WO2026005996A1 - Primer compositions for high performance rubber to substrate bonding - Google Patents

Abstract

Environmentally friendly primer compositions for rubber to substrate bonding. The primers can include film forming polymers, benzoxazine (BZX) resins, and fillers, in either a solvent-based formulation or an aqueous-based formulation. Some primer compositions can further include a co-resin such as bismaleimide (BMI). Methods of bonding components, including rubber to a substrate, and subsequent bonded assemblies are also provided.

Description

Docket No. 1770.0148WO PRIMER COMPOSITIONS FOR HIGH PERFORMANCE RUBBER TO SUBSTRATE BONDING CROSS REFERENCE TO RELATED APPLICATION 5 The disclosure herein claims priority to United States Provisional Patent Application Serial No. 63/663,389, filed June 24, 2024, the disclosure of which is incorporated herein by reference in its entirety. TECHNICAL FIELD The disclosure herein relates to primer compositions for high performance 10 rubber to substrate bonding. BACKGROUND Existing aqueous primer technology is based on traditional phenolic chemistry, many of which provide excellent adhesion to metal substrates. However, there is a desire to move away from the use of traditional phenolics, as 15 well as solvents which are needed to stabilize the phenolic resins used in solvent primers. Moreover, existing aqueous technology is relatively expensive because of the raw materials used for formulations. Thus, there remains a need for improved aqueous and solvent primer technologies that are based on environmentally friendly components. There is also 20 a need for such improved primers to be cost-efficient to manufacture and have excellent shelf-life stability and desirable performance characteristics. Such needs are fulfilled by the presently disclosed subject matter. SUMMARY This summary lists several embodiments of the presently disclosed subject 25 matter, and in many cases lists variations and permutations of these embodiments. This summary is merely an example of the numerous and varied embodiments. Mention of one or more representative features of a given embodiment is likewise for purposes of example. Such an embodiment can typically exist with or without the feature(s) mentioned; likewise, those features can be applied to other 30 embodiments of the presently disclosed subject matter, whether listed in this 1 Docket No. 1770.0148WO summary or not. To avoid excessive repetition, this summary does not list or suggest all possible combinations of such features. Primer compositions for rubber to substrate bonding are disclosed herein. The primer compositions comprise a film forming polymer, wherein the film 5 forming polymer comprises a chlorinated and/or non-chlorinated film former; a resin, optionally a benzoxazine (BZX) resin; a filler; and a carrier, wherein the carrier is a solvent carrier or an aqueous carrier. In some embodiments, such primer compositions comprise a co-resin, optionally a bismaleimide (BMI). In some embodiments, the primer compositions further comprise one or 10 more of: a catalyst; a surfactant; an acid scavenger; a rheological agent; a corrosion inhibitor; a coloring agent; and/or combinations thereof. In some embodiments, the primer compositions further comprise a rubber curative; an inorganic additive, optionally wherein the inorganic additive is selected from ceramic particles, silica, metal oxide powders, natural and synthetic 15 clays, glass beads, boron nitride, zinc oxide, magnesium oxide, and carbon black; and/or nanomaterials. In some embodiments, the resin comprises BZX at a concentration of about 3.0% to about 7.0% (i.e., about 3.0 wt% to about 7.0 wt% based on the total weight of the primer composition) and the co-resin comprises BMI at a concentration of 20 about 0.5% to about 4%. In some embodiments, the catalyst is at a concentration of about 0.1% to about 3%; wherein the surfactant is at a concentration of about 0.1% to about 1%; wherein the acid scavenger is at a concentration of about 2% to about 7%; wherein the rheological agent is at a concentration of about 0.1% to about 5%; wherein the corrosion inhibitor is at a concentration of about 0.1% to 25 about 2%; wherein the filler is at a concentration of about 2% to about 5%; wherein the coloring agent is at a concentration of about 0.1% to about 1%. In some embodiments, the primer composition is aqueous-based and the primer composition comprises an aqueous carrier, optionally wherein the aqueous carrier is about 65% to about 85% of the primer composition. In some 30 embodiments, the primer composition is solvent-based and the primer 2 Docket No. 1770.0148WO composition comprises a solvent carrier, optionally wherein the solvent carrier is about 65% to about 85% of the primer composition. In some embodiments, the primer composition is soluble in non-carcinogenic, non-mutagenic and non- reprotoxic chemical (non-CMR) solvents. 5 In some embodiments, the primer compositions comprise (a) about 7.5% film forming polymer, optionally a chlorinated polyethylene; (b) about 5.0% BZX resin; (c) about 1.25% catalyst for cure control, optionally a polyphenol; (d) about 4.25% acid scavenger, optionally zinc oxide; (e) about 1.25% rheological agent, optionally silica; (f) about 5.0% filler, optionally titanium oxide; (g) about 0.75% 10 coloring agent, optionally carbon black; and (h) about 75.0% solvent, optionally xylene. In some embodiments, the primer compositions comprise (a) about 5.7% film forming polymer, optionally a chlorinated polyvinylchloride; (b) about 3.7% BZX resin; (c) about 1.0% catalyst for cure control, optionally a polyphenol; (d) 15 about 3.2% acid scavenger, optionally zinc oxide; (e) about 1.0% rheological agent, optionally silica; (f) about 3.8% filler, optionally titanium oxide; (g) about 0.6% coloring agent, optionally carbon black; and (h) about 81.0% solvent, optionally cyclohexanone. In some embodiments, the primer compositions comprise (a) about 2.75% 20 film forming polymer, optionally polychloroprene; (b) about 6.5% BZX resin; (c) about 1.25% catalyst for cure control, optionally a polyphenol; (d) about 6.25% acid scavenger, optionally zinc oxide; (e) about 1.25% rheological agent, optionally silica; (f) about 5.5% filler, optionally titanium oxide; (g) about 1.75% coloring agent, optionally carbon black; (h) about 0.75% corrosion inhibitor; and 25 (i) about 74.0% solvent, optionally xylene. In some embodiments, the primer compositions comprise (a) about 7.5% film forming polymer, optionally polyetherimide; (b) about 5.0% BZX resin; (c) about 1.25% catalyst for cure control, optionally a polyphenol; (d) about 4.25% acid scavenger, optionally zinc oxide; (e) about 1.25% rheological agent, 30 optionally silica; (f) about 5.0% filler, optionally titanium oxide; (g) about 0.27% 3 Docket No. 1770.0148WO coloring agent, optionally carbon black; and (h) about 75.0% solvent, optionally 60% methyl isobutyl ketone (MIBK) and 15% xylene. In some embodiments, the primer compositions comprise (a) about 7.5% film forming polymer, optionally chlorinated polyethylene; (b) about 4.5% BZX 5 resin; (c) about 2.4% co-resin, optionally bismaleimide (BMI); (d) about 1.5% catalyst for cure control, optionally a polyphenol; (e) about 6.0% acid scavenger, optionally zinc oxide; (f) about 1.5% rheological agent, optionally silica; (g) about 6.0% filler, optionally titanium oxide; (h) about 0.6% coloring agent, optionally carbon black; and (i) about 70.0% solvent, optionally 42% MIBK and 10 28% xylene. In some embodiments, the primer compositions comprise (a) about 7.5% film forming polymer, optionally chlorinated polyethylene; (b) about 4.5% BZX resin; (c) about 0.5% co-resin, optionally allyl-BZX; (d) about 1.25% catalyst for cure control, optionally a polyphenol; (e) about 4.25% acid scavenger, optionally 15 zinc oxide; (f) about 1.25% rheological agent, optionally treated silica; (g) about 5.0% filler, optionally titanium oxide; (h) about 0.75% coloring agent, optionally carbon black; and (i) about 75.0% solvent, optionally xylene. In some embodiments, the primer compositions comprise (a) about 3.0% film forming polymer, optionally carboxylated styrene-butadiene rubber; (b) 20 about 4.75% BZX resin; (c) about 0.5% surfactant, optionally acrylic co-polymer salt; (d) about 1.33% dispersing agent, optionally sodium lignosulfonate; (e) about 1.25% catalyst for cure control, optionally a polyphenol; (f) about 5.3% acid scavenger, optionally zinc oxide; (g) about 1.6% rheological agent, optionally untreated silica; (h) about 1.52% filler, optionally titanium oxide; (i) 25 about 0.75% coloring agent, optionally carbon black; and (j) about 80.0% aqueous solvent, optionally deionized water. These and other objects are achieved in whole or in part by the presently disclosed subject matter. Other objects and advantages of the presently disclosed subject matter will become apparent to those skilled in the art after a study of the 30 following description, examples, and drawings. 4 Docket No. 1770.0148WO BRIEF DESCRIPTION OF THE DRAWINGS The presently disclosed subject matter can be better understood by referring to the following, example figure. The components in the figure are not necessarily to scale, emphasis instead being placed upon illustrating the principles 5 of the presently disclosed subject matter (often schematically). In the figure, like reference numerals designate corresponding parts throughout the different views. A further understanding of the presently disclosed subject matter can be obtained by reference to an embodiment set forth in the illustrations of the accompanying drawing. Although the illustrated embodiment is merely for purposes of example 10 of systems for carrying out the presently disclosed subject matter, both the organization and method of operation of the presently disclosed subject matter, in general, together with further objectives and advantages thereof, may be more easily understood by reference to the drawings and the following description. The drawing is not intended to limit the scope of this presently disclosed subject 15 matter, which is set forth with particularity in the claims as appended or as subsequently amended, but merely to clarify and provide examples of the presently disclosed subject matter. FIG. 1 is a schematic illustrating types of failures and failure points in adhesive to metal or adhesive to substrate bonding in accordance with the 20 presently disclosed subject matter. Fig.2. is a graphical depiction of data from the testing of primary bonding of solvent-based benzoxazine primer compositions containing: benzoxazine bismaleimide, and chlorinated polyethylene (BZX/BMI HPE2200); benzoxazine and chlorinated polyethylene (BZX HPE2200); benzoxazine and chlorinated 25 polyvinyl chloride (BZX CPVC_H829F), or benzoxazine and polyetherimide (BZX PEI1000) on coupons using an overcoat adhesive sold under the tradename CHEMLOK® 6125, bonding at 275°F (135°C) and 320°F (160°C). For comparison, data is shown for primary bonding of a control non-BZX-based primer (CH 205). 30 FIG. 3 is a graphical depiction of data from performance testing of chlorinated polyethylene (HPE2200) and chlorinated polyvinyl chloride (CPVC) as film formers in benzoxazine (BZX) primers using an overcoat adhesive sold under the tradename CHEMLOK® 6411, where a primer comprising HPE2200 5 Docket No. 1770.0148WO and BZX (HPE2200-BZX) was aged at 50°C for 5 weeks for performance consistency. For comparison, data is shown for primary bonding of a control non- BZX-based primer (CH 205). FIG. 4 is a graphical depiction of data from performance testing of 5 chlorinated polyethylene (HPE2200) as a film former and bismaleimide (BMI) as a co-resin in a benzoxazine (BZX) primer using an overcoat adhesive sold under the tradename CHEMLOK® 6125. For comparison, data is shown for primary bonding of a control non-BZX-based primer (CH 205). FIG. 5 is a graphical depiction of data from performance testing of a 10 chlorinated polyvinylchloride (CPVC) as a film former in a benzoxazine (BZX) primer using an overcoat adhesive sold under the tradename CHEMLOK® 6125. For comparison, data is shown for primary bonding of a control non-BZX-based primer (205). FIG.6 is a graphical depiction of data from testing of the use of an example 15 benzoxazine aqueous primer (referred to as “110-1”) with aqueous adhesives sold under the tradenames CHEMLOK® 8212 and CHEMLOK® 8560-1. The data shows 0, 2, and 4 minute (0’, 2’, and 4’) primary bonding prebake resistance percentages on coupons and average peak loads. An aqueous primer sold under the tradename CHEMLOK® 8008 was used as a control. 20 FIG. 7 is a graphical depiction of data from testing of the use of a benzoxazine aqueous primer (referred to as “110-1”) with aqueous adhesives sold under the tradenames CHEMLOK® 8212 and CHEMLOK® 8560-1. The data shows primary bonding and 24-hour boiling water data. An aqueous primer sold under the tradename CHEMLOK® 8008 was used as a control. 25 DETAILED DESCRIPTION The presently disclosed subject matter now will be described more fully hereinafter, in which some, but not all embodiments of the presently disclosed subject matter are described. Indeed, the presently disclosed subject matter can 30 be embodied in many different forms and should not be construed as limited to 6 Docket No. 1770.0148WO the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. I. Definitions The terminology used herein is for the purpose of describing particular 5 embodiments only and is not intended to be limiting of the presently disclosed subject matter. While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter. 10 All technical and scientific terms used herein, unless otherwise defined below, are intended to have the same meaning as commonly understood by one of ordinary skill in the art. References to techniques employed herein are intended to refer to the techniques as commonly understood in the art, including variations on those techniques or substitutions of equivalent techniques that would be 15 apparent to one of skill in the art. While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter. In describing the presently disclosed subject matter, it will be understood that a number of techniques and steps are disclosed. Each of these has individual 20 benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques. Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the 25 understanding that such combinations are entirely within the scope of the invention and the claims. Following long-standing patent law convention, the terms “a”, “an”, and “the” refer to “one or more” when used in this application, including the claims. 7 Docket No. 1770.0148WO Thus, for example, reference to "a resin" includes a plurality of such resins, and so forth. Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims 5 are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter. 10 As used herein, the term “about,” when referring to a value or to an amount of a composition, dose, sequence identity (e.g., when comparing two or more nucleotide or amino acid sequences), mass, weight, temperature, time, volume, concentration, percentage, etc., is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in 15 some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods or employ the disclosed compositions. The term “comprising”, which is synonymous with “including” “containing” or “characterized by” is inclusive or open-ended and does not 20 exclude additional, unrecited elements or method steps. “Comprising” is a term of art used in claim language which means that the named elements are essential, but other elements can be added and still form a construct within the scope of the claim. As used herein, the phrase “consisting of” excludes any element, step, or 25 ingredient not specified in the claim. When the phrase “consists of” appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole. 8 Docket No. 1770.0148WO As used herein, the phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter. With respect to the terms “comprising”, “consisting of”, and “consisting 5 essentially of”, where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms. As used herein, the term “and/or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for 10 example, the phrase “A, B, C, and/or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D. As used herein the term “alkyl” refers to C1-24 inclusive, linear (i.e., "straight-chain"), branched, or cyclic, saturated or at least partially and in some cases fully unsaturated (i.e., alkenyl and alkynyl) hydrocarbon chains, including for 15 example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, ethenyl, propenyl, butenyl, pentenyl, hexenyl, octenyl, butadienyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, and allenyl groups. "Branched" refers to an alkyl group in which a lower alkyl group, such as methyl, ethyl, or propyl, is attached to a linear alkyl chain. "Lower alkyl" refers to an alkyl group having 1 to about 8 20 carbon atoms (i.e., a C1-8 alkyl), e.g., 1, 2, 3, 4, 5, 6, 7, or 8 carbon atoms. "Higher alkyl" refers to an alkyl group having about 10 to about 24 carbon atoms, e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24 carbon atoms. In certain embodiments, "alkyl" refers, in particular, to C1-8 straight-chain alkyls. In other embodiments, “alkyl” refers, in particular, to C_1-8 branched-chain alkyls. 25 Alkyl groups can optionally be substituted (a “substituted alkyl”) with one or more alkyl group substituents, which can be the same or different. The term "alkyl group substituent" includes but is not limited to alkyl, substituted alkyl, halo, arylamino, acyl, hydroxyl, aryloxyl, alkoxyl, alkylthio, arylthio, aralkyloxyl, aralkylthio, carboxyl, alkoxycarbonyl, oxo, and cycloalkyl. In some embodiments, 30 there can be optionally inserted along the alkyl chain one or more oxygen, sulfur or 9 Docket No. 1770.0148WO substituted or unsubstituted nitrogen atoms, wherein the nitrogen substituent is hydrogen, lower alkyl (also referred to herein as “alkylaminoalkyl”), or aryl. Thus, as used herein, the term "substituted alkyl" includes alkyl groups, as defined herein, in which one or more atoms or functional groups of the alkyl group 5 are replaced with another atom or functional group, including for example, alkyl, substituted alkyl, halogen, aryl, substituted aryl, alkoxyl, hydroxyl isocyanate, carboxyl, phosphate, anhydride nitro, amino, alkylamino, dialkylamino, sulfate, mercapto, glycidyl, acrylate, methacrylate, siloxy, silanol, hydride, and vinyl. "Alkoxyl" refers to an alkyl–O– group wherein alkyl is as previously 10 described. The term "alkoxyl" as used herein can refer to, for example, methoxyl, ethoxyl, propoxyl, isopropoxyl, butoxyl, t-butoxyl, and pentoxyl. The terms “alkoxy” and “oxyalkyl” can be used interchangably with “alkoxyl”. The term “aryl” as used herein refers to an aromatic moiety that can be a single aromatic ring, or multiple aromatic rings that are fused together, linked 15 covalently, or linked to a common group, such as, but not limited to, a methylene or ethylene moiety. The common linking group can also be a carbonyl, as in benzophenone, or oxygen, as in diphenylether, or nitrogen, as in diphenylamine. The term “aryl” encompasses heterocyclic aromatic compounds. The aromatic ring(s) can comprise phenyl, naphthyl, biphenyl, diphenylether, diphenylamine, 20 and benzophenone, among others. In particular, the term “aryl” means a cyclic aromatic comprising about 5 to about 10 carbon atoms, e.g., 5, 6, 7, 8, 9, or 10 carbon atoms, and including 5- and 6-membered hydrocarbon and heterocyclic aromatic rings. The aryl group can be optionally substituted (a “substituted aryl”) with one 25 or more aryl group substituents, which can be the same or different, wherein “aryl group substituent” includes alkyl, substituted alkyl, aryl, substituted aryl, aralkyl, hydroxyl, alkoxyl, aryloxyl, aralkyloxyl, carboxyl, carbonyl, acyl, halo, nitro, alkoxycarbonyl, aryloxycarbonyl, aralkoxycarbonyl, acyloxyl, acyloxyl, acylamino, aroylamino, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, arylthiol, 30 alkylthio, alkylene, and -NR’R”, wherein R’ and R” can each be independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, and aralkyl. 10 Docket No. 1770.0148WO Thus, as used herein, the term “substituted aryl” includes aryl groups, as defined herein, in which one or more atoms or functional groups of the aryl group are replaced with another atom or functional group, including, for example, alkyl, substituted alkyl, halogen, aryl, substituted aryl, alkoxyl, hydroxyl, nitro, amino, 5 alkylamino, dialkylamino, sulfate, and mercapto. Specific examples of aryl groups include, but are not limited to, cyclopentadienyl, phenyl, furan, thiophene, pyrrole, pyran, pyridine, imidazole, benzimidazole, isothiazole, isoxazole, pyrazole, pyrazine, triazine, pyrimidine, quinoline, isoquinoline, indole, carbazole, and the like. 10 “Cyclic” and “cycloalkyl” refer to a non-aromatic mono- or multicyclic ring system of about 3 to about 10 carbon atoms, e.g., 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms. The cycloalkyl group can be optionally partially unsaturated. The cycloalkyl group also can be optionally substituted with an alkyl group substituent as defined herein, oxo, and/or alkylene. There can be optionally inserted along 15 the cyclic alkyl chain one or more oxygen, sulfur, or substituted or unsubstituted nitrogen atoms, wherein the nitrogen substituent is hydrogen, alkyl, substituted alkyl, aryl, or substituted aryl, thus providing a heterocyclic group. Representative monocyclic cycloalkyl rings include cyclopentyl, cyclohexyl, and cycloheptyl. Multicyclic cycloalkyl rings include adamantly, octahydronaphthyl, 20 decalin, camphor, camphane, and noradamantyl. The terms “halo”, halide”, or “halogen” as used herein refer to fluoro, chloro, bromo, and iodo groups. The term “cyano” refers to the -CN group. The term “nitro” refers to the -NO2 group. 25 As used herein, the term “room temperature” is considered to be any temperature between about 15°C and about 25°C (i.e., about 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or about 25°C). In some embodiments, the term “room temperature” is a temperature between about 18°C and about 24°C or between about 20°C and about 25°C. 11 Docket No. 1770.0148WO As used herein, the term “solvent” can refer to a carrier compound or mixture of carrier compounds that can dissolve a solute compound or compounds of interest, such as one or more of the other components of a primer composition as described herein. In some embodiments, the solvent compound or compounds 5 are liquid at room temperature and dissolve but are substantially non-reactive with the other components of a primer compositions as described herein. In particular, as used herein, the term “solvent” can refer to a liquid carrier comprising one or more organic liquid compounds that is non-aqueous or substantially non-aqueous, while, in contrast, the term “aqueous solvent” can refer to a liquid carrier that 10 comprises water. In some embodiments, the term “solvent” refers to non-protic solvents, including, but not limited to an alkane (e.g., pentane, hexane, heptane, cyclohexane, etc.), an aromatic solvent (e.g., benzene, toluene, xylene, etc.), an ether (1,4-dioxane, diethyl ether, tetrahydrofuran), a ketone (e.g., methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetone, etc.), a halogenated 15 alkane (e.g., dichloromethane, chloroform), an ester (e.g., ethyl acetate), acetonitrile, dimethylformamide, dimethyl sulfoxide, and mixtures thereof. The terms “xylene” and “xylenes” as used herein refer to an isomer of dimethylbenzene or a mixture of two or more isomers of dimethylbenzene. Unless otherwise stated, the concentrations and/or percentage (%) of 20 components of the compositions described herein (e.g., the primer compositions described herein) are expressed in terms of weight (wt) %. II. Primers for High Performance Rubber to Substrate Bonding In some embodiments, the presently disclosed subject matter is directed to aqueous- and/or solvent-based primer compositions and systems for bonding 25 rubber to a substrate, including for example metal substrates and thermoplastics. The terms “primer” and “undercoat” as used herein refer to a basecoat used to treat a substrate surface or metal surface before applying a topcoat (also referred to as a “cover coat”) adhesive. It is typically formulated to provide a maximum adhesion to a substrate, including a metal substrate and/or thermoplastic substrate, 30 and ensure better adhesion of an adhesive topcoat to the primed surface. The primer can protect against water, since once water diffuses through to a substrate 12 Docket No. 1770.0148WO surface, including to a bare metal surface, the substrate surface can suffer from oxidation and eventually corrosion or rust. In addition, the primer can protect against harsh environmental conditions, such as oils, fluids, and/or acids that can compromise the performance of bonded parts. 5 In some embodiments, the presently disclosed subject matter is directed to aqueous- and/or solvent-based primer technologies that comprise environmentally friendly, or environmentally preferred, high performance resin components, including, for example, benzoxazine resins. Unlike traditional phenolic resins, the presently disclosed primer compositions offer significant 10 advantages such as, but not limited to, synthesis using inexpensive raw materials with no use of harsh chemicals, solubility in common non-CMR organic solvents (i.e., solvents that are non-carcinogenic, non-mutagenic and non-reprotoxic), and easy dispersion in aqueous media with no pre-emulsification. Another advantage of the presently disclosed primer compositions is optimal shelf-life stability 15 before and after formulation that provides for consistent performance. Moreover, the presently disclosed primer compositions have excellent hydrophobic, chemical, thermal, and mechanical properties. Additionally, the presently disclosed primer compositions provide a significant cost reduction in materials as compared to existing primers. 20 In some aspects, the presently disclosed subject matter relates to compositions for bonding non-vulcanized elastomer compounds to substrates, including, but not limited to, various metals and thermoplastics. The compositions can be aqueous-based formulations designed as carbon neutral products to meet environmental safety standards, e.g. future needs of automotive 25 original equipment manufacturers (OEMs), or solvent-based formulations, and can be free or substantially free of monomeric phenol and formaldehyde. The present disclosure is also related to the use of benzoxazine resins as a component for a primer composition in combination with or without an adhesive for bonding non-vulcanized elastomers to other substrates and to related bonded assemblies. 30 The presently disclosed primer compositions can comprise a plurality of formulations as disclosed herein, and can include one or more of the following individual components: A. Benzoxazine Resins 13 Docket No. 1770.0148WO Benzoxazine (BZX) resin is phenolic-type resin that provides excellent adhesion to various metal and thermoplastic substrates, is capable of imparting improved chemical resistance to automotive fluids, and also provides resistance to mobile plasticizers that can migrate to the bond line from the elastomer. 5 Dinitrosobenzene (DNB) ground into xylene is an extremely active rubber curative, and BZX is unexpectedly stable with DNB. It has excellent solubility in most common organic solvents used in typical rubber-to-metal formulas and can synergistically interact with cover coat adhesives, such as those sold under the tradename CHEMLOK® (Lord Corporation, Cary, North Carolina, United 10 States of America). Without being limited and for illustrative purposes only, example benzoxazine resins include bisphenol-based benzoxazines, diamine- based benzoxazines, benzoxazines with additional crosslinking sites, bifunctional BZX compounds, monofunctional BZX compounds, biobased BZZ compounds, and BZX-containing polymers. 15 Bisphenol-based benzoxazines can have structure of the general formula: , where X₁ is a bivalent group such as, but not limited to, an alkylene group (e.g., -CH2- or -C(CH3)2-), -S-, -O-, -S(=O)2-, or -C(=O)- and R is alkyl (e.g., methyl, ethyl, n-propyl, or another C₃-C₂₄ alkyl group), substituted phenyl (e.g., phenyl 20 substituted by -Cl, -Br, -NH2, -OH, -COOH, -NO2, -NO, or another aryl group substituent), or a substituent comprising a non-benzoxazine polymerizable functional group, such as allyl, vinyl, acrylate, methacrylate, furan, acetylene, propargyl, epoxy, or maleimide. Diamine-based benzoxazines are compounds having the general formula: 25 , where X₂ is selected from -C₆H₄-X₁-C₆H₄-, naphthylene, alkylene (e.g., C1-C6 alkylene), and perfluoroalkylene (e.g., -(CF2)n-, wherein n is 1-6), where X1 is a 14 Docket No. 1770.0148WO bivalent group such as -CH₂-, -S-, -O-, -C(=O)-, S(=O)₂-, and the like, and wherein each Y₂ is a aryl group substituent, such as, but not limited to, methyl (- CH3), chloro (-Cl), bromo (-Br), amino (-NH2), carboxyl (-COOH), and nitro (- NO₂). 5 Benzoxazines with additional crosslinking sites that can be used as resins in the instantly disclosed primers include those having the general formula: , where R₁ and/or R₂ are g inking sites, such as, but not limited to, allyl groups, acetylene groups, maleimide groups, furan groups, nitrile 10 groups, epoxide groups, norbornene groups, pyrrole groups, and other functional groups, e.g.: aldehyde (-C(=O)H), hydroxymethyl (-CH2OH), amino (-NH2), carboxyl (-COOH), nitrile (-CN), halo, and cyanate (-OCN). Example R₁ and/or R2 substituents comprising an allyl group include, for example: . 15 Example R₁ and/or R₂ substituents comprising acetylene groups include, for example: . An example R₁ and/or R₂ substituent comprising a maleimide group is a substituent having the structure: 15 Docket No. 1770.0148WO . An example R₁ and/or R₂ substi furan group is a substituent having the structure: . 5 Example R1 and/or R2 substituents comprising one or more nitrile group include the following structures: . An example R1 and/or R2 substituent comprising an epoxide group is a substituent having the structure: 10 . An example R1 and/or R2 su ng a norbornene group is a substituent having the structure: . An example R1 and/or R2 subs tituent comprising a pyrrole group is a substituent 15 having the structure: . Example R₁ and/or R₂ substituents comprising acrylate or methacrylate groups can have one of the following structures: 16 Docket No. 1770.0148WO . Additi ts comprising crosslinking sites such as aldehyde, hydroxymethyl, amino, carboxyl, nitrile, halo, or cyanate functional groups can have one of the following structures: 5 . Example bifunctional benzoxazine compounds that can be used in primer formulations of the presently disclosed subject matter include those prepared from the reaction of a compound comprising at least two phenol groups (e.g., bisphenol A (BA), catechol (Cat), or pyrogallol (Pyro)) with two equivalents of an amine 10 (e.g., aniline (A), allylamine (ala), or benzylamine (ba)) and formaldehyde or from the reaction of a compound with at least two amino groups (e.g., hexamethylenediamine (HMDA) or diaminodiphenylmethane (DDM)) and two equivalents of a substituted or unsubstituted aromatic alcohol (e.g., phenol (P), 2- allylphenol (2AP), hydroxybenzaldehyde, or hydroxyphenylmaleimide (HPMI)) 15 and formaldehyde. Example bifunctional benzoxazine compounds include, for example, compounds with the structures: 17 Docket No. 1770.0148WO 18 Docket No. 1770.0148WO 19 Docket No. 1770.0148WO Example monofunctional benzoxazine compounds that can be used in primer formulations of the presently disclosed subject matter include those 5 prepared from the reaction of a phenol or catechol with an amine and formaldehyde. Example monofunctional benzoxazine structures include: 20 Docket No. 1770.0148WO 21 Docket No. 1770.0148WO O N ala Biobased benzoxazine resins that can be used in the primer formulations of the presently disclosed subject matter include benzoxazine resins made using renewable raw materials, such as, but not limited to vanillin, arbutin, cardanol, 5 guiacol, urushiol, eugenol, cardbisphenol, arbutin, lignin, chavicol, coumarin, rosin, thymol, furfurylamine and chalcone. Polymer benzoxaxine resins include polymers with pendent or main-chain benzoxazine groups. An example benzoxazine polymer with main-chain benzoxazine groups is a polymer having the structure: , bisamino monomers used to prepare the polymer. B. Bismaleimides 22 Docket No. 1770.0148WO Bismaleimide (BMIs) cures rubber through peroxide cure and Michael Addition reactions. Examples are BMIs based on methylenedianiline (DDM), oxydianiline (ODA), phenylenediamine (PDA), and others known to those skilled in the art. Without being limited and for illustrative purposes only, example BMIs 5 and corresponding chemical structures are provided below: e a thermosetting matrix with excellent thermal stability. In some aspects, the cured 10 benzoxazine/bismaleimide forms an AB crosslinked structure that can also impart increased heat resistance and coating hardness along with an increase in gas impermeability and improved aging properties. These modified resins can also increase crosslinking density and compatibility with polar elastomers, with the capability of eliminating the need for harsh chemicals. 15 C. Epoxy Resins Epoxy resins can react with benzoxazine resin to form AB crosslinked structures with high crosslinking density. Epoxy-functional resins are known in 23 Docket No. 1770.0148WO the art. Non-limiting examples of epoxy resins include bisphenol A-based epoxy resins, bisphenol F-based epoxy resins, and novolac-based epoxy resins. D. Phenolic Resins 5 In some aspects, traditional phenolic resins such as resole and novolac with different molecular structures are preferred components for performance improvement. Phenolic resins with phenol, resorcinol, pyrogallol, catecol and other phenols such as biobased phenols like cardanol or liginin can also be used. 10 E. Film Formers Film forming materials and/or film forming polymers, including halogenated and non-halogenated film forming materials, can be used in some embodiments. By way of example and not limitation, such film formers can include chlorinated and/or brominated materials, or non-chlorinated elastomers 15 or thermoplastics. Film formers can, in some aspects, provide chemical resistance, waterproofing properties, weather resistance, low permeability, adhesion, mechanical strength, good fire resistance and thermal stability. A non-limiting list of examples includes chlorinated natural and synthetic rubbers, polychloroprenes (CR), polydichlorobutadiene (PDCD), polyvinyl 20 chloride (PVC), chlorinated polyvinyl chloride (CPVC), chlorinated polyethylene (CPE), chlorosulfonated polyethylene (CSM), chlorinated polypropylene (CPP), Epichlorohydrin rubber (ECO), brominated nitrile rubber (BNR), chlorinated isobutylene-isoprene rubber (CIIR), nitrile rubber (NBR), chlorinated polystyrene (CPS), chlorinated acrylonitrile-butadiene-styrene (CABS) and chlorinated 25 paraffins and waxes. Non-chlorinated polymers include butadiene such as polybutadiene (PBD), styrene-butadiene rubber (SBR), acrylonitrile-butadiene- styrene (ABS), nitrile rubber (NBR), ethylene-propylene-diene monomer (EPDM), polyetherimide (PEI), and similars. Without being limited and for illustrative purposes only, example film 30 forming polymers and corresponding chemical structures include halogenated polybutadiene such as polychloroprene and polydichlorobutadiene and their copolymers: 24 Docket No. 1770.0148WO ; chl orinated polyolefins such as chlorinated polyethylene, chlorinated polypropylene, and their copolymers: ; 5 polyvin ylchloride (PVC) and chlorinated polyvinyl chloride (CPVC): nd bu R): . 10 F. Rubber Curatives Rubber curatives include but are not limited to dinitrosobenzene (DNB), benzoquinone dioxime (QDO), sulfur, selenium, sulufur donners peroxides such as N,N-captrolactam disulfide (CLD), dipentamethylene thiuram tetrasulfide (DPTT), 2-morpholino-dithio benzothiazole (MBSS), tetramethylthiuram15 disulfide TMTD), 4, 4’-Dithiodimorpholin (DTDM), 2-2'- dithiobis(benzothiazole) (MBTS). Without being limited and for illustrative 25 Docket No. 1770.0148WO purposes only, example rubber curatives include those having the following chemical structures: 5 Inorganic additives are commonly used to improve adhesive flow properties and prevent sagging along with other properties, such as strength, durability, and resistance to heat, moisture, and chemicals. Examples of inorganic additives that can be used in the presently disclosed primers include, but are not limited to, ceramic particles, silica, metal oxide powders such as aluminum or 10 titanium, nanoparticles such as carbon nanotubes or graphene, natural and synthetic clays, glass beads, boron nitride, zinc oxide, magnesium oxide, and carbon black as a high surface area colorant. H. Corrosion-Resistant Pigments Corrosion-resistant pigments can be used in coatings to provide an 15 additional layer of protection against corrosion. Examples include, but are not limited to, zinc phosphate, zinc chromate, and iron oxide. I. Rheology Additives 26 Docket No. 1770.0148WO Organic rheology additives that can be included in the presently disclosed primers include, but are not limited to, polyureas, such as BYK® 7420 (BYK- Chemia GmbH, Wesel, Germany), and acrylic acid salts and copolymers, such as those sold under the tradenames TEXICRYL® 13-308 (Scott Bader Company 5 Limited, Wollaston, United Kingdom) and ACRYSOL® ASE-60 (Rohm and Haas Company, Philadelphia, Pennsylvania, United States of America). J. Nanomaterials In some embodiments, nanomaterials such as graphene, graphene oxide, carbon nanotubes and others can be used in the disclosed compositions. In some 10 embodiments, the nanomaterials are those with at least one dimension that is more than about 0.1 nanometers (nm) and less than about 1 micrometer (µm). In some embodiments, a nanomaterial is a material (e.g., a powder or particle) having at least one dimension between about 0.5 nm and about 500 nm (e.g., about 1nm, about 5 nm, about 10 nm, about 15 nm, about 20 nm, about 25 nm, about 30 nm, 15 about 35 nm, about 40 nm, about 45 nm, about 50 nm, about 55 nm, about 60 nm, about 65 nm, about 70 nm, about 75 nm, about 80 nm, about 85 nm, about 90 nm, about 100 nm, about 125 nm, about 150 nm, about 175 nm, about 200 nm, about 225 nm, about 250 nm, about 275 nm, about 300 nm, about 325 nm, about 350 nm, about 375 nm, about 400 nm, about 425 nm, about 450 nm, about 475 nm or 20 about 500 nm). Thus, in some embodiments, the presently disclosed primers (e.g., for high performance rubber to substrate bonding) can comprise one or more of each of the above listed components, e.g. one or more of a benzoxazine (BZX) resin, a BMI, a rubber curative, an inorganic additive, a corrosion-resistant pigment, 25 and/or a nanomaterial. More particularly, in some embodiments, the presently disclosed primers for high performance rubber to substrate bonding can comprise BZX as a resin and BMI as co-resin, optionally with one or more film formers, e.g. chlorinated and/or non-chlorinated film formers, in either a solvent-based formulation or an 30 aqueous-based formulation. Table 1 summarizes ingredients suitable for the primer formulations for some embodiments as disclosed herein. The ingredients of Table 1 are example 27 Docket No. 1770.0148WO only, with estimated ranges of content or concentration of the total. In some embodiments one or more of the ingredients listed in Table 1 can be optional, including where one or more ingredients have a content % listed as zero “0”. 5 Table 1. Description of Ingredients in Primer Formulations Ingredients Function Content (%) 28 Docket No. 1770.0148WO Solvent or Water Carrier 65 to 85 In some embodiments, a primer formulation of the presently disclosed subject matter can comprise a component acting as a film forming polymer. Such film forming polymer component can be in the form of an elastomer, a 5 thermoplastic, or combinations thereof. Such film forming polymer component can be in the primer formulation at a concentration of about 0% to about 8% (total, or separately for each of the elastomer and thermoplastic as shown in Table 1), optionally about 0.1%, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, about 1.0%, about 1.1%, about 1.2%, 10 about 1.3%, about 1.4%, about 1.5%, about 1.6%, about 1.7%, about 1.8%, about 1.9%, about 2.0%, about 2.1%, about 2.2%, about 2.3%, about 2.4%, about 2.5%, about 2.6%, about 2.7%, about 2.8%, about 2.9%, about 3.0%, about 3.1%, about 3.2%, about 3.3%, about 3.4%, about 3.5%, about 3.6%, about 3.7%, about 3.8%, about 3.9%, about 4.0%, about 4.1%, about 4.2%, about 4.3%, about 4.4%, about 15 4.5%, about 4.6%, about 4.7%, about 4.8%, about 4.9%, about 5.0%, about 5.1%, about 5.2%, about 5.3%, about 5.4%, about 5.5%, about 5.6%, about 5.7%, about 5.8%, about 5.9%, about 6.0%, about 6.1%, about 6.2%, about 6.3%, about 6.4%, about 6.5%, about 6.6%, about 6.7%, about 6.8%, about 6.9%, about 7.0%, about 7.1%, about 7.2%, about 7.3%, about 7.4%, about 7.5%, about 7.6%, about 7.7%, 20 about 7.8%, about 7.9%, and/or about 8.0%. In some embodiments, a primer formulation can comprise a component acting as an adhesive or resin, and/or providing an adhesion functionality. Such an adhesive can comprise, for example, a benzoxazine resin, or any other suitable resin or adhesive. Such adhesive or resin can be in the primer formulation at a 25 concentration of about 3.0% to about 7.0%, optionally about 3.0%, about 3.1%, about 3.2%, about 3.3%, about 3.4%, about 3.5%, about 3.6%, about 3.7%, about 3.8%, about 3.9%, about 4.0%, about 4.1%, about 4.2%, about 4.3%, about 4.4%, about 4.5%, about 4.6%, about 4.7%, about 4.8%, about 4.9%, about 5.0%, about 5.1%, about 5.2%, about 5.3%, about 5.4%, about 5.5%, about 5.6%, about 5.7%, 29 Docket No. 1770.0148WO about 5.8%, about 5.9%, about 6.0%, about 6.1%, about 6.2%, about 6.3%, about 6.4%, about 6.5%, about 6.6%, about 6.7%, about 6.8%, about 6.9%, and/or about 7.0%. In some embodiments, a primer formulation can comprise a component 5 acting as a co-resin and/or imparting performance control in the application of the primer formulation. By way of example and not limitation, such a co-resin and/or performance enhancer can comprise, Bismaleimide (e.g. BMI 1000), Allyl- Benzoxazine (e.g. such as the benzoxazine sold under the tradename DUREZ® 34696 (The Durez Corporation, Novi, Michigan, United States of America)), or 10 any other suitable co-resin, or combination thereof. Such co-resin and/or performance enhancer can be in the primer formulation at a concentration of about 0% to about 4.0%, optionally about 0.0%, about 0.1%, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, about 1.0%, about 1.1%, about 1.2%, about 1.3%, about 1.4%, about 1.5%, about 1.6%, 15 about 1.7%, about 1.8%, about 1.9%, about 2.0%, about 2.1%, about 2.2%, about 2.3%, about 2.4%, about 2.5%, about 2.6%, about 2.7%, about 2.8%, about 2.9%, about 3.0%, about 3.1%, about 3.2%, about 3.3%, about 3.4%, about 3.5%, about 3.6%, about 3.7%, about 3.8%, about 3.9%, and/ or about 4.0%. In some embodiments, a primer formulation can comprise a catalyst and/or 20 component providing and/or enhancing cure control. By way of example and not limitation, such a catalyst and/or component providing and/or enhancing cure control can comprise, a polyphenol (e.g. a phenol-based resin sold under the tradename DUREZ® 34001 (The Durez Corporation, Novi, Michigan, United States of America); a resorcinol-based novolak resin sold under the tradename 25 SRF-1501 (SI Group, The Woodlands, Texas, United States of America)), or any other suitable catalyst, or combination thereof. Such catalyst and/or component providing and/or enhancing cure control can be in the primer formulation at a concentration of about 0% to about 3%, optionally about 0.0%, about 0.1%, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, 30 about 0.9%, about 1.0%, about 1.1%, about 1.2%, about 1.3%, about 1.4%, about 1.5%, about 1.6%, about 1.7%, about 1.8%, about 1.9%, about 2.0%, about 2.1%, about 2.2%, about 2.3%, about 2.4%, about 2.5%, about 2.6%, about 2.7%, about 2.8%, about 2.9%, and/or about 3.0%. 30 Docket No. 1770.0148WO In some embodiments, a primer formulation can comprise a surfactant and/or dispersing agent, and/or any component aiding in dispersion. By way of example and not limitation, such a surfactant and/or dispersing agent can comprise, sodium lignosulfonate (sold under the tradename MARASPERSE® 5 CBOS-4 (Borregaard AS, Sarpsborg, Norway)), or any other suitable surfactant and/or dispersing agent, or combination thereof. Such surfactant and/or dispersing agent can be in the primer formulation at a concentration of about 0% to about 1%, optionally about 0.0%, about 0.1%, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, and/or about 1.0%. 10 In some embodiments, a primer formulation can comprise an acid scavenger. By way of example and not limitation, such an acid scavenger can comprise, zinc oxide (e.g. ZOCO 102 (Zochem Inc., Brampton, Canada)), or any other suitable an acid scavenger. Such an acid scavenger can be in the primer formulation at a concentration of about 2% to about 7%, optionally about 2.0%, 15 about 2.1%, about 2.2%, about 2.3%, about 2.4%, about 2.5%, about 2.6%, about 2.7%, about 2.8%, about 2.9%, about 3.0%, about 3.1%, about 3.2%, about 3.3%, about 3.4%, about 3.5%, about 3.6%, about 3.7%, about 3.8%, about 3.9%, about 4.0%, about 4.1%, about 4.2%, about 4.3%, about 4.4%, about 4.5%, about 4.6%, about 4.7%, about 4.8%, about 4.9%, about 5.0%, about 5.1%, about 5.2%, about 20 5.3%, about 5.4%, about 5.5%, about 5.6%, about 5.7%, about 5.8%, about 5.9%, about 6.0%, about 6.1%, about 6.2%, about 6.3%, about 6.4%, about 6.5%, about 6.6%, about 6.7%, about 6.8%, about 6.9%, and/or about 7.0%. In some embodiments, a primer formulation can comprise a rheological agent, e.g. silica, or similar component, for rheology control. By way of example 25 and not limitation, a silica (e.g. a silica sold under the tradenames AEROSIL® 200 (Evonik Operations, GmbH; Essen, Germany); HJSIL™ R110 (Minmetals East; Jiaozuo City, China); or CAB-O-SIL™ M-5 (Cabot Corporation, Boston, Massachusetts, United States of America)) or component for rheology control, i.e. a rheological agent, can comprise surface untreated silica, surface treated silica, 30 or combination thereof. Such a silica, or similar component for rheology control, can be in the primer formulation at a concentration of about 0% to about 5%, optionally about 0%, about 0.1%, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, about 1.0%, about 1.1%, 31 Docket No. 1770.0148WO about 1.2%, about 1.3%, about 1.4%, about 1.5%, about 1.6%, about 1.7%, about 1.8%, about 1.9%, about 2.0%, about 2.1%, about 2.2%, about 2.3%, about 2.4%, about 2.5%, about 2.6%, about 2.7%, about 2.8%, about 2.9%, about 3.0%, about 3.1%, about 3.2%, about 3.3%, about 3.4%, about 3.5%, about 3.6%, about 3.7%, 5 about 3.8%, about 3.9%, about 4.0%, about 4.1%, about 4.2%, about 4.3%, about 4.4%, about 4.5%, about 4.6%, about 4.7%, about 4.8%, about 4.9%, and/or about 5.0%. In some embodiments, a primer formulation can comprise a corrosion inhibitor, or similar compound for rust prevention. By way of example and not 10 limitation, such a corrosion inhibitor or component for rust prevention can comprise any suitable corrosion inhibitor such as zinc-5-nitroisophthalate. Such a corrosion inhibitor can be in the primer formulation at a concentration of about 0% to about 2%, optionally about 0%, about 0.1%, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, about 1.0%, 15 about 1.1%, about 1.2%, about 1.3%, about 1.4%, about 1.5%, about 1.6%, about 1.7%, about 1.8%, about 1.9%, and/or about 2.0%. In some embodiments, a primer formulation can comprise a filler. By way of example and not limitation, such a filler can comprise any compound suitable to act as a filler, including titanium oxide (e.g. a titanium oxide sold under the 20 tradename TI-PURE® R900 (The Chemours Company FC, LLC; Wilmington, Delaware, United States of America)). Such a filler can be in the primer formulation at a concentration of about 2% to about 5%, optionally about 2.0%, about 2.1%, about 2.2%, about 2.3%, about 2.4%, about 2.5%, about 2.6%, about 2.7%, about 2.8%, about 2.9%, about 3.0%, about 3.1%, about 3.2%, about 3.3%, 25 about 3.4%, about 3.5%, about 3.6%, about 3.7%, about 3.8%, about 3.9%, about 4.0%, about 4.1%, about 4.2%, about 4.3%, about 4.4%, about 4.5%, about 4.6%, about 4.7%, about 4.8%, about 4.9%, and/or about 5.0%. In some embodiments, a primer formulation can comprise a coloring agent, or a black coloring agent. By way of example and not limitation, such a coloring 30 agent, or a black coloring agent, can comprise any compound suitable to add, enhance or change the color of the primer, including carbon black, any dye, any pigment, organic pigments, inorganic pigments, or any combination thereof. Such a coloring agent can be in the primer formulation at a concentration of about 0% 32 Docket No. 1770.0148WO to about 1%, optionally about 0% to about 1%, optionally about 0.0%, about 0.1%, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, and/or about 1.0%. In some embodiments, a primer formulation can comprise a carrier. An 5 aqueous carrier can be used in the aqueous formulations, whereas a solvent carrier can be used in the solvent-based formulations. By way of example and not limitation, such a carrier can comprise any compound suitable to act as a carrier or carrying agent for the primer formulation, including water (e.g. deionized (DI) water) or any solvent (e.g. xylene, cyclohexanone), or any combination thereof. 10 Such a coloring agent can be in the primer formulation at any concentration needed to bring the final formulation to 100% in view of the other components or ingredients, including a concentration of about 65% to about 85%, optionally about 65.0%, about 65.5%, about 66.0%, about 66.5%, about 67.0%, about 67.5%, about 68.0%, about 68.5%, about 69.0%, about 69.5%, about 70.0%, about 70.5%, 15 about 71.0%, about 71.5%, about 72.0%, about 72.5%, about 73.0%, about 73.5%, about 74.0%, about 74.5%, about 75.0%, about 75.5%, about 76.0%, about 76.5%, about 77.0%, about 77.5%, about 78.0%, about 78.5%, about 79.0%, about 79.5%, about 80.0%, about 80.5%, about 81.0%, about 81.5%, about 82.0%, about 82.5%, about 83.0%, about 83.5%, about 84.0%, about 84.5%, and about 85.0%. 20 In some embodiments, the presently disclosed subject matter provides methods of bonding elastomer to a substrate using a primer composition as disclosed herein, in some embodiments in conjunction with an adhesive, i.e. a topcoat adhesive. More particularly, such aqueous and/or solvent primer compositions and systems, as disclosed herein, can be used for bonding rubber to 25 a substrate, including for example metal substrates and thermoplastics. In some embodiments, the disclosed primers or undercoatings act as base-coat used to treat a substrate surface or metal surface, as well as act as the adhesive or bonding agent. However, in other embodiments, the disclosed primers or undercoatings are a base-coat used to treat a substrate surface or metal surface before applying 30 a separate topcoat adhesive. 33 Docket No. 1770.0148WO Example elastomers include, but are not limited to, natural rubber (NR), butadiene rubber (BR), chloroprene rubber (CR), styrene butadiene rubber (SBR), nitrile rubber (NBR), NR/BR blends, and SBR/BR blends. In some embodiments, the method comprises: (i) applying a primer 5 composition of the presently disclosed subject matter to a substrate; (ii) applying an adhesive to the primer after drying. In some embodiments, the primer composition is applied to the substrate surface via brush or roll application. In some embodiments, one layer of primer is applied to the substrate surface. In some embodiments, multiple layers (e.g., 2, 10 3, 4, 5, 6, or more) layers of primer are applied to a substrate surface, followed by application of an adhesive. In some embodiments, the substrates can be cleaned and/or buffed prior to application of the primer and/or adhesive. In some embodiments, the presently disclosed subject matter provides a 15 bonded assembly prepared according to method as described herein or using a primer composition and an adhesive as described herein. In some embodiments, the substrate is a metal substrate (e.g., a steel substrate) or a thermoplastic. In some embodiments, the presently disclosed adhesive can be used to provide a bonded assembly and/or the presently disclosed method can provide a 20 bonded assembly having a peel strength of about 60 to 100 pounds per linear inch (PLI) or more after 10 minutes of curing at elevated temperature. In some embodiments, the presently disclosed primers are provided for use in applications where bonding non-vulcanized elastomer compounds to substrates is required, including various metals and thermoplastics. The primer 25 compositions can be particularly useful where formulations designed as carbon neutral products to meet environmental safety standards, e.g. future needs of automotive original equipment manufacturers (OEMs), or solvent-based formulations, and free or substantially free of monomeric phenol and formaldehyde, are needed. In some embodiments, such applications can be in any 34 Docket No. 1770.0148WO industrial industry, including but not limited to automotive, industrial equipment, mining, manufacturing, etc. EXAMPLES The following examples are included to further illustrate various 5 embodiments of the presently disclosed subject matter. However, those of ordinary skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the presently disclosed subject matter. 10 EXAMPLE 1 Table 2, below, summarizes the components of an example solvent primer formulation of the presently disclosed subject matter. Table 2. Use of Chlorinated Polyethylene as Film Former Content 35 Docket No. 1770.0148WO Carbon Black Color 0.75 EXAMPLE 2 Table 3, below, summarizes the components of another example solvent primer formulation of the presently disclosed subject matter. 5 Table. 3. Use of Chlorinated Polyvinylchloride (CPVC) as Film Former Ingredients Function Content (%) 36 Docket No. 1770.0148WO Total 100 EXAMPLE 3 Table 4, below, summarizes the components of another example solvent primer formulation of the presently disclosed subject matter. 5 Table. 4. Use of Polychloroprene as a Film Former Ingredients Function Content (%) 37 Docket No. 1770.0148WO EXAMPLE 4 Table 5, below, summarizes the components of another example solvent primer formulation of the presently disclosed subject matter. Table. 5. Use of Thermoplastic Polyetherimide as Non-Chlorinated Film 5 Former Ingredients Function Content (%) EXAMPLE 5 Table 6, below, summarizes the components of another example solvent primer formulation of the presently disclosed subject matter. 38 Docket No. 1770.0148WO Table. 6. Use of Bismaleimide as Co-Resin Content EXAMPLE 6 Table 7, below, summarizes the components of another example solvent 5 primer formulation of the presently disclosed subject matter. Table. 7. Using Allyl-Containing Benzoxazine as Co-Resin 39 Docket No. 1770.0148WO Content EXAMPLE 7 Table 8, below, summarizes the components of another example primer formulation of the presently disclosed subject matter. 5 Table. 8. Use of Carboxylated Styrene-Butadiene Latex as Film Former in Aqueous Formulation (110-1) 40 Docket No. 1770.0148WO Content EXAMPLE 8 Experiments were conducted to test the efficacy of the presently disclosed primer compositions when used with adhesives to bond to substrates. Below are 5 descriptions of various failure type tests per ASTM International D429. Cement-to-Metal (CM) Failures • Designated as CM, cement = primer or adhesive 41 Docket No. 1770.0148WO • Primer or adhesive failure at the metal or substrate interface Cement-to-Primer (CP) Failure • Designated - CP • Failure occurs between the primer and the adhesive 5 Cohesive Failure • Not an ASTM mode, failure occurs within either the primer or adhesive layer • 5% occurrence in industry Rubber-to-Cement (RC) Failure 10 • Designated as RC, cement = adhesive • Failure occurs between rubber and adhesive • Look for evidence of adhesive adhering to substrate, but not to rubber surface Rubber Retention 15 • Designated as R • Failure within the stock rubber These various types of failures in bonding a component, e.g. rubber to a substrate, are illustrated in FIG 1. More particularly, FIG. 1 is a schematic illustrating types of failures and failure points in adhesive to metal or adhesive to 20 substrate bonding in accordance with the presently disclosed subject matter. Testing results are summarized in FIGS. 2 to 7. FIG. 2. is a graphical depiction of data from testing primary bonding of solvent-based benzoxazine primers on coupons using CHEMLOK® 6125 as a topcoat adhesive and with bonding at 275°F (135°C) and 320°F (160°C). This data shows that the presently 25 disclosed benzoxazine primer technology produced better rubber retention than the control primer (CHEMLOK® 205) at the lower bonding temperature (275°F) and similar rubber retention at the higher bonding temperature (320°F). FIG. 3 is a graphical depiction of data from testing the performance of chlorinated polyethylene (HPE2200) and chlorinated polyvinyl chloride (CPVC) 30 as film-formers in benzoxazine (BZX) primers using CHEMLOK® 6411 as adhesive. The primer formulation comprising HPE2200 and BZX (HPE2200- BZX) was aged at 50°C for 5 weeks for performance consistency. The data 42 Docket No. 1770.0148WO demonstrates excellent shelf-life stability of the BZX base primer technology with equivalent rubber retention compared to a control primer (CHEMLOK® 205), including boiling water and salt spray environmental resistance. FIG. 4 is a graphical depiction of data from performance testing of a BZX 5 primer comprising chlorinated polyethylene (HPE2200) as film former and bismaleimide as co-resin in benzoxazine primer using CHEMLOK® 6125 as a topcoat adhesive. Here, the data shows that the performance of this embodiment of the benzoxazine primer is comparable to a control primer (CHEMLOK® 205). FIG. 5 is a graphical depiction of data from testing of performance of 10 chlorinated polyvinylchloride (CPVC) as film former in benzoxazine primer using CHEMLOK® 6125 as an adhesive. The data here demonstrates that the performance of this embodiment of the benzoxazine primer is comparable to a control primer CHEMLOK® 205). In addition, the use of CPVC did not compromise the performance of the benzoxazine primer. 15 FIG. 6 is a graphical depiction of data from testing of the use of benzoxazine aqueous primer (referred to herein as “110-1”) with CHEMLOK® 8212 and 8560-1 as aqueous adhesives. The data shows primary bonding of 2 and 4 min prebake resistance on coupons, where an aqueous primer (CHEMLOK® 8008) was used as a control. Here, the data shows that an aqueous embodiment of 20 the present benzoxazine primer technology produces equivalent performance to control aqueous primer and offers equivalent prebake resistance. FIG.7 is a graphical depiction of data from testing of the use of exemplary benzoxazine aqueous primer 110-1 with CHEMLOK® 8212 and 8560-1 as aqueous topcoat adhesives. The data shows primary bonding and 24h boiling 25 water data, where aqueous CHEMLOK® 8008 primer was used as a control. This data confirms that an aqueous benzoxazine primer had equivalent or better boiling water performance compared to the aqueous control primer. It will be understood that various details of the presently disclosed subject matter may be changed without departing from the scope of the presently 30 disclosed subject matter. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation. 43

Claims

Docket No. 1770.0148WO CLAIMS What is claimed is: 1. A primer composition for rubber to substrate bonding, the primer composition comprising: 5 a film forming polymer, wherein the film forming polymer comprises a chlorinated and/or non-chlorinated film former, a resin, optionally a benzoxazine (BZX) resin; a filler; and a carrier, wherein the carrier is a solvent carrier or an aqueous carrier. 10 2. The primer composition of claim 1, further comprising a co-resin, optionally a bismaleimide (BMI). 3. The primer composition of claim 2, wherein the resin comprises BZX at a concentration of about 3.0% to about 7.0%, and the co-resin comprises BMI at a concentration of about 0.5% to about 4%. 15 4. The primer composition of any one of claims 1-3, further comprising one or more of: a catalyst; a surfactant; an acid scavenger; 20 a rheological agent; a corrosion inhibitor; a coloring agent; and/or combinations thereof. 5. The primer composition of any one of claims 1-4, further comprising a rubber 25 curative, an inorganic additive, and/or nanomaterials, optionally wherein the inorganic additive is selected from the group consisting of ceramic particles, silica, metal oxide powders, natural and synthetic clays, glass beads, boron nitride, zinc oxide, magnesium oxide, and carbon black. 6. The primer composition of claim 4 or claim 5, wherein the catalyst is at a 30 concentration of about 0.1% to about 3%; wherein the surfactant is at a 44 Docket No. 1770.0148WO concentration of about 0.1% to about 1%; wherein the acid scavenger is at a concentration of about 2% to about 7%; wherein the rheological agent is at a concentration of about 0.1% to about 5%; wherein the corrosion inhibitor is at a concentration of about 0.1% to about 2%; wherein the filler is at a concentration 5 of about 2% to about 5%; wherein the coloring agent is at a concentration of about 0.1% to about 1%. 7. The primer composition of claim 1, wherein the primer composition comprises an aqueous carrier, optionally wherein the aqueous carrier is about 65% to about 85% of the primer composition. 10 8. The primer composition of claim 1, wherein the primer composition comprises a solvent carrier, optionally wherein the solvent carrier is about 65% to about 85% of the primer composition. 9. The primer composition of any one of claims 1, 7, or 8, wherein the primer composition is soluble in non-carcinogenic, non-mutagenic and non-reprotoxic 15 chemical (non-CMR) solvents. 10. The primer composition of any one of claims 1-9, comprising: (a) about 7.5% film forming polymer, optionally a chlorinated polyethylene; (b) about 5.0% BZX resin; 20 (c) about 1.25% catalyst for cure control, optionally a polyphenol; (d) about 4.25% acid scavenger, optionally zinc oxide; (e) about 1.25% rheological agent, optionally silica; (f) about 5.0% filler, optionally titanium oxide; (g) about 0.75% coloring agent, optionally carbon black; and 25 (h) about 75.0% solvent, optionally xylene. 11. The primer composition of any one of claims 1-9, comprising: (a) about 5.7% film forming polymer, optionally a chlorinated polyvinylchloride; (b) about 3.7% BZX resin; 30 (c) about 1.0% catalyst for cure control, optionally a polyphenol; 45 Docket No. 1770.0148WO (d) about 3.2% acid scavenger, optionally zinc oxide; (e) about 1.0% rheological agent, optionally silica; (f) about 3.8% filler, optionally titanium oxide; (g) about 0.6% coloring agent, optionally carbon black; and 5 (h) about 81.0% solvent, optionally cyclohexanone. 12. The primer composition of any one of claims 1-9, comprising: (a) about 2.75% film forming polymer, optionally polychloroprene; (b) about 6.5% BZX resin; (c) about 1.25% catalyst for cure control, optionally a polyphenol; 10 (d) about 6.25% acid scavenger, optionally zinc oxide; (e) about 1.25% rheological agent, optionally silica; (f) about 5.5% filler, optionally titanium oxide; (g) about 1.75% coloring agent, optionally carbon black; (h) about 0.75% corrosion inhibitor; and 15 (i) about 74.0% solvent, optionally xylene. 13. The primer composition of any one of claims1-9, comprising: (a) about 7.5% film forming polymer, optionally polyetherimide; (b) about 5.0% BZX resin; (c) about 1.25% catalyst for cure control, optionally a polyphenol; 20 (d) about 4.25% acid scavenger, optionally zinc oxide; (e) about 1.25% rheological agent, optionally silica; (f) about 5.0% filler, optionally titanium oxide; (g) about 0.27% coloring agent, optionally carbon black; and (h) about 75.0% solvent, optionally 60% methyl isobutyl ketone (MIBK) 25 and 15% xylene. 14. The primer composition of any one of claims 1-9, comprising: (a) about 7.5% film forming polymer, optionally chlorinated polyethylene; (b) about 4.5% BZX resin; (c) about 2.4% co-resin, optionally bismaleimide (BMI); 30 (d) about 1.5% catalyst for cure control, optionally a polyphenol; (e) about 6.0% acid scavenger, optionally zinc oxide; 46 Docket No. 1770.0148WO (f) about 1.5% rheological agent, optionally silica; (g) about 6.0% filler, optionally titanium oxide; (h) about 0.6% coloring agent, optionally carbon black; and (i) about 70.0% solvent, optionally 42% MIBK and 28% xylene. 5 15. The primer composition of any one of claims 1-9, comprising: (a) about 7.5% film forming polymer, optionally chlorinated polyethylene; (b) about 4.5% BZX resin; (c) about 0.5% co-resin, optionally allyl-BZX; (d) about 1.25% catalyst for cure control, optionally a polyphenol; 10 (e) about 4.25% acid scavenger, optionally zinc oxide; (f) about 1.25% rheological agent, optionally treated silica; (g) about 5.0% filler, optionally titanium oxide; (h) about 0.75% coloring agent, optionally carbon black; and (i) about 75.0% solvent, optionally xylene. 15 16. The primer composition of any one of claims 1-9, comprising: (a) about 3.0% film forming polymer, optionally carboxylated styrene- butadiene rubber; (b) about 4.75% BZX resin; (c) about 0.5% surfactant, optionally acrylic co-polymer salt; 20 (d) about 1.33% dispersing agent, optionally sodium lignosulfonate; (e) about 1.25% catalyst for cure control, optionally a polyphenol; (f) about 5.3% acid scavenger, optionally zinc oxide; (g) about 1.6% rheological agent, optionally untreated silica; 25 (h) about 1.52% filler, optionally titanium oxide; (i) about 0.75% coloring agent, optionally carbon black; and (j) about 80.0% aqueous solvent, optionally deionized water. 47