US2474859A - Ethylene polysulfide polymer lubricant - Google Patents

Description

Patented July 5, 1949 UNITED s'rArEs PATENT ornce 2,474,859 ETHYLENE POLYSULFID 'LUBRIC Blyde A. Perkins, San Lore Rockwell Manula'cturin Pa., a corporation of Pennsylvania No Drawing. Application December Serial No. 637,256

I Comp ny,

E POLYMER ANT nzo, Calii'., assignor to Pittsburgh,

2 Claims. (01. zoo-cos) This invention relates to a new composition of matter and its preparation and is more particu-- service usually rapidly deteriorate under such conditions and necessitate frequent replacement.

The lubrication of valves used in modern chemical industries has created a demand for a lubricant which is particularly inert with respect to a wide range of solvents and corrosive fluids while maintaining requisite lubricating efllciency over a wide temperature range. The invention provides a lubricant which is substantially inert with respect to hydrofluoric acid and like strong corrosive fluids and substantially insoluble in hydrocarbons such as butane, isobutane, butene and other petroleum derivatives associated with the manufacture of high octane gasoline, and mixtures of hydrofluoric acid and these hydrocarbons, and it is a major object of the invention to provide such a novel lubricant and novel methods of making it.

It is a further object of the invention to provide a novel lubricant comprising the synthetic polymeric reaction product of a sodium polysulfide solution and ethylene dichloride after treatment of that product under special temperature conditions for a predetermined length of time to produce a lubricant of desired viscosity, and the process for making the lubricant.

A further object of the invention is to provide a novel process for making a lubricant of suitable viscosity for use in lubricated plug valves and which is chemically inert with respect to anhydrous hydrofluoric acid and petroleum hydrocarbons, wherein a special sodium polysulfide solution is reacted with ethylene dichloride to produce a synthetic ethylene polysulfide polymer, and the polymer mass is subjected tospecial heat treatment for a predetermined length of time to convert it to a form in which it is a lubricant having the above properties.

Further objects of the inventionwill appear as the description proceeds in connection with the appended claims.

In practice of the invention, I prepare a special 2 sodium polysulfide solution which is reacted with ethylene dichloride to produce a synthetic organic polymer, polymeric sodium polysulfide, and the polymer mass after purification such as washing is subjected to special heat treatment to alter the viscosity of the mass until it is satisfactory for use as a valve lubricant and like purposes. Two examples of processes for producing the invention will now be given, it being understood that these are given by way of illustration only and are not determinative of the scope of the invention, that scope being indicated and defined in the claims.

Example I 28.8 kilograms of sodium sulfide (sixty per cent concentrated technical) and 19.2 kilograms of sulfur are dissolved in 113.7 kilograms of water at F. to give a sodium-polysulflde solution having a sodium polysulfide ratio of N a2S3.5 to Na2S4,o.

I then slowly and gradually add 19.2 kilograms of ethylene dichloride to the heated sodium polysulfide solution at a rate which requires about forty minutes to add the ethylene dichloride, continuing agitation during this period, and then the reaction is allowed to proceed to completion, this taking about fifteen minutes more.

The resultant product of the above reaction is an ethylene sulfide polymer which is a fluid latex which is pumped into a suitable container where it is coagulat'ed and precipitated by addition of 17.7 kilograms of hydrochloric acid (20 B.) diluted five times in cold water. The acid solution is gradually and continuously added to the latex in small proportions until all the latex has been precipitated and the solution has reached a pH value between 3.5 and 4.0. The precipitate, which is an ethylene polysulfide polymer, is washed with cold running water to remove impurities.

To convert this ethylene polysulfide polymer into a form suitable for lubricant purposes, I

place the washed precipitate in an oil jacketedmixer where it is heated at about 400 F. for from one to two hours to drive ofi. volatile components 3 and obtain a product of desired viscosity for lubricant purposes.

Example II 28.8 kilograms of sodium sulfide (sixty per cent concentrated technical) and 19.2 kilograms of sulfur are dissolved in 118.7 kilograms of water at 160 F. to give a sodium polysulfide solution having a sodium polysulfide ratio of NazSas to NazSm as in Example I. This solution is placed directly in a steam and jacketed reactor and agitated and heated between 160 F. and 170 F., the emulsification of Example I being omitted.

I then slowly and gradually add 19.2 kilograms of ethylene dichloride into the reactor, at a rate requiring from two and one half to three hours to add all of the ethylene dichloride, maintaining the temperature between 160 F. and 170 F. and agitating the solution during this period. The resultant reacted material is a yellowish-green mass which is a rubbery and viscous ethylene polysulfide polymer. It is purified and washed with boiling water.

Thirty pounds of this viscous rubbery mass are placed in a suitable mixer heated by an oil jacket, and the mass is heated and agitated at about 380 F. to 400 F. for a period of about one and one half to two hours. Preferably this conversion temperature is 400 F. and maintained until the mass has a viscosity of the desired degree for lubricant purposes. This heat treatment drives off volatile components and converts the rubbery mas-s into an ethylene polysulfide lubricant of desired viscosity.

It will be noted that the essential difierence between Examples I and II is that in Example II, where the ethylene dichloride is added very slowly, ther is no intermediate latex form which must be precipitated as in Example I. Otherwise the essential considerations are similar.

It is essential to practice of the invention that the sodium polysulfide ratio in the solution be as specified in both examples, between Na2S:.5-and NazSao.

The conversion temperature limits for reducing the viscous polymer, the precipitate of Example I or the rubbery mass of Example II, to lubricant of the desired viscosity must also be strictly observed, as the conversion temperature must be between approximately 380 F. and 400 F. I have found that heating the polymer at 3'75 F. or lower for periods up to eight hours will not produce a lubricant of satisfactory viscosity. Similarly I have found that heating the polymer at 410 F. and higher will convert it into a hard mass not suitable for a lubricant.

The time of heating the polymer at 380 F. to 400 F. during conversion is also critical. I have found that heating the polymer at those temperatures for a period of three hours or more converts it into a hard rubbery mass unsuitable for lubricant use. The time of heating during conversion is a function of the desired viscosity, which property must be kept under observation during the operation. Preferably the conversion time for heating at 380 F. to 400 F. is about one and one half to two hours.

If desired, the lubricant end product may be blended with various materials such as anthracene oil to alter its viscosity to suit special conditions, much as extremely low climatic temperatures, without appreciable change in its chemical properties.

The above described synthetic ethylene polysulfide polymeric lubricant end product is completely inert with respect to petroleum hydrocarbons and anhydrous hydrofluoric acid, so that it is especially useful as a valve lubricant in lines in chemical processes handling such materials, and its physical properties, especially its viscosity as determined by its method of manufacture, are especially satisfactory for lubricated plug valve lubricants.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. The process of preparing a synthetic ethylene polysulfide polymer of desired viscosity for use as a plug valve lubricant comprising reacting an aqueous sodium polysulfide solution having a sodium polysulfide ratio of NazSas to Nazsio with ethylene dichloride to produce a polymeric ethylene polysulfide material and heating said material at in the range of 380 F. to 400 F. for between one and one half to two hours to convert it into a lubricant of said desired viscosity.

2. The lubricant prepared by the process defined in claim 1.

BLYDE A. PERKINS.

REFERENCES crrEn The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,923,392 Patrick Aug. 22, 1933 1,950,744 Patrick Mar. 13, 1934 2,192,700 Turner Mar. 5, 1940 2,221,650 Patrick Nov. 12, 1940 OTHER REFERENCES Martin, Ind. & Eng. Chem., Oct. 1936, vol. 28, Pages 11441149.