FIELD OF THE INVENTION

This invention relates to biodegradable chain bar lubricant compositions and more particularly to chain bar lubricant formulations containing a triglyceride content that can be adjusted to provide an unusually low pour point to make it useful for cold weather applications or to maintain excellent lubricity characteristics even when used at high summer temperatures .

BACKGROUND OF THE INVENTION

Chainsaws, both those suitable for industrial or home uses, require constant lubrication of the chain and bar during use in order to mitigate wear and tear on both the chain and the bar. A typical chain bar lubricant composition has mineral oil as its base fluid. Existing plant-based chainsaw lubricants have characteristics that are inferior performance to petroleum-based lubricants and their use usually requires more frequent changes of chains and bars especially in commercial logging applications.

During use of a chainsaw, a constant stream of minuscule lubricant droplets spray off the chain and float in the atmosphere, before falling to the ground to be absorbed into the soil or seep into water tables. In petroleum based chainsaw lubricants, composition is not biodegradable. As a result, typical chain bar lubricant compositions remain in the environment after use for a great period of time causing considerable pollution, particularly of the waterbed. It's been estimated that one liter of such compositions is sufficient to render about 1 million liters of water unfit for human consumption.

Most existing chainsaw lubricants are not well suited for use in low temperature, e.g. <-24oC, conditions as they tend to solidify or get quite viscous. There is a real need for a lubricant which is environmentally safe and applicable to operations under low temperature conditions.

U.S. Pat. No. 3,860,521 provides an aqueous lubricating concentrate for lubricating

SUBSTITUTE SHEET ( RULE 26) continuously moving conveyor systems wherein said concentrate contains a fatty acid soap and a surfactant, wherein the improvement comprises the addition to said composition of mono- stearyl acid phosphate in an amount from about 0.15 to about 1.75 weight percent of the concentrate. The concentrate when diluted with water is then ready for use as a lubricating composition.

U.S. Pat. No. 5,641,734 describes a multi component chainsaw bar lubricant that contains several additives to improve performance - but does not disclose nor suggest any formulation that would be applicable to ultra-low operating temperatures.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a biodegradable triglyceride-based chain bar lubricant composition containing a blend of between one and ninety nine percent of one or more naturally occurring triglycerides and between ninety nine and zone percent of one or more partially hydrogenated triglycerides, respectively, that can be optimized to provide an unusually low pour point for use in winter climates, or to maintain excellent lubricity even at high temperatures for use in summer climates. The winter version is comprised primarily of naturally occurring triglyceride(s) and has an oleic content of at least 60% and a pour point of lower than minus 30°C, and preferably lower than minus 35°C, and a stearic acid content of the triglycerides contained therein of less than 5%. The summer version is comprised primarily of partially hydrogenated triglyce ride(s) and has an oleic content of less than 50%. The relative content of naturally occurring and partially hydrogenated triglycerides in the composition can be adjusted to have intermediate characteristics for use in intermediate climatic temperatures or applications. The lubricant composition also normally includes a viscosity modifying additive, a tackifier, a pour point depressant, and an anti-wear agent, and can also include a dispersant, an antioxidant, an anti-corrosion additive and other optional additives in particular cases. All compositional percentages stated in the specification and claims of this application are percentages by weight.

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SUBSTITUTE SHEET ( RULE 26) In the summer version of the present invention, there is provided lubricant composition adapted for use in warm climates that typically comprise a blend of naturally occurring and modified triglyceride oils and having a ratio of mono to poly unsaturated content of between 0.5/1.0 to 0.98/1.0. It has been found that, in contrast to teachings of the prior art that the triglyceride oils of a lubricant composition suitable for warm weather applications contain at least a 60 percent and preferably higher monounsaturated content, substantially improved performance in characteristics such as lubricity, metal wear performance, much reduced odor, reduced residue adhering to the lubricated surface and reduced spray of lubricant droplets during use are obtainable when the oleic content of the triglycerides is less than 50%.

DETAILED DESCRIPTION OF THE INVENTION

Generally, the present invention provides a biodegradable chain bar lubricant composition containing between 76% and 84%, preferably between 78% and 82%, by weight of at least one triglyceride; between 2.0% and 10.0% by weight of at least one viscosity modifying additive; between 3.0% and 10.0% by weight of at least one tackifier; between 1.8% and 3.0% by weight of at least one pour point depressant; and ; between 1.5% and 5.0% by weight of at least one anti-wear agent.

The term "biodegradable" describes a property which allows a compound to be broken down into smaller innocuous components which generally leave no long-lived toxic residues and thus no contamination of the environment. The industry wide biodegradability test employed for the instant invention is the CEC L33-T82.

(A) The Triglyceride

The triglyceride oils suitable for use in this invention are naturally occurring vegetable oils and modified vegetable oils. By "naturally occurring" it is meant that the triglycerides of the oils have not been subjected to hydrogenation or other chemical treatment that alters the di-and tri-unsaturation character. The seeds from which a naturally occurring vegetable oil is obtained may have been modified genetically. Hydrogenation of triglycerides in naturally occurring vegetable oils is the primary means of chemical modification.

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SUBSTITUTE SHEET ( RULE 26) In formulations suitable for cold weather use, naturally occurring triglycerides are preferred. The triglycerides are esters having at least one straight chain fatty acid moiety and a glycerol moiety wherein the fatty acid moiety contains R.sup.l, R.sup.2 and R.sup.3 which are saturated or unsaturated aliphatic hydrocarbon groups containing from about 8 to about 22 carbon atoms, preferably from about 12 to 22 carbon atoms.

Naturally occurring triglycerides having utility in this invention suitable for cold weather use are exemplified by vegetable oils that are preferably genetically modified such that they contain a higher-than-normal oleic acid content. That is, the R.sup.l, R.sup.2 and R.sup.3 groups are heptadecenyl groups and the R.sup.l COO. sup.-, R.sup.2 COO. sup.- and R.sup.3 COO. sup.- that are attached to the 1,2, 3, -propanetriyl groups -CH. sub.2 CHCH.sub.2 - are the residue of an oleic acid molecule, refined, bleached and deodorized (RBD) Canola oil, which has an about 60% oleic acid moiety, can also be used. Generally, the fatty acid moieties are such that the triglyceride has monounsaturated character preferably of at least 80 percent, more preferably 90 percent. Normal sunflower oil has an oleic acid content of 20-40 percent. By genetically modifying the seeds of sunflowers, a sunflower oil can be obtained wherein the oleic content is from about 80 percent up to about 90 percent. U.S. Pat. Nos. 4,627,192 and 4,743,402 are herein incorporated by reference for their disclosures directed to the preparation of high oleic sunflower oil.

For example, a triglyceride comprised exclusively of an oleic acid moiety has an oleic acid content of 100 percent and consequently a monounsaturated content of 100 percent. When the triglyceride is made up of acid moieties that are 70 percent oleic acid, 10 percent stearic acid, 5 percent palmitic acid, 7 percent linoleic acid and 8 percent hexadecenoic acid, the monounsaturated content is 78 percent. The preferred triglyceride oils for winter applications are genetically modified high oleic (at least 60 percent) acid triglyceride oils. Typical genetically modified high oleic or ricinoleic seed oils employed within the instant invention are high oleic safflower oil, high oleic or ricinoleic castor, high oleic corn oil, high oleic rapeseed oil, high oleic canola oil, high oleic sunflower oil, high oleic soybean oil, high oleic cottonseed oil, high oleic

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SUBSTITUTE SHEET ( RULE 26) lesquerella oil, high oleic meadowfoam oil and high oleic palm olein. In this case high ricinoleic castor is an ideal candidate source of oil. A preferred high oleic vegetable oil is an RBD high oleic soy or canola, or high oleic sunflower oil obtained from Helianthus sp. Another preferred high oleic vegetable oil is high oleic rapeseed oil obtained from Brassica campestris or Brassica napus, also available from SVO Enterprises as RS.RTM. high oleic rapeseed oil. RS 80 signifies a rapeseed oil wherein the acid moieties comprise 80 percent oleic acid.

Genetically modified vegetable oils have high oleic acid contents at the expense of the di- and tri- unsaturated acids. A normal sunflower oil has from 20-40 percent oleic acid moieties and from 50-70 percent linoleic acid moieties. This gives a 90 percent content of mono- and diunsaturated acid moieties (20+70 or 40+50). Genetically modifying vegetable oils generate a low di- or tri- unsaturated moiety vegetable oil. The genetically modified oils suitable for use in this invention have an oleic acid moietydinoleic acid moiety ratio of from about 2 up to about 90. A 60 percent oleic acid moiety content and 30 percent linoleic acid moiety content of a triglyceride oil gives a ratio of 2. A triglyceride oil made up of an 80 percent oleic acid moiety and 10 percent linoleic acid moiety gives a ratio of 8. A triglyceride oil made up of a 90 percent oleic acid moiety and 1 percent linoleic acid moiety gives a ratio of 90. The ratio for normal sunflower oil is 0.5 (30 percent oleic acid moiety and 60 percent linoleic acid moiety).

The chainsaw bar lubricant oils of this invention normally include additives such as a tackifier to reduce the rate at which the composition is ejected from the chainsaw by the movement of the chain, and preferably further includes some or all of a pour point depressant, a lubricity improver, a dispersant, an antioxidant and an anti-wear or anti-corrosion additive.

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SUBSTITUTE SHEET ( RULE 26) Iodine, yalue.ys.. Fatty. Add Components for B.B.D~Soy..Hyd.r.pg.e.natipn

Soy Component Graph

Above is a graph of the component weight percent content versus iodine value of the fatty acid components of an RBD soy oil for varying degrees of hydrogenation. Graphs of component weight percent contents of other vegetable oils, e.g. canola, would show similar trends for varying degrees of hydrogenation. As seen in the graph, as the degree of hydrogenation increases from right to left, the percentage content of oleic acid in the soy oil increases until it reaches a peak at a value of about 68 and then decreases somewhat; and the percentage content of polyunsaturates, consisting of the linoleic acid and linolenic acid, decreases from right to left with increasing hydrogenation.

The effect of the stearic acid content of the oil is also significant. The stearic acid content provides lubricity to the oil, but also increases its pour point. In chainsaw lubricants suitable for winter use, the stearic acid content typically needs to be below 5%, and requires the use of a pour point depressant additive. In summer chainsaw lubricant formulations, the stearic acid content can be somewhat higher, but still will typically require the use of at least some pour point depressant additive.

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SUBSTITUTE SHEET ( RULE 26) (B) The Viscosity Modifying Additive

The viscosity modifying composition functions to decrease the slope of the viscosity temperature relationship so that the oil is more viscous at higher temperature than it would be without the viscosity improver while at the same time not making the oil too thick at lower temperatures. In one aspect, Component (B) below, as (B-l) contemplates the provision of a nitrogen-containing ester of a carboxyl-containing interpolymer, said interpolymer having a reduced specific viscosity of from about 0.05 to about 2, such ester being substantially free of titratable acidity and being characterized by the presence within its polymeric structure of at least one of each of three pendant polar groups: (A) a relatively high molecular weight carboxylic ester group having at least 8 aliphatic carbon atoms in the ester radical, (B) a relatively low molecular weight carboxylic ester group having no more than 7 aliphatic carbon atoms in the ester radical, and (C) a carbonyl-polyamino group derived from a polyamino compound having one primary or secondary amino group, wherein the molar ratio of (A) :( B) :(C) is (60-90):(10-30) :(2-15), respectively.

An important element of the nitrogen-containing ester is that the ester is a mixed ester, i.e., one in which there is the combined presence of both a high molecular weight ester group and a low molecular weight ester group, particularly in the ratio as stated above. Such combined presence is important to the viscosity properties of the mixed ester, both from the standpoint of its viscosity modifying characteristics and from the standpoint of its thickening effect upon lubricating compositions in which it is used as an additive.

In reference to the size of the ester groups the number of carbon atoms in an ester radical is the combined total of the carbon atoms of the carbonyl group and the carbon atoms of the ester group i.e., the (OR) group.

Another important element of Component (B-l) is the presence of a polyamino group derived from a particular polyamino compound, i.e., one in which there is one primary or secondary

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SUBSTITUTE SHEET ( RULE 26) amino group and at least one mono-functional amino group. Such polyamino groups, when present in the nitrogen-containing esters of (B-l) in the proportion stated above enhances the dispersability of such esters in lubricant compositions and additive concentrates for lubricant compositions.

Still another important element of Component (B-l) is the extent of esterification in relation to the extent of neutralization of the unesterified carboxyl groups of the carboxyl-containing interpolymer through the conversion thereof to polyamino-containing groups. For convenience, the relative proportions of the high molecular weight ester group to the low molecular weight ester group and to the polyamino group are expressed in terms of molar ratios of (60-90):(10- 30) :(2-15), respectively. The preferred ratio is (70-80) : (15-25 ) :5. The linkage described as the carbonyl-polyamino group may be imide, amide, or amidine and inasmuch as any such linkage is contemplated as potentially being useful in the present invention, the term "carbonyl polyamino" is thought to be a convenient, generic expression useful for the purpose of defining the inventive concept. In a particularly advantageous embodiment of the invention such linkage is imide or predominantly imide.

Still another significant element of Component (B-l) is the molecular weight of the carboxyl- containing interpolymer. For convenience, the molecular weight is expressed in terms of the "reduced specific viscosity" of the interpolymer which is a widely recognized means of expressing the molecular size of a polymeric substance. As used herein, the reduced specific viscosity (abbreviated as RSV) wherein the relative viscosity is determined by measuring, by means of a dilution viscometer, the viscosity of a solution of one gram of the interpolymer in 10 ml. of acetone and the viscosity of acetone at 30. degree..+-.0.02. degree. C. For purpose of computation by the above formula, the concentration is adjusted to 0.4 gram of the interpolymer per 100 ml. of acetone. A more detailed discussion of the reduced specific viscosity, also known as the specific viscosity, as well as its relationship to the average molecular weight of an interpolymer, appears in Paul J. Flory, Principles of Polymer Chemistry, (1953 Edition) pages 308 et seq.

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SUBSTITUTE SHEET ( RULE 26) While interpolymers having reduced specific viscosity of from about 0.05 to about 2 are contemplated in Component (B-l), the preferred interpolymers are those having a reduced specific viscosity of from about 0.3 to about 1. In most instances, interpolymers having a reduced specific viscosity of from about 0.5 to about 1 are particularly preferred.

From the standpoint of utility, as well as for commercial and economic reasons, nitrogencontaining esters in which the high molecular weight ester group has from 8 to 24 aliphatic carbon atoms, the low molecular weight ester group has from 3 to 5 carbon atoms, and the carbonyl polyamino group is derived from a primary-aminoalkyl-substituted tertiary amine, particularly heterocyclic amines, are preferred. Specific examples of the high molecular weight carboxylic ester group, i.e., the (OR) group of the ester radical (i.e., -(O)(OR)) include heptyloxy, isooctyloxy, decyloxy, dodecyloxy, tridecyloxy, tetradecyloxy, pentadecyloxy, octadecyloxy, eicosyloxy, tricosyloxy, tetracosyloxy, etc. Specific examples of low molecular weight groups include methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, sec-butyloxy, iso-butyloxy, n- pentyloxy, neo-pentyloxy, n-hexyloxy, cyclohexyloxy, xyxlopentyloxy, 2-methyl-butyl- 1-oxy, 2,3-dimethyl-butyl-l-oxy, etc. In most instances, alkoxy groups of suitable size comprise the preferred high and low molecular weight ester groups. Polar substituents may be present in such ester groups. Examples of polar substituents are chloro, bromo, ether, nitro, etc.

(C) The Tackifier

The tackifier provides adhesiveness and anti-drip characteristics to the chain bar lubricant.

The tackifier is preferably a substituted succinic acylating agent which can be characterized by the presence within its structure of two groups or moieties. The first group or moiety is referred to herein, for convenience, as the "substituent group(s)" and is derived from a polyalkene. The polyalkene from which the substituted groups are derived is characterized by a Mn (number average molecular weight) value of from 1300 to about 5000 and a Mw/Mn value of about 1.5 to about 4.

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SUBSTITUTE SHEET ( RULE 26) One of the unsatisfied valences forms a carbon-to-carbon bond with a carbon atom in the substituent group. While other such unsatisfied valence may be satisfied by a similar bond with the same or different substituent group, all but the said one such valence is usually satisfied by hydrogen; ie., -H.

The substituted succinic acylating agents are characterized by the presence within their structure of at least 1.3 succinic groups (that is, groups corresponding to Formula I) for each equivalent weight of substituent groups. For purposes of this invention, the number of equivalent weights of substituent groups is deemed to be the number corresponding to the quotient obtained by dividing the Mn value of the polyalkene from which the substituent is derived into the total weight of the substituent groups present in the substituted succinic acylating agents. Thus, if a substituted succinic acylating agent is characterized by a total weight of substituent group of 40,000 and the Mn value for the polyalkene from which the substituent groups are derived is 2000, then that substituted succinic acylating agent is characterized by a total of 20 (40,000/2000=20) equivalent weights of substituent groups. Therefore, that particular succinic acylating agent must also be characterized by the presence within its structure of at least 26 succinic groups to meet one of the requirements of the novel succinic acylating agents of this invention.

(D) The Pour Point Depressant

The pour point depressant (PPD) functions by acting as a nucleating agent which promotes the formation of small wax crystals; the PPD does not prevent wax crystal formation. Controlling the volume of the crystal is key in maintaining lubricant flow.

The PPD is similar to the viscosity modifying composition in all respects except that the carboxyl containing interpolymer has a reduced specific viscosity of from about 0.05 to about 1 and being characterized by the presence within its polymeric structure of at least one of each of the following groups which are derived from the carboxyl groups of said interpolymer:

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SUBSTITUTE SHEET ( RULE 26) (A') a carboxylic ester group, said carboxylic ester group having at least eight aliphatic carbon atoms in the ester radical, and

(B') a carbonyl-polyamino group derived from a poly-amino compound having one primary or secondary amino group and at least one mono-functional amino group, wherein the molar ration of carboxyl groups of said interpolymer esterified to provide (A') to carboxyl groups of said interpolymer neutralized to provide ( B') is in the range of about 85:15 to about 99:1.

(E) The Antiwear Agent

The antiwear agent provides a sacrificial film on the metal surface. This film is then removed during asperity contact thereby reducing the removal of metal from the surface.

In one aspect the antiwear agent is a sulfurized composition. Useful sulfurized compositions for use in connection with the present invention are prepared by reacting, at about 100. degree. - 250. degree. C., sulfur with a mixture comprising (A) 100 parts by weight of at least one fatty acid ester, (B) about 0-50 parts by weight of at least one fatty acid, and (C) about 25-400 parts by weight of at least one aliphatic olefin containing about 8-36 carbon atoms.

EXAMPLES

Examples of chain saw lubricants having a soy oil -based composition having an oleic content of about 35wt%, and a high oleic canola-based oil having an oleic content of about 64wt% were prepared with the same additive package and compared to a leading brand in the market. The combination of high oleic canola oil together with the additive package gave a totally unexpected reduction in overall pour point to a level that has not been reported in the industry.

The additive charge for the soy and canola-based blends was as follows:

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SUBSTITUTE SHEET ( RULE 26) Tackifier V-584 3.0-10.0 %wt

Viscosity Modifier V515 2.0-10.0 % wt

Anti Wear SGP-568 1.5-5.0 %wt

Cold Flow Improver Viscoplex 10-310 2.0-3.0 %wt

The composition of the soy and canola-based blends was as follows:

SUBSTITUTE SHEET ( RULE 26)

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SUBSTITUTE SHEET (RULE 26) Referring to the Soy Component Graph, the RBD soy oil employed in the Example had been partially hydrogenated to the point where, as measured using iodine values, the oleic content was 35%, the linoleic content was 43%, the linolenic content was 3%, palmitic acid content was 10% and the stearic acid component so that the ratio of the oleic acid content to the polyunsaturated content of the oil was 0.76.

Three runs of a Tribology test were performed to measure potential chainsaw blade metal wear resulting from the use of the lubricant of the Example versus that resulting from the use of a premium quality commercial Bio-Pro Bar & Chain Oil. The tribology test uses a Falex Block-on- Ring tribometer in which the wear scar on the metal block submerged in the test lubricant composition in contact with a rotating ring is examined after a 6hr test time. The extent of the block wear was measured by a white light interferometer as photo visualizations, and as calculated displaced volumetric metal loss.

Metal Loss, um ³ xl0 ⁷

Sample RBD Soy Oil Bio-Pro

Run 1 2.14 2.88

Run 2 2.42 3.40

Run 3 1.72 2.00

Average 2.09 2.76

24% Less Wear with RBD Soy Oil

The 24% reduction in wear resulting from the use of the lubricant of the present invention versus that experienced with what is believed to be the leading current vegetable oil based chainsaw lubricant, would result in commercial logging operations in a significant decrease in the required frequency replacing the blade, and a corresponding increase in efficiency of the operation.

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SUBSTITUTE SHEET ( RULE 26) When compared to a petroleum based chain saw lubricant having similar viscometric properties and containing the same additive package, the lubricant of the present invention causes less than one half the wear during back-to-back Block on Ring Tribometer tests.

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SUBSTITUTE SHEET ( RULE 26)