US2891981A - Bis (chlorophenyl)-tetramethyl-disiloxanes - Google Patents

Description

Patented June 23, 1959 BIS (CHLOROPHENYD-TETRAMETHYL- DISILOXANES Gordon C. Gainer, Turtle Creek, and Daniel W. Lewis,

Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvauia N Drawing. Original application March 24, 1950, Serial No. 151,821. Divided and this application September 30, 1955, Serial No. 537,888

3 Claims. (Cl. 260-4481) This invention relates to organosilicon compositions, organosiloxane fluids, hydraulic fluid apparatus embodying them, and bearing structures lubricated with such compositions.

This application is a division of our application S.N. 151,821, filed March 24, 1950, now abandoned.

Organosiloxane fluids comprising dimethyl silicones have been disclosed heretofore, and it has been suggested,

as in Ford and Wenzel Patent 2,456,496, that they be employed as lubricants because of their remarkably small change in viscosity with the change in temperature, as compared to other known lubricant materials. However, the dimethyl silicones have been found to be somewhat deficient in certain required lubricant properties. Thus, the dimethyl silicones have poor film strength particularly under boundary conditions and, in many bearing structures, excessive wear and a high coefficient of friction are encountered. Consequently, the dimethyl silicones are suitable for use only in a limited range of applications under light loads.

The coefiicient of friction of a commercially available dimethyl silicone lubricating fluid, representing about the best dimethyl silicone liquid available at the present time, is approximately 0.36. When tested in a Falex machine, the dimethyl silicone oils give an average wear rate, steel on steel, of 3600 wear units per hour. By contrast, highgrade petroleum machine lubricants have coeflicients of friction of from 0.13 to 0.20 under the same test conditions, while the average wear rate in the Falex machine is from 2 to 6, or slightly more, units per hour. It will be apparent, therefore, that in these properties at least the dimethyl silicones are not as satisfactory as the petroleum lubricants. In actual service, the dimethyl silicone lubricants are severely limited as to useful applications because of such deficiency in properties.

While it has been proposed to prepare certain solid halophenyl siloxanes, as for example in Patent 2,258,219, these previous proposals set forth solely the preparation of products that are solid resins, and no teaching therein relates to stable fluids. We have discovered, as will be set forth herein, a novel class of stable, fluid substituted phenyl siloxanes, wherein the substitutents on phenyl are certain electronegative radicals, and such siloxanes possess highly unexpected lubricating properties.

The object of this invention is-to provide novel organesiloxane fluids having a low coeflicient of friction and a low wear-rate.

Another object of the invention is to provide for novel organosilicon compositions having utility as lubricants.

Another object of the invention is to provide a process for preparing certain fluid organosiloxanes having substituted phenyl radicals attached to silicon.

A further object of. the invention is to provide organosiloxane lubricants that are comparable in lubricating properties with the best petroleum lubricants.

A still further object of the invention is to provide hydraulic mechanisms, such as. torque converters and servo-mechanisms, embodying organosiloxane liquids having a high degree of lubricity.

Other objects will in part be obvious, and will in part appear hereinafter.

In accordance with the present invention, there are prepared highly stable organosilicon compositions and organosiloxane fluids consisting of at least two silicon atoms per molecule connected to each other through oxygen atoms, the remaining valences of silicon being satisfied by monovalent methyl or methyl and phenyl radicals (the phenyl radicals not exceeding the number of methyl radicals) and substituted phenyl radicals, an average of not less than two substituted phenyl radicals being present in each molecule, the ratio of the substituted phenyl radicals to silicon atoms being not less than 0.02 and not exceeding 1.0, and the substituents on phenyl being selected from the group of monovalent electronegative radicals consisting of chlorine, fluorine, bromine, trifluoromethyl and halophenoxy radicals. The most astonishing results have been obtained by the inclusion of the substituted phenyl radicals in the organosiloxane molecule. The coeflicient of friction of the organosiloxane is markedly reduced, attaining values possessed by the best available petroleum lubricants. The wear rates, as determined by tests on the Falex machine, are phenomenally lower than those of dimethyl silicones and are found, in many cases, to be as low as or lower than the wear rates obtained with the best petroleum lubricants.

The electronegative radicals substituted for hydrogen in the phenyl radical may be present either singly in the ortho, meta or para positions or plurally. Two or more, up to five, of the electronegative radicals may be present on the same phenyl radical and such substitutents may be alike or different. Several diiferent substituted phenyl groups may be present in a single organosiloxaue molecule.

The substituted phenyl organosiloxane fluids may comprise either linear siloxane compounds, terminated by three monovalent organic radicals attached to the terminal silicon atoms at each end of the chain, or cyclic siloxane compounds. For some purposes, We prefer the linear siloxane compounds as lubricants, but a part or all of the siloxane molecules. present may be cyclic compounds.

In preparing the substituted phenyl siloxane compounds, We have found it convenient to start with a polysubstituted benzene compound, a di-substituted benzene compound being suitable, wherein at least one of the substituents is a halogen atom, preferably bromine or iodine, that will react with magnesium in ether to produce a Grignard reagent and the other substituents on the henzene ring are the particular electronegative radical substituents desired on the phenyl group in the siloxane. Examples of suitable benzene compounds are: o-, m-, and p-dibromobenzene, trichlorobromobenzene, difluoroiodobenzene, l-chloro-2-fluoro-4-bromobenzene, l-bromo- 4-trifluoromethylbenzene, 4-bromophenoxybenzene, tetrabromoiodobenzene, 1-iodo-3-chloro-4-trifluoromethylbenzene, and pentachloroiodobenzene. The Grignard reagent prepared from the polysubstituted benzene compound may be then reacted with a hydrolyzable silane, preferably one containing from two to three readily hydrolyzable groups, such as halide or hydrocarbonoxy radicals, the balance being methyl groups attached to silicon, in order to attach the substituted phenyl radicaltosilicon.

The resulting substituted phenyl silane will have theformula where X represents one or more monovalent electronegative substituents selected from the group consisting of chlorine, bromine, fluorine, trifluoromethyl and halophenoxy radicals, Y represents a readily hydrolyzable monovalent radical, and n is a whole number from 1 to 2. The silane may then be hydrolyzed and condensed to a liquid siloxane. The following equations are typical of the general reaction:

RC H -X Mg RC ILMgX (Grignard reagent) RCuHrMgX (H3)flsi01fl RC5H4S1(CH3)2 MgXCl aormsuonmol H O notmsuonozon 1101 where R represents an electronegative substituent on phenyl and X represents a halide, for example, bromine. It should be understood that the final product may be a polysiloxane with more than two silicon atoms. The replacement of all or part of the dimethyldichlorosilane in the above equations by monomethyltrichlorosilane will produce longer chain polysiloxanes.

It is not necessary to employ a Grignard reagent in preparing the compounds, since it is possible to halogenate, for instance, a phenyl silane compound to introduce one or more halogen atoms into the phenyl group. Thus, phenyl trichlorosilane may be chlorinated to produce chlorophenyl trichlorosilane which may be subsequently methylated to replace one or more of the chlorine atoms attached to silicon with methyl radicals:

where n represents a number from 1 to 5. Other reactions by means of which the electronegative substituents may be introduced into phenyl groups in a phenyl silane compound will be apparent.

Another convenient reaction for producing the silanes of the present invention is to add a mixture of polyhalogenosubstituted benzenes and a hydrolyzable organosilicon halide to magnesium in ether, and recover the halogenosubstituted phenylsilicon halide from the reaction product.

The hydrolyzable methylsilanes to be used in these reactions preferably contain from two to three hydrolyzable groups, for example, halogen, aroxy, acyloxy, or alkoxy groups, per molecule, the remainder consisting of methyl groups. Examples of such silanes are: dimethyldichlorosilane, dimethyldiethoxysilane, methyltribromosilane, dimethyldicyclohexoxysilane and methyltriethoxysilane.

The following examples illustrate the preparation of the compounds of the invention and their use:

EXAMPLE I Preparation of p-bromophenyldimethylchlorosilane A solution comprising 3.5 moles of p-dibromobenzene dissolved in three liters of anhydrous ethyl ether was added to 3.5 gm. atoms of magnesium with stirring and external cooling by means of an ice bath. The resulting Grignard reagent was added dropwise, with stirring to 5.25 moles of dimethyldichlorosilane. The mixture was stirred for several hours after the addition was completed and then permitted to stand until the solids settled as a sludge. The supernatant liquid was siphoned 0s. The sludge was filtered through a sintered glass filter and washed with dry ethyl ether. The filtrate was then added to the decanted liquid and the combined liquids were distilled to remove the ether and unreacted dimethyldichlorosilane. The high boiling liquid residue that remained was then fractionally distilled. A slight amount of white solid comprising p-dibromobenzene was recovered in the condenser. The main portion of the dis- 4 tillate boiling at a temperature of from 58 C. to 60 C. at 2 mm. of pressure was identified as p-bromophenyldirnethylchlorosilane.

EXAMPLE II Preparation of bis(p-brom0phenyl)tetramethyldisiloxane A hundred and fifty grams (0.6 mole) of the p-bromophenyldimethylchlorosilane of Example I was added dropwise with rapid stirring to cc. of 5% sulphuric acid. After completing the addition and stirring for an additional hour, the product was permitted to separate into two layers and the organic layer was withdrawn and added to 120 cc. of 75% sulphuric acid. After stirring for one hour, chopped ice and toluene were added with stirring. The toluene layer was permitted to separate and was decanted. The toluene solution so separated was washed several times with Water and dried thoroughly. The toluene was removed from the solution by distillation and the product was a fluid, composed of bis-(pbromophenyl)tetramethyldisiloxane, boiling at a temperature of C. to 151 C. at a pressure of 1.5 mm. Its properties were n 1.5501 and D 1.2176.

Analysis.Calcd. for C H BI Si O: C, 43.24; H, 4.50; Br, 36.03; Si, 12.61. Found: C, 34.30; H, 4.73; Br, 35.78; Si, 12.35.

The coefficient of friction, steel on steel, of the siloxance fluid was 0.14. The average wear-rate on a Falex machine, steel on steel, was 30 units per hour.

While sulfuric acid was used in this process, other mineral acids such as phosphoric acid, could have been employed.

EXAMPLE III Preparation of p-bromophenylmethyldiethoxysilane A small quantity of p-dibromobenzene was added to 0.9 gram atom of magnesium suspended in 200 cc. of anhydrous ethyl ether. When the Grignard reaction had commenced, a solution of 0.9 mole of p-dibromobenzene and 1.33 moles of methyltriethoxysilane in 1.5 liters of dry ethyl ether was added in a thin stream. When the reaction had been nearly completed, the entire mixture was heated externally and refluxed for three hours. The mixture was then subjected to distillation to remove the ethyl ether and unreacted methyltriethoxysilane and finally the reaction product was removed by vacuum and heating. Redistillation of the reaction product yielded substantially pure p-bromophenylmethyldiethoxysilane having a boiling point of 87 C. to 88 C. at two to three mm. Hg pressure, with index of refraction n 1.4980 and density D 1.219.

Analysis.Calcd. for C H BrSiO C, 45.68; H, 5.93; Br, 27.63; Si, 9.70. Found: C, 45.57; H, 5.91; Br, 27.74; Si, 9.56.

EXAMPLE IV Preparation of poly-p-bromophenylmethylsiloxane The p-bromophenylmethyldiethoxysiloxane prepared in Example III was hydrolyzed by mixing with 5% sulphuric acid and the partially condensed siloxane was then further treated with 75 sulphuric acid as in Example II. The resulting siloxane was removed in the toluene layer, washed with water and thoroughly dried, and the toluene was removed under vacuum. The resulting brornophenylmethyl silicone was a thick oil with a coeflicient of friction, steel on steel, of 0.13 and an average steel-on-steel wear rate in the Falex machine of 11 units per hour.

EXAMPLE V Preparation of p-chlorophenyldimethylethoxysilane and condensation product thereof A mixture of 2 moles of p-chlorobromobenzene and 3 moles of dimethyldiethoxysilane in anhydrous ethyl ether was added to 2 gm. atoms of magnesium turnings. The mixture was refluxed for twelve hours. After refluxing, the ether was distilled off and the unreacted dimethyldiethoxysilane was removed under reduced pressure. Finally the product, p-chlorophenyldimethylethoxysilane, was removed at a still lower pressure. Redistillation was employed to obtain pure p-chlorophenyldimethylethoxysilane having a boiling point of 61.5 C. at 1 mm. pressure and a refractive index n of 1.4950.

The purified p-chlorophenyldimethylethoxysilane was hydrolyzed and condensed in accordance with the procedure set forth in Example II to produce bis(p-chlor0- phenyl)tetramethyldisiloxane. This disiloxane polymer was a stable product with a HP. 153 C. at a pressure of 4 mm. n 1.5327, and D 1.1175. This fluid disiloxane when tested in a bearing exhibited a coefiicient of friction of 0.16 while its average steel-on-steel wearrate in a Falex machine was 7.7. Its viscosity at 100 F. was 4.3 centistokes and at 210 F., 1.6 centistokes.

EXAMPLE VI Preparation of p-chlorophenylmethyldichlorosilane and its condensation products A mixture of 2 moles of p-chlorobromobenzene and 3 moles of methyltrichlorosilane in 1.5 liters of dry ethyl ether was added to 2 gm. atoms of magnesium turnings. After refluxing the mixture for several hours, a part of the ether was removed by distillation. The heavy salt precipitate was filtered and the precipitate was washed three times with dry ethyl ether. The combined filtrate and washings were concentrated by distillation, removing first the ethyl ether, then the methyltrichlorosilane and, finally, under vacuum, the silane reaction product. Upon purification by redistillation, relatively pure-pchlorophenylmethyldichlorosilane was obtained having a boiling point of 62 C. to 63 C. at 1 mm. pressure. Its index of refraction and density were: n 1.5332, D 1.2998.

Analysis.Calcd. for C H Cl Si: C, 37.25; H, 3.10, Si, 12.42. Found: C, 37.26, H, 3.32; Si, 12.15.

The p-chlorophenylmethyldichlorosilane was subjected to hydrolysis and condensation by following the procedure of Example II. p-Chlorophenylmethylpolysiloxane was obtained as a thick viscous oil. The coefficient of friction of the liquid was 0.133 and its average wear-rate in a Falex machine was 3 units per hour.

It was a highly stable liquid. A sample, exposed to the air, was heated at 175 C. for over twenty days before gellation took place. The addition of 0.1% of the metal chelate, copper acetyl acetonate, retarded gellation so that the liquid stood 175 C. in air for over a hundred twenty-five days without gelling, at which time the test was discontinued.

EXAMPLE VII Preparation of p-fluorophenyldimiethylethoxysilane and its disiloxane product p-Bromofluorobenzene was substituted in the process of Example I for the pdibromo=benzene as set forth therein. After distillation and purification of the reaction products, substantially pure p-fiuorophenyldimethylethoxysilane was obtained with the following constants: boiling point 69 C. at 6 mm. pressure, n 1.3639 and D 0.9846.

Analysis.-Calcd. for C H FSiO: C, 60.60; H, 7.57; F, 9.59. Found: C, 60.55; H, 7.35; F, 9.80.

The p-fluorophenyldimethylethoxysilane was hydrolyzed and condensed in accordance with the procedure of Ex- 6 ample II and the resulting bis (p-fiuorophenyDtetramethyldisiloxane resulting was a relatively stable liquid having the following constants: boiling point 96 C. to 98 C. at 1 to 2 mm. of pressure, n 1.4950 and D 1.0653. Analysis.-Calcd. for C1 H F Si O: Si, 17.39; F, 11.80. Found: Si, 17.20; F, 11.90.

When tested for its antifriction properties, it exhibited a coeflicient of friction of 0.20 and an average Wear-rate steel-on-steel on a Falex machine of 54.

EXAMPLE VIII Preparation of p-fluorophenylmezhyldiethoxysilane and polysiloxane products thereof A Grignard reagent compiising p-fluorophenylmagnesium bromide was added to an excess of methyltriethoxysilane and, after stirring for several hours, the mixture was permitted to stand and the liquid was decanted. The sludge was filtered and the residue washed several times with dry ethyl ether, the filtrate being added to the liquid previously decanted. The combined liquids were then subjected to fractional distillation to separate the ethyl ether and the unreacted methyltriethoxysilane. The high boiling residue was purified by redistillation to produce relatively pure p-fluorophenylmethyldiethoxysilane having a boiling point of 875 C. to 88 C. at 4 to 5 mm. of pressure. Its index of refraction and density were: 11 1.4558; D 1.0149.

Analysis.-Calcd. for C I-I FSiO C, 57.89; H, 7.45; Si, 12.28; F, 8.33. Found: C, 57.35; H, 7.62; Si, 11.94; F, 8.35.

The silane of this example was hydrolyzed and condensed in accordance with the procedure of Example II to produce p-fluorophenylmethylpolysiloxane. In tests for anti-friction properties, this polysi-loxane liquid had a coefiicient of friction, steel on steel, of 0.168 and an average, steel-on-steel, wear rate in a Falex machine of 208 units per hour.

EXAMPLE IX Average Coefficient Wear Falex R of Friction Machine Steel on (Steel on Steel Steel) Units per hour m(GF O H4 0. 16 7. IELClCuH4-. 0. 20 5. 0C1COH4. 0. 16 72 3,4Cl2CoHa 0. 137 6. X,XC12CsHs- 0. 132 5.

TABLE II.OOEFFICIENT OF FRICTION AND WEAR RATES OF POLY- SILOXANE OILS Both the disiloxanes of the type shown in Table I and the polysiloxanes shown in Table 11 having one substituted phenyl group per silicon atom wherein the substituted phenyl group comprises electronegative substituents on the phenyl group selected from chlorine, fluorine, bromine, trifluoromethyl, and halophenoxy groups, exhibit low coefficients of friction and low average wear-rate on the Falex machine. We have prepared similar compounds with an average of only one of the substituted phenyl groups for a number of silicon atoms, as for instance, one for every eleven silicon atoms, and found that they exhibited excellent antifriction properties and low rates of wear very similar to those values in these tables. Little change in the antifriction properties is exhibited in compounds wherein the ratio of the same substituted phenyl group to the silicon atoms varies from 1:1 to 1:11 and higher up to 1:50.

Mixtures of any two or more of the compounds having the substituted phenyl groups of this invention exhibit good lubrication properties. Thus, mixtures of the p-fiuorophenylmethyl silicone and m-trifiuoromethylphenylmethyl silicone, for example, are excellent lubricants.

Examples of disiloxanes having dissimilar substituents on a single substituted phenyl group are: bis(2-trifluoromethyl-3,4-difluorophenyl) tetramethyldisiloxane; bis 3 chloro-4-brornophenyl tetramethyldisiloxane; and

CH CH;

stitute somewhat better overall lubricants, it is recommended that, previous to hydrolysis or during hydrolysis, the electronegative substituted phenyl silanes having two hydrolyzable groups per silicon atom be admixed with a predetermined amount of a silane capable of furnishing end-blocking groups. For this purpose, there may be added, one or more of the following: a silane having a single hydrolyzable group, or the hydrolysis product of such a silane, such as a hexahydrocarbon substituted disiloxane. For instance, hexamethyldisiloxane is capable of furnishing two terminal trimethylsilyl groups by cleavage reaction. This will insure the condensation siloxane product containing on the average a high proportion of linear molecules terminated at each end by the trisubstituted silyl groups. Thus, a mixture of twenty mole-percent of an end-blocking silane having a single hydrolyzable group and eighty mole-percent of a chainforming silane having two hydrolyzable groups per silicon atoms, when suitably reacted, will produce polysiloxanes comprising almost entirely linear molecules having on the average ten silicon atoms in a chain. Examples of endblocking silanes that may be used in this reaction are trimethylchlorosilane, phenyldirnethylethoxysilaneand chlorophenyldimethylchlorosilane; and they may be used singly or in mixtures of two or more. Of the two organic substituents per silicon atom along the chain, from 0.02 to 1 may be substituted phenyl groups and the remainder methyl or other alkyl radicals. It will be appreciated that there will be some molecules having a greater numher and others less than this average number of silicon atoms in a chain, and that there may be a small amount of cyclic compounds resulting. If low boiling siloxane components resulting from the hydrolysis and condensa tion are undesirable, they may be removed by applying fractional distillation to the siloxane product.

The following Tables III to V illustrate the properties of a variety of polysiloxanes, prepared in accordance with the present invention, correlated to various proportions of substituted phenyl groups per silicon atom.

TABLE III Sample N0 Length (Si atoms) Molar Ratio of Monomers Average Wear Rate (Falex) Steel on Steel, Units per hour Coefficient of Friction Steel on Steel Calcd. Chain p-Brornophenylmethyldiethoxy silane Hexamethyldisiloxane Dimethyldiethoxysilane Average Gulf Mechanism B lubricating Oil Heavy duty Petroleum oil (medium Viscosity) Petr The copolymers of sample Nos. 1 to 8 were prepared by mixing the respective monomers in the indicated and following the procedure of Example II.

proportions TABLE IV Sample No.

Length (Si atoms) Molar Ratio of Monomers Average Coeflicient Wear Rate of Friction Steel on Steel Oalcd. Chain p-Chlorophenylmethyldiethoxysilane Dimethyldiethoxysilane Hexameth- Steel, Units yldisiloxane Average per hour The copolymers or sample Nos. 10 to 16 were prepared by mixing the monomers in the proportions indicated and following the procedure of Example II.

TABLE V Molar Ratio of Monomers Average Calcd. Wear Rate Chain Coeflicient (Falex) Sample No. Lengthp-Ohloro- Phenylof Friction Steel on Average phenylmethyl- Hexa- Steel on Steel, (Si atoms) methyldietoxymethyl- Steel Units per diethoxysilane disiloxane Hour silane 8 6 1 0.136 60 8 3 3 1 0.15 70 14 12 0 1 0.13 2 14 8 4 1 0.15 0. 66 14 4 8 1 0.228 153 14 2 10 1 0. 343 over 300 14 1 11 1 0. 368 Over 300 14 0 12 1 0. 368 00 in the proportions indicated and following the procedure of Example II.

The compound x,x-dichlorophenylmethyldichlorosilane having an average R per Si of 2, and an average of 2 hydrolyzable chlorine groups per silicon atom was prepared by adding one equivalent of methyl magnesium bromide to x,x-dichlorophenylthichlorosilane and the resulting product was hydrolyzed, without isolation, by slow addition to a large excess of water. The resulting polysiloxane was easily separated from the aqueous solution and freed from the ether. The polysiloxane product is identified as sample No. 40. Portions of this polysiloxane product were equilibrated (75% sulfuric acid) with varying amounts of bis(p-chlorophenyl)tetramethyldisiloxane as an end-block agent, the respective proportions being set forth in Table VI. The lubricating properties of the respective polysiloxanes are also shown.

TABLE VI.COMPOSITION AND LUBRICATING PROPER- The hexamethyl disiloxane monomer used in the preparation of sample Nos. 1 to 8, 10 to 16 and 21 to 26 in Tables III, IV and V, cleaved during the reaction to form two monovalent radicals comprising trimethyl silyl groups and formed the terminal end-blocking groups on the siloxane copolymer chains.

Mixtures of polysiloxanes may be prepared to produce compositions having predetermined properties difiering from those possessed by the individual siloxanes such as in any of the examples or the tables. Thus mixtures of any two or more polysiloxanes having substituted phenyl groups, wherein the substituents are the electronegative radicals defined herein, may be prepared. Thus any two or more of the siloxanes, such as sample Nos. 2 to 7 of Table III or Nos. 10 to 16 of Table IV or Nos. 21 to 26 of Table V may be admixed. The coefficient of friction and wear rate of the mixtures will usually assume values between the highest and lowest values for these properties of the individual components of such mixtures. In many cases the values for coefiicient of friction and wear rate will approach that of the lowest of the values exhibited by the components of the mixture.

Mixtures of one or more disiloxanes, typified by Table I, or one or more polysiloxanes, typified by Table II, or one or more copolymer siloxanes, typified by Tables III, IV, V and VI, or any combination of disiloxanes, polysiloxanes or copolymer siloxanes may be prepared in suitable proportions. Fluids of a wide range of viscosities, coefiicients of friction and wear rates, as well as other characteristics, are thus made available.

The polysiloxanes of this invention having an average of three or more silicon atoms per molecule with up to one of the substituted phenyl radicals per silicon and the other organic substituents on silicon, aside from oxygen, being either methyl or phenyl and methyl radicals are liquid at room temperature, irrespective of the number or position of the electronegative substituents on the substituted phenyl radical. Disiloxanes of the formula:

where R represents at least one electronegative radical selected from the group consisting of chlorine, bromine, fluorine, trifluoromethyl and halophenoxy radicals and n is a number of 1 to 5, are liquids at room temperature when n is 1 and 2 regardless of the type or position of the R radical on each phenyl radical. When from three to five of the electronegative radicals are present on one or both of the phenyl radicals of the disiloxane, liquids are usually obtained, though low melting point crystalline solids may result in some cases depending on the kind, the number and position of the electronegative radicals on the phenyl radical. The low melting temperature disiloxane solids are useful as greases, either when used alone, or combined with various solid lubricants such as graphite, molybdenum disulfide or lithium soaps. These low melting disiloxane solids may be readily dissolved in the liquid disiloxanes or the liquid polysiloxanes of this invention or in dimethyl silicone oils or other siloxane fluids and the resulting solution may be used as a liquid lubricant with satisfactory results.

We have found no substantial difference in the lubricating properties of the di(substituted phenyl) tetrarnethyl disiloxanes having one, two, three or more of the electronegative groups substituted on each phenyl radical, outside of slight normally expected variations due to the kind of the radical and its position. Accordingly, for lubricating purpose it is expedient to employ the disiloxanes disclosed herein with only one or two substituents on each phenyl group inasmuch as a higher degree of substitution on phenyl ordinarily gives no further advantage.

For improving the stability of the fluid siloxanes of the present invention, We have found it desirable to incorporate therein metal chelates as disclosed in US. Patent 2,465,296, assigned to the assignee of the present invention. These metal chelates comprise the reaction product of a metal with a compound having the formula where X is selected from the group consisting of hydrocarbon, alkoxy and hydrocarbon substituted amino radicals and Y is selected from the group consisting of oxygen and hydrocarbon substituted imino radicals, the subill.

stituted imino radical being present only when X is a hydrocarbon radical. For example, we found that the time to produce gelation of the siloxanes of Examples V and II when heated to 175 C. and exposed to the atmosphere was increased by more than 6 times (at which time the tests were discontinued) by the addition of 0.1% of copper acetyl acetonate, while 0.02% of cadmium ethyl acetoacetate increased the resistance to gelation by a factor of more than 9.

The fluid polysiloxanes of the present invention may be admixed with from 1% to 100% based on the weight of the siloxane, of one or more solid lubricant materials such, for example, as finely divided molybdenum disulphide (passing through a screen finer than 100 mesh and preferably ball milled to a colloidal size of less than 20 microns), silver sulfate, tungsten sulphide, or boron nitride to enable better lubrication to be secured from the fluids or, if suflicient of the solid is present, they may be used as greases or as pasty metal drawing and shaping compounds. Other fillers which may be employed in preparing greases from the liquid polysiloxanes are colloidal silica, talc, titanium dioxide, mica powder, zinc oxide, and graphite.

We have found that our substituted phenyl siloxanes, wherein the aforementioned electronegative groups are substituted on phenyl, may be advantageously combined with liquid polysiloxanes embraced by the general formula [R SiO],, or R Si,,O where R represents the same or difierent monovalent hydrocarbon radicals selected from the class consisting of lower alkyl, oycloaryl, aryl, alkaryl and aralkyl radicals of which at least mole percent are phenyl and simple alkyl hydrocarbon substituted phenyl radicals such as tolyl and xylyl. Exceptionally good results have been secured with polysiloxanes having a majority or all of the KS being either methyl or phenyl and methyl groups, the phenyl radical comprising 10 mole percent of the total. The n represents a number whose value is 3 and higher, while a represents a number whose value is at least 2. Examples of R are methyl, ethyl, propyl, decyl, cyclohexyl, methylcyclohexyl, phenyl, benzyl, tolyl and xylyl. As little as 0.1% by weight of the substituted phenyl siloxanes added to any one or mixtures of two or more of such other polysiloxanes containing phenyl or alkyl hydrocarbon substituted phenyl radicals produces an improvement in coefficient of friction and reduced wear rate on the Falex test. Any proportion of the substituted phenyl siloxane to such other polysiloxane up to 100% of the former being present may be employed to advantage. As an example, a liquid phenylmethyl silicone fluid commercially available, having a viscosity of 70 centistokes and a coefllcient of friction of 0.40, steel on steel, was mixed with 3% of its weight of bis(p-bromophenyl)tetramethyl disiloxane. The combination exhibited a coefficient of friction of 0.198. The same phenylmethyl silicone with 10% of bis(p-chlorophenyl) tetramethyldisiloxane added gave a wear rate of 567.

The structures and proportions of the various methyl and other polysilanes, having no substituted phenyl with electronegative radicals as substituents, suitable for use in producing the combination are set forth in Ford and Wenzel Patent 2,456,496, and in Patents 2,398,187; 2,483,158; 2,457,777; 2,468,869; 2,466,642 and 2,469,- 888. Exceptional results are secured by combining the substituted phenyl siloxanes of the present invention with any or all of the phenyl methyl polysiloxanes having the R [ant] l.

C2H5 [an] a z where R and R represents the same or different monovalent hydrocarbon radicals as above defined and x in Formula (a) represents a whole number of at least one while in Formulas (b) and (c) x represents a whole number of a value of at least 3, and a major proportion of the R and R radicals are methyl and phenyl or alkyl hydrocarbon substituted phenyl. In the Formula (a) R may be methyl and at least one R may be phenyl. Among the advantages to be secured by combining liquid phenyl methyl polysiloxanes with the substituted phenyl siloxanes of the present invention are the low change in viscosity with temperature of the former with the outstanding lubricity of the latter.

The following are examples of suitable compositions embodying a proportion of the substituted phenyl siloxane fluids having the electronegative substituents on phenyl and other liquid siloxanes, in which all parts are by weight:

A. of 1,1,3-trimethyl triphenyl disiloxane, and

10% of bis(pfluorophenyl)tetramethyldisiloxane of 1,3-hexamethyl-Z-methyl-Z-phenyl-trisiloxane, and

5% of bis(m-chlorophenyl) tetramethyldisiloxane 95% of a phenylmethyl silicone oil of a viscosity of 200 centistokes and 5% of the dichlorophenylmethylpolysiloxane oil of Table II--third example.

. 98% of a methyldodecylphenylsiloxane oil containing one phenyl and one dodecyl group per six methyl groups, and 2% trifluoromethylphenylmethylpolysiloxane of Table III-first example.

While the compositions of the present invention are particularly suitable for application to bearing surfaces to reduce friction and wear, as, for example, in electrical meters, motor and machinery bearings, automobile engines, and the like, they are also suitable for use in hydraulic mechanisms of all kinds. Thus they may be used in hydraulic brake mechanisms, torque converters, shock absorbers, servo-mechanisms, hydraulic presses and similar hydraulic machinery. In such hydraulic machines, the machine comprises a casing with in which is disposed one movable member to which a force is applied to cause it to move and the force or movement is transmitted to another member by means of an interposed fluid. In hydraulic machines provided with the fluid substituted phenyl siloxanes of the present invention, particularly where closely fitting parts are moved with respect to one another, lower rates of wear can be secured than with petroleum oils or previously known fluid siloxanes, thereby prolonging the operating life of the apparatus, rendering the efliciency and reliability to be maintained and greater variations in operating temperatures to be met Without affecting the ease or efiiciency of the operation of the machines.

The organosiloxane fluids have utility as surface coatings in molding and forming dies for sheet metal, plastics, powdered metals, and the like, where they will serve both for improving the ease of drawing of the metal and preventing its being scored, as well as to enable the release of and parting of molded plastics, powdered metal compacts, and drawn metal shapes from the molds and dies.

Since certain obvious changes may be made in the above procedures and different embodiments of the invention could be made without distinguishing from the scope thereof, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. A disiloxane having two methyl groups attached to each of the two silicon atoms and a chlorophenyl radical attached to each of the silicon atoms, the chlorophenyl radical having from one to two chlorine groups substituted in the ring.

2. Bis(chlorophenyl)tetramethyldisiloxane.

3. Bis(dich1orophenyl)tetramethyldisiloxane.

References Cited in the file of this patent UNITED STATES PATENTS McGnegor et al. Apr. 9, Rust et al. Aug. 19, Daudt May 3, Sprung et al. Sept. 27, Hyde Oct. 25, Burkhard July 17, Kohl Oct. 16, Frost Apr. 28, Kohl May 26, Burkhard Sept. 21, Frost et al. Aug. 6,

Claims (1)

1. A DISILOXANE HAVING TWO METHYL GROUPS ATACHED TO EACH OF THE TWO SILICONE ATOMS AND A CHLOROPHENYL RADICAL ATTACHED TO EACH OF THE SILICONE, THE CHLOROPHENYL RADICAL HAVING FROM ONE TO TWO CHLORINE GROUPS SUBSTITUTED IN THE RING.