CA1197231A - High dropping-point lithium-complex grease composition - Google Patents

Abstract

A B S T R A C T

HIGH DROPPING-POINT LITHIUM COMPLEX
GREASE COMPOSITION

High dropping-point lithium-complex grease composition having improved anti-noise properties, comprising a lubricating oil and the following components a) at least one lithium soap selected from the group consisting of the lithium salts of C10 to C34 fatty acids and C12 to C24 hydroxy fatty acids, b) a lithium salt of aromatic hydroxy carboxylic acid, and c) a succinimide-type dispersant and/or metal salt detergent.

Description

3~
HIGH DRDPPING Por~r LITHIUM COMPLEX GRE~SE CQMPOSITION

me Eresent invention relates to a high-quality lithium-~mrl~ grease c~mposition having a high dropping point, e~ n~.
oxidation stAbility, long lubxication life and very satisfactory acoustic characteristic.
Lithium-soap greases are conventionally used widely for their various merits, such as the fairly satisfactory thermal and water resistance, easy dispersio.n in many types of lubricant base materials c~nd the r~ n~hle prices. ~lowever, when this type of grease is used at a temperature higher than 130C, -the lubricating r~ rn~ "~,ln~e o the grease is rapidly lowered due to the micelle destruction by oxidative deterioration, reduction of adhesivity, softening and oil separation.
Whi.le rnn~ r-base greases of very high dropping points and other various complex greases are developed for eliminating the these thermal defec-ts, the thickeners of these greases can be h~rde~1 or severely softened during their long use, and thus the arrl;~ation of such greases is naturally limited also for their high prices. On the other hand, the use envirorlment oE greases is being rapidly agyLc~vclted with the advancing miniaturization of .h;n~c and speeding up of working parts. For instance, when grease is used in a place near the heat source of an engine, such as in a bearing for el.ectr.ic ff~l; r ent~ the grease is exposed to a very high t~mperature for a long time, and, 1~7Z3~

therefore, has to be sufficiently durable to high tempera-ture, long use and ambient moisture. Under such circumstance, strong request.s are being made for the development of a novel grease far more excellent in these characteristics than the existent lithium-~oap. greases.
The purpose of the present invention is to answer these requests by providing a high-quality lithium complex .grease having a high dropping point, satisfactory adhesivity and high thermal stability of the thickener micelles, all of which are essential under the use condition higher than 130C, and this purpose can be achieved with a lithium complex grease prepared by adm;~; ng and dispersing in a base oil, a lithium salt of a fatty acid and/or hydroxy fatty acid, that of aromatic hydroxyl carboxylic acid and a succinimide-type dispersant and/or metallic-salt detergent, as essential components.
It is disclosed in Canadian Patent 1,005,428, issued February 15, 1977, that a high dr~pping point lithium-soap grease caul be prepared by ar~mi~; ng in a lithium soap of a hydroxy fatty acid, a dilithium ~alt of an aliphatic dicarboxylic acid or a monolithium borate and a lithium ~alt of a hydroxyl-carboxylic acid, such as an aromatic hydroxy-carboxylic acid, as essential cornponents. However, a grease of a sufficiently high dropping point cannot be formed only from the two 2S components comprising a lithium salt of a hydroxy fatty acid and a dilithium salt of an aromatic hydroxy carboxylic acid.

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In the pre~ent invention, it ha~ been discovered that an exceedingly high~quality and high-dropping point lithium complex grease can be prepared by incorporating a ~uccinimide-type dispersant and/or metallic-salt detergent, as a third component, in addition to the two components mentioned above.
That is, the present invention provides a high-dropping-point lithium-complex grea~e composition prepared by unlformly a~ i ng an~ dispersing, in a base oil having a lubricating viscosity, the following three essential component~ ;
(a) at least one lithium ~alt selected from the lithium salts of ClO to C34 fatty acids and Cl2 to C24 hydroxy fatty acids, (b) a lithium ~alt of an aromatic hydroxycarboxylic acid, and (c) a succinimide-type dispersant and/or metallic-salt detergent.
In the following, a fur~her detailed descript~on i8 made on the lithium~complex grease composition provid0d according to the present invention.

Ba6e oil :
r~he base oil used in the composition accordlng to the pre~ent inventlon i6 a mineral or synthetic hydrocarbon oil, 6ynthetic ester or similar oil or a mlxture thereof, which are conventionally employed as lubricating oils. The vi6co~1ty of thi6 base oil can be generally within the range from about

2 to 500 cSt at 40C, preferably from about 20 to 200 cSt at L~OC.

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,~gt~

As the synthetic oil, use can be made, for example, o~ a poly-~-olefine oligomer, such a6 an octene-l/decsne-1 copolymer having a viscosity of 41~0 cSt at 40C, V.I. of 130; pour point of -60C and flash point of 223C ; a dicarboxylic acid ester, such as di-2-ethylhexyl sebacate ;
and a hindered-ester oil, such a6 caprylic ester of trimethylolpropane and caproic ester of pentaerythritol.
Moreover, various other synthetic oils, such as polyglycol oil, 6ilicone oil, polyphenylether oil, halogenated hydro-carbon oil and alkylbenzene oil~ can also be used.

Component (a) :
The lithium soap to be admixed in the base oil accord-ing to the present invention is selected from the lithium salts of C10 to C34 fatty acids and those of C12 to C24 hydroxyfatty a.cids. The C10 to C34 fatty acids employed for the formation o~ such lithium salts include saturated or un~aturated higher ~atty acids, such as capric acld, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid, lignoceric a.cid, 2Q cerotic acid, montanic acid, melis6ic acid, aleic a.cid, elaidic acid~ erucic acid, ~oomaric acid, gadoleic acid, linolic acld and linolen~c acid, and the glycerides o~ these acids. Among these acids and glycerides, those cont~ining 16 to 22 carbon atoms are preferable and especially ap-propriate are palmiti.c acid, stearic acid and elaidic acid.

- ~97~33L

The C12 to C24 h~droxy fatty acids are normally those straight-chained saturated or unsaturated aliphatic mono-carboxylic acids containing a hydroxyl radical in their respective molecules, for example, ricinolic acid, 2-hydroxy dodecanoic acid, 2-hydroxy tetradecanoic acid, 2-hydroxy hexadecanoic acid, ll-hydroxy hexadecanoic acid, ambrettolic acid, ricinole~cacid, ricinostearolic acid, 9-hydroxy stearic acid, lO-hydroxy stearic acid and 12-hydroxy stearic acid, and, among these acids, those contein~ng 18 carbon atoms and a hydroxyl radical connected to the 9-, lO- or 12-position, especially 12-hydroxy stearic acid and ricinoleic acid are preferable.
The lithium salts of the higher fatty acids above or those of hydroxy fatty acids can be used singly or combinedly with one or more of others. ~urthermore, when lithium salts are prepared from these fatty acids or hydroxyfatty acids, these acids can be reacted with lithium hydroxide, in the ~orm of their. free acids as well as of their glycerides.

Component (b) :
The second component to be admixed in the ba6e oil ac~-cording to the present invention is a lithium salt of an aromatic hydroxy carboxylic acid. The aromatic hydroxyl carboxylic acid used should desirably be represented by the formula, o O OH
~}~
R

~ ~, 9 -7r,~

(wherein R denotes a hydrogen atom or hydroxyl, lower alkyl or lower alkoxyl radical), and there are included in this category those acids such as p hydroxy benzoic acid, salicylic acid ~o-hydroxy benzoic acid), 2-hydroxy-4-hexyl benzoic acid, m-hydroxy benzoic acid, 2,5-dihydroxyl benzoic acid (gentisic acid), 2,6-dihydroxyl benzoic acid ( r-resorcylic acid) and 4-hydroxy-

3-methoxy benzoic acid. Salicylic acid is especially preferable among them. Incidentally, the hydroxyl radical (OH) in sald lithium salt can be present in its ~ree kype as well as in the form of -OLi.

Component (c) :
The third component to be compounded in.the base oil according to the present invention is employed for accelerat~
ing the fine dispersion of the components (a) and (b) in the base oil, and a succinimide-type disper~ant and metallic-s~lt detergent are used respectively singly or combinedly with one or more of others.
2Q The succinimide-type dispersant usable a~ Component (c) in the present inventi.on can be those ones synthesized by the reaction of polyamine and polybutenyl succinic anhydride (obtained by the reaction of polybutene and maleic anhydride) among the additives effeckively dispersing engine-oil sludge in the engine oil, and there are included in khis category the compounds represented respectively by the following ~ormulae, A -CH~
N~ -C~l ~N~ H (I) CH2 C ~ 2 2 p Al CH C~ ,~C-CH-A
~ ~C~2-~ ~2-N~ CE~2~ H? `C-CH2 c~2-c~
t II) Ai-CH-C~ ~"-CH-A
CB -C ~ 2~ H2 lI2 1~}~; CH2cH2 N~C C~

O' `O

HO ` O ' CH
( III) Al_C~_C.~ ~C~ -C~
N-C~2-CH2-N '` NH
~C~2-C~ , CH2 CH2 (IV) l O
A -CH-C ~;
C~l -C ~ ~ ~2 C~2 N~;
i~ "O 0~
o~ b B
HO' ~0' ~ 0~1 '(V) Al-C~i-C ~ CH
CH -C ~ H2 CH2 N~ CH2-CH2-N ~ 3 (Vl) ~L~9~;~3~

(wherein Al denotes a C~O to C200 polyisobutenyl rad~cal, p mean6 an integer from 2 to 8 and q repre6ents an integer from l to 8) The metallic salt detergent usable as Component (c) means those organometallic compounds capable of preventing or suppressing the deposition of the deteriorated matter in an engine to keep the engine interior clean, and includes those sulphonates, phenates, phosphonates and salicylates represented respectively by the formulae shown below.
(i) Sulphonate.
I'' ' "
A~ A2 ( ~r - ~o3 ~ ~Ar - ~a~
,~,2.t ~ ~,2~

(wherein A2 and A2 denote respectively a hydrogen atom or C8 to C30 alkyl radical, Ar means a benzene rlng or naphthalene ring, M represents an alkaline earth metal, such as Ca, Ba or Mg, and M denote6 an ~lk~li metal, such as Na, K or Li) (ii) Phenate.
O~ O
' l 1 A~ ~ ~s ~

(wherein A3 denotes a C4 to Cl6 alkyl radical, M means an ~lk~line earth metal, such as Ca, Ba or Mg, and x denotes an integer, l or 2) ~7~3~

g (iii) Pho~phonate.
O O
Il 11 A~ - P - O - ~ ~ - P - 8 -L oJ ~ L oJ

o o Il 11 _ p _ o ~ ~ A 4 --P ~ B --P
L o J , L ,~ ~
(wherein A4 means a C30 to C200 polyisobutenyl radical and M denotes an alk~ e earth metal, such as Ca, Ba or Mg) (iv) Salicylate.

( A~ ~ Coo (wherein A5 denotes a C8 to C2~ alkyl radical and M
means an ~lk~11ne earth metal, such a~ Ca, Ba or Mg) Among these metallic-salt detergents9 calcium ~ulphonate, calcium phenate, calcium salicylate and magnesium salicylate lQ are particularly preferable.

Preparation of grease composition :
The grease composition of the present invention can be prepared by uniformly a~ ing and finely dispersing the three components, (a), (b) and (c), in the base oil mentioned above.
The ~m; ~i ng proportions of these three components are not 3~1 necessarily precise but can be variable according to the types of individual components1 and it is generally advan-tageous to compound these components in the following proportions per lO0 weight parts of the base oil ;
Component(a) - 2 to 40 weight parts, preferably 5 to 20 ~eight parts, Component(b) - 0.05 to 20 weight parts, preferably 0.1 to 20 weight parts, Component(c) - 0.01 to 10 weight parts, preferably 0.1 to 5 weight parts.
Furthermore, the component~ (a) and (b) should desirably be used in the following mol ratio within the respective ranges of the proportions specified above ;
Component(a)/Component(b) mol ratio = 005 to l.0, preferably l to 5.
The composition according to the present invention can al~o be prepared from the above three component~ (a), (b) and (c) together with those optional lubricant additives con ventionally ~mployed, such a8 an oxidation inhibitor (e.g.
2,6-ditertiarybutyl-4-methyl-phenol, N-phenyl- d naphthyl-amine and diphenylamine octylate), rust inhibitor (e.g.
oxygenated para~fin, amino-imidazoline and barium dinonyl-naphthalene-sulphonate) and extrem-pressure additive (e.g.
zinc naphthenate, lead naphthenate, sulphurized oils and fats, and tricresyl phosphate). In the following, a de-scription is made on a general process for the preparation '7~3~

of the grea~e composition accvrding to the pre~ent invention.
Firstly, a component (c) i~ di6solved in the base oil at 70 to 80C, followed by the fatty acid or hydroxyl fatty acid for the formation of a component (a3. Then, the lithium hydroxide in a roughly equivalent amount to said fatty or hydroxyfatty acid i8 admlxed in the mlxture at 80 to 90C to form a soap. After the resulting solution is somewhat cooled, the aromatic hydroxyl carboxylic acid for the formation of a component (b) is admixed in the solution at 70 to 80C, the resulting mixture is gradually heated again to 80 to 90C and the lithium hydroxyde in an amount roughly equivalent to that of the aromatic hydroxy-carboxylic acid above is admixed in the mixture. The final mixture is further heated to 145 to 150C under pressure ~or dehydration. A~ter the dehydration, the mixture is again heated up to 195 to 220C, then cooled to 175 to 193C, kept at this temperature ~or 10 to 40 min and finally cooled to the room temperature for the completion of the preparation.
The lithium-complex greas~ compo6ition thus provided by the present invention has an exceedingly high dropping point and satisfactory acoustic ch~racteristic together with a long lubrication li~e, as a high-per~ormance grease, and can be suitably used for the lubrication of the bearing6 for electric motors and of the wheel bearings for automotive compact axle boxesO In addition, because of the excellent ~ y ~-,3~
\

acoustic characteristic, the present grease compo~ition can be satisfactorily used in the bearings of` air-conditioners etc, making little noise and confortable surroundings.
The present invention is further concretely illustrated by mean~ of examples as follows~

Example 1 23521.2 g o~ a refined mineral oil (paraffinic~ VI : 102, pour point : -15C, kinO viscosity : 44.9 cSt at 37~8C~
6.4 cSt at 98.9C~ 9 30 g of a succinimide (A) (ref. Note 1) and 270 g of 12-hydroxy stearic acid were introduced into a 5 liter autoclave and the contents were heated to 80C under stirring in 30 to 40 min to completely di~solve the hydroxy-stearic acid. (Note 1) Succinimide (A) Al CH C" ~` C-CU-A
CH -N}3~ CH -C~2-N
CH-;~ C-CH2 ` O OH O~' O' `O
~ B
~ O ~ ~

~Al : C52 to C76 polyisobutenyl radical, mean molecular weight : 2,302 (as contalnlng boron), 110 wt~ parts of the compound above dissolved ln 100 wt. parts of the base oil~
Sub~equently, 300 g o~ a hot aqueou~ solution (95C) cont~l ni ng 38.5 g of lithium hydroxide were admixed in the autoclave contents, which were then kept at 90C under stirring ~723 for 5 to 15 min. After the contents were cooled to 75QCf 300 g of a hot aqueous solution (93C) contairling 49.8 g of salicylic acid were admixed in the contents and dissolved by stirring for 10 to 15 min. Then, 250 g of a hot aqueous solution .(95C) containing 31.0 of lithium hydroxide were admixed in the resulting mixture, which wa~ then gradually heated under stirring and pressure. When this mixture arrived at 145 to 150C after 1 to 1.5 hrs, the autoclave was released of the pressure and the contents were dehydrated at this temperature in 15 to 25 min, After the dehydration, the contents of the autoclave were further heated to 195 to 205C, then cooled to 188 to 192C under stirring.and, after being kept at thie temperature for 20 to 30 min, further cooled to about 160Co At:this temperature; 60 6 of an oxidation inhibitor were admixed in the contents, the mixture thus obtained was cooled by stirring to about 80 to 85C in 30 to 60 min and then treated in a homogenizer. at this temperature.
The properties of the grea6e composition thu~ prepared were as follows ;
Consistency 1 (unworked) : 239 " (after 60 strokes) : 236 Shell roll test 2 (100C x 5 hrs) (before test) : 119 (a~ter test) : 149 (difference) : ~30 ~3L9~7~3 Dropping point 1 (C) : 280 Oil separation 1 (100C x 24 hr~ 2.2 %
Waker resistarlce 1 (3&~C x 1 hr) : 2.0 %
Copper-plate corrosion 1 (100C x 24 hrs) : pass Grease d~st-noise test 3 (after 120 sec3 : 68 (mean of 5 measurements) Functional life 4 : 2540 hrs ( Note *1 : according to JIS K2220, ~2 : roll stability test according to ASTM D1831, *3 : according to the method described in Japanese Patent Publication No. 2357/78, published January 27, 1978.
*4 : according to ASTM D1741 Comparison Example 1 A grease composition was prepared in a similar manner to that in Example 1 except that 2,531.2 g of the re~ined mineral oil were employed without the.succinimlde(~) being admixed. The properties of the resulting comp~sition were as follows ;
Consistency (unworked) : 278 (after 60 strokes) : 266 Shell roll test (100C x 5 hrs) (before test) : 139 (after test) : 173 (difference) : +34 7~

Dropping point (C) : 195 Grease dust noise test (after 120 sec) : 4,11~ (mean of 5 measurements ) Functional life : 1,240 hrs Examples 2 to 8, Comparison Examples 2 and 3 Seven grease compositions were prepared by treating the various components shown in Table 1 below in similar ways to that in Example 1 and the properties thereof are collectively tabularized in Table 1. Also, the properties of a market grease comprising the lithium soap of 12-hydroxystearic acid are shown as Comparison Example 2 in the table as well, In addition, Comparison Example 3 in the table is a grease prepared in a similar manner to that in Example 1 but by employing an increased amount of the refined mineral oil 15 : without the components (b) and (c) being admixed.

Table 1 ~ Compo6ition/Example Composition (~eight %) Component/Property ~ 2 3 4 _ 5 6 7 8 c_zc ~ C-3 ~) 12-hydroxy stearic acid 9.0 9.0 9.0 9.0 9.0 9 o 9 o 9 0 (b) Salicylic acid 1.66 1.66 1.66 1.66 1.66 1.66 1.66 Market (c) Succinimide (B),(l) 1.0 grease Succinimide (C),(2) 1.0 Succinimide (D),(3) 1.0 Celcium fiUl phonate, ~4) 1.O
~5agnesium salicylate, (5) 1.0 .5 Czlcium 6slicylate, (6) . _ 1 .0 Lithium bydroxyde monohydrate 2.30 2.30 Z.30 2.30 2.30 Z.30 2.30 1.29 Oxidation inhibitor, (7) 2.0 2.0 2.0 2.0 2.0 2.0 Z.O 2.0 Base oil (refined mineral oil),(c) o4.04 84.04 84.04 84.04 84.04 84.04 o4.04 87.71 Properties :
Consi~tency (un~orked) 221 218 255 242 229 258 241 272 234 " (after 60 stroke6) 222 214 248 240 226 251 239 273 232 Shell roll te6t,~(before te6t) 110 lOo 128 121 114 130 121 137 117 (100C x 5 hrs) (after te6t) 138 129 157 154 151 163 160 168 165 difference) l28 +21 +29 +33 ~37 +33 +39 +31 '48 Dropping ooint (C)~280 >280 >280~280 ~Z80 ~260 ~280 180 200 Grease dust-noi6e test (sf~er 120 6ec) 48 102 80 66 121 65 93 5 140 Eunctional life (hr) 3020 18602540 _ 2660 1780 2480 2800 500 480 g7;~3~L

(Note for l'able 1) CH~ ' `'C-CB-A
2- CE2-b~3 C~2 CH2 ~ C-CH2 L~l C52 to C76 polyisobutenyl radical, Mean molecular weight : 2,17~
110 weight parts of the above compound dissolved in 100 wei~ht parts of a refined mineral oil.

(2) -CH-C ~
CH~C ~ ~CH2 CE~2 N~ CH2-CH~'-NH2 ~0 l : C52 to C76 polyisobutenyl radical, Mean molecular weight : 1,172~
160 weight parts of the compound above dissolved in 100 weight parts of a refined mineral oil.

~3) Al-C~-C"
c~-c~ 2 ~2 M~3C~2-C~2-N~
~O 0 B
O' `o B B
~6 0~ _r~ ~
LA1 C52 to C76 polyisobutenyl radical, Mean molecular weight : 1304~
140 weight parts of the compound above dissolved in lOG
weight part~ of a refined mineral oil.

~A.

-- 1 8 ~

(4) Calcium dinonylnaphthalene-sulphate .. _ . . . ... . .. .

~C~ ~ ) 2C a 0 ~, 39 weight part~ of the compound above dissolved in 100 weight parts of a refined mineral oil.

(5) Magnesium alkyl-salicylate . . . . .. .. .. . . .
~ ~ O EI J ~ , IR C10 to C16 alkyl radica~
30 weight parts of the compound above d1s olved i~ 100 weight parts of a refined mineral oil.

(6) Calcium alkyl-sa.licylate ~R C10 to C16 alkyl radica~
lQ 30 weight parts of the compound dis~olved in 100 weight part~ of a refined mineral oil.

(7) rr'he same as that u~ed in Example 1.;

(8) r~he same as that used in Example 1.

Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. High dropping-point lithium-complex grease composition having improved anti-noise properties, comprising a lubricating oil and the following com-ponents:
a) at least one lithium soap selected from the group consisting of the lithium salts of C10 to C34 fatty acids and C12 to C24 hydroxy fatty acids, b) a lithium salt of an aromatic hydroxy carboxylic acid, and c) at least one component selected from the group consisting of succinimide-type dispersants and metal salt detergents.

2. A composition as claimed in claim 1, wherein component (b) is lithium salicylate.

3. A composition as claimed in claim 1, wherein component (c) is a succinimide.

4. A composition as claimed in claim 2, wherein component (c) is a succinimide.

5. A composition as claimed in claim 1, wherein component (c) is selected from the group consisting of calcium sulphonate, calcium salicylate and magnesium salicylate.

6. A composition as claimed in claim 2, wherein component (c) is selected from the group consisting of calcium sulphonate, calcium salicylate and magnesium salicylate.

7. A composition as claimed in claim 1, 2 or 3, wherein the proportions per 100 pbw of base oil are:
component (a) : 2-40 pbw;
component (b) : 0.05-20 pbw;
component (c) : 0.01-10 pbw.

8. A composition as claimed in claim 4, 5 or 6, wherein the proportions per 100 pbw of base oil are:
component (a) : 2-40 pbw;
component (b) : 0.05-20 pbw;
component (c) : 0.01-10 pbw.

9. A composition as claimed in claim 1, 2 or 3, wherein the mol ratio component (a)/component (b) = 0.5 to 10.

10. A composition as claimed in claim 4, 5 or 6, wherein the mol ratio component (a)/component (b) = 0.5 to 10.

11. A composition as claimed in claim 1, 2 or 3, wherein the proportions per 100 pbw of base oil are:
component (a) : 2-40 pbw;
component (b) : 0.05-20 pbw;
component (c) : 0.01-10 pbw, and the mol ratio component (a)/component (b) =
0.5 to 10.

12. A composition as claimed in claim 4, 5 or 6, wherein the proportions per 100 pbw of base oil are:
component (a) : 2-40 pbw;
component (b) : 0.05-20 pbw;
component (c) : 0.01-10 pbw, and the mol ratio component (a)/component (b) =
0.5 to 10.