GB1559952A

GB1559952A - Lubricating oil compositions

Info

Publication number: GB1559952A
Application number: GB44555/77A
Authority: GB
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1977-10-26
Filing date: 1977-10-26
Publication date: 1980-01-30
Also published as: NL7810586A; NL190644B; FR2407259B1; DK150547B; CH638559A5; ATA761778A; JPS6224480B2; AT366091B; DE2846253C2; SE7811066L; CA1117517A; JPS5470305A; BE871277A; DE2846253A1; NL190644C; FR2407259A1; DK150547C; SE431225B; DK471778A

Abstract

The mixture contains a hydrocracked lubricating oil as the base oil and also a) an oil-soluble polyalkyl (meth)acrylate having viscosity index-improving properties and a mean molecular weight (weight average) from 10<3> to 10<6>, in which more than 75 per cent by weight of the alkyl chains have 12 to 15 carbon atoms, in a concentration from 0.001 to 20 per cent by weight and b) an oil-soluble polyalkyl (meth)acrylate having pour point-lowering properties and a mean molecular weight (weight average) from 10<3> to 10<6>, in which at most 75 per cent by weight of the alkyl chains have 12 to 15 carbon atoms and 10 to 90 per cent by weight of the alkyl chains have at least 16 carbon atoms, in a concentration from 0.001 to 5 per cent by weight. Due to the presence of these two additives, a lowering of the pour point is achieved which is greater than that achievable with only the additive b).

Description

(54) LUBRICATING OIL COMPOSITIONS (71) We, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V., a company organised under the laws of the Netherlands, of 30 Carel van Bylandtlaan, The Hague, The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to lubricating oil compositions comprising a hydrocracked lubricating oil as a base oil and a mixture of certain oil-soluble polyalkyl(meth)acrylates as pour point depressants.

Hydrocracked lubricating oils such as the oils described in Netherlands patent application 7613854 can be obtained with a very high viscosity index (V.I.) and are therefore particularly suitable as base oils for multigrade engine oil formulations, especially multigrade gasoline and diesel engine oils.

However, for hydrocracked base oils of the extra high V.I. type (XHVI oils having a VI of at least 140 (ASTM D-2270)) it appeared not possible to reduce the pour point which normally is e.g. about -15 C to -330C (ASTM D-97) or lower as required by the current demands for e.g. cold climates, even when using pour point depressants especially designed for use in HVI oils, including hydrocracked HVI oils, such as the polyalkylmethacrylates described in British patent 1,347,713.

These polyalkylmethacrylates have an average number molecular weight between 2 x 103 and 106, an average number of carbon atoms in the alkyl chains containing 9-18 carbon atoms of 12.4 to 13.7 and at least 6 alkyl chains with a different number of carbon atoms among the alkyl chains containing 9-18 carbon atoms. It has now been found that this problem can be solved by using a special combination of two classes of polyalkyl(meth)acrylates.

Thus the invention relates to a lubricating oil composition comprising a hydrocracked lubricating oil as a base oil and a) 0.00120%w of an oil-soluble polyalkyl(meth)acrylate with VI improving properties, more than 75%w of the alkyl chains having 12-15 C-atoms, the weight average molecular weight being 103--10, and b) 0.001-5%w of an oil-soluble polyalkyl(meth)acrylate with pour point depressing properties, at most 75%w of the alkyl chains having 12-15 C-atoms and 1090%w of the alkyl chains having at least 16 carbon atoms, the weight average molecular weight being 103103.

US patent 2,655,479 already discloses that a synergistic pour point depressing effect can be obtained if a mixture of two classes of polyalkylmethacrylates is used.

This mixture principally contains polyalkylmethacrylates with alkyl chains containing 8-18 C-atoms, the average alkyl chain length being about 12.7 and about 13.5, respectively, for the two classes of polymers. This patent is directed to solvent extracted (conventional) oils and nothing is said about the present problem of depressing the pour point of a hydrocracked lubricating oil (unconventional oil).

The lubricating base oil can be a hydrocracked base oil as described in Netherlands patent application 7613854 including the XHVI oils, the present invention is particularly concerned with. It preferably has a VI of at least 120, more preferably at least 140.

These base oils may be blended with other oils, such as solvent extracted lubricating oils, animal or vegetable oils, synthetic oils, such as polyolefins, ester oils or polyo syalkylene oils, or with residual fractions, such as bright stock, or with hydrotreated fractions, such as hydrotreated extracts of distillates or residues.

Additives (a) can act as a VI-improver and if no other VI improver is present a proportion of 1-10%w is preferred. If another Vi improver is used normally 0.05-l%w of additive (a) is sufficient to obtain the synergistic pour point depressant effect with additive (b).

The alkyl chains containing 12-15 carbon atoms are preferably derived from a mixture of branched and unbranched synthetic alcohols, obtained by hydroformylation, in particular by reacting a mixture of olefins containing 11-14 carbon atoms, with carbon monoxide and hydrogen in the presence of a complex catalyst consisting of cobalt, carbon monoxide and a phosphorous compound.

Normally the latter alcohols contain 5-25Vw branched alkyl chains. In additives (a) at most 25%w of the alkyl(meth)acrylates may be derived from other alcohols, in particular primary alcohols, such as synthetic (unbranched and branched, e.g.

5--25%w branched) Cs~t,-alcohols, synthetic or preferably natural (unbranched) C16-18-alcohols, lower alcohols having 1-8 carbon atoms or alcohols having more than 18 carbon atoms.

Additives (a) containing in addition to one or more of the above-mentioned monomers a small amount, e.g. at most 100w, of polar monomers such as substituted or unsubstituted vinyl pyridines, substituted or unsubstituted vinyl pyrrolidones or hydroxyl group-containing monomers.

Additives (a) can have weight average molecular weights (Mw) of 2 x 103 to 104, in particular of 5 x 104 to 5 x 105. They preferably have a low molecular weight distribution range to provide a good shear stability, which means that Q = Mw/lWn (Mn = number average molecular weight) should be low, e.g. 1.5-5, such as 2-4.

If desirable they may be pre-sheared.

As mentioned above suitable additives (a) have VI improving properties.

Although they can also act as pour point depressants it will be shown that additives (a) alone do not substantially improve the pour point of XHVI oils.

Preferred additives (b) are described in British patents 1,163,807 and in particular 1,347,713. This means that the C,2~,5-alkyl chains are preferably of the type described above for additives (a), whereas the other alkyl chains are preferably derived from synthetic C9-11-alcohols and/or synthetic or preferably natural C16-18-alcohols and optionally C,~8-alcohols or alcohols having more than 18 carbon atoms. The presence of C, > 18-alcohols in proportions of at least 10%w is particularly desirable. A small amount e.g. at most 10%w, of polar monomers, such as described for additives (a), can also be present.

Preferred proportions of additive (b) are 0.01-2%w. Additives (b) can have weight average molecular weights (Mw) of 2 x 103 to 104, in particular 2 x 104 to 5 x 105. They preferably have a low Q value of e.g.

1.5-5, such as 2-4.

Additives (a) and (b) can be added, as such or in the form of a concentrate of (a) and/or (b) in a carrier oil to the base oils. The concentrate may e.g. contain 20-75%w (a) and/or (b) in e.g. a mineral lubricating oil as carrier oil.

Other additives can also be used, such as antioxidants, detergents, other VI improvers, anti-corrosion agents, extreme pressure agents, anti-foaming agents, etc.

The invention is illustrated by the following examples.

The additives according to the invention were tested in various hydrocracked base oils.

Base oil 1: a hydrocracked lubricating oil having a pour point of-15 C and a VI of 149.

Base oil 2: base oil 1 + commercial gasoline engine oil additive package.

Base oil 3: 88%w base oil 1 + 12%w hydrotreated bright stock (VI of 95) (VI of mixture being 144).

Base oil 4: base oil 3 + package of base oil 2.

Base oil 5: 89%w base oil 1 + 11%w of above hydrotreated bright stock + commercial diesel engine oil additive package including a VI improver (a hydrogenated styrene/isoprene block copolymer).

Additives a1: Poly C12-15-alkylmethacrylate derived from branched and unbranched (weight ratio 15:85)synthetic C12-15-alcohols(20%w C12, 30%w C13, 30%w C14 and 20%w C15). Mn = 1.35 x 105; Mw = 5.35 x 105; Q = 4.0.

Additive a2: random copolymer of 92.3%w C12-15-alkylmethacrylate (see additive a1) and 7.1%w 2-vinylpyridine. Mw = 63,000; Mn = 223,000; Q = 2.8.

Additive a3:copolymer of 98.0%wC12-15-alkylmethacrylate (see additive a1), 0.9%w C9-11-alkylmethacrylate (see additive b1) and 1.1%W C16-18-alkylmethacrylate (see additive b1).w = 310,000;n = 93,700; Q = 3.3.

Additive b1: poly C9-18-alkylmethacrylate derived from 43.5%w branched and unbranched (weight ratio 15:85) synthetic C9-11-alcohols (20%w C9, 50%w C10 and 30%w C11), 10.0%w (C12-15-alcohols (see additive a1) and 44.5%w natural C16-18alcohols (30%w C16 and 58%w C18). Mw = 420,000; Mn = 55,000; Q = 7.7.

Additive b2: same composition as additive b,, but:n = 21,200; Mw =46,500; Q = 2.2.

EXAMPLE 1 (base oil 1) TABLE 1 (pour points 'C) %wb1 %w a1 0 0.1 0.2 0.3 0 -15 -21 -21/-24 0.1 -15 -24 -24 0.2 -15 -24/-27 -30 -30 0.3 -15 -27 -30 0.4 -15 -30 -33 EXAMPLE II (base oil 2) TABLE 2 (pour points C) %w b2 %w1 0 0.1 0.2 0 -15 -21 -24 4.0 -15 -36 -36 EXAMPLE III TABLE 3 (pour points C)

%w b1 %w b2 Base oil %w a1 0 0.03 0.05 0.1 0.2 0.4 0 0.03 0.05 0.1 0.2 0.4 0.6 3 0 -12 - - - - -27 - - - - - -30 3 7.4 -27 -33 -33 -36 -36 -33 -27 -33 -33 -33 -33 -33 4 7.4 -18 -33 -33 -33 -33 -33 -18 -33 -33 -33 -33 -33 5 0 -12 - - -24 -24 -27 -12 -24 -27 -27 5 0.4 - - - - -30 -30 - -27 - -30 -30 -30 -30 5 0.6 -12 -18 -30 -33 -33 -33 -12 -27 -30 -33 -33 -33 5 0.8 -15 -27 -33 - -33 -33 -15 -33 -33 - -33 -33 EXAMPLE IV (base oil 2) TABLE 4 (pour points C) %w b2 additive %w 0 0.1 0.2 a2 0 -15 -21 -24 4.0 -15 -36 a3 0 -15 -21 -24 4.0 -21 -36 -36

Claims

WHAT WE CLAIM IS:

1. A lubricating oil composition comprising a hydrocracked lubricating oil as a base oil and a) 0.001-20%w of an oil-soluble polyalkyl(meth)acrylate with VI improving properties, more than 75%w of the alkyl chains having 12-15 C-atoms, the weight average molecular weight being 10 -105, and b) 0.001-5%w of an oil-soluble polyalkyl(meth)acrylate with pour point depressing properties, at most 75%w of the alkyl chains having 12-15 C-atoms and 1090%w of the alkyl chains having at least 16 carbon atoms, the weight average molecular weight being 104-104.

2. Composition as claimed in claim 1, in which the viscosity index of the hydrocracked base oil is at least 120.

3. Composition as claimed in any one of the preceding claims, in which additive (a) is a polyalkylmethacrylate having branched and unbranched chains; with 12-15 carbon atoms.

4. Composition as claimed in any one of the preceding claims, in which additive (a) and/or (b) are derived from monomers at most 10% w of which are polar monomers.

5. Composition as claimed in any one of the preceding claims, in which additive (b) is a polyalkylmethacrylate with at least six different alkyl groups having 9-18 carbon atoms.

6. Composition as claimed in any one of the preceding claims, in which additive (b) is a polyalkylmethacrylate in which the alkyl groups are derived from alcohols with branched and unbranched chains and 9-15 carbon atoms and straight chain alcohols with 16 and 18 carbon atoms.

7. Composition as claimed in any one of the preceding claims, in which the alkyl groups containing 9-15 carbon atoms have 525%w branched chains.

8. Composition as claimed in any one of the preceding claims, in which the ratio of the weight average to the number average molecular weight (Q-factor) of the additives (a) and (b) is between 1.5 and 5.

10. Composition as claimed in claim 1 substantially as hereinbefore described with special reference to the Examples.

11. A concentrate of the additives (a) and (b) as defined in anyone of the preceding claims in a carrier oil.