DE69307931T2 - METHOD FOR SUPPRESSING THE FOG OF INDIVIDUAL USE OF LUBRICATING OIL - Google Patents

Abstract

There is disclosed a method of suppressing misting or spatting from an oil-containing functional fluid, such as a chain saw lubricant, by blending with the functional fluid a mist suppressing effective amount of a copolymer of a C3 or C4 alpha-monoolefin and at least one other alpha-monoolefin having from 5 to about 20 carbon atoms, said copolymer having a viscosity average molecular weight of from about 500,000 to about 10 million.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

This invention relates to a method for suppressing mist from a single-use lubricating oil such as rock drilling oils, agricultural spray oils, chain saw oils, ammonium nitrate fuel oil disintegrants, sheet metal drawing lubricants and the like. More particularly, this invention relates to the addition of a mist suppressing amount of a high molecular weight copolymer prepared from alpha-monoolefins having from 3 to 20 carbon atoms to a single-use lubricating oil such as a chain saw lubricating oil composition.

2. State of the art

Oil-containing compositions such as chain saw lubricants generally comprise a lubricating oil component and a tackifier component which serves to prevent the compositions from misting or spraying off the end of the chain during use. Known chain saw lubricant compositions, such as those described in U.S. Patent No. 4,740,324, comprise tackifier components such as polyethylene glycol or polyacrylamide, each of which has a molecular weight of 1 million or more, or rosin-containing resins such as gum rosin obtained from balsam of turpentine, wood rosin obtained by solvent extraction of rootstocks, and tall oil rosin obtained by fractional distillation of tall oil.

The use of an anti-mist additive in various other lubricating oil compositions has also been described. For example, American patents US-A-3,929,652 and 4,210,544 relate to dual-purpose cutting oils which serve as high performance cutting oils and as machine lubricants and which comprise a base oil, an extreme pressure agent, a copper corrosion inhibitor and preferably a copolymer of ethylene and Propylene as an anti-fog additive. Particularly preferred anti-fog copolymer additives, as described, have a molecular weight in the range of 70,000 to 100,000 and a propylene content of 35 to 50%.

British Patent GB-A-1 525 599 describes a metalworking lubricating oil composition containing a major amount of an oil of lubricating viscosity and a minor amount, sufficient to prevent the composition from misting during use, of at least one oil-soluble ethylene copolymer having an average viscosity molecular weight in the range of 130,000 to 250,000. The ethylene copolymer is derived from the copolymerization of ethylene with a heavier olefin selected from terminally unsaturated straight chain monoolefins having 3 to 12 carbon atoms, α-phenyl-1-alkenes having 9 or 10 carbon atoms, 2-norbornene, terminally unsaturated nonconjugated diolefins having 5 to 8 carbon atoms, dicyclopentadiene, 5-methylene-2-norbornene, and mixtures thereof. Preferably, the heavier olefin is propylene and the molar ratio of ethylene to the heavier olefin in the copolymer is in the range of 1:3 to 3:1.

American Patent US-A-3,919,098 relates to metalworking compositions having improved low-mist properties. The disclosed compositions comprise a major amount of a hydrocarbon oil and a minor amount of an anti-mist additive selected from polyisobutylene, poly-n-butene, and mixtures thereof. The anti-mist additive, as described, has a viscosity average molecular weight of from 0.3 to 10 million.

The American patent US-A-3 805 918 relates to mist-forming oil lubrication systems that pneumatically distribute fine droplets of an oil composition onto surfaces of various machine elements to be lubricated. The oil compositions described in this patent comprise a small amount of specified polyolefins in order to reduce the amount of mist scattered during the lubrication process. The polyolefins which have been described are C2Cx copolymers of ethylene having a viscosity average molecular weight of greater than 5,000. The polyolefins contain from 40 to 80 mole percent ethylene and the units defined as Cx are derived from a C3 to C12 monoolefin. The preferred polyolefins are ethylene/propylene copolymers.

American Patent US-A-4 105 569 relates to yarn finishes, particularly of the winding oil type, comprising a viscosity index improver such as a polymethacrylate, a polyalkylstyrene, an ethylene/propylene copolymer or a polyisobutylene. The viscosity index improver provides improved adhesion of the finish to the yarn being treated, less tendency to drip and less finish "shed" during high speed winding of the treated yarn. The yarn finish formulations may also contain a polysiloxane which reduces the surface tension of the finish and prevents misting during high speed winding.

American patent US-A-4 400 281 relates to the improvement of the adhesive and cohesive properties of a textile lubricant composition containing mineral oil, fatty esters or natural oils and an emulsifier by adding to the textile lubricant composition 0.01 to 10% by weight of a polymer having a molecular weight of 1 to 10 million comprising either homopolymer of normal C6 to C4 α-monoolefins or copolymers of two or more normal C4 to C20 α-monoolefins. Copolymers that can be added to the textile lubricant composition include copolymers of butene-1 and at least one C5 to C14 alpha-monoolefin such as hexene-1, octene-1, decene-1, dodecene-1 and/or tetradecene-1. The addition of the polymer improves the adhesion of the lubricant composition without reducing its lubricity and reduces the tendency of the composition to string.

American Patent US-A-4,173,455 relates to hydrous diesel fuel emulsions containing diesel fuel, a specified emulsifier, an anti-fogging agent and water. The anti-fogging agent is added to the fuel emulsion to prevent the emulsion from being atomized upon impact when a fuel container ruptures. The anti-fogging agent is believed to cause the fuel emulsion to exit the ruptured fuel container in "sheets" and "strings of beads" which do not provide enough surface area for explosive combustion. The anti-fogging agents to be used in the diesel fuel emulsion are described as long chain, high molecular weight polymers which have been developed to improve the flow of oil through pipelines. In column 3, lines 32 to 35 of this patent it is stated that the antifogging agents used by the applicant were proprietary compositions obtained under the trade name CDR or AM-1 (from Continental Oil Company) and that the composition of the antifogging agents was unknown. Although the exact identity of the CDR or AM-1 polymer compositions is unknown to the present applicant, the compositions are believed to comprise homopolymers of octene-1.

American patents US-A-4 384 089 and 4 527 581 relate to the reduction of the friction loss which normally occurs in hydrocarbon-carrying lines during the transport of hydrocarbon liquids, which can be reduced by adding small amounts of certain copolymers to the hydrocarbon liquids. The copolymers have been described in American patent US-A-4 384 089 as comprising copolymers of two or more α-monoolefins having 3 to 20 carbon atoms, and have been described in American patent US-A-4 527 581 as comprising copolymers of butene-1 and another α-monoolefin having 5 to 20 carbon atoms. Neither of these patents proposes the Use of the copolymers as anything other than hydrocarbon oil pipeline friction reducing agents.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method of imparting elasticity or elastic deformability to a lubricating oil composition which is subject to shear, centrifugal or gravitational induced forces which cause the fluid to separate either from itself or from the surface to which it has been applied.

Another object is to increase the cohesive and adhesive strength of a lubricating oil composition by adding a high molecular weight α-olefin copolymer tackifier additive.

Yet another object is to provide a lubricating oil composition suitable for single-use (disposable) applications such as lubricating chain saw links and joints, wherein the lubricating oil is prevented from misting or splashing by adding a mist suppressing amount of a copolymer prepared from at least two α-monoolefins having 3 to 20 carbon atoms and having a viscosity average molecular weight of 500,000 to 10 million.

Yet another object of the present invention is to provide lubricating oil compositions, such as chain saw lubricating oil compositions, containing a mist suppressing amount of a copolymer prepared by copolymerizing a C3 or C4 monoolefin with at least one alpha monoolefin having from 5 to 20 carbon atoms, and to provide a method of lubricating metal surfaces with these compositions.

These and other tasks are solved by providing lubricating oil compositions with a larger amount of a base oil component and a minor, fog suppressing amount of a copolymer component derived from at least one monoolefin selected from propylene and butene-1 and an additional α-monoolefin having from 5 to 20 carbon atoms. According to preferred embodiments of the invention, the fog suppressing copolymer is prepared by copolymerizing butene-1 with at least one other α-monoolefin having from 5 to 20 carbon atoms. Preferably, the α-monoolefins copolymerized with the butene-1 are those having from 6 to 14 carbon atoms, with hexene-1, octene-1, decene-1, dodecene-1 and tetradecene-1 being the most preferred comonomers. The copolymeric mist suppressant which must be blended with the base oil component desirably has a viscosity average molecular weight above 100,000, e.g., from 100,000 to 20 million, and generally comprises from 10 to 90 mole percent of C3 or C4 hydrocarbon units and from 90 to 100 mole percent of units derived from other C5 to C20 alpha-monoolefins.

The copolymer agent is added to the oil-containing functional fluid at a concentration effective to produce the desired fog suppression. In preferred embodiments of the invention in which propylene or butene-1 has been copolymerized with a C6 to C14 alpha-monoolefin, the copolymeric fog suppressant contains from 25 to 75 mole percent of hydrocarbon units derived from C3 or C4, is added to the functional fluid composition at a concentration of from 0.0001 weight percent (1 ppm) to 0.04 weight percent (400 ppm), and has a viscosity average molecular weight in the range of from 500,000 to 10 million. More preferred copolymers for use in the invention include those prepared from butene-1 and one or more of hexene-1, octene-1, decene-1, dodecene-1 and tetradecene-1.

DETAILED DESCRIPTION OF THE INVENTION

Although the invention is applicable to suppressing misting, also known as spattering, atomization or the like, from a wide variety of lubricating oil compositions, the following description has been limited for purposes of illustration to a description of lubricating oils particularly adapted to single-use lubrication applications such as the lubrication of chain saw links.

Surprisingly, low levels of misting or spattering result during operation of a chain saw when the chain saw lubricating fluid composition comprises a major amount of an oil of lubricating viscosity and a minor amount of a copolymer of propylene or butene-1 and at least one high molecular weight alpha-monoolefin having from 5 to 20 carbon atoms. Typically, the high molecular weight copolymer is added to the chain saw lubricating fluid at a concentration of from 0.005 to 0.04 weight percent to achieve the desired low levels of misting.

In general, extremely beneficial fog suppression has been observed when the copolymer additives have been prepared from alpha-monoolefins having from 4 to 16 carbon atoms. Particularly useful alpha-monoolefins are hexene-1, octene-1, decene-1, dodecene-1 and tetradecene-1. These monomers are preferred for use in the process of the invention because they are readily polymerized by liquid state polymerization techniques that are widely known in the art.

Examples of two-monomer component systems are propene/dodecene-1, butene-1/dodecene-1, butene-1/decene-1, hexene-1/dodecene-1 and octene-1/tetradecene-1, etc. Examples of three-component systems include butene-1/decene-1/dodecene-1, propene/hexene/dodecene-1, etc. Preferred specific monomer systems are propene/dodecene-1, butene-1/dodecene-1, butene-1/decene-1 and hexene-1/dodecene-1.

The process for copolymerizing the monomers is not part of the invention. In general, any of the various well-known processes for polymerizing alpha-monoolefins can be used. A particularly useful process is the Ziegler process, which uses catalyst systems comprising combinations of a compound of a metal of Groups IV-B, V-B, VI-B or VIII of the Periodic Table of the Elements, as found on pages 392 to 393 of the Handbook of Chemistry and Physics, 37th Edition, and an organometallic compound of rare earths or metals of Groups I-A, II-A, III-B of the Periodic Table of the Elements. Particularly useful catalyst systems are those comprising titanium halides and organoaluminum compounds. A typical polymerization process consists of contacting the monomer mixture with the catalyst in a suitable inert hydrocarbon solvent for the monomers and catalyst in a closed reaction vessel at reduced temperatures and autogenous pressure in a nitrogen atmosphere. Further details of the Ziegler process are described in American Patent US-A-3,692,676.

The total C3 or C4 hydrocarbon concentration in the anti-fog additive copolymers of the invention desirably varies from about 90 mole percent to about 10 mole percent. The factor limiting the upper concentration of propylene or butene-1 in the copolymers of the invention is solubility. As the propylene or butene-1 concentration in the polymers increases, crystallinity increases and the solubility of the copolymers in hydrocarbons decreases. Decreasing solubility has an adverse effect on the lubricant composition. The solubility limits of the copolymers will, of course, vary with different copolymer systems. In general, the practical upper propylene or butene-1 content limit for useful copolymers is about 90 mole percent. Copolymer compositions with C₃ or C₄ concentrations above about 90 mol.% have relatively poor fog suppressing properties. On the other hand, the economic The advantage of using less expensive propylene or butene-1 in preparing the copolymer composition is lost when the C₃ or C₄ hydrocarbon incorporation into the polymer falls below about 10 mole percent. In the preferred embodiments of the invention, the total C₃ or C₄ hydrocarbon concentration in the copolymer additive is about 25 to 75 mole percent and the total α-monoolefin concentration of 5 to 20 carbon atoms is about 75 to 25 mole percent. Those skilled in the art will appreciate the fact that minor amounts of the propylene or butene-1 may be introduced into the copolymer composition as a homopolymer and that the C3 or C4 hydrocarbon concentrations given above refer to the total C3 or C4 hydrocarbon content of the copolymer compositions and include propylene or butene-1 homopolymer and propylene or butene-1 present in copolymer form. On a weight basis, the copolymers within the scope of the invention are those containing from 10 to 90 weight percent propylene or butene-1 and preferably from 25 to 75 weight percent propylene or butene-1. The optimum propylene or butene-1 concentrations will, of course, vary depending upon which monomer or monomers are used as the other alpha-monoolefin component.

As indicated above, high molecular weight copolymers are used in the compositions of the present invention. The only practical limitation on molecular weight is that it must be high enough to provide effective mist suppression without being so high as to cause handling difficulties. With regard to the latter, very high molecular weight copolymers have been found to be difficult to dissolve in the base oil of lubricating oil compositions. They are also difficult to filter or pour at low temperatures. The use of very high molecular weight polymers also tends to result in lubricating oil formulations which are relatively unstable. Therefore, the copolymers useful in the present invention are generally limited to those which have an average viscosity average molecular weight of no more than about 10 million. In general, the viscosity average molecular weight of desirable copolymers is usually greater than 100,000 and typically is in the range of 100,000 to 10 million. The average molecular weight of copolymers used in the present invention is preferably in the range of 500,000 to 10 million and is most preferably in the range of 1 to 8 million. In general, the effectiveness of fog suppression increases as the molecular weight of the copolymer additive increases.

The molecular weight of polymers can be determined by any of several methods including light scattering and vapor phase osmometry, gel permeation chromatography (GPC), or the like. Some methods of determining molecular weight provide a weight average molecular weight, while other methods provide a number average molecular weight or a viscosity average molecular weight. For the sake of consistency, the term "average molecular weight" as used in this specification and the appended claims is intended to mean viscosity average molecular weight. Typically, viscosity average molecular weight can be determined by gel permeation chromatography (GPC) conducted at 135°C using a narrow molecular weight range polystyrene bead calibration standard and ortho-dichlorobenzene as the solvent. Basically, GPC uses the size of the polymer molecules, defined by the hydrodynamic radius, as a means of determining molecular weight. The procedure involves passing a solution of the polymer through a bed of cross-linked polymer. Smaller molecules can diffuse into the pores of the cross-linked polymer bed, so that their passage through the bed is delayed compared to larger molecules, which pass through the pores and remain in the solvent phase. For more information on GPC, see WW Yau et al., Modern Size-Exclusion Liquid Chromatography, Wiley-Interscience (1979) and Waters Associates Liquid Chromatography Solvent Manual, Waters Associates (Millipore Corp.) (1983).

The amount of copolymer additive that is necessarily added to the chain saw lubricating oil compositions of this invention to obtain the desired mist suppression result (expressed as a weight percent, i.e., parts weight of copolymer/100 parts weight of fully formulated lubricating oil composition including the copolymer) varies depending on the physical properties and formulation of the lubricating oil composition. In some formulations, the desired result can be achieved by adding 0.0001 weight percent or less of the copolymer to the lubricating oil composition. On the other hand, as much as 1.0 weight percent or more of copolymer addition may be required to produce the desired result. However, it has been found that the desired result is typically obtained by adding 0.005 to 0.5 weight percent of the copolymer to the chain saw lubricating oil composition. In preferred embodiments, the copolymer is added to the lubricant composition in amounts of about 0.005 to about 0.04 weight percent.

Since the copolymer is a solid at the specified molecular weight, it is usually preferred to dissolve it in a suitable solvent or suspend it in a suitable diluent before use, since it is easier to add it to the lubricating composition in the form of a solution or a slurry. Suitable solvents and diluents include kerosene, naphtha and other petroleum distillates, and inert hydrocarbons such as hexane, heptane, octane, and the like.

The lubricating base oil to which the mist suppressing copolymers are added to form the lubricating oil compositions of the present invention can be a mineral oil or a synthetic hydrocarbon oil of lubricating viscosity, typically having a viscosity of 13.08 m²/second (70 Saybolt Universal Seconds (SUS)) up to 69.6 m²/second (300 Saybolt Universal Seconds (SUS)) at 37.8°C (100°F). While the oil may be paraffinic, naphthenic or a blend based, it is preferred that the base oil be substantially nonpolar and that it be substantially inert. The term "substantially nonpolar" as used in the specification and appended claims is intended to mean that the base oil can contain no more than about 0.5% by weight of oxygen, nitrogen and/or sulfur, and the term "substantially inert" is intended to mean that the material described is inert with respect to chemical or physical change under the conditions in which it is used so that it does not substantially interfere with the preparation, storage or mixing and/or functioning of the compositions, additives, compounds, etc. of this invention in the context of its intended use. For example, small amounts of base oil or a solvent, diluent, etc. may undergo minimal reaction or degradation without preventing the preparation and use of the invention described herein. In other words, such a reaction or degradation, although technically possible, would not be sufficient to prevent one of ordinary skill in the art from making and using the invention for its intended purposes. "Substantially nonpolar" and "substantially inert" as used herein are therefore readily understood and recognized by those of ordinary skill in the art.

The base oils useful in preparing the compositions of the present invention include those conventionally used in single-use lubricating oil formulations.

Representative examples of fluids suitable for use as a base oil include mineral and synthetic oils, e.g. the neutral solvents, paraffin oils, naphthenic oils, etc., the linear and branched alkanes and haloalkanes having 6 to 18 carbon atoms, polyhalo- and perhaloalkanes having up to about 6 carbon atoms, the cycloalkanes having 5 or more carbon atoms, the corresponding alkyl and/or halogen-substituted cycloalkanes, the aryl hydrocarbons, the lower alkylaryl hydrocarbons and the haloaryl hydrocarbons.

Specific examples include Stoddard solvent, hexane, decane, isooctane, undecane, tetradecane, cyclopentane, cyclohexane, isopropylcyclohexane, 1,4-dimethylcyclohexane, cyclooctane, benzene, toluene, xylene, ethylbenzene, tert-butylbenzene, halogenobenzenes, particularly mono- and polychlorobenzenes such as chlorobenzene as such, 3,4-dichlorotoluene, 1,2-difluorotetrachloroethane, dichlorofluoromethane, 1,2-dibromotetrafluoroethane, trichlorofluoromethane, 1-chloropentane and 1,3-dichlorohexane.

The low molecular weight liquid polymers, generally classified as oligomers, are also useful as base oils and include the dimers, tetramers, pentamers, etc. Exemplary of this large class of materials are such liquids as the propylene tetramers, isobutylene dimers, and the like.

Mineral oils are preferred. Suitable mineral lubricating oils vary widely depending on their raw material source, e.g., whether they are paraffinic, naphthenic or mixed paraffinic-naphthenic and the like, as well as their formation, e.g., distillation range, straight run or cracked, hydrorefined, solvent extracted and the like.

More specifically, the natural lubricating oil base stocks that can be used in the compositions of the present invention can be liquid petroleum oils, straight mineral lubricating oils, solvent treated, acid treated or distillates derived from paraffinic, naphthenic, asphaltic or mixed base stocks, or, if desired, various mixed oils can be used, as well as residues, particularly those from which asphaltic components have been removed. Oils of suitable viscosity derived from coal or shale are also useful as base oils.

Synthetic base oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g. polybutylenes, polypropylenes, propylene/isobutylene copolymers, poly(1-hexenes), poly(1-octenes), poly(1-decenes)), alkylbenzenes (e.g. dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes), polyphenyls (e.g. biphenyls, terphenyls, alkylated polyphenyls) and the essentially non-polar derivatives, analogues and homologues thereof.

Unrefined, refined and rerefined oils can be used as the base oil in accordance with the present invention. Unrefined oils are those that have been obtained directly from a mineral or synthetic source without further purification treatment. For example, a shale oil obtained directly by retorting operations, a petroleum obtained directly by distillation and used without further treatment would be an unrefined oil. Synthetic crude oils obtained from tar sands are another example of unrefined oil. Refined oils are similar to unrefined oils, except that they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques, such as distillation, solvent extraction, hydrotreating, acid or base extraction, filtration and percolation, are known to those skilled in the art. Re-refined oils are obtained by processes similar to those used to obtain refined oils and applied to refined oils that have already been used in service. Such re-refined oils are also known as reclaimed oils or remanufactured oils and are often additionally processed by techniques to remove spent additives and oil degradation products.

The preferred base oils include the linear and branched C6 to C18 alkanes, mineral oil and refined petroleum oils.

The chainsaw lubricating oil compositions of the present invention may contain only the base oil and the mist suppressing copolymer additive and may be formulated simply by mixing the base oil and the mist suppressing additive together. However, it is contemplated that other additives may be combined with the base oil and the mist suppressing copolymer additives to provide additional properties that make the present compositions more desirable. Other conventional additives that may be included in the chainsaw compositions of the present invention include, for example, rust inhibitors, antioxidants, pour point depressants, antiwear additives, antifoam additives, and the like.

Rust inhibitors that can be added to the chainsaw lubricating compositions according to the invention include, for example, basic nitrogen compounds such as dicarboxylic acid amides and fatty acid amides, imidazolines and phosphoric acid derivatives such as dialkyl or diaryl dithiophosphate salts. Other suitable rust inhibitors include alkylphenols, sulfurized alkylphenols, alkyl salicylates, alkenyl succinic anhydrides and other oil-soluble mono- and dicarboxylic acids, mixtures derived from the reaction product of fatty acids (e.g. C8 to C22), boric acid and hydroxyamines, e.g. diethanolamine containing borated fatty amides and borate hydroxyamine esters, borate esters of hydroxyalkylamines such as diethanolamine (see American Patent US-A-3,642,652), arylsulfonamidecarboxylic acids, their amine salts and mixtures of the same with borated esters of diethanolamine (see American Patent US-A-4,297,236) and divalent metal or amine salts of sulfonic acid, polybasic acids (e.g. tall oil fatty acids) and alkanolamides (see American patent US-A- 4 395 286).

Oxidation inhibitors or antioxidants reduce the tendency of mineral oils to deteriorate with use, the deterioration being evident from oxidation products such as sludge and gummy deposits on the chain saw joints, links or other metal surfaces being lubricated. Such oxidation inhibitors include alkaline earth metal salts of alkylphenol thioesters having preferably C₅ to C₁₂ alkyl side chains, e.g. Calcium nonylphenol sulfide and barium octylphenyl sulfide, aromatic amines such as dioctylphenylamine and phenyl-α-naphthylamine, phosphosulfurized or sulfurized hydrocarbons and hindered phenols such as butylated hydroxytoluene.

Pour point depressants, otherwise known as lubricating oil flow improvers, lower the temperature at which the fluid flows and can be poured. Such additives are widely known. Typical of such additives that usefully optimize the low temperature flowability of a functional fluid are C8 to C18 dialkyl fumarate/vinyl acetate copolymers, polymethacrylates, alkylated polystyrene and paraffin naphthalene.

Anti-wear additives that are useful in certain applications to prevent seizure of moving parts of the chain saw include, for example, metal dithiocarbamates, molybdenum disulfide, chlorinated hydrocarbons, organic phosphates such as tricresyl phosphate, and zinc salts of dialkyl and diaryl dithiophosphoric acids. Such zinc salts also function as oxidation inhibitors and to prevent copper corrosion.

Friction modifiers are used to impart appropriate friction properties to lubricating oil compositions such as chainsaw oils.

Representative examples of suitable friction modifiers are described in U.S. Patent No. 3,933,659 which describes fatty acid esters and amides, U.S. Patent No. 4,176,074 which describes molybdenum complexes of polyisobutenyl succinic anhydride aminoalkanols, U.S. Patent No. 4,105,571 which describes glycerol esters of dimerized fatty acids, U.S. Patent No. 3,779,928 which describes alkanephosphoric acid salts, U.S. Patent No. 3,778,375 which describes reaction products of phosphorate with an oleamide, U.S. Patent No. 3,852,205 which describes S- Carboxyalkylene hydrocarbyl succinimide, S-carboxyalkylene hydrocarbyl succinamide acid and mixtures thereof, American Patent US-A-3 879 306 which describes N-(hydroxyalkylene)alkenyl succinamide acids or succinimides, American Patent US-A-3 932 290 which describes reaction products of di(lower alkyl)phosphites and epoxides, and American Patent US-A-4 028 258 which describes alkylene oxide adducts of phosphosulfurized N-(hydroxyalkyl)alkenyl succinimides. The most preferred friction modifiers are succinate esters or metal salts thereof of hydrocarbon substituted succinic acids or anhydrides and thiobis-alkanols, such as those described in U.S. Patent No. 4,344,853.

Foam control can be provided by a polysiloxane type antifoam additive such as silicone oil and polydimethylsiloxane.

Some of these numerous additives can provide a variety of effects, e.g. a dispersant/oxidation inhibitor. This approach is well known and does not need to be explained in detail here.

Compositions, when containing these conventional additives, are typically blended into the base oil in amounts effective to provide the function normally associated with them. Representative effective amounts of the above classes of additives in the chainsaw lubricating oil formulations of the present invention are summarized below:

The chain saw lubricating oil compositions can be prepared simply by blending the various components together. Typically, all of the minor components are added to the base oil; they can be added neat or as concentrates in oil and/or as solvent solutions, the oil and/or solvent being compatible with the base oil. The components can be blended all at the same time or, if desired, one or more of the components can be blended separately and the blends then blended with the remaining components to form the final compositions.

The following examples are given as specific illustrations of the invention as claimed. It is to be understood, however, that the invention is not limited to the specific details given in the examples. All parts and percentages in the examples and in the remainder of the specification are by weight unless otherwise indicated.

example 1

A series of binary polymer/solvent mixtures (Formulations 1 to 7) were prepared by using a heptane carrier solvent and a butene-1/dodecene-1 anti-fog copolymer (10% active copolymer ingredient dissolved in kerosene). The butene-1/dodecene-1 copolymer was a commercially available product from Baker Performance Chemicals, Houston, Texas, under the trade name Flo 1003 Pipelinebooster. The copolymer was a white, opaque, viscous liquid having a flash point of 51.7ºC (125ºF), a boiling point of 176.7ºC (350ºF), and a specific gravity of 0.79. The viscosity average molecular weight of the copolymer was approximately 4.4 million. The compositions of Formulations 1 through 7 are summarized in Table 1.

Example 2C

The procedure of Example 1 was followed except that the butene-1/dodecene-1 copolymer fog suppressor was replaced with a commercial polyisobutylene polymer fog suppressor. The polyisobutylene polymer was a commercial product of Exxon Chemical Co., Houston, Texas and was available under the trade name Vistanex MM L-140. The polymer had a viscosity average molecular weight of 2.11 million and is believed to be the highest molecular weight polyisobutylene commercially produced in the United States. The polymer was added neat to the heptane carrier solvent to form Formulations 8C through 13C, the compositions of which are summarized in Table 1.

Example 3C

A comparative formulation 14C was prepared which contained only heptane but no fog suppressing additive.

The compositions of formulations 1 to 7 and 8C to 14C are summarized in the following Table 1: Table 1

¹ includes hexane carrier solvent and kerosene (diluent for the anti-mist additive)

The anti-mist properties that can be imparted to a liquid by the addition of a high molecular weight polymer can be observed using various techniques. A simple technique that provides a qualitative measurement of the anti-mist properties is the microatomization spray technique. This method uses a microatomization spray bottle equipped with a pump to pressurize the contents of the bottle. A suitable bottle for use in this method, known as A spray bottle known as an Airspray can be purchased from Consolidated Plastics Co., Twinsburg, Ohio. Such microatomizing spray bottles are typically equipped with a series of interchangeable outlet tips or nozzles that control the pattern of the material sprayed. The Airspray spray bottle, for example, is equipped with three standard nozzles designed to expel an unthickened material (such as water) from the bottle in a pattern of heavy mist, fine mist, or jet, respectively.

To demonstrate the effectiveness of the copolymeric mist suppressing additive of the present invention, a sample of Formulation 14C (heptane control) was filled into the sprayer equipped with the standard nozzle designed to expel the contents of the bottle as a heavy mist. The sprayer was then pumped to pressurize the heptane sample to a recorded level sufficient to expel the heptane sample from the bottle as a heavy mist.

The above procedure was then repeated (washing out the sprayer after each use) using samples of Formulations 1 to 7 and 8C to 13C. Each sample tested used the same nozzle that had been used to spray the control sample (Formulation 14C), with the spray pattern usually being compared to the spray pattern of the control sample. It was observed that samples of Formulations 1, 2, 8C to 11c and 14C were expelled from the bottle as a heavy mist, while samples of Formulations 3 to 5, 12C and 13C were expelled as a jet. Formulation 6 resulted in only a very light and cessant flow, while Formulation 7 did not flow from the bottle at all.

The results of the fine atomization spray technology investigations are given in Table 2. Table 2

Table 2 illustrates that the butene-1/dodecene-1 copolymer was effective at suppressing mist formation and converting the liquid ejected from the spray bottle from a mist to a jet at a concentration level of at least as low as 0.03 wt.%. In comparison, the commercially available polyisobutylene additive was not effective at suppressing mist formation until it was added to the heptane carrier liquid at a concentration level of 0.23 wt.%. The use of butene-1/dodecene-1 copolymer as a mist suppressing additive was therefore 7 times more effective than the use of the polyisobutylene additive based on the results of the fine atomization spray test procedure.

An alternative method for evaluating and predicting the anti-fog properties imparted by polymeric fog suppression additives is to measure the extensional viscosity of a solution of the various additives. However, unlike shear viscosity, extensional viscosity is difficult to measure because a liquid cannot be grabbed and pulled at a constant rate. A method for measuring the extensional viscosity of polymeric solutions is given in Exxon Research and Engineering Company's Description of Analytical Method (AM-S) 89-006 (December 1990). This method is used to determine the tear height (h) of a so-called "tubeless siphon" of a dilute polymer solution, as well as the "specific tack" (h/c) of the polymer, where h is a height measured in centimeters and c is the concentration of the polymer in mass percent, in a NORPAR 15 solution (a liquid C₁₅ paraffin). The height (h) in centimeters is defined as the height to which a thin nonwoven strand of polymer solution can be pulled (without breaking) from a container containing the polymer solution by contacting a 3.8 cm long x 20 gauge syringe (flat tip) needle (0.023 inner diameter) (connected to a vacuum pump) with the surfaces of the solution while maintaining a partial vacuum (about -40 KPa) above the polymer solution (at a temperature of about 25 ºC) and moving the needle relative to the surface of the polymer solution at 5 mm/second (± 1 mm/second) (e.g. by lowering the container while keeping the needle point fixed, or by raising the needle above the polymer solution surface in the container) to draw up the polymer solution. A measurement is made of the distance separating the surface of the solution in the container and the needle tip when the siphon ruptures, and this distance, in centimeters, is h. The higher the value of h, i.e. the longer the tubeless siphon liquid column at the break point, the greater the thread-pulling ability of the liquid.

The specific tack (h/c) of the polymer in solution is indicative of the anti-fogging properties of the polymer, i.e. the greater the specific tack, the better anti-fogging properties of the liquids in which the polymer is dissolved can be expected. The vacuum used should be sufficient to maintain an essentially constant rate of liquid flow through the needle. Generally a vacuum of about -40 KPa is used. For more information see K.K. Chao and M.C. Williams, J. Rheology, 27 (5) 451-474 (1983).

Example 4

A series of sample formulations (Formulations 15 to 18, 19C and 20C) were prepared by dissolving varying concentrations of either butene-1/dodecene-1 copolymer (10 wt.% active ingredient in kerosene) or high molecular weight polyisobutylene (5 wt.% active ingredient in paraffin oil) in NORPAR 15 carrier oil. Each of the samples was tested for specific tack according to Exxon Research and Engineering Company analytical method (AM-S) 89-006 (December 1990) as indicated above. The composition and specific tack of each formulation is summarized in Table 3. Table 3

¹ Carrier oil = C₁₅-paraffin oil (NORPAR 15).

² Flo 1003 pipeline booster from example 1.

³ Polyisobutylene from Example 2C (Vistanex MM L-140).

&sup4; Polymer solution which acted as a semi-solid at the needle tip and did not penetrate into the needle.

Table 3 illustrates that the butene-1/dodecene-1 copolymer is an effective tackifier for a mineral oil vehicle, even at very low concentration levels. Therefore, the use of as little as 15.6 ppm of butene-1/dodecene-1 copolymer resulted in a polymer solution break height comparable to that observed when 10,000 ppm of high molecular weight polyisobutylene was used as the tackifying resin.

Example 5

A series of chain saw lubricating oil formulations (Formulations 21 to 26) were prepared by blending varying amounts of the butene-1/dodecene-1 copolymer mist suppression additive of Example 1 with a lubricating oil feedstock, an antioxidant additive, and a rust inhibitor additive. Several comparative formulations were prepared to which no mist suppression resin was added (Formulation 27C), or in which the butene-1/dodecene-1 copolymer additive (10 wt.% active ingredient in kerosene) was replaced by either the polyisobutylene polymer (5 wt.% active ingredient in paraffin oil) of Example 2C (Formulations 28C and 29C) or by a commercial solution of a polymeric tackifier believed to be an ethylene/propylene copolymer (5 wt.% active ingredient in petroleum feedstock) having a viscosity average molecular weight of about 250,000 (Formulations 30C and 31C). Comparative Formulation 32C was prepared to comprise only the lubricating oil feedstock without any mist suppression additive, antioxidant additive or rust inhibitor additive.

The room temperature viscosity for each formulation was determined. Each formulation was also tested according to Exxon Research and Engineering Company analytical method (AM-S) 89-006 (December 1990) and the height at break (h) of each formulation was determined.

The compositions of formulations 21 to 26 and 27C to 32C and the test results are summarized in Tables 4, 5 and 6 below: Table 4

¹ including kerosene thinner

² butylated hydroxytoluene

³ Half ester of alkenyl succinic acid (PARABAR 302 - a product of Exxon Chemical Company, Bayway, New Jersey).

&sup4; Exxon 105 white paraffin feed (21.7 m²/s 105 Saybolt-second kinematic viscosity) at 40 ºC. Table 5

¹ butylated hydroxytoluene

² Half ester of alkenylsuccinic acid (PARABAR 302

³ Exxon 105 white paraffin feed (21.7 m²/s 105 Saybolt-second kinematic viscosity) at 40 ºC.

The data in Tables 4 to 6 illustrate that chain saw lubricating oil formulations containing as little as 0.025 wt.% butene-1/dodecene-1 copolymer as a mist suppression additive are characterized by a measurable tear height in the test procedure for determining the specific tack of a polymer solution. The data also illustrate that the tear height measured when butene-1/dodecene-1 copolymer is used as a mist suppressor is comparable to the tear height observed for formulations using 5 times as much polyisobutylene or ethylene/propylene copolymer in place of the butene-1/dodecene-1 copolymer. The data also illustrate that formulations not containing a mist suppression additive do not produce a measurable tear height.

While the invention has been described with reference to preferred embodiments thereof, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. It is therefore to be understood that the invention described herein is intended to include such modifications as being within the scope of the appended claims.

Claims (10)

1. A method for suppressing mist formation from a single-use lubricating oil, which comprises: 0.0001 to 0.04 weight percent of a copolymer prepared by copolymerizing at least one α-monoolefin selected from propylene and butene-1 with at least one additional α-monoolefin having 5 to 20 carbon atoms, the copolymer having a viscosity average molecular weight of about 100,000 to 20 million, is mixed with the disposable lubricating oil. 2. The process of claim 1 wherein the copolymer has been prepared by copolymerizing butene-1 with at least one additional α-monoolefin having 6 to 14 carbon atoms. 3. The process of claim 2, wherein the additional monoolefin is selected from the group consisting of hexene-1, octene-1, decene-1, dodecene-1, tetradecene-1 and mixtures thereof. 4. The method of claim 3, wherein the copolymer is mixed with the fluids in a concentration of 0.005 to 0.04 wt.%. 5. The process of claim 1 wherein the copolymer comprises 10 to 90 mole percent of units derived from C3 to C4 monoolefin and 90 to 10 mole percent of units derived from C5 to C20 monoolefin. 6. The process of claim 5 wherein the copolymer comprises from 25 to 75 mole percent of units derived from C3 or C4 monoolefin and from 75 to 25 mole percent of units derived from C5 to C20 monoolefin. 7. The process of claim 1 wherein the copolymer comprises 10 to 90 mole percent of units derived from butene-1 and 90 to 10 mole percent of units derived from C6 to C14 monoolefin. 8. A process according to claim 7, wherein the units derived from butene-1 constitute 25 to 75 mole percent of the copolymer. 9. A process according to any one of claims 1 to 8, wherein the copolymer has a viscosity average molecular weight of 500,000 to 10 million. 10. A method according to any one of claims 1 to 8, wherein the single-use lubricating oil and the copolymer are further mixed with an effective amount of at least one additional additive selected from the group consisting of (i) rust inhibitors, (ii) antioxidants, (iii) pour point depressants and (iv) antiwear agents.