GB2134538A

GB2134538A - Lubricating oils

Info

Publication number: GB2134538A
Application number: GB08400045A
Authority: GB
Inventors: Hiromichi Seiki
Original assignee: Idemitsu Kosan Co Ltd
Current assignee: Idemitsu Kosan Co Ltd
Priority date: 1983-01-20
Filing date: 1984-01-03
Publication date: 1984-08-15
Also published as: GB2134538B; DE3401149A1; JPS59133297A; DE3401149C2; GB8400045D0; FR2539755A1; FR2539755B1; JPH0153919B2

Abstract

Lubricating oils for use as engine oils comprise from 30 to 95% by weight of an ester of a hindered alcohol and an unsaturated fatty acid containing 18 carbon atoms, and from 70 to 5% by weight of a mineral oil and/or a synthetic oil.

Description

SPECIFICATION Lubricating oils The invention relatesto lubricating oils.

Various synthetic lubricating oils are known as lubricants for use at high temperature. Their upper temperature limits, however, are between 170 and 200 C. If they are used at temperatures above 200 C, various problems arise; for example, evaporation of the lubricating oil leading to loss of lubrication, orthe lubricating action ofthe lubricant is reduced or lost by theformation of sludge. Hence the conventional synthetic lubricating oils are not suitable for use at such high temperatures.

Lubricantsforusein an engine a superhigh temperature gas turbine bearing, turbocharged engines and so forth are required to withstand temperatures as high as 20000 or more, particularlytemperatures as high as 30000 or more.

Majorcharacteristics required for lubricants being used at such high temperatures are (1 ) the evaporation loss at high temperatures is small; (2) sludge is not formed at high temperatures; (3) stability against oxidation is good; and (4) load-carrying capacity is high.

The invention provides a lubricating oil comprising from 30 to 95% by weight of an esters a hindered alcoholandanunsaturatedfattyacidcontaining 18 carbon atoms and from 70 to 5% byweightofa mineral oil and/or a synthetic oil.

Various hindered alcohols can be used to form the ester, including those compounds represented by the general formula

wherein each of R1 to R4 independently represents a hydrogen atom, a hydroxy group, a hydroxyalkyl group or an alkyl group, provided that at least one of Ra to R4 represents a hydroxy group or a hydroxyalkyl group. The hydroxyalkyl and alkyl groups preferably contain from 1 to3carbon atoms. Preferred hindered alcohols are 2,2-di-(hydroxymethyl)-butanol, 2,2,di(hydroxymethyl)-propanol, pentaerythritol, 2methyl-2-hydroxymethylprnpanol and 2-methyl-2hydroxymethyl-pentanol. Alternatively, the hindered alcohol may be a compound such as dipen taerythritol.

Suitable unsaturated fatty acids include oleic acid, linoleic acid and linolenic acid. These acids may be used as their derivatives (e.g., acid halides).

Examples of suitable esters include 2,2-di(oleoyl oxymethyl)-butyl oleate, pentaeryth ritol tetraoleate, dipentaeryth ritol hexaoleate, 2-methyl-2-oleoyl-ox- ymethyl-propyl oleate, 2,2-di(li noleoyloxymethyl) butyl linoleate, pentaerythritoltetralinolate, dipen- taeryth ritol hexalinolate, 2-methyl-2-linoleoxymethyl-propyl oleate, 2,2-di(linolenoyloxymethyl) butyl linolenate, pentaerythritol tetralinolenate, dipentaerythritol hexalinolenate and 2-methyl-2linolenoyloxymethyl-propyl linolenate.

The mineral oil and the synthetic oil may be used singly or in combination with each other. Various types of mineral oils, such as naphthenic and paraffinic mineral oils, can be used. In general, those mineral oils which are known as lubricating base oils can be used. Also, various types of synthetic oils can be used. Examples of such synthetic oils include oeolefin polymers having a degree of polymerization of about from 20 to 200, such as ethylene homopolymers, propylene homopolymers, butene homopolymers and ethylene propylene copolymers; organic phosphates, such as alkyl phosphates and aryl phosphates; organic silicates, such as alkyl silicates and aryl silicates and carboxylates.These carboxylates include esters obtained by reacting dibasic acids such as adipic adic, azelaic acid and sebacic acid, or straight or branched chain saturated fatty acids containing from 5to 30 carbon atoms, with 2 ethylhexanol,s-butanol,3-methylbutanol or hindered alcohols.

The viscosity of the mineral oil or synthetic oil is not critical. In general, it is preferred to use a mineral oil or a synthetic oil having a kinematic viscosity at 10000 of at least 5 centistokes, especially from 10 to 50 centistokes.

The lubricating oil ofthe invention preferably contains from 50 to 90% by weight of the ester and from 50to 10% byweight ofthe mineral oil and/or syntheticoil. If the proportion of the ester is too small, the lubricating oil is notstable at high temperature, whereas if it is too large, the oxidation stability drops.

The lubricating oil according to the invention may, if necessary, further comprise various additives such as amine-, phenol-, and dithiophosphoric acid-type antioxidants,sulphonate-, phenete-, phosphonate-, and salicylate-type detergent dispersants, sulphur/ phosphorus-, and phosphate-type extreme pressure agents, and oiliness agents.

Even if the lubricating oil of the invention is used at temperatures as high as 20000 or more, particularly about 300, its evaporation loss is small and little sludge is formed. Furthermore the lubricating oil of the invention has a high oxidation stability and a high load-carrying capacity, Hence the lubricating oil ofthe invention is suitable forthe lubrication of machine elements subjected to high temperatures of 20000 or more, particularly in internal combustion engines; that is, is suitable for use as an engine oil.

The invention is illustrated bythefollowing Examples.

Examples 1 to 13 Lubricating oil compositions having the formulations described in the Table were prepared, and their physical properties were measured bythefollowing tests.

Thefollowing physical properties were tested.

TestofThermal Stability: A lubricating oil sample (30 grams) was placed in a beaker as specified in Figure 1 53 of JIS K2839 and maintained at320 Cfor3 hours.Attheend ofthe time, the evaporation loss and the formation of sludge were determined. Falex friction test of Load-Ca rrying Capacity: Indiana stirring oxidation test: 5 measured according to ASTM D3233.

measured according to JIS K2514. The results are shown in the Table.

TABLE EXAMPLE 1 2 3 4 5 6 7 8 9 Lubricating Oil Composition (parts by weight) Ester of 2,2-di (1)ydroxymethyl)-butanol and oleic acid 1 30 50 70 70 90 95 70 50 Ester of pentaerythritol and oleic acid; 50 Ester of pentaerythritol and linolir .cid'' Paraffinir mineral oil*@ 30 50 α;-olefin homopolymer*3 15 50 Saturated hindered ester 70 50 30 10 5 15 Phenotiazine 1 1 1 1 1 Dioctyldiphellyiamine a-Naphthylamine Calcium sulphonate (TPN 25) 5 5 5 5 5 5 Calcium phenate TBN 150) 5 5 5 5 5 5 Calcium salicylate (TICN- 170) 5 Tricresyl phosphate Physical Properties Test of Thermal Stability Evaporation loss ( by weught 25 21 19 20 17 15 20 28 27 Formation ol @hidge None None None None None None None None None Indiana stirring oxidation test Increase in viscosity (viscosity ratio! as determined at 40C 1.3 1.5 2.1 2.3 2.5 2.5 2.3 2.0 1.5 Total acid value 2.5 2.9 4.9 5.0 7.6 8.0 5.6 3.0 3.1 Falex friction test of load-carrying 1100 1100 1100 1100 1100 1100 1300 110 1000 Capacity (LBS) Table (Csmtimled) Example 10 11 12 13 Lubricating Oil Composition (parts by weight) Ester of 2.2-di(hydroxymethyl) -butanol and oleic acid*1 Ester of pentacrythritol is oleic acid*2 70 90 50 Ester of pentacrythritol nil linolic acid"3 30 Parafinic mineral ail*4 10 α-Olefin bumopolymer*5 30 Saturated hindered rater*6 50 70 Phonotiazius 1 1 Bioctyldiphenylamine 1 α;-Naphthylamina Calcium sulphorate (TBN-25) 5 5 Calcium phonata (TBN-150) 5 5 Calcium salicylate (TBN-170) 5 Tricresyl phosphate Physical Properties Test of Thermal Stability Evaporation loss (t b; weight) 22 16 29 21 Invention of sludge None None None None Indiana stirring oxidation test increase in viscosity (viscosity ratio) 2.4 2.5 1.9 1.7 as determined at ODC Total acid value 5.3 7.9 3.8 8.0 Falex friction test of Load-Carrying 1100 1200 1100 1100 Capacity (LBS) Note: : *1 Unister H-381 Fi, produced by Nippon Oils & Fats Co., Ltd.

*2 Unister H-481 R, produced by Nippon Oils & Fats Co., Ltd.

*3 Prepared by the esterification of pentaerythrito I and linolic acid.

*4 Viscosity at 100 C. 30 centistokes *5 Lucant HC, produced by Mitsui Petrochemical Co.

Ltd. (an ethylene-propylene copo lymer; viscosity (100 C):20 centistokes) *8 Composite ester of 2,2-di(hydroxymethyl)-buta nol, adipic acid, and stearic acid (Unister C-3373H, produced by Nippon Oils & Fats Co., Ltd.)

Claims

1. A lubricating oil comprising from 30to 95% by weight of an ester of a hindered alcohol and an unsaturatedfatty acid containing 18 carbon atoms and from 70 to 5% by weight of a mineral oil and/or a synthetic oil.

2. A lubricating oil according to claim 1 in which the hindered alcohol has the general formula

wherein each of R' to R4 independently represents a hydrogen atom, a hydroxy group, a hydroxyalkyl group or an alkyl group, provided that at least one of R1 to R4 represents a hydroxy group or a hydroxyalkyl group.

3. A lubricating oil according to claim 1 or claim 2 in which the hindered alcohol is 2,2-di(hydroxymethyl)-butanol, 2,2-di(hydroxymethyl)-propanol, pentaerythritol, 2 - methyl -2- hydroxymethyl propanol or 2 - methyl - 2 - hydroxymethyl - pentanol.

4. A lubricating oil according to any preceding claim in which the unsaturatedfatty acid is oleic acid, linoleicacid or linolenic acid.

5. A lubricating oil according to claim 1 or claim 2 in which the ester is 2,2 - di(oleoyloxy-methyl) - butyl oleate, pentaerythritol tetraloeate, dipentaerythritol hexaoleate, 2 - methyl - 2 - oleoyloxy - methyl - propyl oleate, 2,2-di(linoleoyloxymethyl)-butyl linoleate, pentaerythritol tetralinolate, dipentaerythritol hex alinolate, 2 - methyl -2- linoleoyloxymethyl - propyl oleate, 2,2- di(linolenoyl-oxymethyl)-butyl linolenate, pentaerythritoltetralinolenate, dipentaeryth ritol hexalinolenate or 2-methyl-2-linolenoyloxymethylpropyl linolenate trimethylolpropane trioleate, pentaeryth ritol tetraoleate, dipentaerythritol hexaloeate, neopentyl glycol dioleate, trimethyloilpropane trilinolate, pentaerythritoltetralinolate, dipentaerythritol hexalinolate, neopentyl glycol dilinolate, trimethylolpropanetrilimolenate, pentaeryth ritol tetralinolenate, dipentaerythritol hexalinolenate or neopentyl glycol dilinolenate.

6. A lubricating oil according to any preceding claim in,vghich the mineral oil is a naphthenic mineral oil or a paraffinic mineral oil.

7'. Alubricating oil according to any of claims 1 to 5i nwhichtiilisynthetic oil is an o:-olefin polymer having a degree of polymerization offrom 20 to 200, an organic phosphate, an organic silicate or a carboxylate.

81, Alubricating oil substantially as described herefnwith reference to any ofthe Examples.