DE1936158A1 - Pentaerythritol esters useful as lubricants - Google Patents

Description

RtCHlSANWA-Ic.

DRJUR-DIVL-CHEM-WALTEReE ₁ I, ALFREDHOEPPENER DR. JUR. DIPL-CIcM. H.-J. WOLFF DR. JUR. HANS CHR. BEIL July 15th «969

623FRANKFURTAMMArN-KOCHST ....,., ..

ADElONSIBASSt M 1936 158

Our no. 15 701

Stauffer Chemical Company New. York, N.Y., V.St.A.

Pentaerythritol esters useful as lubricants

The present invention relates to synthetic esters useful as lubricants having a viscosity between about 5.0 and about 5.5 centistokes at 99 ° C and a minimum viscosity of 25 centistokes at 37.8 ° C and thereby are characterized in that they are essentially also Reaction product of pentaerythritol, aliphatic, monobasic acids with 3 to 9 carbon atoms and aliphatic dicarboxylic acids with 6 to 12 carbon atoms, with the monobasic acids totaling an average of 4 to 6 Having carbon atoms, the molar ratio of pentaerythritol to dicarboxylic acid is about 6: 1 to 0.5-1: 1 and the molar ratio of pentaerythritol to monobasic acid is about 4: 1 to about 1: 1.

The invention relates to pentaerythritol esters which are suitable for use as lubricants in plug-type engines. In particular, the invention relates to pentaerythritol esters which are resistant to oxidation at elevated temperatures, such as are required for use in aviation.

909886/1784

Although pentaerythritol due to its thermal and oxidativon Resistance has already been used to a large extent from polyol to make synthetic lubricants it was found that pentaerythritol esters much crystallize more easily than "those esters made by others Polyols such as trimethylolpropane and trimethylolethane are derived are. It therefore remained difficult to produce a pentaerythritol ester which, on the one hand, did not work at elevated temperatures evaporates and, on the other hand, does not crystallize at freezing temperatures. In order to meet these strict requirements and also to provide an ester which is not too volatile, one has in practice pentaerythritol ester with small amounts of up to about 25% by weight of esters of others Polyols mixed to prevent crystallization. However, this practice was not entirely satisfactory as they did the production and storage of two or more liquids, an additional mixing process and the application made a less stable ester required, which made full use of the stability of the pentaerythritol portion prevented.

It has now been found that the above requirements aviation can be met without mixing by providing a synthetic Bster suitable as a lubricant can, which consists essentially of the reaction product of pentaerythritol and at least one monobasic, straight-chain, aliphatic acid having 4 to 9 carbon atoms and an aliphatic dicarboxylic acid having 6 to 12 carbon atoms consists. The total amount of monobasic acids should have an average of 4 to 6 carbon atoms,

909886/1764

the molar ratio of pentaerythritol to dicarboxylic acid should be about 6: 1 to about 0.5-1 · «1" and. the molar ratio · from pentaerythritol to monobasic acid about 4: 1 to about Be 1: 1.

The esters of the present invention have a minimum viscosity at 37.8 ° O of 25 centistokes and a viscosity at 9.9 ° C - between about 5 and about 5.5 centistokes.

A mixture of monobasic acids is preferably used for optimum results. For example, although the total amount of Säurej required for the reaction with the pentaerythritol, at least about h mol caterpillar is per mole of pentaerythritol, should the molar ratio of a single aliphatic monobasic acid is preferably not more than about 3 moles per mole of pentaerythritol, and more preferably not greater than about 2.5 moles per mole of pentaerythritol. Although valeric acid in amounts of .bi-s ^; zuv: 3 moles per mole of pentaerythritol can be used, the G ₁ - and C _n - or higher monobasic acids should not be present individually in more than 2 _S 5 moles per mole of pentaerythritol for best results, since the C 1 acid in excess of that amount of volatility and the Go - * - .. and, higher. Acids in excess cause crystallization ,, ■

Examples of suitable monobasic acids used are butyric acid, valeric acid, caproic acid, oenanthic acid> caprylic acid and pelargonic acid.

909886/1784

Examples of - suitable aliphatic ^ dicarboxylic acids are Suberic acid, azelaic acid, sebacic acid and adipic acid.

Both the monobasic and the dicarboxylic acids are preferred uncompromised and saturated. Among the monobasic Acids are preferred acids having 4 to 7 carbon atoms, being a mixture of butyric acid and capron-s .'- iure is particularly preferred. The preferred dicarboxylic acid is azelaic acid.

The esters can be prepared by reacting the appropriate amounts of pentaerythritol, monobasic acid (s) and dicarboxylic acid with one another without the need for a preliminary catalyst, e.g. a heavy metal-containing catalyst, since these catalysts easily impair the stability of the esters. After completion of the reaction the mixture to a temperature and a pressure is _heated} sufficient Froio the acid and the polyol ester from the evaporate. The ester mixture is then washed with carbonate or water to remove any residual free acid.

The esters of the present invention can be used with various Additives are added5 to improve the durability serve against oxidation and corrosion. Examples of stabilizers that can be used are 5 ~ ethyl-10, lO-diphehylphenazasilane, phenothiariin and diarylamine, such as phenyl-naphthylamine and diphenylamine. If such Additives are discarded if they are added in a quantity that (iie is sufficient to produce the desired

BAD ORiGiNAi.

to surrender. Generally, an amount of from about 1 % to about 5 %, based on the weight of the lubricant, will suffice.

The following examples explain the invention and its preferred embodiments.

example 1

Manufacture of Pcntaerythrit azelate butyrate heptanoate (23 % azelaic acid)

In a reaction vessel surrounded by a wooden jacket and equipped with a thermometer, an Oldershaw distillation column, a water trap and a Dean-Stark tube, the following reactants including octane solvents were placed: 816 g (6MoI) pentaerythritol, 1045.5 g (11.38 mol + 5% excess) butyric acid, 1545 g (11.88 mol + 5 % excess) oenanthic acid, 133.2 g (O; 708 mol) azelaic acid and 250 ml isooctane as solvent. The reaction mixture was brought to a reflux temperature of about 150 ° C. After about 2/3 of the water had collected, most of the solvent was distilled off; whereby the vessel temperature rose to about 25O ° C, and allows a faster conversion. The product was obtained by first distilling the reaction mixture under reduced pressure at about 200 ° C. until all volatile constituents had been removed. The reaction vessel was then cooled to room temperature and the residue slowly became an equal volume of 2% sodium hydroxide solution at a temperature of about 60 ° C

BATH

909886/1764

and the mixture was stirred for 10 to 15 minutes. The oil layer was then decanted off, washed again with sodium hydroxide and then with water and treated with phosphoric acid until the oil was somewhat acidic. The oil was washed twice with water, dried under vacuum, and decolorized with 1% by weight of Norit A. and filtered through a layer Cclit the product was analyzed and _found; da / 3 it had the following physical properties after Havy type -i / 2 and Pratt and Whitney type 2:. '!.

Acid number - 0.04

Wt -.% OH- 0.01 mg KOH / g Viscosity at 3 ° C 7.8 29.71 it.

Viscosity at 99 ° C 5, -, 5 es.

Example 2

Manufacture of Pcntaorythrithcxavalor ^ t-'azclat (JO, 7% asela-inic acid)

Following the procedure of Example 1, 816 g (6 mol + 5 ^r i excess) of pentaerythritol, umgesetzt- 2388 g (23.4 mol + 5% About Shuf?) VaIoriansäure and 17S, 5 g (0.933 mole) of azelaic acid with each other. The product was analyzed and found to have the following Navy type physical properties. 1-1 / 2 and according to Pratt and Whitnay type 2: acid number 0.07

Wt% OH 0.02 to KOH / g

Viscosity at 37.8 ° C 28.8 es.

8AD ORIGINAL 909886/1764, ^ grrr,

Viscosity at 99 ° C 5 _; 45 it.

Specific gravity 1.0265.

Example 3

Manufacture of Pcntaorythrit azelate butyrate haptanoate (19.2 % azelaic acid)

Following the procedure of Example 1, 816 g (6 moles) of pentaerythritol, 1056 g (12 Hol + 5 % excess) butyric acid, 1560.0 pounds (12 moles + 5% excess) oenanthatesxuro and 113.7 g (Oj6o6 moles ) Azelaic acid reacted with one another ... The reaction product was analyzed and had the following properties according to Navy type 1-1 / 2 ur.d Pratt and Whitney type 2:. .

Acid number 0.00

Wt -.% OH 0.02 mn KOH / g

Viscosity at 37.8 ° C 27.8J + es.

Viscosity at 99 ° C 5.23 es.

Example 4

Manufacture of pentacrythritol valerate azclate (28.8 % azelaic acid) -

Following the procedure of Example 1, 815.0 g (β mol + 5 % excess) pentaerythritol, 2394.0 g (23.49 mol + 5% excess) valeric acid and f 64.7 g (O, S76: Mo1- ) Azelaic acid reacted with one another. The reaction product Mrdo is analyzed

BATH ORIGINAL

and had the following physical propertiesGii tiaeh Navy type T-1/2 and according to Pratt and Whitney type 2: acid number -...- -. * 0.06 V "■, - # OH ■ ■■■■" ■ ', 0.04 mg KOH / g;

Viscosity at 37.8 ⁰ C 27.5 it. Viscosity at 99 ° C 5.30 es.

The fact that the amount of dicarboxylic acids that is interwoven is critical is shown in the following example, in which 40 % azelaic acid gives an ester which at 99 ° C has a viscosity outside the above requirements. ■ "

Example ^_5; . "■ -. ■.."

Production v> n Pentaerythritazelat-valerate

(40 % Azelaic acid) -.- ^:

Following the procedure of Example 1, 816.0 g (6 mol) of pentaerythritol, 2322 g (22.74 mol + 5 % excess) valeric acid and 233.7 g (1.345 mol + 5 % excess) azelaic acid were reacted with one another. The reaction product was analyzed and had the following physical properties: acid number> 0.14 "- .. λ-

Weight-5i OH * 0.04 mg KQU / g

Viscosity at 37.8 ⁰ C 35.3 it. V viscosity at 99 ^Q C 6 _f 33 es. "

9806/1764

Claims (4)

Claims ι : ι1 ·) Pcntacrythritol esters, 'which are gecignef as Sehmirermi'ttei and a viscosity between about 5 ₇ 0 and about 5.5 Centi-. ■ stokos at 99 ° C and a minimum viscosity of 25 Ccntistokos ^{at 37.8 0 C, characterized} ; in that they wcsontlichon from the Reaktionsprodulit of pentaerythritol, aliphatischen- monobasic acids having 3 to 9 carbon atoms and aliphatic Oieax ^ bonsäurcn having 6 to 12 carbon · consist atoms, the average k einbasisehcn acids insgosamt Mr. 6 carbon atoms _having? the molar ratio of pentaerythritol to dicarboxylic acid is about 6: 1 to about "0; 5- ¹ : 1 and the molar ratio of pentaerythritol to cinbasic acid et * ra 4: 1, to about IM ₁ is 2. Pcntacrythi'itostor according to claim, Tj marked thereby, .daP he as a monobasic acid a mixture of Buttorsa'uro and ftnantäure o 3. Pcntaerythritol ester according to claim 1 or 2, characterized by gckennseichnot; that or as dic? .rbansäure contains azoleic acid, 4. pentaerythritol ester according to claim 1, characterized in that that it is the only monobasic acid containing valeric acid. · For: Stauffer Chemical Company L Lawyer