A LUBRICANT COMPRISING AN ALKYL-SUBSTITUTED NAPHTHALINE AND AN ESTER

Abstract: A lubricant comprising alkyl-substitued naphthalene and an ester.

Description: A LUBRICANT COMPRISING AN ALKYL-SUBSTTTUTED NAPHTHALINE AND AN ESTER The present invention relates to lubricant comprising an ester. More particularly, the invention relates to high temperature chain oils having improved volatility and functional life. Lubricant compositions for use on drive chains, particle board presses, tenter frames and stenter frames require viscosity stability. Prior lubricant compositions, which have included esters, have not been satisfactory for use with drive chains at high temperatures due to the viscosity change experienced by esters at high temperatures. Although compositions employing polyalphaolefins do not exhibit the same viscosity change experienced by esters, oils having polyalphaolefins also have not proven satisfactory due to the tendency to form varnish under thin film conditions. Other deficiencies of prior lubricant compositions include unacceptable volatility and inadequate functional lifetime. The present invention overcomes these and other disadvantages by including an alkyl-substituted naphthalene in a lubricant composition having an ester. One object of the present invention is the provision of a lubricant for use with drive chains and other chain mechanisms operating in high temperature environments having improved viscosity characteristics. Another object of the invention is to provide a high temperature chain oil having improved volatility characteristics and an increased functional life. The lubricant composition of the present invention comprises an alkyl-substituted naphthalene and an ester. In referring to an alkyl-substituted naphthalene, it is contemplated that reference is made to naphthalene substituted with one or more straight or branched alkyl groups of varying lengths. The inclusion of one or more alkyl-substituted naphthalene compounds in a lubricant composition having an ester results in unexpected improvements, such as an increase in the functional life of the oil, as well as a decrease in the overall volatility of the oil. The present invention comprises an amount of alkyl-substituted naphthalene sufficient to improve the volatility of the lubricant composition. Alternatively, the invention comprises an amount sufficient to increase the functional life of the lubricant. Generally the alkyl-substituted naphthalene comprises from about 10 percent to about 50 percent by weight of the lubricant composition, alternatively from about 12 percent to about 30 percent. Unless otherwise indicated, throughout this specification, the amounts of the components are listed in percentages by weight of the total composition. Esters which may be used in the present invention are disclosed in Kirk-Othmer Encyclopaedia of Chemical Technology, (4th ed. 1994), vol. 9, pp. 781-812, which is incorporated by reference herein. More particularly, the present invention may comprise diesters, phthalates, trimellitates, pyromellitates, dimer acid ester, polyols and polyoleates. It is contemplated that trimellitic esters and polyols are particularly suitable. In certain embodiments, an ester comprises from about 40 percent to about 90 percent by weight of the lubricant composition, alternatively from about 50 percent to about 80 percent. EXAMPLES The following examples provide a basis for understanding the nature of the invention and are not limitations upon the scope of the invention. The examples below represent different embodiments of the invention having different viscosity grades. Example I Example II Emkarate 9130 70% 63.4% Mobil MCP 968 15% 18% Indopol H-1900 — 16% Parapol 1300 13% ~ Irgalube 349 0.6% 0.6% Irganox L06 0.6% 1% Vanlube SS 0.4% 0.6% Nasul 707 0.4% 0.4% Emkarate 9130 is a trimeilitic acid ester, available from ICI Chemical Polymers. Mobil MCP 968 is a mixture of dialkyl- and trialkylnaphthalenes, available from Mobil Chemical Co. Parapol 1300 and Indopol H-1900 are polybutene polymers. Irgalube 349 is an antiwear additive available from Ciba-Geigy PLC. Irganox L06 is an antioxidant, also available from Ciba-Geigy PLC. Vanlube SS is an antioxidant available from RT Vanderbilt Chemical Corp. Finally, Nasul 707 is an anti-corrosive agent available from King Industries. I is contemplated that in a commercial preparation of the embodiment disclosed as Example I, the specified amounts of Emkarate 9130 and Mobil MCP 968 are combined and heated to a temperature of from about 70°C to about 85°C. Subsequently, Parapol 1300 (or Indopol H-1900), Irganox L06 and Vanlube SS are blended into the mixture. Irganox L06 and Vanlube SS are powders which must be melted into the mixture, and the mixture must be blended until the Irganox L06 and Valube SS are thoroughly dispersed in the mixture. The temperature of the composition is then lowered to about 60°C and Irgalube 349 and Nasul 707 are blended into the composition. Samples of the lubricant compositions of the preceding Examples were prepared in accordance with the steps outlined in the preceding paragraph. To assess the volatility of the composition, the isothermal evaporation of several samples was measured by subjecting a sample to the constant temperature in an instrument specifically designed for thermo-gravimetric analysis by TA Instruments. In the results below, "t90" represents the time at which 10 percent by weight of the original sample had volatized (i.e., 90 percent by weight of the sample remained), and "T50" indicates the time at which 50 percent by weight of the original sample had volatized (i.e., 50 percent by weight of the sample remained). Example I Example II 200°C t90 > 10 hours > 10 hours t50 > 10 hours > 10 hours 225°C t90 2.2 hours 3.5 hours t50 > 10 hours > 10 hours 250°C t90 0.60 hours 1.3 hours t50 3.3 hours 5.5 hours 275°C t90 0.31 hours 0.35 hours t50 1.3 hours 1.3 hours These test results show the beneficial and improved volatility characteristics of the present invention. The superiority of the present invention can be seen by comparing the volatility characteristic of Example I with the volatility characteristics of a sample (Formula B) which does not include an alkyl naphthalene compound. Formula B is comprised of: Emkarate 9130 85% Mobil MCP 968 ~ Parapol 1300 13% Irgalube 349 0.6% Irganox L06 0.6% Vanlube SS 0.4% Nasul 707 0.4% Formula B has the same ingredients in the same amounts as Example I except that in place of Mobil MCP 968 (a mixture of dialkyl- and trialkyl-naphthalenes), Formula B has additional Emkarate 9130 (a trimeilitic acid ester). Isothermal scans on 10 to 12 mg samples of Example I and Formula B were run at four different temperatures. The following results indicate the time at which 50 percent by weight of the original sample had volatized at each of the four temperatures (i.e. 50 percent by weight of the sample remained). Example I Formula B 225°C t50 > 10 hours 7 hours 250°C t50 3.3 hours 2.4 hours 275°C t50 1.4 hours 0.6 hours 300°C t50 0.25 hour 0.20 hour At each of the tested temperatures, the lubricant of Example I took longer to volatilize to the extent where fifty percent of the lubricant was no longer present. These results demonstrate that the invention's improvement of volatility can be observed over a wide temperature range. The lubricant composition of the present invention is notable for its ability to meet the demands of use of high temperature drive chain applications. However, the present invention is also suitable for use in other applications, such as gears and air compressors, as well as for any lubricant application where low volatility and increased functional life are desirable. The above specification, examples and data provide a basis for understanding and using the disclosed invention. However, any embodiment of the invention within the scope of the disclosure is within the spirit and scope of the invention.

Claims: Claims 1. A lubricant comprising an alkyl-substituted naphthalene and an ester. 2. The lubricant claimed in claim 1 , wherein the lubricant comprises from about 10 to about 50 percent, preferably from about 12 to about 30 percent, by weight of alkyl-substituted naphthalene 3. The lubricant claimed in claims 1 or 2, wherein the lubricant comprises at least one ester selected from: diesters, phthalates, trimellitates, pyromellitates, dimer acid esters, polyols and polyoleates 4. The lubricant claimed in any one of the preceding claims, wherein the lubricant comprises from about 40 to about 90 percent, preferably from about 50 to about 80 percent, by weight of the ester. 5. Use of the lubricant claimed in any one of the preceding claims as a lubricant for drive chains, particle board presses, tenter frames and stenter frames. 6. Use of alky-substituted naphthalene in a lubricant comprising an ester to reduce the volatility of the lubricant at increased temperatures.

Inventors: KRINKER RANDALL, KRINKER, RANDALL
Applicants: CASTROL LTD, KRINKER RANDALL, CASTROL LIMITED, KRINKER, RANDALL
Application year: 1997
Main classification: C10M169
IPC codes: C10M105, C10M111, C10M127, C10M129, C10M169, C10N30, C10N40