US2891010A - Waterproof silica-base greases - Google Patents

Description

United States Patent No Drawing. Application December 7, 1955 Serial No. 551,509

4 Claims. (Cl. 252 -28) This invention relates to the thickening of oleaginous liquids by means of finely divided, inorganic gelatinous material. It is especially directed to the preparation of water-resistant lubricants comprising an oleaginous vehicle thickened to a grease-like consistency with a nonsoa'p inorganic gelling agent for use in high temperature applications.

Although lubricating greases by ASTM definition are the shortage of conventional grease-making components. Greases employing inorganic gelling agents: can be prepared in the standard type of grease making equipment without requiring runusual processing conditions. Although the greases thickened with inorganic gelling agents are suitable for multi-service duty, their resistance to changes in consistency over a wide temperature range makesthem very desirable compositions for high temperature applications. While the consistency of soapthickened greases at elevated temperature is inimicably aifected, greases thickened with inorganic gelling agents retain their grease structure. If working of these greases has occurred, the base oil may distill or even ignite, but

no melting of the grease results. Unfortunately, these multi-purpose greases do not present an ideal solution to lubricating problems inasmuch as one serious deficiency in greases thickened with inorganic gelling agents is demonstrated by their lack of water resistance. This characteristic is fatal because exposure of a simple admixture of silica and oil to Water results in the rapid disintegration of the mixture into its component parts.

semi-solid. or solid combinations of a petroleum prod-f.

net and a soap or amixture of soaps, there have been developed a number of compositions which do not employ petroleum oils as the base constituent and a number of thickeners for these base liquids which are nonsoap gelling agents, but can be used in the preparation of? thickened compositions which functionally are the equivalents of a true; lubricating grease. Furthermore, thelubricating compositionsthus prepared have properties in" which soapcontaining petroleum base lubricating greases are generally deficient. In spite of the fact that the compositions of this invention do not conform with the "conventional definition of a grease, they will hereinafter be included in this category in order to facilitate the discussion of the instant invention.

Inorganic colloids capable of gel formation in oleaginous vehicles include alkali-ne earth metal oxides and hydroxides; carbonates of alkali metal and Iaikaline earth metals, ferric oxide, vanadium pentoxide, oxides and hydroxides of. polyvalentmetals, such as silicon, magnesium, aluminum, tin, chromium, etc.; sulfides of polyvalent metals qincluding cuprous sulfide, ferrous sulfide, and others. The preparationof inorganic colloidal thickenirrgagents is comprehensivelydiscussed in. the patent literature: For examples, see US. Patents 2,260,645, 2,583,603-4, 2,554,222, 2,594,822, 2,629,691., and others. Also included are the siliceous gelling agents prepared by pyrolyzing silicon compounds, such as silicon tetrachloride, tetraethyl silicate, or a chlorosilane to produce finely divided materials. Examples of this type of gelling agent are. theCab-O-Sils marketed by the Godfrey L. Cabot, Inc. M

Anon-soap gelling agent which has found considerable application in the preparation of lubricating greases is finelydivided silica. Accordingly, the following discussion is directed. to a description of greases prepared by the use ofthis material. However, this is only illustrative and non-limiting. This material, when dispersed in a suitable liquid medium including petroleum oil lubricating fractions, will produce a gelatinous composition with a greaseelikestructure having lubricating properties. i 'The "development of inorganidgell ing agents apparently origipated in Germany during World War II as a solution. to

It has been found, however, that by treating the gelling agents employed in the preparation of lubricating greases with suitable reagents, the inorganic gel-oil composition can be stabilized against the detrimental eifect of 'Water. Improvement in the water resistance is effected by coat ing the inorganic gelling agent or by using suitable additives in the lubricating :grease. Boner, in Manufacturing and Application of Lubricating Greases, Reinhold,..1954, at page704 et seq., comprehensively discusses the modification of silica gel to increase water resistance based on a compilation of the prior art.

Various methods are employed to evaluate the resistance to breakdown of the grease structure in the presence of water. One technique involves the addition of incremental amounts. of water with subsequent mixing of the water-lubricant system, and observation of the accompanying change in grease structure, if any. Another test immerses a sample of the grease, retained in a suitable specimen holder, into boiling water for onehalf hour. Apparently a more rigorous procedure for determining the water resistance of a grease of this nature is the test method ASTM designation: D1264-53T, described in the 1953 Supplement to Book of ASTM Standards, Part 5, ASTM. In this method the grease sample is retained in a rotating ball bearing and subjected to the washing action of distilled water for 1 hour at specifled test temperatures. It has been foundthat waterproofing agents generally considered adequate for imparting water resistance to water-susceptible greases prepared from inorganic Igelli-ng agents are unsatisfactory for making a grease compoistion'which will give satis factory results, when subjected to the scrutiny of the aforementioned ASTM method for determining the water washout characteristics of a lubricating grease.

It is therefore an object of this invention to provide a non-soap thickened lubricating grease having enhanced 'water resistance. Another object of this invention is the production of a lubricating grease having improved resistance. to water washout. It is also an object of this invention to improve the water washout characteristics of aIsilica-thickened lubricating grease. These and other objects will become apparent from the following detailed description of this invention. r t p According. to this invention, it has been found that order to provide a non-soap-thickened lubricating grease having excellent resistance to water washout, it is necessary to incorporate in the grease composition a combination waterproofing additive comprising an admixture of (1) an oil-soluble alkylaryl polyether alcohol prepared by condensing an alkyl phenol and ethylene oxide, and (2) an oil-soluble aliphatic monoether or polyoxyalkylene glycol prepared by the addition of a monohydroxy aliphatic alcohol to 1,2-propylene oxide.

In formulating the grease composition 4 ration of suitable compositions are reported in U.S. Patent 2,448,664. Although a variety of monohydric aliphatic alcohols can be employed in the reaction, preferred compositions are prepared by reacting butanol and 1,2-propylene oxide. By varying the molecular weight of the addition product, changes in product characteristics are obtained, as shown in Table I, wherein are tabularly summarized the properties of proprietary compositions of this nature marketed by Carbide and Chemicals of this inven- Corporation under the mark Ucon.

TABLE I Properties of Ucon brand lubncants-LB series LB140 LIB-300 LB-400 LB-550 LIB-650 Viscosity, SUS at: i

Viscosity, centistokes at:

50 F 58, 000 300, 000 510, 000 850, 000 VI. (ASTM D 147 142 142 140 140 Your Point (AS 50 -40 -85 ---30 25v Density at 210 F g per cc 0. 921 0.933 0. 936 0.939 0.940 Density at 100 F., g. per cc 0. 966 0. 979 0.983 0. 985 0. 980 Specific Gravity at 60 F..- 0.983 0. 997 1. 001 1. 003 1.004 Gravity, deg. API at 60 F 12. 5 10. 5 9. 7 9. 5 9.4 Flash Point (AS'IM D-92-33), F 440 470 485 510 625- Fire Point (ASTM D-92-33), F 510 57 580 580 680 Carbon Residue (ASTM D-189-41), percent... 3 p

- Ash (ASTM D-482-43-T), percent 1 Less than 0.01.

tion, a suitable inorganic gelling agent such as those described above, preferably silica aerogel, which has been prepared according to the method of Kistler in U.S. Patent 2,260,625, is incorporated in a selected oleaginous vehicle including conventional mineral lubricating oils of Pennsylvania, Mid-Continent, Gulf Coast, East Texas, California, etc. origin. Other oleaginous bases may also be employed, such as synthetic lubricating oil derived from the polymerization of olefinic charge stocks; aliphatic and aromatic esters, viz., aliphatic esters of dicarboxylic acids, e.g., dioctyl sebacate; organic phosphates, e.g., tricresyl phosphate; silicone oils, and other oleaginous liquid possessing satisfactory lubricity characteristics. To impart to the finished grease satisfactory water washout resistance, the waterproofing additive of this invention is admixed with the oil-thickener blend. This oil-soluble additive consists of a combination of (1) an alkyl aryl polyether alcohoLand (2) an aliphatic monoether of a polyoxyalkylene glycol. I

The polyether alcohol constituent of the water-proof- 'ing additive is prepared by condensing an alkyl phenol wfih ethylene oxide to form an oil-soluble producthaving a molecular weight of about 200-650. Phenols having C C alkyl substituents, such as di-isobutyl phenol, octyl phenol,;nony1 phenol, octadecyl phenol, tridecyl phenol, dioctyl phenol, and others, or mixtures thereof, can be condensed according to conventional techniques with ethylene oxide to provide polyether alcohols of molecular weight suificient to impart oil solubility characteristics to the polyether alcohol. An example of a preferred alkyl aryl polyether alcohol is Triton X-45, a

' proprietary compound marketed by Rohm and HaasCom- The other constituent of the waterproofing additiveis an oil-soluble aliphatic monoether of a polyoxyalkyl'ene glycol which is synthesized by adding a monohy'drox'y aliphatic alcohol to propylene oxide. Details for prepa- For the compositions of this invention, it is preferred that the aliphatic monohydric alcohol-propylene oxide addition product having an average molecular weight of about 800-1600 (acetyl value) be employed. According to this invention, the combination of (1) an oil-soluble additive product of an aliphatic monohydric alcohol and propylene oxide, and (2) an oil-soluble alkyl aryl polyether alcohol, in the ratio of 1 to 15 parts by weight of the former to one part by weight of the latter, will improve the water washout characteristics of a non-soap thickened grease. It is preferred that a ratio of 4,-8:1 be employed to give optimum results. The amount of composite additive employed will depend upon the amount of gelling agent used. Generally, 9 to 10% by weight, based on gelling agent, will provide satisfactory results. However, amounts outside this range may be employed. In order to prepare a finished grease it may be necessary to add other functional additives to impart to the finished grease corrosion and oxidation resistance, extreme pressure characteristics, etc. Table II shows illustrative ranges of ingredients. I

TABLE II Parts by Weight Component Suggested Preferred Liquid, oleaginous lubricating vehicle -96 88-94 Non-soap gelling agent 4-20 6-12. Water-proofing additiv 3- 0 .5-1.1. Functional additive, e.g., rust inhibitor,

anti-oxidant, V.I. improver, E.P. agent. As required. As required.

I The subject invention is illustrated in a non-limited manner by the tabular summary of data shovvnfin Tab1e.III....: x

anemic TABLE III Composition, Wt., A B O D E F G H I J K L M N .Perceiit Silica Aerqgel IIhickener 9. 9. 0 9. 0 19:0 --9. 0 9. 0 9. 0 9. 0 9. 0 9. 0 9. 0 9. 0 9. 0 9.0 W erprooflngAgent: 1 -Aliphatio monoether .oi polyoxyalkylene gly- (:01 0. 72 0.74 0. 65 0. 80 0. 56 0. 92 0. 64;. ,0. 80 Alkyl aryl polyether al- 1 i i .1 001101 3 0. 09 0. 074 0.16 0.05 0.18 1039. 0.108; 0.10 o: Aliphatic monoether of polyoxyalkylene glyl i col lalkyl aryl polyether 81001101 8 4 16 3.1 1,3- o -l--. :8= 8 Waterproofing AgentX p p h 100 Silica Aerogel..- 9 9 9 9. 4 8. 2 10 7 5 5 7 "7 '10 "8' 10 ineral Lubricating Oil L.-- 90. 19 90.19 90.19 90.16 90. 26 90. 08 90.37 90. 55 90. 55 90. 37 90. 37 90.1 90. 28 90. 10 rease Characteristics:

Penetration Unworked 2 49 235 237 233 239 241 250 255 238 249 248 249 239 238 W0rked- 282 262 259 271 257 276 276 309 275 264 313 282 276 265 Water Washout wt. i

percent grease loss n.-- 21 15 39 26 39 22 41 56 59 25. 2 84.1 60. 4 24. 3

l santoc'el ARD, a proprietary silica arog'el marketed by Monsanto Chemical Company, having a particle size of 3-5 microns in diameter, a bulk density of 0056-0064 gmsJml. I

i UOON-LB 550, a proprietary composition marketed by Carbide and Carbon Chemicals comprising an oil-soluble addition product of butanol and 1,2-propylene oxide having an average molecular weight of about 1 4 3 Triton X45 a proprietary compound marketed by Rohm and alcohols having an average molecular weight of 338-514 and prepared by 00 (acetyl value) and having the characteristics shown in Table I. aas Company, comprising an oil-soluble admixture of homologous polyethcr condensing di-isobutyl phenol and ethylene oxide.

Intermediate V.I. bright stock mineral lubricating oil prepared by phenol extracting, MEK dewaxing, and clay contacting a Mid-Continent lubricating oil fraction, and having the following characteristics:

Viscosity, sUs at 210 16.4 Gravity, API 24. 5 Flash, F. (00C) 565 Fire, F. (O0C) 630 Viscosity Index 91 Pour point, F., ASTM 0 Color NPA (ASTML..- 7 Carbon residue, percent 1. Sulfur, percent 0. 80 Neut. No. (1) l 0.05 Ash, perr n 0.002

' ASTM Designation D 128-47. ASTM Designation D 1264-531.

The eifcctiveness of the instant invention for enhancing the water washout characteristics of a non-soap-thickened lubricating grease is further illustrated by comparison with a lithium soap-thickened lubricating grease having the following composition:

Component Percent Lithium 12-hydroxy stearate Mineral oil base:

Intermediate V.I. (160 S.U.S. at 210 F./90 V.I.) Mid- Continent solvent-refined, bright stock lubricating oil. High VI. (85 8.115. at 100 F./95 V.I.) Mid-Continent,

solvent-refined, neutral lubricating oil Phenol extract of a bright stock lubricating oil fraction 1 A mineral oil lubricating fraction obtained as an extract from the phenol extraction of a dewaxed and deasphalted Mid-Continent residuum and having the following characteristics:

It will be seen that, by means of this invention, a non-soap-thickened lubricating grease can be made, which will have water washout characteristics comparable to a lithium soap-thickened lubricating grease, a composition to which is generally attributed good water resistance, and is used as a multi-purpose lubricant. To further illustrate the advantages of the instant invention, a non-soap-thickened lubricating grease was prepared without employing the composite water-proofing.

agent of this invention. It was found that this grease had no resistance to water washout and completely disintegrated under the water washout test conditions.

I claim as my invention:

1. A silica-thickened grease having enhanced water washout characteristics consisting essentially of a lubricating oil having incorporated therein a finely divided silica gelling agent in an amount sufficient to impart a grease-like consistency to said lubricating oil, and a composite water-proofing agent consisting essentially of 4- 10 parts by weight of (1) an oil-soluble mono-alkyl ether of a polyoxyalkylene glycol produced by reaction of a monohydric aliphatic alcohol and 1,2-propylene oxide having a molecular weight of 800-1600 (acctyl value), and one part by weight of (2) an oil-soluble mono-alkylaryl ether of a polyoxyethylene glycol produced by reaction of a (l -C alkyl-substituted phenol and ethylene oxide having an average molecular Weight of 200-550, said waterproofing agent being present to the extent of 9-10% by weight of the silica in an amount suflicient to improve substantially the water-washout characteristics of said grease.

2. A grease composition in accordance with claim 1 in which the composite waterproofing agent contains 4-8 parts by weight of compound (1) and one part by weight of compound (2), said Waterproofing agent representing about 9% by weight of the silica.

3. A silica-thickened lubricating grease composition consisting essentially of:

Components Parts by Weight 7 4. silica-thickened lubricating grease compositien References Cited in the file of this patent essnflallyofi UNITED STATESPATENTVS v. l G t 1 H f b Z 2,573,650 Peterson Oct. 30,1951 V 33gb; 2,652,365 Moore et a1. 'Sept'. '15, 1953 1 12,680,095 Hotten etal. 4:1 pm 1;; 1954 Mgne raglub rmatj g'nn 3' 2,739,121 Weihe *et a1. 1 v Iay 20, 1956 g s g gggggf gg 9 Marshall et al. 'OCLw9p 1956 a. An oil-soluble mono-alkyl ether oia olyoxyalkylene if I 3 V I glycol produced by reaction of a mono ydric aliphatic alcohol and 1;2-propylene oxide having amoleeular weight of 800-1,600 (acetyl value) 0.80 b. An oil-soluble mono-alkyl aryl ester of polyoxyethylene glycol produced by reaction of a. 01-0 aJkyl-substituted phenol and ethylene oxide having an average molecular weight of200-550 0.10

Claims (1)

1. A SILICA-THICKENED GREASE HAVING ENHANCED WATER WASHOUT CHARACTERISTICS CONSISTING ESSENTIALLY OF A LUBRICATING OIL HAVING INCORPORTED THEREIN A FINELY DIVIDED SILICA GELLING AGENT IN AN AMOUNT SUFFICIENT TO IMPART A GREASE-LIKE CONSISTENCY TO SAID LUBRICATING OIL, AND A COMPOSITE WATER-PROOFING AGENT CONSISTING ESSENTIALLY OF 410 PARTS BY WEIGHT OF (1) AND OIL-SOLUBLE MONO-ALKYL ETHER OF A POLYOXYALKYLENE GLYCOL PRODUCED BY REACTION OF A MONOHYDRIC ALIPHATIC ALCOHOL AND 1,2-PROPYLENE OXIDE HAVING A MOLECULAR WEIGHT OF 800-1600 (ACETYL VALUE), AND ONE PART BY WEIGHT OF (2) AND OIL-SOLUBLE MONO-ALKYLARYL ETHER OF A POLYOXYETHYLENE GLYCOL PRODUCED BY REACTION OF A C1-C18 ALKYL-SUBSTITUTED PHENOL AND ETHYLENE OXIDE HAVING A AVERAGE MOLECULAR WEIGHT OF 200-550, SAID WATERPROOFING AGENT BEING PRESENT TO THE EXTENT OF 9-10% BY WEIGHT OF THE SILICA IN AN AMOUNT SUFFICIENT TO IMPROVE SUBSTANTIALLY THE WATER-WASHOUT CHARACTERISTICS OF SAID GREASE.