Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic oxygen compound
Reexamination Certificate
1998-03-06
2001-01-16
Johnson, Jerry D. (Department: 1721)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic oxygen compound
Reexamination Certificate
active
06174844
ABSTRACT:
The present invention relates to overbased metal salts of sulphur-free calixarenes having a substituent hydroxyl group or groups available for reaction with a metal base, their preparation and their use as detergents in lubricating oil compositions.
In the operation of the internal combustion engine by-products from the combustion chamber often blow by the piston and admix with the lubricating oil.
Compounds generally employed to neutralise the acidic materials and disperse sludge within the lubricating oil are the overbased alkaline earth metal sulphurised hydrocarbyl-substituted phenates, salicylates, napthenates and sulphonates. The term “overbased” is generally used to describe those alkaline earth metal hydrocarbyl-substituted salts in which the ratio of the number of equivalents of the alkaline earth metal moiety to the number of equivalents of the acid moiety is greater than one, and is usually greater than 1.2 and may be as high as 4.5 or greater. In contrast, the equivalent ratio of alkaline earth metal moiety to acid moiety in “normal” or “neutral” alkaline earth metal hydrocarbyl-substituted salts is one, and in “low-based” salts is less than one. Thus, the overbased material usually contains greater than 20% in excess of the alkaline earth metal present in the corresponding neutral material. For this reason overbased alkaline earth metal hydrocarbyl-substituted salts have a greater capability for neutralising acidic matter than do the corresponding neutral alkaline earth metal hydrocarbyl-substituted salts, though not necessarily an increased detergency power.
In the manufacture of the aforesaid sulphurised hydrocarbyl phenates, hydrogen sulphide is generated, which hydrogen sulphide is generally disposed of by burning, thereby producing sulphur dioxide, which is released to the atmosphere. Environmental concerns are growing over the use of sulphur-containing lubricant additives, due to the resulting sulphur dioxide emissions associated with lubricant combustion in service, as well as in additive production. In response to the perceived desirability of providing sulphur-free overbased metal salts suitable for use as detergent additives in lubricating oils EP-A-450874 discloses a non-sulphurised overbased metal salt of a sulphur-free calixarene having a substituent hydroxyl group or groups available for reaction with a metal base and their preparation by reacting at elevated temperature:
(A) either (i) a sulphur-free calixarene having a substituent hydroxyl group or groups available for reaction with metal base, (ii) a low-based metal calixarate, (iii) a neutral metal calixarate or (iv) an overbased metal calixarate,
(B) a metal base added either in a single addition or in a plurality of additions at intermediate points during the reaction,
(C) a solvent comprising either
(C
1
) either (i) a polyhydric alcohol having 2 to 4 carbon atoms, (ii) a di-(C
3
or C
4
) glycol, (iii) a tri-(C
2
-C
4
) glycol or (iv) a mono- or poly-alkylene glycol alkyl ether of the formula:
R
9
(OR
10
)
f
OR
11
(III)
wherein in the formula (III) R
9
is a C
1
to C
6
alkyl group, R
10
is an alkylene group, e.g. of 1-6 or 2-4 carbon atoms, R
11
is hydrogen or a C
1
to C
6
alkyl group and f is an integer from 1 to 6, either alone or in combination with either (C
2
) a hydrocarbon solvent or (C
3
) either (i) water, (ii) C
1
to C
20
monohydric alcohol, (iii) a C
1
to C
20
ketone, (iv) a C
1
to C
10
carboxylic acid ester or (v) an aliphatic, alicyclic or aromatic C
1
to C
20
ether, or, (C
4
) a C
1
to C
4
monohydric alcohol, in combination with a hydrocarbon solvent (C
2
), and
(D) carbon dioxide added subsequent to each addition of component (B).
It is important that the process be tolerant to plant conditions, particularly in relation to the glycolation and carbonation steps, i.e. addition of (C) and (D) respectively in the process described hereinabove otherwise sediment content may be unduly high or the product may be less workable than is desirable. We have found that the robustness of the process which is a term coined to embrace tolerance to plant conditions, achievement of a workable product and acceptable sediment contents improves with increasing molecular weight of the calixarene from which the overbased metal salt is derived. A practical consequence of improved robustness is that high AV (Alkalinity Values as measured by the method of ASTM D2896) typically an AV of at least 370, for example about 450, and as high as 500, or more, are readily achievable.
Accordingly in one aspect the present invention provides an overbased metal salt of a sulphur-free calixarene having a substituent hydroxyl group or groups available for reaction with a metal base, the calixarene having a molecular weight of at least 1880.
For a review of calixarenes the reader is referred to ‘Monographs in Supramolecular Chemistry’ by C David Gutsche, Series Editor—J Fraser Stoddart, published by the Royal Society of Chemistry, 1989. Calixarenes having a substituent hydroxyl group or groups include homocalixarenes, oxacalixarenes, homooxacalixarenes and heterocalixarenes.
wherein Y is a divalent bridging group;
R
3
is hydrogen, a hydrocarbyl or a hetero-substituted hydrocarbyl group;
either R
1
is hydroxyl and R
2
and R
4
are independently either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl,
or R
2
and R
4
are hydroxyl and R
1
is either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl;
and n has a value of at least 4.
When R
1
is hydrogen, R
2
and R
4
are hydroxyl, and R
3
is either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl in the formula (I) the calixarene is a resorcinarene.
In the formula (I) Y may suitably be (CHR
6
)
d
in which R
6
is either hydrogen or hydrocarbyl, e.g. of 1-6 carbons such as methyl and d is an integer which is at least one, n preferably is at least 6, more preferably at least 3, e.g. at least 9. Any heterosubstituted hydrocarbyl group has the heteroatom, preferably —O— or ═NH, interrupting a chain of carbon atoms, such as an alkoxy-alkyl group of 2-20 carbons.
wherein R
2
and R
4
are independently either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl, R
3
is either hydrocarbyl or hetero-substituted hydrocarbyl; either one of R
7
and R
8
is hydrogen and the other is either hydrogen or hydrocarbyl, n has a value of at least 6, preferably at least 8, typically at least 9 and e is one or greater, e.g. 1-4.
Preferably in the formula (II) R
2
and R
4
are hydrogen; R
3
is hydrocarbyl, preferably alkyl of greater than 4, preferably greater than 9, more preferably greater than 12 carbon atoms; one of R
7
or R
8
is hydrogen and the other is either hydrogen or alkyl, preferably hydrogen, n is at least 8, preferably at least 9, and up to 12. Alternatively, R
3
in the formula (III) may be a hydrocarbyl group derived from a polyolefin, for example polyethylene, polypropylene, polybutylene or a polyolefin copolymer, for example an ethylene/propylene copolymer, preferably from a polyisobutene. Examples of R
3
include dodecyl and octadecyl.
A molecular weight of the calixarene of at least 1880 comprises two variable contributions, the first being that from the hydrocarbyl substituents(s) on the aromatic nucleus and the second being that from the number of units in the cyclic polymer, i.e. the value of n in the formulae (II) and (III). Thus with reference to the calixarene of the formula (III) when (CR
7
R
8
)
e
is CH
2
, R
2
and R
4
are hydrogen and R
3
is, for example octadecyl, the value of n must be for a non-homogeneous calixarene, i.e. one comprised of a number of rings of different sizes, an average of at least 5.4 and for a homogeneous calixarene, i.e. one comprised of rings of the same size, at least 6.
The metal moiety of the salts may suitably be either an alkali or an alkaline earth metal, or indeed any metal capable of forming salts with calixarenes. Preferred metals include calcium, magnesium or barium. A particularly preferred metal is calcium. Mixtures of metals may also be employed. The sal
Esposito, Esq. Michael F.
Johnson Jerry D.
Lubrizol Adibis Holdings (UK) Limited
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