GB1569439A - Synthetic lubricating oil - Google Patents

Description

(54) SYNTHETIC LUBRICATING OIL (71) We, TEXACO DEVELOPMENT CORPORATION, a Corporation organized and existing under the laws of the State of Delaware, United States of America, of 135 East 42nd Street, New York, New York 10017, United States of America, 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: This invention is concerned with synthetic lubricating oil compositions for bus or truck turbine engines.

Aliphatic esters formed by the reaction of pentaerythritol, a polypentaerythritol or trimethylolpropane and one or more organic acids having from 2 to 12 carbon atoms per molecule are inexpensive and would adequately provide lubrication to turbine engines except for their high pour points. However, their pour points canot be depressed if conventional depressants for mineral oils are used alone.

The prior art to which this invention relates includes inter alia U.S. Patents No: 2,796,402; 2,796,403; 2,796,404; 3,412,028; 3,476,685; 3,321,402; and 3,779,919. The last mentioned discloses the esters of this invention but in combination with the amine salts of a substituted rhodanine which imparts thereto corrosion-inhibiting and load carrying properties under high thermal and oxidative stress.

The present invention provides a synthetic lubricating oil composition which comprises (a) a major amount of an aliphatic ester base oil formed by the reaction of pentaerythritol, a polypentaerythritol or trimethylolpropane and one or more organic acids having from 2 to 12 carbon atoms, and (b) a pour point depressant amount of a mixture of a mineral oil having lubricating properties and a pour point from -40 F to + 35 0F, with a copolymer having a molecular weight from 5000 to 500,000, and derived from two or more esters of methacrylic acid having the formula

wherein R is an alkyl radical from butyl to stearyl. The compounded lubricating oils of this invention generally can be further improved by adding minor amounts of conventional corrosion inhibitors and other conventional property modifiers.

The base fluid of the lubricant of the invention is an ester-base fluid prepared from pentaerythritol, a polypentaerythritol, such as dipentaerythritol or tripentaerythritol, or trimethylolpropane and one or more organic acids.

The organic acids which are used to form the ester-base fluid include the straight-chain and branched-chain aliphatic acids, cycloaliphatic acids and aromatic acids as well as mixtures of these acids. The acids employed have from 2 to 12 carbon atoms per molecule. Examples of suitable specific acids are acetic, propionic, butyric, valeric, isovaleric, caproic, pelargonic, decanoic, cyclohexanoic, benzoic, phenylacetic, tertiarybutylacetic and 2-ethylhexanoic acids.

In general, the acids are reacted in proportions leading to a completely esterified pentaerythritol, polypentaerythritol or trimethylolpropane, with the preferred esters being the pentaerythritol esters.

The pour points of representative base oils are given below in Table I.

TABLE I POUR POINTS OF BASE OILS Pour Points ("F) Dipentaerythritol Ester of Nonanoic Acid +60 Pentaerythritol Ester of Nonanoic Acid +48 Pentaerythritol Ester of Octanoic Acid +20 Pentaerythritol Ester of Heptanoic Acid -25 Dipentaerythritol Ester of Hexanoic Acid +75 The mineral oil components of the compositions of the invention are lubricating oils having pour points ranging from -40 F to + 350F. The ranges of their other properties are: SpGr60/60"F 0.871-0.931 Gravity API 20.5 - 31.0 Flash COC F 250 minimum VIS SUS 100"F 80-400 VIS SUS 210 F 30-75 Suitable mineral oils give the following test results: A B C SpGr60/60 F 0.913-0.931 0.871-0.887 0.871-0.892 Gravity API 20.5 - 23.5 28.0 - 31.0 27.0 - 31.0 Flash COC F 355 minimum 425 minimum 350 minimum VIS SUS 100"F 300 - 324 325 - 350 97 - 105 VIS SUS 210 F 46.0 - 49.0 53.0 - 55.0 36.0 - 39.0 Pour "F -20 maximum 10 maximum 25 maximum Ash % 0.003 maximum 0.003 maximum 0.003 maximum Neut. No. 0.10 maximum 0.10 maximum 0.10 maximum The mineral oil component is preferably used in amounts ranging from 2 to 35 weight percent of the lubricant composition.

The polymeric pour point depressants used in the present invention are methacrylate polymers used with or without a mineral oil diluent.

Methacrylate polymers are well known V.I. improvers and pour point depressants. These methacrylate polymers are copolymers of two or more esters of methacrylic acid and have a molecular weight between 5000 and 500,000. The polymethacrylate esters are copolymers of two or more methacrylic acid esters of the following general formula:

wherein R is an aliphatic radical preferably ranging from butyl to stearyl.

Copolymers which find particular use as V.I. improvers and pour point depressants are the following: a copolymer wherein R in the above formula comprises 20%lauryl, octyl and 40% cetyl; a copolymer wherein R in the above formula is 50% stearyl and 50% lauryl; a copolymer wherein R in the above formula comprises 50% lauryl and 50% octyl.

Methacrylate polymers used as pour depressants are usually sold as concentrates comprising approximately 20 to 50% polymer in a carrier oil. The carrier oil can be either a mineral oil or an ester type oil. Typical ester-type oils are dioctyl sebacate, trimethylolpropane tripelargonate or C2 to C12 acid-derived mixed esters of pentaerythritol. An example of the last-named material is MW 14918 manufactured by Drew Chemical Corp., New York, N.Y.

Dispersant-type methacrylate copolymers, for examples Acryloid HF-866 manufactured by Rohm and Haas, incorporating, in addition to alkyl methacrylate esters, nitrogen containing monomers such as vinylpyrrolidone or dimethylaminoethylmethacrylate, are particularly effective, they are described in U.S. Patents No. 3,142,664, 3,147,222 and 3,153,640. The methacrylate polymers can constitute between 0.005 to 5.00%of the composition of the final blend.

Typical pour depressants are described in Table II below: TABLE H INDENTIFICATION OF POUR DEPRESSANTS "D" 33 wt. % of a polymer of average molecular weight 180,000 + 10%, prepared from 75% Neodol 25 L synthetic lauryl methacrylate and 25%Alfol 1620 stearylmethacrylate ("Alfol" is a Registered Trade Mark) and 67 wt. % mineral oil diluent.

"E" 25 wt. % of Acryloid HF-866 polymer (average molecular weight 180,000 + 10%) and 75 wt. % of Drew Corporation 14918 synthetic ester base stock.

The invention is further illustrated but not limited by the Examples which follow.

In carrying out the procedure of the examples blends having the indicated compositions were prepared by blending samples having a total weight of 50 gm. with thorough mixing.

Then pour points were determined using ASTM Test D-97, "Pour Point of Petroleum Oils." EXAMPLE I ( F) Pour 100% Dipentaerythritol Ester of Nonanoic Acid +60 80% C9-DiPE ester/20% "B" +50 79.0% C9-Di PE ester/20% "B8/1%"B +15 EXAMPLE II 100% Pentaerythritol Ester of Nonanoic Acid +48 79.5% Cg PE ester/0.5% "D"/20% "B" +20 99.5% Cg PE ester/0.5% "D" +48 EXAMPLE HI 100% Pentaerythritol Ester of Octanoic Acid +20 99.5% C8 PE ester/0.5% "D" +20 80.0% C8 PE ester/20.0% "B" 0 79.9% C8 PE ester/20% "B"/0.1% "EE -5 79.9% C8 PE ester/20% "B"/0.1% "D" -5 79.5% C8 PE ester/20% "B"/0.5% per. -15 EXAMPLE IV 100% Pentaerythritol Ester of Octanoic Acid +20 89.5% C8 PE ester/10% "B"/0.5% "E" 0 79.5% C8 PE ester/20% "B"/0.5% "E" -15 69.5% C8 PE ester/30% "B"/0.5% "E" -12 EXAMPLE V 100% Pentaerythritol Ester of Heptanoic Acid -25 80% C7 PE ester/20% "B" 0 75.8% C7 PE ester/20% "B"/0.2% DE" -65 EXAMPLE VI 100% Dipentaerythritol Ester of Hexanoic Acid +75 79.5% C6 Di PE ester/20% "B"/0.5% "E" +40 EXAMPLE VII 100% Pentaerythritol Ester of Octanoic Acid +20 80% C8 PE ester/20% "C" +10 79.5% C8 PE ester/20% "C"/0.5% "D" + 5 EXAMPLE VHI 100% Pentaerythritol Ester of Octanoic Acid +20 79.5% C8 PE ester/20% "A"/0.5% "D" 0 The foregoing Examples I, II, III, V demonstrate that a combination of mineral oil and pour depressant is more effective in depressing the pour point than either a mineral oil or pour depressant alone.

Example IV shows that the invention is operable at varied concentrations of mineral oil (10-30% "B").

Example VI gives further confirmation of the data presented in Examples I-V.

Examples VII and VIII show that the invention is operable with more than one mineral oil.

While the proportions of constituents given in the foregoing description give outstanding pour point depression with the given base oils, it will be appreciated that by following the teaching of the invention those skilled in the art will be able without undue experimentation to determine optimum composition ranges for other oils.

It is to be understood that the foregoing specific examples are presented by way of illustration and explanation and that the invention is not limited by the details of such examples.

WHAT WE CLAIM IS: 1. A synthetic lubricating oil composition which comprises (a) a major amount of an aliphatic ester base oil formed by the reaction of pentaerythritol, a polypentaerythritol or trimethylolpropane and one or more organic acids having from 2 to 12 carbon atoms, and (b) a pour point depressant amount of a mixture of a mineral oil having lubricating properties and a pour point from - 40 F to + 350F, with a copolymer having a molecular weight from 5000 to 500,000, and derived from two or more esters of methacrylic acid having the formula

wherein R is an alkyl radical from butyl to stearyl.

2. A composition as claimed in Claim 1 which contains from 2 to 35%by weight of the mineral oil.

3. A composition as claimed in Claim 1 or 2 which contains from 0.01 to 5.0% by weight of the polymer.

4. A composition as claimed in any of Claims 1 to 3 wherein the ester is the dipentaerythritol ester of nonanoic acid. the pentaerythritol ester of nonanoic acid, the pentaerythritol ester of octanoic acid, the pentaerythritol ester of heptanoic acid, or the dipentaerythritol ester of heptanoic acid, or the dipentaerythritol ester of hexanoic acid.

5. A composition as claimed in Claim 1 and substantially as hereinbefore described with reference to any of Examples I to VIII.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. EXAMPLE VHI 100% Pentaerythritol Ester of Octanoic Acid +20 79.5% C8 PE ester/20% "A"/0.5% "D" 0 The foregoing Examples I, II, III, V demonstrate that a combination of mineral oil and pour depressant is more effective in depressing the pour point than either a mineral oil or pour depressant alone. Example IV shows that the invention is operable at varied concentrations of mineral oil (10-30% "B"). Example VI gives further confirmation of the data presented in Examples I-V. Examples VII and VIII show that the invention is operable with more than one mineral oil. While the proportions of constituents given in the foregoing description give outstanding pour point depression with the given base oils, it will be appreciated that by following the teaching of the invention those skilled in the art will be able without undue experimentation to determine optimum composition ranges for other oils. It is to be understood that the foregoing specific examples are presented by way of illustration and explanation and that the invention is not limited by the details of such examples. WHAT WE CLAIM IS:

1. A synthetic lubricating oil composition which comprises (a) a major amount of an aliphatic ester base oil formed by the reaction of pentaerythritol, a polypentaerythritol or trimethylolpropane and one or more organic acids having from 2 to 12 carbon atoms, and (b) a pour point depressant amount of a mixture of a mineral oil having lubricating properties and a pour point from - 40 F to + 350F, with a copolymer having a molecular weight from 5000 to 500,000, and derived from two or more esters of methacrylic acid having the formula

wherein R is an alkyl radical from butyl to stearyl.

2. A composition as claimed in Claim 1 which contains from 2 to 35%by weight of the mineral oil.

3. A composition as claimed in Claim 1 or 2 which contains from 0.01 to 5.0% by weight of the polymer.

4. A composition as claimed in any of Claims 1 to 3 wherein the ester is the dipentaerythritol ester of nonanoic acid. the pentaerythritol ester of nonanoic acid, the pentaerythritol ester of octanoic acid, the pentaerythritol ester of heptanoic acid, or the dipentaerythritol ester of heptanoic acid, or the dipentaerythritol ester of hexanoic acid.

5. A composition as claimed in Claim 1 and substantially as hereinbefore described with reference to any of Examples I to VIII.