NO312910B1 - Use of a high molecular weight copolymer as an additive to a nausea lubricating oil for suppressing mist formation - 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

The present invention relates to the use of a copolymer with a high molecular weight for the suppression of haze from oily functional fluids suitable for single-use applications such as, for example, rock drilling oils, agricultural spray oils, chain saw oils, ammonium nitrate fuel oil for explosives, lubricants for sheet metal drawing and the like. More particularly, the invention relates to the use as an additive to oily, disposable functional fluids, such as chainsaw lubricating oil core compositions, of a haze-suppressing amount of a high molecular weight copolymer prepared from alpha-monoolefins having from 3 to about 20 carbon atoms.

Oil-containing compositions used as lubricants for chain saws generally comprise a lubricating oil component and an adhesion component which is intended to prevent the compositions from misting or splashing from the chain end during use. Known lubricant compositions for chain saws, as described, for example, in US patent 4,740,324, include such adhesion components as polyethylene glycol or polyacrylamide, each having a molecular weight of 1 million or more, or rosin-containing resins such as balsam resin obtained from turpentine balsam, root resin obtained by solvent extraction from rhizomes, and tall resin obtained from fractional distillation of tall oil.

The use of an anti-fog additive in various other lubricating oil compositions has also been described. For example, US Patents 3,929,652 and 4,210,544 relate to dual purpose cutting oils that serve as heavy duty cutting oils and machine lubricants and which comprise a base oil, a high pressure agent, a copper corrosion inhibitor and preferably a copolymer of ethylene and propylene as an anti-dist additive. Particularly preferred antidiscopolymer additives are indicated to have a molecular weight varying from about 70,000 to about 100,000 and a propylene content from about 35 to about 50%.

GB Patent 1,525,599 discloses a mineral oil composition for metalworking which contains a major amount of an oil of lubricating viscosity, and a minor amount, sufficient to inhibit the composition from fogging in use, of at least one oil-soluble ethylene copolymer which has a viscosity average molecular weight in the range of 130,000-250,000. The ethylene copolymer is derived from the copolymerization of ethylene and a heavier olefin selected from terminally unsaturated, straight-chain monoolefins containing 3-12 carbon atoms, alpha-phenyl-1-alkenes containing 9 or 10 carbon atoms, 2-norbornene, terminally unsaturated, non- conjugated diolefins containing 5-8 carbon atoms, dicyclopentadiene, 5-methylene-2-norbomene, and mixtures thereof. The heavier olefin is preferably propylene and the molar ratio of ethylene to the heavier olefin in the copolymer is in the range from 1:3 to 3:1.

US patent 3,919,098 metalworking sarrin deposits that have improved low-fog properties. The described compositions comprise a major amount of a hydrocarbon oil and a minor amount of an anti-fog additive selected from polyisobutylene, poly-n-butene and mixtures thereof. The anti-fog additive is stated to have a viscosity average molecular weight of from 0.3 to 10 million.

US patent 3,805,918 disoil lubrication systems that pneumatically distribute fine droplets of an oil composition to areas with various machine elements to be lubricated. The oil compositions described in this patent include a small amount of specified polyolefins to reduce the amount of dispersed mist during the lubrication process. The polyolefins described are C2Cx copolymers of ethylene having a viscosity average molecular weight of over 5,000. The polyolefins contain 40-80 molar percent ethylene and the units defined as Cx are derived from a C3-C12 monoolefin. The preferred polyolefins are ethylene-propylene copolymers.

US patent 4,105,569 relates to yarn finishes, especially of the king oil type, which comprise a viscosity index improving agent such as a polymethacrylate, a polyalkylstyrene, an ethylene-propylene copolymer or a polyisobutylene. The viscosity index improver provides better attachment of the applique to the yarn being treated, less tendency to drip, and less applique "kickback" during rapid winding of the treated game. The Gamapperture formulations also contain a polysiloxane which works in such a way that it reduces the surface tension of the finisher and prevents fogging during rapid winding.

US patent 4,400,281 relates to improving 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 0.01-10% by weight of a polymer having a molecular weight of 1-10 million and comprise either homopolymer of normal C6-C4 alpha-monoolefins or copolymers of two or more normal C4-C20 alpha-monoolefins. Among the copolymers that can be added to the textile lubricant composition are copolymers of butene-1 and at least one C5-C44 alpha-monoolefin such as hexene-1, octene-1, decene-1, dodecene-1 and/or tetradecene-1. The addition of the polymer improves the adhesiveness of the lubricating composition without reducing its lubricity and reduces the tendency of the composition to warp.

US patent 4,173,455 relates to aqueous diesel fuel emulsions containing diesel fuel, a specified emulsifier, an anti-fog agent and water. The anti-fog is added to the fuel emulsion to prevent the emulsion from atomizing on impact when a fuel container ruptures. The anti-mist is believed to cause the fuel emulsion to be ejected from the ruptured fuel container in the form of "sheets" and "strings of globules" that do not provide sufficient surface area for explosive combustion. The antidispersants for use in the diesel fuel emulsion are described as high molecular weight long chain polymers that were developed to improve the flow of oil through pipelines. In the US patent's column 3, lines 32-35, it is stated that the antidispersants used were brand-name mixtures purchased under the trade name CDR or AM-1 (from Continental Oil Company) and that the mixture of the antidispersants was unknown. While the exact identity of the CDR or AM-1 polymer compositions is unknown to the present inventors, it is believed that the compositions comprise homopolymers of octene-1.

US patents 4,384,089 and 4,527,581 relate to the fact that the reduction of frictional losses that normally occur in hydrocarbon-carrying pipelines during the transportation of hydrocarbon liquids can be reduced by adding small amounts of certain copolymers to the hydrocarbon liquids. The copolymers are stated in US patent 4,384,089 to include copolymers of two or more alpha-monoolefins having 3-20 carbon atoms, and in US patent 4,527,581 to include copolymers of butene-1 and another alpha-monoolefin having 5-20 carbon atoms. None of these patents suggest the use of the copolymers as anything other than agents for reducing the friction in pipelines against hydrocarbon oils.

It is an object of the present invention to impart elasticity or resilience to an oily functional fluid which is affected by shear, centrifugal or gravity-induced forces which tend to cause the fluid to separate either from itself or from the surfaces on which it has been applied.

Another object is to increase the cohesive and adhesive strength of an oily functional fluid by adding thereto an adhesion additive in the form of a high molecular weight alpha-olefin copolymer.

A further object is to provide an oily functional fluid which is suitable for single-use applications, such as for the lubrication of chainsaw blades and joints, where the functional fluid is prevented from misting or splashing by using a copolymer prepared from at least two alpha-monoolefins containing from 3 to 20 carbon atoms and with a viscosity average molecular weight from 500,000 to 10 million, as an additive to said fluid.

According to the present invention, there is thus provided the use of 0.0001-0.04% by weight of a copolymer prepared by the copolymerization of at least one alpha-monoolefin selected from propylene and butene-1 with at least one further alpha-monoolefin having 5-20 carbon atoms, where the copolymer has a viscosity average molecular weight of from 100,000 to 20 million, as an additive to a single-use lubricating oil for mist suppression.

Preferred and advantageous features of this application appear from the accompanying claims 2-10.

In the present context, a larger amount of a base oil component and a smaller, haze-suppressing amount of a copolymer component derived from at least one monoolefin selected from propylene and butene-1 and at least one additional alpha-monoolefin having 5-20 carbon atoms are used. In preferred embodiments of the invention, a haze-suppressing copolymer is used which is produced by copolymerization of butene-1 with at least one other alpha-monoolefin having 5-20 carbon atoms. The alpha-monoolefins which are copolymerized with butene-1 are preferably those having 6-14 carbon atoms, with hexene-1, octene-1, decene-1, dodecene-1 and tetradecene-1 being the most preferred comonomers. The copolymeric mist suppressant to be mixed with the base oil component preferably has a viscosity average molecular weight of over 100,000, for example from 100,000 to about 20 million and will generally comprise from about 10 to 90 mol-% C3 or C4 hydrocarbon units and from about 90 to 100 mol% units derived from other C5-C20 alpha-monoolefins.

The copolymer agent is added to the oily functional fluid at a concentration effective to provide the desired mist suppression. In preferred embodiments of the invention where propylene or butene-1 is copolymerized with a C8-C4 alpha-monoolefin, the haze suppressant copolymer contains 25-75 mol% C3- or C4-derived hydrocarbon units, is added to the functional fluid composition at a concentration from about 0.0001% by weight (1 ppm) to about 0.04% by weight (400 ppm), and has a viscosity average molecular weight in the range from about 500,000 to about 10 million. Among the more preferred copolymers for use in the present invention are those prepared from butene-1 and one or more of hexene-1, octene-1, decene-1, dodecene-1 and tetradecene-1.

Although the invention is applicable to the suppression of misting, also known as spraying, fogging or the like, from a number of different oily functional fluids, the description below for purposes of illustration has been limited to a mention of functional fluids that are particularly adapted for single-use lubrication applications , such as, for example, lubrication of chainsaw blades.

Surprisingly low levels of mist or spray occur during operation of a chain saw when the chain saw operating fluid composition comprises a major amount of an oil of lubricating viscosity and a minor amount of a high molecular weight copolymer of propylene or butene-1 and at least one alpha-monoolefin which has from 5 to about 20 carbon atoms. The high molecular weight copolymer will typically be added to the chainsaw lubricating fluid at a concentration of about 0.005 to about 0.04% by weight to achieve the desired low levels of mist formation.

In general, very favorable haze suppression has been observed when the copolymer additives are prepared from alpha-monoolefins having from 4 to about 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 present invention because they are readily polymerizable by well-known liquid state polymerization techniques.

Examples of two monomer component systems are propene-1-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-l-dodecene-1, etc. Preferred specific monomeric systems are propene-dodecene-1, butene-1 - dodecene-1, butene-1-decene-1 and hexene-1-dodecene-1.

The process for copolymerization of the monomers does not form part of the invention. In general, any of the numerous well-known methods for polymerizing alpha-monoolefins can be used. A particular method is the Ziegler process which uses catalyst systems comprising combinations of a compound of a metal in groups IV-B, V-B, VI-B or Vm of the periodic table, found on pages 392-393 of the Handbook of Chemistry and Physics, 37th ed. with an organo-metallic compound of a rare earth metal from groups I-A, E-A, ni-B in the periodic table. Particularly suitable catalyst systems are those comprising titanium halides and organoaluminum compounds. A typical polymerization procedure is to contact 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 and in a nitrogen atmosphere. Further details of the Ziegler process are set forth in US Patent 3,692,676.

The total C3 or C4 hydrocarbon concentration in the used copolymers of the haze suppressing additives preferably varies from about 90 mol% to about 10 mol%. The factor which limits the upper concentration of propylene or butene-1 in said copolymers is solubility. When the propylene or butene-1 concentration in the copolymers increases, the crystallinity increases and the solubility of the copolymers in hydrocarbons decreases. Decreasing solubility has a detrimental effect on the lubricating composition. The solubility limits for copolymers will naturally vary with different copolymer systems. In general, the practical upper limit for propylene or butene-1 content for useful copolymers is about 90 mol%. Copolymer compositions that have C3 or C4 concentrations of more than about 90 mol% have relatively poor mist-suppressing properties. On the other hand, the economic advantage of using the cheaper propylene or butene-1 in the preparation of the copolymer compositions is lost if the C3 or C4 hydrocarbon incorporation in the polymer falls below about 10 mol%. In preferred embodiments of the invention, the total C3 or C4 hydrocarbon concentration in the copolymer additive is from about 25 to 75 mol%, and the total concentration of alpha-monoolefin with 5-20 carbon atoms is from about 75 to 25 mol%. Those skilled in the art will appreciate that small amounts of polypropylene or butene-1 may be incorporated into the copolymer composition as a homopolymer and that the above C3 or C4 hydrocarbon concentrations 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 which is present in copolymer form. On a weight basis, copolymers used according to the present invention are those having from about 10 to 90% by weight propylene or butene-1, and preferably from about 25 to 75% by weight propylene or butene-1. The optimum propylene or butene-1 concentrations will of course vary depending on which monomer or monomers are used as the second alpha-monoolefin component.

As mentioned above, high molecular weight copolymers are used in the present application. 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. In this latter respect, it has been found that very high molecular weight copolymers are difficult to dissolve in the base oil of the 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 that are relatively unstable. Accordingly, the copolymers useful in the present invention are generally limited to those having a viscosity average molecular weight of no more than about 10 million. In general, the viscosity average molecular weight of desired copolymers is usually above 100,000 and is typically in the range from about 100,000 to about 10 million. The average molecular weight of copolymers used in the present invention is preferably in the range from about 500,000 to 10 million and most preferably in the range from about 1 to 8 million. In general, haze suppression efficiency will increase as the molecular weight of the copolymer additive increases.

The molecular weight of polymers can be determined by any one of numerous methods including light scattering and vapor phase osmometry, gel permeation chromatography (GPC) or the like. Some methods for determining molecular weight give a weight-average molecular weight, while others give a number-average molecular weight or viscosity-average molecular weight. For uniformity, the term "average molecular weight" in the present context shall mean the viscosity average molecular weight. The viscosity average molecular weight can typically be determined by gel permeation chromatography (GPC) performed at 135°C using a narrow molecular weight range polystyrene bead as a calibration standard and ortho-dichlorobenzene as a solvent. Mainly, GPC uses the size of the polymer molecules, which is defined by the hydrodynamic radius, as a means of determining the molecular weight. The technique involves passing a solution of the polymer through a layer of cross-linked polymer. Smaller molecules can diffuse into the pores of the cross-linked polymer layer so that their passage through the layer is delayed compared to larger molecules that pass past the pores and continue into the solvent phase. For more information regarding GPC, reference should be made to W. W. Yau et al, Modem 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 must be added to the chainsaw lubricating oil compositions to give the desired mist suppressing result (expressed as % by weight, ie parts by weight copolymer per 100 parts by weight of the fully formulated lubricating oil base composition including the copolymer) will vary depending on the physical properties and formulation of the lubricating oil composition. With some formulations, the desired result can be achieved by adding 0.0001% by weight or less of the copolymer to the lubricant composition. On the other hand, some lubricant compositions may require as much as 1.0% or more by weight of copolymer addition to produce the desired result. However, it has been found that the desired result is typically achieved by adding from about 0.005 to about 0.5% by weight of the copolymer to the chain saw chainsaw core composition. In preferred embodiments, the copolymer is added to the lubricating composition in amounts from about 0.005 to about 0.04% by weight.

Since the copolymer is a solid at the indicated molecular weight, it is usually preferred to dissolve it in a suitable solvent or suspend it in a suitable diluent before use because it is easier to add 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 or the like.

The lubricating base oil to which the mist suppressing copolymers are added to form the lubricating oil compositions may be a mineral oil or a synthetic hydrocarbon oil of lubricating viscosity, typically having a viscosity of from 13.08 m<2>/s (70) to 69.6 m<2>/ s (300 Saybolt Universal Seconds (SUS)) at 37.8°C (100°F). While the oil may be paraffinic, naphthenic, or mixed base, it is preferred that the base oil be substantially non-polar and that it be substantially inert. As used in the present context, the term "essentially non-polar" means that the base oil can contain no more than about 0.5% by weight of oxygen, nitrogen and/or sulphur; and by the term "essentially inert" it is meant that the material described is inert to chemical or physical change under the conditions under which it is used so that it does not materially interfere in a harmful way in the manufacture, storage, mixing and/or effect of the compositions, the additives, compounds, etc., of the present 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 hindering the application of the invention as described herein. In other words, such a reaction or breakdown, even if it can be demonstrated in a purely technical manner, would not be sufficient to prevent a person skilled in the art from carrying out and using the invention for its intended purpose. The terms "substantially non-polar" and "substantially inert" used herein will thus be easily understood by experts in the field.

The base oils which are suitable for use in the manufacture of the compositions used include those which are conventionally used in single-use lubricating oil formulations.

Representative examples of liquids suitable for use as a base oil include mineral and synthetic oils, e.g., the solvent neutral, liquid paraffins, naphthenic oils, etc., the linear and branched alkanes and haloalkanes of 6-18 carbon atoms, polyhalo and perhaloalkanes of up to 6 carbon atoms, the cycloalkanes with 5 carbon atoms or more, 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, halozenes especially mono- and polychlorobenzenes such as chlorobenzene per se and 3,4-dichlorotoluene, 1,2-difluorotetrachloroethane, dichlorofluoromethane, 1,2-dibromotetrafluoroethane, trichlorofluoromethane, 1-chloropentane and 1,3-dichlorohexane.

Also useful as base oils are the low molecular weight liquid polymers generally classified as oligomers, which include dimers, tetramers, pentamers, etc. Illustrative 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 greatly with respect to their raw material source, eg whether they are paraffinic, naphthenic, mixed paraffinic-naphthenic, and the like; as well as with regard to their formation, e.g. destination area, directly distilled or cracked, hydrofined, solvent extracted and the like.

The natural lubricating oil raw materials that can be used in the compositions used can more particularly be liquid petroleum oils, pure mineral lubricating oil, solvent-treated, acid-treated or distillates derived from paraffinic, naphthenic, asphaltic or mixed raw materials; or, if desired, various mixed oils may be used as well as residues, especially those from which asphaltic constituents have been removed. Oils of suitable viscosity derived from coal or shale are also useful base oils.

Synthetic base oils include hydrocarbon oils, such as polymerized and inter-polymerized olefins (eg, polybutylenes, polypropylenes, propylene-isobutylene copolymers, poly(l-hexenes), poly(l-octenes), poly(l-decenes)); alkylbenzenes (eg dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes); polyphenyls (eg biphenyls, terphenyls, alkylated polyphenyls); and the substantially non-polar derivatives, analogs and homologues thereof.

Unrefined, refined and re-refined oils can be used as base oil according to the present invention. Unrefined oils are those directly obtained from a mineral or synthetic source without further purification treatment. A shale oil obtained directly from retort processing operations, a petroleum oil obtained directly from distillation and used without further processing would for example be an unrefined oil. "Syncrude" obtained from tar sands is another example of unrefined oil. Refined oils are similar to unrefined oils except that they have been further processed 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 methods such as those used for obtaining refined oils used on refined oils that have already been used. Such re-refined oils are also known as recovered or reprocessed oils and are often further processed by techniques to remove used additives and oil degradation products.

The preferred base oils include the linear and branched C 1 -C 6 alkanes, mineral oil and refined petroleum oils.

Said chainsaw lubricating oil compositions can comprise only the base oil and the mist-suppressing copolymer additive and can be formulated by simple mixing of the base oil and the mist-suppressing additive. However, it is relevant that other additives can be combined with the base oil and the haze-suppressing copolymer additives to obtain additional properties that promote the desirability of the present compositions. Other conventional additives which can be included in the present chain saw compositions include, for example, rust inhibitors, antioxidants, hardening point depressants, anti-wear additives, anti-foam additives and the like.

Rust inhibitors that can be added to said chainsaw butter compositions include, for example, basic nitrogen compounds such as dicarboxylic acid amides and fatty acid amides; imidazolines; and phosphoric acid derivatives, such as dialkyl or diaryldithiophosphate salts. Still 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. Cg-C22X boric acid and hydroxyamines, e.g. diethanolamine containing boronated fatty amines and hydroxyamine borates; borates of hydroxyalkylamines such as diethanolamine (cf. US patent 3,642,652); arylsulfonamide carboxylic acids, their amine salts and mixtures of these with borate-treated esters of diethanolamine (cf. US patent 4,297,236) and divalent metal or amine salts of sulfonic acid, polybasic acids (e.g. tall oil fatty acids) and alkanolamides (cf. US patent 4,395,286).

Oxidation inhibitors or antioxidants reduce the tendency of mineral oils to deteriorate with use and this deterioration can show itself through oxidation products such as sludge and rubber-like deposits on the chainsaw joints, - the bar or other metal surfaces that are lubricated. Such oxidation inhibitors include alkaline earth metal salts of alkylphenol thioesters preferably having C5-C42 alkyl side chains, eg calcium nonylphenol sulfide and barium octylphenyl sulfide; aromatic amines, eg dioctylphenylamine and phenylalpha-naphthylamine; phosphosulphurised or desulphurised hydrocarbons; and hindered phenols such as butylated hydroxytoluene.

Pouring point depressants, otherwise known as lubricating oil flow improvers, lower the temperature at which the fluid will flow or can be poured. Such additives are well known. Typical of the additives that usefully optimize the low-temperature fluidity of a functional fluid are Cg-Cjg dialkyl fumarate-vinyl acetate copolymers, polymethacrylates, alkylated polystyrene, and wax naphthalene.

Anti-wear additives which may be useful in certain applications to prevent rubbing of moving parts in the chain saw, including, for example, metal dithiocarbamates; molybdenum disulfide; chlorinated hydrocarbons; organic phosphates such as tricresyl phosphate, and zinc salts of dialkyl and diaryldithiophosphoric acids. Such zinc salts also act as oxidation inhibitors and prevent copper corrosion.

Friction modifiers serve to impart the proper frictional properties to lubricating oil compositions such as chain saw oils.

Representative examples of suitable friction modifiers are found in US patent 3,933,659 which describes fatty acid esters and amides; US Patent 4,176,074 which describes molybdenum complexes of butenylsuccinic anhydride-amino alcohols; US Patent 4,105,571 which describes glycerol esters of dimerized fatty acids; US Patent 3,779,928 which describes alkane phosphoric acid salts; US Patent 3,788,375 which describes reaction products of a phosphate with an oleamide; US Patent 3,852,205 which discloses S-carboxyalkylene hydrocarbyl succinimide, S-carboxyalkylene hydrocarbyl succinamic acid and mixtures thereof; US Patent 3,879,306 which describes N-(hydroxyalkylene)alkenylsuccinamic acids or -succinimides; US Patent 3,932,290 which describes reaction products of di-(lower alkyl)phosphites and epoxides; and US Patent 4,028,258 which describes the alkylene oxide adduct of phosphorus sulfurized N-(hydroxyalkyl)alkenylsuccinimides. The most preferred friction modifying agents are succinate esters, or metal salts thereof, of hydrocarbyl-substituted succinic acids or anhydrides and thiobisalkanols as described in US patent 4,344,853.

Foam control can be achieved with an antifoam additive of the polysiloxane type, for example silicone oil and polydimethylsiloxane.

Some of these numerous additives can provide a plurality of effects, for example a dispersant-oxidation inhibitor. This is well known and should not need to be discussed further in the present context. Compositions containing these conventional additives are typically incorporated into the base oil in amounts effective to provide the function with which they are normally associated. Representative effective amounts of the above-mentioned classes of additives in the present chainsaw lubricating oil formulations can be summarized as follows:

The chainsaw lubricating oil compositions can be prepared by simple mixing of the various components. All the subordinate components will typically be added to the base oil; they can be added as they are, or as concentrates in oil and/or solvent solutions, where the oil and/or solvent is compatible with the base oil. The components may all be mixed simultaneously, or, if desired, one or more of the components may be mixed separately and the mixtures then further mixed with the remaining components to form the final compositions.

The following examples are given as specific illustrations of the present invention. All parts and percentages in the examples and in the subsequent parts are calculated by weight unless otherwise specified.

EXAMPLE 1

A series of binary polymer/solvent blends (formulations 1-7) were prepared by mixing a heptane carrier solvent and a haze-suppressing butene-1-dodecene-1 copolymer (10% copolymer as active ingredient dissolved in kerosene). The butene-1-dodecene-1 copolymer was a commercial product available from Baker Performance Chemicals, Houston, Texas, under the trade name Flo<®> 1003 piping aid. The copolymer is a white, opaque, viscous liquid with a flash point of 51.7°C, a boiling point of 176.7°C and a specific gravity of 0.79. The copolymer's viscosity average molecular weight is approximately 4.4 million. The composition for formulations 1-7 is summarized in table 1.

EXAMPLE 2C

The procedure in Example 1 was followed with the exception that the haze suppressant butene-1-dodecene-1 copolymer was replaced with a commercial polyisobutylene polymer as haze suppressant. The polyisobutylene polymer was a commercial product of Exxon Chemical Co., Houston, Texas, and is 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 produced commercially in the United States. The polymer was added in unmixed form to the heptane carrier solvent to form formulations 8C-13C, whose composition is summarized in Table 1.

EXAMPLE 3C

Comparative formulation 14C was prepared and comprised only heptane without any haze suppressant additive.

The composition of formulations 1-7 and 8C-14C is summarized in Table 1 as follows:

The anti-dizz properties imparted to a fluid by the addition thereto of a high molecular weight polymer can be observed by means of several techniques. A simple technique that gives a qualitative measure of the anti-fog properties is the nebulizer spray technique. For this procedure, an atomizing spray bottle equipped with a pump is used to pressurize the contents of the bottle. A suitable bottle for use in this procedure, identified as the Airspray™ spray bottle, can be obtained from Consolidated Plastics Co., Twinsburg, Ohio. Such atomizing spray bottles are typically equipped with a series of replaceable outlet nozzles that regulate the spray pattern emitted therefrom. For example, the Airspray™ spray bottle is equipped with three standard nozzles that are designed to eject an unthickened material (such as water) from the bottle in a heavy mist pattern, a fine mist pattern, or a jet pattern, respectively.

To demonstrate the effectiveness of the present mist suppressing copolymer additive, a sample of formulation 14C (heptane control sample) was filled into the spray bottle fitted with a standard nozzle designed to expel the contents of the bottle as a heavy mist. The spray bottle 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 the spray bottle after each use) using samples of formulations 1-7 and 8C-13C. For each sample tested, using the same nozzle that was used to spray the control sample

(formulation 14C), the spray pattern was usually compared to the spray pattern of the control sample. It was observed that the samples of formulations 1, 2, 8C-11C, and 14C were ejected from the bottle as a heavy mist, while the samples of formulations 3-5, 12C and 13C were ejected as a jet. Formulation 6 resulted in only a very weak and uneven flow, while formulation 7 did not flow at all from the bottle.

The results from the assessment with the nebulizer spray technique are given in table 2.

Table 2 shows that butene-1-dodecene-1 copolymer was effective in suppressing mist formation and in converting the fluid ejected from the spray bottle from a mist to a jet stream or jet at a concentration level at least as low as 0 .03% by weight. By comparison, the commercially available polyisobutylene additive was not effective in suppressing haze until it was added to the heptane carrier fluid at a concentration level of 0.23% by weight. Accordingly, based on the results of the pre-dust spray test procedure, the use of butene-1-dodecene-1 copolymer as the haze suppressant additive was more than 7 times as effective as the use of the polyisobutylene additive.

An alternative method for evaluating and predicting the anti-fog properties provided by polymeric anti-fog 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 fluid cannot be gripped and stretched at a constant rate. A method for measuring extensional viscosity of polymer solutions is set forth in Analytical Method Specification (AM-S) 89-006 (December 1990) of Exxon Research and Engineering Company. This procedure is used to determine the breaking height (h) of a so-called "tubeless siphon" of a dilute polymer solution, as well as the "specific adhesion" (h/c) of the polymer, where h is a height measured in cm 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 flowing strand of the polymer solution can be drawn (without breaking) from a container containing the polymer solution by touching the surface of the solution with a 3.8 cm long x 20 gauge syringe ( flat tip) needle (0.584 mm inner diameter) (connected to a vacuum pump), while maintaining a partial vacuum (about -40 kPa) over the polymer solution (at a temperature of about 25°C), and moving the needle relative to the polymer solution surface at 5 mm/second (± 1 mm/sec) (e.g. by lowering the container while keeping the needle tip fixed, or by raising the needle above the surface of the polymer solution in the container (to suck up the polymer solution). The distance separating the surface of the solution in the container and the tip of the needle when the siphon action is broken is measured and this distance, in centimeters, is h. Therefore, the higher the value for h, i.e. the longer the tube-free siphon liquid column is at break, the larger re is the thread-like or string-like nature of the fluid.

The specific adhesion (h/c) to the polymer in solution suggests the polymer's anti-fog properties, i.e. the greater the specific adhesion, the better the anti-fog properties can be expected for the fluids in which the polymer is dissolved. The vacuum used should be sufficient to maintain a substantially constant rate of fluid flow through the needle. A vacuum of about -40 kPa will usually be used. For more information, see K.K.K. Chao and M.C. Williams, J. Rheology, 27 (5) 451-474

(1983).

EXAMPLE 4

A series of trial formulations (formulations 15-18, 19C and 20C) were prepared by dissolving varying concentrations of either butene-1-dodecene-1 copolymer (10 wt% a.i. in kerosene) or high molecular weight polyisobutylene (5 wt% a.i. in paraffinic oil) in NORPAR<®>15 carrier oil. Each of the samples was tested for their specific adhesion according to Analytical Method Specification (AM-S) 89-006 (December 1990) of Exxon Research and Engineering Company, as discussed above. The composition and adhesion of each formulation are listed in Table 3.

Table 3 shows that butene-1-dodecene-1 copolymer is an effective adhesion agent for a mineral oil carrier, even at very low concentration levels. Thus, the use of as little as 15.6 ppm butene-1-dodecene-1 copolymer resulted in a polymer dissolution break height comparable to that observed using 10,000 ppm high molecular weight polyisobutylene as the adhesive resin.

EXAMPLE 5

A series of chainsaw lubricating oil formulations (formulations 21-26) were prepared by mixing different amounts of the butene-1-dodecene-1 copolymer haze suppressant from Example 1 with a lubricating oil base material, an antioxidant additive and an antirust additive. Several comparative formulations were prepared without the addition of any haze-suppressing resin (formulation 27C), or where the butene-l-dodecene-l copolymer additive (10 wt% a.i. in kerosene) was replaced either with the polyisobutylene polymer (5 wt% a.i. in paraffin oil) from example 2C (formulations 28C and 29C) or with a commercial polymer adhesion solution believed to be an ethylene-propylene copolymer (5% by weight a.i. in mineral oil base material) having a viscosity average molecular weight of about 250,000 (formulations 30C and 31C). Comparative Formulation 32C was prepared and comprised only lubricating oil base stock with no mist suppressant additive, no antioxidant additive, and no antirust additive. The room temperature viscosity of each formulation was measured. Each formulation was also tested according to Analytical Method Specification (AM-S) 89-006 (December, 1990) of Exxon Research and Engineering Company, and the fracture height (h) of each formulation was measured.

The composition for formulations 21-26 and 27C-32C and the test results are summarized in Tables 4, 5 and 6 below. The data in Tables 4-6 show that chainsaw lubricating oil formulations containing as little as 0.025% by weight butene-1-dodecene-1 copolymer as haze suppressant additive are characterized by a measurable break height in the test procedure for determining the specific adhesion to a polymer solution. The data also show that when using butene-1-dodecene-1 copolymer as a haze suppressant, the measured break height is comparable to the break height recorded for formulations using five times as much polyisobutylene or ethylene-propylene copolymer instead of the butene-1-dodecene-1 copolymer. Furthermore, the data show that formulations that did not contain any haze-suppressing additive did not produce any measurable break height.

Claims (10)

1. Use of 0.0001-0.04% by weight of a copolymer prepared by the copolymerization of at least one alpha-monoolefin selected from propylene and butene-1 with at least one additional alpha-monoolefin having 5-20 carbon atoms, wherein the copolymer has a viscosity molecular weight from 100,000 to 20 million, as an additive to a single-use lubricating oil for suppressing mist formation. 2. Use according to claim 1, where the copolymer is produced by copolymerization of butene-1 with at least one further alpha-monoolefin having 6-14 carbon atoms. 3. Use according to claim 2, wherein said further monoolefin is selected from the group consisting of hexene-1, octene-1, decene-1, dodecene-1, tetradecene-1 and mixtures thereof. 4. Use according to claim 3, where said copolymer is mixed with said fluids at a concentration of from 0.005 to 0.04% by weight. 5. Use according to claim 1, wherein said copolymer includes 10-90 mol-% C3-C4 monoolefin-derived units and 90-10 mol-% units derived from C5-C20 monoolefin. 6. Use according to claim 5, wherein said copolymer includes 25-75 mol-% C3 or C4 monoolefin-derived units and 75-25 mol-% units derived from C5-C20 monoolefin. 7. Use according to claim 1, where said copolymer includes 10-90 mol-% butene-1 - derived units and 90-10 mol-% units derived from C8-C1 monoolefin. 8. Use according to claim 7, where said butene-1-derived units include 25-75 mol-% of said copolymer. 9. Use according to any one of claims 1-8, wherein the copolymer has a viscosity average molecular weight of from 500,000 to 10 million. 10. Use according to any one of claims 1-8, wherein an effective amount of at least one additional additive selected from the group consisting of (i) rust inhibitors, (ii) anti-oxidizing agent, (iii) solidification point depressants, and (iv) antiwear agents, is mixed with said single-use lubricating oil and with said copolymer.