Mannich Base Composition

This invention relates to novel Mannich bases and their uses as lubricating oil additives.

For a variety of reasons, higher sulfur content fuels are now being used, particularly in marine engines. This high sulfur content leads to the formation in the presence of oxygen of corrosive sulfur acids, particularly sulfuric acid. To prevent damage to the engine from these sulfur acids, they must be neutralized with a basic material. This basic material is ordinarily an additive in the oil used to lubricate the engine. As higher sulfur content fuels are used, a greater and greater reservoir of alkalinity must be included in the lubricating oil to neutralize the acids. However, using conventional additives, such as calcium phenates, an increase in the amount of additive leads to an increase in ash formation, which is detrimental to the engine.

It is an object of this invention to provide a lubricating additive which is effective in neutralizing sulfur acids. It is a further object of this invention to provide a lubricating oil additive which is also an effective dispersant. It is an additional object of this invention to provide an additive which can neutralize large quantities of these acids with lower resultant ash formation than for conventional additives.

U.S. Pat. No. 3,036,003 teaches the use in lubricating oils of a combination of a detergent amount of a basic alkaline earth metal petroleum sulfonate and the condensation product of an alkyl-substituted phenol in which the alkyl group contains from 4 to 20 carbon atoms, formaldehyde and an alkylene polyamine and the alkaline earth metal salts thereof. The molar ratio of the reactants of this condensation product are 0.5-2 mols of each of the phenol and formaldehyde for each nitrogen atom present in the polyamine.

U.S. Pat. No. 3,649,229 teaches the use of high molecular weight Mannich reaction products as additives for hydrocarbon fuels. The condensation product is prepared by reacting a high molecular weight alkylhydroxyaromatic compound having a molecular weight of from about 600 to 3000 with an amine and an aldehyde. The molar ratio of the reactants is 1:0.1-10 to 0.1-10. A specific example teaches the preparation of a Mannich condensation product from polypropylphenol of 900 molecular weight with diethylene triamine and paraformaldehyde in the ratio 1:0.75-1.

The Mannich bases and the alkaline earth metal salts thereof of this invention are prepared from formaldehyde, a polyamine and a phenolic mixture consisting of (1) from 95 to 30% phenol alkylated with a propylene tetramer and (2) from 5 to 70% phenol alkylated with a straight-chain alpha-olefin of from 16 to about 28 carbon atoms or alpha-olefin mixtures wherein the alpha-olefins are of from 16 to about 28 carbon atoms. These Mannich bases are useful as lubricating oil additives.

Component 1 of the phenolic mixture is prepared by alkylating a phenol with propylene tetramer. It is also known in the art as tetrapropenyl phenol or dodecylphenol.

Component 2 of the phenolic mixture can be a phenol alkylated with a straight-chain alpha-olefin of from 16 to about 28 carbon atoms, or a phenol which has been alkylated with a mixture of alpha-olefins of from 16 to about 28 carbon atoms in each each alpha-olefin. It is important for the effectiveness of the additive that at least one olefin alkylating group contain at least 16 carbon atoms. Thus, a phenol alkylated with, for example, two groups containing 9 carbon atoms each would not, when used to prepare additives of this invention, provide adequate performance, especially from the standpoint of forming a product with a viscosity suitable for use in commercial operations.

Mixtures of alpha-olefins, available on a commercial basis, are suitable for alkylation of the phenols of the invention. These mixtures normally contain predominantly C.sub.20 to C.sub.28 olefins but may also contain a small proportion of olefins having less than 16 or more than 28 carbon atoms. A representative olefin mixture is Dailen 208, manufactured by Mitubishi.

Preferred olefins are those which are a mixture of about 60-80 mol percent C.sub.18 -C.sub.28 alpha-olefins and about 40 to 20 mol percent C.sub.24 -C.sub.28 alpha-olefins.

The percent of each phenolic compound from group 1 and group 2 used in the phenolic mixture is based on the phenol equivalents (as calculated from the measured hydroxyl number) of each.

Formaldehyde, or a formaldehyde precursor, such as paraformaldehyde, is used to prepare the condensation product of this invention.

The polyamines used in preparing the novel compositions of this invention are the well-known ethylene amines, specifically ethylene diamine, diethylene triamine, triethylene tetraamine, tetraethylene pentamine, and pentaethylene hexamine. These compounds are usually prepared by the reaction of an alkylene chloride with ammonia. This reaction yeilds a somewhat complex mixture of alkylene amines, including some cyclic condensation product. These mixtures are also included within the scope of the term "polyamine".

Also included within the scope of the term "polyamine" are those amines prepared by reaction of acrylonitrile with an ethylene amine as described above, or with an amine of the formula H.sub.2 N--(CH.sub.2)xNH.sub.2 where x is 3-6, followed by reduction of the resultant intermediate. For example, the product prepared from ethylene diamine and acrylonitrile would be H.sub.2 N--(CH.sub.2).sub.3 NH--(CH.sub.2).sub.2 NH--(CH.sub.2).sub.3 NH.sub.2. Preferred polyamine, for use in this invention, is diethylene triamine.

The Mannich bases of this invention can be prepared by conventional methods as described in the art. It is preferred to prepare the Mannich bases by reacting 1 mol of the phenolic mixture with 0.5-0.85 mol formaldehyde and at least 0.3 mol of polyamine. The reaction is carried out at a temperature of 25.degree.-140.degree. C., preferably 25.degree.-130.degree. C., and in the presence of a suitable solvent, such as benzene or toluene, which can be recovered from the reaction product. If desired, the reaction may be carried out in a mineral lubricating oil and the condensation product is recovered as a lubricating oil concentrate.

Alkaline earth metal salts of the Mannich bases of this invention are particularly useful as lubricating oil additives. Preferred alkaline earth metal salts are calcium and magnesium.

The alkaline earth metal salts of the Mannich bases are prepared using conventional methods, for example, by treating the Mannich base with an alkaline earth metal hydroxide, such as calcium hydroxide or magnesium methoxide in the presence of a promotor, such as water, ethylene glycol, 1,3-propane diol, 1,4-butane diol, diethylene glycol, butyl cellosolve, propylene glycol, 1,3-butylene glycol, methylcarbitol, diethanol amine, N-methyldiethanol amine, dimethyl formamide, N-methyl acetamide, or dimethyl acetamide. Preferred promotors are water, ethylene glycol and dimethyl acetamide. Most preferred is ethylene glycol. The reaction is carried out at 100.degree.-175.degree. C. After the reaction is completed, the product is stripped at a higher temperature, such as 175.degree.-202.degree. C. and at reduced pressure, for example 20 mm Hg, to remove any unreacted low-molecular-weight polyamines, such as ethylene diamine and diethylene triamine, and other volatile components.

The Mannich bases and the alkaline earth metal salts thereof of this invention provide a high alkalinity value. The alkaline earth metal salts provide a particularly high alkalinity value at a lower ash content than is present in conventional dispersants and acid neutralizers used in lubricating oil additives.

Alkalinity value is one method of specifying the degree of overbasing of the phenate portion of Mannich base. It is also a measure of the acid-neutralizing properties of the compound. The method for determining the alkalinity value of a composition is set forth in ASTM Method D-2896. Briefly, the alkalinity value is the total base number given as milligrams of potassium hydroxide per gram of sample. It is the quantity of perchloric acid expressed in terms of equivalent number of milligrams of potassium hydroxide that is required to neutralize all basic constituents present in one gram of sample. For example, if a composition has the same acid-neutralizing capacity per gram as 10 mg of potassium hydroxide, the composition is given an alkalinity value of 10. The lower limit of alkalinity value is 0 for a neutral phenate. Values of 200-260 are especially desirable for use in lubricants which are exposed to the decomposition products of sulfur-containing diesel fuels. Further, the high alkalinity value for the products of this invention is achieved with a lower amount of ash than would be present if conventional metal phenate additives were used.

Most importantly, the Mannich bases of this invention have a sufficiently low viscosity to enable their preparation using conventional processing equipment, the products have a viscosity of from about 1000 to 3000 Saybolt Universal Seconds (SUS) at 99.degree. C.

The lubricant composition is prepared by admixing through conventional admixing techniques the appropriate amount of the Mannich base or the alkaline earth metal salt of the Mannich base with a lubricating oil. The selection of the particular base oil depends on the contemplated application of the lubricant and the presence of other additives. Generally, the amount of the Mannich base or the alkaline earth metal salt thereof used in the lubricating oil will vary from 0.1 to 40% by weight, and preferably from 3 to 35% by weight.

The lubricating oil which may be used in this invention includes a wide variety of hydrocarbon oils, such as naphthenic bases, paraffin bases and mixed base oils. The lubricating oils may be used individually or in combination and generally have a viscosity which ranges from 50 to 5000 SUS and usually from 100 to 1500 SUS at 38.degree. C.

In many instances, it may be advantageous to form concentrates of the Mannich base or the alkaline earth metal salts thereof of this invention within a carrier liquid. These concentrates provide a convenient method of handling and transporting the additives of this invention before their subsequent dilution and use. The concentration of the Mannich base or the alkaline earth metal salt of the Mannich base within the concentrates may vary from 85 to 40% by weight, although it is preferred to maintain the concentration between about 50 and 70% by weight.

As desired, other additives may be included in the lubricating oil compositions of this invention. These additives include antioxidants or oxidation inhibitors, dispersants, rust inhibitors, anticorrosive agents, and so forth. Of particular interest are overbased sulfonates. Other types of lubricating oil additives which may be employed include antifoam agents, stabilizers, antistain agents, tackiness agents, antichatter agents, dropping point improvers, antisquawk agents, extreme pressure agents, odor control agents and the like.

The following examples are presented to illustrate the practice of specific embodiments of this invention and should not be interpreted as limitations on the scope of the invention.

To a 2-liter, 3-necked flask is added 283 g (0.62 mol) of phenol alkylated with a mixture of olefins comprising about 70% alpha-olefins containing from 18 to 28 carbon atoms and about 30% alpha-olefins containing from 24 to 28 carbon atoms, 91 g (0.32 mol) of phenol alkylated with propylene tetramer, 52 g (0.5 mol) diethylene triamine and 24 g paraformaldehyde (0.75 mol formaldehyde). The mixture is heated to 130.degree. C. over a period of 1 hour and then held at 125.degree.-130.degree. C. for an additional hour. To the mixture is added 62 g (1.0 mol) ethylene glycol. The mixture is stirred for 10 minutes and then 37 g (0.5 mol) calcium hydroxide is added. The mixture is heated to 175.degree. C. over a 1-hour period and then held at this temperature for an additional hour. The mixture is then stripped to 175.degree. C. bottoms at 20 mm Hg to yield a product weighing 442 g. To this is added 24 g diluent oil. The mixture is filtered through diatomaceous earth to yield a product having an alkalinity value of 220 and containing 3.39% calcium and 3.11% nitrogen. The viscosity of the product at 210.degree. F. is 1983 SUS.

To a 3-liter flask is added 150 g diluent oil, 550 g (1.2 mol) phenol alkylated with a mixture of 70 mol percent alpha-olefins of 18 to 28 carbon atoms and about 30 mol percent alpha-olefins of 24 to 28 carbon atoms, 450 g (1.59 mols) phenol alkylated with propylene tetramer and 155 g (1.5 mols) diethylene triamine. The reaction mixture is stirred at 62.degree. C. and 72 g paraformaldehyde (2.25 mols formaldehyde) is added. The mixture is heated to 130.degree. C. over a period of 1 hour and then held for an additional hour at this temperature. Water is removed under vacuum and then 186 g (3 mols) ethylene glycol is added. After stirring the mixture for 10 minutes, 111 g (1.5 mols) calcium hydroxide is added. The mixture is heated to 175.degree. C. over a period of 1 hour and held for 1/2 hour at 178.degree.-180.degree. C. The mixture is then stripped to 176.degree. C. bottoms at 20 mm Hg. To the crude product weighing 1341 g is added 150 g diluent oil to yield 1491 g of an 80% concentrate. This concentrate is filtered through diatomaceous earth to yield a product having an alkalinity value of 210. The product contains 3.32% calcium and 3.08% nitrogen and has a viscosity of 1019 SUS at 210.degree. F.

To a 3-liter flask is added 150 g diluent oil, 412 g (0.9 mol) of phenol alkylated with a mixture of about 70 mol percent alpha-olefins containing from 18 to 28 carbon atoms and 30 mol percent olefins containing 24 to 28 carbon atoms, and 525 g (1.86 mols) of phenol alkylated with propylene tetramer. The reaction mixture is stirred and 155 g (1.5 mols) of diethylene triamine and 72 g paraformaldehyde (2.25 mols formaldehyde) are added. The mixture is heated to 125.degree.-130.degree. C. over a period of 1 hour and then held for an additional 1 hour at this temperature. 186 g ethylene glycol is added with stirring at 122.degree. C. and then 111 g (1.5 mols) of calcium hydroxide is added. The mixture is heated to 175.degree. C. over a 1-hour period and held for an additional hour at 175.degree.-178.degree. C. The mixture is stripped to 175.degree. C. bottoms at 20 mm Hg to yield 1282 g of product. 135 g diluent oil is added. The product is heated to 150.degree. C. and then filtered through diatomaceous earth to yield a product having an alkalinity value of 231. The product contains 3.53% calcium and 3.36% nitrogen and has a viscosity of 3306 SUS at 210.degree. F.

To a 3-liter flask is added 150 g diluent oil, 345 g (0.75 mol) phenol alkylated with a mixture of 70% olefins having 18 to 28 carbon atoms and 30% alpha-olefins of 24 to 28 carbon atoms, and 600 g (2.12 mols) phenol alkylated with propylene tetramer, 156 g (1.5 mols) diethylene triamine and 72 g paraformaldehyde (2.25 mols formaldehyde). The reaction mixture is heated to 125.degree. C. over a period of 1 hour and held for an additional hour at 125.degree.-132.degree. C. Ethylene glycol (186 g, 3 mols) is then added to the mixture at 100.degree. C. After stirring for 10 minutes, 111 g (1.5 mols) calcium hydroxide is added. The mixture is heated to 175.degree. C. over a period of 1 hour and then held at 175.degree.-178.degree. C. for an additional hour. The mixture is stripped to 175.degree. C. bottoms at 20 mm Hg. To the crude product, weighing 1292 g, is added 135 g diluent oil. The mixture is filtered through diatomaceous earth to yield a product having an alkalinity value of 230. The product contains 3.72% calcium, 3.35% nitrogen and has a viscosity at 210.degree. F. of 2738 SUS.

To a 10-gallon reactor is added 1923 g diluent oil, 8435 g (30.8 mols) of phenol alkylated with propylene tetramer, 3565 g (7.75 mols) of phenol alkylated with a mixture of 70% alpha-olefins containing 18 to 28 carbon atoms and 30% of a mixture of alpha-olefins containing 24 to 28 carbon atoms. To the mixture is added 2000 g (19.4 mols) diethylene triamine. The reaction mixture is stirred, heated to 54.degree. C. and then 974 g paraformaldehyde (29.5 mols formaldehyde) is added. The mixture is heated over a period of 1 hour to 124.degree.-127.degree. C. and then held for 1 hour at this temperature. 2385 g (38.5 mols) ethylene glycol is added at 96.degree.-99.degree. C. After stirring to mix thoroughly, 1423 g (19.2 mols) calcium hydroxide is added. The reaction mixture is heated to 180.degree.-182.degree. C. over a period of 1 hour and held at this temperature for an additional hour. The mixture is then stripped at this temperature while applying vacuum to 20 mm Hg. The reaction mixture is then filtered through diatomaceous earth at 121.degree.-149.degree. C. to yield 14,280 g product having an alkalinity value of 222. The product contains 3.68% calcium and 3.19% nitrogen and has a viscosity of 1604 SUS at 210.degree. F.

To a 3-liter flask is added 152 g diluent oil, 172 g (0.37 mol) phenol alkylated with a mixture of 70% alpha-olefins of 18 to 28 carbon atoms and 30% alpha-olefins of 24 to 28 carbon atoms, and 675 g (2.39 mols) phenol alkylated with propylene tetramer and 156 g (1.5 mols) diethylene triamine. 72 g paraformaldehyde (2.25 mols formaldehyde) is added. The mixture is heated to 130.degree. C. over a period of 1 hour and held for an additional hour at 125.degree.-130.degree. C. 186 g (3 mols) ethylene glycol is added with stirring at 115.degree. C. and then 111 g (1.5 mols) calcium hydroxide is added. The mixture is heated to 175.degree. C. over a period of 1 hour and held at this temperature for an additional hour. The mixture is then stripped to 175.degree. C. bottoms at 20 mm Hg to yield 1192 g of crude product. To this is added 250 g dilutent oil. The mixture is heated to 150.degree. C. and filtered through diatomaceous earth to yield a product having an alkalinity value of 227. The product contains 3.68% calcium, 3.30% nitrogen, and has a viscosity of 2029 SUS at 210.degree. F.

The compounds of this invention are tested in lubricating oil compositions in the well-known 1-G Caterpillar test. In this test, a single-cylinder diesel engine having a 51/8" bore by 61/2" stroke is operated under the following conditions: timing, .degree.BTDC 8; brake mean effective pressure psi, 141; brake horsepower, 42; BTU's per minute, 5850; speed 1800 rpm; air boost 53" Hg absolute; air temperature in, 255.degree. F. (124.degree. C.); water out, 190.degree. F. (88.degree. C.); and sulfur in fuel, 0.4% by weight. At the end of each 12 hours of operation, sufficient oil is drained from the crankcase to allow addition of 1 quart of oil. In the test of the lubricating oil compositions of this invention, the 1-G test is run for 60 hours. At the end of this period, the engine is dismantled and rated for cleanliness. The ring lands are rated on a scale of 0 to 800, with 0 representing clean and 800 representing black deposits. The ring grooves are rated on a scale of 0 to 100% groove fill, with 0 representing clean. The underhead of the piston is rated on a scale of 0 to 10, with 0 representing dirty and 10 representing clean.

The base oil used in these tests is a Midcontinent base stock SAE 30 oil containing the noted millimols of calcium from the product being tested, as shown in Table I. The results of the testing of these lubricating oils are set forth in Table I.