CA1058151A - Lubricants and functional fluids containing substituted sulfolanes as seal swelling agents - Google Patents

Abstract

Title: LUBRICANTS AND FUNCTIONAL FLUIDS CONTAINING SUB-STITUTED SULFOLANES AS SEAL SWELLING AGENTS

Inventor: Frederick William Koch -Abstract of the Disclosure-.
Compositions useful as lubricants and functional fluids comprise an oleaginous liquid of lubricating vis-cosity, typically a mineral oil, and a 3-alkoxysulfolane or the like, in which the alkoxy group contains at least about 4 and preferably about 4-25 carbon atoms, as a seal swelling agent.

Description

iO5~151 This invention relates to new compositions of matter suitable for causing swelling of seals in machinery, and to methods of causing said swelling of seals. More particularly, it relates to compositions comprising an oleaginous liquid of lubricating viscosity and a substituted sulfolane of the formula wherein Rl is a hydrocarbon-based radical having at least abou~ 4 carbon atoms and each of R2 and R3 is hydrogen or a lower alkyl-based radical.
The problem of shrinkage of seals, particularly elastomeric seals, in machinery (e.g., automatic trans-missions for motor vehicles) upon contact with functional fluids is of considerable importance since such shrinkage causes leakage of the functional fluid which can lead to defective operation of the machinery, or failure to operate at all. (The term "functional fluid", as used herein, means a fluid involved in the transmission of energy, such as a lubricant, hydraulic fluid, automatic transmission fluid, heat exchange medium or the like.) To eliminate this problem, it is conventional to include in the functional fluid an additive whose presence therein causes the seal to swell. A number of such additives are known in the art, but their use has several disadvantages. For example, many of them are toxic. Moreover, they must often be used in unde-sirably large quantities in the functional fluid.
A principal object of the present invention, there-fore, is to provide new compositions of matter capable of swelling or minimizing shrinkage of seals used in machinery, and methods of causing such swelling.

1058~Sl ` A further o~ject is to provide seal-swelling lubricants and functional fluids which contain relatively non-toxic additives.
A further object is to provide lubricants and iunctional fluids containing extremely small but effective quantities of seal swelling additives.
Other objects will in part be obvious and will in part appear hereinafter.
As previously noted, the compositions of this invention comprise two components of which the ~irst is an oleaginous li~uid of lubricating viscosity. Such liquids include natural and synthetic oils and mixtures thereof, especially oils of the type useful as crankcase lubricating oils for spark-ignited and compression-ignited ~15 internal combustion engines, including automobile and truck engines, two-cycle engines, aviation piston engines, marine and railroad diesel engines, as well as gas engines, jet aircraft turbines, stationary power engines and turbines and the like. Base liquids for automatic transmission fluids, transaxle lubricants, gear lubricants, metal-working lubricants, hydraulic fluids and other lubricating oil and grease compositions are also useful for this purpose.
Natural oils include animal oils and vegetable - oils (e.g., castor oil, lard oil) as well as liquid petro-leum oils and solvent-treated or acid-treated mineral lubri-~ating oils of the paraffinic, naphthenic or mixed paraf-finic-naphthenic types; such mineral oils are preferred.
Oils of lubricating viscosity derived from coal or shale are also useful.
Synthetic lubricating oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymer-~ ` ~058151 iæed and interpolymerized olefins le.g., polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlori-nated polybutylenes, poly(l-hexenes), poly(l-octenes), . poly(l-decenes), etc. and mixtures thereofl; alkylbenzenes ~e.g., dodecylbenzenes, tetradecylbenzenes, dinonyl-benzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls, etc.), ~- alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof and the like. --Alkylene oxide polymers and interpolymers and .
derivatives thereof where the terminal hydroxyl groups have ~ ~ been modified by esterification, etherification, etc. con-;~ ~ stitute another class of known synthetic oils. These are I5 exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxi&e, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having an average molecular weight of 1000, diphenyl ether of polyethylene glycol , ~20 having a molecular weight of 500-1000, diethyl ether of ; polypropylene glycol having a molecular weight of 1000-1500, - etc.) or mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C3-C8 fatty acid esters, esters, or the Cl 3 OXO acid diester of tetraethylene glycol.
Another suitable class of synthetic oils comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, .

` ~()S815~
hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, p~opylene glycol, etc.). Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl ; 5 fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid, and the like.
Esters useful as synthetic oils also include those made from C5 to Cl 2 monocarboxylic acids and polyols ~ and polyol ethers such as neopentyl glycol, trimethylol-.
propane,~pentaerythritol, dipentaerythritol, tripentaeryth-~ 15 ritol, etc.
; ~ - - Siiicon-based oils such as the polyalkyl-, .- ~
polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils comprise another useful class of synthetic oils [e.g., tetraethyl silicate, tetraisopropyl silicate, , - tetra-(2-ethylhexyl) silicate, tetra-(4-methyl-2-ethylhexyl) silicate, tetra-(p-tert-butylphenyl) silicate, hexyl-- (4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxanes, poly(methylphenyl)siloxanes, etc.]. Other synthetic oils - include liquid esters of phosphorus-cor.taining acids (e.g.,-tricresyl phosphate, trioctyl phosphate, diethyl ester of . decylphosphonic acid, etc.), polymeric tetrahydrofurans and the li~e.
- Unrefined, refined and rerefined oils ~and mixtures of each with each other) of the type disclosed hereinabove can be used in the compositions of the present invention.
Unrefined oils are those obtained directly from a natural or `'` ~()58~S~

synthetic source without further purification treatment.
For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from di~-tillation or ester oil obtained directly from an esterifi-cation process and used without further treatment would bean unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those of s~ill in the art such as solvent extraction, acid or base extraction, filtration, percolation, etc. Rerefined oils are obtained - by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such refined oils are also known as reclaimed or 1J rep~ocesscd GilS and GCt2n aï c ad~iticnally process2d by techniques directed to removal of spent additives and oil breakdown products.
The substance which serves as a seal swelIing component in the caffipositions of this invention is a sub-stituted sulfolane having the above formula. (When used herein, the singular form "a", "an" and "the" include theplural unless the context clearly dictates otherwise; thus, for example, "a compound" includes a mixture of compounds.) In the formula, Rl is a hydrocarbon-based radical having at least about 4 carbon atoms. The term "hydrocarbon-based radical", when used herein, denotes a radical having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character within the context of this invention. Such radicals include the follow-ing: .

1~581Sl (1) Hydrocarbon radicals; that is, aliphatic,(e.g., alkyl or alken~l), alicyclic (e.g., cycloalkyl or cycloalkenyl), aromatic, aliphatic- and alicyclic-substi-tuted aromatic, aromatic-substituted aliphatic and alicyclic radicals, and the like. Such radicals are known to those skilled in the art; examples include butyl, pentyl, hexyl, octyl, decyl, dodecyl, eicosyl, decenyl, cyclohexyl, phenyl, tolyl, heptylphenyl, isopropenylphenyl and naphthyl (all isomers of such radicals being included when more than one isomer is possible).

(2) Substituted hydrocarbon radicals; that is, radicals containing non-hydrocarbon substituents which, in the context of this invention, do not alter the predominantly hydrocarbon character of the radical. Those skilled in the art will be aware of suitable substituents; examples are O O O

halo, nitro, cyano, RO-, RC-, ROC-, R2N-, R2NC-, RS-, Rl-, O
O O
RS- and ROS- (R being hydrogen or a hydrocarbon radical).
O O

(3) Hetero radicals; that is, radicals which, while predominantly hydrocarbon in character within the context of this invention, contain atoms other than carbon present in a chain or ring otherwise composed of carbon atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, oxygen, nitro-gen and sulfur.

' ` 1058151 ;In general, no more than about three substitu-ents or hetero atoms, and preferably no more than on~, will be present for each 10 carbon atoms in the hydrocar-bon-based radical.
Terms such as "alkyl-based radical" and the like have meanings analogous to the above with respect to alkyl radicals and the like.
The preferred substituted sulfolanes are those in which Rl is a hydrocarbon radical, usually one which is free from acetylenic unsaturation and which contains about

4-100 carbon atoms. Examples (all isomers being included) are butyl, amyl, hexyl, octyl, decyl, dodecyl, eicosyl, triacontanyl, buteny~l, dodecenyl, phenyl, naphthyl, tolyl, dodecylphenyl, tetrapropene-alkylated phenyl, phenethyl, cyclohexyl and methylcyclohexyl. Alkyl radicals having about 4-25 and usually about 4-10 carbon atoms are - especially preferred.
Each of R2 and R3 is hydrogen or a lower alkyl-based (and usually a lower alkyl) radical, the word "lower"
denoting radicals containing up to 7 carbon atoms. Examples of lower alkyl radicals (all isomers being included, but especially the straight chain radicals) are methyl, ethyl, propyl, butyl and hexyl, with methyl being preferred. ~lost often, one of R2 and R3 is hydrogen and the other (usually R3) is hydrogen or methyl. Both are preferably hydrogen.
The preferred substituted sulfolanes for use in the compositions of this invention are those in which R2 and R3 are hydrogen and Rl is either the isodecyl radical or a combination of the isobutyl radical with a mixture of primary amyl radicals, the iso~utyl material comprising about 25-75% (by weight) of said combination.

--7~

'` lOSt~5~ .
The above-described substituted sulfolanes com-prise a class of compounds which is known in the art.
They may be prepared by the reaction o 3-sulfolene or a substituted derivative thereof with an organic hydroxy compound, ordinarily an alcohol, This method for their preparation is described, for example, in U.S. Patent 2,393,~25, and in Data Sheet DS-58:3 of Shell Development Company entitled "3-Sulfolene". The 3-sulfolenes may be prepared by reaction of sulfur dioxide with a conjugated diene such as butadiene or isoprene.
The compositions of this invent-on which are useful as functional fluids contain a minor amount of sub-stituted sulfolane effec~ive to cause swelling of seals.
That amount is usually about 0.05-20.0 parts (by weight), preferably about 0.1-5.0 parts, per 100 parts of oil.
However, the invention includes additive concentxates com-prising a diluent (typically an oleaginous liquid of lubri-cating viscosity) and the substituted sulfolane, the latter comprising up to about 90~ of the weight o the concentrate.
Such concentrates may be diluted with the oleaginous liquids as described hereinabove, as is well known in the art, to produce functional fluids.
The present invention also contemplates functional fluids and concentrates containing other additives in com-bination with the substituted sulfolane. Such additives include, for example, detergents and dispersants of the ash-containing or ashless type, corrosion- and oxidation-inhibi-ting agents, pour point depresging agents, extreme pressure agents, viscosity index improvers, color stabilizers and anti-foam agents.
- The ash-containing detergents are exemplified by oil-soluhle neutral and basic salts of alkali ox alkaline '` 1058151 `
earth metals with sulfonic acids, carboxylic acids, or organic phosphorus acids characterized by at least one direct carbon-to-phosphorus linkage such as those prepared by the treatment of an olefin polymer (e.g., polyisobutene having a molecular weight of 1000) with a phosphorizing agent such as phosphorus trichloride, phosphorus heptasul-fide, phosphorus pentasulfide, phosphorus trichloride and sulfur, white phosphorus and a sulfur halide, or phosphoro-thioic chloride. The most commonly used salts of such acids - 10 are those of sodium, potassium, lithium, calcium, ma~nesium, strontium and barium.
The term "basic salt" is used to designate metal salts wherein the metal is present in stoichiometrically larger amounts than the organic acid radical. The commonly lS ~ employed methods for preparing the basic salts involve heating a mineral oil solutLon of an acid with a stoichio-metric excess of a metal neutralizing agent such as the metal oxide, hydroxide, carbonate, bicarbonate, or sulfide : . .
~ at a temperature above 50C. and filtering the resulting , - :
~mass. The use of a "promoter" in the neutralization step to aid the incorporation of a large excess of metal likewise is known. Examples of compounds useful as the promoter - include phenolic substances such as phenol, naphthol, ~ `
- ~ ~ alkylphenol, thiophenol, sulfurized alkylphenol, and con-densation products of formaldehyde with a phenolic sub-:
stance; alcohols such as methanol, 2-propanol, octyl alcohol, - cellosolve, carbitol, ethylene glycol, stearyl alcohol, and cyclohexyl alcohol; and amines such as aniline, phenylene-diamine, phenothiazine, phenyl-~-naphthylamine, and dodecyl-amine. A particularly effective method for preparing the iO58~5~
basic salts comprises mixing an acid with an excess of a basic alkaline earth metal neutralizing agent and at least one alcohol promoter, and carbonating the mixture at an elevated temperature such as 60-200C.
Ashless detergents and dispersants are illustra-ted by the interpolymers of an oil-solubili~ing monomer, e.g., decyl methacrylate, vinyl decyl ether, or high molecu-lar weight olefin, with a monomer containing polar sub-stituents, e.g., aminoalkyl acrylate or poly-(oxyethylene)-substituted acrylate; the amine salts, amides, and imides of oil-soluble ~onocarboxylic or dicarboxylic acids such as stearic acid, oleic acid, tall oil acid, and high molecular weight alkyl or alkenyl-substituted succinic acid. Especial-ly useful as ashless detergents are the acylated polyamines and similar nitrogen ~mpounds containing at least ~bout 54 carbon atoms as described in U.S. patent 3,272,746;
reaction products of such compounds with other reagents including boron compounds, phosphorus compounds, epoxides, aldehydes, organic acids and the like; and esters of hydro-carbon-substituted succinic acids as described in U.S.
patent 3,381,022.
Extreme pressure agents ana corrosion-inhibiting and oxidation-inhibiting agents are exemplified by chlor-inated aliphatic hydrocarbons such as chlorinated wax;
organic sulfides and polysulfides such as benzyl disul-fide, bis(chlorobenzyl) disulfide, dibutyl tetrasulfide, sulfurized methyl ester of oleic acid, sulfurized alkyl-phenol, sulfurized dipentene, and sulfurized terpene; phos-phosulfurized hydrocarbons such as the reaction product of a phosphorus sulfide with turpentine or methyl oleate; phos-phorus esters including principally dihydrocarbon and ` 105~5~
trih~drocarbon phosphites such as dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentyl phenyl phosphite, dipentyl phenyl phosphite, tridecyl phosphite, distearyl phosphite, dimethyl naphthyl phosphite, oleyl 4-pentylphenyl phosphite, polypropylene (molecular weight S00)-substituted phenyl phosphite, diisobutyl-substituted phenyl phosphite; metal thiocarbamates, such as zinc dioctyldithiocarbamate, and barium heptylphenyl dithio-~arbamate; Group II metal phosphorodithioates such as zinc dicyclohexylphosphorodithioate, ~inc dioctylphosphorodi-thioate, barium di(heptylphenyl)phosphorodithioate, cadmium dinonylphosphorodithioate, and the zinc salt of a phosphoro-dithioic acid produced by the reaction of phosphorus penta-sulfide with an equimolar mixture of isopropyl alcohol and n-hexyl alcohol.
Typical compositions according to this invention - are listed in the following table. All amounts other than those for mineral oil are exclusive of oil used as diluent.
The substituted sulfolanes are those of the above structural formula wherein Rl is as listed and R2 and R3 are each hydrogen.

, ~058~5~
;
. Parts by ~eight In~xedient A B C D
Mineral oil (SAE lOW-40 base) ~ -- 90.29 85.83 Mineral oil (automatic trans-mission fluid base) ~2.91 94.95 -~- ---Substituted sulfolane, Rl =
isodecyl --- 0.50 2.00 2.00 Substituted sulfolane, Rl = mixture of isobutyl and primary amyl 1.00 --- --- ---Reaction product of ethylene polyamine with pol.yiso- .
butenyl succinic ~nhydride 3.09 1.71 -~
Borated reaction product of ethylene polyamine with polyisobutenyl succinic anhydride 0.68 0.67 0.74 ---Pentaerythritol ester of polylsob~tenyl su CGi nic acid . . --- --- --- 2.35 Reaction product of penta-erythritol and ethylene polyamine with polyiso-butenyl succinic anhydride --- --- 2.30 --- -. Basic calcium petroleum sulfonate -. -~ - 0.75 Tetrapropenyl succinic acid --- --- 0.34 ---Zinc isooctylphosphoro-dithioate 0.66 --- --- ---Zinc salt of mixed iso-butyl- and prim-amyl-phosphorodithioic acids --- --- --- 1.32 Dialkyl (~-hydroxy-Cl 4 - 1 6 alkyl) phosphonate 0.13 --- --- ---Phenyl Cl 4 - 1~ dialkyl phosphite --- 0.20 --- ---N-tallow diethanolamine 0.10 --- --- ---N-dodecyl dipropanolamine 0.04 --- --- ---Diphenylamine-based anti-oxidant 0.20 0.50 -~

105815~
Parts by we,ight In redient A B C D
g Hindered phenol antioxidant -~- --- 0.50 ---Sulfurized alkyl cyclo-hexenecarboxylate --- --- 1.33 ---Sulfurized fatty ester-fatty acid-olefin mixture --- 0.30 --- ---Styrene-butadiene copolymer --- --- 2.50 ---Styrene-alkyl maleate copolymer 1.19` 1.17 --- ---Polyacrylate viscosity index improver --- --- --- 7.75 Silicone anti-foam agent 0.020.02 0.01 0.01 .

Claims (23)

What is claimed is:

1. A composition comprising an oleaginous liquid of lubricating viscosity and a substituted sulfolane of the formula wherein R1 is a hydrocarbon-based radical having at least about 4 carbon atoms and each of R2 and R3 is hydrogen or a lower alkyl-based radical.

2. A composition according to claim 1 wherein said substituted sulfolane is present in a minor amount effective to cause swelling of seals in machinery.

3. A composition according to claim 2 wherein R2 and R3 are hydrogen.

4. A composition according to claim 3 wherein R3 is an alkyl radical having about 4-25 carbon atoms.

5. A composition according to claim 4 wherein the oleaginous liquid is a mineral oil.

6. A composition according to claim 5 wherein R1 is the isodecyl radical

7. A composition according to claim 5 wherein R1 is a mixture of the isobutyl and primary amyl radicals.

8. A composition according to claim 4 wherein the oleaginous liquid is a synthetic oil.

9. A composition according to claim 1 which comprises an additive concentrate containing said substituted sulfolane in an amount up to about 90% by weight.

14 0. A composition according to claim 9 wherein R2 and R3 are hydrogen.

11. A composition according to claim 10 wherein R1 is an alkyl radical having about 4-25 carbon atoms.

12. A composition according to claim 11 wherein the oleaginous liquid is a lubricating oil.

13. A composition according to claim 12 wherein R1 is the isodecyl radical.

14. A composition according to claim 12 wherein R1 is a mixture of the isobutyl and primary amyl radicals.

15. A composition comprising a major amount of a lub-ricating oil and a minor amount, effective to cause swelling of seals in machinery, of 3-isodecoxysulfolane.

16. A method of causing swelling of seals in machinery which comprises contacting said seals with a composition com-prising a major amount of an oleaginous liquid of lubricating viscosity and, dissolved or stably dispersed therein, a minor amount, effective to swell said seals, of a substituted sulfolane of the formula wherein R1 is a hydrocarbon-based radical having at least about 4 carbon atoms, each of R2 and R3 is hydrogen or a lower alkyl-based radical, and X is oxygen.................................. .

1 . A method according to claim 16 wherein R2 and R3 are hydrogen.

18. A method according to claim 17 wherein R1 is an alkyl radical having about 4-25 carbon atoms.

19. A method according to claim 18 wherein the oleaginous liquid is a mineral oil.

20. A method according to claim 18 wherein R1 is the isodecyl radical.

21. A method according to claim 18 wherein R1 is a mixture of the isobutyl and primary amyl radicals.

22. A method according to claim 18 wherein the oleaginous liquid is a synthetic oil.

23. A method of causing swelling of seals in automatic transmissions of motor vehicles which comprises contacting said seals with a composition comprising a major amount of a lubricating oil and a minor effective amount of 3-isodecoxy-sulfolane.