DE1104102B - Synthetic lubricants and lubricant additives - Google Patents

Description

Synthetic lubricants and lubricant additives The application aliphatic dicarboxylic acid ester on its own or as a component in natural or synthetic lubricating oils for special purposes, e.g. B. for the lubrication of turbines, Turboprop and turbo-jet engines, and as instrument lubricants, are known.

The use of esters is particularly advantageous because this as a result their polarity adhere better to metal surfaces and thus a stronger lubricant film form as mineral oils; Their admixture increases the wetting capacity and the high pressure lubricity of mineral oils.

It has been found that esters of aromatic polycarboxylic acids, in particular dicarboxylic acids, can also be used with particular advantage as base oils and as lubricant additives, which are obtained by transesterification of the residue obtained in the production of dimethyl terephthalate, in particular according to German patents 949 564, 969 994 and 1 041945, and consists of two- to three-ring and higher polycondensed meth.ylesters of aromatic polycarboxylic acids, in particular dicarboxylic acids, with primary aliphatic alcohols with straight or branched chain and 3 to 18 carbon atoms, preferably with 4 to 10 carbon atoms, alone or can be used in a mixture with one another are obtained.

The ester oils to be used in the present invention are described below produced as described, this production within the scope of the present Invention is not placed under protection: The distillation residue from the manufacture of dirnethyl terephthalate is topped off in a short-path distillation before the transesterification by using about 130 to 180 ° C is fed to a trickle evaporator, which is through a Z5-VA coil is heated to 260 to 280 ° C with circulating heating oil. The remaining topped off Distillation residue is mixed directly with the said primary aliphatic alcohols transesterified, while the distillate obtained with methanol, optionally under pressure, preferably at 25 atm and 230 to 250 ° C, post-esterified and then that therein Dimethyl terephthalate contained is precipitated, which is used for further work-up Added in the plant for the production of Dimethylterephtha.lat products can be. The filtrate is freed from methanol by distillation, and the remaining higher esters can then be transesterified in the manner described.

The products obtained in the distillation are transesterified in a manner known per se with the primary aliphatic alcohols in one apparatus, which consists of a reaction flask with attached packed column in which the lower-boiling alcohol is driven off with a little higher-boiling alcohol, compressed and is evaporated again in a second flask, in a second column the rest of the higher-boiling alcohol is condensed and demineralized via a return regulator Reaction flask is fed back. The lower boiling alcohol leaves over Head the second column and is caught in a template.

When using lower-boiling alcohols, their implementation is more difficult the reaction flask is stirred vigorously. During the transesterification reaction a weak stream of nitrogen is passed over the product. Appropriate works one with the addition of catalysts such as lead oxide, copper p-toluenesulfonate, butyl titanate or other basic catalysts.

Those from the topped off distillation residue and from the residues of the post-esterified distillate obtained by transesterification ester oils can alone or used as a mixture with one another.

The transesterified distillation residues obtained from the post-esterified distillate have excellent lubricity and can generally be used as base oils can be used. They have very low pour points, below -40 to -50 ° C and thus allow them to be used for the lubrication of refrigeration machines, for example.

By adding to ester oils, as they are topped off by transesterification Residue can be obtained, and becomes mineral or synthetic base oils their pour point lowered so that they can be used as pour point improvers.

The ester oils produced from the topped off residue by transesterification are to be used as lubricants for heavy loads or as high-pressure additives. Well-known additives, the base oils for this Make appropriate for the purpose are ineffective under some conditions or even act aggressively. To that extent it means a considerable step forward to be able to use base oils are not aggressive and have no corrosive effect.

The possible uses of the ester oils according to the invention are further increased by the fact that they can be mixed as required with hydrocarbons and mineral oils are. They can therefore also be used advantageously in a mixture with other lubricants use, for example with olefin polymers, the pour points of which they lower and the lubricity of which they improve, or with any natural or synthetically obtained lubricating oils. On the one hand to increase the viscosity, on the other hand but to obtain low pour points, mixtures of the higher esters are used prepared with the ester oils obtained from the topped off residue are recommended. Such mixtures can be used and guaranteed at low and high temperatures hence reliable lubrication.

Example 1 An ester oil with the following key figures: Pour point. . . . . . . . . . . . . . -43 ° C Flash point. . . . . . . . . . . . . 245 ° C Specific weight ...... 1.009 viscosity at 20 ° C. . . . . . . . . . . 438 cSt = 57.8 ° E at 50 ° C. . . . . . . . . . . ... 65.5 cSt = 8.6 ° E at 70 ° C. . . . . . . . . . . . . . 27.3 cSt = 3.7 ° E Directional constant in ..... 3.89 Viscosity pole height Wp ... 2.62 is prepared in the manner described below: 500 g of higher esters from the distillate of the DMT °: residue (AN = 4.55; VZ = 502) are mixed with 750 g of 2-ethylhexanol- (1) in the presence of 2.5 g ( 0.2%) lead oxide interesterified. A gentle stream of nitrogen is passed over the product during the reaction. The elimination of methanol begins at a reaction temperature of 160.degree. C. and is complete after 180 minutes (140g CH30H), the bottom temperature rising to 220.degree. To be on the safe side, 0.05% Pb0 is added and the reaction is maintained at 225 ° C. for a further hour. The excess 2-ethylhexanol is then earth-distilled up to a bottom temperature of 200 ° C. at 10 mm Hg. 172 g of ethylhexanol are recovered in this way. The reaction product now has an acid number of 0.6 and is heated for 1 hour at 80 to 90 ° C with 0.5% activated charcoal and fuller's earth in vacuo for cleaning. It is then refined with a 50% excess of n / 10-KOH for 1 hour at 80 ° C., and the deacidified product is deodorized at 140 ° C. and 10 mm Hg by blowing steam through it.

The ester oil obtained can because of its low pour point and high flash point both as a lubricating oil or in a mixture with other oils as a pour point depressant will. A 10% addition of this oil to another by transesterification of the topped off Residue formed @ `) DMT = dimethyl therephthalate. Ester oil (Example 2) results a lowering of the pour point by 19 ° C.

Example 2 321 g of ester oil (SZ = 38.5; VN = 261.5) which is acid-free after refining twice with KOH and subsequent bleaching, and the key figures Pour point. . . . . . . . . . . . . . -I-6 ° C Flash point. . . . . . . . . . . . . 269 ° C Specific gravity ...... 1.068 viscosity at 50 ° C. . . . . . . . . . . . . . 1692.7 cSt = 227 ° E at 70 ° C. . . . . . . . . . . . . . 417.9 cSt = 55.2 ° E Directional constant m ..... 3.46 Viscosity pole height Wp ... 2.9 possesses, is obtained in the following manner: 655 g of topped DMT residue are removed with an alkali. 360 g of KOH and 750 cc of water (10% excess) are saponified for 8 hours under reflux and the free acids are prepared from the potassium salts with 900 cc of HCl (1: 1). After neutral washing and drying, 550g are produced (SZ = 466). 200 g of these acids are esterified with 387 g of 2-ethylhexanol- (1) for 36 hours in the apparatus described without a catalyst, 34 g of water being formed.

The 01 can because of its high viscosity either alone or in admixture with other oils, advantageously having a Esteröl as described in Example 1, are used to lower the pour point and the viscosity of the high-pressure lubrication. An addition of 10% of the ester oil according to Example 1 lowers the pour point to -13 ° C.

Example 3 An ester oil produced according to Examples 1 and 2 using alcohols with 8 and 10 carbon atoms is used as the base oil and gives the following test result: 1. Corrosion and oxidation behavior according to FTMS 791-5308.4 Weight Test panels loss of appearance mg / cm4 Stole . . . . . . . . . . practically unchanged at 0.01 Copper ........ multicolored, predominantly 0.13 silvery Silver ......... gray tarnished 0.01 AlMgSi ....... practically unchanged 0.03 Pure aluminum practically unchanged at 0.03 Evaporation loss ...... 0.35 percent by weight Eliminations ........... none Change of NZ. . . . . . . . . practically zero Change in viscosity ... -F-12.810 / 0 z. Load capacity on the four-ball apparatus VKA welding load .... 170 to 180 kg (for comparison mineral base oil.................. 130 to 140 kg) with the following key figures: pour point -10 ° C; Flash point 274 ° C; Viscosity 16.32 ° E / 50 ° C; 2.78 ° E / 100 ° C. 3. Load capacity on the Almen-Wieland machine a) Contact pressure: 1750 kg for normal running; b) Endurance run with 1000 kg load only 78 kg frictional force at 5000 U; Abrasion: 0.033 mm; Appearance of the test bearing: Very smooth, narrow running surface, practically completely free of grooves, mostly glossy, very slightly discolored gray.

Example 4 The ester oil mentioned in Example 3 was mixed with the mineral Base oil of example 3, item 2 mixed and for its effect as a pour point improver examined. If the base oil has a pour point of -10 ° C, mixtures 20:80 or 10:90 ester oil at -30 ° C still clearly liquid, while mixtures up to 90:10 ester oil are likely to be increasingly cloudy, but do not freeze.

Claims (1)

PATENT CLAIM: Use of transesterification products in manufacturing of dimethyl terephthalate resulting distillation residue with primary aliphatic Alcohols with straight or branched chain and 3 to 18 carbon atoms, preferably with 4 to 10 carbon atoms, alone or in a mixture with one another, as a lubricant and additive to lubricants based on minerals or synthetic oils.