LUBRICANT COMPOSITIONS INCLUDING POLYMERIC DISPERSANTS

Abstract

A lubricant composition includes water, graphite, a thickener, and a polymeric dispersant comprising monomeric structural units derived from acrylic acid and monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid.

Claims

1. A lubricant composition, comprising: water, graphite; a thickener, and a polymeric dispersant comprising monomeric structural units derived from acrylic acid and monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid.

2. The lubricant composition of claim 1, wherein the lubricant composition comprises 20 wt % to 60 wt % water based on a total weight of the lubricant composition.

3. The lubricant composition of claim 1, wherein the lubricant composition comprises 10 wt % to 60 wt % of graphite based on a total weight of the lubricant composition.

4. The lubricant composition of claim 3, wherein the graphite has a D90 particle diameter of from 0.5 m to 5.0 m.

5. The lubricant composition of claim 1, wherein the polymeric dispersant has a weight average molecular weight of 3,000 g/mol to 6,000 g/mol as measured according to gel permeation chromatography.

6. The lubricant composition of claim 1, wherein the lubricant composition comprises 0.01 wt % to 1.0 wt % of the dispersant based on a total weight of the lubricant composition.

7. The lubricant composition of claim 1, wherein the polymeric dispersant comprises 20 wt % to 30 wt % of monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid based on a total weight of the polymeric dispersant.

8. The lubricant composition of claim 7, wherein the polymeric dispersant has a weight average molecular weight of 4,000 g/mol to 5,000 g/mol as measured according to gel permeation chromatography

9. The lubricant composition of claim 1, wherein the polymeric dispersant comprises monomeric structural units derived from N-tert-butylacrylamide.

10. The lubricant composition of claim 9, wherein the polymeric dispersant comprises 1 wt % to 30 wt % of the monomeric structural units derived from N-tert-butylacrylamide based on a total weight of the polymeric dispersant.

Description

DETAILED DESCRIPTION

[0020] As used herein, the term and/or, when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A. B, and C in combination.

[0021] All ranges include endpoints unless otherwise stated.

[0022] As used herein, the term weight percent (wt %) designates the percentage by weight a component is of a total weight of the polymeric composition unless otherwise specified.

[0023] As used herein, Chemical Abstract Services registration numbers (CAS #) refer to the unique numeric identifier as most recently assigned as of the priority date of this document to a chemical compound by the Chemical Abstracts Service.

Lubricant Composition

[0024] The present disclosure is directed to a lubricant composition. The lubricant composition comprises water, graphite, a thickener, and a polymeric dispersant comprising monomeric structural units derived from acrylic acid and monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid. The lubricant composition may comprise 20 wt % to 60 wt % water based on a total weight of the lubricant composition. For example, the lubricant composition comprises 20 wt % or greater, or 25 wt % or greater, or 30 wt % or greater, or 35 wt % or greater, or 40 wt % or greater, or 45 wt % or greater, or 50 wt % or greater, or 55 wt % or greater, while at the same time, 60 wt % or less, or 55 wt % or less, or 50 wt % or less, or 45 wt % or less, or 40 wt % or less, or 35 wt % or less, or 30 wt % or less, or 25 wt % or less of water based on a total weight of the lubricant composition. The lubricant composition may comprise one or more other additives designed to alter a property of characteristic of the lubricant composition.

Thickener

[0025] The thickener is included in the lubricant composition to aid in the application and retention of the lubricant composition on surfaces. The thickener may comprise a polysaccharide such as agar, sodium alginate, rhamsam gum, locust bean gum, carrageenan, gum arabic, neem gum, gum chatti, caranna, galactomannan, gum tragacanth, karaya gum, guar gum, welan gum, beta-glucan, cellulose, chicle gum, kino gum, dammar gum, glucomannan, acacia gum, cassia gum, mastic gum, spruce gum, pysllium seed husks, gellan gum, xanthan gum, diutan gum, fenugreek gum, ghatti gum, methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, karaya gum, konjac gum, pectin and combinations thereof. Additionally or alternatively, the thickener may also include other viscosity modifying components such as polyethylene glycol, polyacrylic acid, polyethyleneimine, polyvinyl alcohol, polyacrylamides, carboxyvinyl polymers, poly(vinylpyrrolidinone) and copolymers, polyoxypropylene and combinations thereof.

[0026] The lubricant composition may comprise 0.1 wt % to 5.0 wt % thickener based on a total weight of the lubricant composition. For example, the lubricant composition may comprises 0.1 wt % or greater, or 0.2 wt % or greater, or 0.4 wt % or greater, or 0.6 wt % or greater, or 0.8 wt % or greater, or 1.0 wt % or greater, or 1.5 wt % or greater, or 2.0 wt % or greater, or 2.5 wt % or greater, or 3.0 wt % or greater, or 3.5 wt % or greater, or 4.0 wt % or greater, or 4.5 wt % or greater, while at the same time, 5.0 wt % or less, or 4.5 wt % or less, or 4.0 wt % or less, or 3.5 wt % or less, or 3.0 wt % or less, or 2.5 wt % or less, or 2.0 wt % or less, or 1.5 wt % or less, or 1.0 wt % or less, or 0.5 wt % or less of the thickener based on the total weight of the lubricant composition.

Graphite

[0027] The lubricant composition comprises graphite. The graphite may have spherical shape, a plate like shape, an oblong shape and/or an irregular shape. The particles of the graphite may have a D90 of from 0.5 microns (m) to 10 m. As used herein, the term D90 means that 90% of the graphite particles have a diameter or longest length dimension smaller than the indicated value and 10% of the particles have a diameter or longest length dimension greater than the indicated value. The graphite may have a D90 particle size of 0.5 m or greater, or 1.0 m or greater, or 1.5 m or greater, or 2.0 m or greater, or 2.5 m or greater, or 3.0 m or greater, or 3.5 m or greater, or 4.0 m or greater, or 4.5 m or greater, or 5.0 m or greater, or 5.5 m or greater, or 6.0 m or greater, or 6.5 m or greater, or 7.0 m or greater, or 7.5 m or greater, or 8.0 m or greater, or 8.5 m or greater, or 9.0 m or greater, or 9.5 m or greater, while at the same time, 10 m or less, or 9.5 m or less, or 9.0 m or less, or 8.5 m or less, or 8.0 m or less, or 7.5 m or less, or 7.0 m or less, or 6.5 m or less, or 6.0 m or less, or 5.5 m or less, or 5.0 m or less, or 4.5 m or less, or 4.0 m or less, or 3.5 m or less, or 3.0 m or less, or 2.5 m or less, or 2.0 m or less, or 1.5 m or less, or 1.0 m or less. The D90 particle size of the graphite is determined using a Malvern Mastersizer laser diffraction particle size analyzer.

[0028] The lubricant composition comprises 10 wt % to 60 wt % of graphite based on a total weight of the lubricant composition. For example, the lubricant composition comprises 10 wt % or greater, or 15 wt % or greater, or 20 wt % or greater, or 25 wt % or greater, or 30 wt % or greater, or 35 wt % or greater, or 40 wt % or greater, or 45 wt % or greater, or 50 wt % or greater, or 55 wt % or greater, while at the same time, 60 wt % or less, or 55 wt % or less, or 50 wt % or less, or 45 wt % or less, or 40 wt % or less, or 35 wt % or less, or 30 wt % or less, or 25 wt % or less, or 20 wt % or less, or 15 wt % or less of graphite based on a total weight of the lubricant composition.

Dispersant

[0029] The lubricant composition comprises the dispersant. The dispersant is a polycarboxylate dispersant comprising monomeric structural units derived from acrylic acid and monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid. The dispersant is a polymer. As used herein, the term polymer means a macromolecular compound comprising a plurality of monomers of the same or different type which are bonded together, and includes homopolymers and interpolymers. As used herein, the term interpolymer means a polymer comprising at least two different monomer types bonded together. Interpolymer includes copolymers (usually employed to refer to polymers prepared from two different monomer types), and polymers prepared from more than two different monomer types (e.g., terpolymers (three different monomer types) and quaterpolymers (four different monomer types)). The dispersant may comprise monomeric structural units derived from acrylic acid, 2-acrylamido-2-methylpropane sulfonic acid, N-tert-butylacrylamide, other monomer precursors and combinations thereof. The dispersant may be free of sulfonate ionic groups or moieties.

[0030] The dispersant may comprise from 40 wt % to 80 wt % of monomeric structural units derived from acrylic acid based on the total weight of the dispersant. For example, the dispersant may comprise 40 wt % or greater, or 45 wt % or greater, or 50 wt % or greater, or 55 wt % or greater, or 60 wt % or greater, or 65 wt % or greater, or 70 wt % or greater, or 75 wt % or greater, while at the same time, 80 wt % or less, or 75 wt % or less, or 70 wt % or less, or 65 wt % or less, or 60 wt % or less, or 55 wt % or less, or 50 wt % or less, or 45 wt % or less of monomeric structural units derived from acrylic acid based on the total weight of the dispersant.

[0031] The dispersant may comprise from 10 wt % to 40 wt % of monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid based on the total weight of the dispersant. For example, the dispersant may comprise 10 wt % or greater, or 15 wt % or greater, or 20 wt % or greater, or 25 wt % or greater, or 30 wt % or greater, or 35 wt % or greater, while at the same time, 40 wt % or less, or 35 wt % or less, or 30 wt % or less, or 25 wt % or less, or 20 wt % or less, or 15 wt % or less of monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid based on the total weight of the dispersant.

[0032] The dispersant may comprise from 1 wt % to 30 wt % of monomeric structural units derived from N-tert-butylacrylamide based on the total weight of the dispersant. For example, the dispersant may comprise 1 wt % or greater, or 5 wt % or greater, or 10 wt % or greater, or 15 wt % or greater, or 20 wt % or greater, or 25 wt % or greater, while at the same time, 30 wt % or less, or 25 wt % or less, or 20 wt % or less, or 15 wt % or less, or 10 wt % or less, or 5 wt % or less of monomeric structural units derived from N-tert-butylacrylamide based on the total weight of the dispersant.

[0033] The dispersant may comprise from 40 wt % to 80 wt % of monomeric structural units derived from acrylic acid, from 10 wt % to 40 wt % of monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid, and 0 wt % to 30 wt % of monomeric structural units derived from N-tert-butylacrylamide based on the total weight of the dispersant. The dispersant may comprise any value within the wt % ranges identified above for each monomeric structural unit. The dispersant may be end capped with poly(phthalaldehyde), Xylene, other end capping agents and combinations thereof.

[0034] The dispersant may have a weight average molecular weight of 3,000 grams per mole (g/mol) to 6,000 g/mol as measured according to gel permeation chromatography. For example, the weight average molecular weight of the dispersant may be 3,000 g/mol or greater, or 3,500 g/mol or greater, or 4,000 g/mol or greater, or 4,500 g/mol or greater, or 5,000 g/mol or greater, or 5,500 g/mol or greater, while at the same time, 6,000 g/mol or less, or 5.500 g/mol or less, or 5,000 g/mol or less, or 4,500 g/mol or less, or 4,000 g/mol or less, or 3,500 g/mol or less as measured according to gel permeation chromatography.

[0035] The dispersant may be suspended in a suspension agent such as water. In such a case, the amount of dispersant in the suspension agent is referred to as the solids content and is expressed as a weight percent of the dispersant based on the total weight of the combined dispersant and suspension agent. The solids content may be from 20 wt % to 60 wt % based on a total weight of the combined dispersant and suspension agent. For example, the solids content may be 20 wt % or greater, or 25 wt % or greater, or 30 wt % or greater, or 35 wt % or greater, or 40 wt % or greater, or 45 wt % or greater, or 50 wt % or greater, or 55 wt % or greater, while at the same time, 60 wt % or less, or 55 wt % or less, or 50 wt % or less, or 45 wt % or less, or 40 wt % or less, or 35 wt % or less, or 30 wt % or less, or 25 wt % or less based on the total weight of combined dispersant and suspension agent.

[0036] The lubricant composition may comprise 0.1 wt % to 5.0 wt % dispersant based on a total weight of the lubricant composition. For example, the lubricant composition comprises 0.1 wt % or greater, or 0.2 wt % or greater, or 0.3 wt % or greater, or 0.4 wt % or greater, or 0.5 wt % or greater, or 0.6 wt % or greater, or 0.7 wt % or greater, or 0.8 wt % or greater, or 0.9 wt % or greater, or 1.0 wt % or greater, or 1.5 wt % or greater, or 2.0 wt % or greater, or 2.5 wt % or greater, or 3.0 wt % or greater, or 3.5 wt % or greater, or 4.0 wt % or greater, or 4.5 wt % or greater, while at the same time, 5.0 wt % or less, or 4.5 wt % or less, or 4.0 wt % or less, or 3.5 wt % or less, or 3.0 wt % or less, or 2.5 wt % or less, or 2.0 wt % or less, or 1.5 wt % or less, or 1.0 wt % or less, or 0.9 wt % or less, or 0.8 wt % or less, or 0.7 wt % or less, or 0.6 wt % or less, or 0.5 wt % or less, or 0.4 wt % or less, or 0.3 wt % or less, or 0.2 wt % or less of the dispersant based on the total weight of the lubricant composition.

EXAMPLES

Materials

[0037] The following materials were used in the examples.

[0038] Graphite is a powder of graphite particles having a D90 of 5.0 m and is commercially available from Molygraph Lubricants, Mumbai, India.

[0039] Thickener is xanthan gum commercially available from Loba Chemie Mumbai, India.

[0040] Dispersant 1 is a solution of an alkylammonium salt of a polycarboxylic acid sold under the tradename ANTI-TERRA and is commercially available from BYK-Chemie GmbH, Wesel, Germany.

[0041] Dispersant 2 is a 97 wt % actives powder having Structure (T), a CAS # of 9084-06-4 and is available from The Dow Chemical Company, Midland Michigan.

##STR00001##

[0042] Dispersant 3 is pure sodium dodecyl sulfate having a CAS # of 151-21-3 and is available from Loba Chemie Mumbai, India.

[0043] Dispersant 4 is a homopolymer of monomeric structure units derived from acrylic acid that is end capped with poly(phthalaldehyde), has a weight average molecular weight of 2000 g/mol, has a 47-49 wt % solids content and is available from The Dow Chemical Company, Midland Michigan.

[0044] Dispersant 5 is a copolymer of approximately 75 wt % to 80 wt % of monomeric structural units derived from acrylic acid and 20 wt % to 25 wt % of monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid. Dispersant 5 has a weight average molecular weight of 4500 g/mol, is end capped with poly(phthalaldehyde) and has a solids content of 40 wt % to 45 wt % based on the total weight of the dispersant. Dispersant 5 is available from The Dow Chemical Company, Midland Michigan.

[0045] Dispersant 6 is a terpolymer of approximately 60 wt % to 70 wt % of monomeric structural units derived from acrylic acid, 25 wt % to 30 wt % of monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid and 5 wt % to 10 wt % of monomeric structural units derived from N-tert-butylacrylamide. Dispersant 6 has a weight average molecular weight of 4500 g/mol, is end capped with poly(phthalaldehyde) and a solids content of 40 wt % to 45 wt % based on the total weight of the dispersant. Dispersant 6 is available from The Dow Chemical Company, Midland Michigan.

[0046] Dispersant 7 is a terpolymer of approximately 55 wt % to 65 wt % of monomeric structural units derived from acrylic acid, 15 wt % to 25 wt % of monomeric structural units derived from 2-acrylamido-2-methylpropane sulfonic acid and 15 wt % to 25 wt % of monomeric structural units derived from N-tert-butylacrylamide. Dispersant 7 has a weight average molecular weight of 5000 g/mol and a solids content of 40 wt % to 50 wt % based on the total weight of the dispersant. Dispersant 7 is available from The Dow Chemical Company, Midland Michigan.

Sample Preparation

[0047] The examples were prepared by first combining the thickener, the dispersant and a portion of the water and then mixing the solution for 1 minute using a stirrer. Next, the graphite powder was added slowly to the solution and mixed until a paste was formed. Next, the graphite paste was diluted with the remaining water and mixed using an overhead stirrer to form a dispersion having the composition listed in the Table 1. The diluted paste was then added to a 100 milliliter (ml) volumetric flask and filled to the 100 ml line.

Test Method

[0048] Sedimentation Test: The Sedimentation Test determines what percentage of the dispersion remains dispersed after a predetermined period of time. The 100 ml volumetric flask is filled to the 100 ml mark with the example and the flask is left undisturbed for the indicated period of time. The amount of example remaining dispersed is measured by visually observing the phase separation interface between a clear or hazy water phase and a dispersed graphite phase. The phase separation is determined by examining at what ml demarcation the graphite dispersion phase and water phase is at after an identified period of time, dividing by the initial 100 ml and multiplying by 100. For example, if the interface of the graphite dispersion phase and the water phase is at 95 ml, then 95% of the dispersion resisted phase separation. An example is considered to have passed the Sedimentation Test if 80% of the example remains in the graphite dispersion phase after 24 hours (i.e., 1 day).

Results

[0049] Table 1 below provides the composition of each comparative example (CE) and each inventive example (IE) in weight percents of components while Table 2 provides the performance data of each IE and CE. The data of Table 2 provides the percent of the example remaining in the graphite dispersion phase. The entry nm indicates that a particular time interval was not measured.

TABLE-US-00001 TABLE 1 Component CE1 CE2 CE3 CE4 CES CE6 CE7 CE8 IE1 IE2 IE3 IE4 IE5 IE6 IE7 IE8 Graphite 30 50 30 50 30 50 30 50 30 50 30 50 30 50 30 50 Thickener 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Dispersant 0.5 2.0 1 Dispersant 0.5 2.0 2 Dispersant 0.5 2.0 3 Dispersant 0.5 2.0 4 Dispersant 0.5 2.0 5 Dispersant 0.5 2.0 6 Dispersant 0.5 2.0 7 Water 69 49 68.5 47 68.5 47 68.5 47 68.5 47 68.5 47 68.5 47 68.5 47

TABLE-US-00002 TABLE 2 Time (hrs) CE1 CE2 CE3 CE4 CE5 CE6 CE7 CE8 CE9 CE10 IE1 IE2 IE3 IE4 IE5 IE6 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 0.16 80 80 90 85 90 90 90 90 90 90 100 100 100 100 100 100 12 35 35 80 35 80 80 80 70 80 80 100 100 100 100 100 100 24 30 30 70 30 50 60 25 18 50 50 100 100 100 100 100 100

[0050] As can be seen from Tables 1 and 2, IE1-IE6 drastically outperform CE1-CE10 in terms of producing a lubricant composition that passes the Sedimentation Test as indicated by IE1-IE6 all maintaining greater than 80% graphite dispersion after 24 hours. CE1 and CE2 demonstrate a baseline for the stability that can be expected from an aqueous graphite dispersion when no dispersants are included. CE4, CE7 and CE8 all demonstrate that the inclusion of certain dispersants can have no effect on dispersion stability or actually decrease the stability of graphite in water relative to dispersions having no dispersant as evidenced by lower percentages of retained graphite dispersion phases of CE4, CE7 and CE8 relative to CE1 and CE2, CE3, CE5, CE6, CE9 and CE10 all exhibit better dispersion stability than the control samples CE1 and CE2, but fail to achieve the stability desired by the Sedimentation Test.

[0051] Unlike CE1-CE10, each of IE1-IE6 is able to maintain 80% or greater of the graphite dispersion phase after 24 hour of testing and therefore pass the Sedimentation Test. Such a result is surprising because despite the variety of types of dispersants tested, the polymeric dispersants which are free of phenyl or aromatic ring structures perform the best despite the suggestion to the contrary by the prior art. Even more surprising is that despite Dispersant 2 (i.e. CE5 and CE6) including multiple aromatic structures and ionic sulfonate moieties, the dispersants of IE1-IE6 exhibit better performance than CE2 without aromatic or ionic sulfonate moieties.