US3396111A - Lubricants comprising certain diesters of maleic, fumaric or itaconic acids and method of lubricating - Google Patents

Description

United States Patent 3,396,111 LUBRICANTS COMPRISING CERTAIN DIESTERS 0F MALEIC, FUMARIC 0R ITACONIC ACIDS AND METHOD OF LUBRICATING Robert K. Smith, Springfield Township, Delaware County, and Sidney J. Barber, Philadelphia, Pa., assignors to E. F. Houghton & Co., Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Continuation-impart of application Ser. No. 323,909, Nov. 15, 1963. This application May 6, 1965, Ser. No. 453,807

29 Claims. (Cl. 25256) The present invention relates to improvements in lubrication of metals heretofore difiioult to lubricate and, more particularly, to lubricating compositions and methods for lubrication of those metals highly susceptible to the formation of oxides which erode or gall the metal bearing surfaces. This application is a continuation-inpart of application Ser. No. 323,909, filed Nov. 15, 1963, now abandoned.

Historically, viscous fluids have been used as lubricants in order to establish a hydrodynamic film which substantially completely separates moving metal parts. Under conditions of extreme pressure, oscillating motion or relatively low rates of movement between metal parts, the hydrodynamic film may be destroyed. Metal to metal contact then occurs with incipient welding between the rougher portions of the metal surfaces. Even though moderate surface pressures per unit area exist, these pressures are magnified manyfold in rougher surface areas so that point to point pressures therein of many thousands of pounds are created. Under these intense pressures, welding and subsequent gouging or erosion of the metals 0cour. This phenomenon results in rapid wear of moving parts and leads to early failure of the mechanism.

Lubricating compositions to overcome such conditions have been prepared containing chemically active elements, such as chlorine or sulfur, which are capable of chemical reaction with certain metal surfaces, such as ferrous metal surfaces.

It is generally believed that such elements form chlorides or sulfides on the metal of the surface to be lubricated. Such salts then act as physical barriers to prevent metal to metal contact, thereby eliminating or minimizing welding. In addition, these salts have the important property of being softer than the surface of the parent metal to be lubricated. Gouging or galling of such metal surface by these compounds, therefore, is not a problem.

Metals such as magnesium and aluminum have not been used successfully as hearing materials for a number of reasons. They are difficult to machine or form with polished surfaces because of such characteristics as drag or scratching. The former is essentially the result of localized welding between the cutting or forming tool and the metal workpiece. The latter, which necessitates a finishing step to restore the desired surface finish, arises from impressment of hard oxides of the metal into the metal surface. Lubrication of aluminum with conventional extreme pressure agents containing chlorine or sulfur has been unsuccessful since any chlorides or sulfides of aluminum which are formed are rapidly converted to abrasive aluminum oxide.

A principal object of this invention is to provide a novel method of lubricating stainless steel, the structural metals and alloys of the structural metals of Groups II, III and IV of the Periodic Table, particularly aluminum and its alloys.

Another principal object of this invention is to provide novel lubricating compositions particularly useful in lubricating stainless steel, the structural metals and alloys of the structural metals of Groups II, HI and IV of the Periodic Table, particularly aluminum and its alloys.

ICC

A further object of this invention is to provide novel improved lubricating compositions comprising an oleaginous base and a dialkyl ester of certain alpha,beta unsaturated dibasic acids.

Another object of this invention is to provide for the lubrication of metals heretofore difficult to lubricate, such as aluminum, by means of dialkyl esters of certain alpha, beta unsaturated dibasic acids.

These and other objects will become evident from a consideration of the following specification and claims.

According to this invention there is provided a novel and improved method of lubricating two solid surfaces between which there is relative movement, at least one of which surfaces is selected from the group consisting of stainless steel, the structural metals and the alloys of the structural metals of Groups II, III and IV of the Periodic Table, which comprises maintaining between such surfaces a compound of the formula RO-()-X H OR wherein X is a divalent radical selected from the group consisting of CH=CH-- and R is a constituent selected from the group consisting of alkyl, methyl alkyl and ethyl alkyl where the alkyl chain contains from 6 to 20 carbon atoms, and R is aconstituent selected from the group consisting of alkyl, methyl alkyl and ethyl alkyl where the alkyl chain contains from 12 to 20 carbon atoms.

The novel lubricating compositions of this invention comprise an oleaginous base and a compound of Formula 1. Preferred compounds for use according to the present invention comprise dilauryl maleate and distearyl maleate.

According to this invention it was found that aluminum and its alloys, as well as the structural metals and alloys of the structural metals of Groups II, III and IV of the Periodic Table, and the stainless steels, which metals and alloys cannot be satisfactorily lubricated with ordinary extreme pressure lubricants which contain chlorine and/ or sulfur, may be satisfactorily lubricated by means of a compound of Formula I either alone or in combination with an oleaginous base. In either case, extremely low coefiicients of friction are provided.

By the term structural metals of Groups H, III and IV of the Periodic Table as used in this specification and claims is meant those metals whose physical properties, such as hardness, modulus of elasticity, elastic limit, etc., are such as to make them satisfactory for use as bearing surfaces when properly lubricated. By the term alloys of the structural metals of the aforesaid groups of the Periodic Table is meant compositions containing 50 percent or more, by weight, of the structural metal. By the term stainless steel is meant those well known steels which are commonly referred to as stainless, typical of which are the high chromium steels.

Typical of the structural metals of Group II are beryllium, magnesium, zinc and cadmium. Those of Groups III are boron, aluminum, scandium, gallium, yttrium and indium, and those of Group IV are titanium, germanium, zirconium and tin.

This invention is particularly useful in lubricating hearing surfaces composed of aluminum and its alloys.

Referring to Formula I, above, it can be seen that the compounds empolyed in the present invention are diesters of alpha, beta unsaturated dibasic acids. The compounds are diesters of maleic and fumaric acid when X is CH=CH and diesters of itaconic acid when X is Preferred compounds are the diesters of maleic acid.

Where R and R are the same, typical diesters for use in this invention are dilauryl maleate, distearyl maleate, dilauryl fumarate, distearyl fumarate, dioctyl itaconate, and dipalmityl itaconate. Typical mixed diesters where R and R are different are lauryl stearyl maleate, tridecyl stearyl maleate, 2-ethylhexyl stearyl maleate, 2- octyl stearyl maleate, l-nonyl stearyl fumarate, l-nonyl lauryl fumarate, lauryl stearyl itaconate and 2-octyl stearyl itaconate. Where R and R are different the average composition of the diester product may vary from a small fraction of R or R, e.g., 0.1 mol of R or R per mol of acid to a very large portion, as for example 1.9 mols of R or R. Typical examples of products containing various proportions of R and R are (stearyl) (lauryl) maleate (stearyl) (lauryl) fumarate (stearly) (lauryl) itaconate Inasmuch as many of the esters which satisfy the above Formula I are solid at ambient temperatures, the use of a solvent or oleaginous base to satisfactorily introduce the ester to the system for lubrication purposes may be desirable.

The diesters which are useful for the purposes of this invention may be prepared in well known manner by reacting maleic or fumaric acid or their corresponding anhydrides, or itaconic acid with one or a mixture of monohydric aliphatic alcohols. The reaction is one of esterification with water being produced as a by-product. In preparing those diesters where R and R are the same, 2 mols of aliphatic alcohol are used per mol of acid or anhydride. Where mixed diesters are desired, a total of 2 mols of aliphatic alcohols per mol of acid or acid anhydride are used, the proportions of the various alcohol reactants depending upon the proporations desired for the mixed diester products, as described hereinabove.

The esterification reaction proceeds at elevated temperature of the order of 120 to 160 C. and the reaction is generally complete in about 3 to 6 hours. Water which is a by-product of the reaction preferably is continuously removed to drive the reaction to completion.

The lubricating compositions of this invention comprise an oleaginous base and one or more of the compounds of Formula I above. Generally, such lubricating compositions will contain at least about percent, by weight of the total composition, of such a diester or mixtures of diesters, and preferably from about 10 to about 50 percent. For many purposes the above described diesters may be used alone as lubricating materials. The use of mixtures of two or more of such diesters may prove advantageous for the purpose of providing desired viscosities, melting points or volatility characteristics.

The oleaginous base used in the compositions may be selected from a wide variety of natural or synthetic lubricants. Thus for example, natural oils can advantageously be employed. Illustrative of such natural oleaginous bases are mineral oils such as naphthlene and paraflin base oils, vegetable oils such as cotton seed oil and castor oil; animal and marine oils such as sperm whale oil, lard oil, blown fish oil and degras; and mixtures thereof. Of the natural oil bases, mineral oils are preferred. A typical mineral oil base for extreme pressure lubrication will be characterized by a viscosity of 35-350; Saybolt Universal seconds at 210 F., a viscosity index in the range of from 25 to 150, and a flash point of between about 275 and 600 F.

Polyorganosiloxanes, also known as silicones, or silicone polymers, comprise one class of synthetic lubricant bases of commercial importance which may be improved in properties to a substantial degree by modification in accordance with this invention. Polysiloxanes are compounds comprising essentially silicon atoms connected to one another by oxygen atoms; In liquid polyorganosiloxanes, or silicones, of the lubricating oil viscosity range, a preponderant number of the remaining valences of the silicon atoms are satisfied by the substitution thereon of organic radicals, attached by a carbon-to-silicon bond. Examples of such organic radicals are aliphatic radicals including alkyl radicals such as methyl, ethyl, propyl, butyl, and so forth; alicyclic radicals such as phenyl, cyclohexyl, diphenyl, anthracyl, naphthyl, and so forth; aralkyl radicals such as benzyl and alkaryl radicals such as tolyl, xylyl, and so forth; and the like. Relatively common oils of this type are dimethylsilicone polymer, phenylmethylsilicone polymer, chlorophenylmethylsilicone polymer, and so forth. Of particular utility for lubricating purposes are silicones in which the silicon atoms are sub stituted by two different organic radicals, e.g. methyl and phenyl radicals. Especially elfective properties have been obtained when the organic radicals substituted on the silicon atoms in the silicone polymers are in turn substituted by halogen atoms, especially chlorine atoms. Thus for example, the silicone may be substituted by chlorophenyl radicals such as dichlorophenyl, trichlorophenyl and tetrachlorophenyl radicals, other valences of the silicon atoms being satisfied by the hydrocarbon radicals such as methyl radicals or the like. As is well known in the art, the silicones intended for use as oleaginous bases will desirably contain an average of from 1.9 to 2.67 organic groups per silicon atom. Remaining valences, if any, of the silicon atoms may be satisfied by radicals attached to the silicon atoms in the compounds from which the silicone polymers are prepared, such as hydrolyzable organo-substituted silanes; or by the product of hydrolysis of such radicals, such as hydroxide radicals.

Another class of synthetic oleaginous bases of particular interest in the practice of the present invention comprises organic polyesters. On the one hand, these may comprise esters of polycarboxylic acids, such as dicarboxylic acid diesters. Thus for example, such synthetic ester lubricants may have the general formula R(COOR (COORg) where R is an aliphatic or cycloaliphatic hydrocarbon radical of from 2 to 8 carbon atoms and R and R are the same or difierent and are branched chain alkyl or alkyl-substituted cycloalkyl radicals of at least 4 carbon atoms. Such esters may be derived from succinic, maleic, pyrotartaric, glutaric, adipic, pimelic, suberic, azelaic, sebacic, pinic, thiopropionic or oxypropionic acids or the like, specific esters of this nature including for example di(l methyl-4-ethyloctyl)glutarate, di(2-ethylhexyl)oxydibutyric acid, di(Z-ethylhexyDadipate, di(B-methylbutyl) azelate, di(Z-ethylhexyl) azelate, di (Z-ethylhexyl) sebacate, di(3,5,5 trimethylhexyl)sebacate, di(2-ethylhexyl)maleate, di(methylcyclohexyl)adipate, 2-ethylhexyl l-methylhexyl sebacate and the like. Alternatively, instead of derivation from a polycarboxylic acid, the polyester synthetic oleaginous bases may be produced by reacting a polyhydric alcohol with a monocarboxylic acid. Thus for example, a polyhydric alcohol such as ethylene glycol or pentaerythritol is esterified with an acid of relatively long chain length such as caproic, pelargonic, capric, lauric, myristic, palmitic or stearic acid, to produce a polyester of lubricating oil viscosity. Specific examples of such polyesters derived from polyols are pentaerythritol tetrapelargonate, pentaerythritol tetracaprate, pentaerythritol tetrapalmitate, pentaerythritol tetrastearate, ethylene glycol divalerate, diethylene glycol dicaprate, propylene glycol dicaprylate, and so forth. Another type of synthetic polyester lubricants which may be used as oleaginous bases in accordance with this invention will be complex esters obtained by esterifying a polycarboxylic acid with a diol, together with a monohydric alcohol and/ or a monocarboxylic acid. Thus, complex esters which may be employed as oleaginous bases may be obtained by esterifying one mole of a dicarboxylic acid with 2 moles of a glycol and 2 moles of a monocarboxylic acid; or by esterifying one mole of a dicarboxylic acid with one mole each of a glycol, a monocarboxylic acid and a monohydric alcohol. Specific examples of a suitable complex ester are the ester prepared from one mole of ethylene glycol, two moles of sebacic acid and two moles of 2-ethylhexanol; and the ester prepared from one mole of triethylene glycol, one mole of adipic acid, one mole of n-caproic acid and one mole of Z-ethylhexanol.

In addition to the above-mentioned classes of synthetic lubricating base stocks comprising types of present major commercial importance, there are a number of other oleaginous bases which can be used if desired in the practice of this invention. Thus for example, such lubricant bases may comprise hydrocarbon oils prepared by polymerization of unsaturated hydrocarbons. Polyethers of the nature of high molecular weight polyoxyalkylene compounds, derived for example from ethylene oxide, propylene oxide and the like substances, form another useful class of lubricant bases, and similarly, there may be employed oleaginous bases of related srtucture, such as propylene oxide-tetrahydrofuran copolymers, and polyaryl ethers. Besides the silicones discussed above, additional silicon derivatives of interest in this connection comprise silanes, silphenylenes, organosilicates and disiloxanes such as hexaalkoxydisiloxanes of lubricating oil viscosity.

Other synthetic oleaginous bases which may be mentioned include fluorocarbon oils such as perfluorinated petroleum oils; tetra-substituted ureas; and esters such as dimethylcyclohexyl phthalate, trioctyl phosphate; and similar fluids adap ed for lubricant applications.

Mixtures of oleaginous bases may sometimes be preferred to any single lubricant fluid, and are included in the scope of this invention.

The compositions of this invention may also comprise other property-modifying components which supplement or complement the effect of the present salts, such as antioxidants, structure stabilizers or viscosity improvers, extreme pressure additives, thickeners or the like.

Lubricating compositions including compositions as provided by this invention may also advantageously comprise stabilizers, antioxidants and the like. As antioxidants, there may be used for example an alkylphenol such as 2,4,6- trimethylphenol, pentamethylphenol, 2,4,6-tri-tert-butylphenol and the like, and aminophenol such as benzylaminophenol, an amine such as dibutylphenylenediamine, diphenylamine, phenyl-a-naphthylamine, phenathiazone, dinaphthylamine and so forth, or a metal salt such as iron octoate and so forth, Stabilizers which tend to preserve the desired properties of the greases may also be included in the compositions. Such stabilizers may comprise, for example, a-aminoanthraquinone, benzanthracene, fluoroanthene, a-naphthylamine, N,N-dinaphthylphenylenediamine, benzoguanamine, die-tert-butylhydroquinone, quinazarine and Indanthrene blue, as well as inorganic mate rials such as mica, graphite, glass fibers and silica.

It may sometimes be advantageous to introduce thickeners of types known in the art hitherto into lubricating compositions comprising the products of this invention, as for example, where such products are employed as extreme pressure additives. Thickeners which may be used in such case may comprise, for example, a soap such as the lithium salt of hydroxystearic acid; silica material such as an aerogel; a ureide, urethane or the like such as a ureide prepared by reacting a diisocyanate such as tolylene diisocyanate with an amine such as aniline, p-chloraniline, or a mixture of the two; and so forth.

The invention is illustrated but not limited by the following examples.

In the following examples, the coeflicient of friction was determined by the manner described and illustrated in French Patent No. 1,322,451. The cup or rider was made of steel and the washer of 2 S aluminum. The rider, which had a flat annular surface of 0.393 square inch was rotated at 0.88 rpm. to give a surface speed of 0.0461 inch per second against the test washer under a load of 10 kg. Both the rider and washer were immersed in a cup containing the test lubricant. The tests were run at room temperature for twenty minutes.

Example I 25 g. (0.25 mol) of maleic anhydride and g. (0.5 mol) of stearyl alcohol were dissolved in 350 ml. of xylene along with 0.1 g. of p-toluene sulfonic acid in a one liter flask equipped with a stirrer, thermometer, and reflux condenser having a water trap. This solution was heated to reflux for 4 hours at the end of which time a total of 5 g. of water was collected. At this stage of the reaction, the acidity was found to be 0.3% calculated as stearic acid. The xylene was stripped at C. and at a pressure of 20 mm. of mercury, a yield of 147 g. (95.5% of theoretical) of distearyl maleate was obtained.

The distearyl maleate was stirred with an oil of 100 SUS to form a lubricating composition containing 10 percent by weight of maleate ester. This composition was tested for coefficient of friction and wear characteristics under boundary lubrication conditions in the manner described hereinabove. The coefllcient of friction between the steel cup and the aluminum washer was determined to be 0.04, as compared with that of more than 0.5 for the 100 SUS oil alone. The lubricating composition containing 10 percent distearyl ester merely permitted polishing of the aluminum washer wear surface in contrast to gouging and galling caused by the 100 SUS oil.

Example II 2300 g. of xylene were place in a five liter pot equipped with agitator, reflux condenser and dropping funnel 220 g. of maleic anhydride and 815 g. of lauryl alcohol were added to the xylene and stirred until the material was adequately mixed. 5 g. of p-toluene sulfonic acid were added and the reaction temperature increased to approximately 140 C. The solution was refluxed about 6 hours during which time a total of 44 g. of water were collected and discarded. The free fatty acid of the reaction mixture was found to be 0. The xylene was stripped from the reaction product by heating to 150 C. at a pressure of 20 mm. of mercury. After removal of the xylene, dilauryl maleate was obtained which had a viscosity of 25.53 centistokes at 100 F. and 3.80 centistokes at 210 F. The pour point of the product was 40 F. and the flash point was 310 F.

The lubricity of the dilauryl maleate was measured by evaluation in the friction machine described hereinabove. The coefficient of friction between the steel cup and the aluminum washer was found to be 0.12. The washer showed a very fine polish with slight wear track, but showed no evidence of grooving or galling.

Example III The same reaction system was used as in Example 11 employing 250 grams of xylene. 159 g. of maleic anhydride were placed in the flask along with 872 g. of stearyl alcohol. 8 g. of p-toluene sulfonic acid were added and the system was heated to reflux and held at that temperature for 6 hours. 30 g. of water were removed and discarded. After stripping the xylene following the procedure of Example II, the product was distearyl maleate which has a melting point of approximately 120 F. The coeflicient of friction between the steel cup and aluminum washer was found to be 0.11. The washer showed a well polished track with no evidence of appreciable wear.

Example IV 2-ethylhexyl stearyl maleate was prepared utilizing the same reaction system as was used in Example II. The coeflicient of friction between the steel cup and the aluminum washer was found to be 0.13. The washer showed a well polished track with no evidence of appreciable wear.

7 Example V Example VI A number of maleate diesters were prepared in the manner described in Example II. The composition of such esters and their lubricating properties are set forth in Table A below.

TABLE A Reactant Alcohol Coefficient Mols of Stearyl Mols of Lauryl of Friction Example VII A solution comprising 40% dilauryl maleate dissolved in a conventional bright stock having a viscosity of 300 seconds at 210 F. was prepared. Sufficient Vistac No. 1 was added to provide a final viscosity of 1560 seconds at 210 F. This composition was evaluated as a lubricant for the drawing of aluminum tubes. Extremely favorable reductions were obtained of the order of 40 to 45 percent in one pass through a conventional mandrel-die operation. The surface of the tube was polished showing no evidence of galling or chatter of the die on the tube.

While the invention has been described with reference to various particular embodiments thereof, it is to be appreciated that modifications and variations can be made within the scope of the invention.

What is claimed is:

1. The method of lubricating two solid surfaces between which there is relative motion, at least one of said surfaces being selected from the group consisting of stainless steel, the structural metals and alloys of the structural metals of Groups II, III and IV, which comprises maintaining between said surfaces a compound of the formula wherein X is a divalent radical selected from the group consisting of -CH=CH and CH2I3 CH9 R is a constituent selected from the group consisting of alkyl, methyl alkyl and ethyl alkyl where the alkyl chain contains from 6 to 20 carbon atoms, and R is a constituent selected from the group consisting of alkyl, methyl alkyl and ethyl alkyl where the alkyl chain contains from 12 to 20 carbon atoms.

2. The method according to claim 1 wherein at least one of said surfaces comprises aluminum.

3. The method according to claim 1 wherein at least one of said surfaces comprises an aluminum alloy.

4. The method according to claim 1 where X is CH=CH.

5. The method according to claim 1 wherein said compound comprises dilauryl maleate.

6. The method according to claim 1 wherein said compound comprises distearyl maleate.

7. The method according to claim 1, wherein said compound comprises 2-ethylhexyl stearyl maleate.

8. The method according to claim 1 wherein said compound comprises 2-octyl stearyl maleate.

9. The method according to claim 1 wherein X is 10. The method according to claim 1 wherein the compound comprises Z-ethylhexyl stearyl itaconate.

11. The method of lubricating two solid surfaces between which there is relative motion, at least one of said surfaces being selected from the group consisting of stainless steel and the structural metals and the alloys of the structural metals of Groups II, III and IV, which comprises maintaining between said surfaces a lubricating composition comprising a lubricating oil and a compound of the formula wherein X is a divalent radical selected from the group consisting of CH=CH and R is a constituent selected from the group consisting of alkyl, methyl alkyl and ethyl alkyl where the alkyl chain contains from 6 to 20 carbon atoms, and R is a constituent selected from the group consisting of alkyl, methyl alkyl and ethyl alkyl where the alkyl chain contains from 12 to 20 carbon atoms.

12. The method according to claim 11 wherein at least one of said surfaces comprises aluminum.

13. The method according to claim 11 wherein at least one of said surfaces comprises an aluminum alloy.

14. The method according to claim 11 wherein X is CH CH.

15. The method according to claim 11 wherein said compound comprises dilauryl maleate.

16. The method according to claim 11 wherein said compound comprises distearyl maleate.

17. The method according to claim 11 wherein said compound comprises Z-ethylhexyl stearyl maleate.

18. The method according to claim 11 wherein said compound contains 2-octyl stearyl maleate.

19. The method according to claim 11 wherein X is 20. The method according to claim 11 wherein said compound comprises Z-ethylhexyl stearyl itaconate.

21. A lubricating composition consisting essentially of a lubricating oil and as an additive, from about 5 to about 50% by weight of the total composition a compound of the formula i? it C wherein X is a divalent radical selected from the group consisting of -CH=CH and R is a constituent selected from the group consisting of alkyl, methyl alkyl and ethyl alkyl where the alkyl chain contains from 6 to 20 carbon atoms, and R is a constituent selected from the group consisting of alkyl, methyl alkyl and ethyl alkyl where the alkyl chain contains from 12 to 20 carbon atoms.

22. A lubricating composition according to claim 21 wherein X is CH=CH.

23. A lubricating composition according to claim 21 wherein said compound comprises dilauryl maleate.

24. A lubricating composition according to claim 21 wherein said compound comprises distearyl maleate.

25. A lubricating composition according to claim 21 wherein said compound comprises 2-ethylhexyl stearyl maleate.

26. A lubricating composition according to claim 21 wherein said compound comprises 2-octyl stearyl maleate.

27. A lubricating composition according to claim 21 whereinXis 28. A lubricating composition according to claim 21 wherein said compound comprises 2-ethylhexy1 stearyl itaconate.

29. A lubricating composition according to claim 21 wherein said compound comprises from about 10 to about 50 percent of said composition.

References Cited UNITED STATES PATENTS 1,993,737 3/1935 Graves et al 25256 X 5 2,134,736 11/1938 Renter 25256 2,460,035 1/1949 Rogers et a1. 25256 X FOREIGN PATENTS Great Britain. Canada. Great Britain.

OTHER REFERENCES Christensen: Lubricating Engineering, vol. 8 (1952),

pages 177-179.

DANIEL E. WYMAN, Primary Examiner.

W. H. CANNON, Assistant Examiner.

Claims (1)

1. 21. A LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A LUBRICATING OIL AND AS AN ADDITIVE, FROM ABOUT 5 TO ABOUT 50% BY WEIGHT OF THE TOTAL COMPOSITION A COMPOUND OF THE FORMULA