Grease composition and method for producing grease composition

Abstract

To provide a grease composition hardly causing change in consistency with time, and to provide a method for producing the same.SOLUTION: The grease composition comprises a base oil, a calcium base material, a ≥ 12 c long-chain fatty acid, a ≤ 6 c short-chain fatty acid, and a metal-salt dispersant having a total base number of 20mgKOH / g or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a grease composition and a method for producing the grease composition. [Background technology]

[0002] In recent years, in view of the depletion of lithium resources and the rising cost of lithium, development of grease compositions using calcium as a base has been progressing. As a grease composition using a calcium base, for example, calcium complex grease, which uses a calcium soap consisting of calcium salts of dibasic acids and fatty acids as a thickener and has a dropping point of 270°C or higher, has been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-249419 Summary of the Invention [Problem to be solved by the invention]

[0004] However, grease compositions using calcium base materials tend to change in consistency over time, and improvement in this regard is desired. However, Patent Document 1 does not consider at all how to suppress the change in consistency of the grease composition.

[0005] Therefore, an object of the present invention is to provide a grease composition that is less likely to change in consistency over time, and a method for producing the same. [Means for solving the problem]

[0006] According to the present invention, the following [1] and [2] are provided. [1] A grease composition comprising a base oil, a calcium base material, a long-chain fatty acid having 12 or more carbon atoms, a short-chain fatty acid having 6 or less carbon atoms, and a metal salt dispersant having a total base number of 20 mg KOH / g or less. [2] A heating and stirring step (S1) and a cooling and stirring step (S2) are included, The method for producing a grease composition, wherein the heating and stirring step (S1) includes the following steps (S1-1) to (S1-3): Step (S1-1): A base oil, a long-chain fatty acid having 12 or more carbon atoms, a calcium base material, and a metal salt dispersant having a total base number of 20 mgKOH / g or less are heated and stirred. Step (S1-2): A short-chain fatty acid having 6 or less carbon atoms is blended with the heated and stirred product obtained in the step (S1-1). Step (S1-3): After the step (S1-2), the mixture is further heated and stirred. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a grease composition that is less likely to change in consistency over time, and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0008] The upper and lower limits of the ranges described herein can be combined in any way. For example, when the ranges are "A to B" and "C to D," the ranges "A to D" and "C to B" are also included in the scope of the present invention. Furthermore, unless otherwise specified, the numerical range "lower limit to upper limit" described in this specification means that the range is equal to or greater than the lower limit and equal to or less than the upper limit. In this specification, the numerical values ​​in the examples are numerical values ​​that can be used as upper or lower limit values.

[0009] [Embodiments of Grease Composition] The grease composition of this embodiment is composed of a base oil, a calcium base material, a long-chain fatty acid having 12 or more carbon atoms, a short-chain fatty acid having 6 or less carbon atoms, and a metal salt dispersant having a total base number of 20 mgKOH / g or less. In this embodiment, the grease composition defined as "comprised of a base oil, a calcium base material, a long-chain fatty acid having 12 or more carbon atoms, a short-chain fatty acid having 6 or less carbon atoms, and a metal salt dispersant having a total base number of 20 mgKOH / g or less" encompasses the following aspects. That is, one aspect of the grease composition of this embodiment contains a base oil, a calcium base material, a long-chain fatty acid having 12 or more carbon atoms, a short-chain fatty acid having 6 or less carbon atoms, and a metal salt dispersant having a total base number of 20 mgKOH / g or less, as well as a reaction product thereof. It may also contain modified products of these. The reaction product may be one or more selected from the group consisting of reaction product (A) produced from a calcium base material, a long-chain fatty acid having 12 or more carbon atoms, and a short-chain fatty acid having 6 or less carbon atoms; reaction product (B) produced from a metal salt dispersant having a total base number of 20 mg KOH / g or less, a long-chain fatty acid having 12 or more carbon atoms, and a short-chain fatty acid having 6 or less carbon atoms; and reaction product (C) produced from a calcium base material, a metal salt dispersant having a total base number of 20 mg KOH / g or less, a long-chain fatty acid having 12 or more carbon atoms, and a short-chain fatty acid having 6 or less carbon atoms. These reaction products (A) to (C) can function as thickeners in the grease composition of this embodiment. Note that, as a result of the production of reaction products (A) to (C), the calcium base material, the long-chain fatty acid having 12 or more carbon atoms, the short-chain fatty acid having 6 or less carbon atoms, and the metal salt dispersant having a total base number of 20 mg KOH / g or less may not be contained in the grease composition. Furthermore, as a result of the production of the reaction products (A) to (C), the calcium base material, the long-chain fatty acid having 12 or more carbon atoms, the short-chain fatty acid having 6 or less carbon atoms, and the metal salt dispersant having a total base number of 20 mgKOH / g or less may remain as modified substances in the grease composition.

[0010] The grease composition of the present embodiment may contain additives other than the above components within the scope of the present invention. In the grease composition of this embodiment, the total blend amount of the base oil, calcium base material, long-chain fatty acid having 12 or more carbon atoms, short-chain fatty acid having 6 or less carbon atoms, and metal salt dispersant having a total base number of 20 mgKOH / g or less is preferably 70 mass % or more, more preferably 80 mass % or more, and even more preferably 90 mass % or more, based on the total amount (100 mass %) of the grease composition.

[0011] Each component blended into the grease composition of this embodiment will be described in detail below. In addition, the blending amount of each component described below can be said to be a value reflecting the content of the component when the component does not form the above-mentioned reaction product or modified product. Therefore, for example, the blending amount of base oil is synonymous with the content of base oil.

[0012] <Base oil> The grease composition of the present embodiment is prepared by blending a base oil. The base oil may be any base oil commonly used in grease compositions, and may be, for example, one or more selected from mineral oils and synthetic oils. Of these, mineral oils are preferred from the viewpoints of manufacturing and improving lubricity through additive effects. The content of the mineral oil is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, even more preferably 70% by mass to 100% by mass, still more preferably 80% by mass to 100% by mass, and even more preferably 90% by mass to 100% by mass, based on the total amount of base oil (100% by mass).

[0013] Examples of mineral oils include distillates obtained by atmospheric or vacuum distillation of paraffinic crude oil, intermediate crude oil, or naphthenic crude oil, and refined oils obtained by refining these distillates. Refining methods for obtaining refined oils include, for example, hydroreforming, solvent extraction, solvent dewaxing, hydroisomerization dewaxing, hydrofinishing, and clay treatment. The mineral oils may be used alone or in combination of two or more.

[0014] Examples of synthetic oils include hydrocarbon oils, aromatic oils, ester oils, and ether oils, as well as synthetic oils obtained by isomerizing wax (GTL wax) produced by the Fischer-Tropsch process. Examples of hydrocarbon oils include normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, 1-decene and ethylene co-oligomer and other poly-α-olefins (PAO), and hydrogenated products thereof. Examples of aromatic oils include alkylbenzenes such as monoalkylbenzenes and dialkylbenzenes; alkylnaphthalenes such as monoalkylnaphthalenes, dialkylnaphthalenes, and polyalkylnaphthalenes; and the like. Examples of ester oils include diester oils such as dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl glutarate, and methyl acetyl ricinoleate; aromatic ester oils such as trioctyl trimellitate, tridecyl trimellitate, and tetraoctyl pyromellitate; polyol ester oils such as trimethylolpropane caprylate, trimethylolpropane bellargonate, pentaerythritol-2-ethylhexanoate, and pentaerythritol bellargonate; and complex ester oils such as oligoesters of polyhydric alcohols and mixed fatty acids of dibasic and monobasic acids. Examples of ether-based oils include polyglycols such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, and polypropylene glycol monoether; and phenyl ether-based oils such as monoalkyl triphenyl ether, alkyl diphenyl ether, dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, monoalkyl tetraphenyl ether, and dialkyl tetraphenyl ether. The synthetic oils may be used alone or in combination of two or more.

[0015] The base oil used in this embodiment may be a mixed base oil prepared by combining a high-viscosity base oil and a low-viscosity base oil to have a kinematic viscosity within the following range. Alternatively, a high viscosity base oil and a low viscosity base oil may be blended separately during the process of producing the grease composition, and the resulting grease composition may contain a mixed base oil. The kinematic viscosity at 40°C of the base oil used in this embodiment (hereinafter also referred to as "40°C kinematic viscosity") is preferably 30 to 500 mm 2 / s, more preferably 100 to 200 mm 2 / s, more preferably 130 to 170 mm 2 / s. In this specification, the kinematic viscosity at 40°C means a value measured in accordance with JIS K2283:2000. Here, the kinematic viscosity of the base oil at 40°C refers to the kinematic viscosity at 40°C of the base oil when it is made of one type of base oil, and in the case of a mixed base oil, refers to the kinematic viscosity at 40°C of the mixed base oil.

[0016] In the grease composition of this embodiment, the blending amount of the base oil is, based on the total amount (100 mass%) of the grease composition, preferably 50 mass% or more, more preferably 55 mass% or more, even more preferably 60 mass% or more, and is preferably 90 mass% or less, more preferably 85 mass% or less, even more preferably 80 mass% or less.

[0017] <Calcium base material> The grease composition of the present embodiment contains a calcium base material. The calcium base material may be any common material that can react with long-chain fatty acids and short-chain fatty acids to form a calcium complex soap that can function as a thickener. In this embodiment, the calcium base material is a material that does not contain an organic group and is clearly distinguished from the metal salt dispersant described below. Examples of calcium base materials include calcium hydroxide and quicklime, with calcium hydroxide being preferred. The calcium base material may be used alone or in combination of two or more.

[0018] In the grease composition of this embodiment, the amount of calcium base material blended is, based on the total amount (100% by mass) of the grease composition, preferably 0.1% by mass or more, more preferably 1.0% by mass or more, even more preferably 3.0% by mass or more, and is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, even more preferably 6.0% by mass or less.

[0019] <Long-chain fatty acids> The grease composition of the present embodiment contains a long-chain fatty acid. The long-chain fatty acid may be any fatty acid that can react with a calcium base material and a short-chain fatty acid to form a calcium complex soap that can function as a thickener. In this embodiment, the long-chain fatty acid has 12 or more carbon atoms, preferably 14 or more, more preferably 16 or more, even more preferably 18 or more, and even more preferably 20 or more. When the carbon number of the long-chain fatty acid is within the above range, the effects of the present invention are more easily improved, and the consistency of the grease composition can be more easily adjusted to an appropriate range. It can also be easier to improve the dropping point. The upper limit of the carbon number of the long-chain fatty acid is preferably 24 or less, from the viewpoint of availability of long-chain fatty acids. Examples of such long-chain fatty acids include one or more selected from monobasic acids and dibasic acids having a carbon number within the above range and having an alkyl or alkenyl group. Among these, from the viewpoint of improving the effects of the present invention, monobasic acids having a carbon number within the above range and having an alkyl or alkenyl group are preferred. Examples of such monobasic acids include dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, icosanoic acid, henicosanoic acid, docosanoic acid (behenic acid), tricosanoic acid, tetracosanoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid, heptadecenoic acid, octadecenoic acid, nonadecenoic acid, icosenoic acid, henicosanoic acid, docosanoic acid, tricosenoic acid, and tetracosenoic acid, etc. Among these, icosanoic acid, henicosanoic acid, docosanoic acid (behenic acid), tricosanoic acid, and tetracosanoic acid are preferred, and docosanoic acid (behenic acid) is more preferred. The long-chain fatty acids may be used alone or in combination of two or more.

[0020] In the grease composition of this embodiment, the blending amount of the long-chain fatty acid is, based on the total amount (100% by mass) of the grease composition, preferably 5.0% by mass or more, more preferably 8.0% by mass or more, even more preferably 13.0% by mass or more, and is preferably 30.0% by mass or less, more preferably 25.0% by mass or less, even more preferably 20.0% by mass or less.

[0021] <Short-chain fatty acids> The grease composition of the present embodiment contains a short-chain fatty acid. The short-chain fatty acid may be any fatty acid that can react with a calcium base material and a long-chain fatty acid to form a calcium complex soap that can function as a thickener. In this embodiment, the short-chain fatty acid has 6 or less carbon atoms, preferably 4 or less, more preferably 3 or less, and even more preferably 2. When the carbon number of the short-chain fatty acid is within the above range, the effects of the present invention are more likely to be improved. In addition, unreacted short-chain fatty acid is more likely to volatilize, making it less likely that the raw material will remain in the grease composition. In addition, this also contributes to improving the mechanical stability and consistency yield of the grease composition. Examples of such short-chain fatty acids include one or more selected from monobasic acids and dibasic acids having a carbon number within the above range and having an alkyl or alkenyl group. Among these, from the viewpoint of improving the effects of the present invention, monobasic acids having a carbon number within the above range and having an alkyl or alkenyl group are preferred. Examples of such monobasic acids include acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, acrylic acid, methacrylic acid, butenoic acid, pentenoic acid, and hexenoic acid. Among these, acetic acid, propionic acid, and butanoic acid are preferred, and acetic acid and propionic acid are more preferred. In particular, acetic acid is preferred from the viewpoint that it is a low-viscosity liquid, so that unreacted substances are easily volatilized and raw materials are less likely to remain in the grease composition, and further from the viewpoint of improving the mechanical stability and consistency yield of the grease composition. The long-chain fatty acids may be used alone or in combination of two or more.

[0022] In the grease composition of this embodiment, the blending amount of the short-chain fatty acid is, based on the total amount (100 mass%) of the grease composition, preferably 0.5 mass% or more, more preferably 1.0 mass% or more, even more preferably 2.0 mass% or more, and is preferably 5.0 mass% or less, more preferably 4.0 mass% or less, even more preferably 3.0 mass% or less.

[0023] <Metal salt dispersant> The grease composition of this embodiment contains a metal salt dispersant having a total base number of 20 mgKOH / g or less. By blending a metal salt dispersant with a total base number of 20 mgKOH / g or less into the grease composition, it is thought that the thickener, which is uniformly dispersed in the oil immediately after production, is prevented from aggregating over time, thereby maintaining uniform dispersion of the thickener and thereby preventing changes in the consistency of the grease composition over time. Examples of metal salts that can function as dispersants include organic acid metal salt compounds containing a metal atom selected from alkali metals and alkaline earth metals, and specific examples include metal salicylates, metal phenates, and metal sulfonates, each containing a metal atom selected from alkali metals and alkaline earth metals. Among these, metal sulfonates are preferred from the viewpoint of improving the effects of the present invention. In this embodiment, the term "alkali metal" refers to sodium and potassium, and the term "alkaline earth metal" refers to magnesium, calcium, strontium, and barium. As the metal atom contained in the metal salt capable of functioning as a dispersant, sodium, calcium, magnesium, or barium is preferred, from the viewpoint of improving the effects of the present invention, and calcium is more preferred. Furthermore, the metal salt that can function as a dispersant is preferably calcium sulfonate, from the viewpoint of making it easier to improve the effects of the present invention. The dispersant may be used alone or in combination of two or more kinds.

[0024] In this embodiment, the calcium sulfonate is preferably a compound represented by the following general formula (1), from the viewpoint of further improving the effects of the present invention.

[0025] [ka]

[0026] In the general formula (1), each Ar is independently an aromatic ring having 6 to 10 carbon atoms. Each R is independently a hydrocarbon group having 1 to 20 carbon atoms. Each n is independently an integer of 0 to 5.

[0027] In the above general formula (1), Ar is preferably a benzene ring or a naphthalene ring, more preferably a naphthalene ring. In the general formula (1), R is preferably a linear or branched alkyl group, more preferably a linear alkyl group. The number of carbon atoms in the alkyl group that can be selected as R is preferably 6 to 18, more preferably 7 to 14, and even more preferably 8 to 10. In the above general formula (1), n ​​is preferably 1 to 3, and more preferably 2. In this embodiment, a particularly preferred compound as the calcium sulfonate is, for example, dinonylnaphthalenesulfonic acid calcium salt.

[0028] In this embodiment, the total base number of the metal salt dispersant is 20 mgKOH / g or less. By setting the total base number of the metal salt dispersant to 20 mgKOH / g or less, it is possible to easily suppress changes in the consistency of the grease composition over time. From the viewpoint of making it easier to suppress changes in consistency of the grease composition over time, the total base number of the metal salt dispersant (preferably calcium sulfonate) is preferably 10 mgKOH / g or less, more preferably 5.0 mgKOH / g or less, even more preferably 1.0 mgKOH / g or less, and still more preferably 0.5 mgKOH / g or less. In this specification, the total base number of the metal salt dispersant is a value measured by the perchloric acid method in accordance with JIS K2501-9:2003.

[0029] In the grease composition of this embodiment, the blending amount of the metal salt dispersant having a total base number of 20 mgKOH / g or less is, based on the total amount (100 mass%) of the grease composition, preferably 0.05 mass% or more, more preferably 0.15 mass% or more, even more preferably 0.25 mass% or more, and is preferably 2.5 mass% or less, more preferably 1.5 mass% or less, even more preferably 1.0 mass% or less.

[0030] <Mixing ratio of calcium base material and metal salt dispersant> In the grease composition of the present embodiment, the blending ratio of the calcium base material to the metal salt dispersant [calcium base material / metal salt dispersant] is preferably 1.6 to 16.0 by mass, more preferably 2.0 to 14.0, and even more preferably 4.0 to 12.0, from the viewpoint of improving the effects of the present invention.

[0031] <Other additives (X)> The grease composition of this embodiment may further contain a polyhydric alcohol. The grease composition of this embodiment may further contain an antifoaming agent. That is, the grease composition of this embodiment may further contain one or more additives selected from the group consisting of polyhydric alcohols and antifoaming agents (hereinafter also referred to as "other additives (X)").

[0032] (Polyhydric alcohol) The grease composition of the present embodiment preferably contains a polyhydric alcohol. By blending a polyhydric alcohol, it becomes easier to adjust the consistency of the grease composition to an appropriate value. The polyhydric alcohol is preferably a dihydric or trihydric alcohol having 2 to 5 carbon atoms. Specific examples include 1,1-ethanediol, 1,2-ethanediol (ethylene glycol), 1,1-butanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-heptanediol, and 1,2,3-propanetriol (glycerin). Among these, 1,2,3-propanetriol (glycerin) is preferred. The amount of polyhydric alcohol blended is adjusted appropriately depending on the consistency required for the grease composition, and is preferably 0.5 to 2.0 mass%, more preferably 0.7 to 1.7 mass%, and even more preferably 0.8 to 1.5 mass%.

[0033] (Antifoaming agent) The grease composition of the present embodiment preferably contains an antifoaming agent. By adding an antifoaming agent, it becomes easier to adjust the consistency of the grease composition to an appropriate value. The antifoaming agent may be a silicone-based antifoaming agent such as dimethylpolysiloxane. The blending amount of the antifoaming agent (active ingredient) is preferably 0.001% by mass to 0.005% by mass, more preferably 0.0005% by mass to 0.005% by mass, and even more preferably 0.0001% by mass to 0.005% by mass.

[0034] <Other additives (Y)> The grease composition of the present embodiment may further contain one or more additives selected from the group consisting of rust inhibitors, metal deactivators, antioxidants, anti-wear agents, and extreme pressure agents (hereinafter also referred to as "other additives (Y)"). The total amount of the other additives (Y) added is preferably 1.0 mass % to 20.0 mass %, more preferably 2.0 mass % to 15.0 mass %, and even more preferably 3.0 mass % to 10.0 mass %, based on the total amount (100 mass %) of the grease composition.

[0035] <Properties of grease composition> The grease composition of the present embodiment preferably satisfies the following physical properties.

[0036] (Consistency) The grease composition of this embodiment preferably has a worked penetration at 25°C of 175 to 430, more preferably 220 to 385, even more preferably 220 to 295, and even more preferably 220 to 250.

[0037] Furthermore, the grease composition of this embodiment preferably exhibits a change in worked penetration at 25°C of less than 8% after being left to stand in an environment at 25°C for 720 hours immediately after production. Therefore, it can be said that the grease composition of this embodiment is excellent in suppressing changes in consistency of the grease composition, particularly during storage and distribution.

[0038] In this specification, the worked penetration of a grease composition at 25°C means a value measured at 25°C in accordance with JIS K2220:2013 (Clause 7).

[0039] (dropping point) The grease composition of this embodiment preferably has a dropping point of 230°C or higher. In this specification, the dropping point of a grease composition means a value measured in accordance with JIS K2220:2013 (Clause 8).

[0040] [Method for producing grease composition] The method for producing the grease composition of this embodiment includes a heating and stirring step (S1) and a cooling and stirring step (S2). The heating and stirring step (S1) includes the following steps (S1-1) to (S1-3): Step (S1-1): A base oil, a long-chain fatty acid having 12 or more carbon atoms, a calcium base material, and a metal salt dispersant having a total base number of 20 mgKOH / g or less are heated and stirred. Step (S1-2): A short-chain fatty acid having 6 or less carbon atoms is added to the heated and stirred product obtained in step (S1-1). Step (S1-3): After step (S1-2), heating and stirring are further carried out.

[0041] In step (S1-1), a base oil, a long-chain fatty acid having 12 or more carbon atoms, a calcium base material, and a metal salt dispersant having a total base number of 20 mgKOH / g or less are heated and stirred. Then, a short-chain fatty acid having 6 or less carbon atoms is blended with the heated and stirred mixture obtained in step (S1-1), and step (S1-2) is carried out to allow the saponification reaction to proceed. Furthermore, from the viewpoint of easily improving the effects of the present invention, the timing for carrying out step (S1-2) is preferably when the temperature of the heated and stirred product obtained in step (S1-1) reaches a range of 60°C to 80°C. In the step (S1-1), other additives (X) may be added as needed. Among the other additives (X), by blending a polyhydric alcohol such as glycerin at this timing, it becomes easier to adjust the consistency of the grease composition to an appropriate value.

[0042] In step (S1-3), heating and stirring is further carried out after step (S1-2). From the viewpoint of easily improving the effects of the present invention, the heating and stirring in step (S1-3) is preferably carried out until the temperature of the heated and stirred product reaches 180°C to 210°C. Furthermore, from the viewpoint of facilitating the improvement of the effects of the present invention, it is preferable that after the temperature of the heated and stirred product reaches 180°C to 210°C, that temperature is maintained for a certain period of time (preferably 1 minute to 10 minutes).

[0043] In the cooling and stirring step (S2), the heated and stirred product obtained in step (S1-3) is cooled and stirred. The cooling method is not particularly limited, but a method in which a base oil is added to the heated and stirred product and then stirred, or cooling using a cooling device in the reaction vessel is preferred.

[0044] After the cooling and stirring step (S2) is completed, the mixture is further subjected to a roll mill treatment or the like to produce a grease composition. In this case, if necessary, other additives (Y) may be blended using a mixer or the like after the roll mill treatment.

[0045] [Uses of grease composition] Examples of mechanical parts to which the grease composition of the present embodiment can be applied include bearings and gears, and more specifically, examples include various bearings such as sliding bearings and rolling bearings, gears, internal combustion engines, brakes, torque transmission device parts, fluid couplings, compression device parts, chains, hydraulic device parts, vacuum pump device parts, watch parts, hard disk drive parts, refrigeration machine parts, cutting machine parts, rolling mill parts, drawing and drawing machine parts, rolling machine parts, forging machine parts, heat treatment device parts, heat exchanger parts, washing machine parts, shock absorber parts, sealing device parts, and the like. The grease composition of this embodiment is also suitable for use in lubricating sliding parts of general bearings, bearings for construction machinery, and the like.

[0046] [One aspect of the present invention provided] According to one aspect of the present invention, the following [1] to

[12] are provided. [1] A grease composition comprising a base oil, a calcium base material, a long-chain fatty acid having 12 or more carbon atoms, a short-chain fatty acid having 6 or less carbon atoms, and a metal salt dispersant having a total base number of 20 mg KOH / g or less. [2] The grease composition according to the above [1], which has a worked penetration at 25°C of 175 to 430. [3] The grease composition according to [1] or [2] above, which has a dropping point of 230°C or higher. [4] The grease composition according to any one of the above [1] to [3], wherein the long-chain fatty acid has 20 or more carbon atoms. [5] The grease composition according to any one of the above [1] to [4], wherein the long-chain fatty acid is behenic acid. [6] The grease composition according to any one of the above [1] to [5], wherein the short-chain fatty acid is acetic acid. [7] The grease composition according to any one of the above [1] to [6], wherein the calcium base material is calcium hydroxide. [8] The grease composition according to any one of the above [1] to [7], wherein the metal salt dispersant is calcium sulfonate. [9] The grease composition according to any one of the above [1] to [8], further comprising a polyhydric alcohol.

[10] The grease composition according to any one of the above [1] to [9], further comprising an antifoaming agent.

[11] The grease composition according to any one of the above [1] to

[10] , further comprising one or more additives selected from the group consisting of rust inhibitors, metal deactivators, antioxidants, anti-wear agents, and extreme pressure agents.

[12] A heating and stirring step (S1) and a cooling and stirring step (S2), The method for producing a grease composition, wherein the heating and stirring step (S1) includes the following steps (S1-1) to (S1-3): Step (S1-1): A base oil, a long-chain fatty acid having 12 or more carbon atoms, a calcium base material, and a metal salt dispersant having a total base number of 20 mgKOH / g or less are heated and stirred. Step (S1-2): A short-chain fatty acid having 6 or less carbon atoms is blended with the heated and stirred product obtained in the step (S1-1). Step (S1-3): After the step (S1-2), the mixture is further heated and stirred. [Example]

[0047] The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0048] [Methods for measuring various physical properties] Various physical properties of the raw materials used in the examples were measured by the following methods. (1) Kinematic viscosity of base oil at 40°C Measurements were made in accordance with JIS K2283:2000. (2) Total base number of metal salt dispersant Measurement was carried out by the perchloric acid method in accordance with JIS K2501-9:2003.

[0049] [Example A1 and Comparative Examples A'1 to A'4] Grease compositions were produced by the methods described in Example A1 and Comparative Examples A'1 to A'4, and the evaluations described below were carried out.

[0050] <Raw materials> Details of the raw materials used in Example A1 and Comparative Examples A'1 to A'4 are shown below. The blending ratio of each raw material (unit: mass %) was as shown in Table 1 below.

[0051] (1) Base oil Hydrogenated medium viscosity paraffin (mineral oil, kinematic viscosity at 40°C: 90.51 mm) 2 / s) Hydrogenated high viscosity oil (mineral oil, kinematic viscosity at 40°C: 408.8 mm 2 / s) (2) Long-chain fatty acids with 12 or more carbon atoms Behenic acid Behenic acid is a saturated fatty acid with 22 carbon atoms and is a monobasic acid. (3) Short-chain fatty acids with six or fewer carbon atoms acetic acid Acetic acid is a saturated fatty acid with two carbon atoms and is a monobasic acid. (4) Calcium substrate Calcium hydroxide (Ca(OH)2) (5) Dispersant Metal salt dispersant 1: Neutral dinonylnaphthalenesulfonic acid calcium salt (total base number: 0.35 mg KOH / g) diluted with diluent oil to an active ingredient content of approximately 50% by mass Metal salt dispersant 2: Basic dinonylnaphthalenesulfonic acid calcium salt (total base number: 25 mg KOH / g) diluted with diluent oil to an active ingredient content of approximately 50% by mass Ashless dispersant 1: Alkyl succinimide Ashless dispersant 2: Polyamide (6) Polyhydric alcohol Glycerin (1,2,3-propanetriol) (7) Antifoaming agent Dimethylpolysiloxane diluted with hydrogenated light oil Dimethylpolysiloxane content: Approximately 1% by mass (based on the total amount of antifoaming agent)

[0052] <Comparative example A'1> Hydrogenated medium-viscosity paraffin (476.50 g), behenic acid (165.20 g), calcium hydroxide (39.10 g), glycerin (10.00 g), and an antifoaming agent (1.00 g) were charged into a reaction vessel, and the mixture was heated while stirring at a stirring speed of 130 rpm. When the temperature of the contents in the vessel reached 74°C, heating was stopped. After heating was stopped, the stirring speed was increased to 200 rpm and acetic acid (27.50 g) was added. Next, heating was started again while maintaining the stirring speed at 200 rpm, and when the temperature of the contents in the kettle reached 200°C, that temperature was maintained for 5 minutes. Then, hydrogenated high-viscosity oil (280.70 g) was added as cooling oil, and the contents in the kettle were cooled while stirring at a stirring speed of 200 rpm until the temperature reached 70°C. Finally, a roll mill was used to carry out two passes of dispersion treatment. Grease composition A'1 was prepared according to the above procedure.

[0053] Example A1 Grease composition A1 was prepared in the same manner as in Comparative Example A'1, except that when hydrogenated medium-viscosity paraffin (470.03 g), behenic acid (165.20 g), calcium hydroxide (39.10 g), glycerin (10.00 g), and antifoaming agent (1.00 g) were charged into a reaction vessel, metal salt dispersant 1 (10.00 g) was also charged as a dispersant.

[0054] <Comparative example A'2> Grease composition A'2 was prepared in the same manner as comparative example A'1, except that when hydrogenated medium-viscosity paraffin (470.03 g), behenic acid (165.20 g), calcium hydroxide (39.10 g), glycerin (10.00 g), and antifoaming agent (1.00 g) were charged into a reaction vessel, metal salt dispersant 2 (10.00 g) was also charged as a dispersant.

[0055] <Comparative example A'3> Grease composition A'3 was prepared in the same manner as comparative example A'1, except that ashless dispersant 1 (10.00 g) was also added as a dispersant when hydrogenated medium-viscosity paraffin (470.03 g), behenic acid (165.20 g), calcium hydroxide (39.10 g), glycerin (10.00 g), and antifoaming agent (1.00 g) were added to a reaction vessel.

[0056] <Comparative example A'4> Grease composition A'4 was prepared in the same manner as comparative example A'1, except that ashless dispersant 2 (10.00 g) was also added as a dispersant when hydrogenated medium-viscosity paraffin (470.03 g), behenic acid (165.20 g), calcium hydroxide (39.10 g), glycerin (10.00 g), and antifoaming agent (1.00 g) were added to a reaction vessel.

[0057] <Rating 1> The worked penetration of the grease composition at 25°C was measured immediately after production. The produced grease compositions were allowed to stand in an environment at 25°C for 24 hours, 48 ​​hours, 96 hours, and 720 hours, and then the worked penetration of the grease compositions at 25°C was measured. The worked penetration of the grease composition was measured at 25°C in accordance with JIS K2220:2013 (Clause 7). The results are shown in Table 1. In Table 1, the amounts of metal salt dispersants 1 and 2 and antifoaming agent included dilution oil.

[0058] [Table 1]

[0059] From Table 1, we can see the following: It can be seen that the grease compositions of Comparative Examples A'1, A'3, and A'4 all showed large changes in consistency over time. Furthermore, it can be seen that the grease composition of Comparative Example A'2 shows little change in consistency over time up to 96 hours, but after 720 hours the grease composition hardens and the consistency decreases. In contrast, the grease composition of Example A1 showed little change in consistency even after 720 hours, indicating that the consistency is unlikely to change over time.

[0060] [Example B1 and Comparative Example B'1] Grease compositions were prepared by the methods described in Example B1 and Comparative Example B'1, and the evaluations described below were carried out.

[0061] <Raw materials> In Example B1 and Comparative Example B'1, the following raw materials were used in addition to the raw materials used in Example A1 and Comparative Example A'2. The blending ratio of each raw material (unit: mass %) was as shown in Table 2. (8) Rust inhibitor Rust inhibitor 1: A mixture of calcium sulfonate, sodium sulfonate, mineral oil, glycol derivative, and water Rust inhibitor 2: Mixture of alkyldithiothiadiazole and (5-(tert-nonyldisulfanyl)-1,3,4-thiadiazole-2(3H)-thione) (9) Metal deactivator Stearyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (10) Antioxidants Mixture of bis(nonylphenyl)amine and diphenylamine (11) Anti-wear agent Zinc bis(N,N-diamyldithiocarbamate) diluted with hydrogenated naphthenic oil (12) Extreme pressure agents Mixture of tris(isopropylphenyl)phosphate, triphenylphosphate, and phenol

[0062] Example B1 When producing grease composition A1 in Example A1, after the final roll mill step, a rust inhibitor, a metal deactivator, an antioxidant, an anti-wear agent, and an extreme pressure agent were blended using a mixer to prepare grease composition B1.

[0063] <Comparative example B'1> When producing grease composition A'2 in Comparative Example A'2, after the final roll mill process, a mixer was used to blend a rust inhibitor, a metal deactivator, an antioxidant, an anti-wear agent, and an extreme pressure agent to prepare grease composition B'1.

[0064] <Rating 2> The same evaluation as in Evaluation 1 above was carried out immediately after the production of the grease composition and after 720 hours. Additionally, the dropping point of the grease composition B1 was measured in accordance with JIS K2220:2013 (Clause 8). The results are shown in Table 2. In Table 2, the amounts of metal salt dispersants 1 and 2, antifoaming agent, rust inhibitors 1 and 2, and anti-wear agent are amounts including dilution oil.

[0065] [Table 2]

[0066] From Table 2, we can see the following: It can be seen that the grease compositions of Comparative Example B'1 all showed large changes in consistency over time. In contrast, the grease composition of Example B1 showed little change in consistency even after 720 hours, indicating that the consistency is unlikely to change over time.

Claims

1. A grease composition comprising a base oil, a calcium base material, a long-chain fatty acid having 12 or more carbon atoms, a short-chain fatty acid having 6 or less carbon atoms, and a metal salt dispersant having a total base number of 20 mgKOH / g or less.

2. 2. The grease composition according to claim 1, which has a worked penetration at 25°C of 175 to 430.

3. 3. The grease composition according to claim 1, wherein the dropping point is 230°C or higher.

4. The grease composition according to any one of claims 1 to 3, wherein the long-chain fatty acid has 20 or more carbon atoms.

5. The grease composition according to any one of claims 1 to 4, wherein the long-chain fatty acid is behenic acid.

6. The grease composition according to any one of claims 1 to 5, wherein the short-chain fatty acid is acetic acid.

7. The grease composition according to any one of claims 1 to 6, wherein the calcium base material is calcium hydroxide.

8. The grease composition according to any one of claims 1 to 7, wherein the metal salt dispersant is calcium sulfonate.

9. The grease composition according to any one of claims 1 to 8, further comprising a polyhydric alcohol.

10. The grease composition according to any one of claims 1 to 9, further comprising an antifoaming agent.

11. The grease composition according to any one of claims 1 to 10, further comprising one or more additives selected from the group consisting of rust inhibitors, metal deactivators, antioxidants, antiwear agents, and extreme pressure agents.

12. The method includes a heating and stirring step (S1) and a cooling and stirring step (S2), The method for producing a grease composition, wherein the heating and stirring step (S1) includes the following steps (S1-1) to (S1-3): Step (S1-1): A base oil, a long-chain fatty acid having 12 or more carbon atoms, a calcium base material, and a metal salt dispersant having a total base number of 20 mgKOH / g or less are heated and stirred. Step (S1-2): A short-chain fatty acid having 6 or less carbon atoms is blended with the heated and stirred product obtained in the step (S1-1). Step (S1-3): After the step (S1-2), the mixture is further heated and stirred.

Images