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Title:
METHODS OF MAKING COATING LAYERS AND SUBSTRATES HAVING SAME COATING LAYERS
Document Type and Number:
WIPO Patent Application WO/2022/232817
Kind Code:
A1
Abstract:
Described herein are methods for treating a substrate including applying a coating to at least a portion of a substrate by contacting the substrate with a liquid conversion coating composition, where the crystallization of the coating is at least partially prevented or disturbed through drying in place at ambient conditions. The methods can provide a substrate having a coating comprising an amorphous morphology.

Inventors:
SPECHT SARAH ELAINE (US)
HEIGL JULIA (US)
Application Number:
PCT/US2022/071982
Publication Date:
November 03, 2022
Filing Date:
April 28, 2022
Export Citation:
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Assignee:
PPG IND OHIO INC (US)
International Classes:
C23C22/12; B05D3/00; C23C22/73; C23C22/74; C23C22/80; C23C22/82
Foreign References:
US20120204762A12012-08-16
US6368426B12002-04-09
DE2137052A11973-04-05
JP6515389B22019-05-22
US3899366A1975-08-12
US5618860A1997-04-08
US5275645A1994-01-04
Attorney, Agent or Firm:
META, Christopher T. et al. (US)
Download PDF:
Claims:
What is claimed is:

1. A method of treating a substrate comprising applying a coating to at least a portion of a substrate by contacting the substrate with a liquid conversion coating composition, wherein the crystallization of the coating is at least partially prevented or disturbed through drying in place at ambient conditions, and wherein the coating comprises an amorphous morphology.

2. The method of claim 1, wherein the coating dries in place at ambient conditions without use of forced air.

3. The method of claim 1, wherein the coating dries in place upon being exposed to forced ambient air for at least 10 seconds.

4. The method of any of claims 1 to 3, wherein after the coating is applied, the substrate is not exposed to a cleaning step and/or rinsing step.

5. The method of any one of claims 1 to 4, wherein the coating is applied by a roll application or a spray application, such as air spraying, airless spraying, electrostatic spraying, and/or thermal spraying.

6. A substrate formed by any of the preceding claims, wherein the substrate is further coated at least in part with a film-forming layer deposited from a film-forming composition, such as a film-forming composition that is powder or liquid.

7. The substrate of claim 6, wherein the liquid film-forming composition is solvent-borne, water-borne, electrodepositable, or 100 percent solids.

8. A substrate formed by any of the preceding claims, further comprising one or more additional film-forming layers deposited from film-forming compositions that are the same or different from the first film-forming composition.

9. The substrate of any of the preceding claims 6-9, wherein any of the film-forming layers comprise epoxy, acrylic, saturated or unsaturated polyester, alkyd, polyurethane, polyether, polyvinyl, polyurea, cellulose, silicon-based polymers including polysiloxanes, and/or combinations thereof.

10. An article comprising the substrate formed by any of the methods of any of the preceding claims.

11. The article of claim 10, wherein the article comprises at least a part of a vehicle, a structure, or an industrial protective structure, such as an electrical box enclosure, transformer housing, motor control enclosure, railcar container, tunnel, bridge, oil or gas industry component, such as, platforms, pipes, tanks, vessels, and their supports, marine components, automotive body parts, aerospace components, pipelines, storage tanks, wind turbine components, and general purpose steel specimen.

Description:
METHODS OF MAKING COATING LAYERS AND SUBSTRATES HAVING SAME

COATING LAYERS

[00011 This invention was made with Government support under Government Contract No. W9132T-17-C-0021. The United States Government may have certain rights in aspects of this invention.

CROSS-REFERENCE TO RELATED APPLICATIONS [0002] This application claims priority to U.S. Provisional Application No. 63/182,321, filed April 30, 2021, which is incorporated herein by reference in its entirety for all purposes.

FIELD OF THE INVENTION

10003 j The present invention relates to substrates having a conversion coating and methods of treating substrates.

BACKGROUND

(0004) Outdoor structures such as wind turbines, bridges, towers, tanks, pipes and fleet vehicles such as railcars, buses, and trucks are constantly exposed to the elements and must be designed to endure temperature extremes, wind shears, precipitation, and other environmental hazards without significant damage or the need for constant maintenance, which may be time-consuming and costly. Likewise, marine structures such as ship hulls and off-shore oil rigs and wind turbines are also exposed to seawater as well as extreme weather and other environmental conditions, making them susceptible to corrosion. Chemical storage transport or processing tanks or pipes such as fuel tanks and pipe linings are also vulnerable to corrosion and/or coating attack by aggressive chemicals being carried within. More effective treatment and coating systems are continually being sought to meet the specification demands of these industrial structures.

SUMMARY

(0005) The present description is directed to a method of treating a substrate comprising applying a coating to at least a portion of a substrate by contacting the substrate with a liquid conversion coating composition, wherein the crystallization of the coating is at least partially prevented or disturbed through drying in place at ambient conditions, and wherein the coating comprises an amorphous morphology. [0006] The present description is further directed to an article comprising a substrate formed by any of the methods described herein.

BRIEF DESCRIPTION OF DRAWINGS

|0007| FIG. 1 shows a top down SEM image (left) and corresponding elemental map images (right) of the grit blasted panels made according to Example AA.

DETAILED DESCRIPTION

(0008] Described herein is a method of treating a substrate comprising applying a coating to at least a portion of a substrate by contacting the substrate with a liquid conversion coating composition, wherein the crystallization of the coating is at least partially prevented or disturbed through drying in place at ambient conditions, and wherein the coating comprises an amorphous morphology. The description herein is further directed to substrates having coatings, such as an inorganic coating layer, and methods for treating such substrates to form such a coating where the coating dries in place at ambient conditions without the addition of heat, which may provide and/or enhance corrosion and/or chemical resistance to the substrate surface. The present description is further directed to a coating layer having at least a partially amorphous inorganic layer formed on at least a portion of the surface of a substrate wherein the coating layer dries in place at ambient conditions without the addition of heat. The crystallization of the coating can be at least partially prevented or disturbed through drying in place at ambient conditions. The coating layer according to the methods described herein often can provide good corrosion and/or chemical resistance, which in some cases may be due to the partially amorphous structure. The methods described herein can provide a substrate having at least a partially amorphous inorganic layer on at least a portion of the surface of the substrate.

|0009 j Suitable substrates for use in the methods described herein include rigid metal substrates such as ferrous metals, aluminum, aluminum alloys, copper, brass, and other metal and alloy substrates. The ferrous metal substrates used in the practice with the methods described herein may include iron, steel, and alloys thereof. Non-limiting examples of useful steel materials include hot and cold rolled steel, galvanized (zinc coated) steel, electrogalvanized steel, stainless steel, pickled steel, and combinations thereof. Combinations or composites of ferrous and non- ferrous metals can also be used. Profiled metals such as profiled steel are also suitable. By “profiled” is meant that the substrate surface has been physically modified such as by mechanically or chemically etching, abrading such as by sanding or blasting, carving, brushing, hammering, stamping, or punching, to affect the topography of the metal surface. For clarity, “profiled” as used in this context refers to substrates that have undergone some physical modification prior to being treated according to methods described herein; it will be appreciated that treatment according to methods described herein may also change the profile of the substrate.

[0010] The present description is directed to a method of treating a substrate comprising applying a coating to at least a portion of a substrate with a liquid conversion coating composition and allowing the coating to dry in place at ambient conditions without the addition of heat, i.e., temperatures above room temperature. The crystallization of the coating can be at least partially prevented or disturbed through drying in place at ambient conditions. By “ambient” is meant surrounding conditions without the addition of any external heat or other thermal energy. Often ambient temperature is called “room temperature,” ranging from 20 to 25 °C. A “liquid conversion coating” as used herein is a layer formed on the surface via a chemical process that reacted with the surface. The liquid conversion coating layer formed can be an inorganic layer.

[00111 The coating composition can dry in place with or without the use of forced air. By “forced air” herein refers to air that is circulated or distributed in a certain manner, for example, via a fan or blower. Forced air can be at ambient temperature. The method can omit any cleaning and/or rinsing step after the pretreatment coating composition is applied. Stated another way, no further active steps may be taken with respect to pretreatment layer, that is, after applying the liquid conversion coating composition, the substrate may be exposed to ambient conditions for a first period of time, such as 15 minutes, 30 minutes, 45 minutes, 60 minutes, 75 minutes, 90 minutes, 105 minutes, 120 minutes, 135 minutes, 150 minutes, 165 minutes, 180 minutes, or longer until fully or substantially dry. By “substantially dry,” it is meant that the coating is dry to the touch such that no coating is removed upon contact.

[0012 ] After the liquid conversion coating is allowed to dry in place, at least a portion of the layer has an amorphous morphology. The coating composition can dry in place with or without the use of forced air. Stated another way, the substrate may be exposed to ambient conditions such that at least a portion of the liquid conversion coating composition forms an amorphous morphology. A coating comprising an amorphous morphology can be a combination of crystalline, semi-crystalline, and/or amorphous morphologies at different portions of the coating, but at least a portion of the layer includes amorphous morphology.

|00!3| In some methods, after applying the liquid conversion coating composition the coated substrate can be exposed to forced ambient air for a period of time, such as 10 seconds, 20 seconds, 0.5 minutes, 1.0 minutes, 1.5 minutes, 2.0 minutes, 2.5 minutes, 3.0 minutes, 3.5 minutes, 4.0 minutes or longer until fully or substantially dry. The method can omit any cleaning and/or rinsing step after the pretreatment coating composition is applied. Stated another way, no further active steps other than exposing the substrate to forced ambient air, may be taken with respect to pretreatment layer, that is, after applying the liquid conversion coating composition. (0014) In the present methods, the coating can be applied by a roll application or a spray application, such as air spraying, airless spraying, electrostatic spraying, and/or thermal spraying. For spraying, the usual spray techniques and equipment for air spraying, airless spraying, electrostatic spraying, and thermal spraying and either manual or automatic methods can be used. (0015) The methods described herein can result in a treated substrate having different portions of the coated substrate surface having an amorphous morphology, for example substrates can have two different areas having different morphologies. Methods described herein can provide coated substrates having at least 10 percent amorphous morphology, such as at least 20 percent, at least 30 percent, at least 40 percent, at least 50 percent, at least 60 percent, at least 70 percent, or higher as compared to an area having a crystalline morphology. The methods can include defined areas, or areas with boundaries, having a particular morphology, or include a surface having amorphous structures interspersed within a crystalline morphology. The presence and/or extent of crystallinity may be determined by a variety of known analytical methods, including but not limited to X-ray diffraction (XRD), electron microscopy methods such as electron diffraction or backscattering, and/or spectroscopic techniques such as Raman spectroscopy.

(0016) In some cases, the chemical conversion coatings can have a coating layer thickness of, for example, 1 nanometer to 5 microns following treatment, such as 1 to 100 nanometers or 1 to 50 nanometers. It will be appreciated that the layer may have variable thickness and thus appear semicontinuous when it is in fact continuous. When a continuous or semi-continuous layer is formed on the substrate, the layer can have a thickness that is uniform or a thickness that is variable; that is, the layer will have a different thickness at different locations on the treated substrate. The thickness of the layer, sometimes referred to herein as “coating layer thickness” may range from one nanometer to five microns, and may be 1 to 100 nanometers, such as one to 50 nanometers, in some locations. Thickness can be determined using known methods, such as scanning electron microscopy (SEM) and/or transmission electron microscopy (TEM). In some cases, utilizing the methods described herein, equal or better corrosion protection can be achieved by the current substrates even though the coating layer thickness may be variable and notably thinner in at least some spots as compared to some conventional treatments. For example, in some cases, utilizing the methods described herein, a substrate having a coating layer and corresponding thickness (and relatedly a coating weight) that is less than a conventional coating layer, for example of crystalline zinc phosphate, can provide comparable corrosion protection to such a conventional coating layer due to the amorphous morphology of a coating layer prepared according to the methods described herein.

[0017] Before treating the surface of the substrate, it is common practice, though not necessary, to remove foreign matter from the substrate by cleaning and degreasing the surface. Such cleaning typically takes place after forming the substrate (stamping, welding, etc.) into an end- use shape. The surface of the substrate can be cleaned by physical or chemical means, such as mechanically abrading the surface or cleaning/degreasing with commercially available alkaline or acidic cleaning agents that are well known to those skilled in the art, such as sodium metasilicate and sodium hydroxide. A non-limiting example of a cleaning agent is CHEMKLEEN 163, an alkaline-based cleaner for metal substrates commercially available from PPG Industries, Inc.

[0018] The substrate can optionally be rinsed, such as with deionized (DI) water, and then dried, such as in an oven or other forced air dryer. Depending on the chemical conversion coating, an activator to assist with the formation of the conversion coating may be used. A rinse conditioner, such as a titanium solution, Jernstedt salt, or zinc phosphate dispersion, for example one commercially available from PPG Industries, Inc. as VERSABOND RC, may be used to rinse the substrate prior to modifying the surface with the chemical conversion coating. Other methods for applying a chemical conversion coating on a substrate can be utilized, for example electrodeposition, plasma deposition or chemical vapor deposition.

[0019] Performance data of substrates according to the description herein can be better than conventionally treated substrates. Substrates treated according to the methods described herein may exhibit increased barrier as compared to conventionally treated substrates. [0020] A substrate may have one continuous surface, or two or more surfaces such as two opposing surfaces. Typically, the substrate surface that is treated is any that can be expected to be exposed to conditions susceptible to corrosion and/or chemical damage. Examples of particular substrates include a structure, a vehicle, or industrial protective structure such as an electrical box enclosure, transformer housing, or motor control enclosure; a railcar container, tunnel, oil or gas industry component such as platforms, pipes, tanks, vessels, and their supports, marine component, automotive body part, aerospace component, pipeline, storage tank, or wind turbine component. “Structure” as used herein refers to a building, bridge, oil rig, oil platform, water tower, power line tower, support structures, wind turbines, walls, piers, docks, levees, dams, shipping containers, trailers, and any metal structure that is exposed to a corrosive environment. “Vehicle” refers to in its broadest sense all types of vehicles, such as but not limited to cars, trucks, buses, tractors, harvesters, heavy duty equipment, vans, golf carts, motorcycles, bicycles, railcars, airplanes, helicopters, boats of all sizes and the like.

{0021 ] The substrate can comprise chemical storage, transport or processing pipes and/or tanks such as a fuel tank, a railcar tank used to store and transport, for example, oils and other hydrocarbons, and pipes used to transport gas, oils and other hydrocarbons, water and other liquids. The surface of the tank and/or pipe treated with a conversion coating may be an internal surface and/or external surface of the tank or pipe. The tank or pipe may be made of steel, ferrous metals or non-ferrous metals.

[0022] The substrates treated according to methods described herein may optionally be coated with a further coating layer or multiple coating layers. For example, a film-forming layer may be applied to at least a portion of the treated substrate surface. The film-forming layer can be deposited from a film-forming composition; the film-forming composition may be curable. Suitable film-forming compositions may be a liquid, such as a solventborne or waterborne liquid, or 100 percent solids, or may be solid, particulate powders. The liquid coatings may be electrodepositable; that is, it can be applied by electrodeposition. The term “curable”, as used for example in connection with a curable composition, means that the indicated composition is polymerizable or crosslinkable through functional groups, e.g., by means that include, but are not limited to, thermal and/or catalytic exposure, or through evaporation, coalescence, oxidative crosslinking and the like. The term “cure”, “cured” or similar terms, as used in connection with a cured or curable composition, e.g., a “cured composition” of some specific description, means that at least a portion of the polymerizable and/or crosslinkable components that form the curable composition is polymerized and/or crosslinked. Additionally, curing of a polymerizable composition refers to subjecting said composition to curing conditions such as but not limited to thermal curing, leading to the reaction of the reactive functional groups of the composition. The film-forming layer may be thermoset or thermoplast. Thermoset refers to components that crosslink or “set” while thermoplast (also referred to as “thermoplastic”) refers to resins that do not become joined by covalent bonds and can undergo liquid flow upon heating and/or become soluble in solvents.

[0023] Any suitable film-forming composition can be used according to the methods described herein. As used herein, the term “film-forming composition” refers to a composition, typically comprising a film-forming resin, that can form a self-supporting continuous film on at least a horizontal surface of a substrate upon removal of any diluents or carriers present in the composition or upon curing at ambient or elevated temperature.

{0024] A film-forming layer may comprise epoxy, acrylic, saturated or unsaturated polyester, alkyd, polyurethane, polyether, polyvinyl, polyurea, cellulose, silicon-based polymers including polysiloxanes, and/or combinations thereof. For example, a film-forming layer can comprise a co-polymer of one of more of epoxy, acrylic, saturated or unsaturated polyester, alkyd, polyurethane, polyether, polyvinyl, polyurea, cellulose, and/or silicon-based polymers including polysiloxanes. In some cases, a film-forming layer can comprise a polymer blend of one of more of epoxy, acrylic, saturated or unsaturated polyester, alkyd, polyurethane, polyether, polyvinyl, polyurea, cellulose, and/or silicon-based polymers including polysiloxanes.

[0025] Film-forming resins that may be used in connection with the present methods include, without limitation, those used in automotive OEM coating compositions, automotive refmish coating compositions, industrial coating compositions, architectural coating compositions, coil coating compositions, packaging coating compositions, protective and marine coating compositions, and aerospace coating compositions, among others.

[0026] Examples of film-forming resins suitable for use in the coating compositions of the present methods include, for example, resins based on acrylic, saturated or unsaturated polyester, alkyd, polyurethane or polyether, polyvinyl, polyurea, cellulosic, silicon-based polymers including polysiloxanes, and co-polymers thereof, which resins may contain reactive groups such as epoxy, carboxylic acid, hydroxyl, isocyanate (including blocked isocyanate groups), amide, carbamate, amine and carboxylate groups, thiol groups, urea groups, among others, including mixtures thereof.

100271 Combinations of film-forming resins can be used. For example, the additional film forming resin included in the epoxy coating compositions that may be used with the present methods may comprise a resin with functionality that will cure with the amine, or alternatively, an additional crosslinker can be used. Suitable crosslinkers can be determined by those skilled in the art based on the additional resin(s) chosen.

[0028] The film-forming composition may be intumescent; i.e., it may swell or char when exposed to a flame, thus exhibiting flame retardant properties. The film-forming composition may be electrodeposited by anodic or cathodic processes and contain acrylic and/or epoxy resins. The film-forming composition may be a thermoplastic powder. The thermoplastic powder composition may contain vinyl resins such as PVC and/or PVDF and/or polyolefmic resins for example polyethylene and polypropylene. Furthermore, the thermoplastic powder composition may contain nylon based (i.e. polyamide) resin as well as polyester resins. The film-forming composition may be a thermoset powder. Thermoset powder compositions may contain epoxy and/or novolac epoxy resins with functional groups containing but not limited to carboxylic acid functionality, amine functionality, acid anhydrides, dicyandiamide, and/or phenolic functionality. Thermoset powder compositions may also contain polyester resins with hydroxyl functionality and/or carboxylic functionality. Thermoset powder compositions may also contain acrylic resins with GMA functionality, hydroxyl functionality, and/or carboxylic functionality. Thermoset powder composition may also contain silicone-based polyesters. Thermoset and thermoplastic powder compositions may be applied electrostatically and/or by thermal spray.

{0029] In some examples, the film-forming composition may comprise a polysiloxane, alone or in combination with an epoxy resin, a polyurethane, a polyepoxide, a polyester, a polyaspartic functional polymer, and/or a polyurea. Epoxy resins used in the film-forming compositions may be polyepoxides. Epoxy resins are often used in a pigmented primer and/or a pigmented coat or topcoat composition.

[0030] An example of a commercially available film-forming composition comprising a polysiloxane is PSX 700 (commercially available from PPG), an engineered siloxane coating that also contains some epoxy resin, manufactured according to United States Patent Numbers 5,618,860 and 5,275,645. Suitable film-forming compositions comprising polyurethane include SPM76569, a direct-to-metal coating composition (available from PPG); W43181A, a polyurethane primer (available from PPG); and HPP2001, a high-performance polyurethane primer (available from PPG). Suitable pigmented polyepoxide compositions include AMERLOCK 400, an epoxy primer (available from PPG); PHENGUARD 930/935/940 and NOVAGUARD 840, epoxy tank liners (available from PPG); and SEP74860, an epoxy primer (available from PPG). In some cases, such as when the film-forming composition comprises a polysiloxane and optionally a polyepoxide, the composition may be applied directly to an impregnated surface with no intervening layer. The impregnated surface refers to the pretreatment layers as formed by the methods described herein. The performance may be comparable if not better than that observed with a substrate that has been treated with an epoxy primer and the same polysiloxane top coat applied in a conventional manner.

[0031] The film-forming composition in contact with the impregnated surface typically demonstrates a pigment to binder ratio (P:B) of 0.1:1 to 35:1, such as 0.5:1 to 3.0:1. When the coated substrate comprises a storage tank lining, the film-forming composition can have a pigment volume concentration of 10 percent by volume to 50 percent by volume, such as 14 percent by volume to 40 percent by volume (based on liquid coating). The film-forming composition can be a clear coat, with less than 5 percent by volume, such as less than 2 or less than 1 percent by volume, of pigment, or no pigment at all (i.e., 0 percent by volume).

[0032) The film-forming composition applied to the treated surface may comprise a prefabrication shop coating or shop primer that is intended to provide protection during manufacturing and/or transport of an article. Examples of a prefabrication shop coating or shop primer includes epoxy, zinc-containing epoxy, inorganic zinc-based, or alkyd compositions. A shop primer or pre-fabrication primer is a temporary coating that is intended to provide protection from corrosion as a result of the elements or damages and scratches and the like. In many cases this pre-fabrication primer or shop primer is maintained as part of the final coating system. In highly demanding systems, like tank coatings for aggressive chemicals or potable water, these primers may be removed. An example of such a coating is a shop primer or holding primer, which optionally comprises a silicate. The pre-fabrication shop coating or shop primer may be left in place or may be a temporary coating that is removed prior to application of a permanent coating, i. e., a film-forming composition (b). [0033] The coated substrates of the methods and articles described herein may further comprise (c) a second film-forming layer on top of at least a portion of the film-forming layer (b). The second film-forming layer may be deposited from a composition that is pigmented or clear. As with the first film-forming composition, the second film-forming composition may be any suitable film-forming composition, such as those described above. In a particular combination, the first film-forming composition may comprise zinc and the second film-forming composition may comprise a polysiloxane and optionally an epoxy resin. Film-forming compositions that contain zinc include inorganic zinc coatings that may further comprise silicate, and zinc-rich primer coatings that further comprise an organic material such as an epoxy resin. Zinc-rich compositions typically comprise at least 40 weight percent zinc metal, such as 50 to 95 weight percent. AMERCOAT 68HS (available from PPG) is an example of a commercially available zinc-rich primer coating with a polyepoxide. Any number of coating layers can be applied to one substrate. When two or more coating layers are deposited, the layers may be the same or different. The first coating composition may be completely or partially cured before application of the second coating composition, or may be applied “wet on wet” with little or no cure or only an air dry step between applications of the two coating layers.

[0034] In other particular coating layer combinations, the first film-forming composition may comprise an epoxy resin, particularly one derived from Bisphenol A and/or Bisphenol F (or novolac) and optionally zinc, and the second film-forming composition may comprise a polyurethane; or the first film-forming composition may comprise a polyepoxide derived from Bisphenol A and/or Bisphenol F (or novolac) and optionally zinc, and the second film-forming composition may comprise a polysiloxane and a polyepoxide. A polyurethane topcoat designed for automotive refmish and available from PPG as AUE-370, is particularly suitable over a primer comprising a poly epoxide such as CRE-321 (available from PPG).

[0035] When curable compositions are used, they can be prepared as a two-package composition (but not necessary), typically curable at ambient temperature. Two-package curable compositions are typically prepared by combining the ingredients immediately before use, or can be applied by dual feed equipment as well. They can also be prepared as one-package curable compositions. [0036] The compositions may be applied to the treated substrate surface by a number of methods including spraying, electrodeposition, dipping/immersion, brushing, and/or flow coating. For spraying, the usual spray techniques and equipment for air spraying, airless spraying, electrostatic spraying, and thermal spraying and either manual or automatic methods can be used. The coating layer typically has a dry film thickness of a broad range, such as anywhere from 5 microns to 25.4 mm, depending on the particular industrial application. For example, an intumescent coating may have a dry film thickness of 500 to 1000 mils (12.7 to 25.4 mm). A pre fabrication shop coating or shop primer may have a dry film thickness of 5 to 30 microns. A tank lining system may range from 60 to 1200 microns depending on the chemistry, such as 300 to 400 microns. A dry film thickness of 1000 to 1200 microns is typical for a tank lining system comprising a poly epoxide. An electrocoat may have a dry film thickness of 10 microns to 35 microns. In general, the dry film thickness of the coating may range from 2-25 mils (50.8-635 microns), often 5-25 mils (127-635 microns).

[0037] After forming a film of the coating on the substrate, the composition can be cured if necessary by allowing it to stand at ambient temperature, or a combination of ambient temperature cure and baking; UV light cure could also be used depending on the coating chemistry. The composition can be cured at ambient temperature typically in a period ranging from 4 hours to as long as 2 weeks. If ambient humidity is below 40 percent relative humidity then cure times may be extended.

[0038] The coated substrates of the methods described herein may demonstrate corrosion resistance, enhanced adhesion, blister resistance, chemical resistance, and/or temperature resistance (i. e., resistance to damage by extreme temperatures) as compared to substrates that have not been treated as described herein. They are applicable, for example, for use on a substrate surface (such as a ship hull or offshore oil rig) that is to be in contact with water, including seawater. Additionally, the coated substrate may demonstrate resistance to aggressive chemicals as determined by chemical immersion testing in accordance with ISO 2812-1:2007 and/or ASTM D6943-15 (2015). Examples of aggressive chemicals include acids such as fatty acids, alcohols, and hydrocarbons, combinations and sequences thereof.

[0039] The coated substrates described herein may be prepared in a batch, or step-by-step process. The present methods can be further directed to a continuous process for preparing a coated substrate, further comprising applying a pre-fabrication shop coating or shop primer or other coating to the treated substrate surface as the substrate moves along a conveyor to form a coated substrate. The steps of treating the substrate and applying the film-forming composition may be adapted to an existing continuous production line for manufacturing an industrial article. Substrates made according to the present methods described herein may also be all or a portion of an existing structure or a vehicle. Repainting of such structures/vehicles typically occurs in the field and may include the removal of one or more existing coating layers prior to treatment as described herein. Such paint removal may be done by blasting the surface with an abrasive particle. According to the present description herein, a substrate can be blasted first with particles alone to remove the existing paint and/or oxide layer in a first step, and then in a second step be treated according the methods described herein, for example.

[0040] Although any conversion coating can be used with any first and optionally second coating layer, some particular combinations demonstrate particularly unexpected results with respect to corrosion inhibition, adhesion enhancement, blister resistance, and/or chemical resistance as enumerated below and as illustrated in the Examples. More specifically, such results may be observed when using a zinc phosphate conversion coating with epoxy resin coatings and optionally with urethane on top of the epoxy.

{0041 ] As used herein, unless otherwise expressly specified, all numbers such as those expressing values, ranges, amounts or percentages may be read as if prefaced by the word “about”, even if the term does not expressly appear. Any numerical range recited herein is intended to include all subranges subsumed therein. When ranges are given, any endpoints of those ranges and/or numbers within those ranges can be combined with the scope of the present invention. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements. Plural encompasses singular and vice versa. For example, while the invention has been described in terms of “a” conversion coating, “a” particle, “a” film-forming layer, “a” substrate, and the like, mixtures of these and other components, including mixtures, can be used. “Including”, “such as”, “for example” and like terms means “including/such as/for example but not limited to”. Similarly, as used herein, the terms “on”, “applied on/over”, “formed on/over”, “deposited on/over”, “overlay” and “provided on/over” mean formed, overlay, deposited, or provided on but not necessarily in contact with the surface. For example, a coating layer “formed over” a substrate does not preclude the presence of one or more other coating layers of the same or different composition located between the formed coating layer and the substrate. (0042) Each of the characteristics and examples described above and below, and combinations thereof, may be said to be encompassed by the present invention.

|0043| The invention will be further described by reference to the following example.

EXAMPLE AA

Blasting of Steel Panels using Pretreated Grit

(0044) LG25 steel grit was used to blast 3-inch x 6-inch hot rolled steel panels in a 2636 SRC-12 Pro-Finish Empire blast cabinet at an air pressure of 80 PSI to achieve a 63 ± 8 micron blast profile. These panels were sprayed with dry-in-place pretreatment as described below.

Zinc Phosphate Pretreatment of Grit Blasted Panels by Dry-in-Place Method (0045) Blasted panels were sprayed with Chemfos™ 2007HS with a Binks 61 HVLP spray gun with a 66SD tip at 35 PSI. Two passes with a 15-second flash in between. Panels were ambient dried for two hours.

(0046) Figure 1 shows a top down SEM image (left) and corresponding elemental map images (right) of the as prepared panels, i.e., the panels pre-treated according to the dry-in-place method. To generate the images, the panel segments were mounted on aluminum stubs with carbon tape and coated with Au/Pd for 20 seconds. Samples were then analyzed in a Quanta 250 FEG SEM under high vacuum. The accelerating voltage was set to 10.00 kV and the spot size was 3.0. Bulk or Point EDX was collected from the analyzed areas on each panel. The detection limit of EDX is ~1.0 wt. % within the area of analysis.

(0047) Panels prepared using the dry in place (DIP) method described above as well as controls (blast-clean only; coating system numbers 1, 3, & 5 in Table 1) were coated with several solvent- borne coating systems, cured, scribed with a 2-mm wide horizontal scribe and subjected to ISO 12944-9 cyclic exposure testing and ISO 9227 neutral salt spray exposure. After exposure, the average rust creep outward from the scribe was measured and reported in the Table 1 below.

Table 1

ILLUSTRATIVE EMBODIMENTS

[0048] As used below, any reference to methods, articles, or substrates is understood as a reference to each of those methods, articles, or substrates disjunctively (e.g., “Illustrative embodiment 1-4 is understood as illustrative embodiment 1, 2, 3, or 4.”).

(0049] Illustrative embodiment l is a method of treating a substrate comprising applying a coating to at least a portion of a substrate by contacting the substrate with a liquid conversion coating composition, wherein the crystallization of the coating is at least partially prevented or disturbed through drying in place at ambient conditions, and wherein the coating comprises an amorphous morphology.

(0050] Illustrative embodiment 2 is a method of any preceding or subsequent illustrative embodiments, wherein the coating dries in place at ambient conditions until at least substantially dry.

[0051] Illustrative embodiment 3 is a method of any preceding or subsequent illustrative embodiment, wherein the coating dries in place at ambient conditions for a first period of time, such as at least 15 minutes, 30 minutes, 45 minutes, 60 minutes, 75 minutes, 90 minutes, 105 minutes, 120 minutes, 135 minutes, 150 minutes, 165 minutes, and/or 180 minutes.

|0052 | Illustrative embodiment 4 is a method of any preceding or subsequent illustrative embodiment, wherein the coating dries in place at ambient conditions without use of forced air. (0053] Illustrative embodiment 5 is a method of any preceding or subsequent illustrative embodiment, wherein the coating dries in place upon being exposed to forced ambient air for at least 10 seconds.

[0054] Illustrative embodiment 6 is a method of any preceding or subsequent illustrative embodiment, wherein after the coating is applied, the substrate is not exposed to a cleaning step and/or rinsing step. [0055] Illustrative embodiment 7 is a method of any preceding or subsequent illustrative embodiment, wherein the coating is applied by a roll application or a spray application, such as air spraying, airless spraying, electrostatic spraying, and/or thermal spraying.

[0056] Illustrative embodiment 8 is a substrate formed by any of the methods of the preceding or subsequent illustrative embodiment, wherein the substrate is further coated at least in part with a film-forming layer deposited from a film-forming composition, such as a film-forming composition that is powder or liquid.

[0057] Illustrative embodiment 9 is a substrate formed by any of the methods of the preceding or subsequent illustrative embodiment, wherein the liquid film-forming composition is solvent- borne, water-borne, electrodepositable, or 100 percent solids.

[0058] Illustrative embodiment 10 is a substrate formed by any of the methods of the preceding or subsequent illustrative embodiment, further comprising further comprising one or more additional film-forming layers deposited from film-forming compositions that are the same or different from the first film-forming composition.

[0059] Illustrative embodiment 11 is a substrate formed by any of the methods of the preceding or subsequent illustrative embodiment, wherein any of the film-forming layers comprise epoxy, acrylic, saturated or unsaturated polyester, alkyd, polyurethane, polyether, polyvinyl, polyurea, cellulose, silicon-based polymers including polysiloxanes, and/or combinations thereof.

[0060] Illustrative embodiment 12 is an article comprising the substrate formed by any of the methods of any preceding or subsequent illustrative embodiment.

[0061] Illustrative embodiment 13 is the article of any preceding illustrative embodiment, wherein the article comprises at least a part of a vehicle, a structure, or an industrial protective structure, such as an electrical box enclosure, transformer housing, motor control enclosure, railcar container, tunnel, bridge, oil or gas industry component, such as, platforms, pipes, tanks, vessels, and their supports, marine components, automotive body parts, aerospace components, pipelines, storage tanks, wind turbine components, and general purpose steel specimen.

[0062] Whereas particular examples of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.




 
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