WO2022039927A1

WO2022039927A1 - One-component waterborne polyurethane self-healing coatings using hydrophobic blocked polyisocyanates

Info

Publication number: WO2022039927A1
Application number: PCT/US2021/044490
Authority: WO
Inventors: Makoto Nakao
Original assignee: Covestro Llc
Priority date: 2020-08-18
Filing date: 2021-08-04
Publication date: 2022-02-24

Abstract

Provided is a coating comprising a waterborne polyurethane comprising an aliphatic, hydrophobic polyisocyanate and an aliphatic polyurethane dispersion, wherein the aliphatic, hydrophobic polyisocyanate is blocked with a blocking agent, wherein the coating is self-healing defined as having a gloss retention of at least 90% at 20° and 60° after scratching with steel wool and heating to 60°C for two hours, and wherein the coating has a similar final film hardness at a shorter drying time to a comparable waterborne polyurethane comprising an aliphatic, hydrophilic polyisocyanate and the same aliphatic polyurethane dispersion. The one-component waterborne polyurethane coatings have a higher productivity (faster cure), comparable self-healing performance, and final film hardness as two-component, waterborne polyurethane self-healing coatings.

Description

ONE-COMPONENT WATERBORNE POLYURETHANE SELF-HEALING COATINGS USING HYDROPHOBIC BLOCKED POLYISOCYANATES

FIELD OF THE INVENTION

[0001] The present invention relates in general to coatings, and more specifically, to one- component waterborne polyurethane, self-healing coatings made with hydrophobic, blocked polyisocyanates.

BACKGROUND OF THE INVENTION

[0002] Polymeric materials are used in a wide variety of applications. A recurring issue with polymeric materials is that such materials are susceptible to failure or degradation due to mechanical fatigue, mechanical impact, oxidative aging, thermal fatigue, chemical degradation, or a combination of these processes. Polymer degradation can lead to embrittlement and associated cracking. Mechanical fatigue and mechanical stress may also lead to cracks in the polymeric material. If cracks occur in a polymeric coating on a metal surface, the underlying metal surface may be exposed to the elements and be subject to corrosion. A potential solution to such issues is provided by so called “self-healing” coatings.

[0003] Self-healing refers to a characteristic of the coating that permits damage inflicted to the coating by an external physical force or stimulus, such as a scratch, to heal or repair. Although various self-healing coating materials or self-healing methods are known in the art, elastic coating materials are typically used. Such coatings allow the damaged region to be gradually filled due to the elasticity of the coating material itself.

[0004] However, these conventional self-healing coating materials have a disadvantage in that the mechanical properties e.g., hardness, abrasion resistance, coating strength, are insufficient, as elastic materials are mostly used as contents of the self-healing coating layer. Thus, if a strong external stimulus is applied to the existing coating layer, the coating layer itself may be permanently damaged and even lose the self-healing characteristic. Some in the art have suggested using two-component polyurethane coatings. Among the drawbacks of such coatings are the need to keep the components separate until used and the difficulty in mixing the components properly.

[0005] Thus, a need continues to exist in the art for a one-component self-healing coating which is fast curing and has a final film hardness comparable to two-component, waterborne polyurethane self-healing systems. SUMMARY OF THE INVENTION

[0006] Accordingly, the present invention reduces or eliminates problems inherent in the art by providing a one-component waterborne polyurethane system with higher productivity (faster cure), comparable self-healing performance, and final film hardness compared to two- component, waterborne polyurethane self-healing systems.

[0007] These and other advantages and benefits of the present invention will be apparent from the Detailed Description of the Invention herein below.

DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will now be described for purposes of illustration and not limitation. Except in the operating examples, or where otherwise indicated, all numbers expressing quantities, percentages, and so forth in the specification are to be understood as being modified in all instances by the term “about.”

[0009] Any numerical range recited in this specification is intended to include all sub-ranges of the same numerical precision subsumed within the recited range. For example, a range of “1.0 to 10.0” is intended to include all sub-ranges between (and including) the recited minimum value of 1.0 and the recited maximum value of 10.0, that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limitation recited in this specification is intended to include all lower numerical limitations subsumed therein and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein.

Accordingly, Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range subsumed within the ranges expressly recited herein. All such ranges are intended to be inherently described in this specification such that amending to expressly recite any such sub-ranges would comply with the requirements of 35 U.S.C. § 112(a), and 35 U.S.C. § 132(a). The various embodiments disclosed and described in this specification can comprise, consist of, or consist essentially of the features and characteristics as variously described herein.

[0010] Any patent, publication, or other disclosure material identified herein is incorporated by reference into this specification in its entirety unless otherwise indicated, but only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material expressly set forth in this specification. As such, and to the extent necessary, the express disclosure as set forth in this specification supersedes any conflicting material incorporated by reference herein. Any material, or portion thereof, that is said to be incorporated by reference into this specification, but which conflicts with existing definitions, statements, or other disclosure material set forth herein, is only incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. Applicant reserves the right to amend this specification to expressly recite any subject matter, or portion thereof, incorporated by reference herein.

[0011] Reference throughout this specification to “various non-limiting embodiments,” “certain embodiments,” or the like, means that a particular feature or characteristic may be included in an embodiment. Thus, use of the phrase “in various non-limiting embodiments,” “in certain embodiments,” or the like, in this specification does not necessarily refer to a common embodiment, and may refer to different embodiments. Further, the particular features or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features or characteristics illustrated or described in connection with various or certain embodiments may be combined, in whole or in part, with the features or characteristics of one or more other embodiments without limitation. Such modifications and variations are intended to be included within the scope of the present specification.

[0012] The grammatical articles “a”, “an”, and “the”, as used herein, are intended to include “at least one” or “one or more”, unless otherwise indicated, even if “at least one” or “one or more” is expressly used in certain instances. Thus, these articles are used in this specification to refer to one or more than one (i.e., to “at least one”) of the grammatical objects of the article. By way of example, and without limitation, “a component” means one or more components, and thus, possibly, more than one component is contemplated and may be employed or used in an implementation of the described embodiments. Further, the use of a singular noun includes the plural, and the use of a plural noun includes the singular, unless the context of the usage requires otherwise.

[0013] In a first aspect, the invention is directed to coating comprising a waterborne polyurethane comprising an aliphatic, hydrophobic polyisocyanate and an aliphatic polyurethane dispersion, wherein the aliphatic, hydrophobic polyisocyanate is blocked with a blocking agent, wherein the coating is self-healing defined as having a gloss retention of at least 90% at 20° and 60° after scratching with steel wool and heating to 60°C for two hours, and wherein the coating has a similar final film hardness at a shorter drying time to a comparable waterborne polyurethane comprising an aliphatic, hydrophilic polyisocyanate and the same aliphatic polyurethane dispersion.

[0014] In a second aspect, the invention is directed to a process of producing a coating comprising combining (A) a waterborne polyurethane comprising (Al) an aliphatic, hydrophobic polyisocyanate, and (A2) an aliphatic polyurethane dispersion, wherein the aliphatic, hydrophobic polyisocyanate is blocked with a blocking agent; and (B) curing the waterborne polyurethane to form a coating, wherein the coating is self-healing defined as having a gloss retention of at least 90% at 20° and 60° after scratching with steel wool and heating to 60°C for two hours, and wherein the coating has a similar final film hardness at a shorter drying time to a comparable waterborne polyurethane comprising an aliphatic, hydrophilic polyisocyanate and the same aliphatic polyurethane dispersion.

[0015] As used herein, the term “coating composition” refers to a mixture of chemical components that will cure and form a coating when applied to a substrate. As used herein, a “coating” means a layer of any substance spread over a surface.

[0016] “Cured,” “cured composition” or “cured compound” refers to components and mixtures obtained from reactive curable original compound(s) or mixture(s) thereof which have undergone chemical and/or physical changes such that the original compound(s) or mixture(s) is(are) transformed into a solid, substantially non- flowing material. A typical curing process may involve crosslinking. Suitable crosslinking additives include, but are not limited to, polyisocyanates, aziridines, and carbodiimides.

[0017] The term “curable” means that an original compound(s) or composition material(s) can be transformed into a solid, substantially non- flowing material by means of chemical reaction, crosslinking, radiation crosslinking, or the like. Thus, compositions of the invention are curable, but unless otherwise specified, the original compound(s) or composition material(s) is(are) not cured.

[0018] As used herein, the term “paint” refers to a substance used for decorating or protecting a surface, and is typically a mixture containing a solid pigment suspended in a liquid, that when applied to a surface dries to form a hard, protective coating.

[0019] As used herein, “primer” refers to a substance used as a preparatory coat on previously an unpainted or uncoated surface to prevent the absorption of subsequent layers of coating or paint.

[0020] As used herein, “topcoat” refers to a transparent or translucent coat applied over the underlying material as a sealer. In a paint system, the topcoat provides a seal over the intermediate coat(s) and the primer.

[0021] As used herein, the term “polyurethane” refers to polymeric or oligomeric materials comprising urethane groups, urea groups, or both. Accordingly, as used herein, the term “polyurethane” is synonymous with the terms polyurea, polyurethane/urea, and modifications thereof. The term “polyurethane” also refers to crosslinked polymer networks in which the crosslinks comprise urethane and/or urea linkages, and/or the constituent polymer chains comprise urethane and/or urea linkages.

[0022] As used herein, the term “polyol” refers to compounds comprising at least two free hydroxyl groups. Polyols include polymers comprising pendant and terminal hydroxyl groups.

[0023] As used herein, “polymer” encompasses prepolymers, oligomers and both homopolymers and copolymers; the prefix “poly” in this context referring to two or more. As used herein, “molecular weight”, when used in reference to a polymer, refers to the number average molecular weight (“M_n”), unless otherwise specified. As used herein, the M_n of a polymer containing functional groups, such as a polyol, can be calculated from the functional group number, such as hydroxyl number, which is determined by end-group analysis.

[0024] As used herein, the term “aliphatic” refers to organic compounds characterized by substituted or un-substituted straight, branched, and/or cyclic chain arrangements of constituent carbon atoms. Aliphatic compounds do not contain aromatic rings as part of the molecular structure thereof. As used herein, the term “cycloaliphatic” refers to organic compounds characterized by arrangement of carbon atoms in closed ring structures. Cycloaliphatic compounds do not contain aromatic rings as part of the molecular structure thereof. Therefore, cycloaliphatic compounds are a subset of aliphatic compounds. Therefore, the term “aliphatic” encompasses aliphatic compounds and cycloaliphatic compounds.

[0025] Suitable aliphatic polyisocyanate include, but are not limited to, 1 ,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate (PDI), 1,6-hexamethylene diisocyanate (HD I), 2,2,4-trimethyl-hexamethylene diisocyanate, dodecamethylene diisocyanate, 2-methyl-l,5- diisocyanatopentane, 1 ,4-diisocyanatocyclohexane, 5-isocyanato-l-(isocyanatomethyl)- 1,3,3- trimethylcyclohexane (IPDI), 2,4-diisocyanato-dicyclohexyl-methane, 4,4'-diisocyanato- dicyclohexyl-methane, 1,3-bis (isocyanatomethyl)-cyclohexane, 1,4-bis (isocyanatomethyl)- cyclohexane, l-isocyanato-l-methyl-3(4)-isocyanatomethyl-cyclohexane (IMCI), bis(4- isocyanato-3-methyl-cyclohexyl)-methane, 1 ,4-cyclohexane diisocyanate (CHDI), trimers, isocyanurates, uretdiones, biurets, allophanates, iminooxadiazine diones, carbodiimides, oxadiazine triones, and prepolymers of any of these, and mixtures thereof.

[0026] As used herein, the term “dispersion” refers to a composition comprising a discontinuous phase distributed throughout a continuous phase. For example, "’’waterborne dispersion” and “aqueous dispersion” refer to compositions comprising particles or solutes distributed throughout liquid water. Waterborne dispersions and aqueous dispersions may also include one or more co-solvents in addition to the particles or solutes and water. As used herein, the term “dispersion” includes, for example, colloids, emulsions, suspensions, sols, solutions (i.e., molecular or ionic dispersions), and the like.

[0027] As used herein, the term “aqueous polyurethane dispersion” means a dispersion of polyurethane particles in a continuous phase comprising water. As used herein, the term “polyurethane” refers to any polymer or oligomer comprising urethane (i.e., carbamate) groups, urea groups, or both. Thus, the term “polyurethane” as used herein refers collectively to polyurethanes, polyureas, and polymers containing both urethane and urea groups, unless otherwise indicated. Aqueous polyurethane dispersions are described, for example, in U.S. Pat. Nos. 4,857,565; 4,921,842; 5,177,141; 6,147,155; and 6,284,836, the entire contents of which are incorporated herein by reference.

[0028] As used herein, the term “waterborne” refers to a composition which contains water as its primary liquid component.

[0029] As used herein, the term “hydrophilic isocyanate” means an isocyanate containing polyethylene oxide groups, sulfonate salt groups, or the like. Such isocyanates may also be selected from dimers, trimers, adducts, polymeric and prepolymeric isocyanates. Suitable hydrophilic isocyanates are commercially available from companies such as Covestro, BASF, ICI, Dow, Huntsman, and Degussa. For example, suitable commercial products include those sold under the BAHYDUR tradename, which are available from Covestro.

[0030] “Hydrophobic isocyanates” include, but are not limited to, di-cyclohexylmethane- 4,4'-diisocyanate, isophorone diisocyanate, xylene diisocyanate, cyclohexane diisocyanate, hexamethylene diisocyanate, tetramethylxylene diisocyanate and oligomeric hexamethylene diisocyanate. Trade names include DESMODUR W and DESMODUR I, available from Covestro LLC. The hydrophobic isocyanate has two or more isocyanate groups, i.e. the isocyanate may be selected from dimers, trimers, adducts, polymeric and prepolymeric isocyanates. The hydrophobic isocyanate may include aromatic isocyanates, aliphatic isocyanates, or combinations thereof. Nonlimiting examples of suitable aromatic isocyanates include toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, 4,4'-methylene diphenyl diisocyanate, 2,4'-methylene diphenyl diisocyanate, polymeric methylene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, naphthalene 1,5-diisocyanate, naphthalene 2,4- diisocyanate, 1,5 -naphthalene diisocyanate, p-xylylene diisocyanate, and the like. Nonlimiting examples of suitable aliphatic isocyanates include isophorone diisocyanate, 1 ,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, bis(isocyanatomethyl) cyclohexane, tetramethylxylylene diisocyanate, 1,6-hexamethylene diisocyanate, and the like. Many of these isocyanates are commercially available from companies such as Covestro, BASF, ICI, Dow, Huntsman, and Degussa.

[0031] As used herein, the term “self-healing” means the ability of a coating to heal damage caused by the application of an external physical force or stimulus, such as a scratch.

[0032] The coatings of the invention include blocked polyisocyanates. Such compounds may be obtained by blocking the isocyanate groups of any of the polyisocyanates described herein with blocking agents. A variety of disclosures provide further details regarding blocking and blocked polyisocyanates, including U.S. Pat. Nos. 5,668,238; 6,242,530; 6,586,521; 6,863,863; 7,074,852; and 7,718,729, the entire contents of which are incorporated herein by reference.

[0033] Examples of suitable blocking agents include, but are not limited to, phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, hydroxybenzoic acid methyl and other phenol compounds; g-caprolactam, 5- valerolactam, y-butyrolactam, P-propiolactam and other lactam compounds; methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol and other aliphatic alcohol compounds; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, methoxymethanol and other ether compounds; benzyl alcohol; glycolic acid; methyl glycolate, ethyl glycolate, butyl glycolate and other glycolic acid esters; lactic acid, methyl lactate, ethyl lactate, butyl lactate and other lactates; methylolurea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and other alcohol compounds; formamide oxime, acetamide oxime, acetoxime, methylethyl ketoxime, diacetyl monoxime, benzophenone oxime, cyclohexane oxime and other oxime compounds; dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone and other activated methylene compounds; butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol and other mercaptan compounds; acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetamide, stearamide, benzamide and other acid amide compounds; succinimide, phthalimide, maleimide and other imide compounds; diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenylamine and other amine compounds; imidazole, 2-ethyl imidazole and other imidazole compounds; urea, thiourea, ethylene urea, ethylenetiourea, diphenylurea and other urea compounds; N-phenyl carbamate phenyl and other carbamate compounds; ethyleneimine, propyleneimine and other imine compounds; sodium bisulfite, potassium bisulfite and other sulfite compounds; 3,5-dimethylpyrazole, 3-methylpyrazole, 4- nitro-3, 5 -dimethyl pyrazole, 4-bromo-3,5-dimethylpyrazole and the like.

[0034] The above blocking agents, which block free isocyanate groups, easily react with isocyanate groups when, for example, heated to 100°C or more, and in some embodiments of the invention to 130°C or more.

[0035] The coatings of the present invention may further include any of a variety of additives such as defoamers, devolatilizers, thickeners, flow control additives, colorants (including pigments and dyes), surfactants, dispersants, and neutralizers as is known to those skilled in the art.

[0036] The coatings of the present invention may be admixed and combined with the conventional paint-technology binders, auxiliaries and additives, selected from the group of pigments, dyes, matting agents, flow control additives, wetting additives, slip additives, pigments, including metallic effect pigments, fillers, nanoparticles, light stabilizing particles, anti-yellowing additives, thickeners, and additives for reducing the surface tension.

[0037] The coatings according to the invention can be applied to the substrate by the conventional techniques, such as, spraying, rolling, flooding, printing, knife-coating, pouring, brushing and dipping.

[0038] Although described in the present examples in the context of a coating, the principles are not to be so limited. Those skilled in the art will recognize that the principles of the present invention are equally applicable to coatings, adhesives, paints, primers, topcoats, and sealants.

EXAMPLES

[0039] The non-limiting and non-exhaustive examples that follow are intended to further describe various non-limiting and non-exhaustive embodiments without restricting the scope of the embodiments described in this specification. The following materials were used in preparing the compositions of the Examples. All quantities given in “parts” and “percents” are understood to be by weight, unless otherwise indicated.

DISPERSION A an aliphatic, hydroxyfunctional polycarbonate esterpolyurethane dispersion;

POLYISOCYANATE A a hydrophobic aliphatic polyisocyanate based on HDI, blocked with diethyl malonate (DEM)/diisopropylamine (DIPA);

POLYISOCYANATE B a hydrophilic, water-dispersible polyisocyanate based on hydrogenated diphenylmethane diisocyanate (H12MDI), blocked with methylethyl ketoxime (MEKO);

[0040] Curing conditions: 3 mil wet draw down samples were applied to steel panel substrates (CRS B952 P90 E-coat ED6060C from ACT Test Panels LLC) at three different curing temperatures; 160°C, 180°C, and 200°C. Times: 2, 3, 4, 7 and 11 minutes. Tests were conducted after additional seven days cure at ambient temperature. Pendulum hardness was measured according to ASTM D4366.

[0041] Table II summarizes the pendulum hardness data for a two-component, waterborne coating made with POLYISOCYANATE D (a hydrophilic aliphatic polyisocyanate) at three different curing temperatures; 160°C, 180°C, and 200°C.

[0042] Table III summarizes the pendulum hardness data for a one component waterborne coating made with POLYISOCYANATE C (a hydrophilic aliphatic polyisocyanate blocked with 2-methoxypropoxypropanol (DPM)) at three different curing temperatures; 160°C, 180°C, and 200°C.

[0043] Table IV summarizes the pendulum hardness data for a one component waterborne coating made with POLYISOCYANATE B (a hydrophilic aliphatic polyisocyanate blocked with methylethyl ketoxime (MEKO)) at three different curing temperatures; 160°C, 180°C, and 200°C.

[0044] Table V summarizes the pendulum hardness data for a one component waterborne coating made with POLYISOCYANATE A (a hydrophobic aliphatic polyisocyanate blocked with diethyl malonate (DEM)/diisopropylamine (DIP A)) at three different curing temperatures; 160°C, 180°C, and 200°C.

[0045] As can be appreciated by reference to Tables II and V, comparing the two-component waterborne coating in Table II made with POLYISOCYANATE D, to the one-component, waterborne coating made with POLYISOCYANATE A (Table V), the one-component coating had a comparable final film hardness at a shorter drying time.

[0046] Comparing the one-component, waterborne coatings made with hydrophilic blocked POLYISOCYANATES B and C (Tables III and IV), the one-component, waterborne coating made with POLYISOCYANATE A (Table V) had a faster hardness development and a harder final film hardness at a shorter drying time. Table II

Table III

Table IV

Table V

[0047] To evaluate the scratch resistance and the self-healing properties of the clearcoat, the gloss (20° and 60°) was measured - before scratching (initial gloss), after scratching and after self-healing at 60°C over a period of two hours. A CROCKMETER (Atlas, Model CM-5) with steel wool 000 was used to rub the coating surface and ten double rubs were conducted. Relative residual gloss to initial gloss was calculated after scratching and after self-healing.

[0048] Table VI summarizes the gloss retention at 20° and 60° before and after scratching for a two-component, waterborne coating made with POLYISOCYANATE D (a hydrophilic aliphatic polyisocyanate) at three different curing temperatures; 160°C, 180°C, and 200°C.

[0049] Table VII summarizes the gloss retention at 20° and 60° before and after scratching for a one component waterborne coating made with POLYISOCYANATE C (a hydrophilic aliphatic polyisocyanate blocked with 2-methoxypropoxypropanol (DPM)) at three different curing temperatures; 160°C, 180°C, and 200°C.

[0050] Table VIII summarizes the gloss retention at 20° and 60° before and after scratching for a one component waterborne coating made with POLYISOCYANATE B (a hydrophilic aliphatic polyisocyanate blocked with methylethyl ketoxime (MEKO)) at three different curing temperatures; 160°C, 180°C, and 200°C.

[0051] Table IX summarizes the gloss retention at 20° and 60° before and after scratching for a one component waterborne coating made with POLYISOCYANATE A (a hydrophobic aliphatic polyisocyanate blocked with diethyl malonate (DEM)/diisopropylamine (DIP A)) at three different curing temperatures; 160°C, 180°C, and 200°C.

[0052] As can be appreciated by reference to Tables VI to IX, the inventive one-component waterborne coating made with POLYISOCYANATE A (a hydrophobic aliphatic polyisocyanate blocked with diethyl malonate (DEM)/diisopropylamine (DIP A)) and summarized in Table IX, showed comparable self-healing properties to that of the two-component waterborne coating made with POLYISOCYANATE D (a hydrophilic aliphatic polyisocyanate) summarized in Table VI.

Table VI

Table VII

Table VIII

Table IX

[0053] This specification has been written with reference to various non-limiting and non- exhaustive embodiments. However, it will be recognized by persons having ordinary skill in the art that various substitutions, modifications, or combinations of any of the disclosed embodiments (or portions thereof) may be made within the scope of this specification. Thus, it is contemplated and understood that this specification supports additional embodiments not expressly set forth herein. Such embodiments may be obtained, for example, by combining, modifying, or reorganizing any of the disclosed steps, components, elements, features, aspects, characteristics, limitations, and the like, of the various non-limiting embodiments described in this specification. In this manner, Applicant reserves the right to amend the claims during prosecution to add features as variously described in this specification, and such amendments comply with the requirements of 35 U.S.C. § 112(a), and 35 U.S.C. § 132(a).

[0054] Various aspects of the subject matter described herein are set out in the following numbered clauses:

[0055] Clause 1. A coating comprising a waterborne polyurethane comprising an aliphatic, hydrophobic polyisocyanate and an aliphatic polyurethane dispersion, wherein the aliphatic, hydrophobic polyisocyanate is blocked with a blocking agent, wherein the coating is self-healing defined as having a gloss retention of at least 90% at 20° and 60° after scratching with steel wool and heating to 60°C for two hours, and wherein the coating has a similar final film hardness at a shorter drying time to a comparable waterborne polyurethane comprising an aliphatic, hydrophilic polyisocyanate and the same aliphatic polyurethane dispersion.

[0056] Clause 2. The coating according to Clause 1, wherein the aliphatic hydrophobic polyisocyanate is selected from the group consisting of di-cyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, hexamethylene diisocyanate, tetramethylxylene diisocyanate, and oligomeric hexamethylene diisocyanate.

[0057] Clause 3. The coating according to one of Clauses 1 and 2, wherein the aliphatic hydrophobic polyisocyanate is hexamethylene diisocyanate.

[0058] Clause 4. The coating according to any one of Clauses 1 to 3, wherein the blocking agent is selected from the group consisting of phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, hydroxybenzoic acid, E-caprolactam, 5-valerolactam, y-butyrolactam, P-propiolactam, methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, methoxymethanol, benzyl alcohol; glycolic acid; methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylolurea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, formamide oxime, acetamide oxime, acetoxime, methylethyl ketoxime, diacetyl monoxime, benzophenone oxime, cyclohexane oxime, dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2- mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol, acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetamide, stearamide, benzamide, succinimide, phthalimide, maleimide, diphenylamine, phenylnaphthylamine, xylidine, N- phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenylamine, imidazole, 2-ethyl imidazole, urea, thiourea, ethylene urea, ethylenetiourea, diphenylurea, biphenyl carbamate phenyl, ethyleneimine, propyleneimine, sodium bisulfite, potassium bisulfite, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-nitro-3,5-dimethyl pyrazole, 4-bromo-3,5- dimethylpyrazole, and mixtures thereof.

[0059] Clause 5. The coating according to any one of Clauses 1 to 4, wherein the blocking agent is selected from the group consisting of diethyl malonate, diisopropylamine, methylethyl ketoxime, 2-methoxypropoxypropanol, and combinations thereof.

[0060] Clause 6. The coating according to any one of Clauses 1 to 5, wherein the blocking agent is a combination of diethyl malonate and diisopropylamine.

[0061] Clause 7. The coating according to any one of Clauses 1 to 6, wherein the aliphatic polyurethane dispersion is an aliphatic, hydroxyftmctional polycarbonate ester-polyurethane dispersion.

[0062] Clause 8. A substrate having applied thereto the coating according to any one of Clauses 1 to 7.

[0063] Clause 9. A process of producing a coating comprising combining (A) a waterborne polyurethane comprising (Al) an aliphatic, hydrophobic polyisocyanate, and (A2) an aliphatic polyurethane dispersion, wherein the aliphatic, hydrophobic polyisocyanate is blocked with a blocking agent; and (B) curing the waterborne polyurethane to form a coating, wherein the coating is self-healing defined as having a gloss retention of at least _90 % at 20° and 60° after scratching with steel wool and heating to 60°C for two hours, and wherein the coating has a similar final film hardness at a shorter drying time to a comparable waterborne polyurethane comprising an aliphatic, hydrophilic polyisocyanate and the same aliphatic polyurethane dispersion. [0064] Clause 10. The process according to Clause 9, wherein the aliphatic hydrophobic polyisocyanate is selected from the group consisting of di-cyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, hexamethylene diisocyanate, tetramethylxylene diisocyanate, and oligomeric hexamethylene diisocyanate.

[0065] Clause 11. The process according to one of Clauses 9 and 10, wherein the aliphatic hydrophobic polyisocyanate is hexamethylene diisocyanate.

[0066] Clause 12. The process according to any one of Clauses 9 to 11, wherein the blocking agent is selected from the group consisting of phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, hydroxybenzoic acid, g-caprolactam, 5-valerolactam, y-butyrolactam, P-propiolactam, methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, methoxymethanol, benzyl alcohol; glycolic acid; methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylolurea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, formamide oxime, acetamide oxime, acetoxime, methylethyl ketoxime, diacetyl monoxime, benzophenone oxime, cyclohexane oxime, dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol, acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetamide, stearamide, benzamide, succinimide, phthalimide, maleimide, diphenylamine, phenylnaphthylamine, xylidine, N- phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenylamine, imidazole, 2-ethyl imidazole, urea, thiourea, ethylene urea, ethylenetiourea, diphenylurea, biphenyl carbamate phenyl, ethyleneimine, propyleneimine, sodium bisulfite, potassium bisulfite, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-nitro-3,5-dimethyl pyrazole, 4-bromo-3,5- dimethylpyrazole, and mixtures thereof.

[0067] Clause 13. The process according to any one of Clauses 9 to 12, wherein the blocking agent is selected from the group consisting of diethyl malonate, diisopropylamine, methylethyl ketoxime, 2-methoxypropoxypropanol, and combinations thereof.

[0068] Clause 14. The process according to any one of Clauses 9 to 13, wherein the blocking agent is a combination of diethyl malonate and diisopropylamine. [0069] Clause 15. The process according to any one of Clauses 9 to 14, wherein the aliphatic polyurethane dispersion is an aliphatic, hydroxyfunctional polycarbonate esterpolyurethane dispersion.

[0070] Clause 16. A substrate having applied thereto a coating made according to any one of Clauses 9 to 15.

Claims

What is claimed is:

1. A coating comprising: a waterborne polyurethane comprising an aliphatic, hydrophobic polyisocyanate; an aliphatic polyurethane dispersion; wherein the aliphatic, hydrophobic polyisocyanate is blocked with a blocking agent, wherein the coating is self-healing defined as having a gloss retention of at least 90% at 20° and 60° after scratching with steel wool and heating to 60°C for two hours, and wherein the coating has a similar final film hardness at a shorter drying time to a comparable waterborne polyurethane comprising an aliphatic, hydrophilic polyisocyanate and the same aliphatic polyurethane dispersion.

Claim 2. The coating according to claim 1, wherein the aliphatic hydrophobic polyisocyanate is selected from the group consisting of di-cyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, hexamethylene diisocyanate, tetramethylxylene diisocyanate, and oligomeric hexamethylene diisocyanate.

Claim 3. The coating according to claim 1, wherein the aliphatic hydrophobic polyisocyanate is hexamethylene diisocyanate.

Claim 4. The coating according to claim 1, wherein the blocking agent is selected from the group consisting of phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, hydroxybenzoic acid, g-caprolactam, 5- valerolactam, y-butyrolactam, P-propiolactam, methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, methoxymethanol, benzyl alcohol; glycolic acid; methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylolurea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, formamide oxime, acetamide oxime, acetoxime, methylethyl ketoxime, diacetyl monoxime, benzophenone oxime, cyclohexane oxime, dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol, acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetamide, stearamide, benzamide, succinimide, phthalimide, maleimide, diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenylamine, imidazole, 2-ethyl imidazole, urea, thiourea, ethylene urea, ethylenetiourea, diphenylurea, N-phenyl carbamate phenyl, ethyleneimine, propyleneimine, sodium bisulfite, potassium bisulfite, 3,5-dimethylpyrazole, 3- methylpyrazole, 4-nitro-3,5-dimethyl pyrazole, 4-bromo-3,5-dimethylpyrazole, and mixtures thereof.

Claim 5. The coating according to claim 1, wherein the blocking agent is selected from the group consisting of diethyl malonate, diisopropylamine, methylethyl ketoxime, 2- methoxypropoxypropanol, and combinations thereof.

Claim 6. The coating according to claim 1, wherein the blocking agent is a combination of diethyl malonate and diisopropylamine.

Claim 7. The coating according to claim 1, wherein the aliphatic polyurethane dispersion is an aliphatic, hydroxyftmctional polycarbonate ester-polyurethane dispersion.

Claim 8. A substrate having applied thereto the coating according to claim 1.

Claim 9. A process of producing a coating comprising: combining

(A) a waterborne polyurethane comprising

(Al) an aliphatic, hydrophobic polyisocyanate, and

(A2) an aliphatic polyurethane dispersion, wherein the aliphatic, hydrophobic polyisocyanate is blocked with a blocking agent; and

(B) curing the waterborne polyurethane to form a coating, wherein the coating is self-healing defined as having a gloss retention of at least 90% at 20° and 60° after scratching with steel wool and heating to 60°C for two hours, and wherein the coating has a similar final film hardness at a shorter drying time to a comparable waterborne polyurethane comprising an aliphatic, hydrophilic polyisocyanate and the same aliphatic polyurethane dispersion.

Claim 10. The process according to claim 9, wherein the aliphatic hydrophobic polyisocyanate is selected from the group consisting of di-cyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, hexamethylene diisocyanate, tetramethylxylene diisocyanate, and oligomeric hexamethylene diisocyanate.

Claim 11. The process according to claim 9, wherein the aliphatic hydrophobic polyisocyanate is hexamethylene diisocyanate.

Claim 12. The process according to claim 9, wherein the blocking agent is selected from the group consisting of phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, hydroxybenzoic acid, g-caprolactam, 5- valerolactam, y-butyrolactam, P-propiolactam, methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, methoxymethanol, benzyl alcohol; glycolic acid; methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylolurea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, formamide oxime, acetamide oxime, acetoxime, methylethyl ketoxime, diacetyl monoxime, benzophenone oxime, cyclohexane oxime, dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol, acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetamide, stearamide, benzamide, succinimide, phthalimide, maleimide, diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenylamine, imidazole, 2-ethyl imidazole, urea, thiourea, ethylene urea, ethylenetiourea, diphenylurea, N-phenyl carbamate phenyl, ethyleneimine, propyleneimine, sodium bisulfite, potassium bisulfite, 3,5-dimethylpyrazole, 3- methylpyrazole, 4-nitro-3,5-dimethyl pyrazole, 4-bromo-3,5-dimethylpyrazole, and mixtures thereof.

Claim 13. The process according to claim 9, wherein the blocking agent is selected from the group consisting of diethyl malonate, diisopropylamine, methylethyl ketoxime, 2- methoxypropoxypropanol, and combinations thereof.

Claim 14. The process according to claim 9, wherein the blocking agent is a combination of diethyl malonate and diisopropylamine.

Claim 15. The process according to claim 9, wherein the aliphatic polyurethane dispersion is an aliphatic, hydroxyfunctional polycarbonate ester-polyurethane dispersion.

Claim 16. A substrate having applied thereto a coating made according to claim 9.

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