US20030013622A1 - Bearing grease composition - Google Patents
Bearing grease composition Download PDFInfo
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- US20030013622A1 US20030013622A1 US10/207,096 US20709602A US2003013622A1 US 20030013622 A1 US20030013622 A1 US 20030013622A1 US 20709602 A US20709602 A US 20709602A US 2003013622 A1 US2003013622 A1 US 2003013622A1
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- Prior art keywords
- grease composition
- carbonate
- oil
- bearing
- component
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- 0 *OC(=O)OC Chemical compound *OC(=O)OC 0.000 description 4
- QWTDNUCVQCZILF-UHFFFAOYSA-N CCC(C)C Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 description 3
- VXKYGWKYEDABRI-UHFFFAOYSA-N CCCCCCCCCCCCC1(C)CO1C(=O)OC1(CCCCCCCCCCC)CC1 Chemical compound CCCCCCCCCCCCC1(C)CO1C(=O)OC1(CCCCCCCCCCC)CC1 VXKYGWKYEDABRI-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
- 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
- C10M169/02—Mixtures of base-materials and thickeners
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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
- C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
- C10M105/08—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing oxygen
- C10M105/32—Esters
- C10M105/48—Esters of carbonic acid
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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
- C10M117/00—Lubricating compositions characterised by the thickener being a non-macromolecular carboxylic acid or salt thereof
- C10M117/02—Lubricating compositions characterised by the thickener being a non-macromolecular carboxylic acid or salt thereof having only one carboxyl group bound to an acyclic carbon atom, cycloaliphatic carbon atom or hydrogen
- C10M117/04—Lubricating compositions characterised by the thickener being a non-macromolecular carboxylic acid or salt thereof having only one carboxyl group bound to an acyclic carbon atom, cycloaliphatic carbon atom or hydrogen containing hydroxy groups
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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
- 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
- C10M2207/121—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of seven or less carbon atoms
- C10M2207/124—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of seven or less carbon atoms containing hydroxy groups; Ethers thereof
- C10M2207/1245—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of seven or less carbon atoms containing hydroxy groups; Ethers thereof used as thickening agent
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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
- 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
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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
- 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
- C10M2207/128—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 containing hydroxy groups; Ethers thereof
- C10M2207/1285—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 containing hydroxy groups; Ethers thereof used as thickening agents
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- 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
- C10M2207/32—Esters of carbonic acid
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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
- C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
- C10M2207/28—Esters
- C10M2207/32—Esters of carbonic acid
- C10M2207/325—Esters of carbonic acid used as base material
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- C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
- C10N2010/00—Metal present as such or in compounds
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- C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
- C10N2010/00—Metal present as such or in compounds
- C10N2010/02—Groups 1 or 11
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- 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
- C10N2010/00—Metal present as such or in compounds
- C10N2010/04—Groups 2 or 12
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- 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
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- 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
- C10N2040/14—Electric or magnetic purposes
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- 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
- C10N2040/14—Electric or magnetic purposes
- C10N2040/16—Dielectric; Insulating oil or insulators
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- 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
- C10N2040/14—Electric or magnetic purposes
- C10N2040/17—Electric or magnetic purposes for electric contacts
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- 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
- C10N2040/14—Electric or magnetic purposes
- C10N2040/175—Pantographs, i.e. printing devices
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- 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
- C10N2040/14—Electric or magnetic purposes
- C10N2040/18—Electric or magnetic purposes in connection with recordings on magnetic tape or disc
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- 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
- C10N2040/14—Electric or magnetic purposes
- C10N2040/185—Magnetic fluids
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- 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
- C10N2040/30—Refrigerators lubricants or compressors lubricants
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- 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
- C10N2040/32—Wires, ropes or cables lubricants
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- 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
- C10N2040/34—Lubricating-sealants
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- 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
- C10N2040/36—Release agents or mold release agents
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- 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
- C10N2040/38—Conveyors or chain belts
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- 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
- C10N2040/40—Generators or electric motors in oil or gas winning field
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- 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
- C10N2040/42—Flashing oils or marking oils
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- 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
- C10N2040/44—Super vacuum or supercritical use
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- 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
- C10N2040/50—Medical uses
Definitions
- the present invention relates to a bearing grease composition for hard disc drive or the like. More particularly, the invention relates to a bearing grease composition for spindle motors which are used under clean environment, as in memories such as hard disc drive (HDD) or floppy disc drive (FDD) in computers.
- HDD hard disc drive
- FDD floppy disc drive
- a sodium complex soap-based grease comprising a mineral oil as a base oil or a lithium soap-based grease comprising as a base oil, a synthetic ester (diester oil or polyol ester oil) which is a reaction product of an organic acid and an alcohol has conventionally been used as HDD bearing grease.
- a synthetic ester diester oil or polyol ester oil
- the sodium complex soap-based grease comprising a mineral oil as a base oil has been used for a long time with appreciation that the amount of scatter is small.
- the grease had the problems that dispersion of a thickening agent in the grease is poor, and it is difficult to form a homogeneous mixture, so that acoustic and vibrating performances during evolution of the bearing is not good; moisture absorption is high, and the grease cures with the passage of time, so that flowability of the grease in the bearing becomes poor, causing defective lubrication.
- the lithium soap-based grease comprising as a base oil, a synthetic ester (diester or polyol ester oil) which is a reaction product of an organic acid and an alcohol had no problem due to that dispersibility of the lithium soap is good, and low torque property was good.
- the lithium soap-based grease tends to scatter, and if the grease is used as it is, there is the great possibility to damage a hard disc. Therefore, in order to prevent the damage, the grease is used in combination with an expensive magnetic fluid seal which is used in a motor. This rather results in increase of cost of a motor and prevents the motor from being miniaturized. Further, for example, due to the demand of high speed revolution and high precision of the motor, this grease does not sufficiently withstand acoustic performance and torque, disorder has sometimes occurred in acoustic performance or torque.
- an object of the present invention is to provide a grease composition which can maintain stable low torque property, low noise property and low scatter property even at high speed revolution.
- a bearing grease composition comprising:
- R and R′ which may be the same or different, each represent a branched alkyl group having 13 to 15 carbon atoms;
- n is a number of 13 to 15 and m is a number of 0 to 6.
- the bearing grease composition of the present invention preferably comprises 70 to 95 parts by weight of component (a) of the carbonate compound, and 5 to 30 parts by weight of component (b) of the alkali metal salt and/or alkaline earth metal salt.
- component (b) of the alkali metal salt and/or alkaline earth metal salt is less than 5 parts by weight, a worked penetration becomes soft, and as a result, the grease composition leaks or scatters during revolution of a bearing, resulting in possibility of contaminating HDD, FDD and the like.
- the bearing grease composition according to the present invention can contain, in addition to the components (a) and (b) described above, lubricants other than the component (a), and various additives, as a third component.
- Examples of the lubricants used in the present invention include mineral oils, synthesized hydrocarbon oils, ether oils and ester oils, which are generally used as a base oil of grease compositions.
- the additives used in the present invention are additives generally used in grease composition, and the examples thereof include antioxidants and rust inhibitors.
- the grease composition of the present invention may further contain one or more of thickening agents.
- a bearing grease composition preferably comprises:
- R and R′ which may be the same or different each represent a branched alkyl group having 13 to 15 carbon atoms;
- the bearing grease composition comprises:
- R and R′ which may be the same or different, each represent a branched alkyl group having 13 to 15 carbon atoms, wherein the branched alkyl group R and R′ in the carbonate compound represented by the formula (I) is represented by the following formula (II):
- n is a number of 13 to 15 and m is a number of 0 to 6;
- the bearing grease composition comprises 70 to 95 parts by weight of the carbonate compound represented by formulas (I) and (II) and 5 to 30 parts by weight of the member selected from the group consisting of an alkali metal salt and/or an alkaline earth metal salt, synthesized from a hydroxide of an alkali metal or an alkaline earth metal and a higher hydroxyfatty acid having 10 or more carbon atoms or a higher hydroxyfatty acid having at least one hydroxyl group and having 10 or more carbon atoms.
- the bearing grease composition for hard disc drive includes preferably a plurality of carbonate compounds.
- the bearing grease composition further comprises one or more thickening agents.
- the carbonate compound can be used alone or as mixtures thereof.
- R is the branched alkyl group represented by the following formula (IV):
- R′ is the branched alkyl group represented by the following formula (V):
- this carbonate is hereinafter referred to as “carbonate oil A”) alone, or a mixed oil of a carbonate containing commercially available organic carbonate having different structure of an alkyl group (CYCRANT T-394, trade name, a product of Mitsui Petrochemical Industries, Ltd.) (this ester is hereinafter referred to as “carbonate ester oil B”) and the carbonate ester oil A was mixed with lithium stearate and/or lithium 12 hydroxystearate in the proportions as shown in Table 1 such that the sum of those was 100 mass %. The resulting mixture was heated to 220-230° C. while stirring until the whole of mixture became liquid. The liquid thus obtained was poured into a stainless steel vessel at a depth of 3-5 mm. The liquid was cooled at 50° C. or less and then homogenized with three rollers to obtain a grease composition.
- Grease compositions were obtained in the same manner as in Examples 1 to 6 above except that an alkyl diphenyl ether or a polyol ester was further used as a third component other than components (a) and (b) in the proportion as shown in Table 1.
- Grease compositions were obtained in the same manner as in Examples 1-6 except that a base oil and a lithium soap were used in the proportions as shown in Table 2.
- the worked penetration was measured according to JIS K2220, 5.3, and the dropping point was measured according to JIS K2220, 5.4.
- the motor characteristic test was conducted such that a bearing having included therein a grease composition to be tested was incorporated in a spindle motor, the motor was rotated at 10,000 rpm at a normal temperature, and noise generated, amount of evaporation (scatter) and rotating torque were measured.
- Noise was measured with a microphone at a place which is 30 cm apart from a hub edge of the motor during rotation of motor.
- the amount of evaporation (scatter) was determined by the difference between weight of motor before rotation and weight of motor after rotation.
- the torque was determined by measuring electric current value at the rotation of motor with an ammeter, and the torque stability was determined by the difference between the maximum electric current value and the minimum electric current value.
- the bearing grease composition of the present invention shows low evaporation (scatter), low noise, low torque property and stable torque.
Abstract
A bearing grease composition used under clean atmosphere, as in a bearing of hard disc drive, which has small dust generation (scatter), a long life, excellent acoustic performance and low torque.
It has been found that especially the bearing grease composition comprising a carbonate having a branched alkyl group of 13 to 15 carbon atoms and a metallic soap shows remarkable characteristics.
Description
- The present invention relates to a bearing grease composition for hard disc drive or the like. More particularly, the invention relates to a bearing grease composition for spindle motors which are used under clean environment, as in memories such as hard disc drive (HDD) or floppy disc drive (FDD) in computers.
- In general, performances required for a bearing grease composition used in memories, for examples, HDD or FDD in computers are that dust generation (scatter) is low, torque is small, acoustic performance is excellent and life is long. In particular, in HDD used under a clean atmosphere, fine particles of gaseous oil or grease scattered from the inside of a bearing during revolution contaminates the surface of a disc, resulting in cause of wrong operation. Therefore, it is considered to be most important to suppress the amount of scatter.
- A sodium complex soap-based grease comprising a mineral oil as a base oil or a lithium soap-based grease comprising as a base oil, a synthetic ester (diester oil or polyol ester oil) which is a reaction product of an organic acid and an alcohol has conventionally been used as HDD bearing grease.
- The sodium complex soap-based grease comprising a mineral oil as a base oil has been used for a long time with appreciation that the amount of scatter is small. However, the grease had the problems that dispersion of a thickening agent in the grease is poor, and it is difficult to form a homogeneous mixture, so that acoustic and vibrating performances during evolution of the bearing is not good; moisture absorption is high, and the grease cures with the passage of time, so that flowability of the grease in the bearing becomes poor, causing defective lubrication.
- Further, the lithium soap-based grease comprising as a base oil, a synthetic ester (diester or polyol ester oil) which is a reaction product of an organic acid and an alcohol had no problem due to that dispersibility of the lithium soap is good, and low torque property was good.
- However, the lithium soap-based grease tends to scatter, and if the grease is used as it is, there is the great possibility to damage a hard disc. Therefore, in order to prevent the damage, the grease is used in combination with an expensive magnetic fluid seal which is used in a motor. This rather results in increase of cost of a motor and prevents the motor from being miniaturized. Further, for example, due to the demand of high speed revolution and high precision of the motor, this grease does not sufficiently withstand acoustic performance and torque, disorder has sometimes occurred in acoustic performance or torque.
- As a result of extensive investigations to overcome the above-described problems in the prior art, it has been found that properties required for a bearing grease composition which is used under a clean environment as in, for example, memories such as HDD or FDD are satisfied by using a metallic soap-based grease comprising as a base oil a carbonate containing an organic carbonate represented by the formula (I) described hereinafter. The present invention has been completed based on this finding.
- Accordingly, an object of the present invention is to provide a grease composition which can maintain stable low torque property, low noise property and low scatter property even at high speed revolution.
- According to the present invention, there is provided a bearing grease composition comprising:
-
- wherein R and R′, which may be the same or different, each represent a branched alkyl group having 13 to 15 carbon atoms; and
- (b) a group consisting of an alkali metal salt and/or an alkaline earth metal salt, which are synthesized from a hydroxide of an alkali metal or an alkaline earth metal and a higher hydroxyfatty acid having 10 or more carbon atoms or a higher hydroxyfatty acid having at least one hydroxyl group and having 10 or more carbon atoms.
-
- wherein n is a number of 13 to 15 and m is a number of 0 to 6.
-
- The bearing grease composition of the present invention preferably comprises 70 to 95 parts by weight of component (a) of the carbonate compound, and 5 to 30 parts by weight of component (b) of the alkali metal salt and/or alkaline earth metal salt.
- If the amount of component (b) of the alkali metal salt and/or alkaline earth metal salt is less than 5 parts by weight, a worked penetration becomes soft, and as a result, the grease composition leaks or scatters during revolution of a bearing, resulting in possibility of contaminating HDD, FDD and the like.
- On the other hand, if the above amount of component (b) exceeds 30 parts by weight, the grease composition becomes too hard, and flowability of grease in the bearing becomes poor. As a result, there is the possibility of causing defective lubrication.
- The bearing grease composition according to the present invention can contain, in addition to the components (a) and (b) described above, lubricants other than the component (a), and various additives, as a third component.
- Examples of the lubricants used in the present invention include mineral oils, synthesized hydrocarbon oils, ether oils and ester oils, which are generally used as a base oil of grease compositions.
- The additives used in the present invention are additives generally used in grease composition, and the examples thereof include antioxidants and rust inhibitors.
- The grease composition of the present invention may further contain one or more of thickening agents.
- The present invention described in detail below.
- (1) According to the preferred embodiments of the present invention, a bearing grease composition preferably comprises:
-
- wherein R and R′ which may be the same or different each represent a branched alkyl group having 13 to 15 carbon atoms; and
- (b) a group consisting of an alkali metal salt and/or an alkaline earth metal salt, synthesized from a hydroxide of an alkali metal or an alkaline earth metal and a higher hydroxyfatty acid having 10 or more carbon atoms or a higher hydroxyfatty acid having at least one hydroxyl group and having 10 or more carbon atoms.
- (2) Preferably, the bearing grease composition comprises:
-
-
- wherein n is a number of 13 to 15 and m is a number of 0 to 6; and
- (b) a group consisting of an alkali metal salt and/or an alkaline earth metal salt, synthesized from a hydroxide of an alkali metal or an alkaline earth metal and a higher hydroxyfatty acid having 10 or more carbon atoms or a higher hydroxyfatty acid having at least one hydroxyl group and having 10 or more carbon atoms.
- (3) The bearing grease composition comprises 70 to 95 parts by weight of the carbonate compound represented by formulas (I) and (II) and 5 to 30 parts by weight of the member selected from the group consisting of an alkali metal salt and/or an alkaline earth metal salt, synthesized from a hydroxide of an alkali metal or an alkaline earth metal and a higher hydroxyfatty acid having 10 or more carbon atoms or a higher hydroxyfatty acid having at least one hydroxyl group and having 10 or more carbon atoms.
- (4) The bearing grease composition for hard disc drive includes preferably a plurality of carbonate compounds.
- (5) The bearing grease composition for hard disc drive in which the carbonate compound preferably has a dynamic viscosity of 10 to 50 mm2/sec at 40° C.
- (6) Preferably, the bearing grease composition further comprises one or more thickening agents.
- (7) The bearing grease composition as in any of the above-described aspects (1) to (6) comprising further lubricants and/or additives.
- The carbonate compound can be used alone or as mixtures thereof.
- The present invention will now be described in more detail below by referring to the following examples, but the invention should not be limited thereto.
- Those examples are the preparation example of the typical bearing grease composition consisting of component (a) and component (b).
-
-
-
- (this carbonate is hereinafter referred to as “carbonate oil A”) alone, or a mixed oil of a carbonate containing commercially available organic carbonate having different structure of an alkyl group (CYCRANT T-394, trade name, a product of Mitsui Petrochemical Industries, Ltd.) (this ester is hereinafter referred to as “carbonate ester oil B”) and the carbonate ester oil A was mixed with lithium stearate and/or lithium 12 hydroxystearate in the proportions as shown in Table 1 such that the sum of those was 100 mass %. The resulting mixture was heated to 220-230° C. while stirring until the whole of mixture became liquid. The liquid thus obtained was poured into a stainless steel vessel at a depth of 3-5 mm. The liquid was cooled at 50° C. or less and then homogenized with three rollers to obtain a grease composition.
- Grease compositions were obtained in the same manner as in Examples 1 to 6 above except that an alkyl diphenyl ether or a polyol ester was further used as a third component other than components (a) and (b) in the proportion as shown in Table 1.
- Two kinds of commercially available greases in which a base oil and a thickening agent are known were used for the sake of comparison. In Table 2, reference sign + means that such a compound is contained.
- Grease compositions were obtained in the same manner as in Examples 1-6 except that a base oil and a lithium soap were used in the proportions as shown in Table 2.
- The grease compositions obtained in the above Examples and Comparative Examples were measured for a worked penetration and a dropping point, and were subjected to motor characteristic test, under the same conditions. The results obtained are shown in Tables 1 and 2.
- The worked penetration was measured according to JIS K2220, 5.3, and the dropping point was measured according to JIS K2220, 5.4.
- The motor characteristic test was conducted such that a bearing having included therein a grease composition to be tested was incorporated in a spindle motor, the motor was rotated at 10,000 rpm at a normal temperature, and noise generated, amount of evaporation (scatter) and rotating torque were measured.
- Noise was measured with a microphone at a place which is 30 cm apart from a hub edge of the motor during rotation of motor.
- The amount of evaporation (scatter) was determined by the difference between weight of motor before rotation and weight of motor after rotation.
- The torque was determined by measuring electric current value at the rotation of motor with an ammeter, and the torque stability was determined by the difference between the maximum electric current value and the minimum electric current value.
- The judgement results according to performances required for a bearing grease composition for HDD or the like on each evaluation item are shown in Table 1 (Examples) and Table 2 (Comparative Examples).
- The smaller the value, the better the low noise property; the smaller the amount of evaporation (scatter), the better the low scatter property; the lower the value, the better the low torque property; and the smaller the fluctuation, the better the torque stability.
- The tests were evaluated with the following four grades.
- A: Particularly excellent
- B: Excellent
- C: Moderate
- D: Poor
TABLE 1 Example 1 2 3 4 5 6 7 8 Thickening agent StLi 25 25 10 15 20 20 12OH St-Li 15 10 5 Base oil Carbonate A 75 85 38 90 90 80 70 70 Carbonate B 37 ADE 10 POE 10 Viscosity of 18 18 50 18 18 18 25 21 base oil (40° C.) Worked 198 203 196 305 247 181 210 205 Penetration (25 ° C.) Dropping point 197 194 198 193 193 195 197 195 (° C.) Motor charac- teristic Test Low noise A A B B B A B B property Low scatter A B A B B B A A property Low torque A A B A A A B B property Torque A A B B B A A A stability Total A A B B B A B B evaluation -
TABLE 2 COMPARATIVE EXAMPLE 1 2 3 4 Thickening agent StLi + 25 25 12OH St-Li + Na-Complex + Base oil Carbonate ester A Carbonate ester B 75 Diester oil + 38 POE + 37 Mineral oil + Viscosity of base oil (40° C.) 26 145 18 130 Worked penetration 250 205 197 181 Dropping point (° C.) 194 >260 197 199 Motor characteristic test Low noise property C D D B Low scatter property B A D A Torque C B B D Torque stability D C D C Total evaluation C C D C - As shown in Table 1 above, the bearing grease composition of the present invention shows low evaporation (scatter), low noise, low torque property and stable torque.
Claims (12)
1. A grease composition for a bearing for a spindle motor comprising:
(a) a base oil including a carbonate compound represented by the following formula (I):
wherein R and R′, which may be the same or different, are each represented by the following formula (II):
wherein n is a number from 13 to 15 and m is a number from 0 to 6; and
(b) at least one of lithium stearate and lithium 12-hydroxystearate,
wherein said grease composition comprises 70 to 95 parts by weight of component (a) and 5 to 30 parts by weight of component (b).
2. The grease composition of claim 1 , wherein said component (a) includes two or more carbonate compounds, each represented by said formula (I), wherein said carbonate compounds may be the same compound or a mixture of compounds.
3. The grease composition of claim 1 , wherein said grease composition includes a lubricant and/or additives.
4. The grease composition of claim 3 , wherein said lubricant is selected from the group consisting of a mineral oil, synthesized hydrocarbon oil, ether oil and ester oil.
5. The grease composition of claim 3 , wherein said additives are an antioxidant and a rust inhibitor.
6. The grease composition of claim 1 , wherein said component (a) has a dynamic viscosity of 10 to 50 mm2/sec at 40° C.
10. The grease composition of claim 4 , wherein said lubricant is selected from alkyl diphenyl ether and polyol ester oil.
11. The grease composition of claim 1 , wherein said spindle motor is for a hard disk drive.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/207,096 US20030013622A1 (en) | 1998-08-22 | 2002-07-30 | Bearing grease composition |
US10/883,960 US20050054544A1 (en) | 1998-08-22 | 2004-07-06 | Bearing grease composition |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10-274238 | 1998-08-22 | ||
JP10274238A JP2000063874A (en) | 1998-08-22 | 1998-08-22 | Bearing grease composition for hdd etc. |
US09/349,465 US20020111279A1 (en) | 1998-08-22 | 1999-07-09 | Bearing grease composition |
US10/207,096 US20030013622A1 (en) | 1998-08-22 | 2002-07-30 | Bearing grease composition |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/349,465 Continuation US20020111279A1 (en) | 1998-08-22 | 1999-07-09 | Bearing grease composition |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/883,960 Continuation US20050054544A1 (en) | 1998-08-22 | 2004-07-06 | Bearing grease composition |
Publications (1)
Publication Number | Publication Date |
---|---|
US20030013622A1 true US20030013622A1 (en) | 2003-01-16 |
Family
ID=17538935
Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/349,465 Abandoned US20020111279A1 (en) | 1998-08-22 | 1999-07-09 | Bearing grease composition |
US10/207,096 Abandoned US20030013622A1 (en) | 1998-08-22 | 2002-07-30 | Bearing grease composition |
US10/883,960 Abandoned US20050054544A1 (en) | 1998-08-22 | 2004-07-06 | Bearing grease composition |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/349,465 Abandoned US20020111279A1 (en) | 1998-08-22 | 1999-07-09 | Bearing grease composition |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/883,960 Abandoned US20050054544A1 (en) | 1998-08-22 | 2004-07-06 | Bearing grease composition |
Country Status (4)
Country | Link |
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US (3) | US20020111279A1 (en) |
EP (1) | EP0987312B1 (en) |
JP (1) | JP2000063874A (en) |
DE (1) | DE69918007T2 (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001072989A (en) * | 1999-09-08 | 2001-03-21 | Minebea Co Ltd | Bearing for high-efficiency motor |
JP4464498B2 (en) * | 1999-09-08 | 2010-05-19 | 日本グリース株式会社 | Bearing grease composition for motor |
JP2001081492A (en) * | 1999-09-08 | 2001-03-27 | Minebea Co Ltd | Low-torque low-noise long-life bearing |
JP3978998B2 (en) * | 2000-11-14 | 2007-09-19 | 日本精工株式会社 | Rolling bearing |
JP2002265970A (en) | 2001-03-14 | 2002-09-18 | Koyo Seiko Co Ltd | Grease composition and rolling bearing lubricated with the grease composition |
KR101088193B1 (en) * | 2006-06-15 | 2011-11-30 | 니혼 덴산 가부시키가이샤 | Method of preventing lubricant from deteriorating, lubricant, and dynamic-pressure bearing device |
US7998913B2 (en) * | 2007-06-11 | 2011-08-16 | Hitachi Global Storage Technologies Netherlands B.V. | Flow modifiers for improved magnetic recording device |
CN102796589A (en) * | 2012-07-24 | 2012-11-28 | 北京金骄生物质化工有限公司 | Environment-friendly synthesized lubricant and preparation method thereof |
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US5103169A (en) * | 1989-11-15 | 1992-04-07 | Texas Instruments Incorporated | Relayless interconnections in high performance signal paths |
US5506510A (en) * | 1994-05-18 | 1996-04-09 | Genrad, Inc. | Adaptive alignment probe fixture for circuit board tester |
US6265361B1 (en) * | 1999-09-08 | 2001-07-24 | Minebea Co., Ltd. | Bearing grease composition for motor |
US6500788B2 (en) * | 1998-07-07 | 2002-12-31 | Kyodo Yushi Co., Ltd. | Lubricating grease composition |
US6539027B1 (en) * | 1999-01-19 | 2003-03-25 | Coastcom | Reconfigurable, intelligent signal multiplexer and network design and maintenance system therefor |
US6691269B2 (en) * | 2000-12-22 | 2004-02-10 | Logicvision, Inc. | Method for scan controlled sequential sampling of analog signals and circuit for use therewith |
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US2739127A (en) * | 1952-07-02 | 1956-03-20 | Exxon Research Engineering Co | Lubricating grease containing organic carbonates |
JPS6044593A (en) * | 1983-08-23 | 1985-03-09 | Idemitsu Kosan Co Ltd | General-purpose grease composition |
IT1230064B (en) * | 1989-04-18 | 1991-09-27 | Euron Spa | LUBRICANT FLUID FOR STEEL COLD ROLLING. |
IT1243858B (en) * | 1990-10-19 | 1994-06-28 | Agip Petroli | LUBRICANT COMPOSITIONS FOR AUTOTRATION. |
JP3324628B2 (en) * | 1994-11-18 | 2002-09-17 | 日本精工株式会社 | Low dusting grease composition |
JP2001072989A (en) * | 1999-09-08 | 2001-03-21 | Minebea Co Ltd | Bearing for high-efficiency motor |
-
1998
- 1998-08-22 JP JP10274238A patent/JP2000063874A/en active Pending
-
1999
- 1999-07-09 US US09/349,465 patent/US20020111279A1/en not_active Abandoned
- 1999-08-02 DE DE69918007T patent/DE69918007T2/en not_active Expired - Fee Related
- 1999-08-02 EP EP99115246A patent/EP0987312B1/en not_active Expired - Lifetime
-
2002
- 2002-07-30 US US10/207,096 patent/US20030013622A1/en not_active Abandoned
-
2004
- 2004-07-06 US US10/883,960 patent/US20050054544A1/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5103169A (en) * | 1989-11-15 | 1992-04-07 | Texas Instruments Incorporated | Relayless interconnections in high performance signal paths |
US5506510A (en) * | 1994-05-18 | 1996-04-09 | Genrad, Inc. | Adaptive alignment probe fixture for circuit board tester |
US6500788B2 (en) * | 1998-07-07 | 2002-12-31 | Kyodo Yushi Co., Ltd. | Lubricating grease composition |
US6539027B1 (en) * | 1999-01-19 | 2003-03-25 | Coastcom | Reconfigurable, intelligent signal multiplexer and network design and maintenance system therefor |
US6265361B1 (en) * | 1999-09-08 | 2001-07-24 | Minebea Co., Ltd. | Bearing grease composition for motor |
US6691269B2 (en) * | 2000-12-22 | 2004-02-10 | Logicvision, Inc. | Method for scan controlled sequential sampling of analog signals and circuit for use therewith |
Also Published As
Publication number | Publication date |
---|---|
US20020111279A1 (en) | 2002-08-15 |
EP0987312B1 (en) | 2004-06-16 |
JP2000063874A (en) | 2000-02-29 |
US20050054544A1 (en) | 2005-03-10 |
DE69918007T2 (en) | 2005-07-07 |
EP0987312A1 (en) | 2000-03-22 |
DE69918007D1 (en) | 2004-07-22 |
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