CN116940614A

CN116940614A - Aqueous acid-epoxy resin coating composition

Info

Publication number: CN116940614A
Application number: CN202180092567.4A
Authority: CN
Inventors: 曹斌; Q·郑; M·A·马约; M·S·卢昌斯基; T·米兹哈拉; M·R·斯蒂巴德
Original assignee: PPG Industries Ohio Inc
Current assignee: PPG Industries Ohio Inc
Priority date: 2020-12-29
Filing date: 2021-12-29
Publication date: 2023-10-24

Abstract

A two-component aqueous coating system comprising: a first component comprising an acid functional polymer dispersed in an aqueous medium, the acid functional polymer having an acid number of at least 100 based on total resin solids; and a second component separate from the first component. The second component includes an epoxy functional compound. Also described herein is a method of preparing a two-component aqueous coating system and a two-component aqueous coating system kit.

Description

Aqueous acid-epoxy resin coating composition

Technical Field

The invention relates to a bi-component water-based coating system and a preparation method thereof.

Background

In industrial coating processes, such as those used in the manufacture of vehicles (e.g., motor vehicles), there is a continual effort to reduce atmospheric pollution caused by Volatile Organic Compounds (VOCs) emitted during the painting process. However, at low VOC levels, such as by using high solids solvent-based coatings and/or powder coatings, it is often difficult to achieve a high quality, smooth coating finish with adequate physical properties.

Disclosure of Invention

The present invention relates to a two-component aqueous coating system comprising: a first component comprising an acid functional polymer dispersed in an aqueous medium, the acid functional polymer having an acid number of at least 100 based on total resin solids; and a second component separate from the first component. The second component includes an epoxy functional compound.

The invention also relates to a method of preparing a two-component aqueous coating system, the method comprising: preparing a first component comprising an acid functional polymer dispersed in an aqueous medium, the acid functional polymer having an acid number of at least 100 based on total resin solids; filling the first container with a first component; preparing a second component comprising an epoxy functional compound; and filling a second container different from the first container with a second component.

The invention also relates to a kit of a two-component aqueous coating system, comprising: a first vessel comprising a first component comprising an acid functional polymer dispersed in an aqueous medium, the acid functional polymer having an acid number of at least 100 based on total resin solids; and a second container separate from the first container, wherein the second container comprises a second component comprising an epoxy-functional compound.

Drawings

FIG. 1 illustrates a coating system including a first component and a separate second component; and

fig. 2 shows a mixing vessel comprising a coating composition formed by contacting a quantity of a first component and a second component.

Detailed Description

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

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

Furthermore, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all subranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

In the present application, the use of the singular includes the plural and the plural encompasses singular unless explicitly stated otherwise. Furthermore, in the present application, even though "and/or" may be explicitly used in certain instances, the use of "or" means "and/or" unless explicitly stated otherwise. Furthermore, in the present application, the use of "a" or "an" means "at least one" unless explicitly stated otherwise. For example, "a" crosslinker, "an" epoxy resin, etc., refers to one or more of any of these items.

As used herein, "film-forming resin" refers to a self-supporting continuous film on at least a horizontal surface of a substrate upon removal of any diluent or carrier present in the composition or upon curing. Furthermore, as used herein, the term "polymer" refers to prepolymers, oligomers, and homopolymers and copolymers. The term "resin" is used interchangeably with "polymer".

As used herein, the transitional term "comprising" (and other comparable terms such as "contain" and "include") is "open" and open to include unspecified material. Although described as "comprising," it is within the scope of the application that the terms "consisting essentially of … …" and "consisting of … ….

The present invention relates to a two-component aqueous coating system comprising a first component and a second component. The first component includes an acid functional polymer dispersed in an aqueous medium, the acid functional polymer having an acid number of at least 100 based on total resin solids. The second component includes an epoxy functional compound and is separate from the first component.

The first component includes an acid functional polymer dispersed in an aqueous medium.

As used herein, "aqueous medium" refers to a liquid medium comprising at least 50% by weight of water, based on the total weight of the liquid medium. Such aqueous liquid medium may, for example, comprise at least 60 wt% water, or at least 70 wt% water, or at least 80 wt% water, or at least 90 wt% water, or at least 95 wt% water, or 100 wt% water, based on the total weight of the liquid medium. Solvents that make up less than 50% by weight of the liquid medium, if present, include organic solvents. Non-limiting examples of suitable organic solvents include polar organic solvents, such as protic organic solvents, e.g., glycols, glycol ether alcohols, volatile ketones, glycol diethers, esters, and diesters. Other non-limiting examples of organic solvents include aromatic hydrocarbons and aliphatic hydrocarbons. "aqueous coating composition" refers to a coating composition comprising an aqueous medium.

The acid functional polymer has an acid number of at least 100, such as at least 130, at least 140, or at least 170, based on total resin solids. Acid numbers as referred to herein were measured according to ASTM D1639 using a switzerland vanton (Metrohm) 798MPT Titrino auto-titrator.

The acid functional polymer may comprise an acrylic polymer. The acrylic polymer may comprise an addition polymer formed from ethylenically unsaturated monomers, and suitable ethylenically unsaturated groups include, but are not limited to, (meth) acrylate groups, vinyl groups, or combinations thereof. As used herein, the term "(meth) acrylate" refers to both methacrylate and acrylate. Suitable unsaturated monomers containing acid groups that can be used to form the acid functional polymer include, but are not limited to, (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, anhydrides thereof, or combinations thereof. The acid functional acrylic polymer may be formed from hydroxyl containing acrylic monomers, acrylic monomers other than hydroxyl containing acrylic monomers, and anhydrides. The acid functional acrylic polymer may be formed by reacting acrylic monomers and then post-reacting the product with an anhydride to form the acid functional acrylic polymer. The acid functional acrylic polymer may be formed by mixing acrylic monomers with an anhydride to polymerize together and ring-open to form the acid functional acrylic polymer. The acid functional acrylic polymer may be formed by pre-reacting an acrylic monomer containing a hydroxyl group with an anhydride to form a pre-monomer half-acid ester (e.g., hydroxyethyl acrylate may be reacted with hexahydrophthalic anhydride under mild reaction conditions to produce a half-acid ester that will contain one c=c group and one COOH group). Then, by reacting the pre-monomer with an acrylic monomer other than the hydroxyl-containing acrylic monomer to form an acid-functional acrylic polymer, this may form the acid-functional acrylic polymer via additional polymerization using c=c groups.

The acid functional polymer may have a weight average molecular weight (Mw) of at least 2,000, such as at least 2,500, at least 3,000, or at least 3,500. The acid functional polymer may have a Mw of up to 20,000, such as up to 15,000, up to 10,000, or up to 5,000. The acid functional polymer may have a Mw of from 2,000 to 20,000, such as from 2,000 to 15,000, from 2,000 to 10,000, from 2,000 to 5,000, from 3,500 to 20,000, from 3,500 to 15,000, from 3,500 to 10,000, or from 3,500 to 6,500.

Mw and number average molecular weight (Mn) as reported herein are measured by gel permeation chromatography using a Waters 2695 separation module with a Waters 2414 differential refractometer (RI detector) using polystyrene standards according to ASTM D6579-11; tetrahydrofuran (THF) was used as the eluent at a flow rate of 1 ml/min and separated using PLgel Mixed-C (300X 7.5 mm) column at room temperature; the weight average molecular weight and number average molecular weight of the polymer sample can be measured by gel permeation chromatography relative to a linear polystyrene standard of 800 to 900,000 da.

The acid functional polymer may have a Tg of from-40 ℃ to 80 ℃, such as from 20 ℃ to 80 ℃, from 20 ℃ to 60 ℃, or from 25 ℃ to 50 ℃. Unless otherwise indicated, tg reported herein is calculated according to Fox equation.

The two-component coating system may comprise from 20 to 90 wt%, such as from 25 to 80 wt%, from 20 to 75 wt%, or from 23 to 72 wt% of the acid functional polymer, based on the total resin solids of the coating system. The two-component coating system can comprise at least 20 wt%, such as at least 25 wt%, at least 30 wt%, at least 40 wt%, or at least 50 wt% of the acid functional polymer, based on the total resin solids of the coating system. The two-component coating system may comprise up to 90 wt%, such as up to 85 wt%, up to 80 wt%, up to 75 wt%, or up to 70 wt% of the acid functional polymer, based on the total resin solids of the coating system.

The acid-functional polymer and/or the first component can be prepared in a Continuous Stirred Tank Reactor (CSTR) to allow the acid-functional polymer to be formed at higher solids, to minimize the amount of solvent (e.g., lower VOC) required during synthesis, and/or to simplify the synthesis procedure (e.g., eliminate solvent stripping steps). The acid functional polymer and/or the first component may be prepared in a batch reactor.

The acid functional polymer as the first component may be prepared as an acrylic polymer using a CSTR. The acrylic polymer may be formed from an acrylic monomer containing a hydroxyl group, an acrylic monomer different from the acrylic monomer containing a hydroxyl group, and an acid anhydride. The acrylic polymer may be formed by reacting acrylic monomers in a CSTR and then post-reacting the product with an anhydride to form an acid functional acrylic polymer. The acrylic polymer may be formed by mixing and co-feeding acrylic monomers with an anhydride into a CSTR so as to polymerize and ring-open together in the CSTR to form an acid functional acrylic polymer. Acrylic polymers may be formed by pre-reacting hydroxyl-containing acrylic monomers with an anhydride to form a pre-monomer half-acid ester (e.g., hydroxyethyl acrylate may be reacted with hexahydrophthalic anhydride under mild reaction conditions to produce a half-acid ester that will contain one c=c group and one COOH group). Then, by reacting the pre-monomer with an acrylic monomer other than the hydroxyl containing acrylic monomer in a CSTR to form an acid functional acrylic polymer, this can form the acid functional acrylic polymer via additional polymerization using c=c groups.

The first component may be substantially free of the epoxy-functional compound described in connection with the second component (less than 5 weight percent of the epoxy-functional compound based on the total weight of components in the first component). The first component may be substantially free of epoxy functional compounds (less than 1 wt% epoxy functional compounds based on the total weight of components in the first component). The first component may be free of epoxy functional compounds (0 wt% epoxy functional compounds based on the total weight of components in the first component).

The second component includes an epoxy functional compound.

The Mw of the epoxy-functional compound may be up to 2,000, such as up to 1,500, up to 1,000, up to 750, up to 500, or up to 400. The Mw of the epoxy functional compound may be from 180 to 2,000, such as from 180 to 1,000, from 180 to 750, from 180 to 500, from 180 to 400, or from 200 to 350.

The epoxy-functional compound may include cycloaliphatic epoxy resins, aliphatic epoxy resins, hexahydrophthalic anhydride diester epoxy resins, cyclohexanedimethanol epoxy resins, neopentyl glycol based epoxy resins, polyglycidyl ether epoxy resins (e.g., 1, 4-butanediol diglycidyl ether), aromatic multifunctional epoxy resins, bisphenol a diepoxide, hydrogenated bisphenol a diepoxide, triglycidyl ethers of trimethylolpropane, novolac epoxy resins, or some combination thereof. The epoxy resin functional compound may comprise at least two epoxy resin groups, such as at least three epoxy resin groups.

The two-component coating system may comprise from 8 to 70 wt% of the epoxy-functional compound, such as from 10 to 70 wt%, from 10 to 60 wt%, from 8 to 60 wt%, from 15 to 50 wt%, or from 20 to 40 wt%, based on the total resin solids of the coating system. The two-component coating system may comprise at least 8 wt%, such as at least 10 wt%, at least 15 wt%, or at least 20 wt% of the epoxy-functional compound, based on the total resin solids of the coating system. The two-component coating system may comprise up to 70 wt%, such as up to 65 wt%, up to 60 wt%, or up to 55 wt% of the epoxy-functional compound, based on total resin solids of the coating system.

The second component may additionally comprise a second epoxy-functional compound different from the epoxy-functional compound listed above (having a different chemical structure and/or prepared from different monomers and/or amounts of monomers). The second epoxy-functional compound may be included in the second component in a lower amount than the epoxy-functional compounds listed above. The two-component coating system may comprise up to 50 wt% of the second epoxy-functional compound, such as up to 40 wt%, up to 30 wt%, up to 20 wt%, up to 10 wt%, or up to 5 wt%, based on total resin solids of the epoxy resins in the coating system. The second epoxy functional compound may comprise an epoxy functional acrylic, such as a glycidyl methacrylate based epoxy. The second epoxy functional compound may comprise a castor oil-based epoxy. The second epoxy functional compound may comprise a polyurethane-based epoxy resin, such as a polyurethane epoxy resin dispersion. In alternative examples, the coating system may be substantially free (less than 3 wt% based on total resin solids of the coating system), substantially free (less than 1 wt% based on total resin solids of the coating system), or free (0 wt% based on total resin solids of the coating system) of the second epoxy functional compound.

The second component may be substantially free of water (less than 5 wt% water based on the total weight of components in the second component). The second component may be substantially free of water (less than 1 wt% water based on the total weight of components in the second component). The second component may be free of water (0 wt% water based on the total weight of components in the second component).

The second component may be substantially free of the acid-functional polymer described in connection with the first component (less than 5 wt.% acid-functional polymer based on the total weight of components in the second component). The second component may be substantially free of acid functional polymer (less than 1 wt% acid functional polymer based on the total weight of components in the second component). The second component may be free of acid functional polymer (0 wt% acid functional polymer based on the total weight of components in the second component).

The second component is separate from the first component as shown in fig. 1. Referring to fig. 1, a coating system 10 is shown that includes a first component 12 and a second component 14. The first component 12 and the second component 14 may be stored in separate containers (also referred to herein as "packages") prior to mixing, such as until a user is ready to apply the coating composition formed by the coating system 10 to a substrate. As such, the first component 12 and the second component 14 may not contact each other until the user is ready to apply the coating composition formed by the coating system 10. Furthermore, fig. 1 shows a kit 16 comprising the coating system 10, wherein the kit comprises the first component 12 in a first container and the second component 14 in a separate second container. The second container may be substantially free of water. The second component 14 may not be in contact with the first component 12 in the kit 16.

Referring to fig. 2, a mixing vessel 18 is shown that includes a coating composition 20. The coating composition 20 is formed by contacting a quantity of the first component 12 and the second component 14, such as by combining at least a portion of the contents of separate first and second containers into the mixing container 18. The first component 12 and the second component 14 may be combined in a predetermined ratio or predetermined stoichiometric ratio of reactive functional groups on the components of the first component 12 and the second component 14 to form the coating composition 20. The ratio of acid groups to epoxy groups in the coating system (e.g., from the acid functional polymer and the epoxy functional compound, respectively) may range from 1.5:1 to 1:1.5, such as from 1.2:1 to 0.9:1 or from 1.1:1 to 1:1.1. The ratio of acid groups to epoxy groups in the coating system may be greater than or equal to 1:1. The coating system may include acid groups in excess of the epoxy groups. The mixer 22 may mix the added first component 12 and second component 14, which form the coating composition 20 to form a homogeneous mixture thereof.

With continued reference to fig. 2, the mixer 22 may include an in-line mixing device, such as an in-line two-component mixing device. By such means, each component can be pumped from its respective container through tubing or piping to the point where they are mixed together in the in-line mixing device and subsequently delivered to a coating composition applicator (not shown), such as a spray gun, bell atomizer, or the like.

With continued reference to fig. 2, upon contacting the first component 12 and the second component 14 to form the coating composition 20, the coating composition 20 may be applied to a substrate as described below. The coating composition 20 can begin to cure and/or harden upon mixing the first and second components 12, 14. The coating composition 20 can be cured to a coating at ambient temperature (20 ℃ to 27 ℃, e.g., 23 ℃) within 48 hours, such as within 24 hours, within 12 hours, or within 8 hours, of first contacting the first component 12 with the second component 14. The viscosity of the coating composition 20 can be doubled within 48 hours, such as within 24 hours, within 12 hours, or within 8 hours, of first contacting the first component 12 with the second component 14 at ambient temperature. The viscosity is determined herein using a Brookfield CAP 2000 viscometer using a #4 spindle at 300rpm at 23 ℃. When the viscosity increases above a certain threshold, its suitability for application, such as by spraying, brushing, rolling, etc., may decrease. The coating composition 20 may no longer be suitable (e.g., sprayable, brush-able, roll-coatable, etc.) within 48 hours, such as within 24 hours, within 12 hours, or within 8 hours of first contacting the first component 12 with the second component 14.

The coating system may comprise additional materials (in addition to the acid functional polymer and the epoxy functional compound) as described below, such as neutralizing amines, catalysts, crosslinkers, additional resins, pigments, and other such suitable materials and combinations of materials. Additional materials may be included in first component 12 and/or second component 14. The coating system may include additional components in addition to the first component 12 and the second component 14, such as a third component (not shown), a fourth component (not shown), and so forth. The additional component may contain at least a portion of the additional material.

The coating system can further include a neutralizing amine to at least partially neutralize the acid functional polymer to form a salt. Suitable neutralizing amines include ammonium hydroxide, dimethylamine, trimethylamine, triethylamine, monoethanolamine, diisopropanolamine, diethanolamine, dimethylethanolamine, or combinations thereof.

The neutralizing amine may be included in the first component. The neutralizing amine may be included in the second component. The neutralizing amine may be included in the first component and the second component, and the first component and the second component may include the same or different neutralizing amines.

The acid functional polymer may be neutralized at least 15%, such as at least 20%, at least 25%, or at least 30% neutralized using a neutralizing amine. The acid functional polymer may be neutralized up to 120%, such as up to 100%, up to 80%, up to 60%, or up to 50% neutralized using a neutralizing amine. The acid functional polymer may be neutralized from 15% to 120%, such as from 15% to 100%, 15% to 80%, 15% to 60%, 15% to 50%, 15% to 45%, 15% to 40%, or 15% to 35% neutralized using a neutralizing amine. Neutralization (percent total neutralization) of the acid-functional polymer can be theoretically determined based on the amine equivalent (of the neutralizing amine) divided by the acid equivalent (of the acid-functional polymer). Neutralization of the acid functional polymer within this range can result in a balance of sufficiently stable polymers included in the clear coating composition (increased neutralization results in a more stable resin) while maintaining a viscosity low enough to be used as a flowable coating composition that can be applied to a substrate, such as by spraying or other application methods described below (increased neutralization results in a more viscous resin).

The coating system may further comprise a catalyst. The catalyst may also be used as a neutralizing amine. Alternatively, the catalyst may be different from the neutralizing amine. The catalyst may be included in the first component. The catalyst may be included in the second component. The catalyst may be included in the first component and the second component, and the first component and the second component may include the same or different catalysts.

The catalyst can accelerate the curing of the epoxy resin groups and the acid groups. Examples of suitable catalysts include organic amines and quaternary ammonium compounds such as pyridine, piperidine, dimethylaniline, diethylenetriamine, 1, 4-diazabicyclo [2.2.2] octane (DABCO), tetramethyl ammonium chloride, tetramethyl ammonium acetate and tetramethyl benzyl ammonium acetate. The amount of catalyst may range from 0 to 10 wt%, such as 0.5 to 5 wt% or 0.5 to 3 wt%, based on the total resin solids of the coating system. The organic amine may comprise a tertiary amine.

The coating system may further include a crosslinker. The cross-linking agent may be included in the first component. The crosslinking agent may be included in the second component. The crosslinking agent may be included in the first component and the second component, and the first component and the second component may include the same or different crosslinking agents.

The crosslinker may comprise an aminoplast (e.g., melamine), a blocked isocyanate, a silane, an oxazoline, a carbodiimide, or some combination thereof.

The aminoplast crosslinker may comprise melamine. Aminoplast crosslinkers can include condensates of amines and/or amides with aldehydes. The aminoplast crosslinking agent may be reactive with secondary hydroxyl groups formed from the reaction of epoxy groups and carboxylic acid groups in the coating composition or hydroxyl groups that may be present on the acid functional polymer or the epoxy functional compound to crosslink the system. Aminoplast crosslinkers can also self-condense to self-crosslink. The aminoplast crosslinker may be a component of the first component, the second component, or both the first component and the second component. Non-limiting examples of aminoplast crosslinkers include RESIMENE 717, RESIMENE 718 and RESIMENE HM 2608 (both available from the reference Resins company of Erkner, germany)) or CYMEL 200 and CYMEL 1158 (both available from the Zhanxin company (Allnex) of alpha lita, georgia).

The blocked isocyanate crosslinker may be reactive with secondary hydroxyl groups formed from the reaction of epoxy groups and carboxylic acid groups in the coating composition or hydroxyl groups that may be present on the acid functional polymer or epoxy functional compound to crosslink the system. The blocked isocyanate crosslinker may be a component of the first component, the second component, or both the first component and the second component. Non-limiting examples of blocked isocyanate crosslinkers that may be included as a component of the first component include VESTANAT EP-DS1205E (trimer of isophorone diisocyanate (IPDI) blocked with methyl ketoxime, available as a water/solvent mixture from Yingchan Industrial Co., ltd (Evonik Industries) of Essen, germany) and BAYHYTHERM 3246/1 (hexamethylene diisocyanate (HDI) base and blocked with dimethylpyrazole, available as a water/solvent mixture from Koven Co., covestro of Leverkusen, germany). Non-limiting examples of blocked isocyanate crosslinkers that may be included as a component of the second component include VESTANAT B1042E (a trimer of IPDI blocked with diethyl malonate, commercially available from Yingchang industries, eisen, germany). Non-limiting examples of blocked isocyanate crosslinkers that may be included as components of the first and/or second components include DESMODUR BL3175 (HDI groups and blocked with methyl ketoxime, provided in solvent form) or DESMODUR PL350 (HDI groups and blocked with dimethylpyrazole, provided in solvent form) (both available from the Cork corporation of Lewkusen, germany) and VESTANAT B135BA (IPDI trimer and blocked with methyl ketoxime, provided in solvent form) or VESTANAT B1186A (IPDI trimer and blocked with E-caprolactam, provided in solvent form) (both available from the winning industries of Etssen, germany).

The silane crosslinking agent may self-condense to form self-crosslinks around other binder resins. The silane crosslinking agent may react with hydroxyl groups formed by the reaction of epoxy groups and carboxylic acid groups in the coating composition or hydroxyl groups that may be present on the acid functional polymer or epoxy functional compound to crosslink the system. The silane crosslinking agent may be a component of the first component, and non-limiting examples of silane crosslinking agents that may be a component of the first component include SILQUEST A-189 (gamma-mercaptopropyl trimethoxysilane) and SILQUEST A-1170 (bis-gamma-trimethoxysilylpropylamine) (both available from Michaelis advanced materials Inc. (Momentive Performance Materials) of Waterford, N.Y.). The silane crosslinker may be a component of the second component, and non-limiting examples of silane crosslinkers that may be a component of the second component include SILQUEST A-186 ((3, 4-epoxycyclohexyl) ethyltrimethoxysilane), SILQUEST A-187 (gamma-glycidoxypropyl trimethoxysilane) and COATOSIL MP-200 (epoxy functional silane oligomer) (all available from Michaelsholty, voltd, N.Y.).

The oxazoline crosslinker may be reactive with carboxylic acid groups to crosslink the system. The oxazoline crosslinker may comprise an aqueous dispersion. The oxazoline crosslinker may be a component of the first component. Non-limiting examples of oxazoline crosslinkers, which may be a component of the first component, include eporos K-2010e, K-2020e, K-2030e, WS-300, WS-500, and WS-700 (all available from Japan corporation of Tokyo (Tokyo, japan) japanese catalyst (Nippon Shokubai Co, ltd.).

The carbodiimide crosslinking agent can be reactive with carboxylic acid groups to crosslink the system. The carbodiimide crosslinking agent may contain no solvent or water, and is included as a component of the second component. Non-limiting examples of such carbodiimide crosslinking agents that may be components of the second component include PICASSIAN XL-725, XL-755, and XL-762 (Stahl, style, inc. all available from Waalwijk, netherlands).

The coating system may include additional resins other than the acid functional polymers and epoxy functional compounds described previously. Additional resins may be included in the first component. Additional resins may be included in the second component. The additional resin may be included in the first component and the second component, and the first component and the second component may include the same or different additional resins.

The additional resin may include a film-forming resin. The additional resin may include any of a variety of thermoplastic and/or thermosetting film forming resins known in the art. The term "thermoset" refers to a resin that "cures" when cured or crosslinked, wherein the polymer chains of the resin are linked together by covalent bonds. Once cured or crosslinked, the thermosetting resin does not melt and is insoluble in solvents when heat is applied. As noted above, the film-forming resin may also include a thermoplastic film-forming resin. The term "thermoplastic" refers to resins that are not covalently linked, and thus can undergo liquid flow and are soluble in certain solvents when heated.

Suitable additional resins include polyurethanes, polyesters (e.g., polyester polyols), polyamides, polyethers, polysiloxanes, fluoropolymers, polysulfides, polythioethers, polyureas, (meth) acrylic resins (other than those previously described), epoxy resins (other than those previously described), vinyl resins, copolymers thereof, and mixtures thereof. The additional resin may include a grind resin for introducing pigment into the coating system.

The additional resin may have any of a variety of reactive functional groups including, but not limited to, carboxylic acid groups, amine groups, epoxide groups, hydroxyl groups, thiol groups, urethane groups, amide groups, urea groups, isocyanate groups (including blocked isocyanate groups), (meth) acrylate groups, and combinations thereof. Blocked isocyanate and/or melamine resins may be added to the coating system as additional resins to increase the crosslink density of the coating system. The thermosetting coating composition generally comprises a crosslinking agent, which may be selected from any of the crosslinking agents known in the art to react with the functional groups of the resins used in the coating system. Alternatively, a thermosetting film-forming resin having a functional group reactive with itself may be used; in this way, such thermosetting resins are self-crosslinking.

The coating composition can include from 0 to 20 wt%, such as from 2.5 to 20 wt%, from 2.5 to 15 wt%, from 2.5 to 10 wt%, from 5 to 20 wt%, from 5 to 15 wt%, from 5 to 10 wt%, from 10 to 20 wt%, or from 15 to 20 wt% of additional resin based on the total resin solids of the coating system. The coating composition may include at least 2.5 wt.% or at least 5 wt.% or at least 10 wt.% of additional resin (if included), based on the total resin solids of the coating system. The coating composition may include up to 20 wt.% or up to 15 wt.% of additional resin (if included), based on the total resin solids of the coating system.

The coating system may also include additional materials, such as pigments. Pigments may be included in the first component. Pigments may be included in the second component. The pigment may be included in the first component and the second component, and the first component and the second component may include the same or different pigments.

Pigments may include finely divided solid powders that are insoluble but wettable under the conditions of use. The pigment may have an average particle size of at most 50 microns, such as at most 25 microns, at most 10 microns, at most 5 microns, or at most 2 microns. The average particle size can be determined by known light scattering techniques. For example, the average particle size of such particles may be measured using a Malvern Zetasizer. Pigments may be organic or inorganic and may be agglomerated or non-agglomerated. Pigments can be incorporated into the coating system by using a grind vehicle, such as an acrylic grind vehicle, the use of which is familiar to those skilled in the art. Acid functional polymers and/or epoxy functional compounds may be used as grind carriers.

Suitable pigments and/or pigment compositions include, but are not limited to, carbazole dioxazine crude pigments, azo, monoazo, diazo, naphthol AS, salt (flake), benzimidazolone, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, violacycloone, diketopyrrolopyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone, anthracenyl ketone, dioxazine, triaryl n-carbon, quinophthalone pigments, diketopyrrolopyrrole red ("DPPBO red"), titanium dioxide, carbon black, and mixtures thereof.

Pigments used with the coating system may also include special effect pigments. As used herein, "special effect pigment" refers to a pigment that interacts with visible light to provide an appearance effect other than or in addition to continuous constant color. Suitable special effect pigments include those that produce one or more appearance effects such as reflection, pearlescence, metallic luster, texture, phosphorescence, fluorescence, photochromism, photosensitivity, thermochromatism, flop and/or discoloration, such as transparent coated mica and/or synthetic mica, coated silica, coated alumina, aluminum flake, transparent liquid crystal pigment, liquid crystal coating, or combinations thereof.

The coating system can form a clear coat layer comprising up to 15 wt%, such as up to 12 wt%, up to 10 wt%, or up to 5 wt% pigment, based on the total solids of the coating system. The coating system may comprise from 0 to 15 wt%, such as from 2 to 10 wt% or from 1 to 10 wt% pigment, based on the total solids of the coating system. In some examples, the coating system can form a substantially pigment-free clear coating. By substantially pigment-free, it can be meant that the coating system comprises less than 3 wt%, such as less than 2 wt%, less than 1 wt%, or 0 wt% pigment, based on the total solids of the coating system.

Other suitable materials that may be used with the coating system include, but are not limited to, plasticizers, abrasion resistant particles, antioxidants, hindered amine light stabilizers, UV light absorbers and stabilizers, surfactants, flow and surface control agents, thixotropic agents, reaction inhibitors, and other conventional adjuvants. These materials may be included in the first component. These materials may be included in the second component. These materials may be included in the first component and the second component, and the first component and the second component may include the same or different these materials. For example, the first component may contain a first subset of additional materials and the second component may contain a second subset of additional materials, wherein the first subset and/or the second subset comprise at least one different additional material.

The coating system can be substantially free (less than 5 wt% based on total solids of the coating system) of unreacted isocyanate (e.g., at ambient temperature). The coating composition may be substantially free (less than 1 wt% based on total solids of the coating system) of unreacted isocyanate. The coating composition may be free of unreacted isocyanate (0 wt% based on total solids of the coating system). As used herein, "unreacted isocyanate" refers to a molecule having at least one-n=c=o group at ambient temperature. The blocked isocyanates described herein do not constitute "unreacted isocyanates" because at ambient temperature, blocked isocyanates include isocyanate reaction products that are stable at room temperature (isocyanates that react with blocked groups) and whose isocyanate functionality regenerates when their blocked groups are released at elevated temperatures.

The coating system may have a Volatile Organic Content (VOC) of less than 420g/L, such as less than 400g/L, less than 350g/L, or less than 300g/L, based on the total volume of the coating system. The VOC herein exclude water and are measured according to ASTM D3960. The measured VOC refers to the VOC of the coating composition that is ready for application to the substrate (such that no additional components are required to be added prior to application of the coating composition that could increase the VOC of the reported coating system).

The coating system can be applied to a substrate and cured to form a coating thereon by contacting the first component and the second component (from separate containers thereof) to form a coating composition and applying the formed coating composition to the substrate before the coating composition is fully cured (e.g., within 48, 24, 12, or 8 hours of first contacting the first component and the second component). The coating may be a continuous film formed over at least a portion of the substrate.

The coating system may be cured at a temperature of less than 140 ℃, such as less than 130 ℃, such as 127 ℃. As used herein, "curable" at a specified temperature means that the cured coating formed when the first component and the second component are contacted and applied to form a coating having a thickness of from 5 to 100 μm and baked at the specified temperature for 30 minutes achieves at least 75 MEK double rubs as measured according to ASTM D5402-15.

Substrates onto which the coating composition formed by the coating system can be applied include a wide range of substrates. For example, the coating composition of the present invention may be applied to a vehicle substrate, industrial substrate, aerospace substrate, and the like.

The vehicle substrate may comprise a component of a vehicle. In this disclosure, the term "vehicle" is used in its broadest sense and includes all types of aircraft, spacecraft, watercraft and ground based vehicles. For example, vehicles may include, but are not limited to, aerospace substrates (components of aerospace vehicles, such as aircraft, e.g., aircraft (e.g., private aircraft and small, medium, or large commercial passenger, cargo, and military aircraft), helicopters (e.g., private, commercial, and military helicopters), aerospace vehicles (e.g., rockets and other spacecraft), and the like. Vehicles may also include ground vehicles, such as animal trailers (e.g., horse trailers), all-terrain vehicles (ATVs), cars, trucks, buses, vans, heavy equipment, tractors, golf carts, motorcycles, bicycles, snowmobiles, trains, railroad vehicles, and the like. Vehicles may also include boats, such as ships, boats, air craft, and the like. The vehicle substrate may include components of a vehicle body, such as a motor vehicle hood, door, trunk, roof, etc.; such as aircraft or spacecraft wings, fuselages, etc.; such as a ship hull.

The coating composition may be applied to industrial substrates, which may include tools, heavy equipment, furniture (e.g., office chairs, tables, filing cabinets, etc.), household appliances (e.g., refrigerators, ovens and ranges, dishwashers, microwave ovens, washing machines, dryers, small household appliances (e.g., coffee machines, slow cookers, autoclaves, blenders, etc.), metal hardware, extruded metal (e.g., extruded aluminum for window frames, other indoor and outdoor metal building materials, etc.).

The coating composition can be applied to storage tanks, windmills, nuclear power plant parts, packaging substrates, wooden floors and furniture, clothing, electronic equipment (including housings and circuit boards), glass and transparencies, sports equipment (including golf balls), stadiums, buildings, bridges, and the like.

The substrate may be metallic or non-metallic. Metal substrates include, but are not limited to, tin, steel (including electrogalvanized steel, cold rolled steel, hot dip galvanized steel), aluminum alloys, zinc-aluminum alloys, steel coated with zinc-aluminum alloys, and aluminized steel. Nonmetallic substrates include polymeric materials, plastics and/or composites, polyesters, polyolefins, polyamides, cellulosics, polystyrenes, polyacrylic acids, poly (ethylene naphthalate), polypropylene, polyethylene, nylon, ethylene vinyl alcohol copolymers (EVOH), polylactic acid, other "green" polymeric substrates, poly (ethylene terephthalate) (PET), polycarbonates, polycarbonate-propylene-butadiene-styrene copolymers (PC/ABS), wood, plywood, wood composites, particle board, medium density fiberboard, cement, stone, glass, paper, cardboard, textiles, synthetic and natural leather, and the like. The substrate may comprise metal, plastic and/or composite materials, and/or fibrous materials. The fibrous material may comprise nylon and/or thermoplastic polyolefin material with continuous strands or chopped carbon fibers. The substrate may be a substrate that has been treated in some way, such as to impart a visual and/or color effect, a protective pretreatment or other coating, etc.

The coating composition formed from the coating system of the present invention may be particularly advantageous when applied to a metal substrate. The coatings of the present invention may be particularly advantageous when applied to metal substrates used in the manufacture of automotive vehicles, such as cars, trucks and tractors.

A coating composition formed from the coating system can be applied to a substrate having a plurality of components, wherein the coating composition is applied to the plurality of components simultaneously and cured simultaneously to form a coating on the plurality of components without deforming, distorting, or otherwise degrading any of the components. These components may be part of a larger whole of the substrate. These components may be formed separately and subsequently arranged together to form the substrate. These components may be integrally formed to form a substrate.

Non-limiting examples of components of the substrate in the context of a vehicle include a vehicle body (e.g., made of metal) and a vehicle bumper (e.g., made of plastic), which are separately formed and subsequently arranged to form the substrate of the vehicle. Further examples include plastic automotive parts, such as bumpers or fascia, where the bumper or fascia contains regions or sub-parts that contain regions or sub-parts of more than one type of substrate. Further examples include aerospace or industrial components that contain more than one substrate type. It should be understood that other such other multicomponent substrates are contemplated in the context of the present disclosure.

The plurality of components may include at least a first component and a second component, and the first component and the second component may be formed of different materials. As used herein, "different materials" refers to materials used to form a first component and a second component having different chemical compositions.

The different materials may be from the same or different classes of materials. As used herein, "class of materials" refers to materials that may have different specific chemical compositions but share the same or similar physical or chemical characteristics. For example, metals, polymers, ceramics, and composites may be defined as different classes of materials. However, other classes of materials, such as nanomaterials, biological materials, semiconductors, etc., may be defined based on the similarity of physical or chemical properties. Classes of materials may include crystalline, semi-crystalline, and amorphous materials. The class of materials as used for the polymer may include thermosets, thermoplastics, elastomers, and the like. Classes of materials such as those used for metals may include alloys and non-alloys. As will be appreciated from the exemplary class list described above, other relevant classes of materials may be defined based on a given physical or chemical property of the material.

The first component may be formed of metal and the second component may be formed of plastic or a composite material. The first component may be formed of plastic and the second component may be formed of metal or a composite material. The first component may be formed of a composite material and the second component may be formed of a plastic or metal. The first component may be formed of a first metal and the second component may be formed of a second metal different from the first metal. The first component may be formed from a first plastic and the second component may be formed from a second plastic different from the first plastic. The first component may be formed from a first composite material and the second component may be formed from a second composite material different from the first composite material. As will be appreciated from these non-limiting examples, any combination of different materials from the same or different classes may form the first and second components of the substrate.

Examples of material combinations include Thermoplastic Polyolefin (TPO) and metal, TPO and acrylonitrile-butadiene-styrene (ABS), TPO and acrylonitrile-butadiene-styrene/polycarbonate blends (ABS/PC), polypropylene and TPO, TPO and fiber reinforced composites, and other combinations. Further examples include aerospace substrates or industrial substrates comprising various components made from a variety of materials, such as various metal-plastics, metal-composites, and/or components comprising plastic-composites. The metal may include ferrous and/or non-ferrous metals. Non-limiting examples of nonferrous metals include aluminum, copper, magnesium, zinc, and the like, and alloys comprising at least one of these metals. Non-limiting examples of ferrous metals include iron, steel, and alloys thereof.

When the coating composition is applied simultaneously to a substrate having multiple components, the applied coating composition may be cured at a temperature that does not deform, distort or otherwise degrade either of the first and second components (materials thereof). Thus, the curing temperature may be below a temperature at which the first or second component of the substrate will deform, distort or otherwise degrade.

The coating composition formed from the coating system may be applied to the substrate by any suitable means, such as spraying, electrostatic spraying, dipping, roll coating, brush coating, and the like.

The coating composition formed from the coating system can be applied to a substrate to form a colored top coat. The colored top coat may be the uppermost coat so as not to include a clear coat or any other coating thereon. The colored overcoat layer can be applied directly to the substrate. The pigmented topcoat may be applied over the primer layer or pretreatment layer.

The coating composition formed from the coating system may be applied to the substrate as a coating of a multi-layer coating system such that one or more additional coatings are formed beneath and/or above the coating formed from the coating composition.

The coating composition formed from the coating system may be applied to a substrate as a primer coating for a multilayer coating system. "primer coating" refers to an inner coating that can be deposited onto a substrate (e.g., directly or on a pretreatment layer) to prepare a surface for application of a protective or decorative coating system.

The coating composition formed from the coating system may be applied to a substrate as a primer layer of a multilayer coating system. "basecoat" refers to a coating deposited onto a primer covering a substrate and/or directly onto a substrate, optionally including components (e.g., pigments) that affect color and/or provide other visual impact. A clear coat may be applied over the basecoat.

The coating composition formed from the coating system may be applied to a substrate as an overcoat to a multilayer coating system. "topcoat" refers to the uppermost coating layer deposited over another coating layer (e.g., base coat layer) to provide a protective and/or decorative layer (e.g., colored topcoat as previously described).

The top coat used with the multilayer coating system may be a clear coat, such as a clear coat applied over a base coat. As used herein, "transparent coating" refers to a coating that is at least substantially transparent or completely transparent. The term "substantially transparent" refers to a coating in which the surface beyond the coating is at least partially visible to the naked eye when viewed through the coating. The term "completely transparent" refers to a coating in which the surface beyond the coating is completely visible to the naked eye when viewed through the coating. It should be understood that the clearcoat layer may contain colorants, such as pigments, provided that the colorants do not interfere with the desired transparency of the clearcoat layer. The clear coat layer may be substantially free or pigment free.

The coating composition formed from the coating system may be applied to a substrate as a layer in a multilayer coating system. In a multilayer coating system, a first basecoat can be applied over at least a portion of the substrate, wherein the first basecoat is formed from a first basecoat composition. A second primer layer can be applied over at least a portion of the first primer layer, wherein the second primer layer is formed from a second primer layer composition. The second basecoat layer may be applied after the first basecoat composition has been cured to form the first basecoat layer, or may be applied in a wet-on-wet process prior to curing the first basecoat composition, after which the first and second basecoat compositions are cured simultaneously to form the first and second basecoat layers.

At least one of the first primer composition and the second primer composition may be a coating composition formed from the coating system of the present invention. The first primer composition and the second primer composition may be the same composition, wherein both the first primer composition and the second primer composition comprise the coating composition of the present invention. The first primer composition and the second primer composition may be different, only one of the first primer composition and the second primer composition comprising the coating composition of the present invention.

The multilayer coating system may include a primer coating formed from a primer composition applied to a substrate. The first basecoat layer may be disposed over at least a portion of the primer coating layer.

The multilayer coating system can include an overcoat formed from an overcoat composition applied to a substrate. The overcoat composition can be applied over at least a portion of the second primer layer. The overcoat layer may be a clear coat layer. The clearcoat layer may be a coating composition formed from the coating system of the present invention.

A substrate having a multilayer coating system applied thereto can be prepared by applying a first basecoat composition to at least a portion of the substrate and applying a second basecoat composition directly to at least a portion of the first basecoat composition. The first primer composition and the second primer composition may be cured simultaneously to form the first primer and the second primer. At least one of the first primer composition and the second primer composition may comprise a coating composition formed from the coating system of the present invention.

Preparing the multilayer coating system can include forming a primer coating on at least a portion of the substrate and applying a first basecoat composition over at least a portion of the primer coating.

Preparing the multilayer coating system can include applying an overcoat composition to at least a portion of the second basecoat composition. The overcoat composition (e.g., clear coat composition) can be applied to the second basecoat composition either before or after curing the first basecoat composition and the second basecoat composition. The first primer composition, the second primer composition, and the topcoat composition may be cured simultaneously. The overcoat composition can comprise a coating composition formed from the coating system of the present invention, while the first and second basecoats are different from the coating composition formed from the coating system of the present invention.

The two-component coating systems described herein can be prepared by preparing a first component as described herein and filling a first container with the first component. The two-component coating system can be prepared by preparing a second component as described herein and filling a second container, different from the first container, with the second component. The first and second containers may be arranged such that the first and second components do not contact each other until a user is ready to apply a coating composition prepared from the coating system to a substrate. To prepare the coating composition from the coating system, a user may contact a first component from a first container with a second component from a second container to form the coating composition, such as by mixing the first component with the second component. The coating composition can be applied to a substrate and cured to form a cured coating on the substrate. The coating composition (mixture of the first component and the second component) may be applied to the substrate within 48 hours, such as within 24 hours, within 12 hours, or within 8 hours, after the first contact of the first component with the second component.

Examples

The following examples are given to illustrate the general principles of the invention. The present invention should not be considered limited to the particular examples presented. All parts and percentages in these examples are by weight unless otherwise indicated.

Examples A to F

Preparation of acid functional acrylic polymers

A 300mL electrically heated continuously stirred tank reactor with internal cooling coils was filled with 2-butoxyethanol and the temperature was adjusted to the set temperature from table 1. The first reactor charge from table 1 below was fed from the feed tank to the reactor at 60 mL/min, resulting in a residence time of 5 minutes. The reactor was kept full in volume at pressures of 200 to 300 psi. The temperature is kept constant at the set temperature. The reactor output was discharged into a waste vessel during the first 15 minutes and then transferred to a 4000mL continuously stirred tank reactor equipped with a pressure relief valve set to vent at 35 psi. At this point, the second reactor charge is fed to the second reactor at a rate that matches the initiator level. The contents of the second reactor were maintained at the set temperatures of table 1. When 2230mL of product had been added to the second reactor, the outlet valve was opened and the resin was fed into the collection vessel at a rate that maintained a constant fill level, yielding a residence time of 30 minutes. The collected resin was diluted to 35% solids in water and Dimethylethanolamine (DMEA) was added to match the theoretical% neutralization from table 1.

TABLE 1

¹ Dipropylene glycol methyl ether solvent commercially available from American Dow chemical company (Dow Chemical Company) of Midland (Midland, mich.)

The properties of polymers a to F are summarized in table 2. The acid number is reported as mgKOH/g based on resin solids and is determined as described previously. Mn and Mw were determined as described previously. Tg was calculated using Fox equation.

TABLE 2

	Comparative Polymer A	Polymer B	Polymer C	Polymer D	Polymer E	Polymer F
							Mw	4899	6421	4155	5350	4664	3510
Mn	1794	2293	1837	1372	712	943
							Polydispersities (polydispersities)	2.7	2.8	2.3	3.9	6.6	3.7
Acid value	69.0	142.1	174.5	209.3	225.5	264.2
							Calculated Tg (. Degree. C.)	34.5	33.0	33.0	39.6	39.6	46.9

Comparative example G

Preparation of acid functional small molecules

57.7g of citric acid was dissolved in 107.16g of deionized water to form a clear solution.

Comparative example H

Preparation of acid functional small molecules

44.7g of trimethylolpropane and 168.19g of methyl hexahydrophthalic anhydride were added to a four-necked round bottom flask. The mixture was gradually heated to 160 ℃. The reaction was monitored by IR. Once the IR peak at 1777cm-1 of the anhydride had disappeared, the reaction was cooled to 80 ℃. A charge of 53.46g dimethylethanolamine and 332.71g deionized water was added to the flask via an addition funnel to give the final product as a clear solution.

Examples 1 to 8

Preparation and evaluation of acid-epoxy coating compositions Using the same epoxy resin

Various coating compositions were prepared by mixing the formulations described in table 3; all compositions were adjusted to the same acid to epoxy equivalent ratio. The coating composition was then applied using an 8 mil BYK knife bar to a steel plate pre-coated with an electrodeposited primer ED6280Z (available from PPG Industries, inc., pittsburgh, PA). After flashing at room temperature for 10 minutes, the plate was baked at 127 ℃ for 30 minutes.

TABLE 3 Table 3

² ACHWL CER 4221: cycloaliphatic epoxy resins available from Achiewell Limited liability company (Achiewell, LLC) of North Wales, pa

After removal from the oven, the panels were stored for 24 hours at ambient conditions and then tested for solvent resistance (methyl ethyl ketone (MEK) double rub, according to ASTM D5402-15 published by 6-1-2015), where 150 MEK double rubs are the maximum number of rubs tested. Hardness was measured according to ISO 14577-4:2016 using the Fizeaer technology (Fischer Technologies) H100C microhardness measurement system, the higher the hardness value the better. The solvent resistance and hardness properties of the blade are shown in Table 4.

TABLE 4 Table 4

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MEK and hardness tests of N/a-comparative examples 7 and 8 were not sufficiently performed because the coating composition was still wet and a cured film was not formed.

As shown in table 4, the coatings using the acid functional polymers of the present invention exhibited higher hardness. In addition, coatings using the acid functional polymers of the present invention also exhibit better solvent resistance.

Examples 9 to 17

Preparation and evaluation of acid-epoxy coating compositions Using different types of epoxy resins

Various coating compositions were prepared by mixing the formulations described in table 5; all compositions were adjusted to the same acid to epoxy equivalent ratio. The coating composition was then applied using a 5 mil BYK knife coater on a steel plate pre-coated with electrodeposited ED6100c and powder primer PCV70500 (available from PPG industries, inc. Of pittsburgh, pa). After flashing at room temperature for 10 minutes, the plate was baked at 127 ℃ for 30 minutes.

TABLE 5

³ Ai Lai Da (ARALDITE) CY 184: low viscosity cycloaliphatic epoxy resins are available from hensi mez (Huntsman Corporation) of Woodlands, TX, texas.

⁴ HELOXY 107: diglycidyl ether of cyclohexanedimethanol, commercially available from Van Inc. (Hexion Inc.)

⁵ EPODIL 749: neopentyl glycol diglycidyl ether, commercially available from Yingchuang corporation (Evonik Corporation) of Allentown, pa

⁶ ERISYS GE-21: epoxidized butanediol available from Hensmei corporation of Wydland, texas ⁷ D.e.n.431 epoxy novolac resin: semi-solid reaction products of epichlorohydrin and phenol-formaldehyde novolacs available from the American Dow chemical company of Midland, michigan

⁸ EPONEX 1510: a medium viscosity hydrogenated DPP epoxy resin available from Van Inc. of Columbus, ohio

⁹ EPON Resin 828: undiluted transparent difunctional bisphenol A/epichlorohydrin derived liquid epoxy resin available from Van Inc. of Columbus, ohio

¹⁰ Classical dibasic ester solvents, commercially available from the sor group of Brussels (bergium) Belgium (Solvay s.a.)

¹¹ Carbon black, commercially available from European technology charcoal company (Orion Engineered Carbons) of Houston, tex

¹² Defoamer, BYK available from Wesel, germany

The solvent resistance, hardness and appearance properties of the coatings are shown in table 6. Gloss (20 °) was measured according to ASTM D523. DOI was measured according to ASTM D5767.

TABLE 6

The coating compositions of examples 9 to 17 all exhibited good solvent resistance and hardness characteristics. Certain compositions also have high gloss and DOI characteristics (e.g., examples 14-16) and may be particularly suitable for use as high gloss top coats. Other examples provide good coating compositions based on solvent resistance and hardness data and may be suitable for use as a low gloss top coat or as another coating in a multi-layer coating system.

Examples 18 to 26

Preparation and evaluation of acid-epoxy coating compositions prepared as one-component and two-component systems

Representative a-and B-formulations of the two-part acid-epoxy formulations were formulated as shown in table 7. To evaluate the properties of the coating composition as a one-component formulation, the a-and B-groups were combined at t=0 hours, as shown in table 8. Samples were taken from the mixture at various time points (0, 2, 4, 24, 48, and 168 hours) after mixing and applied to steel plates pre-coated with electrodeposited primer ED6280Z (available from PPG industries, inc. Of pittsburgh, pa) using a 5 mil BYK doctor blade bar. The CAP viscosity of the combined formulation was also measured at 23 ℃ at 300rpm using a bohler fly (Brookfield) CAP 2000 viscometer with a #4 spindle at each time point. To evaluate the coating composition as a two-component formulation, as shown in table 8, at t=48 and 168 hours, the a-and B-formulations were combined together in the same ratio as the one-component formulation. The coating composition was applied immediately after mixing and the viscosity was measured in the same manner as for the one-component formulation. After application, all plates were flashed at room temperature for 10 minutes and then baked at 127 ℃ for 30 minutes.

TABLE 7

TABLE 8

After removal from the oven, the panels were stored at ambient conditions for 24 hours and then tested for solvent resistance, hardness, gloss and DOI as described in the previous examples. The characteristics of each plate are shown in tables 9 and 10.

Immediately after mixing the a-and B-formulations in example 21 (t=0 hours), the coating composition had acceptable application viscosity and high gloss, DOI, fexil microhardness and solvent resistance. The gloss and DOI of example 21 were significantly reduced when applied after 24 hours of standing the mixture in combination and the viscosity of the combined formulation was more than doubled within 48 hours. If the a-and B-formulations were treated as two-component systems and mixed together immediately prior to application (examples 23 and 25), the viscosity, solvent resistance, fizeal microhardness, gloss and DOI of the coating at t=48 and 168 hours were similar to the properties of the coating at t=0 hours.

In table 10, the viscosity of the other a-and B-formulation combinations (example 22) treated as one-component formulations increased significantly over 168 hours. When handled as a two-component formulation and mixed immediately prior to application (examples 24 and 26), the coating composition had similar properties of viscosity, solvent resistance, phenanthrell microhardness, gloss and DOI at t=48 and 168 hours as at t=0 hours.

TABLE 9

¹³ The formulation viscosity exceeds the viscosity limit of CAP measurement.

Table 10

¹⁴ The formulation is a gel and therefore cannot be applied as a film.

While specific embodiments of the 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 invention may be made without departing from the invention as defined in the appended claims.

Claims

1. A two-component aqueous coating system comprising:

a first component comprising an acid functional polymer dispersed in an aqueous medium, the acid functional polymer having an acid number of at least 100 based on total resin solids; and

a second component separate from the first component, wherein the second component comprises an epoxy functional compound.

2. The coating system of claim 1, wherein forming a coating from the coating system comprises contacting the first component with the second component.

3. The coating system of claim 1 or 2, wherein the acid functional polymer has an acid number of at least 130 on a total resin solids basis.

4. A coating system according to any one of claims 1 to 3, wherein the acid functional polymer has a weight average molecular weight of at least 2,000, such as from 2,000 to 20,000.

5. The coating system of any one of claims 1 to 4, wherein the acid functional polymer has a Tg of from-40 ℃ to 80 ℃, such as from 20 ℃ to 60 ℃ or from 25 ℃ to 50 ℃.

6. The coating system of any one of claims 1 to 5, wherein the acid functional polymer comprises an acrylic polymer.

7. The coating system of any one of claims 1 to 6, wherein the epoxy functional compound has a weight average molecular weight of up to 2,000, such as from 180 to 2,000.

8. The coating system of any one of claims 1 to 7, wherein the epoxy functional compound comprises a cycloaliphatic epoxy resin, an aliphatic epoxy resin, a hexahydrophthalic anhydride diester epoxy resin, a cyclohexanedimethanol based epoxy resin, a neopentyl glycol based epoxy resin, a polyglycidyl ether epoxy resin, an aromatic multifunctional epoxy resin, a bisphenol a diepoxide, a hydrogenated bisphenol a diepoxide, a triglycidyl ether of trimethylolpropane, or some combination thereof.

9. The coating system of any one of claims 1 to 8, further comprising a neutralizing amine.

10. The coating system of claim 9, further comprising a catalyst different from the neutralizing amine.

11. The coating system of any one of claims 1 to 10, further comprising a crosslinker comprising an aminoplast, a blocked isocyanate, a silane, an oxazoline, a carbodiimide, or some combination thereof.

12. The coating system of any one of claims 1 to 11, wherein the coating system is substantially pigment-free, such as comprising less than 3 wt% pigment based on total solids of the coating system.

13. The coating system of any one of claims 1 to 12, wherein the coating system is substantially free of unreacted isocyanate, such as comprising less than 5 wt% unreacted isocyanate based on total solids of the coating system.

14. The coating system of any one of claims 1 to 13, wherein the second component is substantially free of water, such as comprising less than 5 wt% water based on the total weight of components in the second component.

15. The coating system of any one of claims 1 to 14, wherein the coating system has a Volatile Organic Content (VOC) of less than 420g/L, based on the total volume of the coating system, excluding water and measured according to ASTM D3960.

16. The coating system of any one of claims 1 to 15, wherein the layer achieves at least 75 MEK double rubs measured according to ASTM D5402-15 when the first component is contacted with the second component by baking at 127 ℃ for 30 minutes to form a layer having a thickness of 5 to 100 μιη.

17. The coating system of any one of claims 1 to 16, wherein the ratio of acid groups to epoxy groups in the coating system ranges from 1.5:1 to 1:1.5, such as from 1.2:1 to 0.9:1 or from 1.1:1 to 1:1.1.

18. The coating system of any one of claims 1 to 17, wherein the first component and the second component are contained in separate containers prior to any mixing of the first component and the second component.

19. The coating system of any one of claims 1 to 18, wherein the second component further comprises a second epoxy functional compound.

20. The coating system of claim 19, wherein the second epoxy functional compound comprises an epoxy functional acrylic.

21. A substrate at least partially coated with a coating composition formed from the coating system according to any one of claims 1 to 20.

22. The substrate of claim 21, wherein the substrate comprises a vehicle substrate.

23. A method of preparing the two-component aqueous coating system of any one of claims 1 to 20, comprising:

preparing a first component comprising an acid functional polymer dispersed in an aqueous medium, the acid functional polymer having an acid number of at least 100 based on total resin solids;

filling a first container with the first component;

preparing a second component, wherein the second component comprises an epoxy functional compound; and

filling a second container different from the first container with the second component.

24. The method of claim 23, further comprising mixing the first component from the first container with the second component from the second container to form a coating composition capable of being applied on a substrate to form a cured coating on the substrate.

25. The method of claim 24, wherein the mixture of the first component and the second component is applied to the substrate within 48 hours of the mixing.

26. The method of any one of claims 23 to 25, wherein the first component is prepared in a continuous stirred tank reactor.

27. A two-component aqueous coating system kit of the two-component aqueous coating system according to any one of claims 1 to 20, comprising:

a first vessel comprising a first component comprising an acid functional polymer dispersed in an aqueous medium, the acid functional polymer having an acid number of at least 100 based on total resin solids; and

a second container separate from the first container, wherein the second container comprises a second component comprising an epoxy functional compound.

28. The kit of claim 27, wherein the second container is substantially free of water, such as less than 5 wt% water based on the total weight of components in the second component.

29. The kit of claim 27 or 28, wherein the second component is not in contact with the first component in the kit.