NO122198B - - Google Patents

Description

Lubricating oil composition.

This invention relates to a lubricating oil composition for cylinder lubrication in engines with separate cylinder and crankshaft

lubrication, containing a lubricating oil and lubricating oil additives.

Lubrication of cylinders and pistons in engines with separate

lubrication of the cylinder and weighing shaft causes problems that are not encountered when lubricating the cylinder and piston from the crankcase.

These problems are mainly due to the lubrication system used

for engines with separate lubrication of cylinders and crankshaft:

The lubricating oil to lubricate the cylinder and piston is pressed between the pistons

and cylinder through one or more holes in the cylinder wall and is then lost, e.g. by combustion via the exhaust or by leakage along the piston. With this so-called "one-time" lubrication, lubrication is selected

the amount of oil as low as possible to limit the consumption of lubricating oil as much as possible. This leads to difficulties unknown to other types of engines in which the lubricating oil covers the cylinder wall in relatively abundant quantities and circulates continuously between the piston and the crankcase; the oil, which is used in quantities just sufficient for the lubrication of cylinder and piston, must also keep the cylinder wall and piston wall, and also the piston springs, clean and protect them from corrosion by acids formed by the combustion of the fuel, and it must do this while it is largely lost through combustion.

The difficulties are further due to the fact that these engines, which are usually used for the operation of ships and are built for large power outputs, are run with cheap fuels that have a high sulfur content and leave a considerable amount of residue after combustion.

A solution to these problems has already been found by

by using water-in-oil emulsions containing salts

- e.g. calcium acetate - dissolved in the aqueous phase and stabilized with emulsifiers. Furthermore, there are known lubricants which do not consist of emulsions, but of an oil and salts or hydroxides dispersed in it. The properties of such lubricants are considered unsatisfactory, also on the basis of the ever-increasing dimensions of and pressure in engines, particularly when it comes to anti-wear properties.

It has now been found that these disadvantages can be remedied by using a lubricating oil composition which, in addition to a lubricating oil or a mixture of lubricating oils and a dispersed salt and/or hydroxide of an alkaline earth metal, also contains one or more oil-soluble polymers in which carboxyl groups, carboxyl anhydride groups, hydroxyl groups, epoxy groups and/or nitrogenous groups occur, which polymers can be considered as the result of polymerization of olefinically unsaturated compounds.

The invention therefore relates to a lubricating oil composition for cylinder liners of engines with separate cylinder and crankshaft lubrication, which, in addition to a lubricating oil or a mixture of lubricating oils and a dispersed salt and/or hydroxide of an alkaline earth metal, also contains one or more oil-soluble polymers in which carboxyl groups , carboxyl anhydride groups, hydroxyl groups, apoxy groups and/or nitrogen-containing groups occur, which polymers are produced by polymerization of olefinically unsaturated

connections.

The term "polar groups" shall here be understood to

include only carboxyl groups, carboxylic anhydride groups, hydroxyl groups, epoxy groups and nitrogen-containing groups.

The term polymers shall here be understood to include both homopolymers and copolymers.

The combination of dispersed salt or hydroxide and the oil-soluble polymer gives the lubricating oil composition anti-wear properties that are far better than what could be expected on the basis of the combined effect of the individual components. This synergistic effect is even more remarkable in view of the fact that oil-soluble polymers of the present type as such are generally unable to impart anti-wear properties to an oil, if the oil is used for cylinder lubrication in engines with separate cylinder and crankshaft lubrication .

Lubricating oils which can be used as base oils for the lubricating oil composition according to the invention, can e.g. be derived from aromatic, naphthenic or paraffinic crude oils. They can be both. lubricating oil distillates and residual lubricating oils. Mixtures of lubricating oil distillates and residual lubricating oils are also very suitable. Base oils which consist either entirely or to an extent of 90% or more of a lubricating oil distillate or a mixture of lubricating oil distillates are preferred.

The boiling range of the lubricating oil distillates, calculated for atmospheric pressure, is usually between 350 and 550°C.

The viscosity index (Dean and Davis) for these oils varies, depending on the oil and refining technique used, from 0 to 120. As is known, lubricating oil distillates of the aromatic and naphthenic types usually have a lower viscosity index than lubricating oil distillates of the paraffinic type. Lightly refined lubricating oil distillates with a viscosity index of 30 or higher are generally preferred, e.g. a distillate of a naphthenic crude oil extracted with liquid sulfur dioxide and post-treated with earth.

The concentration of the dispersed salt or hydroxide

in the lubricating oil composition can be varied within wide limits and can be adapted to the degree of wear that must be combated. As an example, concentrations from 0.01 to 0.5 equivalent of alkaline earth metal per 100 g of lubricating oil composition. Optionally, higher or lower concentrations can be used.

Alkaline earth metals are to be understood as the metals magnesium.

calcium, strontium and barium. Their hydroxides or salts may be dispersed in oil in any suitable manner.E.g. the hydroxides or salts can be finely divided in a mineral oil using a colloid mill. Another suitable method starts from a solution of the salt or hydroxide in a solvent1 which is mixed or emulsified with oil, optionally with the aid of an emulsifier, after which the solvent is removed from the resulting composition by evaporation or distillation, leaving a dispersion of the salt or the hydroxide in the oil. Such methods are described in British patents 778,468 and 791,413. However, it is preferred to use a composition in which the salt or hydroxide is formed in situ in the presence of a stabilizer. Methods which are suitable for this purpose are e.g. described in British Patents 739,434, 780,058, 786,167, 790,471, 793,608, 795,172, 818,323 and 818,326.

Both an inorganic and an organic salt of an alkaline earth metal can be used. Of the organic salts, the salts of aliphatic carboxylic acids are preferred.

Of the inorganic salts of the alkaline earth metals, the carbonates are very suitable, as they are very easy to obtain in the form of stable dispersions in oil. Examples of the preparation of dispersions of carbonates are mentioned in British patents 786,167, 790,471, 793,608 and 795,172.

When using a stabilizer in the preparation of the dispersions in oil of salts or hydroxides of alkaline earth metals, the quantity normally used in technical practice can be used. This obviously varies with the type of stabilizer used.

When using salts of organic acids as stabilizers, the amount can be expressed as a certain amount of equivalents per equivalent dispersed salt or hydroxide. As an example of an amount of stabilizer expressed with this measure, an amount of 0.1 equivalent stabilizer per equivalent dispersed salt or hydroxide. An amount as small as 0.05 equivalent stabilizer per equivalent dispersed salt or hydroxide is usually sufficient; an amount greater than 0.5 equivalent stabilizer per equivalent salt or hydroxide is rarely necessary.

Examples of salts of organic acids that can be used as stabilizers are the alkaline earth salts of aliphatic and arosatic carboxylic acids and hydroxycarboxylic acids and the alkaline earth esters of aliphatic and non-aromatic sulfonyl rings. Alkaline earth metal salts of aliphatic carboxylic acids obtained in the oil industry as mixtures in the refining of lubricating oil fractions and called naphthenic acids are preferred, although the salts of sulphonic acids, e.g. sulfonic acids produced by sulfonation of aromatic oil fractions, and the salts of alkyl salicylic acids are also very suitable for use as stabilizers.

The concentration of the dispersion of the salt or hydroxide of the alkaline earth metal in the composition according to the invention can be varied within wide limits as previously indicated. First, however, a concentrated dispersion of the salt or hydroxide is preferably prepared in an oil, and the resulting concentrate is used to prepare the composition according to the invention. Concentrates containing 10 - 25% by weight of salt or hydroxide in dispersed form are very suitable.

The oil in which the salts or hydroxides are dispersed when producing a concentrate can be both a residual lubricating oil and a lubricating oil distillate. The concentrate is preferably produced in a lubricating oil distillate. If a lubricating oil distillate or a mixture of lubricating oil distillates is chosen as the base oil for the lubricating oil composition, it is not necessary that the lubricating oil distillate in which the concentrate is produced is the same and can e.g. have a lower viscosity.

The oil-soluble polymers in which "polar groups"

in the meaning of this invention occur, which polymers can be considered as the result of polymerization of olefinically unsaturated compounds, are previously known as lubricating oil additives. Some of these polymers are capable of giving the oil cleaning agent properties.

Production of the polymers can in principle be carried out on

three ways.

First, the polymers can be prepared by direct polymerization of olefinically unsaturated compounds which contain at least partially "polar groups".

The polymers can also be produced by polymerization of olefinically unsaturated compounds that do not contain "polar groups", and by post-treatment of the polymer whereby "polar groups" are introduced into the polymer.

Finally, a polymer obtained by polymerization of olefinically unsaturated compounds which at least partially contain "polar groups" can be subjected to a post-treatment whereby the "polar groups" are converted into "polar groups" of a different type.

As polymers with "polar groups" both polymers can

which contain only "polar groups" of one type, and polymers containing "polar groups" of different types are used.

The polymers which only contain polar groups of one type can be obtained either by homopolymerisation of a monomer with one type of polar group or by copolymerisation of different monomers in which the polar groups are the same. Optionally, monomers that do not contain polar groups may also be present in the mixture to be polymerized. Polymers containing different polar groups can be obtained either by homopolymerization of a monomer in which different polar groups occur, or by copolymerization of different monomers in which the polar groups are different. In this case too, monomers which do not contain polar groups may be present in the mixture to be polymerised.

The olefinically unsaturated monomers containing polar groups can be classified as follows, this classification depending on the type of polar groups they contain: 1. Monomers containing carboxyl groups, such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid and

monododecyl maleate.

2. Monomers containing carboxylic anhydride groups, such as maleic anhydride. 3. Monomers containing hydroxyl groups, such as allyl alcohol, beta-hydroxyethyl methacrylate and pentaerythritol monomethacrylate. 4. Monomers containing epoxy groups, such as glycidyl methacrylate and glycidyl vinyl ether.

5. Monomers in which nitrogenous groups occur,

such as:

(a) Monomers in which the nitrogen occurs in the form of

a nitrile, e.g. acrylonitrile and beta-cyanoethyl acrylate.

(b) Monomers in which the nitrogen occurs in the form of

an amide, e.g. acrylamide and N-octadecyl methacrylamide. (c) Monomers in which the nitrogen occurs as heterocyclically bonded nitrogen, e.g. vinylpyridine and N-vinylpyrroidone.

(d)Monomers in which the nitrogen occurs as a

imide, e.g. laurylmaleimide and N-vinylsuccinimide.

(e) Monomers in which the nitrogen occurs as an amine,

e.g. p-aminostyrene and beta-aminoethyl vinyl ether.

6. Monomers in which different polar groups occur,

such as:

(a) Monomers in which nitrogen is in the form of an imide

occurs in combination with nitrogen in the form of an amine, e.g. the reaction product of maleic anhydride and tetraethylenepentamine.

(b) Monomers in which nitrogen in the form of an amide occurs in combination with nitrogen in the form of an et amine, e.g. N(beta-dimethylaminoethyl)acrylamide. (c) Monomers in which nitrogen in the form of a nitrile occurs in combination with nitrogen in the form of a amine, e.g. N-cyano-N-tert-dodecylaminoethyl acrylate. (d) Monomers in which nitrogen in the form of an amide occurs in combination with hydroxyl, eg N(beta-hydroxyethyl)methacrylamide and N,N'-di(betahydroxyethyl)maleic acid diamide.

Examples of olefinically unsaturated monomers not containing polar groups, which can be copolymerized with monomers containing polar groups, are vinyl esters of saturated monocarboxylic acids, so

such as vinyl palmitate and vinyl stearate; allyl esters of saturated monocarboxylic acids, such as allyl laurate and allyl myristate; alkyl esters of unsaturated monocarboxylic acids, such as lauryl acrylate and stearyl methacrylate; dialkyl esters of unsaturated dicarboxylic acids, such as dilauryfurnarate and distearyl maleate; alkyl vinyl ethers, such as lauryl vinyl ether and stearyl vinyl ether; monoolefins, such as isobutene and styrene; diolefins, such as butadiene and isoprene; alkyl allyl carbonate esters, such as (<C>q<->C^ø) alkyl allyl carbonate esters.

As examples of oil-soluble polymers obtained by direct polymerization of olefinically unsaturated compounds which at least partially contain polar groups in the sense of this invention, the following compounds can be mentioned.

Polymers containing only carboxyl groups as polar groups, such as copolymers of unsaturated monocarboxylic acids with alkyl esters of unsaturated monocarboxylic acids or with monoolefins.

Polymers containing only carboxylic anhydride groups

as polar groups, then as copolymers of anhydrides of unsatd

dicarboxylic acids with alkyl esters of unsaturated monocarboxylic acids or with vinyl esters of saturated monocarboxylic acids.

Polymers containing only hydroxyl groups as polar groups, such as copolymers of unsaturated alcohols, hydroxyalkyl esters of unsaturated monocarboxylic acids and partial esters of polyalcohols and unsaturated monocarboxylic acids with alkyl esters of unsaturated monocarboxylic acids.

Polymers containing only epoxy groups as polar groups, such as copolymers of glycidyl esters of unsaturated monocarboxylic acids with alkyl esters of unsaturated monocarboxylic acids.

Polymers in which only nitrogen-containing groups of one and

the same type occurs as polar groups, such as copolymers of unsaturated amides, nitriles, amines, imides and heterocyclic compounds with alkyl esters of unsaturated monocarboxylic acids.

Polymers containing both carboxyl groups and nitrogen-containing groups as polar groups, such as copolymers of unsaturated monocarboxylic acids with amides of unsaturated monocarboxylic acids and with monomers not containing polar groups.

Polymers containing both carboxyl groups and hydroxyl groups as polar groups, such as copolymers of unsaturated monocarboxylic acids with hydroxyalkyl esters of unsaturated monocarboxylic acids or with partial esters of polyalcohols and unsaturated monocarboxylic acids and with monomers not containing polar groups.

Polymers containing both hydroxyl groups and amide

groups as polar groups, such as copolymers of N-hydroxyalkyl-substituted amides of unsaturated monocarboxylic acids with monomers not containing polar groups.

Polymers containing both amide groups and amino groups as polar groups, such as copolymers of N-amino-alkyl substituted amides of unsaturated monocarboxylic acids with alkyl esters of unsaturated monocarboxylic acids and copolymers of unsaturated amides with unsaturated amines and with monomers not containing polar groups.

Polymers in which both amide groups and groups contain

holding heterocyclically bound nitrogen occur as polar groups, such as copolymers of unsaturated amides with vinylpyridine or derivatives thereof and with monomers not containing polar groups.

Polymers containing both imide groups and amino groups

as polar groups, then as copolymers of imides of unsatd

dicarboxylic acid anhydrides and polyalkylene polyamines with alkyl esters of unsaturated monocarboxylic acids.

Polymers containing both nitrile groups and amino groups as polar groups, such as copolymers of N-cyano-N-alkylamino alkyl esters of unsaturated monocarboxylic acids with alkyl esters of unsaturated monocarboxylic acids.

As examples of oil-soluble polymers obtained by polymerization of olefinically unsaturated compounds not containing polar groups, which polymers are subjected to a post-treatment whereby polar groups are introduced into the polymer, the following compounds can be mentioned: Homopolymers of alkyl esters of unsaturated monocarboxylic acids or copolymers of alkyl esters of unsaturated monocarboxylic acids of various kinds or with monoolefins, which polymers are subjected to aminolysis with a mono- or polyamine, whereby the non-polar ester groups are converted into polar amide groups.

Homopolymers of vinyl esters of saturated monocarboxylic acids or copolymers of vinyl esters of saturated monocarboxylic acids with monoolefins, which polymers are subjected to hydrolysis, whereby the non-polar ester groups are converted into polar hydroxyl groups.

Homopolymers of vinyl esters of saturated monocarboxylic acids or copolymers of vinyl esters of saturated monocarboxylic acids with monoolefins, which polymers are subjected to hydrolysis and then treated with an alkyl isocyanate, whereby the non-polar ester groups are converted into polar carbamate groups via polar hydroxyl groups.

Homopolymers of unsaturated aldehydes and alkyl vinyl ketones, which polymers are treated with a primary amine, whereby the non-polar carbonyl groups are converted into polar imine groups.

Copolymers of unsaturated aldehydes and alkyl esters of unsaturated monocarboxylic acids, which polymers are treated with hydroxylamine, whereby the non-polar carbonyl groups are converted into polar oxime groups.

Homopolymers of vinyl esters of saturated monocarboxylic acids, which polymers are partially hydrolysed and then treated with acrylonitrile, whereby non-polar ester groups are converted into polar cyanoethyl ether groups via polar hydroxyl groups.

As examples of oil-soluble polymers obtained by polymerization of olefinically unsaturated compounds which at least partially contain polar groups, which polymers are subjected to a post-treatment with the result that the polar groups are converted into polar groups of a different type, the following compounds can be mentioned : Copolymers of anhydrides of unsaturated dicarboxylic acids with monoolefins or other monomers without polar groups,

which polymers are treated with a primary amine, whereby the polar carboxylic anhydride groups are converted into polar imide groups.

Copolymers of unsaturated monocarboxylic acids with alkyl esters of unsaturated monocarboxylic acids, which polymers are ethoxylated with ethylene oxide, whereby the polar carboxyl groups are converted into polar hydroxyethyl groups.

Usually it is sufficient that one oil-soluble polymer is incorporated into the lubricating oil composition. Optionally, two or more oil-soluble polymers can be incorporated into the lubricating oil composition. The following polymers are preferred.

Copolymers of heterocyclic, nitrogen-containing, olefinically unsaturated compounds with alkyl esters of unsaturated monocarboxylic acids, preferably copolymers of vinyl-substituted pyrrolidones or vinyl-substituted pyridines with alkyl esters of unsaturated monocarboxylic acids, in particular a copolymer of N-vinyl pyrrolidone with a mixture of alkyl methacrylates with from 4 to 18 carbon atoms in the alkyl group, and a copolymer of 2-methyl-5-vinylpyridine with a mixture of methyl, lauryl and stearyl methacrylate.

Copolymers of unsaturated monocarboxylic acids with alkyl esters of unsaturated monocarboxylic acids, which polymers are treated with alkylene oxide, in particular a copolymer of methacrylic acid with iauryl methacrylate and stearyl methacrylate, which polymer is treated with ethylene oxide.

The concentration used of the oil-soluble polymers can be used within a wide range, depending on the nature, structure and molecular weight of the polymer to be used, and on the anti-wear effect to be achieved. In some cases, as little as 0.1 wt.-9C, calculated according to the lubricating oil composition, will be sufficient to achieve the synergistic anti-wear effect. In most cases, an amount of 10% by weight is sufficient. Higher and lower concentrations than those mentioned above can also be used in some cases.

The oil-soluble polymers are used as a component

of the lubricating oil composition. It is not necessary that they have lubricating oil properties themselves, and it is therefore also not necessary that their viscosity lies within the viscosity range that is common for lubricating oils. One can therefore use oil-soluble polymers with varying viscosity, and therefore with varying molecular weight.

Particularly good compositions according to the invention can be prepared from a lubricating oil distillate refined with liquid sulfur dioxide and post-treated with earth, with a viscosity

index of from 30 to 60 and a viscosity at 50°C of from 60 to 75 cS, one concentrated dispersion of calcium carbonate stabilized with calcium naphthenate in an amount of from 0.08 to 0.12 equivalent calcium naphthenate per equivalent dispersed calcium carbonate in a mineral oil with a viscosity at 50°C of from 7.0 to 21 cS, and as oil-soluble polymer either a copolymer of acrylates or methacrylates with vinyl-substituted pyrrolidones or vinyl-substituted pyridines or an ethoxylated copolymer of acrylic acid or methacrylic acid with acrylates or methacrylates.

The invention shall be illustrated in more detail by means of the

the following examples.

EXAMPLE .1

Base oil (naphthenic lubricating oil distillate with a

viscosity index of 45 and a viscosity

at 50°C of 68 cS and at 98.9°C of 10.2 cS) ........ 65.2% by weight Copolymer of lauryl methacrylate with stearyl methacrylate

and methacrylic acid in a molar ratio of 5:5:4, i

in which polymer the carboxyl groups have been converted to hydroxyethyl groups by means of ethylene-

oxide; average molecular weight of

the polymer 1,200,000 0.8% by weight Concentrate in lubricating oil distillates of dispersed

calcium carbonate stabilized with 0.10

equivalent calcium naphthenate; Ca content

7.35 weight -% 34.0 weight -%

EXAMPLE II

Base oil. from example I.... 65.2% by weight Copolymer of a mixture of alkyl methacrylates with

from 4 to 18 carbon atoms in the alkyl group

with N-vinylpyrrolidone in a molar ratio of

about. 7.5:1; average molecular weight for

the polymer 800,000 0.8% by weight Concentrate of dispersed calcium carbonate which

in example 1 34.0% by weight

EXAMPLE III

Base oil as in example 1 65.2% by weight Copolymer of methyl methacrylate, lauryl methacrylate

and stearyl methacrylate with 2-methyl-5-vinyl-

pyridine in a weight ratio of 16.0:49.7:29.3:5.0;

Average molecular weight of the polymer

800,000 0.8% by weight Concentrate of dispersed calcium salt as in ex. 1 34.0% by weight

COMPARISON OIL

Base oil (naphthenic residual lubricating oil with a viscosity

at 98.9°C of 16.12 cS) 66% by weight Concentrate of dispersed calcium carbonate as in

e.g. 1 34 t weight-%

The oils were tested in a "Werkspoor DM 1" engine. This is

a single-cylinder four-stroke engine, bore x stroke 320 x 450 mm. This engine has separate lubrication of the cylinder and crankshaft. The duration of the test was 13 hours at a load of 50 hp and a speed of

250 revolutions per my.

The cylinder was lubricated with the above-mentioned oils. The fuel was a residual oil with a sulfur content of 3.5%.

The test results are given in the following table.

WERKSPOOR 13-HOUR TRIAL

These examples illustrate the favorable anti-wear effect of an oil according to the invention compared to the effect of a comparison oil with the same metal content as the oil according to the invention.

Claims (3)

1. Lubricating oil composition for cylinder lubrication of engines with separate cylinder and crankshaft lubrication, containing a salt and/or hydroxide of an alkaline earth metal dispersed using a salt of an organic acid as stabilizer, characterized in that in addition to a lubricating oil or a mixture of lubricating oil, it also contains one or more oil-soluble polymers in which carboxyl groups, carboxyl anhydride groups, hydroxyl groups, epoxy groups and/or nitrogen-containing groups occur, which polymers are produced by polymerization of olefinically unsaturated compounds. 2. Lubricating oil composition as stated in claim 1, characterized in that the content of dispersed salt or hydroxide is from 0.01 to 0.5 equivalents of alkaline earth metal per 100 g of lubricating oil composition. 3. Lubricating oil composition as stated in claims 1-2, characterized in that the dispersion is prepared with a salt of an organic acid as a stabilizer in an amount of from 0.05 to 0.5 equivalent stabilizer per equivalent dispersed salt or hydroxide.