SE185309C1 - - Google Patents

Description

Inventors: VA Moffatt and RE Hutton Prtoritet requested from October 9, 1959 and September 13, 1960 (United Kingdom). The present invention relates to a synthetic lubricant, which is characterized in that it contains an ester of an aliphatic dicarboxylic acid and a matt, aliphatic, monohydric alcohol. , with a backbone of at least 5 carbon atoms, two alkyl or cycloalkyl groups on the beta carbon atom and at least one alkyl or cycloalkyl group on the gamma carbon atom and optionally one or more auxiliaries.

The dicarboxylic acid component of the esters may contain 4-22 and preferably 6-12 carbon atoms. Among dicarboxylic acids, those in which the carboxylic acid groups are in the alpha-omega formulations and which are straight-chain and matt are particularly preferred. The dicarboxylic acids may contain heteroatoms other than those present in the carbonic acid groups, for example oxygen, and examples of such acids are polyoxyalkylene dicarboxylic acids having 2-10 oxyalkylene groups. The dicarboxylic acids may optionally contain short alkyl substituents in the chain, for example methyl, ethyl and isopropyl substituents. East among the aliphatic dicarboxylic acids, however, are the straight-chain manacle aliphatic dicarboxylic acids, for example malonic acid, succinic acid and glutaric acid, and especially those acids which contain 4-8 carbon atoms in the chain, such as adipine, suberine, azelaine, pimelino and sebacine.

The esters of the invention may be prepared by a method comprising esterification in the presence of an esterification catalyst of a dicarboxylic acid and a saturated aliphatic monohydric alcohol having a backbone of at least 5 carbon atoms, 2 alkyl or cycloalkyl groups on the beta carbon atom and at least 1 alkyl or cycloalkyl group on gamma -atoms. The alcohol suitably contains 8-30, preferably 8-14 carbon atoms, while the (cyclo) alkyl groups contain 1-6, preferably 1-3 carbon atoms. Mixed asymmetric esters can be prepared by esterifying one or more dicarboxylic acids with a mixture of two or more of said monohydric alcohols. Elated esters can also be prepared by esterifying one or more dicarboxylic acids with a mixture of one or more of the said monohydric alcohols and one or more other monohydric alcohols.

The esterification procedure is preferably carried out at elevated temperature, whereby reaction temperatures in the range of 80-2 ° C can be used. Suitable catalysts are sulfuric acid and arylsulfonic acids, such as p-toluenesulfonic acid and sulfosalicylic acid. Preferably, in the forming process, a water-removing substance, such as benzene, toluene or xylene, is used to continuously remove the water poured during the reaction by azeotropic distillation. Alternatively, an inert gas may be passed through the reaction mixture to remove the water formed. After the final reaction, the reaction mixture can be washed with dilute alkali solution to remove the catalyst and any free carboxylic acids present. If necessary, the ester can then be heated under reduced pressure to remove any free alcohol present. The ester can also be treated with an absorbent soil as final treatment, if necessary.

Examples of the new esters according to the invention, which are particularly suitable as ester lubricants, are hi. a. di (2,2,3-trimethylpentyl) sebacate, di (2,2,3-trimethylpentyl) azelate, dimethyl-3-ethylhexyl) adipate, di (2,2-dimethyl-3-ethylpentyl) sebacate, di (2,2,3-trimethylpentyl) suberate, (2,2,3-trimethylpentyl) - (2,2,3-trimethylhexyl) sebacate, di (2,2-diethyl-3-isopropylpentybazelate, triethylpentyl) pimelate, ( 2,2,3-trimethylpentyl) (2,2,3-trimethylhexyl) adipate, di (2-cyclopentyl-2,3-dimethylpentyl) sebacate, (2-cyclopentyl-2,3-diethylhexyl) (2,2 , 3-trimethylpentype suberate, (2,2,3-trimethylpentyl) (2,2,4-trimethylpentyl) sebacate; (2,2,3-trimethylpentyl) (2,2,3,3-tetramethylpentyl) sebacate, (2, 2,3-trimethylpentyl) (2,2-dimethylpentyl) seb acate 2 - As already mentioned, the esters according to the invention constitute valuable synthetic lubricants. Lubricating oils consisting of synthetic esters are of particular value for use in aircraft and gas turbines, in that they have special properties which are not found in conventional lubricating oils, so they must have a very high viscosity index in order to give adequate lubrication with a wide temperature range. They must show great resistance to oxidation and heating, so they retain their good properties during long-term use at high temperatures. They must have a low pour point, so that they can function at low temperatures, high ignition temperature avoids fire risk at high operating temperatures and finally low volatility to avoid lubricant losses by evaporation. Structural isomers to the intended esters are known, for example the dicarboxylic acid ester of 2,2,4-trialkylols, 3,5,5-trialkylols, 2,3,3-trialkylols and 3,3,5-trialkylols, but surprisingly the esters of the invention have been found to be these Una. esters Overall, especially with regard to viscosity. SO e.g. aro the viscosities at 38 C resp. 99 ° C of di (2,2,3-trimethylpentyl) sebacate and di (2,2,4-trimethylpentyl) sebacate as follows: Viscosity at 38 ° C99 ° C di (2,2,3-trimethylpentyl) sebacate 23.7 cs4,89 cs di (2,2,4-trimethylpentyl) - sebacate 14,96 cs3,82 es The viscosity at 38 ° C of the 2,2,3-ester is thus almost 1.6 times as large a sum of 2,2 , 4-ester.

Furthermore, the thermal stability of dicarboxylic acid esters of 2,2,3-trialkylols is more rigid than that of dicarboxylic acid esters of alcohols in general, for example the esters of 3,3,5-trimethylhexyl alcohol: Increase in acid number of di (2,2,3-trimethylpentyl) sebacate 0, 9 di (3,5,5-trimethylhexyl) sebacate 13.6 The thermal stability test is carried out by heating the ester for 24 hours at a temperature of 280 ° C in a nitrogen atmosphere and feeding the acid number before and after the test.

Although the synthetic esters of the invention according to the invention are generally superior to the known isomeric synthetic ester lubricants, they nevertheless require certain uses and additives, such as viscosity index improving medallions, thickeners, antioxidants, antihypertensives and antifoulants.

Highly suitable additives acting as thickeners increase the viscosity of the synthetic lubricating oils of the invention at elevated temperatures. Polymers of esters of acrylic acid or a 2-alkyl acrylic acid. The most suitable polymers have a relative molecular weight between 100 and 180 centistokes, but polymers with a relative molecular weight as high as 400 centistokes are of varcleful nature. By the term "relative molecular weight" is meant the centistoke viscosity at 38 ° C of a 30% solution of the polymer in toluene. . Typical esters whose polymers can be used in this way are the methyl, ethyl, n-propyl, isopropyl, isobutyl, lauryl, phenyl or benzyl esters of acrylic, methacrylic, 2-ethylacrylic and 2-propylacrylic acid. Typical suitable and commercially available polymers Oro methyl acrylate and methyl methacrylate polymers with a relative molecular weight of 160 centistokes. The polymers may be composed of homopolymers of a single ester or may be copolymers of a mixture of such esters, and the term "polymer" shall therefore be used in this table. The polymers can be incorporated into the synthetic lubricating oils of the invention in an amount of 2-30% by weight of the total weight of the liquid esters and polymers. In general Concerns 5-15% by weight the most appropriate prop ortion Mom named area.

Polymers of acrylic acid esters and methacrylic acid esters which are suitable for use in the synthetic lubricating oils according to the invention can be obtained in the form of commercial products. They are on the market as concentrated dispersions in a solvent, and these concentrated dispersions can be used as such.

Some of the commercially available polymers which are suitable for use in the synthetic lubricating oils of the invention are not stable to cutting, and if such polymers are used, it is advisable to subject them to a splicing action, for example by passing them through an injection nozzle. they are incorporated with lubricating oils.

Another class of thickeners is given by the synthetic lubricating oils of the invention, the optional complex esters which are prepared by the esterification of a polyalkylene glycol, a matt dicarboxylic acid and an alkanol. A particularly suitable additive of this type is prepared by esterifying 1 mole of a polyalkylene glycol, 2 moles of a matte dicarboxylic acid and 2 moles of a matte branched chain alkanol. The most suitable ester is that obtained by the esterification of 1 mole of tetraethylene glycol, 2 moles of sebacic acid and 2 moles of a trimethylhexanol.

A further class of thickeners are polymers prepared by polymerizing C6-C olefins or mixtures thereof in the presence of a Ziegler catalyst consisting of components A and B, wherein A Or is a simulation of a Group 4a, 5a, 6a metal. 7a or 8 of the Periodic Table and B consists of an element or a compound of (a) a Group 1 metal or alloy thereof or (b) an organometallic compound or a hydride of a Group 1, 2 or 3 metal, tents or lead, the ratio between A. and B being 1: 1 or Or starre, as described more closely in patent no. (p. ans. no. 1252/60).

Another class of thickeners which may be used are the polyoxyalkylene glycols and their mono- and diesters of the general formula: 1: 11-0 (11.0). R 2 where R 1 and R 2 each represent a hydrogen atom, a non -aromatic hydrocarbon radical or an acyl group, R, represents an alkylene radical and 11 is an integer. These polyoxyalkylene compounds are described in more detail in British Patent 786,950.

Suitable lacquers against the substances for addition to the synthetic lubricating oils according to the invention are the salts of aromatic carboxylic acids or phenols and a metal from the Group II of the Periodic Table, which salts are soluble in the synthetic lubricating oil. These salts increase the oxidation and heat stability of the synthetic lubricating oils at high operating temperatures and prevent paint formation in the bearings. Of Group II metals, zinc and potassium are bases for the purposes of the invention, but beryllium, magnesium, strontium, cadmium, barium or mercury salts may be used. The aromatic carboxylic acid or phenol selected should have sufficient oleophilic properties to ensure that the metal salt used is soluble in the liquid ester mixture. Preferably, these salts are used in such amounts that there is a metal content in the finished lubricating oil between 0.01 and 1.0% by weight. Normal or basic salts or mixtures of normal and basic salts can be used. Suitable aromatic acids for use in the form of salts with metals of group II in the lubricating oils according to the invention. and octyl 1-4-hydroxybenzoic acids. The salts of the alkylated hydroxybenzoic acids are particularly valuable and can be used in admixture with each other. Thus, salts of mixtures of alkylated hydroxybenzoic acids obtained by reacting salicylic acids or 4-hydroxybenzoic acid with a mixture of alkenes, such as a mixture obtained by cracking paraffin wax, or with a mixture of alcohols in the presence of a suitable condensing agent of Friedel-Craft can be used. -type. On similar salt you can use salts of a mixed. ring obtained by alkylating a phenol with such a mixture of alkenes or alcohols and converting the alkylphenols formed to Kolbe-Schmidt salicylic acids.

Particularly effective metal salts of this type for use in the lubricating oils of the invention are the zinc salts of alkylated salicylic acids containing 12-20 carbon atoms in the alkyl group. A particularly active compound is the zinc salt of a mixture of alkylsalicylic acids prepared by alkylating phenol with a mixture of alkenes containing 14-18 carbon atoms in the molecule and converting the resulting alkylphenols to the corresponding salicylic acids according to Kolbe-Schinidt's method.

Suitable phenols for use in the lubricating oils of the invention in the form of salts with Group II metals are phenol itself, naphthols, cresols and higher alkylated phenols, such as amyl, octyl, nonyl, decyl, tetradecyl, pentadekyl and octadecyl phenols. Salts of mixtures of alkylphenols, for example those obtained by general alkylation of a phenol with mixtures of alkenes, can be used and preferred because of their lower melting points compared to the pure alkylphenols. Mixtures of alkenes derived from paraffin wax by cracking or from higher fatty alcohols by dewatering are valuable and readily available starting materials for the preparation of such phenolic mixtures. In addition, a mixture of alkylphenols prepared by alkylation of phenol or a cresol or 1 or 2-naphthol with a mixture of alkenes containing 8 to 18 carbon atoms in the molecule and obtained can be used in the above procedure. More than one alkyl or alkenyl group may be present in the phenol, as is the case with compounds prepared by partial trialkylation of phenols with alkenes, alkyl halides, alcohols or ethers, or with compounds prepared by monoalkylation of, for example, a cresol, a xylenol, carvacrol or cardanol. Other nucleus substituents may be present, provided that they do not unduly reduce the oil solubility of the phenol. Thus, halogen, alkoxy, alkyl mercapto and alkylamino groups may be present in the phenol.

Among the salts of phenols with metals of Group II Concerns that have been harlet Iran condensation products of certain hydrocarbon-substituted phenols are particularly effective. More specifically, these condensation products are those prepared from a carbonate-substituted phenol containing at least 4 carbon atoms in the substituent and capable of reacting with formaldehyde or acetaldehyde or a polymer thereof, such as paraformaldehyde. These condensation products can be converted into salts by reaction with basic compounds of Group II metals or the salts can be prepared directly by carrying out the condensation reaction in the presence of a basic compound of a Group II metal, preferably in the presence of an inert diluent.

A particularly suitable salt for use in the lubricating oils of the invention may be prepared as follows (parts indicated by weight): 60 parts of para-tert-octylphenol are stirred in 260 parts of a solvent refined mineral lubricating oil containing 1 part of water, and 9.7 parts of potassium hydride and 10.1 parts of paraformaldehyde are added. The mixture is heated to 8 ° C, the temperature is then raised to 95 ° C for a period of 30 minutes and Mlles at 95 ° C for a further 1 hour, whereupon it is filtered hot to obtain a concentrate having a calcium content of 1.2%.

The incorporation of polymers of esters of acrylic acid or a 2-alkyl acrylic acid or a 2-alkyl acrylic acid with a salt of an aromatic carboxylic acid or of a phenol with a metal of Group II of the Periodic Table in liquid esters of dicarboxylic acids is preferred for British patent 703 445.

Since very high load bearing capacity is required, a high pressure agent can be added to the synthetic lubricating oils of the invention. A suitable type of high pressure lubricant for the lubricating oils are trialkyl, triaryl or trialkaryl phosphates, such as trioctyl or tricresyl phosphate. High pressure agents of the haloalkylphosphonate type, such as monobutylvatetrichloromethylphosphonate and its aminal ester, as well as its salt with di (2-ethylhexyl) amine are also suitable.

Antioxidants, especially of the phenolic or amine type, can be added to the lubricating oils according to the invention. Preferably, such antioxidants are not volatile at the highest temperature which occurs during the use of the lubricating oil. Alkylated phenols and diphenols, phenyl-1-naphthylamine, diphenylamine and phenothiazine and their alkyl and halogen substitution products are suitable antioxidants. Organoselenium compounds, such as dilauryl selenide, can also be used.

The invention is claimed but should not be construed as limited by the following examples, in which parts and percentages are by weight respectively. weight percent.

Example 1.

A mixture of 196 parts of crotyl alcohol, 293.5 parts of isobutyraldehyde, 450 parts of tetralin and 0.6 parts of p-toluenesulfonic acid was introduced into a vessel equipped with a thermometer and a packed column with a Dean & Stark trap. The mixture was heated at reflux for 26 hours, during which time 54.1 parts of water were collected in Man. After cooling, the column was replaced with a fractionation column equipped with a variable reflux passage and the reaction mixture was fractionated. The fraction boiling in the range of 149-154 ° C was collected and found to be 2,2,3-trimethyl-4-pentene. Example 2. 217 parts of 2,2,3-trimethyl-4-pentenal, 180 parts of methanol and parts Raney nickel was introduced into a reaction vessel and hydrogenated at 125 ° C and 125 atm. print. The end of the reaction was indicated by the cessation of water uptake. The catalyst was removed by filtration and the filtrate was distilled, yielding 199.5 parts of 2,2,3-trimethylpentanol (89% yield) boiling at 72-74 ° C / 16 mm Hg and having a refractive index of 1.4398.

Example 3. 101.1 parts of sebacic acid, 135.5 parts of 2,2,3-trimethylpentanol, 90 parts of benzene and 0.5 parts of concentrated sulfuric acid were heated by refluxing in a vessel equipped with a water-cooled Dean & Stark pass and mechanical stirrer. Heating was continued until no additional water accompanied the benzene.

The crude reaction product was washed 4 times with 100 parts of water, the acid number was determined and 1.2 parts of potassium hydroxide in 45 parts of methanol were added with stirring. The oil was then washed 4 times with 200 parts of water and azeotroped, the benzene was removed by distillation and the product was finally evaporated at 220 ° C and 0.7 mm Hg. The yield of di (2,2,3-trimethylpentyl) sebacate was 82.3%, ng = 1.4553.

Viscosity at 99 ° C 4.89 cs Viscosity at 38 ° C 23.7 cs Viscosity at —40 ° C 93cs KV I 1 Pour point below —75 ° C Example 4.

The previous example was repeated using a mixture of equimolar parts 2,2-dimethylpentanol and 2,2,3-trimethylpentanol instead of the 2,2,3-trimethylpentanol of Example 3 and using sodium bisulfate (1% by weight stripped of sebacic acid) as catalyst: The product consisted of a co-ester with the following data: Viscosity at 99 ° C 4.03 cs Viscosity at 38 ° C 17.7 es Viscosity at -40 ° C 4850 es KVI 149 Pour point below —75 ° C

Claims (12)

Patent claim: Synthetic lubricant, characterized in that it contains an ester of an aliphatic dicarboxylic acid and a saturated, aliphatic, monohydric alcohol having a basic chain of at least 5 carbon atoms, two alkyl or cycloalkyl groups on. the beta carbon atom and at least one alkyl or cycloalkyl group on the gamma carbon atom and optionally one or more helical substances. 2. Lubricant according to claim 1, characterized in that the dicarboxylic acid contains 422, preferably 6-12 carbon atoms. Lubricant according to claim 1 or 2, characterized in that the dicarboxylic acid removes the carboxyl groups in all the α-omega compositions. Lubricant according to any one of claims 1-3, characterized in that the dicarboxylic acid is straight-chain and matt. 5. Lubricants according to any one of claims 1-4, characterized in that the alcohol contains 8-30, preferably 8-14 carbon atoms. 6. A lubricant according to any one of claims 1-5, characterized in that the (cyclo) alkyl groups in the alcohol contain 1-6, preferably 1-3 carbon atoms. A lubricant according to any one of claims 1-6, which may be claimed (Wray, that the ester is di (2,2,3-trimethylpentyl) sebacate. Lubricant according to any one of claims 1-7, characterized in that a polymer of an ester of acrylic acid or a 2-alkyl acrylic acid, preferably in an amount of between 2 and 30% by weight, based on the total weight of the ester and the polymer, is present. A lubricant according to any one of claims 1 to 7, characterized in that a complex ester obtained by esterification of a polyalkylene glycol, a matt dicarboxylic acid and an alkanol is present. Lubricant according to any one of claims 1-7, characterized in that a polyoxyalkylene glycol or a mono- or dieter or ester (bray of the general formula R 1 -O (R 20) 11 -R 3 denotes R 1 and R 2, each water atom, a non-aromatic hydrocarbon radical or an acyl group, R 2 represents an alkylene radical and n represents an integer, present. A lubricant according to any one of claims 1-10, characterized in that a triaryl, trialkyl or trialkaryl phosphate is present. A lubricant according to any one of claims 1-11, characterized in that phenothiazine or an alkyl or halogen substitution product thereof and / or an aromatic amine are present. Request publications: