricating composition of the present invention is characterized by comprising water or a solvent containing water and an organic solvent, a base oil, and a thiazoline-based compound.

[0009] In the present invention, the thiazoline compound preferably includes one or more of 1,2-benzothiazolin-3-one, 2-butyl-1,2-benzothiazolin-3-one, and 2-methyl-4-isothiazolin-3-one.

[0010] The lubricating composition of the present invention is characterized by comprising water or a solvent containing water and an organic solvent, a base oil, and resin particles and / or inorganic particles having a cleavage structure as a solid lubricant, and the proportion of the solid lubricant to the total amount of the base oil and the solid lubricant is preferably 5% by mass or more and 80% by mass or less.

[0011] In the present invention, the base oil preferably contains one or more of glycol oil, glycol derivative, sorbitan ester, and polyether-modified silicone oil.

[0012] In the present invention, it is preferable to use it as a lubricant for resins, metals, leather, or rubber, or as an insertion aid or mold release agent.

[0013] The lubricating composition of the present invention has excellent applicability and lubricity, and is also environmentally friendly because it is water-based.

[0014] An embodiment of the present invention (hereinafter abbreviated as "embodiment") will be described in detail below. Note that the present invention is not limited to the following embodiment, and can be practiced with various modifications within the scope of the gist. Furthermore, the expression "to" includes both the lower limit and the upper limit as a range.

[0015] <Background to the Invention of the Present Embodiment> Conventionally, lubricating compositions diluted with fluorine solvents have been used as lubricating compositions to be applied to sliding parts of automobile parts, precision instruments, etc. The properties required of lubricating compositions are good slipperiness, little generation of squeaking noise, and excellent durability.

[0016] However, in a reciprocating sliding test using a fluorine solvent-diluted lubricating composition, when the number of sliding cycles was limited to 10,000 or less, it was confirmed that the first abnormal noise was observed after several hundred sliding cycles. Furthermore, the solid lubricant contained in the fluorine solvent-diluted lubricating composition peeled off due to sliding, reducing durability and making the composition more susceptible to abnormal noise.

[0017] Therefore, the present inventors have focused on water-diluted lubricating compositions instead of fluorine solvent-diluted lubricating compositions, and by optimizing the lubricating components to be diluted in the water-based solvent, have developed a lubricating composition with excellent application properties and lubricity.

[0018] <Lubricating Composition of First Embodiment> The lubricating composition of the first embodiment contains water or a solvent containing water and an organic solvent, a base oil, and an amide compound or a metal soap as a thickener.

[0019] (Solvent) The lubricating composition of the present embodiment contains water as a solvent as an essential component. The content of the solvent is not limited, and any amount is acceptable as long as it can dilute the lubricating components. For example, when only water is used as the solvent, the content is preferably 70% by mass or more and 99% by mass or less, and more preferably 80% by mass or more and 98% by mass or less, when the total mass of the lubricating composition is 100% by mass.

[0020] In this embodiment, the solvent may contain only water, or may be a mixture of water and an organic solvent. The organic solvent is not particularly limited as long as it is soluble or dispersible in water, but as an example of the index, it is preferable to use an organic solvent with a solubility parameter (hereinafter referred to as SP value) of 9 or more. Here, "dispersed" means that the material is dispersed for 5 minutes or more when shaken by hand.

[0021] There are no limitations on the type of organic solvent, as long as it has an SP value of 9 or greater, but for example, alcohols and glycols are preferably used. Examples of organic solvents with an SP value of 9 or greater include ethyl acetate (SP value of about 9), acetone (SP value of about 10), methyl cellosolve (SP value of about 10), and ethanol (SP value of about 13), which can be used by mixing with water. Incidentally, the SP value of water is about 23.

[0022] The solvent containing the organic solvent and water is not limited in content, and the amount is not limited as long as it can dilute the lubricating components, but is preferably 70% by mass or more and 99% by mass or less, and 80% by mass or more and 98% by mass or less, when the total lubricating composition is 100% by mass. The organic solvent alone is about 20% by mass to 60% by mass. From the viewpoint of safety, when alcohol is used as the organic solvent, the amount is preferably less than 60% by mass, more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0023] (Base Oil) The base oil is an essential component as a lubricating component, and is a surfactant that can be dissolved or dispersed in water, or temporarily dispersed by stirring. It is preferable that the base oil in this embodiment does not contain fluorinated oil, which is difficult to decompose in the environment.

[0024] The kinematic viscosity of the base oil is 20 mm within the temperature range of 20 to 30°C. ２ / s~1500mm ２ When a plurality of base oils are mixed, the kinematic viscosity of each base oil is adjusted within the above range.

[0025] The base oil preferably contains one or more of glycol oil, glycol derivative, sorbitan ester, and polyether-modified silicone oil.

[0026] Examples of glycol oils that can be used include, but are not limited to, polyoxyalkylene monobutyl ether, polyoxyethylene alkyl ether, and polyoxyethylene polyoxypropylene glycol. Examples of glycol derivatives that can be used include polyalkylene glycol derivatives and acetylene glycol derivatives. Examples of sorbitan esters that can be used include sorbitan monocaprylate.

[0027] The content of the base oil is not limited, but is preferably 1% by mass to 25% by mass, and more preferably 1% by mass to 18% by mass, when the total amount of the lubricating composition is 100% by mass. When multiple types of base oils are mixed, the total amount is adjusted to be within the above content range.

[0028] (Thickener) In the first embodiment, an amide compound or a metal soap is contained as a thickener as an essential component. By mixing the thickener, it is possible to improve lubricity.

[0029] The reason why adding a thickener improves lubricity is thought to be that the thickener turns the material into a semi-solid state when mixed in, forming a strong coating that makes it less likely for the coating to peel off or components to leak out due to a decrease in durability caused by sliding.

[0030] Either an amide compound or a metallic soap, or both, may be mixed in. The thickener preferably contains one or more of fatty acid monoamides or fatty acid bisamides.

[0031] Examples of fatty acid monoamides include monopalmitic acid amide (carbon number: 16), monostearic acid amide (carbon number: 18), monobehenic acid amide (carbon number: 22), monooleic acid amide (carbon number: 18), monoerucic acid amide (carbon number: 22), etc. The number of carbon atoms of the fatty acid is 16 to 22.

[0032] Examples of fatty acid bisamides include ethylene bispalmitic acid amide, ethylene bisstearic acid amide, ethylene bisbehenic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, methylene bisstearic acid amide, etc. The number of carbon atoms of the fatty acid is 16 to 22, and the fatty acid bisamide has two added fatty acids.

[0033] Although not limited thereto, examples of metallic soaps include zinc stearate (preferably zinc hydroxystearate), Ca soap, Li soap, and the like.

[0034] The content of the thickener is not limited, but is preferably 0.01% by mass or more and 7% by mass or less, and more preferably 0.01% by mass or more and 3% by mass or less, when the entire lubricating composition is taken as 100% by mass.

[0035] In the first embodiment, the solvent may be contained in an amount of 70% by mass to 99% by mass, the base oil in an amount of 1% by mass to 25% by mass, and the thickener in an amount of 0.01% by mass to 7% by mass.

[0036] <Lubricating Composition of Second Embodiment> The lubricating composition of the second embodiment contains water or a solvent containing water and an organic solvent, a base oil, and a thiazoline-based compound.

[0037] The solvent and base oil used in the lubricating composition of the second embodiment are the same as those mixed in the lubricating composition of the first embodiment, so please refer to the (Solvent) and (Base Oil) sections above.

[0038] (Thiazoline Compound) In the present embodiment, a thiazoline compound is contained as an essential component. Thiazoline compounds are used as antiseptics, and by mixing a thiazoline compound, it is possible to improve lubricity as well as the antiseptic effect.

[0039] The reason why the addition of thiazoline compounds improves lubricity is thought to be that an adsorption film is formed, which reduces the coefficient of friction, although this is merely speculation.

[0040] Although not limited thereto, the thiazoline compound preferably includes one or more of 1,2-benzothiazolin-3-one, 2-butyl-1,2-benzothiazolin-3-one, and 2-methyl-4-isothiazolin-3-one. Multiple different types of thiazoline compounds may be mixed. For example, 1,2-benzothiazolin-3-one and 2-methyl-4-isothiazolin-3-one may be mixed. This allows for a synergistic antiseptic effect to be achieved.

[0041] The content of the thiazoline compound is not limited, but is preferably 0.0001% by mass or more and 5% by mass or less, and more preferably 0.001% by mass or more and 2% by mass or less, when the total lubricating composition is taken as 100% by mass. The content of the thiazoline compound is preferably less than the content of the base oil. The content of the thiazoline compound can be half or less of the content of the base oil.

[0042] In the second embodiment, the solvent may be contained in an amount of 70% by mass to 99% by mass, the base oil in an amount of 1% by mass to 25% by mass, and the thiazoline compound in an amount of 0.0001% by mass to 5% by mass.

[0043] <Other Components> The lubricating composition of the first embodiment can be composed only of a solvent, a base oil, and a thickener, and the lubricating composition of the second embodiment can be composed only of a solvent, a base oil, and a thiazoline-based compound, but can also contain other components.

[0044] As other components, for example, the thiazoline compound contained in the second embodiment can be mixed with the lubricating composition of the first embodiment. That is, a lubricating composition can be obtained by diluting lubricating components including a base oil, a thickener, and a thiazoline compound with an aqueous solvent. By including a thiazoline compound in the lubricating composition of the first embodiment, the effect of mixing the thickener is to shorten the drying time of the coating film and improve work efficiency, while the effect of mixing the thiazoline compound is to improve antiseptic properties. In this case, the content of the thiazoline compound is not limited, but is preferably about 0.0001% by mass or more and 5% by mass or less when the entire lubricating composition is taken as 100% by mass.

[0045] <Lubricating Composition of Third Embodiment> The lubricating composition of the third embodiment contains water or a solvent containing water and an organic solvent, a base oil, and a solid lubricant.

[0046] The solvent and base oil used in the lubricating composition of the third embodiment are the same as those mixed in the lubricating composition of the first embodiment, so please refer to the (Solvent) and (Base Oil) sections above.

[0047] (Solid Lubricant) In the third embodiment, a solid lubricant is included as an essential component. The solid lubricant includes resin particles and / or inorganic particles having a cleavage structure. While the resin particles are not limited, it is preferable to include one or more of melamine cyanurate, polytetrafluoroethylene, polyethylene, olefin resin, and urethane resin. Examples of inorganic particles having a cleavage structure include molybdenum disulfide, organic molybdenum, carbon black, and boron nitride. By incorporating a solid lubricant, smoothness can be improved and lubricity can be enhanced. In particular, the inclusion of resin particles and / or inorganic particles having a cleavage structure can reduce stickiness after application and drying to parts, and can provide excellent rubber lubricity and reduced frictional force after drying. However, if the content of the solid lubricant is too high, the solid lubricant will peel off from the coating surface as the number of sliding movements increases, leading to increased friction. Therefore, the content of the solid lubricant is about 0.001 to 15 mass % of the total lubricating composition, preferably 0.001 to 5 mass %, more preferably 0.001 to 3 mass %, and even more preferably about 0.5 to 1 mass %.

[0048] The proportion of the solid lubricant relative to the total amount of the base oil and the solid lubricant is preferably 5% by mass or more and 80% by mass or less, and more preferably 15% by mass or more and 65% by mass or less. The proportion of the solid lubricant can be determined from the base oil and the solid lubricant in the lubricating composition, or can be determined from the proportion of the base oil and the solid lubricant remaining after the solvent, which is the main component, has evaporated during drying.

[0049] The addition of a solid lubricant may cause the coating film to take on a color. On the other hand, if no solid lubricant is mixed, the coating film can be transparent or nearly transparent. Therefore, the addition of a solid lubricant can be selected depending on the application of the lubricating composition of this embodiment. For example, in applications where the lubricating composition is applied to a location that is not visible from the outside and transparency is not required, adding a solid lubricant to the lubricating composition to color the coating film makes it possible to identify the presence of the coating film and improve work efficiency. For example, in the automotive part application described below, mixing a solid lubricant to color the coating film makes it easy to check whether the coating is applied even in a location that is difficult to see, and makes it easy to prevent forgetting to apply the coating. In addition, the color allows the user to roughly grasp the amount of coating, making it easier to ensure the desired lubrication performance.

[0050] A solid lubricant may also be added to the lubricating composition of the first embodiment and / or the second embodiment.

[0051] Furthermore, if necessary, antioxidants, rust inhibitors, oiliness agents, anti-wear agents, extreme pressure agents, etc. can be added to the lubricating composition of this embodiment. The total content of these additives is within the range of approximately 0.001% by mass to 25% by mass of the total. When the above-mentioned solid lubricant is also mixed, it is preferable to adjust the total content of the additives, including the solid lubricant, to approximately 0.001% by mass to 25% by mass.

[0052] Antioxidants can be selected from hindered phenols, triphenols, alkylated diphenylamines, ascorbic acid, phenyl-α-naphthylamine, etc. Rust inhibitors can be selected from sodium nitrite, carboxylic acids such as stearic acid, dicarboxylic acids, metal soaps, amine carboxylic acid salts, metal salts of heavy sulfonic acids, partial carboxylic acid esters of polyhydric alcohols, benzotriazole, etc. Oiliness agents can be selected from amines such as laurylamine, higher alcohols such as myristyl alcohol, higher fatty acids such as palmitic acid, fatty acid esters such as methyl stearate, and amides such as oleylamide. Antiwear agents can be selected from zinc-based, sulfur-based, phosphorus-based, amine-based, or ester-based agents. Extreme pressure agents can be selected from zinc dialkyldithiophosphates, molybdenum dialkyldithiophosphates, sulfurized olefins, sulfurized oils and fats, etc.

[0053] <Effects of Using the Lubricating Composition of the Present Embodiment> By using the lubricating composition of the present embodiment in sliding parts, it is possible to improve the sliding property, reduce creaking noise, and further improve durability. In addition, since the main component is water, it is environmentally friendly.

[0054] The lubricating composition of the present embodiment is obtained by diluting the lubricating components with an aqueous solvent, and does not decompose and release components that may have adverse effects on the environment, as is the case with fluorine solvent-diluted lubricating compositions, making it possible to provide an environmentally friendly lubricating composition.

[0055] The lubricating composition of the present embodiment can be applied to sliding spaces between, for example, resin-resin, resin-rubber, resin-metal, rubber-metal, rubber-rubber, rubber-leather, leather-leather, leather-resin, or leather-metal to improve the lubricity between the two components. Improved lubricity improves sliding, suppresses the generation of creaking noise, and further improves durability.

[0056] This improvement in lubricity is presumably due to the fact that the thickener, thiazoline compound, or solid lubricant added as a lubricating component forms a strong coating, which allows the lubricating component to spread throughout the entire coating film, preventing film peeling even over long periods of time and with many sliding movements, and allowing the coating film to be maintained in an appropriate state.

[0057] Regarding squeaking noise, for example, in the case of conventional fluorine-containing solvent-diluted lubricating compositions, the mixed fluorine-containing solid lubricant tends to peel off from the coating surface as the number of sliding cycles increases, which is believed to be the cause of the noise. Even when a water-based solvent is used, if the lubricating components are not optimized, the coating peels off at an early stage of sliding cycles, and squeaking noise is observed. In contrast, the lubricating composition of the present embodiment contains, in addition to the base oil as a lubricating component, a thickener and a thiazoline-based compound that are easily absorbed by components, which can solve problems such as particle release and coating peeling that cause squeaking noise, and as a result, it is possible to suppress the generation of squeaking noise. As a result, durability and smoothness can be further improved, and the generation of squeaking noise can be appropriately suppressed.

[0058] The lubricating composition of the present embodiment is also effective as an insertion aid for rubber such as grommets, hoses, and seal materials.

[0059] In other words, when passing cables or tubes through rubber or fitting rubber as a sealing material into parts, if nothing is applied, the friction is too high and insertion is impossible. Generally, there is a demand for the use of fluorine solvent-diluted lubricants, oils such as mineral oil and glycol oil, and organic solvents as insertion aids to make insertion easier.

[0060] Fluorine solvent diluted lubricants have problems such as the need for force to insert them and their high price.

[0061] Furthermore, while conventional oils and organic solvents can improve insertion, there are concerns that they may cause the rubber to swell, making it easier to remove, or that the durability of the rubber may deteriorate. Additionally, there is also concern that oils may be sticky and transfer to the surrounding area of ​​the part, causing contamination.

[0062] In contrast, in this embodiment, since water is the main component, swelling and deterioration of the rubber can be suppressed, resulting in excellent insertability. Furthermore, when the water dries after application, the active ingredient decreases, so it is possible to suppress the rubber from coming off and also to suppress stickiness.

[0063] Let's consider further the use of rubber lubrication. For example, there are applications where friction is reduced only immediately after application, such as when pressing in a hose, but there are also cases where lubrication is required even after application and drying, such as when applying to grommets. For example, there are cases where the timing of assembly into a vehicle requires applying lubricant to the part and then waiting for a while before fitting the part.

[0064] Conventionally, for example, oil has been applied to the parts to make them slippery, but this can cause stickiness and oil dripping, which can contaminate surrounding parts.

[0065] In particular, the experiments described below have shown that the inclusion of a solid lubricant in the lubricating composition of the third embodiment can suppress stickiness after application and drying. That is, after drying, the lubricating composition can suppress stickiness and reduce frictional force. It is also effective as a rubber lubricant.

[0066] <Applications> Although the applications are not limited thereto, the lubricating composition of the present embodiment can be used for lubricating interior parts of automobiles, precision instruments, ballpoint pens, and interior building materials, for example, as an insertion aid, a release agent, or a rubber lubricant. Here, in the present embodiment, the lubricating composition can be used both in applications where at least a portion of the solvent remains after application to the parts, and in applications where the lubricating composition has been applied to the parts and dried. Examples of automobile interior parts include seats, weatherstrips, grommets, etc. Examples of precision instruments include cameras, etc. Among these, the lubricating composition is particularly preferably used in automobile interior parts.

[0067] The present invention will be described in detail below with reference to examples carried out to clarify the effects of the present invention, but the present invention is not limited to the following examples.

[0068] The following Comparative Examples 1 to 3 and Examples 1 to 18 were prepared. The raw materials used in each sample are as shown in Tables 1 and 2.

[0069] Comparative Example 1 is a fluorine solvent diluted lubricating composition. Comparative Examples 2 and 3 are water diluted lubricating compositions, but contain only base oil other than water.

[0070] Examples 1 to 9 are water-dilutable lubricating compositions containing a base oil and a thickener as lubricating components. Examples 11 to 18 are water-dilutable lubricating compositions containing a base oil and a thiazoline compound as lubricating components. Example 10 contains a base oil, a thiazoline compound, and a thickener as lubricating components.

[0071] The content of each component in each sample is shown in units of mass % in Tables 1 and 2. In the experiment, each sample was prepared by mixing the components shown in Tables 1 and 2, and the application property and lubricity were examined.

[0072] [Coatability] The lubricating composition of each sample was applied once to the surface of a polyacetal (POM) plate with a brush. After drying for one day, the coating film was checked for unevenness. If the coating film had no unevenness, it was marked ○. If the unevenness was particularly small (the surface had little unevenness), it was marked ⊚. The presence or absence of unevenness and its quality could be observed by light reflection.

[0073] [Lubricity] After the above-mentioned coatability test was completed, a reciprocating sliding test was carried out by butting a 4 mm diameter polyacetal pin against the surface of the coating film with a load of 100 g, with a sliding distance of 10 mm, a sliding speed of 20 mm / s, and a number of sliding movements of 10,000.

[0074] In the reciprocating sliding test, whether or not abnormal noise occurred was observed during 10,000 sliding cycles, and the number of sliding cycles at which the abnormal noise first occurred was determined. If no abnormal noise occurred up to 10,000 sliding cycles, the result was marked as ○. The average coefficient of friction after 10,000 sliding cycles was also determined.

[0075] [Insertion / Removal Test] In this experiment, an ethylene propylene rubber (EPDM) hose / polyvinyl chloride (PVC) tube insertion / removal test was conducted using an EPDM hose (inner diameter: 15 mm, outer diameter: 35 mm, hose length: 100 mm) and a PVC tube (inner diameter: 12 mm, outer diameter: 18 mm, hose length: 300 mm).

[0076] In the experiment, 10 mL of each lubricating composition sample was applied to the inside of an EPDM hose, and then the PVC tube was manually inserted into the EPDM hose for evaluation. If the PVC tube could be inserted, it was marked with a circle, and if it could not be inserted, it was marked with an X.

[0077] The next day after application, the PVC tube was evaluated for whether it could be pulled out of the EPDM hose when pulled by hand. If it could be pulled out, it was marked with "x", and if it could not be pulled out, it was marked with "o".

[0078]

[0079]

[0080] First, in terms of coatability, there was no unevenness in either the Examples or the Comparative Examples, and no significant difference was observed. However, in Examples 1 to 10, in which a thickener was added, the waviness of the coating film surface was smaller than in Examples 11 to 18, demonstrating superior coatability. The addition of a thickener shortened the drying time, allowing for a cleaner coat.

[0081] Next, lubrication will be considered. First, in all of Comparative Examples 1 to 3, abnormal noise was observed after several hundred to several thousand reciprocating movements out of 10,000. The abnormal noise was measured by an observer, who listened to the noise (vibration) caused by stick-slip. On the other hand, in Examples 1 to 18, no abnormal noise was observed even once during the 10,000 reciprocating movements.

[0082] It was also found that the average friction coefficients of Examples 1 to 18 were smaller than the average friction coefficients of Comparative Examples 1 to 3. The average friction coefficients of Examples 1 to 18 were approximately 0.08 to 0.20. In contrast, the average friction coefficient of Comparative Example 1, which was a fluorine solvent-diluted lubricating composition, was 0.31, and in some samples, this was more than twice as large as that of the Examples.

[0083] Next, the insertion / withdrawal test will be considered. Comparative Example 1 required a lot of force to insert, and could not be inserted.

[0084] On the other hand, in Comparative Examples 2 and 3 and Examples 1 to 18, excellent insertion and removal results were obtained.

[0085] [Regarding Examples 1 to 9] Examples 1 to 9 contain a base oil and a thickener as lubricating components. The addition of a thickener can more effectively improve application properties. An amide compound or a metal soap can be used as the thickener. In particular, it was found that the addition of a bisamide compound can more effectively improve lubricity and reduce the average coefficient of friction.

[0086] The desired lubricity effect can be obtained with a thickener content of about 10% by mass or less. Although increasing the thickener content can improve lubricity, it may have the disadvantage of making the components too hard and reducing productivity. Therefore, the thickener content is set to 7% by mass or less, and preferably 3% by mass or less.

[0087] The base oil is contained in a larger amount than the thickener, specifically, the base oil content is about 3% to 15% by mass. The base oil is the main component of the coating film, so it is contained in a large amount. By mixing a thickener into the base oil to further improve lubricity, a strong coating film is formed, and it is possible to dramatically suppress the generation of abnormal noise compared to Comparative Examples 1 to 3, and it has been found that the smoothness is improved.

[0088] As in Example 8, it is possible to mix an organic solvent with water as the solvent.

[0089] [Regarding Examples 11 to 18] Examples 11 to 18 contain a base oil and a thiazoline compound as lubricating components. The thiazoline compound has both an antiseptic effect and an effect of improving lubricity. Therefore, by including the thiazoline compound, it is possible to further improve durability.

[0090] The desired lubricity effect can be obtained with a thiazoline compound content of 1% by mass or less. Although increasing the thiazoline compound content can improve lubricity, it may have the disadvantage of being more prone to precipitation. Therefore, the thiazoline compound content is set to 5% by mass or less, preferably 2% by mass or less, and more preferably 1% by mass or less.

[0091] The base oil is contained in a larger amount than the thiazoline compound, specifically, the base oil content is about 3% to 13% by mass. The base oil as an oil component is the main component of the coating film, so it is contained in a large amount. By mixing a thiazoline compound that forms an adsorption coating into the base oil to further improve lubricity, it was found that the generation of abnormal noise can be dramatically suppressed compared to Comparative Examples 1 to 3, and smoothness is improved.

[0092] In Examples 11 to 18, only water was used as the solvent, but an organic solvent such as an alcohol or glycol solvent may also be mixed with water.

[0093] [Regarding Example 10] Example 10 contains a base oil, a thickener, and a thiazoline compound as lubricating components. In Example 10, the addition of the thickener provides the benefit of shortening the drying time of the coating film and improving work efficiency, while the addition of the thiazoline compound provides the benefit of improving antiseptic properties.

[0094] [Drying property] The results of an experiment on drying property are shown in Table 3. In the experiment, 0.5 mL of each lubricating composition shown in Table 3 was placed in a metal dish (opening diameter: 73 mm), and the dish was allowed to stand at room temperature of about 22°C and humidity of about 30%, and the end point of the weight change was taken as the drying time.

[0095] As shown in Table 3, Comparative Example 4 contains only water. Examples 4, 6, and 13 are lubricating compositions used in the experiments in Tables 1 and 2. Example 19 is a lubricating composition containing water, a base oil, a thiazoline compound, and a solid lubricant. Example 20 is a lubricating composition containing water, a base oil, a thickener, and a thiazoline compound.

[0096]

[0097] In Examples 4, 6, 13, 19, and 20, the drying time was shorter than in Comparative Example 4. In each Example, the action of a surfactant such as polyoxyethylene alkyl ether caused the coating to spread into a thin film, which is thought to increase the specific surface area and allow the coating to dry faster than water.

[0098] Furthermore, as in Examples 4, 6, and 20, it was found that the inclusion of a thickener effectively shortened the drying time.

[0099] [Experiments using lubricating compositions containing solid lubricants] The following Comparative Examples 5 to 8 and Examples 21 to 33 were prepared. The raw materials used in each sample are as shown in Table 4.

[0100] In Comparative Example 5, no lubricant was applied in the reciprocating sliding test. In Comparative Examples 6 and 7, a lubricating composition containing only base oil was used. In Comparative Example 8, a lubricating composition containing water, base oil, silica, and a thiazoline compound was used.

[0101] In Examples 21 to 33, lubricating compositions containing at least water, a base oil, and a solid lubricant were used. The solid lubricant used in the examples was resin particles or inorganic particles having a cleavage structure. The silica used in Comparative Example 8 does not fall under the category of inorganic particles having a cleavage structure.

[0102] [Coatability] Each lubricant was applied to EPDM rubber once with a brush, and after drying for one day, the coating film was checked for unevenness. If the coating film had no unevenness, it was marked ○. If the unevenness was particularly small (the surface had minimal irregularities), it was marked ⊚. The presence or absence of unevenness and its quality could be observed by light reflection.

[0103] [Lubricity] After the above-mentioned coatability test was completed, a SUS pin (φ4 mm) was butted against the EPDM rubber under a load of 500 g, and a reciprocating sliding test was performed with a sliding distance of 10 mm, a sliding speed of 20 mm / s, and 10 sliding cycles. The coefficient of friction was obtained as the average value of the static friction coefficients for the 10 sliding cycles.

[0104] [Stickyness] After the above-mentioned coating property test was completed, the stickiness of the coating surface was checked. If there was stickiness, it was marked with "x", and if there was no stickiness, it was marked with "o". The experimental results are shown in Tables 4 and 5 below.

[0105]

[0106]

[0107] As shown in Table 4, Comparative Examples 6 and 7, which contained only base oil, were evaluated as "×" for stickiness. In other words, commonly used oils are difficult to apply as a thin film and are very sticky. Furthermore, Comparative Example 8, which contained silica, showed a high friction coefficient and poor lubricity.

[0108] In contrast, it was found that the coefficient of friction could be reduced in Examples 21 to 33. Furthermore, stickiness could be suppressed in Examples 21 to 33.

[0109] For example, when lubricating grommets, it is required that the lubricant maintain good lubricity even after drying. What is required is that the lubricant is not sticky after drying and that frictional force can be reduced. In the lubricity tests shown in Tables 4 and 5, the lubricating composition was applied to rubber, dried, and then subjected to a sliding test using a metal pin. In the comparative examples, either stickiness or frictional force was evaluated as "NG."

[0110] [Regarding Examples 21 to 33] Examples 21 to 33 contain a base oil and a solid lubricant as lubricating components. It was found that these compositions can suppress stickiness while also reducing frictional force. In particular, they have been found to have excellent rubber lubrication properties.

[0111] In each example, resin particles or inorganic particles having a cleavage structure were contained as the solid lubricant, which was found to be able to suppress stickiness and reduce frictional force at the same time.

[0112] The content of the solid lubricant relative to the total amount of the base oil and the solid lubricant is preferably 5% by mass or more and 80% by mass or less, and more preferably 15% by mass or more and 65% by mass or less.

[0113] The lubricating composition of the present invention is water-based, environmentally friendly, and can be preferably applied to sliding parts of automobile parts and precision instruments. Use of the lubricating composition of the present invention can improve smoothness, reduce creaking noise, and further improve durability. In addition, stickiness after application and drying of the lubricant can be suppressed. Therefore, it is possible to obtain high-quality lubricating performance that also takes safety into consideration for the above-mentioned automobile parts and precision instruments.

[0114] This application is based on Japanese Patent Application No. 2023-185020, filed on October 27, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A lubricating composition comprising: water or a solvent containing water and an organic solvent; a base oil; and an amide compound or a metal soap as a thickener.

2. The lubricating composition according to claim 1, characterized in that the thickener contains at least one of fatty acid monoamides and fatty acid bisamides.

3. The lubricating composition according to claim 1, wherein the thickener contains a fatty acid having 16 to 22 carbon atoms.

4. A lubricating composition comprising: water or a solvent containing water and an organic solvent; a base oil; and a thiazoline compound.

5. The lubricating composition according to claim 4, characterized in that the thiazoline compound includes one or more of 1,2-benzothiazolin-3-one, 2-butyl-1,2-benzothiazolin-3-one, and 2-methyl-4-isothiazolin-3-one.

6. A lubricating composition comprising: water or a solvent containing water and an organic solvent; a base oil; and resin particles and / or inorganic particles having a cleavage structure as a solid lubricant.

7. The lubricating composition according to claim 6, characterized in that the ratio of said solid lubricant to the total amount of said base oil and said solid lubricant is 5 mass % or more and 80 mass % or less.

8. The lubricating composition according to claim 1, claim 4 or claim 6, characterized in that the base oil contains one or more of glycol oil, glycol derivative, sorbitan ester and polyether modified silicone oil.

9. The lubricating composition according to claim 1, 4 or 6, characterized in that it is used as an insertion aid, a mold release agent or a rubber lubricant.

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