Modular protective coating system, coated article, coating composition, and methods of forming the same

Abstract

MODULAR PROTECTIVE COATING SYSTEM, COATED ARTICLE, COATING COMPOSITION, AND METHODS OF FORMING THE SAME A modular protective coating system for solid substrates is disclosed, which may be configured as a single layer embodiment comprising a single coating region on a substrate, or as a multilayer embodiment comprising a substrate, an optional primer layer, a base region, and an outer region. The coating architecture comprises a film forming adhesion promoting polymeric material, an inorganic particulate structuring agent, a crosslinking or network forming agent, a low surface energy surface forming material, one or more organosilicon surface modifying compounds. The invention further provides coating compositions, coated articles, and methods for forming the same on metal, ceramic, glass, polymeric, composite, and mixed material substrates. The coating system is suitable for ambient or low temperature curing and for applications requiring hydrophobic behavior, self cleaning behavior, and resistance to fouling, scaling, moisture, steam, detergents, and heat.

Description

[0001] MODULAR PROTECTIVE COATING SYSTEM, COATED ARTICLE, COATING COMPOSITION, AND METHODS OF FORMING THE SAME FIELD OF DISCLOSURE

[0002] The present invention generally relates to the field of functional surface engineering and, more particularly, to modular protective coating systems for solid substrates. The disclosed subject matter encompasses modular coating architectures including single layer systems, multilayer systems, and primer assisted systems, as well as associated coated articles, coating compositions, precursor formulations, and methods for producing the same.

[0003] Further, the present invention pertains to coating structures engineered for application on diverse substrates selected from metal, ceramic, glass, polymeric, composite, and mixed material surfaces. The disclosed coating structures comprise coordinated classes of materials such as adhesion promoting polymeric constituents, inorganic particulate structuring constituents, crosslinking or network forming constituents, low surface energy surface forming constituents, organosilicon surface modifying constituents, and, optionally, interfacial primer constituents.

[0004] The disclosed subject matter is further directed to protective coating systems formulated to maintain controlled surface functionality under aggressive environmental and operational conditions. Such conditions encompass exposure to moisture, steam, detergents, humidity, wetting, and thermal stress, as well as environments prone to fouling or scaling, hygiene sensitive areas, and cleaning intensive service conditions. Accordingly, the functional scope of the disclosed systems includes hydrophobic behavior, self cleaning behavior, chemical resistance, fouling resistance, scaling resistance, robust interfacial durability, surface durability, environmental durability, and combinations thereof, while maintaining cure compatibility under ambient conditions or low elevated temperature conditions.Finally, the present invention relates to industrially deployable coating technologies adaptable for factory applications, field applications, retrofit applications, and maintenance applications across a broad spectrum of end uses. These applications include infrastructure, process equipment, sanitary fixtures, transport surfaces, architectural building surfaces, healthcare environments, food contact adjacent surfaces, and similar environments requiring durable protective performance.

[0005] BACKGROUND

[0006] Protective coating technology encompasses numerous systems directed toward superhydrophobicity, self cleaning behavior, anti fouling properties, water repellency, chemical resistance, optical utility, electrical insulation, environmental decontamination, and eco compatibility. While the known art establishes multiple distinct technical pathways to achieve these properties, existing systems generally fall into four primary classes: (1) broad superhydrophobic coating systems and preparation methods; (2) PDMS / silica / organosilicon chemistry systems; (3) chitosan and alternative biopolymer surface treatment systems; and (4) fluorine free or non fluorinated superhydrophobic compositions.

[0007] Within the first class, conventional systems often rely on highly specific, multi step chemical processes. For example, KR20220154336A describes a sequential two layer process wherein a first coating layer comprising a titanium dioxide nanoparticle epoxy resin composite is followed by a second layer of fluorocarbon silane modified silica nanoparticles, requiring intermediate curing. Such systems are generally directed to fluorinated epoxy based multilayer applications for self cleaning and anti-icing performance. Similarly, US20110220855A1 discloses a self-cleaning and self decontaminating composition based on photochemically active semiconductor metal oxide nanoparticles, particularly anatase titanium dioxide, dispersed in an organic resin or inorganic binder, functioning primarily as a UV activated oxide system. Another approach, detailed in CN 114752275 A, utilizes a spray applied biomimetic coatingcomposition prepared from epoxy resin, PDMS, micro and nano KH550 modified ZnO, and curing agents. Cured at 80°C, this specific epoxy / PDMS / ZnO formulation is designed strictly to reproduce a biomimetic micro / nano hierarchical surface on select substrates.

[0008] The second class of prior art relies heavily on silicone and specialized silica modifications. CN117186768A describes a single formulation, self healing, fluorine free superhydrophobic composition prepared by modifying silica nanoparticles with trimethylchlorosilane, dispersing them in PDMS, and applying a curing agent. WO2012 / 156173 Al discloses a silica / silicone / solvent coating restricted to transparent or translucent superhydrophobic hard surface applications, comprising microclusters of silica based particles and silicone of a defined viscosity. Other systems in this class depend on fluorination to achieve desired surface energies. US11725110B2 describes a binding layer combined with a hydrophobic layer comprising perfluoroalkyl functionalized silica nanoparticles, while KR101425897B1 relies on a fluorinated silica sol gel composition formed from colloidal silica, alkyl fluorosilane, and glycidoxy alkyl trimethoxy silane, specifically engineered for high voltage insulation to suppress leakage current and flashover.

[0009] The third class explores biopolymers, though largely in isolated or chemically restricted contexts. EP2271593A1 is directed to a glass specific method requiring chitosan to be bonded directly to a glass surface, followed by chemical or enzymatic treatment to render that specific bonded layer hydrophobic. WO2020234643A1 describes a formulation utilizing a chitosan based agent, such as chitosan acetate or citrate acetate, strictly as a carrier in cleaner, polish, or finish systems. While these documents establish the use of chitosan in surface treatments, their functional mechanisms remain narrow.

[0010] The fourth class addresses the growing demand for non fluorinated systems. WO2019 / 045732 Al describes water based superhydrophobic compositions containing a fluorine free hydrophobic matrix, including polyolefin dispersions, naturalwaxes, or synthetic waxes, combined with plant based filler particles, particularly cellulosic materials. Alongside the aforementioned CN117186768A, these references establish that non fluorinated superhydrophobicity is known, yet typical solutions remain bound to specific wax, polyolefin, or PDMS matrices.

[0011] While the foregoing references demonstrate that superhydrophobic or hydrophobic surface functionality has been pursued through various avenues, including fluorinated silica systems, oxide based UV systems, PDMS / silica blends, biomimetic particulate hierarchies, water based waxes, and isolated chitosan treatments, they also highlight a distinct fragmentation in the art. Known solutions are materially confined to specific chemistries, inflexible layer constructions, narrow substrate compatibility, restricted end use environments, or singular functional mechanisms.

[0012] Overall, the deficiencies in the known prior art are distinctly structural, compositional, and functional. The prior art fails to provide a cohesive coating technology that unifies broad substrate compatibility, optional primer assisted interfacial engineering, single layer or multilayer architectural flexibility, coordinated material family design, low temperature or ambient temperature process compatibility, and robust protective performance under harsh service exposure within a single, scalable platform.

[0013] Consequently, a significant need exists for a modular protective coating technology that is not restricted to fluorinated epoxy / TiO2 silica processes, UV activated decontamination, single formulation PDMS / silica systems, glass specific chitosan hydrophobization, plant filler wax systems, or niche electrical insulation chemistries. A need further exists for a highly adaptable coating platform capable of expression as either a single layer or a multilayer system, capable of optional integration with a primer layer, and capable of synergizing adhesion and interfacial durability with low surface energy outer protection. Furthermore, it would be highly desirable to provide such a platform that is applicable to a broad array of metal, ceramic, glass, polymeric, and composite substrates, formulated as eco compliant and PFAS free, deployable under ambient or low temperature curing conditions, and durable enough to withstandextreme moisture, heat, steam, detergent, hygiene sensitive, fouling, and scaling environments.

[0014] The present invention is directed to overcoming these and other deficiencies in the prior art.

[0015] OBJECTS OF THE INVENTION

[0016] It is a principal object of the present invention to provide a protective coating system having a modular architectural form, applicability across multiple substrate classes, defined protective surface functionality, and durable performance under service exposure.

[0017] It is a further object of the invention to provide a coating platform capable of expression as a single layer system, a multilayer system, or a primer assisted system. It is a related object to provide corresponding coated articles, coating compositions, precursor formulations, and methods of formation.

[0018] It is a further object to provide a coating architecture wherein distinct structural regions perform discrete technical functions. These functions include, but are not limited to, adhesion promotion, interfacial stabilization, film formation, surface structuring, crosslinked network formation, and the generation of a low surface energy outer surface.

[0019] It is a further object to provide a coating composition comprising coordinated classes of materials. The materials are selected from film forming adhesion promoting polymeric materials, inorganic particulate structuring agents, crosslinking or network forming agents, low surface energy surface forming materials, organosilicon surface modifying compounds, and optional interfacial primer constituents.

[0020] It is a further object to provide a coating system applicable across multiple substrate classes. Such substrates include, but are not limited to, metal, ceramic, glass,polymeric, and composite substrates, as well as mixed material articles and installed equipment surfaces.

[0021] It is a further object to provide a coating technology compatible with standard deposition operations, including spraying, dipping, brushing, wiping, rolling, flow coating, and sequential deposition. It is a related object to provide a coating technology deployable for laboratory scale, manufacturing scale, field use, and retrofit applications.

[0022] It is a further object to provide a coating system capable of formation under ambient curing conditions, room temperature curing conditions, or low elevated temperature curing conditions. It is a related object to reduce required process temperature for compatibility with temperature sensitive substrates and installed structures and for reduction of process energy demand.

[0023] It is a further object to provide a coating system suitable for exposure to moisture, humidity, wetting, elevated temperature steam exposure, detergents, heat, fouling, and scaling. It is a related object to provide a coating system capable of coordinated expression of water repellency, self cleaning behavior, chemical resistance, fouling resistance, scaling resistance, interfacial durability, and environmental durability. The coating system is suitable for hygiene sensitive and cleaning intensive service conditions.

[0024] It is a further object to provide embodiments utilizing low toxicity, reduced hazard, reduced VOC, fluorine free, or PFAS free chemistry.

[0025] It is a further object to provide embodiments incorporating naturally derived polymers, biopolymers, polysaccharides, plant derived materials, or biodegradable components. In such embodiments, the biopolymeric or naturally derived constituents contribute to adhesion, film formation, interfacial stabilization, network development, and surface support. These constituents maintain architectural compatibility with the inorganic particulate systems, crosslinking systems, organosilicon surface modifying systems, and low surface energy surface forming systems.It is a further object to provide an optional primer assisted interfacial system. This system improves substrate bonding, coating coverage, adhesion retention, coating continuity, and interfacial durability relative to an unprimed substrate condition. It is a further object to provide a formulation platform capable of supporting multiple embodiment families. These families are adapted for defined functional requirements, specific substrate chemistries, substrate geometries, and service environment conditions.

[0026] It is a further object to provide a protective coating technology that reduces dependence on high temperature curing, fluorinated surface chemistry, and solvent intensive processes, while maintaining protective and surface functional performance.

[0027] It is a final object to provide an industrially deployable coating platform that unifies architectural flexibility, compositional breadth, process practicality, substrate adaptability, and protective surface function.

[0028] SUMMARY

[0029] The present invention provides a protective coating system having a modular architectural form. In various aspects, the invention provides coating systems, coating compositions, coated articles, precursor formulations, methods for preparing coating compositions, and methods for forming coated articles adapted for service under defined exposure conditions.

[0030] In one aspect, the invention provides a coating architecture disposed of on a substrate. The architecture comprises at least one coating region and an optional primer layer. The architecture is configured as a single layer embodiment or a multilayer embodiment. The multilayer embodiment comprises a base region and an outer region, optionally in combination with an interfacial primer region.

[0031] In another aspect, the structural regions of the coating architecture comprise coordinated classes of materials. These coordinated classes are selected from filmforming adhesion promoting polymeric materials, inorganic particulate structuring agents, crosslinking or network forming agents, low surface energy surface forming materials, organosilicon surface modifying compounds, and optional interfacial primer constituents.

[0032] In a further aspect, the invention provides a structural allocation of function within the coating architecture. In multilayer embodiments, the interfacial region provides substrate bonding, coating attachment, adhesion retention, and coating continuity; the base region provides film formation, structural support, and reinforcement; and the outer region provides low surface energy surface expression, hydrophobic surface behavior, self cleaning surface behavior, chemical resistance, fouling resistance, and scaling resistance. In single layer embodiments, interfacial adhesion function, structural function, and protective surface function are integrated within a single coating region.

[0033] In another aspect, the invention provides coating compositions formulated to generate the defined architecture. The coating composition may comprise a single formulation or a plurality of formulations configured for sequential deposition. The composition comprises constituents selected from naturally derived polymers, biopolymers, polysaccharides, semi synthetic polymers, synthetic polymers, inorganic oxides, inorganic particulates, organic crosslinking agents, inorganic crosslinking agents, silane compounds, siloxane compounds, and optional additives adapted for stabilization, reinforcement, surface modification, or network development.

[0034] In a further aspect, the invention provides coated articles comprising the protective coating system disposed on a substrate. The substrate is selected from metal, ceramic, glass, polymeric, and composite substrates, including mixed material articles. The coated articles are configured for service conditions comprising exposure to moisture, humidity, wetting, elevated temperature steam, detergents, heat, fouling, and scaling. In another aspect, the invention provides a method for forming the protective coating system. The method comprises providing a substrate, optionally executing substratepreparation, optionally forming a primer layer, and depositing one or more coating compositions. Deposition is carried out by spraying, dipping, brushing, wiping, rolling, flow coating, or sequential deposition. The method further comprises converting the deposited composition into the protective coating system via drying, curing, setting, condensation, or crosslinking. In specified embodiments, curing is carried out under ambient conditions, room temperature conditions, or low elevated temperature conditions. The method is compatible with heat sensitive substrates, field deployments, and retrofit applications.

[0035] In specific embodiments, the protective coating system utilizes fluorine free, PFAS free, or reduced VOC chemistry. Certain embodiments incorporate biodegradable, bio based, or naturally derived constituents. In such embodiments, naturally derived or biopolymeric constituents are integrated with inorganic particulate constituents and organosilicon constituents to form the protective coating architecture.

[0036] Accordingly, the present invention provides a modular protective coating platform defined by functional allocation, compositional adaptability, and applicability across multiple substrate classes, layer configurations, and exposure environments, thereby providing defined surface functionality comprising hydrophobicity, self cleaning behavior, chemical resistance, fouling resistance, and scaling resistance.

[0037] BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 presents a broad schematic cross sectional representation of a protective coating system comprising a substrate (101), an optional primer layer (102) disposed on the substrate (101), a base region (103) disposed on the optional primer layer (102) or directly on the substrate (101), and an outer region (104) disposed on the base region (103).

[0039] Figure 2 presents a schematic cross sectional representation of a multilayer coating system comprising a substrate (201), a primer layer (202) disposed on the substrate(201), a base region (203) disposed on the primer layer (202), and an outer region (204) disposed on the base region (203).

[0040] Figure 3 presents a schematic cross sectional representation of a single layer coating embodiment comprising a substrate (301) and a single coating region (302) disposed on the substrate (301), wherein the single coating region (302) comprises an integrated multifunctional coating architecture.

[0041] Figure 4 presents a schematic structural representation of functional allocation within a modular coating architecture comprising a substrate (401), a primer function region (402) disposed on the substrate (401), a base or interfacial function region (403) disposed on the primer function region (402) or directly on the substrate (401), and a protective outer region 404 disposed on the base or interfacial function region (403). Figure 5 presents a schematic process flow representation of a method for forming a protective coating system, comprising providing a substrate (501), optionally carrying out surface preparation (502), optionally forming a primer layer (503), forming one or more coating regions (504), selectively forming either a single layer system (505) or a multilayer system (506), processing, curing, or setting the coating system (507), and forming a protective coated article (508).

[0042] Figure 6 presents a schematic representation of substrate classes and application modes of the coating system, comprising substrate classes (601), application modes (602), a protective coating system (603), and a coated article (604) formed therefrom.

[0043] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] The present invention provides a protective coating technology characterized by a modular architectural form. Disclosed herein are coating systems, coating compositions, coated articles, precursor formulations, preparation protocols, deposition protocols, curing protocols, and defined use conditions. More specifically, the invention relates to the formation of durable protective surfaces on solid substratesthrough the controlled arrangement of defined material classes within a single coating region or distributed across multiple coating regions.

[0045] The coating architecture is configured as a single layer embodiment, a multilayer embodiment, or an optional primer assisted embodiment. The system is defined by structural allocation of interfacial function, reinforcement function, network function, surface energy function, and protective outer surface function. The disclosed compositions are configured to generate hydrophobic behavior, self cleaning behavior, chemical resistance, fouling resistance, scaling resistance, and environmental durability across a broad range of substrates.

[0046] Coating Ontology and System Architecture

[0047] The invention provides a modular coating system disposed on a substrate (101, 201, 301, 401). The substrate (101, 201, 301, 401) defines the underlying solid article or article surface that receives the coating system. The coating system comprises at least one coating region and an optional primer layer (102, 202, 402).

[0048] When present, the optional primer layer (102, 202, 402) occupies an interfacial position between the substrate (101, 201, 301, 401) and an overlying coating region. The primer layer (102, 202, 402) provides substrate coupling, coating attachment, interfacial stabilization, adhesion retention, and improved coating coverage.

[0049] In one embodiment, the coating system is configured as a single layer architecture consisting of one integrated coating region (302) disposed directly on the substrate (301) or on the optional primer layer (102, 202, 402). In this single layer embodiment, multiple functional constituents are integrated within one continuous region (302) to perform adhesion related function, structural function, network forming function, low surface energy function, and protective surface function within a single coating body. In another embodiment, the coating system is configured as a multilayer architecture comprising at least a base region (103, 203, 403) and an outer region (104, 204, 404). The base region (103, 203, 403) occupies a position between the substrate (101, 201,401), or the optional primer layer (102, 202, 402), and the outer region (104, 204, 404). The base region (103, 203, 403) is configured to provide film formation, adhesion promotion, interfacial durability, structural reinforcement, anti scaling function, fouling resistance, chemical resistance, and structural support for overlying functionality. The outer region (104, 204, 404) occupies the exposed terminal position of the coating system. The outer region (104, 204, 404) is configured to provide low surface energy surface expression, hydrophobic surface behavior, superhydrophobic surface behavior in selected embodiments, self cleaning behavior, water repellency, reduced wetting, reduced residue retention, reduced fouling, reduced scaling, chemical resistance, and overall protective outer surface performance.

[0050] To achieve the foregoing functional allocation, the coating system comprises coordinated classes of materials. These material classes are selected from film forming adhesion promoting polymeric materials; inorganic particulate structuring, reinforcing, or surface texturing agents; crosslinking, curing, or network forming agents; low surface energy surface forming materials; and one or more organosilicon surface modifying compounds. Depending on the selected architectural embodiment, these material classes may be integrated into a single continuous coating region (302) or distributed structurally across two or more discrete coating regions, including the base region (103, 203, 403) and the outer region (104, 204, 404).

[0051] The invention accordingly defines a modular coating architecture characterized by defined structural roles, positional relationships, coordinated material classes, and protective functions.

[0052] Substrate Classes

[0053] The disclosed protective coating system is configured for formation on multiple classes of solid substrates (101, 201, 301, 401) characterized by diverse compositions, morphologies, geometries, compliances, thermal tolerances, and surface conditions.In various embodiments, the substrate (101, 201, 301, 401) comprises a metallic material, a ceramic material, a polymeric material, a composite material, or a mixed material assembly. The substrate (101, 201, 301, 401) may comprise a metallic material selected from a pure metal, a metal alloy, stainless steel, aluminum, galvanized metal, coated metal, painted metal, and metal containing assemblies. The substrate (101, 201, 301, 401) may comprise a ceramic material selected from ceramic, porcelain, stone, masonry, glass, treated glass, glass ceramic, and mineral based articles. The substrate (101, 201, 301, 401) may comprise a polymeric material selected from an elastomer, a thermoplastic, a thermoset, a coated polymer, a painted polymer, and a polymer containing assembly. The substrate (101, 201, 301, 401) may further comprise a composite material or a mixed material article containing two or more dissimilar substrate classes joined within a single engineered structure.

[0054] The geometry and physical form of the substrate (101, 201, 301, 401) may vary widely. The substrate (101, 201, 301, 401) may present a planar geometry, a curved geometry, a tubular geometry, an internal cavity, or a mesh like configuration. Further, the substrate body and surface may be textured, porous, rigid, flexible, or heat sensitive. The coating system is equally applicable to virgin surfaces, pre coated surfaces, pre painted surfaces, and chemically treated surfaces.

[0055] Representative substrates (101, 201, 301, 401) include, but are not limited to, metal panels, process equipment surfaces, stainless steel articles, aluminum articles, glass articles, polymer housings, ceramic articles, composite enclosures, flexible sheets, elastomeric surfaces, and mixed material assemblies. The foregoing substrate classes define the intended breadth of substrate applicability. These classes further establish the physical context guiding the selection of optional primer use, layer architecture, cure conditions, coating thickness, deposition mode, and surface preparation.

[0056] Substrate classification within the present invention is determined by material class, surface condition, geometric form, mechanical compliance, thermal sensitivity, and defined service exposure. Accordingly, the applicability of the coating system isexpressly not limited to a single substrate chemistry, a single article geometry, or a single use environment.

[0057] Primer Embodiments

[0058] In certain embodiments, the protective coating system includes an optional primer layer (102, 202, 402) disposed between the substrate (101, 201, 301, 401) and an overlying coating region. The primer layer (102, 202, 402) defines an interfacial modification region configured to improve substrate wetting, substrate coupling, coating attachment, coverage uniformity, adhesion retention, and interfacial durability. The primer layer (102, 202, 402) may be continuous or discontinuous and may cover all or a portion of the treated surface.

[0059] Structurally, the primer layer (102, 202, 402) comprises a silane coupling agent and an inorganic particulate component. In some embodiments, the primer layer (102, 202, 402) may further comprise an acid catalyst and a solvent or carrier medium.

[0060] The silane coupling agent comprises one or more organosilane compounds capable of chemical interaction with the substrate surface (101, 201, 301, 401), the overlying coating region, or both. The organosilane compound may include functional groups selected from epoxy functionality, alkoxy functionality, hydrolyzable silane functionality, and combinations thereof. In a preferred embodiment, the silane coupling agent comprises glycidoxypropyltrimethoxysilane.

[0061] The inorganic particulate component comprises an inorganic oxide particulate material. The inorganic particulate component may be selected from colloidal silica, nano silica, and combinations thereof. In certain aspects, the inorganic particulate component comprises a silica containing dispersion configured to provide interfacial reinforcement and coupling site generation.

[0062] A preferred primer composition comprises glycidoxypropyltrimethoxysilane, colloidal silica, an acid catalyst, and an alcohol / water carrier medium. This coordinated composition provides a hydrolyzable organosilane phase, a silica containing inorganicinterfacial phase, acid promoted condensation conditions, and a carrier system configured for deposition as a thin interfacial layer forming the primer layer (102, 202, 402).

[0063] The primer layer (102, 202, 402) may be deposited by operations including, but not limited to, spraying, brushing, wiping, dipping, flow coating, or other deposition operations configured to produce an interfacial film on the substrate (101, 201, 301, 401). Following deposition, the primer layer (102, 202, 402) may be dried, set, or partially cured prior to the formation of the overlying coating region thereon.

[0064] The primer layer (102, 202, 402) accordingly defines an interfacial embodiment of the invention, wherein the primer layer (102, 202, 402) does not constitute the entire protective architecture. The primer layer (102, 202, 402) defines a substrate coupling region that supports subsequent formation of the base region (103, 203, 403), the single integrated coating region (302), the outer protective region (104, 204, 404), or combinations thereof.

[0065] Single Laver Embodiments

[0066] In certain embodiments, the coating architecture is configured as a single layer embodiment comprising one multifunctional coating region (302) disposed on the substrate (301) or on an optional primer layer (102, 202, 402). The single coating region (302) defines an integrated structural body configured to perform interfacial function, film forming function, reinforcement function, network forming function, low surface energy surface function, and protective surface function within one continuous layer. Compositionally, the single coating region (302) comprises coordinated classes of materials, including: one or more film forming adhesion promoting polymeric materials; one or more inorganic particulate structuring, reinforcing, or surface texturing agents; one or more crosslinking, curing, or network forming agents; one or more low surface energy surface forming materials; and one or more organosilicon surface modifying compounds.Within this integrated architecture, the respective material classes are selected to perform defined technical roles. Specifically, the film forming polymeric material is configured to provide layer continuity, substrate attachment, cohesion, and mechanical integrity. The inorganic particulate agent is configured to provide structuring, reinforcement, surface texturing, and internal surface area contributions. The crosslinking, curing, or network forming agent is configured to provide internal network development, dimensional stabilization, cohesion enhancement, and resistance to disruption under service exposure. The low surface energy material is configured to reduce surface free energy at the exposed boundary of the coating region (302), while the organosilicon surface modifying compound is configured to provide surface active modification, interphase compatibility, low energy surface expression, and optional coupling contributions.

[0067] In certain embodiments, the single layer embodiment may exhibit compositional stratification within the thickness of the coating region (302). For example, an upper portion of the coating region (302) may comprise a higher concentration of the low surface energy constituents, the organosilicon constituents, or both. Conversely, a lower portion of the coating region (302) may comprise a higher concentration of the film forming polymeric material, the inorganic particulate material, the network forming material, or combinations thereof. The presence or absence of such stratification does not alter the classification of the embodiment as a single layer system, provided that the coating defines one continuous, integrated region (302) rather than discrete superposed layers.

[0068] The single layer embodiment provides a reduced step architectural form suitable for deployment where simplified processing is desired. Accordingly, the single layer embodiment is compatible with one step applications, reduced step applications, field deployments, retrofit uses, geometrically complex substrates, and applications requiring a reduced total coating thickness. The single layer embodiment is compatible with multiple deposition modes, provided that the resulting coating comprises oneintegrated multifunctional region (302) incorporating the material classes recited herein.

[0069] Multilayer Embodiments

[0070] In certain embodiments, the coating architecture is configured as a multilayer embodiment comprising two or more discrete coating regions arranged in superposed relation on a substrate (101, 201, 401) or on an optional primer layer (102, 202, 402). The multilayer embodiment comprises at least a base layer or base region (103, 203, 403) and an outer layer or outer region (104, 204, 404). In certain embodiments, the multilayer embodiment further comprises a primer layer (102, 202, 402) located between the substrate (101, 201, 401) and the base layer (103, 203, 403), and defines a primer / base / outer configuration or, alternatively, a base / outer configuration where the primer is omitted.

[0071] The base layer (103, 203, 403) occupies the interfacial position of the multilayer coating system and is formed prior to the formation of the outer layer (104, 204, 404). The base layer (103, 203, 403) is configured to provide substrate attachment, primer compatibility, particle anchoring, film continuity, structural support, interfacial durability, and support for overlying layer formation. Where such function is imparted by specific composition selection, the base layer (103, 203, 403) may further be configured to provide anti scaling function, fouling resistance, chemical resistance, or combinations thereof.

[0072] The outer layer (104, 204, 404) occupies the exposed terminal position of the multilayer coating system and is formed over the base layer (103, 203, 403). The outer layer (104, 204, 404) constitutes the surface region presented to the service environment. Accordingly, the outer layer (104, 204, 404) is configured to provide low surface energy surface expression, hydrophobicity, superhydrophobic surface behavior in selected embodiments, self cleaning behavior, reduced liquid retention, anti foulingbehavior, resistance to wetting, resistance to residue deposition, and protective outer surface performance.

[0073] Compositionally, the base layer (103, 203, 403) and the outer layer (104, 204, 404) may be chemically distinct, or they may share one or more constituents. The presence of shared constituents does not alter the classification of the coating as a multilayer embodiment, provided that discrete superposed regions remain structurally present. Functional differentiation between the base layer (103, 203, 403) and the outer layer (104, 204, 404) constitutes a characteristic feature of the multilayer embodiment, wherein the base layer (103, 203, 403) is configured to perform predominantly interfacial and structural functions, and the outer layer (104, 204, 404) is configured to perform predominantly low surface energy and protective surface functions.

[0074] The multilayer embodiment provides a modular coating architecture particularly suited to service conditions requiring enhanced interfacial bonding, greater mechanical durability, wider substrate adaptability, and operation under severe service exposure. The multilayer embodiment separates interfacial function from exposed surface function, permitting an architecture in which the interfacial region may be optimized independently of the outer protective region (104, 204, 404) through independent composition selection, independent deposition, independent partial or full curing, and independent thickness selection.

[0075] The multilayer embodiment accordingly defines a structurally differentiated coating system. It differs from the single layer embodiment by the presence of discrete, superposed coating regions characterized by distinct positional identities, distinct functional roles, and optional compositional distinctions.

[0076] Composition Families

[0077] Unless expressly stated otherwise, all percentages set out in this section are expressed on a total non volatile solids basis of the relevant coating composition. In certain embodiments, the coating architecture comprises coordinated material classes assignedto defined structural roles. A given constituent may perform more than one functional role within the coating composition, depending on formulation context, layer position, and curing conditions. The invention is not limited to a single molecular species, a single solvent system, or a single deposition route.

[0078] Film Forming Adhesion Promoting Polymeric Materials

[0079] The film forming adhesion promoting polymeric material is configured to constitute the continuous or substantially continuous matrix of the base layer (103, 203, 403), the single layer embodiment (302), or both. The film forming adhesion promoting polymeric material may be selected from naturally derived biopolymers, polysaccharides, semi synthetic polymers, synthetic polymers, water dispersible polymers, solvent borne polymers, and combinations thereof, provided that the selected material is capable of film formation and adhesion promotion within the disclosed coating architecture.

[0080] Representative polymeric materials include chitosan, chitin, cellulose, cellulose derivatives, starch, starch derivatives, alginate, pectin, dextran, pullulan, lignin, naturally derived polymer blends, and combinations thereof. In preferred embodiments, the polymeric material comprises chitosan. In further preferred embodiments, the biopolymeric system comprises chitosan used alone or in combination with polyacrylic acid, lignin, cellulose derived reinforcement, or combinations thereof.

[0081] The film forming adhesion promoting polymeric material may be present in an amount from 5 to 50 wt% of the total solids of the relevant coating composition. A preferred range is from 10 to 40 wt%. A more preferred range for a base layer composition is from 15 to 40 wt%. Where chitosan is present, a preferred range is from 10 to 35 wt%, and a more preferred range is from 15 to 30 wt%. Where polyacrylic acid is present as a co binder, dispersant, network assisting constituent, or combinations thereof, a preferred range is from 0.5 to 15 wt%, and a more preferred range is from 1 to 10 wt%.Where lignin, a cellulose derivative, a starch derivative, alginate, pectin, dextran, or pullulan is present as a partial substitute for chitosan or as a supplemental naturally derived polymeric constituent, a preferred range is from 1 to 30 wt%, and a more preferred range is from 3 to 20 wt%.

[0082] Inorganic Particulate Structuring Agents

[0083] The inorganic particulate structuring agent is configured to provide reinforcement, internal surface area, roughness generation, surface texturing contribution, particle anchoring, interfacial support, outer surface topography development, or combinations thereof. The inorganic particulate structuring agent may be selected from silica, nano silica, colloidal silica, alumina, titania, zirconia, silicates, mixed oxides, photocatalytic oxides, and combinations thereof. In preferred embodiments, the particulate system comprises silica, nano silica, colloidal silica, hydrophobic fumed silica, alkyl grafted silica, or combinations thereof. Optional titania may be included where photocatalytic associated function or antimicrobial associated function is desired.

[0084] The inorganic particulate structuring agent may be present in an amount from 1 to 45 wt% of the total solids of the relevant coating composition. A preferred range is from 5 to 35 wt%. A more preferred range for a base layer composition is from 10 to 35 wt%. A more preferred range for an outer layer composition is from 3 to 25 wt%. A preferred range for colloidal silica or nano silica in a primer composition forming the primer layer 102, 202, 402 is from 20 to 60 wt% of primer solids, and a more preferred range is from 25 to 50 wt%. A preferred range for hydrophobic fumed silica or alkyl grafted silica in an outer layer composition forming the outer region 104, 204, 404 is from 3 to 25 wt%, and a more preferred range is from 5 to 18 wt%. A preferred range for titanium dioxide, when present as an optional additive, is from 0.5 to 15 wt%, and a more preferred range is from 1 to 10 wt%.

[0085] The inorganic particulate agent may have an average particle size in the nanometer range, the submicron range, the micron range, or combinations thereof. A preferrednano silica size range is from 5 to 200 nm, and a more preferred range is from 10 to 100 nm. A preferred colloidal silica size range is from 10 to 80 nm. A preferred hydrophobic fumed silica size range is from 5 to 100 nm.

[0086] Crosslinking, Curing, and Network Forming Agents

[0087] The crosslinking, curing, or network forming agent is configured to provide internal cohesion, matrix stabilization, acid mediated crosslink development, hydrogen bond reinforcement, ionic interaction, esterification potential, condensation promotion, or combinations thereof. The crosslinking or network forming agent may be selected from organic acids, polyfunctional organic acids, polycarboxylic acids, acid catalysts, multifunctional crosslinkers, condensation promoting agents, network forming additives, and combinations thereof.

[0088] Representative materials include citric acid, phytic acid, tartaric acid, malic acid, succinic acid, polyacrylic acid, multifunctional acids capable of promoting crosslinking or network formation, and combinations thereof. In preferred embodiments, the crosslinking or network forming agent comprises citric acid. In further preferred embodiments, the acid system comprises citric acid used alone or in combination with phytic acid.

[0089] The crosslinking, curing, or network forming agent may be present in an amount from 0.1 to 20 wt% of the total solids of the relevant coating composition. A preferred range is from 0.5 to 12 wt%. A more preferred range for a base layer composition is from 1 to 12 wt%. A preferred range for citric acid is from 1 to 12 wt%, and a more preferred range is from 2 to 8 wt%. A preferred range for phytic acid, when present, is from 0.5 to 10 wt%, and a more preferred range is from 1 to 5 wt%. A preferred range for an acid catalyst in a primer composition forming the primer layer 102, 202, 402 is from 0.05 to 3 wt% of primer solids, and a more preferred range is from 0.1 to 1.5 wt%.

[0090] Low Surface Energy Surface Forming MaterialsThe low surface energy surface forming material is configured to provide exposed surface wetting resistance, reduced surface free energy, droplet mobility, residue release behavior, outer layer continuity, or combinations thereof. The low surface energy surface forming material may be selected from siloxane containing materials, polysiloxanes, organosiloxanes, silicone materials, silicone oils, curable siloxanes, hydrophobic oligomers, hydrophobic polymers, hydrophobic wax like materials, and combinations thereof. In preferred embodiments, the low surface energy material comprises polydimethylsiloxane.

[0091] The low surface energy surface forming material may be present in an amount from 5 to 70 wt% of the total solids of the relevant coating composition. A preferred range is from 15 to 60 wt%. A more preferred range for an outer layer composition forming the outer region 104, 204, 404 is from 20 to 65 wt%. A preferred range for polydimethylsiloxane in an outer layer composition is from 20 to 65 wt% of outer layer solids, and a more preferred range is from 30 to 55 wt%.

[0092] Organosilicon Surface Modifying Compounds

[0093] The organosilicon surface modifying compound is configured to provide surface active modification, low energy surface expression, substrate coupling, interphase compatibility, hydrolysis condensation reactivity, or combinations thereof. The organosilicon surface modifying compound may be selected from silanes, siloxanes, alkoxysilanes, epoxy functional silanes, alkyltrialkoxysilanes, organofunctional silanes, and combinations thereof.

[0094] Representative organosilicon compounds include glycidoxypropyltrimethoxysilane, trimethoxy(propyl)silane, methyltriethoxysilane, octyltriethoxysilane, methylethyltriethoxysilane, alkyltrialkoxysilanes of Cl to C12 alkyl chain length, structurally or functionally related silanes or siloxanes capable of surface modification or interphase coupling, and combinations thereof. A preferred primer silane comprises glycidoxypropyltrimethoxysilane. A preferred outer layer silane comprises a non-fluorinated alkyltrialkoxysilane selected from methyltriethoxysilane, octyltriethoxysilane, and combinations thereof.

[0095] The organosilicon surface modifying compound may be present in an amount from 0.1 to 25 wt% of the total solids of the relevant coating composition. A preferred range is from 1 to 15 wt%. A more preferred range for a primer composition is from 10 to 35 wt% of primer solids. A more preferred range for an outer layer composition is from 1 to 15 wt% of outer layer solids. A preferred range for glycidoxypropyltrimethoxysilane in a primer composition is from 10 to 35 wt% of primer solids, and a more preferred range is from 15 to 30 wt%. A preferred range for non-fluorinated alkyl trialkoxysilane in an outer layer composition is from 1 to 15 wt% of outer layer solids, and a more preferred range is from 2 to 10 wt%.

[0096] Optional Additives

[0097] The coating system may further comprise optional additives selected to provide corrosion mitigation, chelation control, antimicrobial associated function, photocatalytic associated function, stabilization, dispersion control, rheology control, foam suppression, surface wetting control, pH adjustment, or combinations thereof. Optional additives are preferably selected such that they do not materially impair formation, continuity, curing, adhesion, or protective function of the coating architecture.

[0098] Representative optional additives include titanium dioxide, photocatalytic oxides, antimicrobial additives, stabilizers, dispersants, rheology modifiers, defoamers, wetting agents, pH modifiers, GLDA, benzotriazole, zinc gluconate, cellulose nanofibers, natural polysaccharide resin, and combinations thereof. Additives such as GLDA, benzotriazole, and zinc gluconate may contribute chelation control, corrosion related control, metal ion interaction, mineral deposition suppression, or combinations thereof, depending on the embodiment. Natural polysaccharide resin may be usedwhere film reinforcement, flexibility, bio based content, or combinations thereof are desired.

[0099] Optional additives may be present individually or collectively in an amount from 0 to 25 wt% of the total solids of the relevant coating composition. A preferred collective range is from 0.1 to 15 wt%, and a more preferred range is from 0.5 to 10 wt%. A preferred range for GLDA, when present, is from 0.1 to 10 wt%. A preferred range for benzotriazole, when present, is from 0.05 to 5 wt%. A preferred range for zinc gluconate, when present, is from 0.05 to 8 wt%. A preferred range for natural polysaccharide resin in an outer layer composition is from 1 to 20 wt%, and a more preferred range is from 3 to 15 wt%.

[0100] Primer, Base Coat, and Top Coat Family Windows

[0101] A preferred primer composition comprises an organosilane coupling agent, a silica containing inorganic particulate, an acid catalyst, and a carrier medium. On a solids basis, the primer composition may comprise 10 to 35 wt% glycidoxypropyltrimethoxysilane, 20 to 60 wt% colloidal silica or nano silica, 0.05 to 3 wt% acid catalyst, and 0 to 10 wt% optional auxiliary additives. On a liquid formulation basis, the primer composition may comprise 2 to 20 wt% total non volatile solids. A preferred liquid formulation solids range is from 5 to 15 wt%. A preferred pH range for the primer composition is from about 3 to about 5.5, and a more preferred range is from about 3.5 to about 5.

[0102] A preferred base coat composition comprises chitosan, nano silica, citric acid, optional polyacrylic acid, optional phytic acid, and optional chelators or corrosion associated additives. On a solids basis, the base coat composition may comprise 10 to 35 wt% chitosan, 10 to 40 wt% nano silica, 1 to 12 wt% citric acid, 0.5 to 15 wt% optional polyacrylic acid, 0.5 to 10 wt% optional phytic acid, 0.1 to 10 wt% optional GLDA, 0.05 to 5 wt% optional benzotriazole, 0.05 to 8 wt% optional zinc gluconate, with the balance comprising additional polymeric material, inorganic particulate material, oroptional additives. On a liquid formulation basis, the base coat composition may comprise 5 to 35 wt% total non volatile solids. A preferred liquid formulation solids range is from 10 to 25 wt%. A preferred pH range for a chitosan containing base coat composition is from about 2.5 to about 6.5, and a more preferred range is from about 3 to about 5.5.

[0103] A preferred outer layer composition comprises polydimethylsiloxane, a non fluorinated organosilicon surface modifying compound, hydrophobic silica, optional titanium dioxide, optional natural polysaccharide resin, and optional citric acid. On a solids basis, the outer layer composition may comprise 20 to 65 wt% polydimethylsiloxane, 1 to 15 wt% non fluorinated alkyltrialkoxysilane, 3 to 25 wt% hydrophobic silica, 0.5 to 15 wt% titanium dioxide, 1 to 20 wt% natural polysaccharide resin, 0 to 8 wt% citric acid, with the balance comprising optional low surface energy materials, optional organosilicon compounds, or optional additives. On a liquid formulation basis, the outer layer composition may comprise 2 to 25 wt% total non volatile solids. A preferred liquid formulation solids range is from 5 to 18 wt%.

[0104] Carrier Systems

[0105] The relevant coating composition may be formulated in an aqueous carrier, an alcohol / water carrier, an organic solvent carrier, or combinations thereof. A preferred primer carrier comprises an ethanol / water mixture, an isopropanol / water mixture, or another alcohol / water carrier system. A preferred base coat carrier comprises water, acidified water, an ethanol / water mixture, or combinations thereof. A preferred outer layer carrier comprises ethanol, isopropanol, ethyl acetate, hexane, or combinations thereof, selected in accordance with compatibility of the low surface energy material and the organosilicon constituents.

[0106] Particle Size WindowsWhere the inorganic particulate component comprises nano silica, a preferred particle size range is from 5 to 200 nm, and a more preferred range is from 10 to 100 nm. Where the inorganic particulate component comprises colloidal silica, a preferred particle size range is from 10 to 80 nm. Where the inorganic particulate component comprises hydrophobic fumed silica, a preferred particle size range is from 5 to 100 nm.

[0107] Coating Thickness Windows

[0108] A preferred dry film thickness for the primer layer 102, 202, 402 is from 0.1 to 10 pm, and a more preferred range is from 0.5 to 5 pm. A preferred dry film thickness for the base layer 103, 203, 403 is from 2 to 60 pm, and a more preferred range is from 5 to 40 pm. A preferred dry film thickness for the outer layer 104, 204, 404 is from 1 to 40 pm, and a more preferred range is from 2 to 25 pm. A preferred total dry film thickness for a multilayer coating system is from 5 to 100 pm, and a more preferred range is from 10 to 60 pm. A preferred dry film thickness for a single layer embodiment 302 is from 2 to 80 pm, and a more preferred range is from 5 to 50 pm.

[0109] The foregoing composition family ranges define the formulation space for primer embodiments, base coat embodiments, top coat embodiments, single layer embodiments, and multilayer embodiments of the invention.

[0110] Preparation Methods

[0111] In certain embodiments, the coating compositions are prepared by controlled liquid phase processing selected from solution processing, dispersion processing, suspension processing, emulsion processing, and combinations thereof. The selection of the processing route is selected in accordance with constituent solubility, constituent dispersibility, target viscosity, target solids content, target coating architecture, and the intended deposition method.

[0112] Preparation typically begins with the selection of a carrier system. The carrier system may be selected from an aqueous carrier, an alcohol / water carrier, an organic solventcarrier, and combinations thereof. The carrier system is charged to a mixing vessel, whereupon agitation is initiated. The temperature may be maintained at ambient conditions or at a controlled elevated condition compatible with the chemistry under preparation.

[0113] In an exemplary preparation sequence, where the formulation contains a film forming adhesion promoting polymeric material as a matrix forming constituent, the polymeric material is dissolved or dispersed first. Processes selected from hydration, dissolution, swelling, dispersion, and combinations thereof are allowed to proceed until a uniform liquid phase or a substantially uniform dispersed phase is obtained. Where the formulation is a polymer containing system, a crosslinking agent, curing agent, network forming agent, or combinations thereof may be introduced following the establishment of the polymeric phase. Further, an inorganic particulate structuring agent is introduced after the establishment of the polymeric phase and the crosslinking or network forming constituent, except in embodiments where particulate pre dispersion is desired for stability or particle deagglomeration. Low surface energy constituents are introduced after the establishment of the matrix phase or at a later stage selected to preserve phase stability. Organosilicon surface modifying compounds may be introduced at a stage compatible with hydrolysis, condensation, coupling, dispersion stability, and target deposition behavior.

[0114] Depending on the intended application, the preparation sequence may further include adjustments selected from viscosity adjustment, pH adjustment, solids content adjustment, dispersion stability adjustment, and combinations thereof. To achieve the desired uniform dispersion, the preparation sequence may optionally include operations selected from sonication, high shear mixing, low shear mixing, aging, filtration, degassing, and combinations thereof. Where the intended architecture defines a multilayer system comprising a primer layer 102, 202, 402, a base layer 103, 203, 403, an outer layer 104, 204, 404, or combinations thereof, separate coating compositions may be prepared for the respective discrete coating regions.Primer Composition Preparation

[0115] In an exemplary method, a primer composition is prepared by charging an alcohol / water carrier system to a mixing vessel. A silane coupling agent may then be introduced under agitation. Hydrolysis is permitted to proceed for a controlled period. An acid catalyst may be introduced before, during, or after silane addition, provided that a hydrolyzable and coatable primer composition is obtained. A silica containing inorganic particulate component is then introduced under agitation. The silica containing component may be selected from colloidal silica, nano silica, and combinations thereof. Mixing is continued until a substantially homogeneous primer composition is obtained. Filtration may be performed where particulate oversize removal is required. Degassing may be performed where entrained air is present. A preferred primer preparation utilizes glycidoxypropyltrimethoxysilane as the silane coupling agent, colloidal silica or nano silica as the inorganic particulate component, an acid catalyst, and an ethanol / water carrier. In preferred embodiments, the primer composition comprises 10 to 35 wt% glycidoxypropyltrimethoxysilane, 20 to 60 wt% colloidal silica or nano silica, and 0.05 to 3 wt% acid catalyst, based on total primer solids. The primer composition may be aged for 5 minutes to 24 hours before deposition. A preferred aging interval is from 15 minutes to 4 hours.

[0116] Base Laver Composition Preparation

[0117] In an exemplary method, a base layer composition is prepared by charging a carrier selected from an aqueous carrier, an acidified aqueous carrier, an alcohol / water carrier, and combinations thereof, to a mixing vessel. A film forming adhesion promoting polymeric material is preferably introduced first. Where chitosan is employed, the carrier is adjusted to an acidic condition sufficient to solubilize or disperse the chitosan. Mixing is continued until a uniform polymer phase is obtained. A crosslinking or network forming agent is then introduced. An inorganic particulate structuring agent is introduced thereafter under agitation, sonication, or both, sufficient to reduceagglomeration and establish a coatable composition. Optional constituents selected from co binders, dispersants, chelators, corrosion associated additives, pH modifiers, stabilizers, and combinations thereof, may be added after the establishment of the main polymer or particulate phase or at any stage compatible with compositional stability. A preferred base layer preparation utilizes chitosan as the film forming adhesion promoting polymeric material, nano silica as the inorganic particulate structuring agent, and citric acid as the crosslinking or network forming agent. In preferred embodiments, the base layer composition comprises 10 to 35 wt% chitosan, 10 to 40 wt% nano silica, and 1 to 12 wt% citric acid, based on total base layer solids. Polyacrylic acid may be introduced as a supplemental co binder, dispersant, or network assisting constituent. Phytic acid may be introduced as an optional co crosslinking constituent. Additives such as GLDA, benzotriazole, and zinc gluconate may be introduced where chelation, corrosion related control, or mineral deposition suppression are desired. Mixing is continued until a substantially uniform and coatable dispersion or solution is obtained. Filtration may be performed where particle size control is desired. Degassing may be performed before deposition.

[0118] Outer Laver Composition Preparation

[0119] In an exemplary method, an outer layer composition is prepared by charging a carrier selected from an organic carrier, an alcohol carrier, and combinations thereof, to a mixing vessel. A low surface energy surface forming material is preferably introduced first where the material is soluble or dispersible in the selected carrier. Organosilicon surface modifying compounds are introduced thereafter under agitation. Inorganic particulate constituents selected for roughness generation, reinforcement, photocatalytic associated function, or combinations thereof, are introduced subsequently. Mixing, sonication, or both are continued until a stable and coatable outer layer composition is obtained.A preferred outer layer preparation utilizes polydimethylsiloxane as the low surface energy surface forming material. A preferred organosilicon constituent comprises one or more non fluorinated silanes or siloxanes. A preferred particulate constituent comprises hydrophobic silica, hydrophobic fumed silica, alkyl grafted silica, and optionally titanium dioxide. In preferred embodiments, the outer layer composition comprises 20 to 65 wt% polydimethylsiloxane, 1 to 15 wt% non fluorinated alkyltrialkoxysilane, and 3 to 25 wt% hydrophobic silica, based on total outer layer solids. A natural polysaccharide resin may be introduced as a supplemental film reinforcing constituent. Citric acid may be introduced where cohesion enhancement or interphase interaction is desired. Filtration may be performed where particle oversize removal is required. Degassing may be performed prior to deposition.

[0120] Single Laver Composition Preparation

[0121] In an exemplary method, a single layer multifunctional composition is prepared by establishing a film forming polymeric phase in a selected carrier system, introducing a crosslinking or network forming constituent, introducing an inorganic particulate structuring constituent under agitation or sonication sufficient for dispersion control, introducing a low surface energy constituent, introducing an organosilicon surface modifying constituent, and executing adjustments selected from viscosity, pH, solids content, and combinations thereof, to a level suitable for the selected deposition process. The order of addition may be modified where stability, hydrolysis control, phase compatibility, or target stratification behavior require a different sequence. The resulting composition remains within the scope of the invention provided that the deposited material forms one integrated coating region 302 containing the recited functional material classes.

[0122] Mixing Conditions, Aging, Filtration, DegassingMixing may be performed under conditions selected from low shear, medium shear, high shear, and combinations thereof. Sonication may be utilized during operations selected from particulate incorporation, deagglomeration, final homogenization, and combinations thereof. Aging may be employed to facilitate mechanisms selected from hydrolysis, condensation, solvation, hydrogen bond development, viscosity stabilization, and combinations thereof. Filtration may be used to remove oversized particles, gels, or foreign matter. Degassing may be used to remove entrained air or volatile inclusions prior to deposition.

[0123] Aging intervals may range from 5 minutes to 48 hours depending on the composition under preparation. A preferred aging interval for primer compositions is from 15 minutes to 4 hours. A preferred aging interval for base layer compositions is from 15 minutes to 12 hours. A preferred aging interval for outer layer compositions is from 5 minutes to 6 hours. Filtration may be carried out through a nominal pore size of 0.2 micrometers to 200 micrometers, selected in accordance with the particulate size distribution of the formulation. A preferred filtration range is from 1 micrometer to 50 micrometers for primer and outer layer formulations containing fine particulate. Degassing may be carried out under operations selected from vacuum, standing, centrifugal treatment, and combinations thereof.

[0124] Solids Content during Preparation

[0125] The total non volatile solids content of the primer composition during preparation may range from 2 to 20 wt% on a liquid formulation basis. A preferred primer solids range is from 5 to 15 wt%. The total non volatile solids content of the base layer composition during preparation may range from 5 to 35 wt%. A preferred base layer solids range is from 10 to 25 wt%. The total non volatile solids content of the outer layer composition during preparation may range from 2 to 25 wt%. A preferred outer layer solids range is from 5 to 18 wt%. The total non volatile solids content of a single layermultifunctional composition may range from 5 to 25 wt%. A preferred single layer solids range is from 8 to 20 wt%.

[0126] pH Control

[0127] The pH of a polymer containing base layer composition may be adjusted to maintain polymer solubilization, dispersion stability, crosslinking control, and deposition suitability. Where chitosan is employed, the pH is maintained in an acidic range sufficient for chitosan solubilization or stable dispersion. A preferred pH range for a chitosan containing base layer composition is from about 2.5 to about 6.5, and a more preferred range is from about 3.0 to about 5.5. A primer composition containing a hydrolyzable silane may be maintained at an acidic pH suitable for controlled silane hydrolysis and condensation. A preferred primer pH range is from about 3.0 to about 5.5, and a more preferred range is from about 3.5 to about 5.0.

[0128] The preparation methods set out in this section define operative process windows for the generation of primer compositions, base layer compositions, outer layer compositions, and single layer multifunctional compositions suitable for the formation of the coating architectures described herein.

[0129] Application Methods

[0130] In certain embodiments, formation of the coating system is carried out by a deposition operation selected to produce the intended coating region, coating stack, thickness, continuity, surface coverage, and functional allocation. The deposition operation is selected in accordance with substrate class 601, substrate geometry, formulation rheology, solids content, volatility of the carrier system, desired dry film thickness, and intended service function.

[0131] Permissible deposition operations are selected from spraying, dip coating, brushing, wiping, rolling, flow coating, spin coating, casting, slot die coating, electrostatic application, and combinations thereof. Selection among these deposition operations ismade on the basis of controllability of film formation, uniformity of coverage, compatibility with the formulation, compatibility with the substrate, and compatibility with the intended scale of use.

[0132] Spray deposition is suitable for planar substrates, curved substrates, mixed geometry articles, field applications, retrofit applications, and large area applications. Dip coating is suitable for articles capable of immersion, internal or external surface coverage, and repeatable thickness development through withdrawal control. Brushing, wiping, and rolling are suitable for maintenance operations, localized treatment, field deployments, and geometrically constrained surfaces. Flow coating, casting, slot die coating, and spin coating are suitable for controlled laboratory deposition, manufacturing deposition, and thickness controlled deposition. Electrostatic application is suitable where charge assisted deposition improves transfer efficiency or coverage.

[0133] The coating system may be deposited as a primer assisted multilayer architecture. In such an exemplary embodiment, the primer layer 503 is preferably applied first. The primer layer 503 may then be dried, set, or partially cured to a condition sufficient for the acceptance of an overlying coating region. The base layer corresponding to base region 103, 203, 403 may subsequently be applied over the primer layer 503. The base layer is then preferably dried, set, or partially cured to a condition sufficient for the formation of the outer layer corresponding to outer region 104, 204, 404. The outer layer may subsequently be applied over the base layer. The resulting coating system may then be subjected to operations selected from final drying, final setting, final curing, and combinations thereof.

[0134] The coating system may also be deposited as a multilayer architecture without a primer layer. In such an embodiment, the base layer is preferably applied directly to the substrate 501. The base layer may be dried, set, or partially cured prior to the application of the outer layer. Final conversion of the coating system is then performed. The coating system may further be deposited as a single layer embodiment. In such an embodiment, one integrated multifunctional coating composition is applied directly tothe substrate 501 or to the optional primer layer 503. Application may occur in one pass, or application may occur in multiple passes. Multiple pass application remains within the scope of the single layer embodiment, provided that the deposited material forms one integrated coating region 505 after drying, setting, curing, or combinations thereof.

[0135] Application may be controlled by parameters selected from wet film thickness, deposition rate, number of passes, inter pass interval, withdrawal speed, atomization condition, spray distance, substrate orientation, and combinations thereof. The selected parameters are adjusted to obtain continuous coverage, the absence of macroscopic voids, the absence of unacceptable flow defects, acceptable edge coverage, acceptable adhesion, and acceptable final thickness. Wet film thickness targets are selected to achieve the intended dry film windows depending on formulation solids content and deposition efficiency.

[0136] A primer composition may be applied at a wet film thickness from 2 to 100 micrometers. A preferred wet film thickness range for the primer composition is from 5 to 50 micrometers. A preferred dry film thickness range for the primer layer 102, 202, 402, 503 is from 0.1 to 10 micrometers, and a more preferred dry film thickness range is from 0.5 to 5 micrometers.

[0137] A base layer composition may be applied at a wet film thickness from 10 to 300 micrometers. A preferred wet film thickness range for the base layer composition is from 20 to 150 micrometers. A preferred dry film thickness range for the base layer 103, 203, 403, 506 is from 2 to 60 micrometers, and a more preferred dry film thickness range is from 5 to 40 micrometers.

[0138] An outer layer composition may be applied at a wet film thickness from 5 to 200 micrometers. A preferred wet film thickness range for the outer layer composition is from 10 to 100 micrometers. A preferred dry film thickness range for the outer layer 104, 204, 404, 506 is from 1 to 40 micrometers, and a more preferred dry film thickness range is from 2 to 25 micrometers.A single layer multifunctional composition may be applied at a wet film thickness from 10 to 300 micrometers. A preferred wet film thickness range for the single layer composition is from 20 to 150 micrometers. A preferred dry film thickness range for the single integrated coating region 302, 505 is from 2 to 80 micrometers, and a more preferred dry film thickness range is from 5 to 50 micrometers.

[0139] The total dry film thickness of a primer / base / outer multilayer coating system may range from 5 to 100 micrometers. A preferred total dry film thickness range is from 5 to 80 micrometers, and a more preferred total dry film thickness range is from 10 to 60 micrometers.

[0140] The intercoat interval is selected in accordance with requirements for solvent removal, water removal, condensation progress, partial cure development, handling stability, or combinations thereof. The intercoat interval may range from 1 minute to 24 hours. A preferred intercoat interval range is from 5 minutes to 6 hours, and a more preferred range is from 10 minutes to 2 hours.

[0141] The substrate 501 may optionally undergo surface preparation 502 prior to deposition. Surface preparation operations may be selected from cleaning, degreasing, washing, drying, solvent wiping, abrasion, activation, pretreatment, and combinations thereof. Surface preparation is typically selected in accordance with the chemistry of the substrate 501, the contamination state of the substrate 501, and the intended coating architecture.

[0142] The application methods set out in this section define operative deposition routes for primer embodiments, single layer embodiments, multilayer embodiments, and coated article embodiments within the scope of the invention.

[0143] Curing Methods

[0144] Conversion of the deposited coating composition into the final coating system proceeds by one or more mechanisms selected from solvent removal, water removal, drying, setting, condensation, moisture assisted conversion, thermal curing, crosslinkdevelopment, network formation, and combinations thereof. The desired conversion route is selected in accordance with the coating architecture, composition class, carrier system, substrate tolerance, and target service properties.

[0145] Curing or setting may be carried out under ambient conditions or low elevated temperature conditions. In certain embodiments, the final curing temperature is maintained at a value not exceeding about 80°C. A preferred curing temperature range is from about 20°C to about 80°C, and a more preferred curing temperature range is from about 25 °C to about 60°C. An ambient cure embodiment comprises curing or setting at a temperature from about 20°C to about 35 °C. A low elevated temperature embodiment comprises curing or setting at a temperature from about 35°C to about 80°C.

[0146] The primer layer 102, 202, 402, 503 may be dried, set, or partially cured prior to the formation of an overlying coating region. A preferred primer drying or setting interval is from about 1 minute to about 24 hours, and a more preferred interval is from about 5 minutes to about 6 hours. A preferred primer conversion temperature is from about 20°C to about 50°C, and a more preferred primer conversion temperature is from about 25°C to about 50°C.

[0147] The base layer 103, 203, 403, 506 may be dried, set, partially cured, or fully cured prior to the application of the outer layer 104, 204, 404, 506. The selected condition is determined by desired interlayer bonding, solvent or water removal, network development, and handling stability. A preferred base layer drying or setting interval prior to outer layer application is from about 5 minutes to about 24 hours, and a more preferred interval is from about 10 minutes to about 8 hours. A preferred base layer conversion temperature is from about 20°C to about 80°C, and a more preferred base layer conversion temperature is from about 25 °C to about 60°C.

[0148] The outer layer 104, 204, 404, 506 may be dried, set, or cured after deposition on the base layer 103, 203, 403, 506, or directly on the substrate or primer in a single layer embodiment. Final conversion of the outer layer 104, 204, 404, 506 may occurindependently, or it may occur simultaneously with the continued conversion of an underlying region in a co curing mode. A preferred outer layer conversion interval is from about 10 minutes to about 48 hours, and a more preferred interval is from about 30 minutes to about 24 hours. A preferred outer layer conversion temperature is from about 20°C to about 80°C, and a more preferred outer layer conversion temperature is from about 25°C to about 60°C.

[0149] A single layer embodiment 302, 505 may be dried, set, partially cured, or fully cured after one pass deposition or after multi pass deposition. A preferred conversion interval for a single layer embodiment is from about 10 minutes to about 48 hours, and a more preferred interval is from about 30 minutes to about 24 hours. A preferred conversion temperature is from about 20 °C to about 80 °C, and a more preferred conversion temperature is from about 25 °C to about 60°C.

[0150] Multilayer curing may be carried out by any of three principal routes. A first route comprises the full cure of each layer prior to the formation of the subsequent layer. A second route comprises the partial cure of a lower layer prior to the formation of the subsequent layer. A third route comprises the sequential application of two or more layers followed by joint final curing, namely co curing. Each route remains within the scope of the invention provided that the intended layer identity, interfacial attachment, and protective surface function are preserved in the final coating system.

[0151] Partial cure denotes a conversion state sufficient to maintain coating continuity and coating placement while retaining residual reactivity, residual interdiffusion capacity, residual interfacial compatibility, or combinations thereof. Full cure denotes a conversion state sufficient to provide final or substantially final network development and handling stability under intended service conditions.

[0152] Ambient or low temperature curing provides technical utility in applications including, but not limited to, field application, retrofit application, mitigation of thermal burden on the substrate, mitigation of thermal burden on installed infrastructure, compatibility with heat sensitive substrates, lower process energy demand, and reduced downtime.Moisture assisted conversion may occur in embodiments containing hydrolyzable silanes, siloxane precursors, condensation reactive organosilicon constituents, or combinations thereof. Acid assisted conversion may occur in embodiments containing acid promoted hydrolysis or condensation chemistry. Thermal assistance may be utilized to accelerate mechanisms selected from solvent removal, water removal, silane condensation, acid mediated network development, polymer film consolidation, and combinations thereof.

[0153] A preferred curing schedule for a primer assisted multilayer embodiment comprises: primer deposition; primer drying or partial cure at about 20°C to about 50°C for about 5 minutes to about 4 hours; base layer deposition; base layer drying or partial cure at about 20°C to about 60°C for about 10 minutes to about 8 hours; outer layer deposition; and final cure at about 20°C to about 80°C for about 30 minutes to about 24 hours. A more preferred final cure comprises heating at about 25°C to about 60°C for about 1 hour to about 12 hours. A preferred thermal cure embodiment comprises heating at about 40°C to about 80°C for about 30 minutes to about 4 hours.

[0154] The curing methods set out in this section define operative conversion windows for primer embodiments, single layer embodiments, multilayer embodiments, preferred low temperature embodiments, and preferred ambient cure embodiments within the scope of the invention.

[0155] Operation and Use

[0156] Upon deposition on a substrate and upon completion of conversion mechanisms selected from drying, setting, curing, condensation, network development, and combinations thereof, the coating system forms a protective surface region having a functional response under service exposure. The functional response may include hydrophobic surface behavior, self cleaning surface behavior, reduced residue retention, anti fouling behavior, anti scaling behavior, chemical resistance, environmental durability, resistance to moisture, resistance to steam, resistance tohumidity, resistance to detergent exposure, resistance to heat exposure, and combinations thereof. These functions may exist individually or in combination. Functional expression is selected in accordance with coating architecture, compositional allocation, thickness, cure condition, substrate class 601, and the intended service environment.

[0157] Hydrophobic surface behavior denotes reduced aqueous wetting at the exposed surface. Self cleaning surface behavior denotes the removal or reduction of particulate matter, liquid borne residue, or surface contamination during contact with moving liquid or during drainage events. Reduced residue retention denotes the reduced persistence of deposits after contact with water, aqueous liquids, cleaning compositions, or contamination sources. Anti fouling behavior denotes reduced accumulation of foreign matter at the exposed surface. Anti scaling behavior denotes reduced formation, reduced persistence, reduced adhesion, or combinations thereof, of mineral or deposit forming species at the coated surface. Chemical resistance denotes the retention of coating continuity, surface function, and structural integrity after contact with selected chemical agents. Environmental durability denotes the retention of coating continuity, interfacial attachment, and surface function under repeated service exposure.

[0158] In certain embodiments, the coating system is configured for use on surfaces exposed to repeated wetting, humidity, moisture, steam, cleaning agents, detergents, thermal cycling, hygiene sensitive conditions, fouling prone environments, or scaling prone environments. The coating system is suitable for service in environments in which conditions selected from liquid exposure, condensate exposure, wash exposure, cleaning exposure, contamination exposure, heat exposure, and combinations thereof occur during normal operation of the coated article (604, 508).

[0159] The coating system may be employed on substrates selected from process surfaces, sanitary surfaces, architectural surfaces, transport related surfaces, equipment surfaces, enclosure surfaces, mixed material assemblies, and other engineered surfaces requiring protective surface performance under operational exposure. Deployment of the coatingsystem is guided by substrate compatibility, service exposure profile, target protective function, and target surface response.

[0160] Operational service of the coating system may comprise conditions selected from direct contact with water, direct contact with aqueous contamination, intermittent contact with steam, intermittent contact with detergent or cleaning compositions, repeated humidity exposure, repeated wet dry cycling, thermal variation, and combinations thereof. Performance under such conditions is dependent upon the structural integrity of the interfacial region, the continuity of the coating body, the stability of the outer surface region, the persistence of low surface energy function, and the resistance of the coating to disruption mechanisms selected from deposition, swelling, dissolution, delamination, cracking, abrasion, and combinations thereof.

[0161] The present section defines the intended operational field of the coating system by service exposure class, by functional response class, and by coated article use condition. The present section does not define the invention by result alone. The invention remains defined by the coating architecture, compositional structure, formation method, and the coated article produced thereby.

[0162] Prophetic Examples

[0163] The following examples define representative embodiments of the invention and outline operative protocols by which a person skilled in the art may practice the invention. Unless expressly identified elsewhere as actual experimental work, the following examples are prophetic. They describe preparation, deposition, curing, and structural outcomes in a technically enabling manner without limiting the broader scope of the disclosure. In selected examples, constituent proportions, curing conditions, and deposition parameters may be selected from the ranges set out elsewhere in this specification.

[0164] Embodiment 1. Primer Assisted Multilayer Coating on Stainless SteelA stainless steel substrate is selected. The substrate surface is cleaned to remove matter selected from grease, particulate contamination, processing residue, loosely bound oxide, and combinations thereof. Cleaning may be carried out by operations selected from detergent washing, solvent wiping, deionized water rinsing, drying, and combinations thereof. A primer composition is prepared comprising glycidoxypropyltrimethoxysilane, colloidal silica or nano silica, an acid catalyst, and an ethanol / water carrier. The primer composition is applied by operations selected from spraying, wiping, brushing, flow coating, and combinations thereof. The primer layer is allowed to dry or partially cure to form an interfacial coupling layer corresponding to primer layer (102, 202, 402).

[0165] A base layer composition is prepared comprising chitosan, nano silica, citric acid, optional polyacrylic acid, optional phytic acid, and an aqueous or alcohol / water carrier. The base layer composition is applied over the primer layer. The base layer is allowed to dry or partially cure to form a continuous interfacial support region corresponding to base region (103, 203, 403).

[0166] An outer layer composition is prepared comprising polydimethylsiloxane, one or more non fluorinated organosilicon surface modifying compounds, optional hydrophobic silica, optional titanium dioxide, optional natural polysaccharide resin, and an optional cohesion promoting additive. The outer layer composition is applied over the base layer. Final curing is carried out under ambient conditions or at a temperature not exceeding about 80°C. The resulting article comprises a primer assisted multilayer coating system containing a primer region (102, 202, 402), a base region (103, 203, 403), and an outer protective region (104, 204, 404).

[0167] Embodiment 2. Single Laver Multifunctional Coating on a Polymeric Substrate A polymeric substrate is selected. The polymeric substrate may be cleaned, surface activated, pretreated, or combinations thereof, where such treatment is desired for coating continuity or adhesion. A single multifunctional coating composition isprepared comprising a film forming adhesion promoting polymeric material, an inorganic particulate structuring agent, a crosslinking or network forming agent, a low surface energy surface forming material, and one or more organosilicon surface modifying compounds. The composition is deposited by operations selected from spray coating, dip coating, wiping, rolling, and combinations thereof. The deposited layer is dried, set, or cured to form one integrated coating region (302). The resulting article comprises a single layer multifunctional protective coating in which interfacial function, structural function, and surface function are integrated in one continuous coating body (302).

[0168] Embodiment 3. Low Temperature Coating of a Mixed Material Article

[0169] A mixed material article containing a metallic portion and a polymeric portion is selected. The metallic portion and the polymeric portion are cleaned individually or jointly. A primer composition selected to improve adhesion across the metallic portion and the polymeric portion is applied to one or both portions where required. A base layer composition is selected to provide adhesion, structural support, and interfacial durability. An outer layer composition is selected to provide low surface energy surface expression and protective surface function. Deposition is performed in sequence. Curing is carried out under ambient conditions or at a low elevated temperature selected to avoid unacceptable thermal distortion of the polymer containing region. The resulting coated article retains the mixed material character of the substrate while receiving a continuous protective coating architecture corresponding to primer layer (102, 202, 402), base region (103, 203, 403), and outer region (104, 204, 404).

[0170] Embodiment 4. Sustainable Biopolymeric Embodiment

[0171] A coating composition is prepared comprising a naturally derived polymeric material selected from chitosan, a cellulose derivative, a starch derivative, alginate, lignin, and combinations thereof. An inorganic particulate structuring agent is incorporated intothe polymeric phase. A crosslinking or network forming agent is incorporated into the composition. The resulting formulation is deposited as a single layer coating or as a base layer of a multilayer system. Where a multilayer system is formed, an outer layer composition containing a low surface energy constituent and an organosilicon constituent is subsequently applied. Final drying or curing yields a protective coating system containing naturally derived or bio based constituents in an amount sufficient to contribute film formation, adhesion, interfacial stabilization, or structural support.

[0172] Embodiment 5. Primer Base Outer Embodiment with Low Temperature Cure A primer composition comprising glycidoxypropyltrimethoxysilane, a silica containing inorganic particulate, an acid catalyst, and an alcohol / water carrier is applied to a substrate. The primer layer is allowed to dry or partially cure. A base layer composition comprising chitosan, nano silica, and citric acid is then applied. The base layer is allowed to develop film continuity and partial network formation. An outer layer composition comprising polydimethylsiloxane, a non fluorinated silane, and hydrophobic silica is then applied. Final curing is conducted at a temperature of about 40°C to about 80°C for a period sufficient to complete solvent removal, silane condensation, film consolidation, and network development. The resulting coated article comprises a preferred low temperature multilayer embodiment corresponding to primer layer (102, 202, 402), base region (103, 203, 403), and outer region (104, 204, 404).

[0173] Embodiment 6. Field Applied Protective Coating Embodiment

[0174] A substrate fixed in an installed environment is selected. Surface cleaning is carried out in situ. A primer composition, where required, is applied by wiping, brushing, or spraying. A base layer composition is applied by spray or wipe deposition. An outer layer composition is subsequently applied by spray or wipe deposition. Drying or curing is performed under ambient conditions or under mild heating available at theinstallation site. The resulting article comprises a field applied protective coating system suitable for retrofit service.

[0175] Embodiment 7. Heat Sensitive Flexible Substrate Embodiment

[0176] A flexible substrate or elastomeric substrate is selected. Surface preparation is performed using a non destructive cleaning step. A single layer composition or a multilayer composition having low temperature curability is selected. Deposition is performed by dip coating, spray coating, or wipe coating. Drying or curing is performed under ambient conditions or at a low elevated temperature selected to prevent unacceptable deformation of the substrate. The resulting coated article comprises a flexible coated substrate having protective surface function.

[0177] Embodiment 8. Optional Photocatalytic Outer Laver Embodiment

[0178] An outer layer composition is prepared comprising polydimethylsiloxane, a non fluorinated organosilicon constituent, hydrophobic silica, and optionally titanium dioxide. The outer layer composition is deposited over a previously formed base layer or over a substrate surface prepared for acceptance of the outer layer composition. Final curing produces an outer region (104, 204, 404) having low surface energy function, particulate surface structure, and an optional photocatalytic associated constituent. The resulting embodiment remains within the scope of the invention irrespective of whether photocatalytic function is explicitly emphasized during intended use.

[0179] The foregoing examples define representative embodiments of primer assisted systems, single layer systems, multilayer systems, low temperature systems, field applied systems, sustainable systems, mixed material systems, heat sensitive substrate systems, and optional additive systems. The foregoing examples are non limiting. Variations in constituent identity, constituent proportion, carrier system, deposition route, cure schedule, substrate class, layer thickness, and intercoat interval remain within the scopeof the invention provided the structural architecture and functional allocation described herein are retained.

[0180] Prophetic Test Methods

[0181] The following test methods define representative evaluation protocols for embodiments of the invention and establish technical criteria for the assessment of surface function, structural integrity, interfacial stability, and resistance to service exposure. Unless expressly identified elsewhere as actual experimental work, the following protocols are prophetic. They do not limit the invention to any single numerical outcome, but rather outline permissible methods of evaluating embodiments within the scope of the invention.

[0182]

[0183] Evaluation

[0184] A coated article is placed on a level support. A test liquid comprising deionized water is deposited on the exposed coating surface in a controlled droplet volume. The droplet may have a volume from about 2 to about 20 microliters, and preferably from about 3 to about 10 microliters. Surface response is evaluated by techniques selected from visual observation, static contact angle measurement, advancing contact angle measurement, receding contact angle measurement, sliding angle measurement, roll off observation, and combinations thereof. The observed response is utilized to assess the degree of wetting resistance, droplet mobility, retention behavior, and surface energy expression.

[0185] Self Cleaning Evaluation

[0186] A defined particulate load, a defined residue forming contaminant, or combinations thereof, are placed on the coated surface. Representative contaminants may be selected from mineral powder, silica dust, carbonaceous particulate, soil simulants, dried aqueous residue, food derived residue, and combinations thereof. Water is introducedto the contaminated surface under conditions selected from gravity driven motion, droplet impact, flowing rinse conditions, and combinations thereof. Removal, reduction, or displacement of the contaminant is assessed visually or by analytical techniques selected from mass comparison, image analysis, surface coverage comparison, and combinations thereof. The assessment is used to evaluate self cleaning behavior, residue release behavior, and contamination persistence.

[0187] Steam Exposure Evaluation

[0188] A coated article may be subjected to repeated steam exposure under controlled temperature, controlled exposure duration, and controlled cycling frequency. Steam exposure may be carried out at temperatures from about 80°C to about 200°C, with a preferred evaluation range from about 100°C to about 180°C. The number of exposure cycles may range from 1 to 500, with a preferred screening interval from 5 to 100 cycles. After completion of the selected exposure interval, the coating is evaluated for coating defects selected from loss of coating continuity, visible cracking, blistering, delamination, change in wetting behavior, loss of surface function, and combinations thereof. The protocol is used to assess steam exposure tolerance of the coating embodiment under the selected conditions.

[0189] Detergent and Chemical Exposure Evaluation

[0190] A coated substrate is exposed to chemicals selected from one or more detergent compositions, cleaning solutions, aqueous alkaline media, aqueous acidic media, solvent containing cleaning agents, and combinations thereof. Exposure may occur by operations selected from immersion, wipe exposure, spray exposure, standing contact, cyclic wash exposure, and combinations thereof. Exposure time may range from about 1 minute to about 168 hours, with a preferred screening interval from about 10 minutes to about 24 hours. After exposure, the coating is inspected for defects selected from visible degradation, swelling, softening, delamination, erosion, discoloration, loss ofhydrophobic response, loss of coating continuity, and combinations thereof. The protocol is used to assess the resistance of the coating embodiment to cleaning associated chemistry and chemical service exposure.

[0191] Adhesion and Durability Evaluation

[0192] A coated article is evaluated for interfacial attachment and mechanical persistence by operations selected from tape testing, rubbing, wipe cycling, abrasion simulation, scratch simulation, and combinations thereof. The selected method is matched to the substrate class, coating thickness, and intended use condition. After testing, the coating is examined for defects selected from coating removal, partial detachment, cracking, powdering, visible wear, loss of functional surface response, and combinations thereof. The protocol is used to assess adhesion retention, mechanical durability, and interfacial stability under handling or service relevant disturbance.

[0193] Thermal Exposure Evaluation

[0194] A coated article may be exposed to elevated temperature, repeated heating cooling cycling, or combinations thereof. The selected temperature may range from about 40°C to about 250°C, with a preferred evaluation range from about 60°C to about 180°C. The selected exposure time may range from about 10 minutes to about 168 hours, with a preferred screening interval from about 30 minutes to about 24 hours. After exposure, the coating is examined for defects selected from cracking, embrittlement, delamination, dimensional instability, loss of continuity, visible deformation, loss of hydrophobic response, and combinations thereof. The protocol is used to assess thermal stability of the coating embodiment under the selected thermal conditions.

[0195] Moisture and Humidity Exposure Evaluation

[0196] A coated article is exposed to conditions selected from high humidity environments, condensing humidity, repeated wet dry cycling, and combinations thereof. Relativehumidity may range from about 60% to about 100%, with a preferred screening range from about 85% to about 100%. Exposure time may range from about 1 hour to about 1000 hours. After exposure, the coating is evaluated for defects selected from whitening, swelling, softening, loss of adhesion, loss of wetting resistance, and combinations thereof. The protocol is used to assess the response of the coating embodiment to moisture dominated service conditions.

[0197] Fouling and Scaling Evaluation

[0198] A coated surface is contacted with media selected from a fouling medium, a scaling medium, and combinations thereof. Fouling media may be selected from particulate suspensions, organic residue sources, protein containing fluids, carbohydrate containing fluids, and combinations thereof. Scaling media may be selected from hard water simulants, calcium containing solutions, magnesium containing solutions, and combinations thereof. Following exposure, the surface is examined for deposit formation, deposit retention, deposit adhesion, ease of removal, or combinations thereof. The protocol is used to assess the fouling resistance and scaling resistance of the coating embodiment under the selected exposure conditions.

[0199] BEST METHOD OF PERFORMING THE INVENTION

[0200] The best method presently known to the applicant for performing the invention comprises a primer assisted multilayer coating architecture containing a primer layer (102, 202, 402), a base layer (103, 203, 403), and an outer layer (104, 204, 404). The primer layer (102, 202, 402) comprises a silane coupling and silica containing interfacial composition. A preferred primer composition comprises glycidoxypropyltrimethoxysilane in an amount from 15 to 30 wt% of primer solids, colloidal silica or nano silica in an amount from 25 to 50 wt% of primer solids, an acid catalyst in an amount from 0.1 to 3 wt% of primer solids, and optional auxiliaryadditives in an amount from 0 to 10 wt% of primer solids. A preferred liquid formulation solids content is from 5 to 15 wt%. A preferred carrier system comprises an ethanol / water mixture.

[0201] The base layer 103, 203, 403 comprises a chitosan silica acid network forming composition. A preferred base layer composition comprises chitosan as the principal film forming adhesion promoting polymeric material in an amount from 15 to 30 wt% of base layer solids, nano silica as the principal inorganic particulate structuring agent in an amount from 15 to 35 wt% of base layer solids, and citric acid as the principal crosslinking or network forming agent in an amount from 2 to 8 wt% of base layer solids. The base layer 103, 203, 403 may further comprise optional constituents selected from polyacrylic acid in an amount from 0.5 to 15 wt% when present, phytic acid in an amount from 0.5 to 10 wt% when present, GLDA in an amount from 0.1 to 10 wt% when present, benzotriazole in an amount from 0.05 to 5 wt% when present, zinc gluconate in an amount from 0.05 to 8 wt% when present, and combinations thereof. A preferred liquid formulation solids content is from 10 to 25 wt%. A preferred carrier is selected from water, acidified water, an ethanol / water mixture, and combinations thereof.

[0202] The outer layer (104, 204, 404) comprises a polydimethylsiloxane / organosilicon low surface energy composition. A preferred outer layer composition comprises polydimethylsiloxane as the principal low surface energy surface forming material in an amount from 30 to 55 wt% of outer layer solids, one or more non fluorinated organosilicon surface modifying compounds, such as methyltriethoxysilane or octyltriethoxysilane, in an amount from 2 to 10 wt% of outer layer solids, and hydrophobic silica in an amount from 5 to 18 wt% of outer layer solids. The outer layer (104, 204, 404) may further comprise optional constituents selected from titanium dioxide in an amount from 0.5 to 15 wt% when present, a natural polysaccharide resin in an amount from 1 to 20 wt% when present, citric acid in an amount from 0.5 to 8 wt% when present, and combinations thereof. A preferred liquid formulation solidscontent is from 5 to 18 wt%. A preferred carrier is selected from ethanol, isopropanol, ethyl acetate, and combinations thereof.

[0203] The preferred method of preparation proceeds by formulating each composition separately. The primer composition is prepared by charging an ethanol / water carrier to a mixing vessel, introducing glycidoxypropyltrimethoxysilane under agitation, introducing the acid catalyst, introducing the colloidal silica or nano silica, and continuing mixing until a substantially homogeneous primer formulation is obtained. The base layer composition is prepared by charging an aqueous or alcohol / water carrier to a mixing vessel, dissolving or dispersing chitosan under acidic conditions, introducing citric acid, introducing nano silica under agitation or sonication, introducing optional constituents, namely polyacrylic acid, phytic acid, GLDA, benzotriazole, and zinc gluconate, where desired, and continuing mixing until a coatable base layer formulation is obtained. The outer layer composition is prepared by charging an organic or alcohol carrier to a mixing vessel, introducing polydimethylsiloxane, introducing the organosilicon surface modifying compound, introducing hydrophobic silica, introducing optional constituents where desired, and continuing mixing or sonication until a stable outer layer formulation is obtained. This operative chemistry enables low temperature curing through natural acid based crosslinking, silane hydrolysis and condensation, and the coordinated film forming behavior of the specified constituents.

[0204] The preferred method of application proceeds as follows. A substrate (101, 201, 301, 401, 501) is selected from metal, ceramic, glass, polymeric, composite, and mixed material substrates. The substrate (101, 201, 301, 401, 501) is cleaned and dried. The primer composition is applied where primer use is required to form the primer layer (102, 202, 402, 503), and the primer layer (102, 202, 402, 503) is dried or partially cured. A preferred primer conversion interval is from about 5 minutes to about 4 hours at a temperature from about 20°C to about 50°C. The base layer composition is then applied over the primer layer (102, 202, 402, 503), or directly over the substrate (101,201, 301, 401, 501) where primer omission is acceptable, to form the base layer (103, 203, 403, 506). The base layer (103, 203, 403, 506) is dried, set, or partially cured. A preferred base layer conversion interval prior to outer layer application is from about 10 minutes to about 8 hours at a temperature from about 20°C to about 60°C. The outer layer composition is then applied over the base layer (103, 203, 403, 506) to form the outer layer (104, 204, 404, 506). Final curing is carried out at ambient temperature or at a low elevated temperature not exceeding about 80°C. A preferred final curing interval is from about 30 minutes to about 24 hours at a temperature from about 20°C to about 80°C, and more preferably from about 1 hour to about 12 hours at a temperature from about 25 °C to about 60°C.

[0205] A preferred dry film thickness for the primer layer (102, 202, 402, 503) is from 0.5 to 5 micrometers. A preferred dry film thickness for the base layer (103, 203, 403, 506) is from 5 to 40 micrometers. A preferred dry film thickness for the outer layer (104, 204, 404, 506) is from 2 to 25 micrometers. A preferred total dry film thickness for the multilayer coating system is from 10 to 60 micrometers.

[0206] The best method presently known to the applicant therefore comprises a primer assisted multilayer coating system comprising a GPTMS / silica primer forming the primer layer (102, 202, 402), a chitosan / nano silica / citric acid base layer forming the base layer 103, 203, 403, and a PDMS / non fluorinated organosilicon outer layer forming the outer layer (104, 204, 404), formed via sequential deposition and an ambient or low temperature cure not exceeding about 80°C. This embodiment is particularly suited to substrates (101, 201, 301, 401, 501) requiring hydrophobic surface behavior, self cleaning surface behavior, and protective durability under moisture exposure, detergent exposure, heat exposure, or steam associated service conditions.

Claims

I / We claim,1. A protective coated article comprising a substrate (101, 201, 301, 401) and a protective coating system disposed on at least a portion of the substrate (101, 201, 301, 401), wherein the protective coating system is configured either as (i) a single layer embodiment comprising a single coating region (302) disposed on the substrate (301) or on an optional primer layer (102, 202, 402), the single coating region (302) comprising a film forming adhesion promoting polymeric material, an inorganic particulate structuring, reinforcing, or surface texturing agent, a crosslinking, curing, or network forming agent, a low surface energy surface forming material, and one or more organosilicon surface modifying compounds, or as (ii) a multilayer embodiment comprising a base region (103, 203, 403) disposed on the substrate (101, 201, 401) or on an optional primer layer (102, 202, 402) and an outer region (104, 204, 404) disposed over the base region (103, 203, 403), wherein the base region (103, 203, 403) comprises a film forming adhesion promoting polymeric material, an inorganic particulate structuring, reinforcing, or surface texturing agent, and a crosslinking, curing, or network forming agent, and wherein the outer region (104, 204, 404) comprises a low surface energy surface forming material and one or more organosilicon surface modifying compounds.

2. A base layer composition for forming a base region (103, 203, 403) of a protective coating system on a substrate (101, 201, 301, 401), the base layer composition comprising a film forming adhesion promoting polymeric material, an inorganic particulate structuring, reinforcing, or surface texturing agent, and a crosslinking, curing, or network forming agent, wherein the base layer composition is depositable on the substrate (101, 201, 301, 401) or on an optional primer layer (102, 202, 402) to form the base region (103, 203, 403) beneath an outer region (104, 204, 404)comprising a low surface energy surface forming material and one or more organosilicon surface modifying compounds.

3. A method for forming a protective coating system on a substrate, the method comprising providing a substrate (501); optionally carrying out surface preparation (502) on the substrate (501); optionally applying a primer layer (503) to the substrate (501); depositing either (i) a coating composition to form a single coating region (302, 505), the single coating region (302, 505) comprising a film forming adhesion promoting polymeric material, an inorganic particulate structuring, reinforcing, or surface texturing agent, a crosslinking, curing, or network forming agent, a low surface energy surface forming material, and one or more organosilicon surface modifying compounds, or (ii) a base layer composition to form a base region (103, 203, 403, 506) and an outer layer composition over the base region (103, 203, 403, 506) to form an outer region (104, 204, 404, 506); and processing the deposited region or regions (507) by drying, setting, curing, or combinations thereof to form a protective coated article (508).

4. The protective coated article as claimed in claim 1, wherein the protective coating system is configured as the multilayer embodiment and further comprises the optional primer layer (102, 202, 402) disposed between the substrate (101, 201, 401) and the base region (103, 203, 403).

5. The protective coated article as claimed in claim 4, wherein the primer layer (102, 202, 402) comprises a silane coupling agent and a silica containing inorganic particulate component.

6. The protective coated article as claimed in claim 5, wherein the primer layer (102, 202, 402) further comprises an acid catalyst.

7. The protective coated article as claimed in claim 5, wherein the silane coupling agent comprises glycidoxypropyltrimethoxysilane, and wherein the silica containing inorganic particulate component comprises colloidal silica, nano silica, or combinations thereof.

8. The protective coated article as claimed in claim 1, wherein the protective coating system comprises the single layer embodiment and the film forming adhesion promoting polymeric material, the inorganic particulate structuring, reinforcing, or surface texturing agent, the crosslinking, curing, or network forming agent, the low surface energy surface forming material, and the one or more organosilicon surface modifying compounds are integrated within one continuous coating region (302).

9. The protective coated article as claimed in claim 1, wherein the substrate (101, 201, 301, 401) is selected from a metal substrate, a ceramic substrate, a glass substrate, a polymeric substrate, a composite substrate, and a mixed material substrate.

10. The protective coated article as claimed in claim 1, wherein the base region (103, 203, 403) comprises chitosan, nano silica, and citric acid.

11. The protective coated article as claimed in claim 1, wherein the outer region (104, 204, 404) comprises polydimethylsiloxane, a non fluorinated alkyltrialkoxysilane, and hydrophobic silica.

12. The protective coated article as claimed in claim 4, wherein the primer layer (102, 202, 402) comprises glycidoxypropyltrimethoxysilane and silica, the base region (103, 203, 403) comprises chitosan, nano silica, and citric acid, and the outer region (104,204, 404) comprises polydimethylsiloxane, a non fluorinated organosilicon compound, and hydrophobic silica.

13. The protective coated article as claimed in claim 1, wherein the protective coating system is substantially free of fluorinated compounds, per and polyfluoroalkyl substances, and hexamethyldisilazane.

14. The base layer composition as claimed in claim 2, wherein the film forming adhesion promoting polymeric material comprises a naturally derived biopolymer or a polysaccharide selected from chitosan, chitin, cellulose, a cellulose derivative, starch, a starch derivative, alginate, pectin, dextran, pullulan, lignin, and combinations thereof.

15. The base layer composition as claimed in claim 2, wherein the inorganic particulate structuring, reinforcing, or surface texturing agent comprises an inorganic oxide particulate material selected from silica, nano silica, colloidal silica, alumina, titania, zirconia, a silicate, a mixed oxide, and combinations thereof.

16. The base layer composition as claimed in claim 2, wherein the crosslinking, curing, or network forming agent comprises an organic acid or a polyfunctional acid selected from citric acid, phytic acid, tartaric acid, malic acid, succinic acid, polyacrylic acid, and combinations thereof.

17. The method as claimed in claim 3, wherein the processing of the deposited region or regions (507) is carried out under ambient conditions or at a temperature not exceeding about 80 °C.

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