Polyolefin-substituted dicarboxylic derivatives

Details Polyolefin-substituted dicarboxylic derivatives Polyolefin-substituted dicarboxylic derivatives

1999-01-14

2001-07-31

Lipman, Bernard (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C252S299010, C525S327700

Reexamination Certificate

active

06268439

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to polyolefin-substituted dicarboxylic acid ester derivatives and polyolefin substituted dicarboxylic anhydride ester derivatives which are useful as dispersant additives in lubricating oil compositions.
BACKGROUND OF THE INVENTION
UK patent No. 981,850 discloses as oil additives esters of polyisobutenylsuccinic acids which are obtained by reaction of polyisobutenylsuccinic acids with a polyol, e.g. pentaerythritol. These products have are known dispersant additives for lubricating oils, and are often referred to as “ashless” because of the absence of a metal component.
It has now been found that by using a particular class of polyols it is possible to prepare polyolefin-substituted dicarboxylic acid or anhydride ester derivatives having improved dispersancy properties when compared with the conventional ester derivatives described hereinabove.
SUMMARY OF THE INVENTION
Accordingly, the present invention, there is provided polyolefin-substituted dicarboxylic acid ester derivatives and polyolefin substituted dicarboxylic anhydride ester derivative having (a) a polyolefin substituent derived from an atactic propylene oligomer of the formula:
where n is in the range of 15 to 120, having a number average molecular weight (Mn) in the range of 700 to 5000 and molar ratio of dicarboxylic acid or dicarboxylic anhydride moieties to atactic propylene oligomer in the range of 1:1 to 1.5:1; and having (b) an ester group derived from a polyether polyol.
DESCRIPTION OF THE INVENTION
The polyether polyols may be prepared by the established reaction of one or more alkylene oxides e.g. ethylene oxide, propylene oxide, styrene oxide or epichlorohydrin with an alkane polyol for instance an alkylene diol or polyalkylene polyol.
The alkane polyols comprise at least two and preferably at least four hydroxy groups such as the trihydroxyalkanes, which includes, without limitations, ethylene glycol, propylene glycol, polymethylene glycols, trihydroxybutanes, pentanes, hexanes, heptanes, octanes, nonanes, dodecanes, which includes, without limitations, as well as tetrahydroxy alkanes, pentahydroxy alkanes, hexahydroxy alkanes, and the sugar alcohol's such as erythritol, pentaerythritol, tetritols, pentitols, hexitols, mannitol, sorbitol, sucrose, glucose and the like. Preferred polyols comprises sorbitol and glycerol or a mixture thereof. Especially preferred is sorbitol. The polyether polyols in accordance with the present invention may comprise one or more aromatic groups.
The alkylene diols or polyalkylene polyols may suitably be mixed with an amine, prior to their reaction with one or more alkylene oxides.
Suitable amines comprise amino-alcohol's, polyoxyalkylene polyamines and hydroxyamines. Preferably, the amine is an amino-alcohol.
The polyolefin-substituted dicarboxylic acid or anhydride ester derivative is suitably prepared by reacting a polyolefin-substituted dicarboxylic acid or anhydride with a polyether polyol as described hereinbefore. It will be clear that a polyether polyol comprises at least two alkoxy groups and at least two hydroxy groups.
The polyolefin-substituted dicarboxylic acid is preferably derived by reacting an alpha-beta unsaturated dicarboxylic acid with a polyolefin, suitably a homopolymer or copolymer of one or more olefin monomers having 2 to 16, preferably from 2 to 6, carbon atoms. The copolymers include random, block and tapered copolymers. Suitable monomers include ethene, propene, butenes, isobutene, pentenes, octenes, and also diolefins such as butadiene and isoprene. If a diene is used as monomer the resulting polymer is preferably hydrogenated to saturate at least 90%, more preferably substantially all unsaturated bonds. It is especially preferred to use polyolefin substituents derived from polyisobutylene or (atactic) polypropylene.
The polyolefin substituent may derive from any polyisobutylene.
Suitable polyisobutylene substituents include those disclosed in for instance UK 981,850, UK 2,081,274, UK 2,231,873 and EP-A-0 208 560 which are hereby fully incorporated by reference.
The polyolefin substituent may derive from any atactic propylene oligomer. Suitably, the polyolefin substituent is derived from the atactic polypropylene as described and claimed in EP-B-0 490 454 which document is hereby fully incorporated by reference.
The alkenyl-substituted dicarboxylic acid or anhydride ester derivative has a polyolefin substituent derived from an atactic propylene oligomer substantially of the formula
where n is in the range of 15 to 120, having number average molecular weight (M
n
) in the range of 700 to 5000, and molar ratio of dicarboxylic acid or dicarboxylic anhydride moieties to atactic propylene oligomer in the range of 1:1 to 1.5:1. The number average molecular weight (M
n
) of the polyolefin substituent is suitably not greater than 5000, since molecular weights above 5000 can give handling problems in the reaction due to the viscosity levels. To reduce the risk of problems the number average molecuilar weight is preferably below 3000 but above 700 since low molecular products tend to be less effective as dispersants. More preferably, M
n
is in the range 900 to 2500.
The number average molecular weight can easily be determined by vapour pressure osmometry or by gel permeation chromatography with calibration of the polymer, as will be appreciated by those skilled in the art.
The weight average molecular weight (M
w
) can also be determined by gel permeation chromatography. The quotient M
w
/M
n
, which is a measure indicating the width of molecular weight distribution, has a value from 1.5 to 4.0.
The dicarboxylic acid is suitably derived from an alpha-beta unsaturated dicarboxylic acid, anhydride or ester, such as maleic, fumaric, itaconic, water maleic acid and anhydride being particularly preferred, in which case the dicarboxylic acid grouping in the present product is thus a succinic acid derivative.
Preferably, the polyolefin-succinic type derivatives in accordance with the present invention have a molar equivalent ratio of succinic groups to polyolefin groups of below 1.3. Such derivatives show particularly useful properties, including a reduced level of interaction with other additives normally present in lubricating oil packages, and moreover give good results in the more severe engine test VE. Preferably, the molar equivalent ratio of dicarboxylic acid producing groups to polyolefin groups is between 1.0 and 1.2.
It should be understood that for the purposes of the present invention the “molar equivalent ratio” is the molar ratio in the actual product of dicarboxylic acid or anhydride groupings to equivalents of polyolefin substituent. The molar equivalent ratio (r) can be easily calculated by the following expression:
r
=
M
n
×
AV
(
20
×
AM
-
AV
×
96
)
in which:
M
n
=Number average molecular weight of the polyolefin
AV=Acid value of the reaction product (mmol/g)
AM=Active matter in the reaction product (% m)
“Active matter” denotes polyolefins bearing carboxylic acid groupings, from which it will be understood that the unreacted nonpolar polyolefins do not contribute to the AM.
The molar ratio of dicarboxylic acid or anhydride groups to polyether polyol groups in the derivatives of the present invention is suitably in the range of 0.5 to 10, preferably in the range of 0.6 to 3, more preferably 0.8 to 2.2.
In accordance with the present invention, the polyolefin-substituted dicarboxylic or anhydride derivatives of the invention may be prepared by a process which comprises reacting a polyolefin-substituted dicarboxylic or anhydride as defined hereinabove with a polyether polyol.
The molar ratio of polyolefin-substituted dicarboxylic acid or anhydride to polyether polyol used in the present process may vary between wide limits. Suitably, the molar ratio of polyolefin-substituted dicarboxylic acid or anhydride to polyether polyol is in the range of 0.5 to 10, preferably 0.6 to 3. The reaction temperature may also vary between wide limits with reac

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