Solvent-diluted aqueous lubricant composition

Abstract

To provide a solvent-dilutable water-based lubricant composition that can effectively disperse hydrophobic base oils such as perfluoropolyether oil and synthetic hydrocarbon oil, which constitute the grease, in water, which is the solvent, thereby forming a uniform grease film and providing good lubrication. [Solution] The present invention is a solvent-dilutable aqueous lubricating composition containing water as a solvent, a base oil dispersed in the solvent water and containing one or more selected from perfluoropolyether oil and synthetic hydrocarbon oil, a thickener, an additive containing a high molecular weight polysaccharide.

Description

Technical Field

[0001] The present invention relates to a solvent-diluted aqueous lubricant composition obtained by dispersing grease in water.

Background Art

[0002] Grease is often classified by base oil and thickener. Among them, grease obtained by thickening perfluoropolyether oil with a fluorine-based polymer such as polytetrafluoroethylene or an inorganic thickener is called fluorine grease. And a liquid lubricant in which the fluorine grease is dispersed in a fluorine-based solvent such as hydrofluoroether or hydrofluorocarbon is called a solvent-diluted fluorine-based lubricant.

[0003] In addition, a liquid lubricant in which grease is dispersed in water using water as a solvent with respect to a solvent-diluted fluorine-based lubricant dispersed in a fluorine-based solvent is called a solvent-diluted aqueous lubricant.

[0004] Fluorine grease is a grease having many excellent functions such as lubricity, heat resistance, oxidation stability, resin compatibility, rubber compatibility, low dust generation property, and chemical resistance due to its excellent performance derived from its base oil. Fluorine grease is particularly often used in precise and delicate parts such as home appliances. Although some home appliances may be handled without maintenance for more than 10 years depending on the product, fluorine grease can sufficiently satisfy the required specifications due to its multifunctionality. On the other hand, fluorine grease is also expensive. Therefore, it is required to be used in as thin a film as possible within the range where there are no problems in use.

[0005] Solvent-diluted fluorine-based lubricants form a thin fluorine grease film after application as the solvent evaporates. This reduces the amount of fluorine grease used, lowering costs. Furthermore, because solvent-diluted lubricants are low-viscosity liquid lubricants, they can be applied by methods such as dipping or brushing, improving work efficiency and productivity, and making application to parts with complex structures relatively easy. In addition, solvent-diluted lubricants have excellent fluidity, making it easy to control the dispersibility of fluorine grease in the solvent by using additives as needed, allowing for proper distribution of fluorine grease. As a result, the fluorine grease film after drying is a thin, uniform film with little variation, which in turn reduces the production cost of parts that form the fluorine grease film.

[0006] Recently, there has been a movement to regulate PFAS (perfluoroalkyl compounds and polyfluoroalkyl compounds, a general term for organofluorine compounds in which multiple fluorine atoms are bonded to an alkyl chain). Therefore, in solvent-diluted fluorine-based lubricants, there is a need for substitutes for the base oil perfluoropolyether oil, the solid lubricant polytetrafluoroethylene, and the fluorine-based solvents hydrofluoroether and hydrofluorocarbon. In particular, the replacement of fluorine solvents, which are present in large quantities in the composition, is an urgent matter.

[0007] For example, Patent Document 1 discloses a technology for a lubricant composition containing a lubricating oil, wax, melamine cyanurate, anionic surfactant, and aqueous solvent. The technology disclosed in Patent Document 1 states that by using an anionic surfactant in a lubricant composition containing an aqueous solvent, the sedimentation and separation of components such as solid lubricants can be reduced without using expensive fluorinated solvents and fluorinated oils.

[0008] However, even with the technology disclosed in Patent Document 1, for example, when using a highly hydrophobic lubricating oil, it may not be possible to sufficiently disperse the hydrophobic oil in the lubricant composition, and as a result, the formed grease film may not be uniform, and sufficient lubrication may not be guaranteed. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2008-88297 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] This invention was proposed in view of the above-mentioned conventional circumstances, and aims to provide a solvent-diluted aqueous lubricant composition, which is obtained by dispersing grease in water, that can form a uniform grease film and provide good lubricity. [Means for solving the problem]

[0011] The inventors diligently conducted research to solve the above-mentioned problems. As a result, they discovered that by including high-molecular-weight polysaccharides as additives in a solvent-diluted aqueous lubricant composition in which grease is dispersed in water, the hydrophobic base oil constituting the grease can be effectively dispersed in water, thus completing the present invention.

[0012] (1) The first invention of the present invention is a solvent-diluted aqueous lubricating composition comprising water as a solvent, a base oil dispersed in the water as a solvent and containing one or more selected from perfluoropolyether oil and synthetic hydrocarbon oil, a thickener, an additive containing a high molecular weight polysaccharide.

[0013] (2) The second invention of the present invention is a solvent-dilutable aqueous lubricant composition in which, in the first invention, the polymer polysaccharide forms a network structure by hydrogen bonding in water.

[0014] (3) The third invention of the present invention is a solvent-dilutable aqueous lubricant composition in which, in the first or second invention, the thickener comprises one or more selected from solid powders of polytetrafluoroethylene, melamine cyanurate, and polyethylene.

[0015] (4) The fourth invention of the present invention is a solvent-dilutable aqueous lubricant composition that further contains a surfactant in any of the first to third inventions.

[0016] (5) The fifth invention of the present invention is the first to fourth invention, wherein the grease is a fluorine grease and the solvent is a solvent-diluted aqueous lubricant composition that does not contain a fluorine-based solvent. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a solvent-diluted aqueous lubricant composition that can form a uniform grease film and provide good lubrication. [Modes for carrying out the invention]

[0018] The following describes in detail specific embodiments of the present invention (hereinafter referred to as "these embodiments"). It should be noted that the present invention is not limited to the following embodiments, and various modifications are possible without altering the essence of the invention.

[0019] ≪1. Composition of Solvent-Diluted Water-Based Lubricant Composition≫ The lubricant composition according to this embodiment is a solvent-diluted aqueous lubricant composition in which grease is dispersed in water, which is the solvent, using water as the solvent. When the solvent-diluted aqueous lubricant composition is applied to a part made of resin, metal, etc., the water, which is the solvent, is removed by evaporation upon drying, and a grease film is formed on the surface of the part to be coated.

[0020] The grease constituting the solvent-diluted aqueous lubricant composition contains a base oil and a thickener. The base oil constituting the grease is hydrophobic and contains one or more selected from perfluoropolyether oil and synthetic hydrocarbon oil. The grease is, for example, fluorine grease.

[0021] And the solvent-diluted aqueous lubricant composition according to the present embodiment is characterized by containing an additive containing a high molecular polysaccharide.

[0022] In the solvent-diluted aqueous lubricant composition, the state where the grease is "dispersed" in water as the solvent means that it also includes the state where the grease is dissolved in water. Also, in the solvent-diluted aqueous lubricant composition, water is used as the solvent with a high content ratio and does not contain a fluorine-based solvent.

[0023] (1) Grease The grease contains at least a base oil and a thickener. Also, in the solvent-diluted aqueous lubricant composition, the grease is dispersed in water as the solvent. The grease may contain components other than the base oil and the thickener.

[0024] (1-1) Base oil The base oil constitutes the grease and is a hydrophobic base oil selected from perfluoropolyether oil and synthetic hydrocarbon-based oil. The base oil may be a single type or a combination of two types. Particularly, from the perspective of PFAS regulations, it is more preferable to use synthetic hydrocarbon-based oil. Also, in addition to these hydrophobic base oils, other types of base oils may be included. For example, as other base oils, polyalkylene glycol synthetic lubricating oil can be mentioned.

[0025] (Perfluoropolyether oil) Fluorine oils are broadly classified into two types: those with a side-chain molecular structure and those with a linear molecular structure, and are selected based on factors such as lubrication mechanism, cost, and required lubricity. Perfluoropolyether oils are not particularly limited, but examples include those having structures represented by the following general formulas (i) to (iv).

[0026] F-(CFCF3-CF2-O-) n -CF2-CF3··(i) (Note that n in equation (i) is either 0 or a positive integer.) CF3-(O-CFCF3-CF2) p -(O-CF2-) q -O-CF3··(ii) (Note that in equation (ii), p and q are independently either 0 or a positive integer.) F-(CF2-CF2-CF2-O-) r -CF2-CF3··(iii) (Note that r in equation (iii) is 0 or a positive integer.) CF3-(O-CF2-CF2-) s -(O-CF2-) t -O-CF3··(iv) (Note that in equation (iv), s and t are independently either 0 or a positive integer.)

[0027] Specifically, commercially available products such as the Krytox series (manufactured by DuPont), FomblinY series (manufactured by Solvay Specialty Polymers Japan), FomblinM series (manufactured by Solvay Specialty Polymers Japan), FomblinW series (manufactured by Solvay Specialty Polymers Japan), FomblinZ series (manufactured by Solvay Specialty Polymers Japan), DemnamS series (manufactured by Daikin Industries), and PT series (manufactured by Nikka Chemical Co., Ltd.) can be used.

[0028] Furthermore, perfluoropolyether oils can be those having the structure described above, and among them, those with a kinematic viscosity of 15 mm at 40°C are particularly noteworthy. 2 / s~600mm 2 It is preferable to use one that is within the range of / s.

[0029] (Synthetic hydrocarbon oil) Examples of synthetic hydrocarbon oils include poly-α-olefins (α-olefins) produced by polymerizing α-olefins, either alone or in combination of two or more, using ethylene, propylene, butene, and their derivatives as raw materials. α-olefins with 6 to 14 carbon atoms are preferred.

[0030] Specific examples of synthetic hydrocarbon oils include poly-α-olefins (PAOs), which are oligomers of 1-decene and 1-dodecene; polybutenes, which are oligomers of 1-butene and isobutylene; and co-oligomers of ethylene or propylene with α-olefins. Alkylbenzenes and alkylnaphthalenes can also be used.

[0031] (Polyalkylene glycol synthetic lubricant) Polyalkylene glycol synthetic lubricants come in water-soluble and oil-soluble types. The water-soluble type is used in water-based hydraulic fluids, cutting fluids, and cleaning agents. Among these, polyethylene glycol has a wide range of molecular weights, with a number-average molecular weight of approximately 200 to 20,000.

[0032] (1-2) Thickener The thickener is not particularly limited, but examples include solid lubricants such as polytetrafluoroethylene, melamine cyanurate, and polyethylene solid powder. These can be used individually or in combination of two or more. Among these, melamine cyanurate or polyethylene solid powder is preferred from the viewpoint of PFAS regulations.

[0033] (Polytetrafluoroethylene) Polytetrafluoroethylene (PTFE) can be used in either unfired or fired form, depending on the lubrication properties and grease film characteristics. Polytetrafluoroethylene has a heat resistance temperature of 250°C to 260°C, exhibits low friction even under harsh lubrication conditions, and can extend the lifespan of machinery.

[0034] Unfired solid lubricants such as polytetrafluoroethylene have an amorphous shape, a large specific surface area and oil absorption capacity, and can produce grease viscosity even in small amounts, so they have been widely used as lubricants in the past. However, such solid lubricants are prone to deformation due to shear during lubrication, and can also deform due to mechanical shear when dispersed in a solvent, which can result in excessive viscosity for micro-components. On the other hand, fired solid lubricants such as polytetrafluoroethylene have a near-spherical particle shape, low oil absorption capacity, and are less prone to deformation even when shear is applied. Therefore, when dispersed in a solvent, the viscosity of the grease does not change easily even when mechanical shear occurs, effectively preventing parts from sticking together.

[0035] (Melamine cyanurate) Melamine cyanurate, possessing a graphite structure, exhibits lubricity comparable to polytetrafluoroethylene. Furthermore, melamine cyanurate has a heat resistance of 250°C to 300°C, generates an inert gas during combustion, dilutes oxygen concentration, and possesses flame retardant properties.

[0036] (polyethylene) Various solid polyethylene powders have been developed that possess properties similar to polytetrafluoroethylene, exhibiting effects such as improved slip resistance (friction), scratch resistance, and improved resistance to tapered abrasion and friction.

[0037] (2) Additives (High molecular weight polysaccharide) The solvent-diluted aqueous lubricant composition according to this embodiment is characterized by containing an additive containing a high-molecular-weight polysaccharide. By containing a high-molecular-weight polysaccharide, the hydrophobic base oil constituting the grease can be highly dispersed in the water solvent, resulting in a uniform composition. Furthermore, this enables the formation of a uniform grease film, providing excellent lubricity.

[0038] Furthermore, the statement that the hydrophobic base oil is "highly dispersed in water" due to the action of high molecular weight polysaccharides means that the hydrophobic base oil is atomized into fine particles in water and then dispersed in the water where it is fixed. In this way, high molecular weight polysaccharides make it possible to effectively disperse highly hydrophobic base oil in water, which is the solvent.

[0039] As the high-molecular-weight polysaccharide, one that forms a network structure through hydrogen bonding in water is used. The high-molecular-weight polysaccharide is stable through hydrogen bonding when no shear stress is applied, and becomes fluid when shear stress is applied. In the solvent-diluted aqueous lubricant composition, the high-molecular-weight polysaccharide forms a mesh-like network structure in the water solvent, and this network structure results in unique rheological properties such as extremely high pseudoplastic fluidity. Furthermore, this network structure also contributes to stabilizing oil droplets and fine particles of the base oil. In the solvent-diluted aqueous lubricant composition according to this embodiment, this action by the high-molecular-weight polysaccharide makes it possible to highly disperse the hydrophobic base oil constituting the grease in the water solvent.

[0040] As mentioned above, high molecular weight polysaccharides are not particularly limited as long as they form a network structure by hydrogen bonding in water. Specifically, examples include cellulosic polymers (methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, methylhydroxypropylcellulose, etc.), starch, starch derivatives, dextrin, alginic acids, agar, guar gum, locust bean gum, tara gum, fenugreek gum, tamarind gum, glucomannan, pectin, xanthan gum, gellan gum, κ-carrageenan, ι-carrageenan, λ-carrageenan, fercereran, cassia gum, curdlan, queen's seed, acacia gum, succinoglycan, glycosaminoglycan, etc. High molecular weight polysaccharides may be used individually or in combination of two or more.

[0041] Furthermore, as a high-molecular-weight polysaccharide, for example, Rheocrysta I-2SX manufactured by Daiichi Kogyo Seiyaku can be used. Rheocrysta I-2SX is an additive in which cellulose nanofibers (CNF) are dispersed in water and can be easily diluted.

[0042] The content of high molecular weight polysaccharides is not particularly limited, but is preferably in the range of 0.05% to 1.5% by mass, and more preferably in the range of 0.1% to 1.0% by mass, based on 100% by mass of the composition. In particular, by having a high molecular weight polysaccharide content in the range of 0.1% to 1.0% by mass, it is possible to disperse it highly in water, which is a solvent, regardless of the type of base oil, and to obtain a good solvent-dilutable water-based lubricant composition without impairing the applicability to the surface of the object to be coated, such as parts.

[0043] (Surfactants) In the solvent-diluted aqueous lubricant composition according to this embodiment, a surfactant may be included, although this is not an essential feature. By including a surfactant, the dispersibility of the solid powder constituting the grease can be further improved. In addition, the adhesion of the grease film to the substrate, particularly made of resin, can be improved, and the distribution of the grease film after application and drying can be made uniform.

[0044] The surfactant is not particularly limited and can be any surfactant that dissolves or disperses in water, regardless of the type of base oil and thickener that make up the grease. Furthermore, the surfactant may be a cationic surfactant, anionic surfactant, amphoteric surfactant, or nonionic surfactant, but the use of a nonionic surfactant is more preferable. More specifically, for example, polyglycerin fatty acid ester compounds and polyoxyethylene alkyl ethers can be used.

[0045] Furthermore, from the viewpoint of improving the dispersibility of solid components in water, surfactants with a high HLB value are preferred, for example, those with an HLB value of 13 or higher, and more preferably those with an HLB value of 14 or higher. Also, from the viewpoint of improving adhesion to resin when the object to be coated is a resin part, surfactants with a low HLB value are preferred, for example, those with an HLB value of 13 or less, and more preferably those with an HLB value of 11 or less. In this way, by using surfactants with different HLB values ​​depending on the purpose, it is possible to control the dispersibility in water (the solvent) and adhesion to resin, and to create a lubricant composition that exhibits superior lubricity.

[0046] (3)Water In the solvent-diluted aqueous lubricant composition according to this embodiment, water is a solvent that dilutes and disperses the grease components described above to form a solvent-diluted lubricant composition. When this solvent-diluted aqueous lubricant composition is applied to a part or the like to be coated, and the water solvent is evaporated by drying or other means, a grease film is formed on the coated surface.

[0047] In this embodiment, the solvent-diluted aqueous lubricant composition does not contain a fluorine-based solvent. As described above, by including a high-molecular-weight polysaccharide as an additive, even if the solvent is water, the hydrophobic base oil constituting the grease can be dispersed well.

[0048] The water used is not particularly limited and can be tap water, purified water, distilled water, or pure water. It may also contain an aqueous solvent such as a monohydric alcohol.

[0049] Furthermore, while the water content as a solvent is not particularly limited, it is preferably about 85% to 95% by mass, and more preferably about 90% to 94% by mass, based on 100% by mass of the composition.

[0050] (4) Other ingredients In addition to the components mentioned above, the solvent-diluted aqueous lubricant composition according to this embodiment may contain various other components as long as they do not hinder the effects of the solvent-diluted aqueous lubricant composition. For example, it may contain various components such as aqueous solvents (alcohols: ethanol, isopropanol, etc.), defoamers, metal corrosion inhibitors, and rust inhibitors.

[0051] ≪2. Condition of Solvent-Diluted Water-Based Lubricant Composition (Regarding Particle Size)≫ As described above, the solvent-diluted aqueous lubricant composition according to this embodiment is a mixture in which grease is dispersed in water, which is the solvent. In particular, by including an additive containing high molecular weight polysaccharides, the base oil constituting the grease can be dispersed well. Thus, the solvent-diluted aqueous lubricant composition is a mixture in which the base oil constituting the grease and a solid lubricant are dispersed in water, which is the solvent. Therefore, in order to apply it uniformly to the surface of a part or other object to be coated and form a uniform grease film, it is preferable that the particle size of the oil droplets and solid lubricant dispersed in the water be as fine as possible.

[0052] Specifically, in the solvent-diluted aqueous lubricant composition, the particle size of the oil droplets and solid lubricants dispersed in the water, which is the solvent, is preferably less than 50 μm in average particle size, and more preferably less than 30 μm. Thus, in the solvent-diluted aqueous lubricant composition according to this embodiment, the components of the oil droplets and solid lubricants, which consist of a hydrophobic base oil, are highly dispersed in the water, which is the solvent, at a size that is almost invisible to the naked eye.

[0053] The average particle size of oil droplets and solid lubricants dispersed in water can be measured, for example, using a known laser diffraction particle size distribution analyzer.

[0054] ≪3. Method for producing solvent-diluted aqueous lubricant compositions≫ The lubricant composition according to this embodiment can be manufactured by known methods. Specifically, for example, water as a solvent and a high-molecular-weight polysaccharide as an additive are weighed into a container, and a hydrophobic base oil is added and dispersed while stirring using a known stirring method. A dispersion of a thickener in water, a surfactant, and various other components as needed are also added and dispersed. This makes it possible to obtain a solvent-diluted aqueous lubricant composition in which grease is dispersed in water as a solvent.

[0055] For the dispersion of base oil in water or the dispersion of water in thickeners, wet stirring and dispersion treatment equipment such as propeller agitators, dissolvers, homomixers, dispermats, star mills, dyno mills, agitator mills, cleamixes, and film mixers can be used.

[0056] Furthermore, the process is not limited to adding each component in the order described above and mixing and stirring each component separately. Depending on the dispersion capacity of the stirring and dispersion equipment used, each component may be added and mixed and stirred simultaneously, or only some of the components may be mixed and stirred simultaneously. [Examples]

[0057] The present invention will be described in more detail below with reference to specific embodiments, but the present invention is not limited in any way to the following embodiments.

[0058] Manufacturing of solvent-dilutable aqueous lubricant compositions In Examples 1-7 and Comparative Examples 1-5, greases in the proportions shown in Table 1 below were dissolved in water as a solvent to produce solvent-dilutable aqueous lubricant compositions. In Table 1, the proportions are expressed in "mass%", and the following components were used to make up the compositions.

[0059] [component] (Base oil) Perfluoropolyether oil: PT-02 (manufactured by Nikka Chemical Co., Ltd.) Synthetic hydrocarbon oil: Spectrasyn4 (manufactured by ExxonMobil) (Thickener) Polytetrafluoroethylene:PTFE dispersion (60% product) (manufactured by Seishin Corporation) Melamine cyanurate: MC-6000 (manufactured by Nissan Chemical Corporation) Polyethylene: MaxWax70 (manufactured by Shamrock, USA) (Additives) Cellulose nanofibers: Rheocrysta I-2SX (contains 2% high molecular weight polysaccharides) (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) (Surfactants) Polyglycerin fatty acid ester (lauric acid ester) (HLB value 14.7): SY Glister ML-750 (manufactured by Sakamoto Pharmaceutical Co., Ltd.) Polyglycerin fatty acid ester (lauric acid ester) (HLB value 10.4): SY Glister ML-310 (manufactured by Sakamoto Pharmaceutical Co., Ltd.) (solvent) Water: Tap water

[0060] [Manufacturing Procedure] (Preparation of aqueous dispersion of thickener) First, for the thickeners, melamine cyanurate or polyethylene, aqueous dispersions were prepared with the ratio of the thickener to the surfactant [polyglycerin fatty acid ester (HLB value: 14.7)] as shown in Table 1 below, resulting in a solid component content of 9.2%. Specifically, water and the surfactant were added to a container and stirred, then the thickener was added and pre-dispersed using a dissolver. After that, a predetermined amount of zirconia beads were added to the container, it was sealed tightly, and shaken with a paint shaker to prepare an aqueous dispersion of the thickener. For the aqueous dispersion of polytetrafluoroethylene, a commercially available product was used.

[0061] (Preparation of solvent-diluted aqueous lubricant compositions) Water and high molecular weight polysaccharides, acting as solvents, were weighed into a container and highly dispersed using a dissolver. Base oil was then added and further dispersed. Next, a water dispersion of a thickener, a surfactant [polyglycerin fatty acid ester (HLB value: 10.4)], and water were added and stirred and mixed. This produced a solvent-diluted aqueous lubricant composition in which grease was dispersed in water.

[0062] In Reference Example 1, a conventional solvent-diluted fluorine-based lubricant composition was used, in which grease was dispersed in a fluorine-based solvent.

[0063] ≪Rating≫ The following evaluations were performed on the prepared solvent-diluted aqueous lubricant compositions.

[0064] [Dispersibility of base oil in solvents] The dispersibility of the base oil constituting the grease in water, the solvent, was evaluated. Specifically, in the examples, as shown in Table 1, water and high molecular weight polysaccharides were weighed into glass bottles, uniformly dispersed in a vortex mixer, and then the base oil was added and stirred in a vortex mixer to confirm the dispersibility. In the comparative examples, water and surfactants were weighed into glass bottles, uniformly dispersed or dissolved in a vortex mixer, and then the base oil was added and stirred in a vortex mixer to confirm the dispersibility. If the presence of the base oil could not be visually confirmed, it was evaluated as uniformly dispersed ("◎"), and if the presence of the base oil could be visually confirmed at the bottom of the glass bottle or on the surface of the liquid, it was evaluated as not uniformly dispersed ("×").

[0065] [PFAS substitutability] The composition of solvent-diluted aqueous lubricant compositions was evaluated to determine whether the solvent was replaced with a non-PFAS material. A rating of '◎' was given if water was used as the solvent and no fluorinated solvents were included, while a rating of '×' was given if fluorinated solvents were included.

[0066] [Evaluation of applicability] The applicability of solvent-diluted aqueous lubricant compositions to resins was evaluated. Specifically, a solvent-diluted aqueous lubricant composition was placed in a 50 mL glass beaker, and approximately half of a POM plate (40 × 50 × t2 mm) whose surface had been washed with ethanol was dipped into the beaker. After that, the plate was removed from the liquid surface and dried. A rating of '◎' was given for good applicability to the resin, '○' for good applicability with some repulsion, '△' for successful applicability with some repulsion, and '×' for no applicability.

[0067] [Evaluation of lubricity] The lubricity of a film formed with a solvent-diluted aqueous lubricant composition was evaluated. Specifically, the friction coefficient was measured using a friction player (manufactured by Resca) under the following test conditions. That is, a solvent-diluted aqueous lubricant composition was applied to a POM plate (40 × 50 × t2 mm) by dipping, dried, and then an ABS ball (3 / 8 inch) was placed in the upper jig, a 500 gf weight was placed on top, and the friction coefficient was measured after sliding for 30 minutes. (Measurement conditions for the coefficient of friction) Evaluation test machine: Friction player Test pieces: ABS ball (top), POM plate (bottom) Surface contact form: point contact Load: 500gf Sliding motion: sliding Sliding speed: 50 mm / s Sliding time: 30 minutes

[0068] Based on the measurement results, if the average friction coefficient over 30 minutes was less than 0.1, it was evaluated as having good lubricity (◎); if the friction coefficient was between 0.1 and 0.15, it was evaluated as having some lubricity and being usable under certain conditions (○); and if the friction coefficient was 0.2 or higher, it was evaluated as having poor lubricity (×).

[0069] ≪Results≫ Table 1 below shows the compositions of solvent-diluted aqueous lubricant compositions in the examples and comparative examples, along with a summary of the evaluation test results described above. For reference, the evaluation results for a conventional solvent-diluted fluorine-based lubricant composition are also shown.

[0070] [Table 1]

[0071] As shown in Table 1, the compositions of Examples 1 to 5, which contained high-molecular-weight polysaccharides as additives, showed that the hydrophobic base oil constituting the grease dispersed well in the water solvent, resulting in a uniform lubricant composition. As a result, the formed grease film was also uniform and exhibited good lubricity.

[0072] On the other hand, in Comparative Examples 1 to 5, which did not contain high molecular weight polysaccharides, the hydrophobic base oil did not disperse in the solvent water, and a uniform lubricant composition was not obtained. Furthermore, the results of Comparative Examples 2, 4, and 5 show that although various surfactants were added, the hydrophobic base oil could not be dispersed in the solvent water.

Claims

1. The solvent is water, A grease containing a base oil dispersed in water, which is the aforementioned solvent, and containing one or more selected from perfluoropolyether oil and synthetic hydrocarbon oil, and a thickener, Additives containing high molecular weight polysaccharides, A solvent-dilutable aqueous lubricant composition containing the following:

2. The aforementioned high-molecular-weight polysaccharides form a network structure in water through hydrogen bonding. The solvent-diluted aqueous lubricant composition according to claim 1.

3. The thickener comprises one or more selected from solid powders of polytetrafluoroethylene, melamine cyanurate, and polyethylene. The solvent-diluted aqueous lubricant composition according to claim 1 or 2.

4. Furthermore, it contains surfactants. The solvent-diluted aqueous lubricant composition according to claim 1 or 2.

5. The aforementioned grease is a fluorine grease. The solvent does not contain a fluorine-based solvent. The solvent-diluted aqueous lubricant composition according to claim 1 or 2.

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