DE887986C - lubricant - Google Patents

Description

Lubricants This invention relates to synthetic lubricants Esters.

It has been found that complex esters of the general formula RI-0 0 C-R2-C O 0-R3-0 0 C-R4-C O 0 Rä, in which R1 and R5 are aliphatic alcohol or ether alcohol residues, R2 and R4 denote hydrocarbon radicals of aliphatic dicarboxylic acids and R3 a hydrocarbon radical or the radical of an oxygen-containing hydrocarbon of a glycol or polyglycol, all radicals R1 to R5 being saturated and R3 is preferably a polyglycol radical, mixed with a liquid, aliphatic diester of a saturated aliphatic dicarboxylic acid lubricant with particularly favorable properties.

Ongoing investigations with aircraft engines, namely those that exposed to high temperatures, such as nozzle-type combustion turbines Propellers, showed that there is an urgent need for a lubricant, that can cope with the unusually high demands. In addition to good lubricity the lubricant should have a low pour point and a high viscosity index (or low A. S. T. M. slope) (under A. S. T.12. slope is the slope to understand the A. S. T. M. viscosity temperature curve) in order to achieve sufficiently high viscosity at the working temperatures as well as a low viscosity at start temperatures to own.

A typical mineral aircraft lubricating oil has fungal properties Kinematic viscosity at 99 ° C. s .... 9 38 ° c. s .... 67.5 ASTM-I slope at 38 to 99 ° ..... o, 688 Flash point ........................ 213 ' Pour point ......................... -23 ° 1. AE experimental gearbox for load limit value ........................ 22.68 kg es = Centistolces These properties do not meet the high requirements of aircraft turbines. The development of significantly improved mineral base oils is not likely. Therefore, the experimental work was concerned with synthetic esters. Of the various classes of esters, those mentioned above prove to be useful.

The physical properties of these esters affect the viscosity and determine the pour point are largely a function of the chain length and the configuration of the complex molecule. The lower representatives of this range are relatively light, the higher waxy solid. These are also useful under certain circumstances. Esters, the properties of which they act as lubricants make suitable for multiple uses have from about 20 to about zoo carbon atoms in the molecule, suitably about 3o to about 6o carbon atoms. One more or less uniform distribution of the carbon atoms on the three components is advisable, but not essential. Suitable starting materials are polyglycols with C4 to C24, Alcohols with Cl to C, and dicarboxylic acids with C6 to C2o. Generally be proportionate straight-chain substances such as polyethylene glycols and acids of the polymethylene succinic acid type, such as adipic acid or sebacic acid are preferred. Some side chains are desirable to give low pour points; so 2-ethylhexanol or isooctanol are preferred Alcohols for the radicals R1 and R5. The R1 and RS positions do not need to be included to be occupied by the same radical; admittedly, this simplifies production. For the composition of the product taking into account the starting materials to say that the different R radicals substances of different composition can be, such as polyglycol fractions that contain several specific polyglycols, Mixtures of two or more dibasic acids and fractions of aliphatic Alcohols with a selective boiling range, for example the alcohol fractions of the oxo synthesis, which contain several alcohols. In this case the general formula gives only one medium composition again; the individual molecules of the product can largely vary. If mixtures or fractions of the type mentioned are used, its composition is appropriately adjusted precisely so that it can be used for different batches reproducible values can be obtained.

In the group of esters proposed here, those of octyl or nonyl alcohols, adipic or sebacic acid and triethylene or tetraethylene glycols or their closest homologues derived products have a special position; their salient physical properties are of the same order of magnitude like that of the aircraft oil in question. When selected, shows it turns out that complex esters with excellent viscosity behavior or excellent Viscosity index can be easily manufactured; but it is very difficult to find products that have both properties at the same time. Most complex with the required viscosity generally have too high an A. S. T. M. propensity, while which with a favorable A. S. T. M. tendency regularly have too high a viscosity.

Aliphatic esters of aliphatic dicarboxylic acids are useful as lubricants known for various purposes; they have low viscosity and low viscosity index (high A. S. T. M. tendency) and are therefore used as plug-in turbine lubricants mentioned type completely unsuitable.

It has now been found that these diesters are particularly effective Blending of complex esters are suitable and that these blends have better properties than the most complex themselves have. In other words, if a diester lower Viscosity and high A. S. T. M. tendency with a complex ester of high viscosity and lower A. S. T. M. propensity, the viscosity of the complex ester becomes decreased more than the A. S. T. M. tendency is increased. It was also found that the lubricity, the load limit and other essential properties the mixing does not differ significantly from those of the complex esters themselves. The mixtures can be made by separating the two the manufactured ingredients, the diester and the complex ester, physically mixes or in one or more stages, optionally in the presence of an esterification catalyst, a dicarboxylic acid or a corresponding acid-forming compound, a glycol (or polyglycol) or a glycol-forming compound and an alcohol or a alcohol-forming compound is reacted with one another in stoichiometric proportions in such a way that that the reaction product of a complex ester of the formula and a Alcohol diester consists of dibasic acid.

When the mixture is made by the second method, i.e. H. produced by reaction mixtures or fractions can serve as reactants; preferably but acids, alcohols and glycols as such in the presence of an esterification catalyst used. Other known esterification methods can also be used, for example with exclusion a catalyst, work; for example with the conversion of alkali metal salts of the acids with halogen derivatives of alcohol and glycol or by reacting the Acid chlorides with Allia metal derivatives of alcohol and glycol.

The starting materials for the preparation of the complex ester are 2 moles of acid, 2 moles of alcohol and z moles of glycol. A further n moles of acid and 2 n moles of alcohol are used to produce the mixture. used when n: r is the desired molar ratio of diester to complex ester in the mixture. The total components of the mixing are thus 2 -f n mole of acid, 2 -f 2 n moles of alcohol, and z moles of glycol.

The starting materials can be reacted with one another in various ways will. Examples are: a) a stage; all ingredients are refluxed to Brought reaction; b) Formation of the glycol half ester. Glycol is initially used with excess Acid esterified; the mixture of glycol half-ester and free acid is then with Alcohol converted to a mixture of complex ester and diester; c) formation of a Alcohol half ester; Alcohol and acid are reacted under reflux and form a mixture of diester and alcohol half-ester, which is then refluxed with Glycol is implemented.

Another method consists in the alkyl exchange, with complex esters by reacting diesters with glycols under reflux in stoichiometric amounts in the presence of an esterification catalyst in the sense of the equation getting produced. 2 moles of diester are brought into action for 1 mole of glycol by simply reacting the reactants under reflux in the presence of a catalyst and distilling off the alcohol formed in this way. The conditions and restrictions which preferably apply to the ester mixtures prepared in this way correspond to those indicated above.

Some advantages of the lubricants according to the invention are summarized in Table i. The diesters used for this come from the trade. The complex esters were produced by the glycol half ester method, the glycol half ester being formed in a first step from 1 mol of glycol and Z mol of a dibasic acid, which is neutralized with 2 mol of a monohydric alcohol in a second step. The table shows physical and other properties of the various compounds. Table i No. i 2 3 4 6 7 Most complex mix. Most complex Min. From 2-ethyl complex ester of No. 4 of No. 3 -f- Aviation hexanol from No. 3 to 6o diesters + diesters Ingredients of vegetable oil Debanyl- sebacic acid Dinonylsebacat hours octyl- of No. 6 sebacat (6o: 40 vol.) (for Ver and Polyglycol o, on Vers.- sebacat (60: 40 V01.) equal) Zoo = 0.1 °: o + ° '3 @ gear, + o, 3 °, ...' a anti- Antioxidant *) Antioxidant 9o, C Oxyd Xin. Visc. cs 99 ° ...........: ... 9, o 4.61 ii, io 7.98 7.95 3.93 8.14 38 ° ............... 67.5 i958 5764 38.84 39i6 i534 3942 -40 ° .... - .......... 2.22o 17.694 8159 8i49 1.28o 8, i40 - 40 ° (extrapolated) .. 2.61o 8.700 5.900 6.400 i, 5oo 5.800 ASTM slope 38 to 99 ° ........ o, 688 o, 661 0553 0590 0595 o, 667 ö, 586 - 4o to 99 ° ........ o, 652 0.583 o, 607 o, 607 o, 658 o, 603 Flash point, ° C .... 2i3 218 232 224 232 2i0 221 Pour point, ° C ...... -23 -51 -51 <- 40 <- 54 -45.5 IAE Vers. Gearbox, Load limit, kg 23 25 68 43 - 28.6 50 Durability test, kg ... z3 18 36 36 - 23 36 Hrs. 170 68 20 - 130 38 and 25 (two attempts) Initial acidity mg KOH / g .... ... 2.0 4.7 4.0-3.9 5.1 End acidity mg KOH / g 2.05 5.6 3.7-2.9 4.7 Test time / hour ..... 200 8o 210 - 136 74 Corrosion test **) ..... pos. neg. neg. neg. neg. neg. *) Antioxidants: 2,6-di-tert-butyl-p-cresol. **) 100 hours at 49 ° and 100 °; 'o RH against sandblown soft steel. A comparison of these mixtures with known mineral oil shows that they have high quality properties which combine the favorable properties of both components. With a lower viscosity reduction at 99 °, the viscosity values at -40 'are more than halved. The ASTM slope is only increased by about 0.02. Furthermore, the results of the test gearbox test are remarkably favorable.

Table i thus teaches that mixing of servers with complex esters a remarkable adjustment in viscosity without any corresponding deleterious effect the viscosity index, pour point or lubricating behavior. The viscosity relationships Table 2, 3 and 4 express the mixes particularly clearly.

Table 2 shows the properties of the mixtures of several diesters with a complex ester, which was prepared by the glycol half-ester method, from nonyl alcohol, sebacic acid and polyglycol Zoo. Table 2 Kinematic viscosity cs ASTM pour point Components 990 380 - 400 _ slope 0 C (extrapol.) 38 to 99 ' Most complex. . . . . . . . . . . . . 13.99 8o, 65. = 6.80o 0.544 -43 2. Dioctylseb .................... 3.26 12.35 1.29o 0.7o6 <- 51 3. Dinonylseb. ................. 4.76 19.4 2.400 o, 639 <- 51 4. Dicaprylseb. . . . . . . . . . . . . . . . . 3.53 14.05-0704 -23 Mixtures by volume 6o 0/0 1 -I- 40 0/0 3. . . .-. . . . . . . . . . 9.04 49.6 = 2, = o0 0.6o2 <- 45.5 6o 0/0 1 + 40% 3. . . . . . . . . . . . . . . 8.97 4597 7.300 o, 585 -48 70 0 / a 1 -f- 30 0/0 2. . . . . . . . . . . . . . . 9, o1 46, o 7.350 0.584 <- 51 70 0/0 1 -f- 30 0/0 2. . . . . . . . . . . . . . 9.24 .46.79 7.60o 0.577 <- 51 70 0/0 1 + 30 0/0 4. . . . . . . . . . . . . . 9.07 4641 756o 0.583 -48 The low temperature viscosity of the various mixtures according to Table 2 is noticeably more favorable than that of the complex ester; the ASTM slope is not changed accordingly; the pour points are favorable. Tables 3 and 4 show the properties of mixtures of complex esters and diesters. For Table 3, the complex esters from Table 2 (nonyl alcohol, sebacic acid and polyglycol Zoo) and di-2-ethylhexyl sebacate were used. Table 3 Volume percentage Most complex ...... ioo 70 65 6o 55 50 40 35 0 Volume percentage Diester ............ - 30 35 40 45 50 6o 65 Zoo Kinemat. Viscosity cs 99 0 . . . . ... . . . . . . . . 13.99 9.24 - 8.56 7.96 7.36 6.55 5.93 5.18 3.26 38 ° ............... 8o, 65 46.7 9 42.25 38.68 3448 29.82 25.98 21.94 12.35 -400. . . . . . . . . . . . . . . -, - 10.075 8.3o8 6.743 6396 3.80o 2.662 1.367 ASTM slope 38 to 99 ° ..... .... 0.544 0 577 0.582 0.591 0596 o, o 6o9, 617 o, 634 0,7o6 For Table 4, dinonyl sebacate and a complex ester were used which had been prepared from sebacic acid, polyglycol 2oo and 2-ethylhexanol by the glycol half-ester method.

The manufacturing process for this complex ester is not per se Part of the present invention; for the sake of completeness, however, a description should be provided the preparation of this particular complex ester are then given.

i1 kg of sebacic acid, 4.9 kg of polyglycol Zoo, 1.89 l of toluene as a dehydrating agent and 0.12 kg of sodium bisulfate as an esterification catalyst were placed in a large Pyrex flask brought in. The mixture was heated for 25o minutes at a temperature increasing from 12o to 173 ° stingy under reflux; up to the end of the reaction, 10o0 / 0 of the calculated amount of water was removed; the final acidity was 182 mg K O H / g.

8.43 kg of 2-ethylhexanol were then entered; the whole was refluxed for a further 320 minutes at a temperature increasing from 11o to 1g8 °; the final acidity was 1.75 mg KOH / g. The product was then treated in a vacuum up to 178 ° steam temperature at 0.2 mm Hg pressure. Table 4 Volume percent complex ester o 1o. 20 30 40 50 55 6o 68 Zoo Volume percent diester ...... 100 go 8o 7o 6o 50 45 40 32 0 Kinemat. Viscosity cs at 9g ° ................. 4.61 5.05 5.55 6, o1 6.5ä 7yög 7.62 7.98 8.45 11.10 - 38 0 ................: -1 9 , 58 21.66 24.31 26.77 30, = 7 3346 3658 3884 4157 5764 - -40 °. . . . . . . . . . . . . . 2.22o 2.788. . 31292 . 4.019 2 5, = 34 6.354 7304 8.159 9428 17694 ASTM slope 38-99 ° ............... o, 661 o, 643 o, 630 o, 618 o, 617 0,605 0, 596 0, 590 o583 0.553 If the mixture of complex ester and diester is produced by reaction, it is advisable to produce this via the glycol half-ester or in a single-stage reaction. Tables 5 and 6 show comparative results of these methods applied to a separately prepared blend.

Table 5 shows duplicate tests for both reactions with 2 moles of 2-ethylhexanol, 2 moles of nonanol, 3 moles of sebacic acid and 1 mole of polyglycol Zoo. These are compared with a mixture of di-2-ethylhexyl sebacate and a complex ester obtained from nonanol, sebacic acid and polyglycol Zoo using the glycol half-ester method. Table 5 Mixing i stage i stage glycol glycol complex half-semester -t- diester 1 Theoretical complex ester salary ..................... 64 64 64 64 65 Kinemat. Viscosity cs at 9g ............. . . . . . . . . 8.6o 8.71 g, oo 8.74 8.56 - 38 °. . . . . . ... ... ... . . . . . 4332 4392 4554 4396 42.25 - -40 ° ........... .... 10.159 10.373 cloudy 1o, 884 10.075 ASTM slope 38 to 9g °. ... .... ... .... 0.587 0.585 o, 581 o, 585 0.582 . Pour point ° C ............... below - 51 below - 51 below - 51 below - 51 -51 The table teaches that the properties of the mixtures obtained by reaction can be compared well with those of the mixtures prepared separately.

Table 6 shows similar results obtained with several complex esters and complex ester blends. For the mixtures 1, 2, 3, 4, 6, 7, g and To, alcohol and acid were used in sufficient excess and thus resulted in a mixture of the composition shown. Table 6 Mixing II 2 I 3 I 4 5 I 6 I 7 I 8 9 I io I 11 Components. . . . . . . . . . Nonanol 6o0 / 0 Nonanol 7-% Nonanol 700/0 Sebacic acid com- 2-ethylhexanol com- capryl alcohol com- Polyglycol 200 plex »A« sebacic acid plex »A« sebacic acid plex »A« 40% polyglycol 200 30 () / o polyglycol 200 30% DNS DOS DCS Method. . . . . . . . . . . . . . . Glycol- 1 I Glycol- GHE 1 ver GHE I ver '/ 2 ester stage stage 1/2 ester mix stage mix stage mix Theoretical percentage Complex ester content ... 73 73 64 64 6o 79 79 70 81 81 70 Kinemat. Viscosity cs at 99 ° ............. 12.11 1 0.93 9.65 I0.17 8.97 1 0.81 io, ir 9.24 1 1.26 1 2.12 9, 0 7 - 38 ° .............. 7I 6I 8, 25 52.12 53.71 4597 56.33 53.54 46.79 6 1 , 76 69.11 46.41 - -400. . . . . . . . . . - 24.485 16.2o7 17.400 impossible 17,495 15,390 impossible 21,148 impossible -not possible. ASTM slope 38 to 99 °. . . . . . . . . . 0.574 0.576 o, 586 o 0.572, 0.559 585 0.573 0577 o, 566 0,565 0, 583 Pour point ° C. . . . . . . . . -48 <-51 <-51 -45 -48 <-51 -45 <-51 -45 -45 -48 Complex ## A «made from nonanol, sebacic acid and polyglycol zoo via glycol half-esters. DNA - Dinonyl Sebacate. DOS - Di-2-ethylhexyl sebacate. DCS - dicapryl sebacate. The comparative comparison of the various mixtures makes it clear that their properties such as viscosity, viscosity index (ASTM tendency) and pour point are all favorable and are of the same order of magnitude. It often turns out that mixtures of theoretically the same composition, obtained on the one hand by reaction and on the other hand by mixing the components, have noticeably different viscosity properties at low temperatures above the pour point, insofar as the former flow well with a measurable viscosity, the latter hardly flow and the viscosity of which is often not measurable.

From the preceding description and the tables it can be seen that the mixtures according to the invention have favorable properties as lubricants and have advantages over each of their constituent parts. Of course, mixtures of more than two components can also be produced in order to meet special requirements, ie one or more complex esters can be blended with one or more diesters. In general, mixtures with up to 20% diester suggest favorable behavior as an aircraft turbine lubricant (depending on the constituents used); Mixtures which contain the complex ester as the main component regularly have better exposure limits. Other high diester blends are valuable as instrument oils and for similar purposes. If the mixtures are to be used at high temperatures, it is advisable to add a small amount of an antioxidant. For this you can use the usual antioxidants in suitable amounts of up to a few percent. It is preferred to use those of the phenol type, for example trialkylphenols such as 2,6-di-tert-butyl-4-methylphenol, in an amount of less than 1 percent by weight, about 0.1 to 0.5% .

In addition to the possibility of producing a mixture of any The invention provides viscosity between the viscosity values of the constituents the technical advantage that when ordering a complex ester lubricant with certain behavior, the proportions of the mixing so coordinated can be that the required properties are achieved exactly, even if there are differences between the individual batches of the same complex ester. For example, if a lubricant from io c. see at 9g ° is required and this Request met by an unmixed complex ester of this viscosity there may be discrepancies between different ones produced in the same way Batches exist. If a complex ester with a viscosity of over io c. s. used this can be done by blending with a suitable diester in the relevant Quantity ratio based on a mixing of io c. s. to be adjusted.

Claims (7)

PATENT CLAIMS: i. Lubricants, characterized in that these consist of a complex ester and a diester, the complex ester being the general Formula Rl-OOC-R2-COO-R3-OOC-R4-COOR5 has, in which R1 and R5 aliphatic alcohol or ether alcohol residues, R2 and R4 hydrocarbon radicals of aliphatic dicarboxylic acids and R3 is a hydrocarbon radical or a radical of an oxygen-containing one Is hydrocarbon, a glycol or polyglycol, all radicals R1 to R5 are saturated, the number of carbon atoms in the molecule is about 20 to 100 and the diester is a liquid, aliphatic diester of a saturated aliphatic Is dicarboxylic acid. 2. Lubricant according to claim i, characterized in that the complex ester contains 3o to 6o carbon atoms in the molecule. 3. Lubricants according to claims 1 and 2, characterized in that the radical R3 is a polyglycol radical is. 4. Lubricant according to claim i to 3, characterized in that R1 and R5 alkyl groups from Cl to C12, R2 and R4 aliphatic hydrocarbon radicals from C6 to C2) and R3 is a C4 to C24 polyglycol radical or mixtures thereof Groups and radicals whose mean carbon numbers are in the specified range lie. 5. Lubricant according to claim i to 4, characterized in that the The glycol component is a polyethylene glycol, preferably tri- and / or tetraethylene glycol is. 6. Lubricant according to claim i to 5, characterized in that the acid component of the complex ester is a polymethylene succinic acid, preferably adipic or sebacic acid is. 7. Lubricant according to Claims 1 to 6, characterized in that the alcohol component of the complex ester is a branched-chain alcohol, preferably 2-ethylhexanol, isooctanol, a nonanol or an alcohol fraction from the oxo synthesis. B. Lubricant according to claim 1 to 7, characterized in that the diester is an ester of an aliphatic alcohol from Cl to C12 and an aliphatic dicarboxylic acid from C 1 to C20. G. Lubricant according to Claims 1 to 8, characterized in that the acid is a polymethylene succinic acid, preferably adipic or sebacic acid. ok Lubricant according to Claims i to g, characterized in that the alcohol is a branched-chain alcohol, preferably 2-ethylhexanol, isooctanol, a nonanol or an alcohol fraction from the oxo synthesis. ii. Lubricants according to claims i to io, characterized in that they contain di-2-ethylhexyl sebacate, dilsooctyl sebacate or dinonyl sebacate as diesters. 12. Lubricant according to claim i to 7, characterized in that the complex ester was obtained by reacting 2-ethylhexanol or nonanol with sebacic acid and a polyethylene glycol fraction consisting mainly of tetraethylene glycol. 13. Lubricant according to claim i to i2, characterized in that they contain the complex ester as the main component, preferably at 6o to 7o percent by volume and the diester at 40 to 30 percent by volume. 14. Lubricant according to claim i to 13, characterized in that they also contain an antioxidant in a small amount, up to a few percent. 15- lubricant according to claims i to 14, characterized in that they contain trialkylphenol as an antioxidant in an amount of less than i%, preferably 0.1 to 0.5 % by weight. 16. Lubricant according to claim i to 15, characterized in that this 2, 6-di-tert-butylq. - contain methylphenol as an antioxidant. 17. Process for the preparation of lubricants according to claim i to 16, characterized in that one or more aliphatic glycols, polyglycols, one or more aliphatic glycols, polyglycols, an aliphatic dicarboxylic acid or acids or analogous acid-forming compounds, in one or more stages, optionally in the presence of an esterification catalyst or polyglycols or an analogous glycol-forming compound and one or more aliphatic alcohols or analogous alcohol-forming compounds in a stoichiometric ratio, so that a mixture of a complex ester of the general formula R '@ OOC-R2 - COO-R3-OOC-R4- COOR5 and the diester or diesters of alcohol and dicarboxylic acid or acids is formed. 18. The method according to claim 17, characterized in that acid, glycol or polyglycol and alcohol are used as starting materials. ig. Process according to claims 17 and 18, characterized in that acid, glycol or polyglycol and alcohol are reacted under reflux in the presence of an esterification catalyst, the water of reaction being removed. 2o. Process according to Claims 17 to ig, characterized in that the glycol and acid are esterified in a first stage to form a mixture of glycol half-ester and free acid and the mixture is then esterified with the alcohol. 21. The method according to claim 17 and 18, characterized in that the alcohol and acid are esterified in a first stage to a mixture of diester and alcohol half-ester and the mixture is then esterified with the glycol. 22. The method according to claim 17 to 21, characterized in that the molar ratio of acid, alcohol and glycol is set to 2 -f- n : 2 + 2 n : i, where n: i is the molar ratio of the diester to the complex ester in the mixture and n is chosen so that the mixture contains a smaller proportion of the volume of the diester.