Lubricating and low coefficient of friction coating composition for rigid substrates

Abstract

A coating composition for coating rigid substrates, including a binder resin, a lubricating component including a wax, and a solvent. The coating composition may further include a silicone resin. The binder resin is at least one of a polyamide imide, epoxy, silicone polyester, and polyurethane resin. The wax is at least one of a carnauba wax, a polyethylene wax, polypropylene wax, polyamide wax, and a Fischer-Tropsch wax. The coating composition is wear resistant and is substantially free of per-fluoroalkyl substances (PFAS) and N-methyl pyrrolidone (NMP).

Description

LUBRICATING AND LOW COEFFICIENT OF FRICTION COATING COMPOSITION FOR RIGID SUBSTRATES CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No.63 / 512,505 entitled “LUBRICATING AND LOW COEFFICIENT OF FRICTION COATING COMPOSITION FOR RIGID SUBSTRATES”, filed on July 7, 2023, and U.S. Provisional Application No.63 / 591,146 entitled “LUBRICATING AND LOW COEFFICIENT OF FRICTION COATING COMPOSITION FOR RIGID SUBSTRATES”, filed on October 18, 2023, both of which are incorporated by reference in their entireties. GOVERNMENT LICENSE RIGHTS

[0002] This invention was made with government support under Government Contract No. W911NF-17-2-0227 awarded by the U.S. Army Contracting Command on behalf of the U.S. Army Research Laboratory (ARL). The government may have certain rights in the invention. FIELD

[0003] The present disclosure relates to a lubricating coating composition with a low coefficient of friction, which may be applied to rigid substrates. BACKGROUND

[0004] Rigid metallic parts of mechanical devices may experience a variety of contact and frictional forces that can cause wear and deterioration upon sustained use. Coatings may be applied to these metal parts to enhance wear resistance, prevent premature failure, and / or suppress noise. Known coatings typically contain per / polyfluoroalkyl substances (PFAS) and / or solvents such as N-methyl pyrrolidone (NMP) which are progressively subjected to increased regulation.

[0005] Therefore, improvements in such coatings are desired.SUMMARY

[0006] The present disclosure provides a coating composition for a rigid substrate, including a binder resin, a lubricating component including a wax, and a solvent. The binder resin is selected from polyamide imide, epoxy, silicone polyester, and polyurethane resin. The wax may be at least one of a carnauba, polyethylene, and Fisher-Tropsch wax. The lubricating component further includes a silicone resin. The coating composition is wear resistant and substantially free of perfluoroalkyl substances and N-methyl pyrrolidone.

[0007] In one form thereof, the present disclosure provides a method of coating a rigid substrate including applying a coating composition to the rigid substrate and curing the coating composition at a temperature from 170oC to 240oC. The coating composition includes a binder resin, a lubricating component including a wax, and a solvent.

[0008] In another form thereof, the present disclosure also provides a coated rigid substrate including a rigid substrate and a coating on the rigid substrate. The coating on the rigid substrate includes a binder resin and a lubricating component including a wax. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the disclosure itself will be better understood by reference to the following description taken in conjunction with the accompanying drawings. These above-mentioned and other features of the disclosure may be used in any combination or permutation.

[0010] FIG. 1 is a graph of friction test results illustrating the coefficient of friction versus time for comparative coating 1 and inventive coatings 1-3;

[0011] FIG. 2 is a graph of friction test results illustrating the coefficient of friction versus time for comparative coating 1 and inventive coatings 3-4;

[0012] FIG. 3 is a graph of friction test results illustrating the coefficient of friction versus time for comparative coating 2 and inventive coatings 3 and 5;

[0013] FIG. 4 is a graph of friction test conducted at room temperature results illustrating the coefficient of friction versus time for comparative coating 3 and inventive coatings 6-11;

[0014] FIG. 5 is a graph of friction test conducted at room temperature results illustrating the coefficient of friction versus time for comparative coating 4 and inventive coatings 12-15; and

[0015] FIG.6 is a graph of friction test conducted at elevated temperature of 150oC results illustrating the coefficient of friction versus time for comparative coating 5 and inventive coatings 16-20.

[0016] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate the disclosure, and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner. DETAILED DESCRIPTION

[0017] The present disclosure provides a coating composition with a low coefficient of friction, which may be applied to rigid substrates.

[0018] I. Definitions

[0019] For purposes of the following detailed description, it is to be understood that the disclosure may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term “about.” For example, numerical ranges provided for weight percentages of components or amounts of components added should be construed as being modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0020] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.

[0021] Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges from (and including) the recited minimum value of 1 to therecited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

[0022] The use of the singular includes the plural and plural encompasses singular, unless specifically stated otherwise. In addition, the use of “or” means “and / or” unless specifically stated otherwise, even though “and / or” may be explicitly used in certain instances.

[0023] “Wax” is used herein to describe synthetic or naturally occurring materials formed of a mixture of alkanes of various chain lengths and / or a modified alkane which also includes other functional groups such as esters and / or amines in the chains, and which may demonstrate phase change characteristics, wherein the waxes tend to be solid at room temperature (20oC), have a melting point above about 40oC, and are able to absorb heat while showing little volume change during melting.

[0024] “Carnauba wax” is a naturally occurring wax including, as an exemplary blend, aliphatic esters (40 wt.%), diesters of 4-hydroxycinnamic acid (21.0 wt.%), ω- hydroxycarboxylic acids (13.0 wt.%), and fatty alcohols (12 wt.%).

[0025] “Fischer-Tropsch (FT) wax” is a purely synthetic polymer of carbon monoxide and hydrogen that could be considered a mineral wax. FT wax as long-chain aliphatic hydrocarbons with relatively short sidechains.

[0026] “Polyethylene wax” is a low molecular weight synthetic polymer containing ethylene monomer chains. The typical melting point of polyethylene wax is in the range of 90-150oC.

[0027] “PFAS” is used herein to describe per- and polyfluorinated substances, including synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain, for example perfluorinated monomers and oligomers such as perfluorooctanoic acid.

[0028] “Wet” coating composition is used herein to describe a liquid coating composition before it is cured.

[0029] “Dry” coating composition is used herein to describe a coating composition after it is cured.

[0030] II. Composition of Coating

[0031] The present disclosure provides a PFAS free coating composition that offers increased wear resistance and lubrication over traditional PFAS coating compositions. The coating composition may comprise a binder resin, a lubricating component, and a solvent.

[0032] A. Binder Resin

[0033] Binder resins provide adhesion to a substrate and improve the mechanical properties, such as elongation, and may be self-curable or cure with the aid of a curing agent. The binder resin may allow the coating to follow the elongation of a coated belt during operation without cracking or disbanding or suffering thermo-mechanical fatigue. A binder resin is referred to herein interchangeably as a ‘binder’, ‘resin binder’ or ‘binder resin’, ‘base’, or ‘binder system’ and, depending on the amount of lubricating component desired, may provide the bulk of the present coatings when applied to a substrate.

[0034] The binder resin of the present disclosure may be selected from a polyamide imide, epoxy, silicone polyester, polyurethane, and combinations thereof.

[0035] The coating compositions provided by the present disclosure may comprise a weight percentage of binder resin from 20 wt. %, 25 wt. %, 30 wt. %, 35 wt. % to 40 wt. %, 50 wt. %, 60 wt. %, 80 wt. %, or any range including any two of these values as endpoints, such as 20 wt. % to 80 wt. %, 25 wt. % to 60 wt. %, 30 wt. % to 50 wt. %, or 35 wt. % to 40 wt. %, wherein the weight percent is based on the total weight of the “wet” coating composition.

[0036] Binder resin may be present in the cured coating composition, in an amount from 35 wt.%, 55 wt.%, 70 wt.%, 75 wt.% to 80 wt.%, 85 wt.%, 90 wt.%, 98 wt. %, or any range including any two of these values as endpoints, such as 35 wt.% to 98 wt.%, 55 wt.% to 90 wt.%, 70 wt.% to 85 wt.%, or 75 wt.% to 80 wt.%, wherein the weight percent is based on the total weight of the “dry” coating composition.

[0037] Binder resin may be present in the cured coating composition, in a volume from 40 %, 60 %, 70 % to 80 %, 90 %, 98 %, or any range including any two of these values as endpoints, such as 40 % to 98 %, 60 % to 90 %, or 70 % to 80 %, wherein the volume percent is based on the total volume of the “dry” coating composition.

[0038] i. Polyamide Imide

[0039] The binder resin of the present disclosure may be a polymer binder resin comprising polyamide imide (PAI). Polyamide-imides (PAI) may be thermosetting or thermoplastic amorphous polymers and typically have exceptional mechanical, thermal and chemical resistant properties. Suitable polyamide-imides may include polyamide-imides produced by Solvay Specialty Polymers under the trademark Torlon. Polyamide-imide polymers may be formed from isocyanates and TMA (trimellic acid-anhydride) in N-methyl- 2-pyrrolidone (NMP). Polyamide-imides may possess desirable properties of bothpolyamides and polyimides, such as high strength, melt processibility, exceptional high heat capability, and broad chemical resistance. Polyamide-imide polymers can be processed into a wide variety of forms – from injection or compression molded parts and ingots – to coatings, films, fibers, and adhesives. Typically, these articles reach their maximum properties with a subsequent thermal cure process.

[0040] ii. Epoxy

[0041] The binder resin may be an epoxy resin. The epoxy resin may comprise a polymer including an epoxy group and exhibit mechanical properties as adhesives, plastics and coating materials. The binder resin may be an epoxy phenolic resin. Epoxy phenolic resins are phenolic resins modified at the phenolic hydroxyl group to include an epoxide functional group, increasing the ability for the resin to crosslink. Suitable epoxy resins may include EPON product lines from Resolution Products (e.g., Epon 828, bisphenol A- epichlorohydrin epoxy resin and / or blends of this resin with difunctional epoxide-reactive diluents such as neopentyl glycol diglycidyl ether, resorcinol diglycidyl ether, and cyclohexanedimethanol diglycidyl ether; Epon DPL862, bisphenol F-epichlorohydrin epoxy resin); EPALLOY product line from CVC Thermoset Specialties (e.g., EPALLOY 8250, epoxy novolac resin); araldite EPN 1139 by Ciba Geigy; and DEN432, DEN438, DEN439 and DEN440 by OlinTM. Suitable non-aromatic epoxy resins include hydrogenated cyclohexane dimethanol and diglycidyl ethers of hydrogenated bisphenol a type epoxy resins such as: EPON product lines from Resolution Products (e.g., EPON 1510, EPON 4080E, Heloxy 107, and EPON 1513, hydrogenated bisphenol a-epichlorohydrin epoxy resin); santolink LSE-120 from Monsanto; epodii 757 (cyclohexanedimethanol diglycidyl ether) by pacifiic Anchor; araldite XUGY358 and PY327 by Ciba Geigy; epirez 505 from Rhone- Poulene; aroflint 393 and 607 from Reichold; EPI-REZ from Momentive; epoxy resins from Kukdo; epoxy resins from Aditya Birla; and ERL4221 by Union Carbide.

[0042] iii. Silicone Polyester

[0043] Silicone polyester resins may be co-polymers prepared by polycondensation of a diol and a di-acid to which an alkoxy or hydroxy functional siloxane oligomer or monomer are grafted. Silicone polyester resins may be supplied in dry form or dissolved in a solvent, such as, but not limited to, methoxy propyl acetate, toluene, xylene, butyl acetate, ethyl acetate, and methyl isobutyl ketone. Suitable silicone polyesters may include Chempol 806- 1332, Silicoftal HTF, Silicoftal HTL, Silicoftal HTT, Silicoftal HTW3, Silicoftal Non-stick 60, SW weather XL, and Akzo Cream-A-star.

[0044] iv. Polyurethane

[0045] Polyurethane resins may be prepared by reacting a polyester polyol, polycarbonate polyol, polyether polyol or acrylic polyol with a polyisocyanate and an acid functional polyol (such as dimethylol propionic acid) such that the NCO / OH ratio is greater than 1:1 to generate an NCO functional prepolymer. The terminal isocyanates may then be reacted in one of a number of methods described below to generate terminal COOH groups. The acid groups introduced in the first stage of urethane preparation are considered to be internal COOH groups, while the acid groups introduced via reaction of the prepolymer NCO end groups are considered to be terminal COOH groups. The acid functional polyurethane polymers may be neutralized with amine and dispersed into water. Suitable polyurethane resins may include Desmolac from Covestro, GN-410 from Polyval, Sancure 2310 from Lubriol, Sancure 20072 from Lubriol, Aptalon 8300 from Lubriol, Aptalon M8120 from Lubriol, Hydran Wi from DIC, Hydran Ap from DIC, Hydran Cp from DIC, Vondic from DIC, RIMLINE from Huntsman, VITROX from Huntsman, and PU binder 1128.

[0046] B. Lubricating Component

[0047] Another component of the coating composition is a lubricating component. The lubricating component acts to reduce friction at the surface of the coating upon contact of the coated substrate with another component.

[0048] The lubricating component may comprise a wax and, optionally, a silicone resin.

[0049] The coating composition of the present disclosure may have a weight ratio of lubricating component to the total of dry binder resin and dry lubricant from 0.001, 0.005, 0.01, to 0.10, 0.25, 0.5 or any range including any two of these values as endpoints, such as 0.001 to 0.50, 0.005 to 0.25, or 0.01 to 0.10.

[0050] i. Wax

[0051] The coating composition provided by the present disclosure may comprise a weight percentage of wax, for example, from 0.05 wt. %, 0.5 wt. %, 1 wt. % to 2 wt. %, 5 wt. %, 10 wt. %, or any range including any two of these values as endpoints, such as 0.05 wt. % to 10 wt. %, 0.5 wt. % to 5 wt. %, or 1 wt. % to 2 wt. %, wherein the weight percent is based on the total weight of the “wet” coating composition.

[0052] The wax may be present in the cured coating composition, in an amount from 0.1 wt.%, 1 wt.%, 10 wt.% to 20 wt.%, 30 wt.%, 35 wt. %, or any range including any two of these values as endpoints, such as 0.1 wt.% to 35 wt.%, 1 wt.% to 30 wt.%, or 10 wt.% to 20wt.%, wherein the weight percent is based on the total weight of the “dry” coating composition.

[0053] The wax may be present in the cured coating composition, in a volume from 0.5 %, 5 %, 10 % to 20 %, 30 %, 45 %, or any range including any two of these values as endpoints, such as 0.5 % to 45 %, 5 % to 30 %, or 10 % to 20 %, wherein the volume percent is based on the total volume of the “dry” coating composition.

[0054] a. Carnauba Wax

[0055] Carnauba wax is a natural wax that comes from the leaves of the carnauba palm, a plate native to northeastern Brazil. Carnauba wax comprises of aliphatic esters, diesters, 4-hydroxycinnamic acid, w-hydroxycarboxylic acids, and fatty alcohols.

[0056] Carnauba wax may comprise particles having a median diameter, or D50, less than 15 µm, less than 12 µm, less than 8 µm, less than 6 µm, less than 4 µm, less than 2 µm, less than 1 µm, less than 0.5 µm, or less than 0.1 µm, as determined by dynamic light scattering measured through Mie scattering and Fraunhofer diffraction technique as per ISO 13320-1 practice.

[0057] b. Polyethylene Wax

[0058] Polyethylene wax is a low molecular weight synthetic wax made of ethylene monomer chains. Polyethylene wax may be synthesized in a variety of ways, such as the direct polymerization of ethylene. The molecular weight of polyethylene wax may fall in the range of 1,000-50,000 g / mol as measured by GPC (Gel Permeation Chromatography).

[0059] The lubricating component may comprise the powder form of polyethylene wax. Powder polyethylene wax may comprise particles having a median diameter, or D50, from 4 µm, 5 µm, 6 µm to 8 µm, 10 µm, 12 µm, or any range using any of the foregoing values as end points, such as 4 µm to 12 µm, 5 µm to 10 µm, or 6 µm to 8 µm, as measured by dynamic light scattering measured through Mie scattering and Fraunhofer diffraction technique as per ISO 13320-1.

[0060] c. Fischer-Tropsch Wax

[0061] Fischer-Tropsch wax is a synthetic wax produced by the polymerization of carbon monoxide and hydrogen. The branched chain of the Fischer Tropsch wax comprises straight alkanes and no double bonds.

[0062] The lubricating component may comprise the powder form of Fischer-Tropsch wax. Powder Fisch-Tropsch wax may comprise particles having a median diameter, or D50, from 1 µm, 2 µm, 4 µm to 6 µm, 8 µm, 10 µm, or any range using any of the foregoingvalues as end points, such as 1 µm to 10 µm, 2 µm to 8 µm, or 4 µm to 6 µm, as measured by dynamic light scattering measured through Mie scattering and Fraunhofer diffraction technique as per ISO 13320-1.

[0063] d. Polypropylene Wax

[0064] Polypropylene wax (PP wax) is a type of synthetic wax derived from polypropylene, a thermoplastic polymer. Polypropylene wax is typically produced through the polymerization of propylene monomers, resulting in a material with wax-like properties.

[0065] e. Polyamide Wax

[0066] The lubricating component may comprise a polyamide wax. Polyamide wax (PA wax) is a type of synthetic wax derived from polyamide resins. Polyamides are polymers with repeating amide linkages in their molecular structure. They are often used in various industries due to their excellent mechanical properties, chemical resistance, and thermal stability. Polyamide wax is typically produced through the polymerization of amide monomers, resulting in a solid or semi-solid material with a waxy texture.

[0067] iv. Silicone Resin

[0068] The coating composition may comprise at least one silicone resin. The silicone resin may include silsesquioxane polymers of the general formula: (C6H5SiO1.5)xwhere x is an integer greater than about 4.

[0069] The coating composition may comprise a total amount of silicone resin from 1 wt. %, 2 wt. %, 4 wt. % to 6 wt. %, 8 wt. %, 10 wt. %, or any range including any two of the forgoing values as endpoints, such as 1 wt. % to 10 wt. %, 2 wt. % to 8 wt. %, or 4 wt. % to 6 wt. %, wherein the weight percentage is based on the total weight of the “wet” coating composition.

[0070] After the coating is applied and cured, the silicone resin may be present in the coating composition in a total amount ranging from 15 wt. %, 20 wt.%, 25 wt.% to 30 wt.%, 35 wt.%, 40 wt. %, or any range including any two of the foregoing values as endpoints, such as 15 wt.% to 40 wt.%, 20 wt.% to 35 wt.%, or 25 wt.% to 30 wt.%, wherein the weight percent is based on the total weight of the “dry” coating composition.

[0071] The silicone resin may be present in the cured coating in a total amount ranging from 10 vol. %, 20 vol.%, 25 vol.% to 30 vol.%, 35 vol.%, 45 vol. %, or any range including any two of the foregoing values as endpoints, such as 10 vol.% to 45 vol.%, 20 vol.% to 35 vol.%, or 25 vol.% to 30 vol.%, wherein the volume percent is based on the total volume of the “dry” coating composition.

[0072] Suitable silsesquioxane polymers may comprise poly(alkylsilsesquioxane) and poly(aryl-alkylsilsesquioxane).

[0073] a. Poly(alkylsilsesquioxane)

[0074] A representative structure of poly(alkylsilsesquioxane) is shown in Formula I: R Rwherein R can be an alkyl substituent such as methyl, ethyl, propyl, butyl, octyl, etc.

[0075] Suitable poly(alkylsilsesquioxane) silicone resins may include poly(methylsilsesquioxane) as shown in Formula II.

[0076] Poly(alkylsilsesquioxane) used herein may be available in solid spherical beads form. The beads can be dispersed with other components of the coating composition. The size of the beads may be 1 µm, 2 µm, 4 µm to 6 µm, 8 µm, to 10 µm, or any range using any of the foregoing values as endpoints, such as 1 µm to 10 µm, 2 µm to 8 µm, or 4 µm to 6µm, as measured on a Coulter Counter Multisizer using Electrical Sensing Zone method or using similar particle size analyzer.

[0077] The poly(alkylsilsesquioxane) beads can be formed from the hydrolysis and precipitation of a respective silane monomer. The molecular weight of the poly(alkylsilsesquioxane) beads can be 2000 g / mol, 3000 g / mol, 4000 g / mol to 6000 g / mol, 8000 g / mol, 10,000 g / mol, or any range using the foregoing values as endpoints, such as 2000 g / mol to 10000 g / mol, 3000 g / mol to 8000 g / mol, or 4000 g / mol to 6000 g / mol. The molecular weight of poly(alkylsilsesquioxane) can be measured using GPC or other analytical techniques.

[0078] b. Poly(aryl-alkylsilsesquioxane)

[0079] A representative structure of poly(aryl-alkylsilsesquioxane) is shown in Formula III:wherein R can be an aryl substituent such as phenyl; and R’ can be an alkyl substituent such as methyl, ethyl, propyl, butyl, octyl, etc.

[0080] Suitable poly(aryl-alkylsilsesquioxane) silicone resins may include POSS- phenylpropyl.

[0081] The structure of the poly(aryl-alkylsilsesquioxane) may comprise of about 70% phenyl containing silicon atoms and about 30% propyl containing silicon atoms. As used herein, the poly(aryl-alkylsilsesquioxane) may be in solid or powder or flake form.

[0082] The powder can be formed from the hydrolysis and precipitation of a mixture of silane monomers. The molecular weight of poly(aryl-alkylsilsesquioxane) can be 1000g / mol, 1500 g / mol, 2000 g / mol to 3000 g / mol, 3500 g / mol, 4000 g / mol, or any range using any of the foregoing values as end points, such as 1000 g / mol to 4000 g / mol, 1500 g / mol to 3500 g / mol, or 2000 g / mol to 3000 g / mol, as measured by gel permeation chromatography (GPC) or other analytical techniques.

[0083] C. Solvent

[0084] The coating composition may include one or more solvents. Suitable solvents include water, alcohols such as C1-C8 alcohols including methanol, ethanol, isopropanol, and t-butanol, C2-C8 ketones including acetone, C2-C20 ethers including dipropylene glycol methyl ether and other protic or non-protic solvents like dimethylsulfoxide or N- methylpyrrolidone.

[0085] The solvent may be present in the composition in an amount from 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. % to 35 wt. %, 40 wt. %, 45 wt. %, 50 wt. %, or any value encompassed by these endpoints, such as 15 wt. % to 50 wt. %, 20 wt. % to 45 wt. %, 25 wt. % to 40 wt. %, or 30 wt. % to 35 wt. %, wherein the weight percent is based on the total weight of the “wet” coating composition.

[0086] D. Additives

[0087] Additives may be present in the coating composition of the present disclosure in addition to the components described above. These additives may comprise components to improve stability, applicability and aesthetics. Additives that may be included in the present coating composition may include dispersing aids, defoamers, thickeners, surface agents, tinting paste, and pigments.

[0088] The total amount of such additives within the coating composition may comprise from 0 wt. %, 5 wt. %, 10 wt. % to 20 wt. %, 30 wt. %, 40 wt. %, or any other range combination using these endpoints, such as 0 wt.% to 40 wt.%, 5 wt. % to 30 wt. %, or 10 wt. % to 20 wt. %, wherein the weight percentage is based on the total weight of the “wet” coating composition.

[0089] After the coating is applied and cured, the additives may be present in the coating composition in a total amount ranging from 0 wt. %, 2 wt.%, 4 wt.% to 6 wt.%, 8 wt.%, 10 wt. %, 15 wt.%, or any range including any two of these values as endpoints, such as 0 wt.% to 10 wt.%, 2 wt.% to 8 wt.%, or 4 wt.% to 6 wt.%, wherein the weight percent is based on the total weight of the “dry” coating composition.

[0090] III. Method of Coating a Rigid Substrate

[0091] The coating composition of the present disclosure may be applied to a rigid substrate such as an aluminum alloy or other metallic substrate, such as components of a solenoid, scrolls of a scroll compressor, fasteners, nuts, and bolts.

[0092] A. Application

[0093] To apply the coating composition of the present disclosure, the coating composition may be deposited onto the metallic substrate via a variety of methods. Methods of application may include coating by spraying, dipping, knife-on-air, knife-over-roller, pad printing, screen printing, dip spinning, rack spinning, tumble spraying, and electrostatic spraying.

[0094] i. Spraying

[0095] Spraying is another form of application that may be used to apply the coating composition of the present application. Spraying comprises using a spray of coating composition particles or droplets to deposit the coating composition onto a substrate. The substrate may be passed under a spray or otherwise exposed to a spray of the coating composition for a predetermined amount of time to deposit a desired amount of coating composition.

[0096] ii. Dipping

[0097] To coat the metallic substrate using a dipping process, the metallic substrate is dipped into a reservoir of the coating composition. The coated substrate is then removed from the reservoir and set out to cure.

[0098] iii. Knife-on-air

[0099] Knife-on-air or air knife coating is a process that applies a predetermined amount of coating composition to a substrate. The process comprises placing the substrate on a series of rollers that move the substrate under a mechanism that deposits the coating composition, such as a reservoir that drips the coating composition onto the substrate. An excess amount of coating composition may be deposited onto the substrate. To remove the excess coating, the coated substrate is passed under an air jet that blows the excess coating off of the substrate. The positioned angle of the air jet to the substrate and the velocity of the air are calculated such that a predetermined amount of coating composition remains on the substrate. The coating composition of the present disclosure may be applied to the metallic substrate using the knife-on-air method of application.

[0100] iv. Knife-over-roller

[0101] Another process to apply the coating composition of the present disclosure to the metallic substrate is knife-over-roller or gap coating. This process comprises placing the substrate on a series of rollers that pass under a mechanism that deposits a coating composition, similar to the knife-on-air process described above. The amount of coating composition that is deposited may be more than necessary to coat the substrate. To remove the excess coating, the substrate covered in coating is passed through a gap created between the substrate and a knife positioned above the substrate. The positioning of the knife is predetermined to scrape off coating in excess and leave only a desired amount of coating on the substrate as it passes through the gap.

[0102] B. Curing

[0103] Once the metallic substrate has been coated with the coating composition, the coating is cured or dried at temperatures from 170°C, 200°C, 210°C, to 220°C 230°C, 240°C, or any other range combination using these endpoints, such as 170°C to 240°C, 200°C to 230°C, or 210°C to 220°C. The coating composition may be cured at the temperatures previously listed from 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, or any other range combination using these endpoints, such as 20 min to 45 min, 25 min to 40 min, or 30 min to 35 min.

[0104] IV. Properties of Coating

[0105] The coating composition of the present disclosure exhibits a variety of properties including increased wear resistance, low coefficient of friction, and being fluoropolymer free.

[0106] A. Resistance to Wear and Coefficient of Friction

[0107] During the use of a substrate, like the scrolls of a scroll compressor, the coating composition cured to the substrate may experience wear due to the friction experienced by the coated substrate.

[0108] The coating composition described in the present disclosure increase the durability and wear resistance of a coated metallic substrate. This increased durability may increase the lifetime and use of the substrate and reduce the risk of failure.

[0109] B. Coefficient of Friction

[0110] The coefficient of friction (CoF) is a measure of the amount of friction existing between two surfaces. A low CoF indicates that the force required for sliding to occur is less than the force required when CoF is high. An increase in CoF means that there will be an increase in wear rate.

[0111] By measuring the CoF of a coated substrate, the wear resistance of a substrate can be estimated. Coatings that have a lower CoF will be more wear resistant than coatings with a higher CoF.

[0112] C. Perfluoroalkyl Substance and N-methyl pyrrolidone Free

[0113] Per- and polyfluoroalkyl substances (PFAS) are fluorine-containing chemical compounds including perfluoroalkyl acids (PFAAs) such as perfluorooctanoic acid (PFOA), and / or perfluorooctane sulfonate (PFOS).

[0114] With mounting regulation of PFAS, including fluoropolymers, there is a draw to have PFAS free coating compositions. The present coating compositions may lack PFAS, wherein the coating composition is essentially, substantially, or completely PFAS-free. By essentially PFAS-free it is meant that the coating compositions of the present disclosure comprises a total amount of perfluorinated and polyfluorinated alkyl compounds of 1 wt.% or less, based on a total weight of the coating composition and / or have a total content of PFAS less than 1 ppm, based on a total weight of the coating. By substantially PFAS-free it is meant that the coating compositions of the present disclosure comprises a total amount of perfluorinated and polyfluorinated alkyl compounds of 0.1 wt.% or less, based on a total weight of the coating composition and / or have a total content of PFAS less than 0.1 ppm, based on a total weight of the coating. By completely PFAS-free it is meant that the coating compositions of the present disclosure comprises a total amount of perfluorinated and polyfluorinated alkyl compounds of 0.01 wt.% or less, based on a total weight of the coating composition and / or have a total content of PFAS less than less than 0.01 ppm, based on a total weight of the coating.

[0115] N-methyl pyrroliodone (NMP) is an organic substance commonly used as a solvent.

[0116] With mounting regulation of NMP, there is a draw to have a NMP free coating composition. The present coating compositions may lack NMP, wherein the coating composition is essentially, substantially, or completely NMP-free. By essentially NMP -free it is meant that the coating compositions of the present disclosure comprises a total amount of perfluorinated and polyfluorinated alkyl compounds of 1 wt.% or less, based on a total weight of the coating composition and / or have a total content of NMP less than 1 ppm, based on a total weight of the coating. By substantially NMP -free it is meant that the coating compositions of the present disclosure comprises a total amount of perfluorinated and polyfluorinated alkyl compounds of 0.1 wt.% or less, based on a total weight of the coatingcomposition and / or have a total content of NMP less than 0.1 ppm, based on a total weight of the coating. By completely NMP -free it is meant that the coating compositions of the present disclosure comprises a total amount of perfluorinated and polyfluorinated alkyl compounds of 0.01 wt.% or less, based on a total weight of the coating composition and / or have a total content of NMP less than less than 0.01 ppm, based on a total weight of the coating.

[0117] V. Applications

[0118] The coating composition may be applied to any rigid substrate. Suitable substrates may include metallic substrates made of aluminum, aluminum alloys, steel, stainless steel or other metals and alloys. Suitable substrates may further include scrolls of a scroll compressor, contacting components of a solenoid, fasteners, nuts, bolts, or other metal substrates. The coating composition may impart increased wear resistance and lubrication during use of the coated substrate.

[0119] A scroll compressor may comprise two interleaving metal scrolls to pump / compress liquids and gasses. The two interleaving scrolls include a fixed scroll and orbiting scroll. The orbiting scroll orbits eccentrically within the fixed scroll without rotating, trapping and pumping / compressing pockets of fluid between the scrolls. As such, the cooperating surfaces of the scrolls, or scroll wraps, interface with each other, causing eventual wear with use. The coating composition can be applied and cured on the surfaces of the scroll wraps of a scroll compressor to increase the resistance to wear of the scrolls, thereby increasing the life of the scroll compressor.

[0120] Further, the coating composition may be applied and cured on a solenoid actuators / plungers. A solenoid is used to turn electrical energy into mechanical work. A solenoid may comprise a coil of wire, a housing, and a plunger. When electrical current is applied to the solenoid, a magnetic field forms around the coil, drawing the plunger into the coil. The electrical current may then be turned off to move the plunger back to the starting position. Movement of the plunger during use of the solenoid may cause wear and tear. However, a solenoid plunger coated in the coating composition may experience an increase in resistance to wear, thereby increasing the life of the solenoid. EXAMPLES

[0121] Aspects of the present disclosure are further illustrated by reference to the following examples. It will be apparent to those skilled in the art that many modifications,both to materials, and methods, may be practiced without departing from the scope of the disclosure.

[0122] Compositions were formulated as described below according to the coating compositions of the present disclosure. The coating compositions were applied to a rigid substrate and the properties of the coatings were tested to yield the following results. Friction Testing Methods

[0123] The coating compositions were tested using two friction test methods, set forth below.

[0124] Method 1

[0125] An aluminum pin and disk were each pre-treated with a gritblast (AIO, 120 mesh). The coating composition was then applied to the pin and disk by HVLP gravity fed hand spray application. After application, the coated pin and disk were first flashed at 150oC for 15 min and then cured at 240oC for 40 minutes. The dry film thickness was 15-30 microns as determined using an electronic gauge.

[0126] The coated aluminum pin and disk were tested using a Bruker tribometer UMT-3 according to a pin and disk ASTM G99 wear test at a linear RPM of 4.98 m / s. The reported number of cycles (or time) until the coefficient of friction was greater than 0.5 was recorded. Each test was repeated 2-3 times and the average number of cycles was reported as a mean average.

[0127] Method 2

[0128] A steel disk and ball were used to test the wear resistance of the coating using the following method.

[0129] The steel disk was pre-treated with a gritblast (AIO, 120 mesh). The coating composition was then applied to the disk by HVLP gravity fed hand spray application. After application, the coated disk was first flashed at 150oC for 15 min and then cured at 240oC for 40 minutes. The dry film thickness was 15-30 microns as determined using an electronic gauge.

[0130] The ball and coated disk were then tested using a Bruker tribometer UMT-3 according to a ball on disk ASTM G99 procedure wear test protocol.

[0131] The steel ball had a diameter of 12.7 mm. The arc length was 2 mm and the frequency was 5 Hz. The test was run until the coefficient of friction was greater than 0.75.Each test was repeated 3-4 times and reported as a mean average. The coefficient of friction trend and visible track wear was evaluated.

[0132] Method 3

[0133] A steel disk, a 2 inch by 2 inch steel panel, and a steel pin were cleaned using isopropanol or acetone. The disk, panel, and pin were pre-treated with a gritblast (alumina 120 mesh). Before application of each coating composition, the coating composition was mixed on an air motor and a solvent 99B (NMP / Xylene:2 / 1) was added to adjust the viscosity as measured using a Zahn #2 cup. The solvent 99B was added in 2% increments until the coating compositions achieved a viscosity of 30 to 45 seconds in the Zahn #2 cup. The materials were then mixed for an additional 10 minutes and filled into a siphon spray vessel.

[0134] The coating compositions were applied to the pin, panel, and disk by hand spray application. After application, the coated pin, panel, and disk were cured at 176oC for 30 minutes. The dry film thickness of each coating was 15-20 µm as determined using an electronic gauge.

[0135] The coated disk, panel, and pin were tested using a Bruker tribometer UMT-3. The pin indenter has a diameter of 6.35 mm. The radius of the wear track is 17 mm while the testing load is 34.5 N with a speed of 2800 rpm.

[0136] The test was run between the pin-disk and the pin-panel until the coefficient of friction was greater than 0.5 or sparks were generated. The test was conducted at room temperature (20oC) and 150oC. The coefficient of friction trend and visible track wear was evaluated. Example 1A: Preparation of Coating Compositions

[0137] Comparative PTFE coating composition 1 was prepared according to the Table 1 below.

[0138] All components were combined using high shear mixing. Table 1: Comparative Coating Composition 1 Formulation Component / Description Wet Wt. % Formulation Dry Wt. % Dry Vol. %Component / Description Wet Wt. % Formulation Solids by Wt. Dry Wt. % Dry Vol. % N M th l 2 P li [low.

[0140] All components were combined using high shear mixing. The lubricant was mixed using a speed mixer at 1200 RPM for 45 minutes. The temperature during combination was kept below 40oC for stability of the PAI resin. Table 2: Inventive Coating 1 Formulation (1% dry vol. Carnauba wax) Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. % S lid b WtTable 3: Inventive Coating 2 Formulation (5% dry vol. Carnauba wax) Formulation Component / Description Wet Wt % Dry Wt % Dry Vol %Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. % Solids by Wt.. Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. % S lid b WtTable 5: Inventive Coating 4 Formulation (20% dry vol. Carnauba wax) Formulation Component / Description Wet Wt % Dry Wt % Dry Vol %Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. % Solids by Wt.

[0141] Each of inventive coatings 1-4 and the comparative coating 1 were applied to a substrate using Method 1, described above. The results are set forth in FIGS.1 and 2. As shown in FIGS.1 and 2, inventive coatings 2, 3, and 4 exhibited improved properties over comparative coating 1. Inventive coating 2 showed a lower CoF than the comparative coating. While, as seen in FIG.2, inventive coatings 3 and 4 showed a significantly lower CoF than the comparative coating. Example 2A: Preparation of Coating Compositions

[0142] Comparative PTFE coating composition 2 was prepared according to the Table 6 below.

[0143] All components were combined using high shear mixing. The lubricant was mixed with a speed mixer at 1200 RPM for 45 minutes. Table 6: Comparative Coating Composition 2 Formulation Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. %Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. % Solids by Wt. [

[0145] All components were combined using a speed mixer at 1200 RPM for 45 minutes. No mechanical griding was performed. The temperature during combination was kept below 40oC for stability of the PAI resin. Table 7: Inventive Coating 5 Formulation (8-12 dry vol. Carnauba wax with NEP) Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. % li WtExample 2B: Testing Coating Compositions Using Method 2

[0146] Comparative coating 2 and Inventive coatings 3 and 5 were applied to a substrate using Method 1, described above. The results are set forth in FIG.3. As shown in FIG. 3, inventive coatings 3 and 5 exhibited improved properties over comparative coating 2. Inventive coatings 3 and 5 both had a lower CoF than comparative coating 2.

[0147] Wherein particular examples of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variationsof the details of the present invention may be made without departing from the invention as defined in the appended claims. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims. Example 3A: Preparation of Coating Compositions

[0148] Comparative PTFE coating composition 1 was prepared according to the Tables 8-10 below.

[0149] All components were combined using high shear mixing. Table 8: Comparative Coating Composition 3 Formulation Component / Description Wet Wt. % Formulation Solids by Wt. Dry Wt. % Dry Vol. %

[0150] Inventive (Inv.) coating compositions 6-20 were prepared according to the Tables 11-25 below.

[0151] All components were combined and mixed using high shear mixing under air. The temperature during combination was kept below 40oC for stability of the PAI resin.Table 11: Inventive Coating 6 Formulation Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. % S lid b Wtg Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. %Table 13: Inventive Coating 8 Formulation Formulation Com onent / Descri tion Wet Wt % Dr Wt % Dr Vol %Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. % Solids by Wt.Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. % S lid b WtTable 15: Inventive Coating 10 Formulation Wet Wt. Formulation Dry Vol. Component / Description Dry Wt %Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. % % Solids by Wt. %Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. % % Solids b Wt %Table 17: Inventive Coating 12 Formulation Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. %Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. % % Solids by Wt. %Formulation Component / Description Wet Wt. % Dry Wt. % Dry Vol. %Table 19: Inventive Coating 14 Formulation Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. %Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. % % Solids by Wt. %Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. % % Solids by Wt. %Table 21: Inventive Coating 16 Formulation Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. %Table 22: Inventive Coating 17 Formulation Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. % % Solids by Wt. %g Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. %Table 24: Inventive Coating 19 Formulation Wet Wt. Formulation Dry Vol. Com onent / Descri tion Dr Wt %Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. % % Solids by Wt. %Wet Wt. Formulation Dry Vol. Component / Description Dry Wt. % % S lid b Wt %Table 26: Inventive Coating 21 Formulation Component / Description Wet Wt. Formulation Solids Dry Wt. Dry Vol.Component / Description Wet Wt. Formulation Solids Dry Wt. Dry Vol. % by Wt. % %Component / Description Wet Wt. Formulation Solids Dry Wt. Dry Vol. % by Wt. % %Example 3B: Testing Coating Compositions Using Method 3

[0152] Comparative coatings 3-5 and inventive coatings 6-20 were applied to a substrate using Method 3, described above. The results are set forth in Tables 26, 27 and 28 and FIGS.4-6. Table 28: Testing Results for Comp. 3 and Inv.6-11 Comp. Inv.6 Inv. 7 Inv. 8 Inv. 9 Inv. 10 Inv.11Comp. 3 Inv.6 Inv.7 Inv.8 Inv.9 Inv.10 Inv.11 Pl Mthlil i 1 1 06 72Comp.3 Inv.13 Inv.14 Inv.12 Inv.15 PTFE 15 6abe 30: es ng esu s or Comp.3 and nv. 6-0 Comp.3 Inv.16 Inv.17 Inv.18 Inv.19 Inv.20 PTFE 15 53Table 31: Testing Results for Inv.21-22 Inv.21 Inv.22Inv.21 Inv.22 Polyamide wax 5

[0153] The results are set forth in FIG.4 show that inventive coatings 7, 10, and 11 exhibited improved properties over comparative coating 3. Inventive coating 11 showed a significantly lower CoF than comparative coating 3.

[0154] In FIG.5, inventive coatings 13, 12, and 15 all showed significantly lower CoF than comparative coating 3.

[0155] And finally, in FIG.6, inventive coatings 17, 19, and 20 all showed a lower CoF than comparative coating 5. Inventive coating 19 showed a significant improvement in properties over comparative coating 3. Prophetic Example 4: Coating Compositions with Epoxy Binder Resin

[0156] Inventive coatings 6-20 are prepared using the same formulations listed in Example 3A except instead of using PAI as a binder resin, epoxy resin was used as the binder resin.

[0157] The inventive coatings using epoxy binder resin and comparative coating 3 are tested using method 3. The results show that the inventive coatings with epoxy binder resin have improved properties over comparative coating 3. Prophetic Example 5: Coating Compositions with Silicone Polyester Binder Resin

[0158] Inventive coatings 6-20 are prepared using the same formulations listed in Example 3A except instead of using PAI as a binder resin, silicone polyester resin was used as the binder resin.

[0159] The inventive coatings using silicone polyester binder resin and comparative coating 3 are tested using method 3. The results show that the inventive coatings with silicone polyester binder resin have improved properties over comparative coating 3.Prophetic Example 6: Coating Compositions with Polyurethane Binder Resin

[0160] Inventive coatings 6-20 are prepared using the same formulations listed in Example 3A except instead of using PAI as a binder resin, polyurethane was used as the binder resin.

[0161] The inventive coatings using polyurethane binder resin and comparative coating 3 are tested using method 3. The results show that the inventive coatings with polyurethane binder resin have improved properties over comparative coating 3.

Claims

CLAIMS What is claimed is:

1. A coating composition for a rigid substrate, comprising: a binder resin; a lubricating component comprising a wax; and a solvent.

2. The coating composition of claim 1, wherein the binder resin is selected from polyamide imide, epoxy, silicone polyester, and polyurethane resin.

3. The coating composition of either claim 1 or claim 2, wherein the lubricating component further comprises a silicone resin.

4. The coating composition of claim 3, wherein the silicone resin is selected from poly(aryl-alkylsilsesquioxane) and poly(alkylsilsesquioxane).

5. The coating composition of any one of claims 1-4, wherein the wax has a melting point from 70oC to 140oC, as determined by Differential Scanning Calorimetry (DSC) according to ASTM E794 – 06(2018) 6. The coating composition of any one of claims 1-5, wherein the wax is at least one of a carnauba wax, a polyethylene wax, polypropylene wax, polyamide wax, and a Fischer- Tropsch wax.

7. The coating composition of any one of claims 1-6, wherein the binder resin comprises from 20 to 80 wt.% of the coating composition, based on a total wet weight of the coating composition.

8. The coating composition of any one of claims 1-7, wherein the binder resin comprises from 35 to 78 wt.% of the coating composition, based on a total wet weight of the coating composition.

9. The coating composition of any one of claims 1-8, wherein the wax comprises from 0.05 to 10 wt.% of the coating composition, based on a total wet weight of the coating composition.

10. The coating composition of any one of claims 1-9, wherein the silicone resin comprises 1 to 10 wt. % of the coating composition, based on the total wet weight of the coating composition.

11. The coating composition of any one of claims 1-10, wherein the wax comprises particles of wax having an average particle size (D50) of less than 12 microns, as determined by dynamic light scattering ISO 13320-1.

12. The coating composition of any one of claims 1-11, comprising a total amount of perfluoroalkyl substances (PFAS) of 1 ppm or less, based on a total weight of the coating composition.

13. The coating composition of any one of claims 1-12, comprising a total amount of N- methyl pyrrolidone (NMP) of 1 ppm or less, based on a total weight of the coating composition.

14. A method of coating a rigid substrate, comprising: applying the coating composition of any one of claims 1-13 to the rigid substrate; and curing the coating composition at a temperature from 170 to 240oC.

15. A coated rigid substrate, comprising: a rigid substrate; and a coating on the rigid substrate, comprising: a binder resin; and a lubricating component comprising a wax.

16. The coated rigid substrate of claim 15, wherein the binder resin is selected from polyamide imide, epoxy, silicone polyester, and polyurethane resin.

17. The coated rigid substrate of either claim 15 or claim 16, wherein the lubricating component further comprises a silicone resin.

18. The coated rigid substrate of claim 17, wherein the silicone resin is selected from poly(aryl-alkylsilsesquioxane) and poly(alkylsilsesquioxane).

19. The coated rigid substrate of any one of claims 15-18, wherein the wax has a melting point from 70oC to 140oC, as determined by ASTM D87.

20. The coated rigid substrate of any one of claims 15-19, wherein the wax is at least one of a carnauba wax, a polyethylene wax, polypropylene wax, polyamide wax, and a Fischer- Tropsch wax.

21. The coated rigid substrate of any one of claims 15-20, wherein the binder resin comprises from 35 to 98 wt.% of the coating composition, based on a total dry weight of the coating composition.

22. The coated rigid substrate of any one of claims 15-21, wherein the binder resin comprises from 40 to 98 vol % of the coating composition, based on a total dry volume of the coating composition.

23. The coated rigid substrate of any one of claims 15-22, wherein the wax comprises from 0.1 to 35 wt.% of the coating composition, based on a total dry weight of the coating composition.

24. The coated rigid substrate of any one of claims 15-23, wherein the wax comprises from 0.5 to 45 vol. % of the coating composition, based on a total dry volume of the coating composition.

25. The coated rigid substrate of either claim 17 or claim 18, wherein the silicone resin comprises 15 to 40 wt. % of the coating composition, based on the total dry weight of the coating composition.

26. The coated rigid substrate of either claim 17 or claim 18, wherein the silicone resin comprises 10-45 vol. % of the coating composition, based on the total dry volume of the coating composition.

27. The coated rigid substrate of any of claims 15-26, wherein the substrate is a metallic material comprising aluminum, steel, other metallic alloys, or combinations of the foregoing.

28. The coated rigid substrate of any one of claims 15-27, wherein the substrate is a fixed or orbiting scroll component of a scroll compressor.

29. The coated rigid substrate of any one of claims 15-28, wherein the substrate is a solenoid plunger.

30. The coated rigid substrate of any one of claims 15-29, wherein the substrate is one of a fastener, nut, and bolt 31. The coated rigid substrate of any one of claims 15-30, wherein the wax comprises particles of wax having an average particle size (D50) of less than 12 microns, as determined by dynamic light scattering ISO 13320-1.

32. The coated rigid substrate of any one of claims 15-31, comprising a total amount of perfluoroalkyl substances (PFAS) of 1 ppm or less, based on a total weight of the coating composition.

33. The coated rigid substrate of any one of claims 15-32, comprising a total amount of N-methyl pyrrolidone (NMP) of 1 ppm or less, based on a total weight of the coating composition.

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