US3449459A - Lubricating compositions for compression refrigerators - Google Patents

Description

United States 3,449,459 LUBRICATING COMPOSITIONS FOR COMPRESSION REFRIGERATORS Michel Asfazadourian, Robert Muths, and Marcel Prillieux, Mont-Saint-Aignan, France, assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Nov. 2, 1966, Ser. No. 591,407 Int. Cl. C07c /02; C09k 3/02 US. Cl. 260-671 7 Claims ABSTRACT OF THE DISCLOSURE The present invention is concerned with synthetic lubricants intended for the lubrication of compression refrigeration apparatus. These lubricating compositions are characterised by their miscibility with halogenated refrigerating fluids such as the fluorochlorinated hydrocarbons of the Freon type.

Synthetic oils obtained by the fractional distillation of the alkylation products of benzene by olefins, in the presence of a Friedel and Crafts catalyst are known; these oils are in fact miscible with refrigerating liquids of the Freon type down to very low temperatures.

The applicants have discovered that alkylated aromatic hydrocarbons, when subjected to superalkylation, furnish products that can be used as lubricating oils for compression refrigerating apparatus.

The alkylaromatic hydrocarbons intended to be superalkylated according to the invention are those having from 1 to 5, and preferably 2 to 3 straight or branched aliphatic chains. Each chain preferably has from 1 to 15 carbon atoms.

Suitable examples are methylethylbenzene, dimethylethylbenzene, trimethylbenzene, tetramethylbenzene, or mixtures of these substances, preferably:

The product known in the trade by the name of Solvesso 100, i.e. a mixture containing 92% methylethylbenzene and tetramethylbenzene and having as its characteristics:

Density 0.872 ASTM distillation:

Initial point C 158 50% distilled C 163 Final point C 171 Mean molecular weight 120 The product known in the trade as Solvesso 150, a mixture containing 70% dimethylethylbenzene and tetramethylbenzene and having the following characteristics:

Density 0.892 ASTM distillation:

. Initial point C 187 50% distilled C 193 Final point C 212 Mean molecular Weight a- 135 The petroleum fraction distilling between 170 C. and 325 C., 50% distilled at 181 C., with a mean molecular weight of 136 and a density of 0.905.

atent O "ice According to the invention this superalkylation takes place in the presence of a classic alkyla-tion catalyst with olefin polymers, for example a trimer, tetramer or pentamer of propylene and for preference those complying with the following characteristics:

Propylene trimer:

Density 0.740 ASTM distillation:

Initial point C Final point C Mean molecular weight 127 Propylene tetramer:

Density 0.777 ASTM distillation:

Initial point C 183 50% distilled C..- 188 Final point C 222 Mean molecular weight 172 Propylene pentamer:

Density 0.802 ASTM distillation:

Initial point C 269 50% distilled C 271 Final point C 303 Mean molecular weight 245 Suitable alkylation catalysts are sulphuric acid or acids of the Lewis type such as AlCl or BF Alkylation is performed at a temperature of 0 to 60 C. and preferably at about 40 C. the weight ratio aromatic hydrocarbon/ olefin polymer being between 7/1 and 1/ 1, and preferably between 3/1 and 5/ 1. The catalyst represents 3 to 10% and preferably 5 to 6% by weight of olefin. The operation takes about one hour.

The lubricating oils according to the invention make it possible to prepare mixtures with halogenated refrigerating fluids, such as the fluorochlorinated hydrocarbons of the Freon type, the proportion of lubricant being preferably 1 to 10% by Weight of the mixture.

The following example illustrates the invention.

EXAMPLE Solvesso 100 and Solvesso were superalkylated with propylene tetriamer, these substances having the properties mentioned previously. This superalkylation was performed under the following conditions:

Temperature-40 C.

Weight ratio Solvesso/tetrapropylene-5/ 1. Catalyst AlCl 6% by weight of tetrapropylene. Time-1 hour.

The superalkylated Solvesso 100 had the following characteristics Density 0.884 Distillation C 305/350 and the superalkylated Solvesso 150:

Density 0.935 Distillation C 330 Two mixtures M1 and M2 were prepared. Mixture M1 comprised: 35% by volume of superalkylated Solvesso 100; and 65% by volume of superalkylated Solvesso 150. Mixture M2 comprised: 40% by volume superalkylated Solvesso 100; and 60% by volume superalkylated Solvesso 150.

The characteristics of mixtures M1 and M2 were determined according to the following methods:

Flash point, open vessel NFT 60103 Density NFT 60-101 Cloud point ASTM D 9757 Aniline point ASTM D 611-63T Viscosity NFT 60-100 The following results were obtained:

Density, 15 C 0. 906 0. 896 Flash point open vessel 168 160 Viscosity in centistokes at 37.8 0. (100 F.) 40. 21. 9 ASTM colour 3- Flocculation point C. 60 37 Cloud point, C -33 36 Aniline point, C 35 32. 5

1 This temperature is that at which precipitation by flocculation takes place in a mixture of lubricating oil and 90% refrigerating fluid. It is ascertained under the following conditions: 1 cc. of the oil to be tested is placed in a thick glass tube; it is then heated to 120 C. and dry nitrogen is injected through the sample for about 10 minutes. The tube is then allowed to cool to the ambient temperature and is placed in a cooling bath, whose temperature is higher by about 8.5 C. than the assumed flocculation point. There are then added 9 cc. Freon 12 (OClQFZ) and the tube is closed, After checking the homogeneity of the mixture, the tube is put back in the cooling bath and the temperature is lowered by 2.8 C. in 4 minutes and the appearance of the mixture is examined after 15 minutes at this temperature. The process is continued as long as is necessary by lowering the temperature of the bath by fractions of 28 C. until the presence is noted of a definite precipitate in the sample. The corresponding temperature of the bath is that of the flocculation point.

It thus appears that the viscosity and the flocculation point can be ascertained by varying the relative proportions of the different superalkylated Solvessos used. The mixture M1 furnishes a particularly interesting flocculation point.

It is obvious that the present invention has been described purely by way of explanation and in no sense restrictively and that any modifications may be made to it without departing from its scope.

We claim:

1. A process for preparing a hydrocarbon lubricating oil that is miscible with a fluorochlorinated hydrocarbon refrigerant at low temperatures which comprises alkylating a mixture of aromatic hydrocarbons consisting predominantly of at least two diiferent hydrocarbons from the group consisting of methyl ethyl benzene, dimethyl ethyl benzene, trimethyl benzene, and tetrainethyl benzene, with a polymer of propylene having 9 to 15 carbon atoms, in the presence of an alkylation catalyst, the weight ratio of the said mixture of aromatic hydrocarbons to propylene polymer being in the range of from 1:1 to 7: 1.

2. A process as defined by claim 1 in which the alkyl aromatic hydrocarbon mixture is a petroleum fraction distilling between and 325 C., 50% distilling at 180 C., and of mean molecular weight 136 and density 0.905.

3. A process as defined by claim 1 wherein the catalyst is selected from the group: sulphuric acid and a Lewis acid.

4. A process as defined by claim 1 wherein said weight ratio is within the range of 3:1 to 5:1.

5. A process as defined by claim 1 wherein said mixture of aromatic hydrocarbons is a mixture of methyl ethyl benzene and tetrarnethyl benzene.

' 6. A process as defined by claim 1 wherein said mixture of aromatic hydrocarbons is a mixture of dimethyl ethyl benzene and tetramethyl benzene.

7. An improved refrigerant-lubricant composition for use in a compression refrigeration apparatus which comprises a major proportion of a fiuorochlorinated hydrocarbon refrigerant and from 1 to 10 weight percent of the hydrocarbon lubricating oil prepared by the process of claim 1.

References Cited UNITED STATES PATENTS 3,092,981 6/1963 Begeman et a1 252-68 3,169,928 2/1965 Herold 252-68 3,214,462 10/1965 Swenson et a1. 260-671 FOREIGN PATENTS 664,095 1/ 1952 Great Britain. 665,058 1/1952 Great Britain. 666,209 2/1952 Great Britain.

DELBERT E. GANTZ, Primary Examiner. C. R. DAVIS, Assistant Examiner.

U.S. C1. X.R. 252-68