NO122141B - - Google Patents

Description

Lubricant.

The present invention relates to a lubricant.

Heavy oils are burned in large ship engines. These oils often contain relatively large amounts of sulphur. During combustion, the sulfur can form sulfur dioxide and/or sulfur trioxide as acidic combustion products. These products often, alone or with other combustion products, cause engine corrosion problems. In order to avoid or reduce these problems, basic naphthenates of metals from group II of the periodic system have been added to the lubricating oils so that the added substances can be available for neutralization of acidic combustion products. A lubricant containing such a naphthenate has now been provided, and the new lubricant exhibits improved anti-rust properties, improved thermal stability and basicity.

According to the present invention, the lubricant comprises a hydrocarbon lubricating oil, at least one oil-soluble basic salt of at least one naphthenic acid and at least one metal from the periodic system group II with an atomic number of 12 to 56, and at least one oil-soluble basic salt of at least one aromatic carboxylic acid and at least one metal from group II of the periodic table with an atomic number of 12 to 56. Such a product would be acceptable on board ships as a lubricant for auxiliary engines and the main engine. This is advantageous because until now special lubricants have been used for the main engine and auxiliary engines.

The basic salt or salts of at least one naphthenic acid and the basic salt or salts of at least one aromatic carboxylic acid should preferably be present in amounts to give the lubricant portion a total electromeric base number of 5 to 12 (preferably 6 to 10, especially in the main 8) mgKOH/g. The total electromeric base number (for brevity called the TEBT number) is in the present description determined by the method specified by the American Society for Testing Materials (abbreviated ASTM) method D664-58 or the Institute of Petroleum method 177/64.

The English abbreviation for total electromeric base number

is TBNE, total base number electromeric.

The hydrocarbon lubricating oil can be of mineral or synthetic origin. It can be a single oil or a mixture. An example of a mixture is a mixture of mineral lubricating oils, e.g. a mixture of a distillate lubricating oil with a light oil. Another example is a mixture of a mineral lubricating oil with a synthetic hydrocarbon lubricating oil. The mineral lubricating oil can essentially be paraffinic and/or naphthenic, but it can contain significant amounts of aromatic hydrocarbons. Mineral lubricating oils are suitably produced from highly paraffinic crude oils. In this case, distillation and/or dewaxing may be sufficient to provide mineral lubricating oils. Chemical or selective solvent treatment can also be used, but this is preferably reduced to a minimum for economic reasons. Blended crudes, or highly aromatic crudes, containing paraffinic hydrocarbons can also be refined to yield satisfactory mineral lubricating oils. Such refining may include separation of distillate fractions with appropriate boiling point ranges, solvent extraction of fractions with selective solvents (e.g. furfural or phenol) to obtain raffinate fractions, dewaxing of the raffinate fractions and chemical treatment of the dewaxed raffinate fractions (e.g. .e.g. by means of sulfuric acid. An example of a suitable hydrocarbon lubricating oil of synthetic origin is a polyolefin, e.g. a polyisobutylene. The viscosity of the hydrocarbon lubricating oil can vary within wide limits, so that the finished lubricant enters under f .eg SAE classes 5W, 10W, 20W, 20, 30, 40, 50, 60 or 70. (SAE stands for Society of Automotive Engineers).

The basic salt or salts of naphthenic acids are suitably present in an amount to give a total electromeric base number of 1.5 to 3 mgKOH/g for 1% by weight of them in the lubricating oil. Preferably, 0.5 to 3 weight percent, based on the lubricant, of the basic salt or salts of at least one naphthenic acid should be present. The naphthenic acids may have average molecular weights of 150 to 750, although lower or higher molecular weights are possible. The excess of basicity (see below) of the basic salts of the naphthenic acids compared to the neutral salts may be over 400%, preferably over 600%, e.g. 800 or more up to the achievable limit. Suitable salts are of barium, calcium, magnesium, strontium or zinc. Preferred salts are calcium salts.

The excess basicity of the basic salts of the naphthenic acids and the basic salts of aromatic carboxylic acids is obtained using the formula:

In this formula, M is the number of Group II metal equivalents, and E

is the number of equivalents of naphthenic acid or aromatic carboxylic acid per 100 g of basic salt. For the naphthenic acid salt or salts must

M and E give a total electromeric base number of 1 to 1.5 mgKOH/g for

1 percent by weight of them in the lubricating oil. For the aromatic carboxylic acid salt or salts, M and E must give a total electromeric base number of 1 to 1.5 mgKOH/g for 1% by weight of them in the lubricating oil.

The basic salt or salts of aromatic carboxylic acids should conveniently be present in an amount of 1 to 6 percent by weight based on the lubricant. Suitable salts are of barium, calcium, strontium or zinc. The preferred salts are calcium salts. The aromatic carboxylic acids can be hydrocarbon-substituted benzoic acids, salicylic acids, dihydroxybenzoic acid, anthranilic acid or naphthalene carboxylic acids. Examples of these are C3-C22-alkylbenzoic acid, C3-C22~ alkylsalicylic acid and C3-C22-alkylnaphthalene carboxylic acids, e.g. lauryl salicylic acid, stearyl salicylic acids or mixtures of C 8 -C 30 alkyl salicylic acids. Preferred acids are C1-C12- or C14-C22 alkylsalicylic acids. These acids are suitably used to give mixtures

of basic salts of C14-<C>18- or C14-C22-monoalkyl- and -dialkyl-salicylic acids. A mixture of basic calcium salts of C^4-C^8-mono-

in

alkyl and dialkyl salicylic acids are particularly preferred. This mixture is hereinafter referred to as salt A. Accordingly, it has an excess basicity of 50%, 200% or 600%.

Preferably, a lubricant according to the invention should also contain 0.01 to 2.0 (preferably 0.05 to 1.0) percent by weight

of at least one antioxidant. One class of suitable antioxidants are metal thiophosphates, such as e.g. calcium or zinc dialkyldithiophosphates, especially those where the alkyl groups are amyl and/or butyl. Another class consists of alkylphenols, e.g. di- and tri-alkylphenols (preferably 2,6-di-tertiarybutyl-4-methylphenol) and alkyl bisphenols (e.g. bis-(3,5-di-tertiarybutyl-4-hydroxyphenyl)-methane). A third class is arylamines, such as e.g. phenylalphanaphthylamine or phenylbetanaphthylamine. Antioxidants from these classes can also be used together if desired.

Other additives can be added to a lubricant according to the invention. Examples of such are anti-scuffing agents (e.g. phosphorus-containing esters), anti-foaming agents (e.g. silicone polymers), viscosity index improvers (e.g. polymeric acrylic esters), extreme pressure additives (e.g. dibenzyl disulphide) , rust inhibitors (e.g. condensation products of maleic anhydride and long-chain olefins), oil-free agents (e.g. acid-free tallow) and surfactants (e.g. peroxidized aromatic extracts).

The invention shall now be clarified by the following compositions:

Antirust test; This was carried out in accordance with ASTM method D 665,

but a 20% saturated saline solution was used

as a corrosive medium.

Demulsibility test; The test oil was stirred with 10 volume percent water

in an ASTM Method D665 apparatus at 60°C, and the oil let

it is then allowed to settle under the influence of gravity at this temperature. Samples were taken after 2 hours and 16 hours from the top layer and

the water content of the samples was determined. Oxidation stability test; This was a SCOT test at 160°C using soluble iron catalyst.

From table i, it will be seen that by using basic caffeine alkyl salicylates with basic calcium naphthenates, a lubricating oil containing basic calcium naphthenates will have better anti-rust properties, better de-emulsification properties and better oxidation stability properties.

From table 2 it will be seen that the total electromeric base numbers for compositions C, E and F are greater than the total electromeric base numbers for compositions A, B and D. Compositions B and D . thus corresponds to a TEBT figure of 1.25 mgKOH/g per 1 weight percent basic calcium alkyl salicylates and composition A corresponds to a TEBT number of 2 mg KOH/g per 1 vol% basic calcium naphthenates, showing that the total TEBT numbers for compositions C, E and F would have been 7.75 mgKOH/g, 7.675 mgKOH/g and 7.8 mgKOH/g instead of the determined 7.8 mgKOH/g , 8.0 mgKOH/g and 8.0 mgKOH/g.

Claims (10)

1. Lubricant comprising a major amount of a hydrocarbon lubricating oil and minor amounts of oil-soluble basic salts of organic acids and metals from the periodic system group II with an atomic number of 12 to 56, characterized in that it contains 0.1 - 20% by weight, preferably 0.1 - 10% by weight of a) an oil-soluble basic salt of a naphthenic acid and said metal, known in and of itself as a lubricating oil additive, and b) an oil- soluble basic salt of an aromatic carboxylic acid and said metal, known per se as a lubricating oil additive. 2. Lubricating oil as stated in claim 1, characterized in that the lubricant has a total electromeric base number of 5 to 12 mgK0H/g. 3. Lubricant as stated in claims 1-2, characterized in that the basic salt or salts of at least one naphthenic acid are present to give a total electromeric base number of 1.5 to 3 mgK0H/g for 1 percent by weight of them in the lubricating oil . 4. Lubricant as stated in claims 1-3, characterized in that it contains 0.5 to 3 percent by weight, based on the lubricant, of the basic salt or salts of at least one naphthenic acid. 5. Lubricant as stated in claims 1-3, characterized in that the basic salt or salts of at least one naphthenic acid has an excess basicity of over 400%. 6. Lubricant as specified in claims 1-5, characterized in that the salt or salts of at least one naphthenic acid are calcium salts. 7. Lubricant as specified in claims 1-6, characterized in that it contains 1 to 6 percent by weight, based on the lubricant, of the basic salt or salts of at least one aromatic carboxylic acid. 8. Lubricant as specified in claim 7, characterized in that the basic salt or salts of at least one aromatic carboxylic acid are basic calcium salts of C,„-C,0- or x 4 lb C14-C22<-m>onoalkyl- and dialkyl-salicylic acids.. 9. Lubricant as stated in claims 1-8, characterized in that it contains at least one metal thiophosphate. 10. Lubricant as stated in claim 9, characterized in that it contains a zinc dialkyldithiophosphate.