US20220145207A1 - Grease composition - Google Patents

Grease composition Download PDF

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Publication number
US20220145207A1
US20220145207A1 US17/437,155 US202017437155A US2022145207A1 US 20220145207 A1 US20220145207 A1 US 20220145207A1 US 202017437155 A US202017437155 A US 202017437155A US 2022145207 A1 US2022145207 A1 US 2022145207A1
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Prior art keywords
nanofibers
grease composition
mass
base oil
oil
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US17/437,155
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English (en)
Inventor
Yusuke Nakanishi
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Idemitsu Kosan Co Ltd
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Idemitsu Kosan Co Ltd
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Assigned to IDEMITSU KOSAN CO.,LTD. reassignment IDEMITSU KOSAN CO.,LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NAKANISHI, YUSUKE
Publication of US20220145207A1 publication Critical patent/US20220145207A1/en
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated
    • C10M171/06—Particles of special shape or size
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M119/00—Lubricating compositions characterised by the thickener being a macromolecular compound
    • C10M119/04—Lubricating compositions characterised by the thickener being a macromolecular compound containing oxygen
    • C10M119/20—Polysaccharides, e.g. cellulose
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M123/00—Lubricating compositions characterised by the thickener being a mixture of two or more compounds covered by more than one of the main groups C10M113/00 - C10M121/00, each of these compounds being essential
    • C10M123/04—Lubricating compositions characterised by the thickener being a mixture of two or more compounds covered by more than one of the main groups C10M113/00 - C10M121/00, each of these compounds being essential at least one of them being a macromolecular compound
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M125/00—Lubricating compositions characterised by the additive being an inorganic material
    • C10M125/26—Compounds containing silicon or boron, e.g. silica, sand
    • C10M125/30—Clay
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M145/00—Lubricating compositions characterised by the additive being a macromolecular compound containing oxygen
    • C10M145/40—Polysaccharides, e.g. cellulose
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
    • C10M169/06—Mixtures of thickeners and additives
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
    • C10M2201/10—Compounds containing silicon
    • C10M2201/102—Silicates
    • C10M2201/103—Clays; Mica; Zeolites
    • C10M2201/1036—Clays; Mica; Zeolites used as thickening agents
    • C—CHEMISTRY; METALLURGY
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    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
    • C10M2201/14—Inorganic compounds or elements as ingredients in lubricant compositions inorganic compounds surface treated with organic compounds
    • C—CHEMISTRY; METALLURGY
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    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
    • C10M2203/003—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions used as base material
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
    • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
    • C10M2205/028—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers containing aliphatic monomers having more than four carbon atoms
    • C10M2205/0285—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers containing aliphatic monomers having more than four carbon atoms used as base material
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
    • C10M2205/06—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing conjugated dienes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/10—Carboxylix acids; Neutral salts thereof
    • C10M2207/12—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms
    • C10M2207/125—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids
    • C10M2207/126—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids monocarboxylic
    • C10M2207/1265—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids monocarboxylic used as thickening agent
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/28—Esters
    • C10M2207/287—Partial esters
    • C10M2207/289—Partial esters containing free hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
    • C10M2209/12—Polysaccharides, e.g. cellulose, biopolymers
    • C10M2209/126—Polysaccharides, e.g. cellulose, biopolymers used as thickening agents
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2215/00—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant Compositions
    • C10M2215/02—Amines, e.g. polyalkylene polyamines; Quaternary amines
    • C10M2215/06—Amines, e.g. polyalkylene polyamines; Quaternary amines having amino groups bound to carbon atoms of six-membered aromatic rings
    • C10M2215/064—Di- and triaryl amines
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2223/00—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
    • C10M2223/02—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
    • C10M2223/04—Phosphate esters
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2223/00—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
    • C10M2223/02—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
    • C10M2223/04—Phosphate esters
    • C10M2223/047—Thioderivatives not containing metallic elements
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/02—Viscosity; Viscosity index
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/055—Particles related characteristics
    • C10N2020/063—Fibrous forms
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/54—Fuel economy
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/62—Food grade properties
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/68—Shear stability
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/04—Oil-bath; Gear-boxes; Automatic transmissions; Traction drives
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2050/00—Form in which the lubricant is applied to the material being lubricated
    • C10N2050/10—Form in which the lubricant is applied to the material being lubricated semi-solid; greasy

Definitions

  • the present invention relates to a grease composition. More specifically, the present invention relates to a grease composition used in a speed reducer and a speed increaser.
  • Grease is easier to seal than lubricating oil, and can reduce the size and weight of the machine to which it is applied. Therefore, it has been widely used for lubrication of various sliding parts of automobiles, electric appliances, industrial machinery, industrial machines and the like.
  • the speed reducer has a mechanism that applies torque to the input side to reduce the speed and transmit the torque to the output side.
  • the speed increaser has a mechanism that applies torque to the input side to increase the speed and transmit the torque to the output side.
  • Grease used in lubricating portions of a speed reducer and a speed increaser is required to have excellent energy transfer efficiency from the viewpoint of suppressing loss of torque (energy) applied to the input side and transmitting the torque to the output side without waste.
  • the object of the present invention is to provide a grease composition for a speed reducer and a speed increaser, which is excellent in both leakage prevention performance and energy transfer efficiency.
  • the present inventors have found that a grease composition containing a base oil and a specific nanofiber can solve the aforementioned problems, and have completed the present invention.
  • the present invention is concerned with the following [1] to [10].
  • a grease composition used for a speed reducer and a speed increaser containing: a base oil (A); and nanofibers (B) having a thickness (d) of 1 to 500 nm, wherein the nanofibers (B) are one or more selected from cellulose nanofibers (B1) and modified cellulose nanofibers (B2).
  • the base oil (A) is a mixed base oil containing a low-viscosity base oil (A1) having a kinematic viscosity at 40° C. of 5 to 150 mm 2 /s and a high-viscosity base oil (A2) having a kinematic viscosity at 40° C. of 200 to 1000 mm 2 /s.
  • A1 low-viscosity base oil
  • A2 high-viscosity base oil
  • a lubrication method including lubricating a lubricating portion of a speed reducer or a speed increaser with the grease composition as set forth in any of [1] to [7].
  • a lubrication method including lubricating a lubricating portion of a food machine including a speed reducer or a speed increaser with the grease composition as set forth in any of [1] to [7].
  • FIG. 1 is a schematic view of an apparatus used for measuring torque transmission efficiency as an index of energy transfer efficiency in this embodiment.
  • the lower limit value and the upper limit value described in stages can be independently combined with each other.
  • a preferable numerical range for example, a range of content or the like
  • the lower limit value and the upper limit value described in stages can be independently combined with each other.
  • preferably 10 to 90, and more preferably 30 to 60 “preferable lower limit value (10)” and “more preferable upper limit value (60)” can be combined to form “10 to 60”.
  • the grease composition of the present invention is a grease composition used for a speed reducer and a speed increaser, containing a base oil (A), and nanofibers (B) having a thickness (d) of 1 to 500 nm, wherein the nanofibers (B) are one or more selected from cellulose nanofibers (B1) and modified cellulose nanofibers (B2).
  • the thickness (d) of the nanofibers (B) contained in the grease composition is defined.
  • the thickness (d) of the nanofibers (B) dispersed in the base oil (A) is defined.
  • the nanofibers (B) can readily form a higher-order structure in the base oil (A).
  • the nanofibers (B) are easily uniformly dispersed in the base oil (A).
  • the content of the nanofibers (B) is small, it is possible to obtain a grease composition that can be easily adjusted to an appropriate worked penetration and is excellent in both leakage prevention performance and energy transfer efficiency.
  • base oil (A) and “nanofibers (B)” are also referred to as “component (A)” and “component (B)”, respectively.
  • cellulose nanofibers (B1)” and “modified cellulose nanofibers (B2)” are also referred to as “component (B1)” and “component (B2)”, respectively.
  • the total content of the component (A) and the component (B) is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and yet still more preferably 80% by mass or more, based on the total amount (100% by mass) of the grease composition.
  • the upper limit value of the total content of the component (A) and the component (B) may be adjusted in relation to the content of additives other than the component (B), and is preferably 99% by mass or less, more preferably 95% by mass or less, and still more preferably 92% by mass or less.
  • the base oil (A) contained in the grease composition of the present invention is not particularly limited, and examples thereof include mineral oil, synthetic oil, animal oil, vegetable oil, and liquid paraffin.
  • the base oil (A) may be either a base oil composed of a single kind or a mixed base oil of two or more kinds thereof.
  • mineral oil examples include distillate oils obtained through atmospheric distillation of paraffin crude oils, intermediate base crude oils or naphthenic crude oils, or through vacuum distillation of atmospheric distillation residues; refined oils obtained by subjecting such distillate oils to at least one or more refining treatments selected from refining treatments such as solvent deasphalting, solvent extraction, hydrocracking or hydrorefining, as well as refining treatments such as solvent dewaxing or catalytic dewaxing (specifically, a solvent-refined oil, a hydrogenated refined oil, a dewaxing treated oil, a white clay treated oil).
  • refining treatments such as solvent deasphalting, solvent extraction, hydrocracking or hydrorefining
  • refining treatments such as solvent dewaxing or catalytic dewaxing (specifically, a solvent-refined oil, a hydrogenated refined oil, a dewaxing treated oil, a white clay treated oil).
  • mineral oils classified into Group 3 of the base oil category according to API are preferred.
  • Examples of the synthetic oil include hydrocarbon-based oils, aromatic oils, ester-based oils, ether-based oils, and fatty acid esters.
  • hydrocarbon-based oil examples include a normal paraffin, an isoparaffin, a poly-a-olefin (PAO), such as polybutene, polyisobutylene, a 1-decene oligomer, a co-oligomer of 1-decene and ethylene, and hydrides thereof.
  • PAO poly-a-olefin
  • GTL synthetic oil obtained by isomerizing a wax (GTL wax (Gas To Liquids WAX)) produced by the Fischer-Tropsch process or the like is also included.
  • aromatic oil examples include alkylbenzenes, such as a monoalkylbenzene and a dialkylbenzene; and alkylnaphthalenes, such as a monoalkylnaphthalene, a dialkylnaphthalene, and a polyalkylnaphthalenes.
  • ester-based oil examples include diester-based oils, such as dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl glutarate, and methyl acetyl ricinoleate; aromatic ester-based oils, such as trioctyl trimellitate, tridecyl trimellitate, and tetraoctyl pyromellitate; polyol ester-based oils, such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethyl hexanoate, and pentaerythritol pelargonate; and complex ester-based oils, such as an oligo ester between a polyhydric alcohol and a mixed fatty acid of a dibasic acid and a
  • ether-based oil examples include polyglycols, such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, and polypropylene glycol monoether; and phenyl ether-based oils, such as a monoalkyl triphenyl ether, an alkyl diphenyl ether, a dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, a monoalkyl tetraphenyl ether, and a dialkyl tetraphenyl ether.
  • polyglycols such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, and polypropylene glycol monoether
  • phenyl ether-based oils such as a monoalkyl triphenyl ether, an alkyl diphenyl ether, a dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, a monoalky
  • the fatty acid that constitutes the fatty acid ester is preferably a fatty acid having 8 to 22 carbon atoms, and specifically, examples thereof include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, erucic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, isostearic acid, arachidic acid, ricinoleic acid, and 12-hydroxystearic acid.
  • examples of the fatty acid ester include a glycerin fatty acid ester, a polyglycerin fatty acid ester, and a propylene glycol fatty acid ester.
  • glycerin fatty acid ester examples include glycerin monooleate, glycerin monostearate, glycerin monocaprylate, glycerin dioleate, glycerin distearate, and glycerin dicaprylate.
  • polyglycerin fatty acid ester examples include diglycerin monooleate, diglycerin monoisostearate, diglycerin dioleate, diglycerin trioleate, diglycerin monostearate, diglycerin distearate, diglycerin tristearate, diglycerin triisostearate, diglycerin monocaprylate, diglycerin dicaprylate, diglycerin tricaprylate, triglycerin monooleate, triglycerin dioleate, triglycerin trioleate, triglycerin tetraoleate, triglycerin monostearate, triglycerin distearate, triglycerin tristearate, triglycerin tetrastearate, triglycerin monocaprylate, triglycerin dicaprylate, triglycerin tricaprylate, triglycerin tetracaprylate, diglycerin
  • propylene glycol fatty acid ester examples include propylene glycol monooleate, propylene glycol monostearate, propylene glycol monocaprylate, and propylene glycol monolaurate.
  • the vegetable oil is a plant-derived oil, and specifically, examples thereof include rapeseed oil, peanut oil, corn oil, cottonseed oil, canola oil, soybean oil, sunflower oil, palm oil, coconut oil, safflower oil, camellia oil, olive oil, and groundnut oil.
  • the animal oil is an animal-derived oil, and specifically, examples thereof include lard, neat's foot oil, chrysalis oil, sardine oil, and herring oil.
  • liquid paraffin examples include alicyclic hydrocarbon compounds having a branched structure or a ring structure and represented by C m H n (m is number of carbon atoms, provided that n ⁇ (2m+2)), and mixtures thereof.
  • the base oil (A) contained in the grease composition according to one embodiment of the present invention preferably contains one or more selected from mineral oils classified into Group 3 of the base oil category according to API, synthetic oils, vegetable oils, animal oils, fatty acid esters, and liquid paraffins, and more preferably one or more selected from mineral oils classified into Group 3 of the base oil category according to API and synthetic oils.
  • synthetic oil poly-a-olefin (PAO) is preferably used.
  • a synthetic oil is preferably used, one or more selected from a hydrocarbon-based oil, an ester-based oil, and an ether-based oil are more preferably used, and a hydrocarbon-based oil is still more preferably used.
  • a hydrocarbon-based oil is preferably used.
  • the base oil (A) used in one embodiment of the present invention has a kinematic viscosity at 40° C. (hereinafter also referred to as “40° C. kinematic viscosity”) of preferably 10 to 400 mm 2 /s, more preferably 15 to 300 mm 2 /s, still more preferably 20 to 200 mm 2 /s, and yet still more preferably 20 to 130 mm 2 /s.
  • 40° C. kinematic viscosity preferably 10 to 400 mm 2 /s, more preferably 15 to 300 mm 2 /s, still more preferably 20 to 200 mm 2 /s, and yet still more preferably 20 to 130 mm 2 /s.
  • the base oil (A) used in one embodiment of the present invention may be a mixed base oil obtained by combining a low-viscosity base oil (A1) and a high-viscosity base oil (A2) and adjusting the kinematic viscosity to the aforementioned range.
  • the low-viscosity base oil (A1) has the 40° C. kinematic viscosity of preferably 5 to 150 mm 2 /s, more preferably 7 to 120 mm 2 /s, and still more preferably 10 to 100 mm 2 /s.
  • the high-viscosity base oil (A2) has the 40° C. kinematic viscosity of preferably 200 to 1000 mm 2 /s, more preferably 250 to 800 mm 2 /s, and still more preferably 300 to 600 mm 2 /s.
  • a viscosity index of the base oil (A) that is used in one embodiment of the present invention is preferably 60 or more, more preferably 70 or more, and still more preferably 80 or more.
  • the 40° C. kinematic viscosity and the viscosity index mean values as measured or calculated in conformity with JIS K2283:2000.
  • the content of the base oil (A) contained in the grease composition according to one embodiment of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and yet still more preferably 80% by mass or more, based on the total amount (100% by mass) of the grease composition.
  • the nanofibers (B) contained in the grease composition of the present invention are one or more types selected from cellulose nanofibers (B1) and modified cellulose nanofibers (B2).
  • the nanofibers (B) are uniformly dispersed in the grease composition to form a higher-order structure. Since the nanofibers (B) have excellent mechanical stability, the higher-order structure of the nanofibers (B) is stable against shearing. Therefore, the shear stability of the grease composition is improved, and the grease leakage prevention performance is improved.
  • the worked penetration of the grease composition can be adjusted to an appropriate range. Therefore, the proportion of the base oil (A) in the grease composition can be increased. Thus, the lubricity of the grease composition is enhanced, and the energy transfer efficiency is also easily improved.
  • the cellulose nanofibers mean a fibrous material having a thickness of 500 nm or less, which is produced by defibrating plant fibers to a nano level, and is distinguished from a flaky material, a powdery material, and a granular material.
  • lignocellulose As a raw material for cellulose nanofibers, lignocellulose is also usable. It is known that lignocellulose is a composite hydrocarbon polymer that constitutes a cell wall of plants, and is mainly composed of polysaccharides of cellulose and hemicellulose and an aromatic polymer of lignin.
  • the cellulose that constitutes cellulose nanofibers may be one or more selected from lignocellulose and acetylated lignocellulose.
  • Cellulose nanofibers may contain one or more selected from hemicellulose and lignin. Further, the cellulose to constitute cellulose nanofibers may chemically bond to one or more selected from hemicellulose and lignin.
  • the degree of polymerization of cellulose constituting the cellulose nanofibers is preferably 50 to 3000, more preferably 100 to 1500, still more preferably 150 to 1000, and yet still more preferably 200 to 800.
  • the degree of polymerization of cellulose means a value as measured by a viscosity method.
  • the modified cellulose nanofibers are obtained by subjecting cellulose nanofibers to a modification treatment.
  • modification treatment examples include esterification such as acetylation, phosphorylation, urethanization, carbamidation, etherification, carboxymethylation, TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl radical) oxidation, and periodate oxidation.
  • esterification such as acetylation, phosphorylation, urethanization, carbamidation, etherification, carboxymethylation, TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl radical) oxidation, and periodate oxidation.
  • modified cellulose nanofibers used in the present invention may be subjected to only one of these modification treatments, or may be subjected to two or more of these modification treatments.
  • resin-reinforced fibers containing one or more types selected from cellulose nanofibers and modified cellulose nanofibers and a thermoplastic resin are known. Such resin-reinforced fibers are also included in the modified cellulose nanofibers.
  • thermoplastic resin and one or more types selected from the cellulose nanofibers and the modified cellulose nanofibers may be mixed or kneaded, or may be dispersed in each other.
  • thermoplastic resin examples include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinylidene chloride, fluororesin, (meth)acrylic resin, polyamide resin, polyester, polylactic acid resin, polylactic acid/polyester copolymer resin, acrylonitrile-butadiene-styrene copolymer, polycarbonate, polyphenylene oxide, (thermoplastic) polyurethane, polyacetal, vinyl ether resin, polysulfone resin, and cellulose resin (e.g., triacetylated cellulose, diacetylated cellulose).
  • (meth)acryl means acryl and/or methacryl.
  • thermoplastic resin may be used alone or in combination of two or more kinds thereof.
  • the definition of the “thickness” of the nanofibers (B) is the same as the definition relating to the thickness of a general fibrous material.
  • the diameter or major axis is the “thickness” of the nanofibers (B).
  • the diameter of the circumscribed circle of the polygon is the “thickness” of the nanofibers (B).
  • micro-size particles When the base oil (A) is blended with a flaky substance, a powdery substance or a granular substance having a size of several ⁇ m or more (hereinafter also referred to as “micro-size particles”) as a thickener, the micro-size particles tend to aggregate in the base oil (A) to form a so-called “lump”. As a result, an aggregate of the micro-size particles is deposited on the surface of the obtained grease composition, and the dispersed state is liable to become non-uniform. In this case, it is necessary to add a large amount of the micro-size particles in order to increase the worked penetration of the obtained grease composition. However, as containing particles larger than the oil film thickness, the resultant grease composition becomes inferior in wear resistance.
  • the nanofibers (B) having a thickness (d) of 1 to 500 nm are blended in the base oil (A), the nanofibers (B) do not aggregate in the base oil (A), and a higher-order structure is formed by the nanofibers (B) while the nanofibers (B) are uniformly dispersed.
  • the content of the nanofibers (B) is small, a grease composition having an appropriate worked penetration can be obtained.
  • the “thickness (d) of the nanofibers (B)” indicates the thickness of the nanofibers (B) dispersed in the base oil (A), and is distinguished from the “thickness (d′) of the nanofibers (B)” as a raw material prior to being blended in the base oil (A).
  • the thickness (d) of the nanofibers (B) dispersed in the base oil (A) is 1 to 500 nm, but is preferably 1 to 300 nm, more preferably 1 to 200 nm, and still more preferably 2 to 100 nm from the viewpoint of forming a higher-order structure by the nanofibers (B) and from the viewpoint of more uniformly dispersing the nanofibers (B) in the base oil (A).
  • nanofibers (B) contained in the grease composition of the present invention it is sufficient to confirm dispersion of the nanofibers (B) having a thickness (d) within the aforementioned range, and the nanofibers (B) having a thickness (d) outside the aforementioned range may be dispersed.
  • the average value of the thickness (d) of ten nanofibers (B) arbitrarily selected from the nanofibers (B) dispersed in the base oil (A) is preferably 1 to 500 nm, more preferably 1 to 300 nm, still more preferably 1 to 200 nm, and yet still more preferably 2 to 100 nm.
  • the number of the nanofibers (B) whose thickness (d) falls within the aforementioned range is preferably 1 or more, more preferably 5 or more, and still more preferably 7 or more. It is more preferred that all of the ten selected nanofibers (B) are the nanofibers (B) having a thickness (d) falling within the aforementioned range.
  • an aspect ratio of the nanofibers (B) is preferably 5 or more, more preferably 10 or more, still more preferably 15 or more, yet still more preferably 30 or more, even more preferably 50 or more, yet even more preferably 70 or more, further more preferably 90 or more, and yet further more preferably 100 or more.
  • the “aspect ratio” refers to a ratio of a length to a thickness (length/thickness) of the nanofiber (B) to be observed, and the “length” of the nanofiber (B) refers to a distance between the two most distant points of the nanofiber (B).
  • the length of only a part of the nanofiber (B) to be observed in which the thickness can be measured may be measured and the aspect ratio of the part may be in the aforementioned range.
  • an average value of the aspect ratio (hereinafter also referred to as “average aspect ratio”) of ten arbitrarily selected nanofibers (B) is preferably 5 or more, more preferably 10 or more, still more preferably 15 or more, yet still more preferably 30 or more, even more preferably 50 or more, yet even more preferably 70 or more, further more preferably 90 or more, and yet further more preferably 100 or more.
  • the thickness (d′) of the nanofibers (B) as a raw material prior to being blended in the base oil (A) is preferably 1 to 500 nm, more preferably 1 to 300 nm, still more preferably 1 to 200 nm, and yet still more preferably 2 to 100 nm.
  • the average aspect ratio of the nanofibers (B) as a raw material prior to mixing with the base oil (A) is preferably 5 or more, more preferably 10 or more, still more preferably 15 or more, yet still more preferably 30 or more, even more preferably 50 or more, yet even more preferably 70 or more, further more preferably 90 or more, and yet further more preferably 100 or more.
  • the “thickness (d)” of the nanofibers (B) dispersed in the base oil (A) and the “thickness (d′)” of the nanofibers (B) as a raw material prior to being blended in the base oil (A) as well as the aspect ratio of these nanofibers (B) each are a value as measured using an electron microscope or the like.
  • the worked penetration is adjusted to an appropriate range even when the content of the nanofibers (B) is small.
  • the content of the nanofibers (B) is preferably 0.1 to 20% by mass, more preferably 0.5 to 18% by mass, still more preferably 0.8 to 15% by mass, yet still more preferably 1.0 to 12% by mass, even more preferably 1.0 to 10% by mass, and yet even more preferably 1.0 to 9.0% by mass, based on the total amount (100% by mass) of the grease composition.
  • the worked penetration of the grease composition is also easily adjusted to an appropriate range.
  • the grease composition according to one embodiment of the present invention preferably further contains an organic bentonite (C) in addition to the base oil (A) and the nanofibers (B).
  • the nanofibers (B) preferably contain cellulose nanofibers (B1).
  • the nanofibers (B) are uniformly dispersed in the grease composition to form a higher-order structure.
  • the nanofibers (B) contain cellulose nanofibers (B1)
  • the cellulose nanofibers (B1) are also uniformly dispersed in the grease composition to form a higher-order structure.
  • the organic bentonite (C) is dispersed in the vicinity of the cellulose nanofibers (B1) that are uniformly dispersed because the hydrophilic surface (the surface having a hydrophilic group) adsorbs the hydrophilic group of the cellulose nanofibers (B1) or the hydrophilic surface thereof comes close to the hydrophilic group of the cellulose nanofibers (B1).
  • the organic bentonite (C) is uniformly dispersed and arranged as if it surrounds the hydrophilic group of the cellulose nanofibers (B1).
  • the nanofibers (B) have excellent mechanical stability.
  • the cellulose nanofibers (B1) also have excellent mechanical stability.
  • the organic bentonite (C) also has excellent mechanical stability. Therefore, the higher-order structure of the nanofibers (B) (cellulose nanofibers (B1)) and the organic bentonite (C) dispersed in the grease composition are stable against shearing. Therefore, the shear stability of the grease composition is improved, and the grease leakage prevention performance is improved.
  • the cellulose nanofibers (B1) and the organic bentonite (C) are easily uniformly dispersed in the base oil (A), a grease composition having an appropriate worked penetration can be obtained even when the content of the cellulose nanofibers (B1) is small and the content of the organic bentonite (C) is also small, and thus the proportion of the base oil (A) in the grease composition can be increased.
  • the lubricity of the grease composition is enhanced, and the energy transfer efficiency is also easily improved.
  • the organic bentonite (C) is uniformly dispersed and arranged to surround the hydrophilic group of the cellulose nanofibers (B1), which pseudo-hydrophobizes the cellulose nanofibers (B1) and provides excellent water resistance to the grease composition.
  • the content of the organic bentonite (C) is small means that the content of the organic bentonite (C) is 0.01 to 15% by mass, preferably 0.1 to 10% by mass, and more preferably 1.0 to 8.0% by mass, based on the total amount (100% by mass) of the grease composition.
  • the content of the cellulose nanofibers (B1) is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, still more preferably 80 to 100% by mass, and yet still more preferably 90 to 100% by mass, based on the total amount of the nanofibers (B), from the viewpoint of maximizing the effect obtained by containing the organic bentonite (C).
  • the total content of the base oil (A), the nanofibers (B), and the organic bentonite (C) is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, yet still more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total amount (100% by mass) of the grease composition.
  • the content ratio [(B1)/(C)] of the cellulose nanofibers (B1) to the organic bentonite (C) is preferably 0.05 to 5.0, more preferably 0.1 to 2.0, and still more preferably 0.1 to 1.0, in terms of mass ratio, from the viewpoint of obtaining a grease composition that is more excellent in leakage prevention performance and energy transfer efficiency as well as excellent in water resistance.
  • the organic bentonite (C) is one prepared by modifying the crystal surface of a clay mineral, montmorillonite through treatment with a quaternary ammonium compound.
  • the quaternary ammonium compound may be any one capable of modifying the crystal surface of a clay mineral, montmorillonite, and examples thereof include dimethylalkylammonium such as dimethyldioctadecylammonium; trimethylalkylammonium such as trimethyloctadecylammonium; and trialkylbenzylammonium. Among these, dimethylalkylammonium such as dimethyldioctadecylammonium is preferred.
  • the quaternary ammonium compound may be used alone or in combination of two or more kinds thereof.
  • organic bentonite (C) may be used alone or in combination of two or more kinds thereof.
  • the organic bentonite (C) is cleaved when subjected to shear in the presence of a polar compound in a base oil and functions as a thickener.
  • bentonite such as an organic bentonite is difficult to uniformly disperse in a base oil. Consequently, in general, a large amount of bentonite is blended in a grease composition using bentonite as a thickener (bentonite grease) to control the worked penetration of the composition.
  • bentonite is generally blended in an amount of 18% by mass or more, further 20% by mass or more, relative to the total amount (100% by mass) of the grease composition.
  • the grease composition according to one embodiment of the present invention enables the organic bentonite (C) to be uniformly dispersed in the base oil by using the cellulose nanofibers (B1) and the organic bentonite (C) in combination.
  • a method for producing an organic bentonite is disclosed in detail, for example, in JP 62-83108 A and JP 53-72792 A.
  • the grease composition according to one embodiment of the present invention may further contain various additives that are blended in general greases composition within a range where the effects of the present invention are not impaired.
  • Examples of the various additives include an extreme pressure agent, a rust inhibitor, an antioxidant, a detergent dispersant, a corrosion inhibitor, an anti-foaming agent, and a metal deactivator.
  • the grease composition according to one embodiment of the present invention may contain a dispersant and water used in grease formation within a range where the grease state may be maintained.
  • Examples of the dispersant include compounds exemplified in the method for producing the grease composition of the present invention described later.
  • the total content of the dispersant and water is preferably 0 to 60% by mass, more preferably 0 to 30% by mass, still more preferably 0 to 10% by mass, and yet still more preferably 0 to 5% by mass, based on the total amount (100% by mass) of the grease.
  • extreme pressure agent examples include one or more selected from a phosphorus extreme pressure agent and a sulfur-phosphorus extreme pressure agent.
  • Examples of the phosphorus extreme pressure agent include one or more phosphates selected from orthophosphate, hydrogen phosphate, polyphosphate, phosphite, and metaphosphate.
  • polyphosphate examples include pyrophosphate (diphosphate), tripolyphosphate, and tetrapolyphosphate.
  • the phosphate is preferably an alkali metal salt.
  • the alkali metal salt include a sodium salt, a potassium salt and a lithium salt, and a sodium salt is particularly preferable.
  • sulfur-phosphorus extreme pressure agent examples include one or more selected from a thiophosphoric acid ester and an amine salt of a thiophosphoric acid ester.
  • thiophosphoric acid ester examples include a monothiophosphoric acid ester, a dithiophosphoric acid ester, a trithiophosphoric acid ester, a monothiophosphorous acid ester, a dithiophosphorous acid ester, and a trithiophosphorous acid ester, and among these, a trithiophosphoric acid ester is preferable.
  • trithiophosphoric acid ester examples include trialkyl phosphorothionates such as tributyl phosphorothionate, tripentyl phosphorothionate, trihexyl phosphorothionate, triheptyl phosphorothionate, trioctyl phosphorothionate, trinonyl phosphorothionate, tridecyl phosphorothionate, triundecyl phosphorothionate, tripentadecyl phosphorothionate, and trihexadecyl phosphorothionate; triaryl phosphorothionates such as triphenyl phosphorothionate, tricresyl phosphorothionate, and trixylenyl phosphorothionate; and tris(alkylphenyl)phosphorothionates such as tris(n-propylphenyl)phosphorothionate, tris(isopropylphenyl)phosphorothionate
  • Examples of the amine salt of the thiophosphoric acid ester include the amine salts of the thiophosphoric acid esters exemplified above.
  • the content of the extreme pressure agent contained in the grease composition according to one embodiment of the present invention is preferably 0.01 to 5.0% by mass, more preferably 0.1 to 3.0% by mass, and still more preferably 0.5 to 2.0% by mass, based on the total amount (100% by mass) of the grease composition.
  • Examples of the extreme pressure agent other than the aforementioned extreme pressure agent include organic molybdenum.
  • the grease composition according to one embodiment of the present invention preferably has a low content of molybdenum atoms.
  • the content of molybdenum atoms is preferably less than 50 ppm % by mass, more preferably less than 10 ppm % by mass, still more preferably less than 1 ppm % by mass, and yet still more preferably no molybdenum atoms, based on the total amount (100% by mass) of the grease composition.
  • rust inhibitor examples include a carboxylic acid-based rust inhibitor, an amine-based rust inhibitor, and a carboxylate-based rust inhibitor.
  • the content of the rust inhibitor is preferably 0.1 to 10.0% by mass, more preferably 0.3 to 8.0% by mass, and still more preferably 1.0 to 5.0% by mass, based on the total amount (100% by mass) of the grease composition.
  • antioxidant examples include an amine-based antioxidant, a phenol-based antioxidant, a sulfur-based antioxidant, and zinc dithiophosphate.
  • the content of the antioxidant is preferably 0.05 to 10% by mass, more preferably 0.1 to 7% by mass, and still more preferably 0.2 to 5% by mass, based on the total amount (100% by mass) of the grease composition.
  • detergent dispersant examples include a succinimide, and a boron-based succinimide.
  • Examples of the corrosion inhibitor include a benzotriazole-based compound, and a thiazole-based compound.
  • anti-foaming agent examples include a silicone-based compound, and a fluorinated silicone-based compound.
  • metal deactivator examples include benzotriazole.
  • the content of each of these additives is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and still more preferably 0.2 to 5% by mass, based on the total amount (100% by mass) of the grease composition.
  • the worked penetration at 25° C. of the grease composition according to one embodiment of the present invention is preferably 220 to 440, more preferably 240 to 400, still more preferably 250 to 380, and yet still more preferably 270 to 360.
  • the grease composition according to one embodiment of the present invention is a grease composition that is excellent in the leakage prevention performance of the grease composition and is excellent in the energy transfer efficiency and the leakage prevention performance even when the worked penetration at 25° C. is adjusted to the aforementioned range.
  • the change in worked penetration in a roll stability test measured and calculated by the method described in Examples below is preferably 50 or less, more preferably 40 or less, still more preferably 30 or less, and yet still more preferably 20 or less.
  • the grease composition according to one embodiment of the present invention has a torque transmission efficiency, which is an index of energy transfer efficiency, of preferably 60.0% or more, more preferably 63.0% or more, and still more preferably 66.0% or more, as measured and calculated by the method described in Examples below.
  • the method for producing the grease composition of the present invention is not particularly limited, but includes, for example, the following step (1), and the step (2) is performed as necessary.
  • Step (1) a step of preparing a liquid mixture in which nanofibers (B) having a thickness (d′) of 1 to 500 nm are dispersed in a base oil (A).
  • Step (2) a step of removing an unnecessary component from the liquid mixture.
  • the nanofibers (B) are one or more types selected from cellulose nanofibers (B1) and modified cellulose nanofibers (B2).
  • the aggregation of the nanofibers (B) is suppressed, and the nanofibers having a thickness (d) of 1 to 500 nm can be dispersed in the base oil (A) while maintaining the fiber shape.
  • a higher-order structure is formed by the nanofibers (B) in the base oil, and the nanofibers (B) can be uniformly dispersed in the base oil (A). Therefore, by adding a small amount of the nanofibers (B), a grease composition having an appropriate worked penetration can be prepared, and a grease composition excellent in both leakage prevention performance and energy transfer efficiency can be obtained.
  • the step (S1a) is a step of preparing a liquid mixture in which nanofibers (B) having a thickness (d′) of 1 to 500 nm are dispersed in a base oil (A).
  • nanofibers (B) and the base oil (A) used in the step (S1a) are as described above.
  • the “thickness (d′)” as referred to herein expresses the thickness of the nanofibers (B) as a raw material prior to being blended in the base oil (A) as described above, and a preferred range of the “thickness (d′)” is the same as described above.
  • nanofibers (B) powdered cellulose nanofibers dispersible in water, an organic solvent, or the base oil (A) may be used, or a dispersion in which the nanofibers are dispersed in water, an organic solvent, or the base oil (A) may be used.
  • nanofibers may be formed by applying shear in the base oil (A).
  • the solid content concentration of the dispersion having the nanofibers (B) blended therein is usually 0.1 to 70% by mass, preferably 0.1 to 65% by mass, more preferably 0.1 to 60% by mass, still more preferably 0.5 to 55% by mass, and yet still more preferably 1.0 to 50% by mass, based on the total amount (100% by mass) of the dispersion.
  • the dispersion can be prepared by blending the nanofibers (B) in water or an organic solvent, optionally blending a dispersant or the like when the aqueous dispersion is used, and sufficiently stirring the mixture manually or with a stirrer.
  • the dispersant is preferably one or more selected from aprotic polar solvents, such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); alcohols, such as propanol, ethylene glycol, propylene glycol, and hexylene glycol; and surfactants, such as a polyglycerin fatty acid ester, a sucrose fatty acid ester, a citric acid monoglyceride, a diacetyltartaric acid monoglyceride, a polyoxyethylene sorbitan acid ester, and sorbitan acid ester.
  • aprotic polar solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP)
  • alcohols such as propanol, ethylene glycol, propylene glycol, and hexy
  • the blending amount of the dispersant in the liquid mixture that is prepared in the step (Sla) is preferably 0.1 to 50% by mass, more preferably 0.5 to 40% by mass, still more preferably 1.0 to 30% by mass, yet still more preferably 1.0 to 20% by mass, and even more preferably 1.0 to 10% by mass, based on the total amount (100% by mass) of the liquid mixture.
  • the blending amount of water or the organic dispersion in the liquid mixture that is prepared in the step (S1a) is preferably 1 to 60% by mass, more preferably 3 to 50% by mass, and still more preferably 5 to 40% by mass, based on the total amount (100% by mass) of the liquid mixture.
  • the blending ratio of water to the dispersion medium (water/dispersion medium) in the liquid mixture that is prepared in the step (S1a) is preferably 0.01 to 600, more preferably 0.05 to 400, still more preferably 0.1 to 300, and yet still more preferably 0.2 to 200 in terms of mass ratio.
  • a liquid mixture in which the nanofibers (B) having a thickness (d′) of 1 to 500 nm are dispersed in the base oil (A) can be prepared.
  • the liquid mixture in which the nanofibers (B) having a thickness (d′) of 1 to 500 nm are dispersed in the base oil (A) can also be prepared by directly dispersing the nanofibers (B) in the base oil (A) or by applying shear to a nanofiber raw material in the base oil (A) to form nanofibers.
  • the step (2) is a step of removing an unnecessary component from the liquid mixture prepared in the step (1).
  • the unnecessary component is one or more selected from water, an organic solvent, and a dispersant in the liquid mixture.
  • a method for removing one or more selected from water, an organic solvent, and a dispersant in the liquid mixture a method of heating the liquid mixture and evaporating and removing the same is preferable.
  • the temperature range in consideration of the boiling point of one or more selected from an organic solvent and a dispersant in an environment at a pressure of 0.001 to 0.1 MPa, and to heat.
  • the heating temperature is, for example, 0 to 100° C.
  • a grease composition is prepared.
  • the organic bentonite (C) and further other additives may be mixed in the liquid mixture in the step (1), or may be mixed in the grease composition prepared in the step (2) and then subjected to a treatment such as homogenization using a roll mill or the like.
  • the grease composition of the present invention is excellent in both leakage prevention performance and energy transfer efficiency.
  • the grease composition according to one embodiment of the present invention can be suitably used for a speed reducer included in an industrial robot or the like and a speed increaser included in a wind power generation facility.
  • Examples of the speed reducer and the speed increaser include a speed reducer including a gear mechanism and a speed increaser including a gear mechanism.
  • the object to which the grease composition according to one embodiment of the present invention is applied is not limited to a speed reducer including a gear mechanism and a speed increaser including a gear mechanism, and the grease composition can also be applied to, for example, a traction drive or the like.
  • a speed reducer or a speed increaser having the grease composition of the present invention at a lubricating portion.
  • a lubricating method for lubricating a lubricating portion of a speed reducer or a speed increaser with the grease composition of the present invention is provided.
  • the nanofibers (B) have a low environmental load and are excellent in safety for human bodies. Therefore, the grease composition of the present invention can be suitably used for a food machine including a speed reducer, a food machine including a speed increaser, and the like.
  • the organic bentonite (C) also has a low environmental load and is excellent in safety for human bodies. Therefore, the grease composition according to one embodiment of the present invention containing the organic bentonite (C) can also be suitably used for a food machine including a speed reducer, a food machine including a speed increaser, and the like.
  • a food machine including a speed reducer or a speed increaser having the grease composition of the present invention at a lubricating portion.
  • a lubrication method including lubricating a lubricating portion of a food machine including a speed reducer or a speed increaser with the grease composition of the present invention.
  • hydrophilic nanofibers were each measured with respect to the thickness and the length thereof by using a transmission electron microscope (TEM), and a value as calculated from “length/thickness” was defined as an “aspect ratio” of the hydrophilic nanofibers measured.
  • TEM transmission electron microscope
  • a low-viscosity base oil (A1) and a high-viscosity base oil (A2) were combined to prepare a mixed base oil having a 40° C. kinematic viscosity of 60 mm 2 /s and a viscosity index of 135.
  • a grease composition having a formulation shown in Example 3 of Table 1 was prepared under the same conditions as in Example 2 except that the phosphorus extreme pressure agent was not added and the blending amount of the base oil (A) was changed to 85.8 parts by mass.
  • a grease composition having a formulation shown in Example 5 of Table 1 was prepared under the same conditions as in Example 3 except that the sulfur-phosphorus extreme pressure agent was not added and the blending amount of the base oil (A) was changed to 86.3 parts by mass.
  • the grease compositions thus prepared were evaluated as follows.
  • the change in penetration in the roll stability test was measured by the method described in ASTM D 1831. However, the temperature and time were changed to 80° C. and 20 hours, respectively.
  • FIG. 1 is a schematic view of an apparatus used for measuring torque transmission efficiency as an index of energy transfer efficiency in this embodiment.
  • the measuring apparatus 100 shown in FIG. 1 is formed by connecting an input side motor unit 111 , an input side torque measuring device 112 , an input side speed reducer 113 (manufactured by Harmonic Drive Systems Inc., product name “CSG-40-100-2UH”), an output side torque measuring device 122 , an output side speed reducer 123 (manufactured by Nabtesco Corporation, product name “RV-125V”), and an output side motor unit 121 in this order.
  • a grease-filled case (case internal temperature: 30° C.) included in the input side speed reducer 113 of the measuring apparatus 1 shown in FIG. 1 was filled with 140 g of a mixed grease, the measuring apparatus 100 was operated under conditions of a load torque of 240 Nm and an input side rotation speed of 1600 rpm, the rotation speeds and torques on the input side and the output side were measured, the torque transmission efficiency was calculated from the following equation (1), and the energy transfer efficiency was evaluated.
  • the reduction ratio is 100.
  • the torque transmission efficiency is an index indicating an amount of loss until input energy is output.
  • a lower torque transmission efficiency means a larger energy loss, and a higher torque transmission efficiency means a smaller energy loss.
  • the grease composition in which the organic bentonite is blended without blending the nanofibers (B) as in the grease composition of Comparative Example 1 has an appropriate worked penetration, but is inferior in shear stability and energy transfer efficiency.

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  • General Chemical & Material Sciences (AREA)
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  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Dispersion Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Lubricants (AREA)
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WO2024203765A1 (ja) * 2023-03-31 2024-10-03 出光興産株式会社 グリース組成物

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