Heat resistant lithium grease composition and a small motor reduced noise bearing

Abstract

A heat-resistant noise-reduction grease and a bearing containing the grease for a small motor such as a motor for imaging equipment such as a blower fan and motor bearing for a household electrical appliance such as an air conditioner, which is eco-friendly and excellent in noise-reduction properties is provided. The heat-resistant lithium grease composition is composed of 5 to 20% by weight of a thickener and 95 to 80% by weight of a base oil, wherein long-chain fatty acid lithium soap with 26 to 32 carbon atoms and lithium soap comprising a higher fatty acid with 10 to 20 carbon atoms and/or a higher hydroxyfatty acid with one or more hydroxyl groups and 10 or more carbon atoms are used as the thickener, and the base oil contains, as a main component, polymer ester oil (A) in which 8 or more ester groups are arranged in comb tooth form on one side of chain molecules of oil constituted with 8 or more carbon atoms, which is expressed by the following general formula: (where each of R 1 , R 2 , R 3 and R 4 represents an alkyl group, x represents an integer satisfying x≧2, and y represents an integer satisfying y≧2). and the base oil has a viscosity (40° C.) of 30 to 100 mm 2 /s.

1 . A heat resistant lithium grease composition comprising:
 a) more than 5% to less than 20% by weight of a lithium soap thickener;   b) said lithium soap thickener comprising a long-chain fatty acid lithium soap with 26 to 32 carbon atoms and
 i) a higher fatty acid lithium soap with 10 to 20 carbon atoms or 
 ii) a higher hydroxyfatty acid lithium soap with one or more hydroxyl groups and 10 or more carbon atoms, or 
 iii) both i and ii; 
   c) 95 to 80% by weight of a base oil;   d) said base oil including a polymer ester oil in which 8 or more ester groups are arranged in a comb tooth form on one side of chain molecules which is expressed by Formula 1   
     
       
         
         
             
             
         
       
     
     (where each of R 1 , R 2 , R 3  and R 4  represents an alkyl group, x is an integer satisfying x≧2, and y is an integer satisfying y≧2) 
     and said base oil having a viscosity (40° C.) of 30 to 100 mm 2 /s. 
   
   
       2 . The lithium grease composition according to  claim 1  wherein the lithium soap thickener is about 7.5% to about 17.5% by wt. 
   
   
       3 . The lithium grease composition according to  claim 1  wherein the lithium soap thickener is about 10% to about 15% by wt. 
   
   
       4 . The lithium grease composition according to  claim 2  wherein the lithium soap thickener includes a montanic acid lithium soap. 
   
   
       5 . The lithium grease composition according to  claim 4  wherein the lithium soap thickener includes a montanic acid lithium soap as a substantial component. 
   
   
       6 . The lithium grease composition according to  claim 1  wherein said long-chain fatty acid lithium soap with 26 to 32 carbon atoms is present in an amount of 0.1 to 10.0% by weight of the total of the grease composition. 
   
   
       7 . The lithium grease composition according to  claim 1  wherein said thickener includes 12-hydroxystearic acid lithium soap lithium soap in an amount of 1.5 to 10.5% by weight of the total of the grease composition 
   
   
       8 . The lithium grease composition according to  claim 1  wherein said straight-chain fatty acid lithium soap with 10 to 20 carbon atoms in an amount of 0.5 to 5.0% by weight of the total of the grease composition. 
   
   
       9 . The lithium grease composition according to  claim 1  further comprising said base oil includes a synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil or mineral oil. 
   
   
       10 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil and mineral oil. 
   
   
       11 . The lithium grease composition according to  claim 1  further comprising said base oil comprising a synthetic hydrocarbon oil. 
   
   
       12 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic hydrocarbon oil, and a mineral oil. 
   
   
       13 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic hydrocarbon oil and a synthetic ester oil. 
   
   
       14 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic hydrocarbon oil and a synthetic ether oil. 
   
   
       15 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, and a mineral oil. 
   
   
       16 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic ether oil, a synthetic hydrocarbon oil, and a mineral oil. 
   
   
       17 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, and a synthetic ether oil. 
   
   
       18 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil and mineral oil. 
   
   
       19 . The lithium grease composition according to  claim 1  further comprising said base oil including a mineral oil. 
   
   
       20 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic ester oil and a mineral oil. 
   
   
       21 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic ether oil and a mineral oil. 
   
   
       22 . The lithium grease composition according to  claim 1  further comprising said base oil including a synthetic ester oil, a synthetic ether oil and mineral oil. 
   
   
       23 . The lithium grease composition according to  claim 1  wherein said polymer ester oil in an amount of 20% to 50% by weight of the total of the grease composition, said base oil including a synthetic hydrocarbon oil in an amount of 10% to 40% by weight of the total of the grease composition, and a mineral oil in an amount of 10 to 40% by weight of the total grease composition. 
   
   
       24 . The lithium grease composition according to  claim 1  further comprising said polymer ester oil in an amount of 20% to 50% by weight of the total of the grease composition, said base oil including a synthetic ester oil in an amount of 10% to 40% by weight of the total of the grease composition, and a synthetic hydrocarbon oil in an amount of 10 to 40% by weight of the total of the grease composition. 
   
   
       25 . The lithium grease composition according to  claim 1  further comprising said polymer ester oil in an amount of 20% to 50% by weight of the total of the grease composition, said base oil including a synthetic ester oil in an amount of 10% to 30% by weight of the total of the grease composition, a synthetic hydrocarbon oil in an amount of 2 to 10% by weight of the total of the grease composition, and a synthetic ether in an amount of 10% to 30% by weight of the total of the grease composition. 
   
   
       26 . The lithium grease composition according to  claim 1  further comprising said grease composition includes an antioxidant or an anticorrosive agent or both an antioxidant and an anticorrosive agent. 
   
   
       27 . The lithium grease composition according to any one of  claim 9  further comprising said grease composition includes an antioxidant or an anticorrosive agent or both an antioxidant and an anticorrosive agent. 
   
   
       28 . The lithium grease composition sealed according to  claim 1  wherein said polymer ester oil is present in an amount of 20% to 50% by weight of said grease composition. 
   
   
       29 . The lithium grease composition according to  claim 1  wherein said polymer ester oil is present in a significant amount of 20% or greater by weight of said base oil. 
   
   
       30 . The lithium grease composition according to  claim 1  wherein said polymer ester oil has a molecular weight of 1000 to 3000 and a viscosity (40° C.) of 100 to 1000 mm 2 /s. 
   
   
       31 . The lithium grease composition according to  claim 9  wherein in d said polymer ester oil has a molecular weight of 1000 to 3000 and a viscosity (40° C.) of 100 to 1000 mm 2 /s. 
   
   
       32 . The lithium grease composition according to  claim 9  wherein said synthetic ester oil is
 a) a synthetic diester oil having the formula:
   RCOOH(CH 2 ) n COOR′ 
   (where R and R′ represent alkyl groups with 3 to 18 carbon atoms, and can be identical or different from each other, and n is 3 to 12.);   b) a synthetic trimester oil having the formula
   R(CH 2 COOR′) 3    
   (where R and R′ represent alkyl groups with 3 to 10 carbon atoms);   c) a synthetic tetraester oil having the formula
   R(CH 2 COOR′) 4    
   (where R and R′ represent alkyl groups with 3 to 10 carbon atoms); or   d) a synthetic neopentyl polyol ester oil.   
   
   
       33 . The lithium grease composition according to  claim 9  wherein said synthetic hydrocarbon oil is a poly-α-olefin oil or a polybutene and olefin copolymer, that has a viscosity (40° C.) of 20 to 100 mm 2 /s. 
   
   
       34 . The lithium grease composition according to  claim 9  wherein said synthetic ether oil is an alkyl diphenyl ether. 
   
   
       35 . The lithium grease composition according to  claim 3   claim 1  wherein said synthetic ether oil is dialkyl diphenyl ether, monoalkyl diphenyl ether, or a mixture thereof. 
   
   
       36 . The lithium grease composition according to  claim 9  wherein said mineral oil is a paraffinic oil with a viscosity (40° C.) of 90 to 150 mm 2 /s. 
   
   
       37 . A low noise small motor bearing comprising:
 a bearing;   a heat resistant lithium grease composition sealed in said bearing;   said heat resistant lithium grease composition comprising:   a) more than 5% to less than 20% by weight of a lithium soap thickener;   b) said lithium soap thickener comprising a long-chain fatty acid lithium soap with 26 to 32 carbon atoms and
 i) a higher fatty acid lithium soap with 10 to 20 carbon atoms, or 
 ii) a higher hydroxyfatty acid lithium soap with one or more hydroxyl groups and 10 or more carbon atoms, or 
 iii) both i and ii; 
   c) 95 to 80% by weight of a base oil;   d) said base oil including a polymer ester oil in which 8 or more ester groups are arranged in a comb tooth form on one side of chain molecules which is expressed by Formula 1   
     
       
         
         
             
             
         
       
     
     (where each of R 1 , R 2 , R 3  and R 4  represents an alkyl group, x is an integer satisfying x≧2, and y is an integer satisfying y≧2) 
     and said base oil having a viscosity (40° C.) of 30 to 100 mm 2 /s. 
   
   
       38 . A low noise small motor bearing according to  claim 37  wherein the lithium soap thickener is about 7.5% to about 17.5% by wt. 
   
   
       39 . A low noise small motor bearing according to  claim 37  wherein the lithium soap thickener is about 10% to about 15% by wt. 
   
   
       40 . A low noise small motor bearing according to  claim 38  where in the lithium soap thickener includes a montanic acid lithium soap. 
   
   
       41 . A low noise small motor bearing according to  claim 40  where in the lithium soap thickener includes a montanic acid lithium soap in an substantial amount. 
   
   
       42 . A low noise small motor bearing according to  claim 37  wherein said long-chain fatty acid lithium soap with 26 to 32 carbon atoms is present in an amount of 0.1 to 10.0% by weight of the total of the grease composition. 
   
   
       43 . A low noise small motor bearing according to  claim 37  wherein said thickener includes 12-hydroxystearic acid lithium soap in an amount of 105 to 10.5% by weight of the total of the grease composition. 
   
   
       44 . A low noise small motor bearing according to  claim 37  wherein said straight-chain fatty acid lithium soap with 10 to 20 carbon atoms is present in an amount of 0.5 to 5.0 by weight of the total of the total grease composition. 
   
   
       45 . A low noise small motor bearing according to  claim 37  further comprising said base oil including synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil or mineral oil. 
   
   
       46 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil and mineral oil. 
   
   
       47 . A low noise small motor bearing according to  claim 37  further comprising said base oil comprising a synthetic hydrocarbon oil. 
   
   
       48 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic hydrocarbon oil and a mineral oil. 
   
   
       49 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic hydrocarbon oil and a synthetic ester oil. 
   
   
       50 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic hydrocarbon oil and a synthetic ether oil. 
   
   
       51 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, and a mineral oil. 
   
   
       52 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic ether oil, a synthetic hydrocarbon oil, and a mineral oil. 
   
   
       53 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, and a synthetic ether oil. 
   
   
       54 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, synthetic ether oil and mineral oil. 
   
   
       55 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a mineral oil. 
   
   
       56 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic ester oil and mineral oil. 
   
   
       57 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic ether oil and mineral oil. 
   
   
       58 . A low noise small motor bearing according to  claim 37  further comprising said base oil including a synthetic ester oil, a synthetic ether oil and mineral oil. 
   
   
       59 . A low noise small motor bearing according to  claim 37  wherein said polymer ester oil in an amount of 20 to 50% by weight of the total of the grease composition, said base oil including a synthetic hydrocarbon oil in an amount of 10 to 40% by weight of the total of the grease composition, and a mineral oil in an amount of 10 to 40% by weight of the total grease composition. 
   
   
       60 . A low noise small motor bearing according to claim further comprising said polymer ester oil in an amount of 20 to 50% by weight of the total of the grease composition, said base oil including a synthetic ester oil in an amount of 10 to 40% by weight of the total of the grease composition, and a synthetic hydrocarbon oil in an amount of 10 to 40% by weight of the total of the grease composition. 
   
   
       61 . A low noise small motor bearing according to  claim 37  further comprising said polymer ester oil in an amount of 20 to 50% by weight of the total of the grease composition, said base oil including a synthetic ester oil in an amount of 10 to 30% by weight of the total of the grease composition, a synthetic hydrocarbon oil in an amount of 2 to 10% by weight of the total of the grease composition, and a synthetic ether in an amount of 10 to 30% by weight of the total of the grease composition. 
   
   
       62 . A low noise small motor bearing according to  claim 37  further comprising said grease composition includes an antioxidant or an anticorrosive agent or both an antioxidant and an anticorrosive agent. 
   
   
       63 . A low noise small motor bearing according to  claim 45  further comprising said grease composition includes an antioxidant or an anticorrosive agent or both and antioxidant and an anticorrosive agent. 
   
   
       64 . A low noise small motor bearing according to  claim 37  wherein said polymer ester oil is present in an amount of 20 to 50% by weight of said grease composition. 
   
   
       65 . A low noise small motor bearing according to  claim 37  wherein said polymer ester oil is present in a significant amount 20% or greater by weight of said base oil. 
   
   
       66 . A low noise small motor bearing according to  claim 37  wherein said polymer ester oil has a molecular weight of 1,000 to 3,000 and a viscosity (40°) of 100 to 1,000 mm 2 /s. 
   
   
       67 . A low noise small motor bearing according to  claim 45  wherein said polymer ester oil has a molecular weight of 1,000 to 3,000 and a viscosity (40°) of 100 to 1,000 mm 2 /s. 
   
   
       68 . A low noise small motor bearing according to  claim 45  wherein said synthetic ester oil is
 a) a synthetic diester oil having the formula:
   RCOOH(CH 2 ) n COOR′ 
   (where R and R′ represent alkyl groups with 3 to 18 carbon atoms, and can be identical or different from each other, and n is 3 to 12.);   b) a synthetic trimester oil having the formula
   R(CH 2 COOR′) 3    
   (where R and R′ represent alkyl groups with 3 to 10 carbon atoms);   c) a synthetic tetraester oil having the formula
   R(CH 2 COOR′) 4    
   (where R and R′ represent alkyl groups with 3 to 10 carbon atoms); or   d) a synthetic neopentyl polyol ester oil.   
   
   
       69 . A low noise small motor bearing according to  claim 45  wherein said synthetic hydrocarbon oil is a poly-α-olefin oil or a polybutene and olefin copolymer, that has a viscosity (40° C.) of 20 to 100 mm 2 /s. 
   
   
       70 . A low noise small motor bearing according to  claim 45  wherein said synthetic ether oil is an alkyl diphenyl ether. 
   
   
       71 . A low noise small motor bearing according to  claim 70  wherein said synthetic ether oil is dialkyl diphenyl ether, monoalkyl diphenyl ether, or a mixture thereof. 
   
   
       72 . A low noise small motor bearing according to  claim 45  wherein said mineral oil is a paraffinic oil with a viscosity (40° C.) of 90 to 150 mm 2 /s. 
   
   
       73 . An air conditioner comprising a motor; said motor having one or more bearing according to  claim 37 . 
   
   
       74 . A blower for image equipment comprising;
 a) motor;   b) said motor having one or more bearings made according to  claim 37 .