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(11) | EP 0 048 631 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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Viscosity index improver additive composition Den Viskositätsindex verbessernde Additivzusammensetzung Composition d'additif améliorant l'indice de viscosité |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] The present invention relates to a viscosity index improver additive composition and to a finished lubricating oil containing the additive composition.
[0002] Lubricating oils are normally classified in terms of their viscosity at some standard temperature but equally important is a property known as the viscosity index, which is an empirical number giving a measure of the extent to which the viscosity of an oil decreases as the temperature is raised. An oil which satisfies viscosity requirements at both extremes of the temperature range to which it may be subjected is said to have a high "viscosity index". This property can be controlled to some extent by refining, but in recent years the trend has been towards 'multi-grade' oils, of extremely high viscosity index, in which certain polymer compounds which function as viscosity index improvers are added. In addition to the properties of improving viscosity index and of being stable under conditions of high shear, it is necessary for any potential lubricating oil additives to have two other important properties, namely compatibility with the lubricating oil and the stability under conditions of oxidation which might reasonably be expected to be encountered under conditions of storage and use of such compositions.
[0003] Recently, there has been developed a series of effective viscosity index improving agents for lubricating compositions based upon various alkenylarene/conjugated diene interpolymers which are generally hydrogenated to improve their oxidative stability. These interpolymer additives are based upon several types of alkenylarene/conjugated diene copolymers which differ from each other, principally, in the steric arrangement of the polymerised monomers. On the one hand US Patent Nos. 3554911 (Schiff et al.), 3630905 (Sorgo), USP 3752767 (Eckert) and 3772169 (Small et al.), to select but a few, are concerned with the use of hydrogenated random butadiene/styrene copolymers as VI improvers for lubricating oils. These copolymers are prepared by the copolymerisation, using conventional techniques, of butadiene and styrene in the presence of a randomising agent and subsequently the copolymers are partially hydrogenated. On the other hand US Patent Nos. 3994815 (Coleman), 3775329 (Eckert), 3668125 (Anderson) and 3763044 (Anderson), for example are concerned with the use of hydrogenated block and tapered copolymers of an alkenylarene, e.g. styrene or alphamethylstyrene and a conjugated diene, e.g. butadiene or isoprene as viscosity index improver additives. These polymers are composed of essentially pure blocks of the individual polymers and are prepared by anionic polymerisation techniques, followed in most cases by hydrogenation.
[0004] The difficulties encountered during the formulation of certain lubricating compositions containing these copolymers have been extensively enumerated in for example US Patent Nos. 3630905 (Sorgo), 3772169 (Small et al.) and 3668125 (Anderson) and the complete specification of UK Patent No. 1540292 (Lubrizol). All these specifications suggest solutions to these problems. The Sorgo specification discloses the preparation of an oil-extended composition comprising (a) 40-60 weight percent of the particular hydrogenated copolymer and (b) 60-40 weight percent of a paraffin oil. Large amounts of this oil-extended composition are prepared in one operation and smaller amounts, as needed, are used in the preparation of the final lubricating compositions. The Small et al. patent is concerned with the prevention of a gelling tendency that mineral lubricating oil or ester type oil compositions containing these hydrogenated copolymers have. Their proposed solution is the addition of small amounts of a polyester of an olefinically unsaturated acid to the oil solution. GB 1540292 teaches that many of the difficulties encountered in formulating lubricating compositions containing hydrogenated interpolymers may be eliminated or diminished by first preparing an additive concentrate using a synthetic substantially hydrocarbon alkylated-aromatic lubricating oil diluent or carrier. Optionally supplemental diluents selected from ester synthetic lubricating oils, mineral lubricating oils and mixtures thereof may be employed.
[0005] We have found that the compatibility of hydrogenated alkenylarene/conjugated diene interpolymers in synthetic ester lubricating oils can be considerably improved by the addition of a mineral lubricating oil.
[0006] Accordingly the present invention provides a viscosity index improver additive composition which composition comprises from 1 to 25% by weight of a hydrogenated alkenylarene/conjugated diene interpolymer having a number average molecular weight greater than 20,000, from 30 to 72% by weight of a synthetic ester lubricating oil comprising an alkyl ester of a saturated aliphatic carboxylic acid and from 15 to 50% by weight of a non-synthetic mineral lubricating oil, all percentages by weight being expressed in terms of the total weight of the composition.
[0007] With regard to the hydrogenated alkenylarene/ conjugated diene interpolymer the alkenylarene may be a vinyl mono-, di- or polyaromatic compound such as styrene or vinyl naphthalene, preferably styrene, alkylated styrene or halogen- substituted styrene, and the conjugated diene may be butadiene or isoprene. The interpolymer may be a random, block, or star-shaped copolymer. All these terms are well-known in the art and include such polymers as are described in the aforesaid patent specifications which are herein incorporated by reference.
[0008] Suitable methods of hydrogenation are described for example in US Patent Nos. 3113986, 3205278 and 2864809. The object of hydrogenation is to saturate the olefinic double bonds in preference to the aromatic nucleus double bonds. Preferably more than 95% of the olefinic double bonds and less than 5% of the aromatic nucleus double bonds are hydrogenated. Suitably the interpolymer has a number average molecular weight in the range 20,000 to 125,000, preferably from 25,000 to 100,000. A particularly suitable copolymer is a hydrogenated styrene/isoprene block copolymer of number average molecular weight in the range 50,000 to 100,000 and containing about 75% isoprene and 25% styrene, greater than 95% of the isoprene component being present in the 1,4- form in which greater than 95% of the olefinic double bonds are hydrogenated and the styrene component having less than 5% of the aromatic nucleus double bonds hydrogenated. Preferably the vinylarene/ conjugated diene interpolymer forms from 2 to 15% by weight of the composition.
[0009] The alkyl ester of a saturated aliphatic carboxylic acid may suitably be a simple ester, diester, partial ester or complex ester formed from one or more C10 to C18 saturated organic mono- or polycarboxylic acids and one or more C3 to Cg mono- or polyhydric alcohols. Preferably the ester is formed from two molecular proportions of a monohydric alcohol and one molecular proportion of a dicarboxylic acid, e.g. di(octyl) dodecane dioate. Preferably the synthetic ester lubricant is present in an amount in the range from 50 to 72% by weight.
[0010] The non-synthetic mineral lubricating oil may suitably be the common solvent-treated or acid- treated mineral oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Preferred oils are the Solvent Neutral oils and in particular 150 Solvent Neutral oil.
[0011] A particularly preferred composition comprises 4.5% by weight of a hydrogenated styrene/isoprene block copolymer of number average molecular weight in the range 50,000 to 100,000 and containing about 75% isoprene and 25% styrene, greater than 95% of the isoprene component being present in the 1,4- form in which greater than 95% of the olefinic double bonds are hydrogenated and the styrene component having less than 5% of the aromatic nucleus double bonds hydrogenated, hereinafter referred to as 'hydrogenated styrene/isoprene tapered' (HSIT) interpolymer, 70% by weight di(octyl) dodecane dioate and 25.5% by weight 150 Solvent Neutral lubricating oil.
[0012] It has also been unexpectedly found that the proportion of non-synthetic mineral lubricating oil can be decreased and the proportion of synthetic ester lubricating oil increased by incorporating a small proportion of an olefinic homo-or copolymer such as an ethylene/propylene/non- conjugated diolefin terpolymer or a polybutene, particularly a polybutene, in the composition.
[0013] Accordingly the invention also provides a viscosity index improver additive composition as hereinbefore described modified in the respects that the amount of synthetic ester lubricating oil is in the range from 40 to 80% by weight, the amount of non-synthetic mineral lubricating oil is in the range from 15 to 40% by weight and there is included from 1 to 25% by weight of an olefinic polymer.
[0014] The olefinic polymer may be a homopolymer or a copolymer. Preferably the olefinic polymer is a polybutene of which polyisobutene is preferred. Suitable polybutenes may have a number average molecular weight in the range from 100 to 50,000.
[0015] According to another aspect of the present invention there is provided a finished lubricating oil composition comprising a major proportion of a lubricating oil base and a minor proportion of the viscosity index improver additive composition as described hereinbefore.
[0016] The lubricating oil base may be derived from a variety of sources. Thus the base oil may be derived from natural or synthetic sources which include animal oils, vegetable oils, mineral oils, synthetic hydrocarbon oils and synthetic ester oils.
[0017] The amount of the additive composition present in the finished lubricating oil composition is an amount sufficient to improve the viscosity index of the composition. Generally from 0.05 to 10% by weight of the additive composition may be used, though in certain specialised applications up to 15% by weight may be required.
[0018] In addition to the viscosity index improver additive composition the finished lubricating composition may also contain other additives conventionally employed in the art, such as dispersants, detergents, corrosion inhibitors, anti-wear agents, etc.
Example 1
[0020] A composition composed of 10% by weight of a commercially available HSIT interpolymer, 60% by weight di(octyl) dodecane dioate and 30% by weight 150 Solvent Neutral oil was found to be compatible.
Comparison Test 1
[0021] The same commercially available HSIT as used in Example 1 was found to be incompatible with di(octyl) dodecane dioate at all concentrations.
Comparison Test 2
[0022] A composition composed of 5.6% by weight of the HSIT as used in Example 1, 85% by weight di(octyl) dodecane dioate and 9.4% by weight Solvent Neutral oil resulted in separation i.e. it formed incompatible composition.
Comparison Test 3
[0023] A composition composed of 5.0% by weight of the HSIT as used in Example 1, 75% by weight of di(octyl) dodecane dioate and 20% by weight Solvent Neutral oil was incompatible.
Example 2
[0024] A composition containing 5.0% by weight of the HSIT as used in Example 1, 75.0% by weight of di(octyl) dodecane dioate, 2.0% by weight of a solution of a polybutene having a number average molecular weight in the range 30,000 to 42,000 in 150 Solvent Neutral base oil, the polybutene forming 45% by weight of the solution and 18.0% by weight 150 Solvent Neutral base oil was compatible.
Comparison Test 4
[0025] 5% by weight of a commercially available random styrene/butadiene interpolymer having a number average molecular weight greater than 20,000 in di(octyl) dodecane dioate gave a cloudy solution, i.e. the composition was incompatible.
Example 3
[0026] 20% by weight of the same styrene/butadiene interpolymer as was used in Comparison Test 4, 60% by weight di(octyl) dodecane dioate and 20% 100 Solvent Neutral base oil were mixed to form a compatible solution.
Example 4
1. A viscosity index improver additive composition which composition comprises from
1 to 25% by weight of a hydrogenated alkenylarene/ conjugated diene interpolymer having
a number average molecular weight greater than 20,000, from 30 to 72% by weight of
a synthetic ester lubricating oil comprising an alkyl ester of a saturated aliphatic
carboxylic acid and from 15 to 50% by weight of a non-synthetic mineral lubricating
oil, all percentages by weight being expressed in terms of the total weight of the
composition.
2. A composition according to claim 1 wherein the alkyenylarene is styrene, and the
conjugated diene is either butadiene or isoprene.
3. A composition according to any one of the preceding claims wherein the interpolymer
is a hydrogenated styrene/isoprene block copolymer of number average molecular weight
in the range 50,000 to 100,000 containing about 75% isoprene and 25% styrene, greater
than 95% of the isoprene component being present in the 1,4- form in which greater
than 95% of the olefinic double bonds are hydrogenated and in which less than 5% of
the aromatic nucleus double bonds in the styrene component are hydrogenated.
4. A composition according to any one of the preceding claims wherein the interpolymer
forms from 2 to 15% by weight of the composition.
5. A composition according to any one of the proceding claims wherein the alkyl ester
is a simple ester, a diester, a partial ester or a complex ester formed from one or
more C10 to C18 saturated organic mono- or polycarboxylic acids and one or more C3 to Cg mono- or polyhydric alcohols.
6. A composition according to claim 5 wherein the ester is formed from two molecular
proportions of a monohydric alcohol and one molecular proportion of a dicarboxylic
acid.
7. A composition according to any of the preceding claims wherein the synthetic ester
is present in an amount in the range from 50 to 72% by weight.
8. A composition according to any one of the preceding claims wherein the non-synthetic
mineral lubricating oil is a Solvent Neutral oil.
9. A composition according to any one of the preceding claims comprising 4.5% by weight
of a hydrogenated styrene/isoprene block copolymer of number average molecular weight
in the range 50,000 to 100,000 and containing about 75% isoprene and 25% styrene,
greater than 96% of the isoprene component being present in the 1,4- form in which
greater than 95% of the olefinic double bonds are hydrogenated and the styrene component
having less than 5% of the aromatic nucleus double bonds hydrogenated, 70% by weight
di(octyl) dodecane dioate and 25.5% by weight 150 Solvent Neutral lubricating oil.
10. A viscosity index improver additive composition as claimed in any one of the preceding
claims modified in the respects that the amount of synthetic ester lubricating oil
is in the range from 40 to 80% by weight, the amount of non-synthetic mineral lubricating
oil is in the range from 15 to 40% by weight and there is included from 1 to 25% by
weight of an olefinic polymer.
11. A composition according to claim 10 wherein the olefinic polymer is a polybutene.
12. A finished lubricating oil composition comprising a major proportion of a lubricating
oil base and a minor proportion of the viscosity index improver additive composition
as claimed in any one of the preceding claims.
13. A finished lubricating oil composition according to claim 12 wherein the additive
is present in an amount in the range from 0.05 to 15% by weight.
1. Den Viskositätsindex verbessernde Additivzusammensetzung aus 1 bis 25 Gew.-% eines
Interpolymers aus hydrierten Alkenylaren/conjugiertem Dien mit einem Zahlendurchschnitts-Molekulargewicht
größer als 20 000, 30 bis 72 Gew.-% eines synthetischen Esterschmieröls aus einem
Alkylester einer gesättigten aliphatischen Carbonsäure und 15 bis 50 Gew.-% eines
nichtsynthetischen mineralischen Schmieröls, wobei sich alle Gewichtsprozentangaben
auf das Gesamtgewicht der Zusammensetzung beziehen.
2. Zusammensetzung gemäß Anspruch 1, worin das Alkenylaren Styrol ist und das conjugierte
Dien entweder Butadien oder Isopren ist.
3. Zusammensetzung gemäß einem der vorgehenden Ansprüche, worin das Interpolymer ein
Block-Copolymer aus hydriertem Styrol/Isopren mit einem Zahlendurchschnitts-Molekulargewicht
im Bereich von 50 000 bis 100 000 enthaltend etwa 75 % Isopren und 25 % Styrol darstellt,
wobei mehr als 95 % der Isopren-Komponente in der 1,4- Form anwesend ist, in der mehr
als 95 % der olefinischen Doppelbindungen hydriert sind und weniger als 5 % der aromatischen
Kern-Doppelbindungen in der Styrolkomponente hydriert sind.
4. Zusammensetzung gemäß einem der vorgehenden Ansprüche, worin das Interpolymer 2
bis 15 Gew.-% der Zusammensetzung ausmacht.
5. Zusammensetzung gemäß einem der vorgehenden Ansprüche, worin der Alkylester ein
einfacher Ester, ein Diester, ein partieller Ester oder ein komplexer Ester aus ein
oder mehreren C10 bis C18 gesättigten organischen Mono- oder Polycarbonsäuren und einem oder mehreren C3 bis Cg mono- oder mehrwertigen Alkoholen ist.
6. Zusammensetzung gemäß Anspruch 5, worin der Ester gebildet ist aus zwei molekularen
Anteilen eines einwertigen Alkohols und einem molekularen Anteil einer Dicarbonsäure.
7. Zusammensetzung gemäß einem der vorgehenden Ansprüche, worin der synthetische Ester
anwesend ist in einer Menge im Bereich von 50 bis 72 Gew.-%.
8. Zusammensetzung gemäß einem der vorgehenden Ansprüche, worin das nicht-synthetische
mineralische Schmieröl ein Solvent Neutral Öl ist.
9. Zusammensetzung gemäß einem der vorgehenden Ansprüche umfassend 4,5 Gew.-% eines
Block-Copolymers aus hydriertem Styrol/ Isopren mit einem Zahlendurchschnitts-Molekulargewicht
im Bereich von 50 000 bis 100 000 enthaltend etwa 75 % Isopren und 25 % Styrol, wobei
mehr als 96 % der Isoprenkomponente in der 1,4- Form vorliegen in welcher mehr als
95 % der olefinischen Doppelbindungen hydriert sind und in der Styrolkomponente weniger
als 5 % der aromatischen Kern-Doppelbindungen hydriert sind, 70 Gew.-% Di(octyl)dodecandioat
und 25,5 Gew.-% 150 Solvent Neutral Schmieröl.
10. Den Viskositätsindex verbessernde Additivzusammensetzung gemäß einem der vorgehenden
Ansprüche, dadurch modifiziert, daß die Menge an synthetischem Esterschmieröl im Bereich
von 40 bis 80 Gew.-%, die Menge an nichtsynthetischem mineralischem Schmieröl im Bereich
von 15 bis 40 Gew.-% liegen und 1 bis 25 Gew.-% eines olefinischen Polymers zugesetzt
ist.
11. Zusammensetzung gemäß Anspruch 10, worin das olefinische Polymer ein Polybuten
ist.
12. Eine fertige Schmierölzusammensetzung enthaltend einen größeren Anteil einer Schmierölbasis
und einen kleineren Anteil der den Viskositätsindex verbessernden Additivzusammensetzung
gemäß einem der vorgehenden Ansprüche.
13. Eine fertige Schmierölzusammensetzung gemäß Anspruch 12, worin das Additiv anwesend
ist in einer Menge im Bereich von 0,05 bis 15 Gew.-%.
1. Composition d'additif améliorant l'indice de viscosité, cette composition comprenant
de 1 à 25 % en poids d'un interpolymère alcénylarène/ diène conjugée hydrogéné ayant
un poids moléculaire moyen en nombre supérieur à 20 000, de 30 % à 72 % en poids d'une
huile lubrifiante synthétique de type ester comprenant un ester alkylique d'un acide
carboxylique aliphatique saturé et de 15 à 50 % en poids d'une huile lubrifiante minérale
non synthétique, tous les pourcentages en poids étant exprimés par rapport au poids
de la composition.
2. Composition selon la revendication 1, dans laquelle l'alcénylarène est le styrène,
et le diène conjugué est le butadiène ou l'isoprène.
3. Composition selon l'une quelconque des revendications précédentes, dans laquelle
l'interpolymère est un copolymère séquencé styrène/ isoprène hydrogéné, ayant un poids
moléculaire moyen en nombre compris entre 50 000 et 100 000, contenant environ 75
% d'isoprène et 25 % de styrène, plus de 95 % du composant isoprène étant présents
sous la forme 1,4 et 95 % des doubles liaisons oléfiniques étant hydrogénés et moins
de 5 % des doubles liaisons du noyau aromatique du styrène étant hydrogénés.
4. Composition selon l'une quelconque des revendications précédentes, dans laquelle
l'interpolymère forme de 2 à 15 % du poids de la composition.
5. Composition selon l'une quelconque des revendications précédentes, dans laquelle
l'ester alkylique est un ester simple, un diester, un ester partiel ou un ester complexe
formé à partir d'un ou plusieurs acides mono- ou poly- carboxyliques organiques saturés
en Cl,) à C18 et à partir d'un ou plusieurs mono- ou poly- alcools en C3 à Cg.
6. Composition selon la revendication 5, dans laquelle l'ester est formé à partir
de deux proportions moléculaires d'un monoalcool et d'une proportion moléculaire d'un
acide dicar- boxylique.
7. Composition selon l'une quelconque des revendications précédentes, dans laquelle
l'ester synthétique est présent en une quantité comprise entre 50 et 72 % en poids.
8. Composition selon l'une quelconque des revendications précédentes, dans laquelle
l'huile minérale lubrifiante non synthétique est de l'huile "Solvant Neutre".
9. Composition selon l'une quelconque des revendications précédentes, comprenant 4,5
% en poids d'un copolymère séquencé styrène/ isoprène, hydrogéné, ayant un poids moléculaire
moyen en nombre compris entre 50 000 et 100 000 et contenant environ 75 % d'isoprène
et 25 % de styrène, plus de 96 % du composé isoprène étant présents sous forme 1,4
et plus de 95 % des doubles liaisons oléfiniques étant hydrogénés et le composant
styrène ayant moins de 5 % des doubles liaisons du noyau aromatique hydrogénés, 70
% en poids de dodécane dioate de di(octyle) et 25,5 % en poids d'huile lubrifiante
"Solvant Neutre 150".
10. Composition d'additif améliorant l'indice de viscosité, selon l'une quelconque
des revendications précédentes, modifiée du fait que la quantité de l'huile lubrifiante
synthétique de type ester se situe entre 40 et 80 % en poids, la quantité de l'huile
lubrifiante minérale non synthétique se situant entre 15 et 40 % en poids, et la composition
comporte 1 à 25 % en poids d'un polymère oléfinique.
11. Composition selon la revendication 10, dans laquelle le polymère oléfinique est
un polybutène.
12. Composition d'huile lubrifiante terminée comprenant une proportion majeure d'une
huile lubrifiante de base et une proportion mineure de la composition d'additif améliorant
l'indice de viscosité telle que revendiquée dans l'une quelconque des revendications
précédentes.
13. Composition d'huile lubrifiante terminée selon la revendication 12, dans laquelle
l'additif est présent en une quantité comprise entre 0,05 et 15 % en poids.