Polyurethane multilayer protective films

Abstract

Multilayered films comprising a carrier, a thermoset clear coat, and a thermoplastic polyurethane layer, wherein amino groups on the surface of the thermoset clear coat are crosslinked with isocyanate groups on the surface of the thermoplastic polyurethane layer. A method of making the multilayered films including applying an aqueous polyurethane dispersion onto a carrier, curing the aqueous polyurethane dispersion to provide the thermoset clear coat, and applying a polyurethane composition to the thermoset clear coat to form the thermoplastic polyurethane layer. The multilayered films can be used, for example, as paint protective films for vehicles.

Description

POLYURETHANE MULTILAYER PROTECTIVE FILMS Background

[0001] Multilayer films are used to protect underlying substrates from damage caused by environmental weathering, stains and / or scratches. These films can be used to protect either painted or unpainted surfaces. When applied to a painted surface, they are commonly referred to as paint protection films.

[0002] Films made from polyurethane can withstand harsh environments, making them suitable for protection films. Polyurethanes are synthetic polymers commonly prepared by reacting a multifunctional isocyanate with a multifunctional diol or polyol in the presence of a catalyst to produce polymers containing carbamate (—NH—CO—O—) linkages. Thermoplastic polyurethanes are characterized by linear polymeric chains having self-ordering block structures, while thermoset polyurethanes are highly crosslinked by covalent bonds.

[0003] Depending on the components used to make the polyurethane, these films can be engineered to display a high degree of chemical resistance and a wide range of material properties. Polyurethanes can also be extremely durable and flexible, making them desirable materials for many applications. Summary

[0004] Some multilayered protective films include a bulk polyurethane layer having a solvent- based clear coat on one major surface and an adhesive on the opposite major surface. The clear coats are typically applied to the polyurethane layer and cured. However, the high curing temperatures (e.g., 295 °F or greater) can soften the polyurethane layer, which enables the migration of solvents and processing aids from the clear coat, such as wax and anti-sticking agents, into the urethane and adhesive layers. The resultant films can be left with a strong solvent odor and exhibit reduced peel adhesion to substrates.

[0005] The present disclosure provides multilayered films that demonstrate good chemical / stain resistance and mechanical performance. An aqueous polyurethane dispersion is applied to a carrier web, cured, and then laminated to a thermoplastic polymer layer by an extrusion or a hot lamination process. The aqueous polyurethane dispersion cures to form a thermoset clear coat with available surface amino groups that then react with available isocyanate groups in the polyurethane layer to improve adhesion between the clear coat and polyurethane layer. The resultant multilayered film demonstrates excellent stain resistance and mechanical stretchability. Further, the process used to produce the multilayered film can reduce strong odors, significantly improve throughput yield, and reduce factory cost.

[0006] The multilayered films disclosed herein can be commercially desirable for protecting, for example, the painted surface of various body parts of a vehicle such as, for example, an automobile,aircraft, watercraft, etc., especially those portions of the vehicle body (e.g., the leading edge of the front hood and other leading surfaces, rocker panels, etc.) that are exposed to such hazards as flying debris (e.g., sand, rocks, etc.), insects, or the like.

[0007] In one embodiment, the present disclosure provides a method of making a multilayered film, the method comprising: applying an aqueous polyurethane dispersion onto a carrier; curing the aqueous polyurethane dispersion to provide a thermoset clear coat having a first major surface opposite a second major surface, the second major surface adjacent the carrier; applying a polyurethane composition to the first major surface of the thermoset clear coat, the polyurethane composition forming a thermoplastic polyurethane layer, wherein the first major surface of the thermoset clear coat has available amino groups prior to application of the polyurethane composition, wherein the polyurethane composition has available isocyanate groups, and wherein the available amino groups of the thermoset clear coat react with the available isocyanate groups of the polyurethane composition.

[0008] In another embodiment, the present disclosure provides a multilayered film comprising: a carrier; a thermoset clear coat; and a thermoplastic polyurethane layer, wherein the thermoset clear coat is sandwiched between the carrier and the thermoplastic polyurethane layer, and wherein amino groups in the thermoset clear coat are crosslinked with isocyanate groups in the thermoplastic polyurethane layer.

[0009] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments. Brief Description of Drawings

[0010] FIG.1 is a cross-section view of one embodiment of a multilayered film of the present disclosure;

[0011] FIGS.2A and 2B are the stress-strain curves for Comparative Example 1 and Example 1, respectively;

[0012] FIGS.3A and 3B are the stress-strain curves for Comparative Example 2 and Example 2, respectively;

[0013] Unless otherwise indicated, all figures and drawings in this document are not to scale and are chosen for the purpose of illustrating different embodiments of the invention. In particular, the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the drawings, unless so indicated.Detailed Description

[0014] In the following description of illustrative embodiments, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

[0015] As used herein:

[0016] The term “comprises” and variations thereof do not have a limiting meaning where these terms appear in the description and claims. Such terms will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements. By “consisting of” is meant including, and limited to, whatever follows the phrase “consisting of.” Thus, the phrase “consisting of” indicates that the listed elements are required or mandatory, and that no other elements may be present. By “consisting essentially of” is meant including any elements listed after the phrase, and limited to other elements that do not interfere with or contribute to the activity or action specified in the disclosure for the listed elements. Thus, the phrase “consisting essentially of” indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present depending upon whether or not they materially affect the activity or action of the listed elements.

[0017] The terms “a,” “an,” and “the” are used interchangeably with “at least one” to mean one or more of the components being described.

[0018] The term “and / or” means one or all of the listed elements or a combination of any two or more of the listed elements.

[0019] The term “some embodiments” means that a particular feature, configuration, composition, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of such phrases in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

[0020] The terms “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances; however, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure.

[0021] All numbers are assumed to be modified by the term “about”. As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used.

[0022] The recitations of numerical ranges by endpoints include all numbers subsumed within that range as well as the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). The phrase “up to” a number (e.g., up to 50) includes the number (e.g., 50).

[0023] The term “hydroxyl component” means one or more polyols.

[0024] The term “isocyanate component” means one or more polyisocyanates.

[0025] The term “polyol” means a compound having a hydroxyl (OH) functionality of two or more.

[0026] The term “diol” means a compound having a hydroxyl functionality of two.

[0027] The term “diisocyanate” means a compound having an isocyanate (NCO) functionality of two.

[0028] “Polyisocyanate” means a compound having an isocyanate (NCO) functionality of two or more.

[0029] The term “cure” means to alter the physical state and or chemical state of the composition, to make it transform from a fluid to less fluid state, to go from a tacky to a non-tacky state, to go from a soluble to insoluble state, to decrease the amount of polymerizable material by its consumption in a chemical reaction, or go from a material with a specific molecular weight to a higher molecular weight.

[0030] The term “weight-average molecular weight” as used herein refers to Mw, which is equal to ΣMi2ni / ΣMini, where niis the number of molecules of molecular weight Mi. The weight-average molecular weight can be determined using light scattering, small angle neutron scattering, X-ray scattering, gel permeation chromatography, and sedimentation velocity.

[0031] FIG.1 is a cross-sectional view of a multilayered film of the present disclosure. The multilayered film 10 generally comprises a carrier 12, a thermoset clear coat 14, and a thermoplastic polyurethane layer 16, wherein the thermoset clear coat 14 is sandwiched between the carrier 12 and thermoplastic polyurethane layer 16. Surface amino groups in the thermoset clear coat 14 crosslink with surface isocyanate groups in the thermoplastic polyurethane layer 16 to provide good adherence. The multilayered film 10 may optionally include an adhesive 18 on a major surface 17 of the thermoplastic polyurethane layer 16. An optional protective release liner 22 may be applied to the adhesive layer 18. Each of the components of the multilayered film will be discussed in further detail below.

[0032] Thermoset Clear Coat

[0033] The thermoset clear coat is the cured product of an aqueous polyurethane dispersion comprising a polyurethane, a crosslinking agent and water. The thermoset clear coat of the present disclosure has on its surface available amino groups that react with available surface isocyanate groups in the thermoplastic polyurethane layer to enhance the bond between the two.

[0034] The polyurethane in the aqueous polyurethane dispersion is not particularly limiting and is the reaction product of a hydroxyl (OH) component and an isocyanate component (NCO). Thehydroxyl component comprises one or more polyols. The isocyanate component comprises one or more polyisocyanates. The term polyol as used herein includes, diols, triols, as well as other polyols useful in forming polyurethane materials. The hydroxyl component and the isocyanate component can be provided as two-part compositions with a hydroxyl component comprising one part and the isocyanate component comprising the second part.

[0035] Exemplary polyols include caprolactone polyols, polycarbonate polyols, polyester polyols, polyacrylic polyols, polyether polyols, polyolefin polyols, and combinations thereof. Typical equivalent weights of useful polyols are 28 to about 3000. However, other polyols having equivalent weights outside of the noted range may be suitable for use in the thermoset clear coat.

[0036] Suitable polyisocyanates include polyisocyanates with an isocyanate functionality of at least 2. In exemplary embodiments, the polyisocyanate is a primary polyisocyanate, such as a primary aliphatic polyisocyanate. Primary polyisocyanates having an isocyanate functionality of 3 or more can be made from primary diisocyanates, such as 1,6-hexamethylene diisocyanate, trimethyl- hexamethylene diisocyanate, 1,4-tetramethylene diisoycanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, 1,12-dodecamethylene diisocyanate, 2-methylpentamethylene diisocyanate, or 1,4- cyclohexane dimethylene diisocyanate.

[0037] In some embodiments, the thermoset clear coat comprises a polyurethane that is the reaction product of a composition comprising a polyester polyol and an aliphatic diisocyanate. Commercial sources of suitable polyurethanes include aliphatic polyurethane dispersions available under the trade designations Sancure 20898, Sancure 20041, and Sancure 2027 available from The Lubrizol Corporation in Wickliffe, OH and aliphatic polyurethane dispersions available under the trade designation NeoRez R-4000 from Covestro Coating Resing in B.V. Netherlands.

[0038] Suitable crosslinking agents for making the thermoset clear coat include polyfunctional aziridine crosslinkers. Polyfunctional aziridines can crosslink polymer chains within the thermoset clear coat through the isocyanate groups on neighboring polyurethane chains. Additionally, polyfunctional aziridines can hydrolyze in water with agitation to produce amines, some of which are available on the surface of the thermoset clear coat as amino groups. The available surface amino groups can react with available isocyanate groups on the surface of the thermoplastic polyurethane layer, thus providing greater interlayer adherence. In one embodiment, the crosslinking agent is aziridine. Sources of aziridine crosslinking agents include those available under the trade designations NEOCRYL CX-100 from DSM NeoResins Inc. in Wilmington, DE and PZ-28 from Polyaziridine LLC in Downingtown, PA.

[0039] The aqueous polyurethane dispersions used to make the clear coats of the present disclosure may comprise 95 wt.% to 99 wt.% polyurethane and 0.1 wt.% to 5 wt.% crosslinking agent based upon the total weight of solids in the dispersion. The term “solids”, as used herein in the context of percentage of solids in the aqueous polyurethane dispersion, means the components that remain in the clear coat after drying and curing. Solvents (e.g., water) driven off during formation ofthe clear coat are not considered solids. Since the solvent does not form part of the solids in the coating, the solids content will be approximately the same for the aqueous polyurethane dispersion and thermoset clear coat.

[0040] The aqueous polyurethane dispersions may further comprise at least one pH adjuster, a surfactant, a solvent, an ultraviolet absorber, a radical scavenger, a colorant, or a combination thereof.

[0041] Commercially available pH adjusters include aminomethyl propanol available under the trade designation AMP-95 from ANGUS in Buffalo Grove, IL.

[0042] The aqueous polyurethane dispersion can include any of a number of suitable surfactants, such as anionic surfactants. Anionic surfactants include, for example, sulfates such as sodium dodecyl sulfate, ammonium dodecyl sulfate, and sodium lauryl ether sulfate, and sulfosuccinnates such as dioctyl sodium sulfosuccinate and disodium lauryl sulfosuccinate. In aqueous coatings, these surfactants can be used in combination with co-dispersants. Co-dispersants include amino alcohols. Amino alcohols, such as 2-amino-2-methyl- 1-propanol, can assist in neutralizing acid-functional resins, making them suitable for use in aqueous dispersion. Commercially available surfactants include those under the trade designation Triton GR-7M from Dow Chemical Company in Midland, MI.

[0043] In addition to water, the aqueous polyurethane dispersion preferably includes a coalescing solvent. Suitable coalescing solvents include butyl carbitol and dipropylene glycol dimethyl ether, the latter of which is commercially available under the trade designation PROGLYDE DMM from Dow Chemical Company in Midland, MI.

[0044] The aqueous polyurethane dispersion can include ultraviolet absorbers which improve the weather resistance. Ultraviolet absorbers generally recognized in the art may be suitable for use with the invention. Commercially available ultraviolet absorbers include those under the trade designation TINUVIN 405, TINUVIN 571, and TINUVIN 1130 from BASF in Florham Park, NJ. The amount of ultraviolet absorber is typically 0.1 wt.% to 5 wt.% of solids in the aqueous polyurethane dispersion.

[0045] Alternatively, a hindered amine radical scavenger can be included or combined with an ultraviolet absorber. The hindered amine free radical scavengers generally recognized in the art contribute to photostabilization of the polyurethane by trapping alkoxy and hydroxy radicals produced by light-induced dissociation of hydroperoxides. Commercially available hindered amine free radical scavengers include those under the trade designation TINUVIN 292 from BASF. The amount of hindered amine radical scavenger is typically 0.1 wt.% to 5 wt.% of solids in the aqueous polyurethane dispersion.

[0046] Colorants and decorative solids can be added to the aqueous polyurethane dispersion to enhance the aesthetics of the multilayered film. Decorative solids could include such items as metal flakes, polymeric flakes, glitter, beads, or other materials that provide a decorative feature to the finished article. Colorants, such as pigments or dyes, and decorative solids are included at variouslevels to obtain a desired effect in the finished article. The amount of colorant and / or decorative solids is typically 0.1 wt.% to 30 wt.% of solids in the aqueous polyurethane dispersion.

[0047] The aqueous polyurethane dispersion is coated onto a carrier and cured to form the thermoset clear coat. The thickness of the thermoset clear coat is typically 5-50 μm, more particularly 5-30 μm. In some embodiments, the thickness of the thermoset clear coat is at least 5, 10, 15, 20, 25, 30, 35, or 40 μm. In some embodiments, the thickness of the thermoset clear coat is no greater than 50, 45, 40, 35, 30, 25, 20, 15, or 10 μm.

[0048] Thermoplastic Polyurethane

[0049] The thermoplastic polyurethane layer is the reaction product of a polyurethane composition that includes a diisocyanate, a polyester polyol having a melting temperature of at least about 30° C, and a chain extender.

[0050] Exemplary diisocyanates include those according to Formula I:In Formula 1, R is chosen from substituted or unsubstituted (C1-C40)alkylene, (C2-C40)alkenylene, (C4- C20)arylene, (C4-C20)arylene-(C1-C40)alkylene-(C4-C20)arylene, (C4-C20)cycloalkylene, and (C4- C20)aralkylene.

[0051] Other exemplary diisocyanates include dicyclohexylmethane-4,4′-diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, 1,3-phenylene diisocyanate, m-xylylene diisocyanate, tolylene-2,4-diisocyanate, toluene 2,4-diisocyanate, tolylene- 2,6-diisocyanate, poly(hexamethylene diisocyanate), 1,4-cyclohexylene diisocyanate, 4-chloro-6- methyl-1,3-phenylene diisocyanate, hexamethylene diisocyanate, toluylene diisocyanate, diphenylmethane 4,4′-diisocyanate, 1,4-diisocyanatobutane, 1,8-diisocyanatooctane, 2,6-toluene diisocyanate, 2,5-toluene diisocyanate, 2,4-toluene diisocyanate, m-phenylene diisocyanate, p- phenylene diisocyanate, methylene bis(o-chlorophenyl diisocyanate, methylenediphenylene-4,4′- diisocyanate, (4,4′-diisocyanato-3,3′,5,5′-tetraethyl) diphenylmethane, 4,4′-diisocyanato-3,3′- dimethoxybiphenyl (o-dianisidine diisocyanate), 5-chloro-2,4-toluene diisocyanate, 1-chloromethyl- 2,4-diisocyanato benzene, tetramethyl-m-xylylene diisocyanate, 1,6-diisocyanatohexane 1,12- diisocyanatododecane, 2-methyl-1,5-diisocyanatopentane, methylenedicyclohexylene-4,4′- diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 2,2,4-trimethylhexyl diisocyanate, or combinations thereof.

[0052] Suitable commercially available diisocyanates include the liquid cycloliphatic diisocyanate obtained under the trade designation DESMODUR W from Covestro in Leverkusen, Germany.

[0053] The amount of diisocyanate in the polyurethane composition can range from 0.5 to 50 wt.%. In some embodiments, the diisocyanate is at least 0.5, 5, 10, 15, 20, 25, 30, 35, or 40 wt.% of the polyurethane composition. In some embodiments, the diisocyanate is no greater than 50, 45, 40, 35, 30, 25, 20, 15, or 10 wt.% of the polyurethane composition.

[0054] The amount of the diisocyanate in the polyurethane composition can further be expressed in terms of an isocyanate index. An isocyanate index refers to the ratio of the equivalent amount of isocyanate functional groups used relative to the theoretical equivalent amount of hydroxy functional groups. The theoretical equivalent amount is equal to one equivalent isocyanate functional group per one equivalent hydroxyl group; this is an index ratio of 1.0. According to various embodiments, the polyurethane composition has an isocyanate index (i.e., NCO / OH ratio) ranging from 0.75 to 1.25, more particularly 0.95 to 1.05. In some embodiments, the polyurethane composition comprises an isocyanate index of at least 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, or 1.10. In some embodiments, the polyurethane composition comprises an isocyanate index of no greater than 1.25, 1.20, 1.15, 1.10, 1.05, 1.00, 0.95, 0.90, 0.85, or 0.80.

[0055] The polyester polyol in the polyurethane composition can include any suitable number of hydroxyl groups. For example, the polyester polyol can include four hydroxyl groups or three hydroxyl groups. The polyester polyol can even include two hydroxyl groups such that the polyester polyol is a polyester diol. In general, the polyester polyol can be a product of a condensation reaction such as a polycondensation reaction.

[0056] In examples where the polyester polyol is made according to a condensation reaction, the reaction can be between one or more carboxylic acids and one or more polyols. An example of a suitable carboxylic acid includes a carboxylic acid according to Formula II:In Formula II, R1is chosen from substituted or unsubstituted (C1-C40)alkylene, (C2-C40)alkylene, (C2- C40)alkenylene, (C4-C20)arylene, (C4-C20)cycloalkylene, and (C4-C20) aralkylene. Specific examples of suitable carboxylic acids include glycolic acid (2-hydroxyethanoic acid), lactic acid (2- hydroxypropanoic acid), succinic acid (butanedioic acid), 3-hydoxybutanoic acid, 3-hydroxypentanoic acid, terepthalic acid (benzene-1,4-dicarboxylic acid), naphthalene dicarboxylic acid, 4- hydroxybenzoic acid, 6-hydroxynaphtalane-2-carboxylic acid, oxalic acid, malonic acid (propanedioic acid), adipic acid (hexanedioic acid), pimelic acid (heptanedioic acid), ethonic acid, suberic acid (octanedioic acid), azelaic acid (nonanedioic acid), sebacic acid (decanedioic acid), glutaric acid (pentanedioic acid), dedecandioic acid, brassylic acid, thapsic acid, maleic acid ((2Z)-but-2-enedioicacid), fumaric acid ((2E)-but-2-enedioic acid), glutaconic acid (pent-2-enedioic acid), 2-decenedioic acid, traumatic acid ((2E)-dodec-2-enedioic acid), muconic acid ((2E,4E)-hexa-2,4-dienedioic acid), glutinic acid, citraconic acid ((2Z)-2-methylbut-2-enedioic acid), mesaconic acid ((2E)-2-methyl-2- butenedioic acid), itaconic acid (2-methylidenebutanedioic acid), malic acid (2-hydroxybutanedioic acid), aspartic acid (2-aminobutanedioic acid), glutamic acid (2-aminopentanedioic acid), tartonic acid, tartaric acid (2,3-dihydroxybutanedioic acid), diaminopimelic acid ((2R,6S)-2,6- diaminoheptanedioic acid), saccharic acid ((2S,3S,4S,5R)-2,3,4,5-tetrahydroxyhexanedioic acid), mexooxalic acid, oxaloacetic acid (oxobutanedioic acid), acetonedicarboxylic acid (3-oxopentanedioic acid), arbinaric acid, phthalic acid (benzene-1,2-dicarboxylic acid), isophtalic acid, diphenic acid, 2,6- naphtalenedicarboxylic acid, or a combination thereof.

[0057] An example of a suitable polyol includes a polyol according to Formula III:In Formula III, R2is chosen from substituted or unsubstituted (C1-C40)alkylene, (C2-C40)alkenylene, (C4-C20)arylene, (C1-C40)acylene, (C4-C20)cycloalkylene, (C4-C20)aralkylene, and (C1-C40)alkoxyene, and R3and R4are independently chosen from —H, —OH, substituted or unsubstituted (C1-C40)alkyl, (C2-C40)alkenyl, (C4-C20)aryl, (C1-C20)acyl, (C4-C20)cycloalkyl, (C4-C20)aralkyl, and (C1-C40)alkoxy.

[0058] An example of another suitable polyol includes a polyol according to Formula IV:In Formula IV, R5and R6are independently chosen from substituted or unsubstituted (C1-C40)alkylene, (C2-C40)alkenylene, (C4-C20)arylene, (C1-C40)acylene, (C4-C20)cycloalkylene, (C4-C20)aralkylene, and (C1-C40)alkoxyene and n is a positive integer greater than or equal to 1.

[0059] An example of yet another suitable polyol includes a polyol according to Formula V:In Formula V, R7is chosen from substituted or unsubstituted (C1-C40)alkylene, (C2-C40)alkenylene, (C4-C20)arylene, (C1-C40)acylene, (C4-C20)cycloalkylene, (C4-C20)aralkylene, and (C1-C40)alkoxyene and n is a positive integer greater than or equal to 1. In specific examples, the polyester polyol includes one or more of polyglycolic acid (poly[oxy(1-oxo-1,2-ethanediyl)]), polybutylene succinate (poly(tetramethylene succinate)), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), polyethylene terephthalate (poly(ethyl benzene-1,4-dicarboxylate)), polybutylene terephthalate (poly(oxy-1,4- butanediyloxycarbonyl-1,4-phenylenecarbonyl)), polytrimethylene terephthalate (poly(trimethylene terephthalate); poly(oxy-1,3-propanediyloxycarbonyl-1,4-phenylenecarbonyl)), polyethylene naphthalate (poly(ethylene 2,6-naphthalate)), poly(1,4-butylene adipate), poly(1,6-hexamethylene adipate), poly(ethylene-adipate), mixtures thereof, and copolymers thereof.

[0060] Suitable commercially available polyester polyols are available under the trade designation FOMREZ 44-111 from Chemtura, Philadelphia, PA.

[0061] In some embodiments, the polyester polyol has a melting temperature of at least 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, or 500º C. Choosing an appropriate melting temperature can help to increase the degree of crystallinity of the thermoplastic polyurethane layer. The degree of crystallinity can be determined through differential scanning calorimetry and is expressed as the fractional amount of crystallinity in the thermoplastic polyurethane film. The degree of crystallinity can be in a range of from 30-70%, more particularly 40-60%. The higher degree of crystallinity reduces the tackiness of the thermoplastic polyurethane layer making it easier to handle under ambient conditions (e.g., 25° C. and 1 ATM).

[0062] The amount of polyester polyol in the polyurethane composition can range from 40 – 70 wt.%, more particularly 50-60 wt.%. In some embodiments, the polyurethane composition comprises at least 40, 45, 50, 55, or 60 wt.% polyester polyol. In some embodiments, the polyurethane composition comprises no greater than 70, 65, 60, 55, or 50 wt.% polyester polyol.

[0063] The thermoplastic polyurethane composition also comprises a chain extender. Chain extenders can be used to strengthen the thermoplastic polyurethane layer. In some embodiments, the chain extender is a diol chain extender. Suitable diol chain extenders typically have a weight-average molecular weight from 30- 250 daltons, more particularly 50-150 daltons. In some embodiments, the weight-average molecular weight of the diol chain extender is at least 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 daltons. In some embodiments, the weight- average molecular weight of the diol chain extender is not greater than 250, 240, 230, 220, 210, 200, 190, 180, 170, 160, 150, 140, 130, 120, 110 or 100 daltons.

[0064] The diol chain extender can include any suitable number of carbons. For example, the diol chain extender can include 2-20 carbons, more particularly 3-10 carbons. In some embodiments, the diol chain extender has at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19carbons. In some embodiments, the diol chain extender has no greater than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, or 3 carbons. Examples of suitable diol chain extenders include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, or a mixture thereof. In some embodiments, the polyurethane composition comprises an aliphatic diisocyanate, a polyester polyol having a melt temperature of at least 30° C, and 1,4-butandiol as a chain extender.

[0065] The polyurethane composition typically comprises 1-15 wt.%, more particularly 1-10 wt.% of the diol chain extender. In some embodiments, the polyurethane composition comprises at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 wt.% diol chain extender. In some embodiments, the polyurethane composition comprises no greater than 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, or 2 wt.% diol chain extender.

[0066] The thermoplastic polyurethane can include a hard segment. A hard segment generally refers to harder, less flexible polymer segment, which results from polymerization of the diisocyanate and the diol chain extender. The amount of the hard segment can be determined by calculating the total amount (wt.%) of isocyanate, chain extender, and cross-linker. That total amount is then divided by the total weight of the thermoplastic polyurethane. The hard segment can be in a range of from 35- 65 wt.% of the thermoplastic polyurethane film. In some embodiments, the polyurethane composition has a hard segment content of at least 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 wt.% of the thermoplastic polyurethane film. In some embodiments, the thermoplastic polyurethane film has a hard segment content of no greater than 65, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, or 40 wt.%. Hard segments are present as domains, which can interact with each other to effectively form a crosslink therebetween (e.g., through a hydrogen bond). Under stress for example, through a mechanical deformation, the hard segments can become aligned in the stress direction. This alignment coupled with the hydrogen bonding can contribute to the stiffness, elastomeric resilience, or tear resistance of the thermoplastic polymeric film.

[0067] The polyurethane compositions may further comprise a catalyst, an ultraviolet absorber, a radical scavenger, a colorant, an antioxidant, or a combination thereof.

[0068] Useful catalysts in the polymerization of polyurethanes include aluminum-, bismuth-, tin-, vanadium-, zinc-, mercury-, and zirconium-based catalysts, amine catalysts, and mixtures thereof. Preferred catalysts include tin based catalysts, such as dibutyl tin compounds. Especially preferred are catalysts selected from the group consisting of dibutyltin diacetate, dibutyltin dilaurate, dibutyltin diacetyl acetonate, dibutyltin dimercaptide, dibutyltin dictate, dibutyltin dimaleate, dibutyltin acetylacetonate, and dibutyltin oxide. Commercially available dibutyl tin dilaurate catalysts include those obtained under the trade designation DABCO T12 CATALYST from Air Product in Allentown, PA. Suitable amounts of the catalyst can be from 0.0001 wt.% to 0.2 wt.%, more particularly from0.0001 wt.% to 0.15 wt.%, and even more particularly from 0.0001 wt.% to 0.1 wt.% based on the overall weight of the polyurethane composition.

[0069] Suitable ultraviolet absorbers, radical scavengers and colorant include those cited above with respect to the thermoset clear coat.

[0070] Exemplary antioxidants include a steric hindered phenolic resin available under the trade designations Irganox 1076, Irganox 1010 and Irganox 1035 from BASF.

[0071] The thermoplastic polyurethane layer can have a weight-average molecular weight in a range of from 80,000-400,000 daltons, more particularly 80,000-200,000 daltons. The high molecular weight of the thermoplastic polyurethane layer can help to prevent discoloration of the layer. This is because the relatively high molecular weight of the thermoplastic polyurethane layer can result from long chain length polyurethanes. The long chain length can form relatively tightly packed or highly entangled polymers such that a discoloring compound cannot readily penetrate the thermoplastic polyurethane layer and cause discoloration therein.

[0072] The polyurethane composition is applied to the thermoset clear coat and cured to produce the thermoplastic polyurethane layer. The thickness of the thermoplastic polyurethane layer typically ranges from 1 mils to 20 mils, more particularly 2 to 12 mils. In some embodiments, the thickness of the thermoplastic polyurethane layer is at least 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5, 16.0, 16.5, 17.0, 17.5, or 18.0 mils. In some embodiments, the thickness of the thermoplastic polyurethane layer is no greater than 20.0, 19.5, 19.0, 18.5, 18.0, 17.5, 17.0, 16.5, 16.0, 15.5, 15.0, 14.5, 14.0, 13.5, 13.0, 12.5, 12.0, 11.5, 11.0, 10.5, 10.0, 9.5, 9.0, 8.5, 8.0, 7.5, 7.0, 6.5, 6.0, 5.5, 5.0, 4.5, 4.0, 3.5, or 3.0 mils.

[0073] Adhesive

[0074] Optionally, an adhesive 18 may be applied on a first major surface 17 of the thermoplastic polyurethane layer 16 that is opposite to a second major surface 19 adjacent to the first major surface 13 of the thermoset clear coat 14, as illustrated in FIG.1. The adhesive layer can be a pressure sensitive adhesive and is normally tacky at ambient conditions. Suitable pressure sensitive adhesives can be based on polyacrylates, synthetic and natural rubbers, polybutadiene and copolymers or polyisoprenes and copolymers. Silicone based adhesives such as polydimethylsiloxane and polymethylphenylsiloxane may also be used.

[0075] Particularly preferred pressure sensitive adhesives include polyacrylate-based adhesives, which can display advantageous properties as high degrees of clarity, UV-stability and aging resistance. Polyacrylate adhesives that can be used in surfacing film applications are described, for example, in U.S. Pat. No.4,418,120 (Kealy et al.); Pat. No. RE24,906 (Ulrich); U.S. Pat. No. 4,619,867 (Charbonneau et al.); U.S. Pat. No.4,835,217 (Haskett et al.); and International Publication No. WO 87 / 00189 (Bonk et al.).

[0076] Preferably, the polyacrylate pressure sensitive adhesive comprises a crosslinkable copolymer of a C4-C12 alkyl acrylate and an acrylic acid. The adhesive can be used with or without a crosslinker. Useful crosslinking reactions include chemical crosslinking and ionic crosslinking. The chemical crosslinker could include polyaziridine and / or bisamide and the ionic crosslinker may include metal ions of aluminum, zinc, zirconium, or a mixture thereof. A mixture of chemical crosslinker and ionic crosslinker can also be used. In some embodiments, the polyacrylate pressure sensitive adhesive includes a tackifier such as rosin ester. Adhesives useful in the invention may also contain additives such as ground glass, titanium dioxide, silica, glass beads, waxes, tackifiers, low molecular weight thermoplastics, oligomeric species, plasticizers, pigments, metallic flakes and metallic powders as long as they are provided in an amount that does not unduly degrade the quality of the adhesive bond to the surface.

[0077] As an alternative to pressure sensitive adhesives, the adhesive layer may be a hot melt adhesive, which is not tacky at room temperature but becomes tacky upon heating. Such adhesives include acrylics, ethylene vinyl acetate, and polyurethane materials.

[0078] In some embodiments, the adhesive covers the entire first major surface 17 of the thermoplastic polymer layer 16. In other embodiments, the adhesive is pattern coated onto the first major surface 17 of the thermoplastic polymer layer 16 (i.e., the first surface has regions with and without adhesive). The pattern of coated and uncoated areas can be uniform or random. The thickness of the adhesive is not particularly limiting. In some embodiments, the thickness of the adhesive is 15- 60 micrometers, more particularly from 15-50 micrometers, and even more particularly from 15 micrometers to 45 micrometers.

[0079] For certain applications, such as applying the surfacing film to an automotive exterior, it may be desirable for the adhesive to be repositionable, at least initially, so that the sheet can be adjusted to fit at a desired place before a permanent bond is formed. Such repositionability may be achieved by providing, for example, a layer of minute glass bubbles on the adhesive surface as disclosed in U.S. Pat. No.3,331,729 (Danielson et al.).

[0080] In some embodiments, a release liner 22 may be applied to the adhesive 18 to protect the adhesive prior to use of the multilayered film. The composition of the release liner will depend upon the chemistry of the adhesive (i.e., the release liner must adhere to the adhesive during transport but release prior to application of the multilayered film to a substrate). In some embodiments, the release liners include paper, e.g., kraft paper, or polymeric films, e.g., polyethylene, polypropylene or polyester. At least one surface of the liner can be treated with a release agent such as silicone, a fluorochemical, or other low surface energy based release material.

[0081] Method

[0082] The multilayered films 10 of the present disclosure can be made by applying the aqueous polyurethane dispersion disclosed herein onto a carrier 22 and curing the aqueous polyurethane dispersion to provide a thermoset clear coat 14 having a first major surface 13 and a second majorsurface 15, as illustrated in FIG.1. The aqueous polyurethane dispersion may be applied to the carrier using conventional coaters, including knife coaters, roll coaters, reverse roll coaters, notched bar coaters, curtain coaters, rotogravure coaters, and rotary printers. The viscosity of the aqueous polyurethane dispersion can be adjusted (e.g., adding water) according to the type of coater used. In some embodiments, the viscosity of the aqueous polyurethane dispersion ranges from 70 cps to 180 cps.

[0083] The carriers are made from materials that are releasable from the thermoset clear coat. Exemplary carriers include polyester, polypropylene, high density polyethylene, polymer coated papers, or combinations thereof. Additional exemplary carriers include biaxially oriented polyester and papers that may be coated or printed with a composition. Such coatings include those formed from polyacrylates, silicone, and fluorochemicals.

[0084] The coated aqueous polyurethane dispersion is then dried and cured at elevated temperatures. An increasing temperature profile is preferably used to first evaporate the solvent and then cure the composition to form the thermoset clear coat. An exemplary temperature profile for an aqueous polyurethane dispersion coating of 50 μm thick is 1 minute at each of 121º C, 149º C, and 163º C. The temperature and time should be sufficient to cure the aqueous polyurethane dispersion to a film while leaving available amino groups at the surface for bonding with the isocyanate groups in the thermoplastic polyurethane layer.

[0085] The thermoplastic polyurethane layer 16 is formed on the thermoset clear coat by a hot lamination process using an extruder and cold roller. Examples of suitable extruders include a twin- screw extruder (e.g., co-rotating-twin-screw extruder or a counter-rotating-twin-screw extruder) and a planetary extruder.

[0086] A thermoplastic polyurethane can be introduced into the extruder in pellet form. Preferably, however, the components of the polyurethane composition (e.g., the diisocyanate, polyester polyol, chain extender, etc.) can be individually or simultaneously fed into the extruder. This provides for a reaction mixture that is free of any components necessary for pelletization such as wax processing aids, or an antisticking agent. Further, this pellet free method provides for thermoplastic polyurethanes having higher weight-average molecular weights (e.g., at least 80,000 daltons). This is because pellets introduced into an extruder can be subjected to significant shear, which can shorten the thermoplastic polyurethane chains and thus reduce the weight-average molecular weight of the resulting thermoplastic polyurethane film. Higher molecular weight polyurethanes can make it more difficult for discoloring agents to penetrate the polyurethane film.

[0087] In either case, molten thermoplastic polyurethane is formed and extruded through a die onto the thermoset clear coat 14 to produce the thermoplastic polyurethane layer 16. An example of a suitable die includes a coat hanger die. The extruded polyurethane layer can be further pressed by a cold roller which solidifies the thermoplastic polyurethane to obtain the thermoplastic polyurethane layer. The extrusion can occur at any suitable temperature. For example, the temperature can be in arange of from 40-230° C, more particularly 90- 200° C. The extrusion can occur for any suitable amount of time. For example, the extrusion can occur for a period of time ranging from 0.5-17 hours, more particularly 1-6 hours. The first major surface of the thermoset clear coat has available amino groups prior to application of the polyurethane composition. The polyurethane composition has available isocyanate groups. The available amino groups of the thermoset clear coat react with the available isocyanate groups of the polyurethane composition to provide good adherence between the thermoset clear coat and the thermoplastic polyurethane layer.

[0088] An adhesive 18 may optionally be applied to the first major surface 17 of the thermoplastic layer 16. In some embodiments, the first major surface 17 of the thermoplastic polyurethane layer may be pretreated prior to application of the adhesive. Such pretreatment may include corona discharge, plasma discharge, flame treatment, electron beam irradiation, ultraviolet (UV) radiation, acid etching, chemical priming and combinations thereof. Application of the adhesive can be directly onto the thermoplastic layer. More preferably, the adhesive is coated onto a release liner and the adhesive then applied to the thermoplastic layer by thermal lamination. Adhesive may be coated onto the thermoplastic layer or release liner using conventional techniques, including solvent coating methods, water-borne coating methods, or hot melt coating methods, e.g., knife coating, roll coating, reverse roll coating, gravure coating, wire wound rod coating, slot orifice coating, slot die coating, extrusion coating, or the like.

[0089] Additionally, a release liner 22 may be laminated to the adhesive to protect the adhesive prior to use of the multilayered film.

[0090] Properties of Multilayered Film

[0091] The multilayer films disclosed herein are typically transparent, and possibly even translucent, for paint protection applications. The multilayer film may also be transparent, translucent or even opaque for other surface protection or enhancement applications. For some applications, it may be desirable for the present multilayer film to be colored. The present film could be colored such as, for example, by one or more of its layers further comprising a coloring agent, as described above.

[0092] In some embodiments, the multilayered film is conformable. The conformability of the film may be characterized by tensile testing, as determined by the Tensile Strength and Elongation at Break Test Method described in the Examples.

[0093] Conformable films generally have a lower ultimate tensile strength in comparison to polyester (PET). For example, PET has an ultimate tensile strength of at least 150 MPa; while conformable films typically have an ultimate tensile strength less than 100 MPa. In some embodiments, the multilayered films disclosed herein have an ultimate tensile strength of at least 10, 12, or 14 MPa. In some embodiments, the multilayered films have an ultimate tensile strength less than 100, 90, 80, 70, 60, 50 or 40 MPa. In some embodiments, the multilayered films have an ultimate tensile strength from 10 to 99 MPa, 10 to 80 MPa, 10 to 60 MPa, or even 10 to 40 MPa.

[0094] Conformable films generally have a higher tensile strain at break, or in other words a higher elongation at break in comparison to polyester (PET). For example, PET has a tensile strain at break of less than 100%, while conformable films typically have a tensile strain at break of at least 150, 175, or 200%. In some embodiments, the multilayered films have a tensile strain at break of at least 200%, 300%, 400%, 500%, or 600%. In some embodiments, the multilayered films have a tensile strain at break from 200 to 700%.

[0095] The multilayered films of the present disclosure are typically chemical and stain resistant. In some embodiments, the multilayered films exhibit a ΔE and Δb that are each no greater than 3 when subject to the Stain Test Method disclosed herein.

[0096] Applications

[0097] The multilayered films disclosed herein can be applied to many suitable substrates. Moreover, the multilayered film can be cut to precisely match the dimensions of any desired substrate. The substrate, as an example, can be a vehicle body, a window, or a portion thereof. With respect to a car, for example, the multilayered film can be sized to precisely fit a portion of a hood for a specific make and model of an automobile. In addition to a hood, the multilayered film can be cut to conform to other features of an automobile such as a fender, a mirror, a door, a roof, a panel, a portion thereof.

[0098] The multilayered film can also be sized to precisely fit a portion of a water vessel such as a hull (e.g., to protect the hull during beaching), a transom (e.g., to protect the transom from damage caused by water skis), or a bulwark (e.g., to prevent damage caused by lines). Additionally, the multilayered film can be applied to trains or even aerospace vehicles such as an airplane or helicopter. For example, the multilayered film can be applied to a blade such as a propeller blade (e.g., to protect against debris strikes such as ice), an airfoil (e.g., a wing or a helicopter blade), or a fuselage. Examples

[0099] Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims.Table 1. Materials Designation Description Source Sancure 20898 A waterborne aliphatic polyurethane The Lubrizol dispersion available under the trade Corporation, Wickliffe, designation “Sancure 20898”. OH Turboset 2027 A waterborne aliphatic polyurethane The Lubrizol dispersion available under the trade Corporation, Wickliffe, designation “Turboset 2027”. OH Sancure 20041 A waterborne aliphatic polyurethane The Lubrizol dispersion available under the trade Corporation, Wickliffe, designation “Sancure 20041”. OH AMP-95 A multifunctional amino alcohol under the ANGUS®, Buffalo trade designation “AMP-95”. Grove, IL Triton GR-7M A sulfosuccinate type anionic surfactant Dow Chemical under the trade designation “TRITON GR- Company, Midland, MI 7M”. DMM A dipropylene glycol dimethyl ether under Dow Chemical the trade designation “PROGLYDE DMM”. Company, Midland, MI CX-100 An aziridine crosslinker under the trade DSM NeoResins Inc., designation “NEOCRYL CX-100”. Wilmington, MA T-1130 A liquid UV absorber of the hydroxyphenyl BASF, Florham Park, benzotriazole class under the trade NJ designation “TINUVIN 1130”. T-405 A solid triazine-based UV absorber for BASF, Florham Park, coatings under the trade designation NJ “TINUVIN 405”. F44-111 A polyester polyol, molecular weight = 1000 Chemtura, Philadelphia, g / mol, under the trade designation PA “FOMREZ 44-111” 1,4-butanediol A chain extender diol, 99.8% pure BASF, Ludwigshafen, Germany T292 A liquid hindered amine light stabilizer BASF, Florham Park, under the trade designation “TINUVIN NJ 292”. T571 A UV light absorber of the hydroxyphenyl BASF, Florham Park, benzotriazole class obtained under the trade NJ designation “TINUVIN 571”. DT12 Dibutyl tin dilaurate catalyst under the trade Air Products, designation “DABCO T12 CATALYST”. Allentown, PA DES-W Liquid cycloaliphatic diisocyanate under the Covestro, Leverkusen, trade designation “DESMODUR W”. Germany Butyl carbitol Diethylene glycol monobutyl ether TCI America I1076 Antioxidant under the trade designation BASF, Florham Park, “Irganox 1076”. NJ Polyester carrier web Polyethylene terephthalate film under trade Mitsubishi designation HOSTAPHAN polyester films.

[0100] Tensile Strength and Elongation at Break Test Method

[0101] The tensile properties of the hard coat layer were evaluated using the procedures described in ASTM Test Method D 882-02 (2002), "Tensile Properties of Thin Plastic Sheeting" using an INSTRON tensile tester (Instron, Norwood, MA). Percent elongation at break was measured at room temperature. Young’s Modulus was also measured from the initial linear portion of the stress-strain curve. Specimens were 2.54 centimeters (cm) in width and 1.27 cm in length. Each specimen was tested at a crosshead speed of 30.5 cm / minute with a 1.27 cm jaw separation. Typically, 3 specimens were run for each sample.

[0102] Staining Test Method

[0103] A colorimeter (Color i5 from X-rite, Grand Rapids, MI) was positioned in front of the clear coat side of each sample and the color was measured using the CIELAB color space according to ASTM E1347 (2020) under a 25 mm orifice. A 50% by volume mixture of Marathon Oil AC-20 non-emulsified asphalt cement (Marathon, Houston, TX) was prepared in unleaded gasoline to make a test fluid. Each of the samples were dipped into the test fluid for 10 seconds. The samples were then suspended in a ventilated hood test chamber for 15 minutes allowing the solution to drain / evaporate. After 15 minutes, the samples were cleaned thoroughly with naphtha and then the color was remeasured as described above. The total color change (ΔE) and yellow color change (Δb) were calculated.

[0104] Clear Coat Preparative Sample 1 (PREP 1)

[0105] An aqueous polyurethane dispersion was prepared by mixing 83.78 grams of Sancure 20898, 0.03 grams of a pH adjuster AMP-95, 0.19 grams of Triton GR-7M, 8.47 grams of butyl carbitol, 1.08 grams of T405, and 0.45 grams of T292. The dispersion was diluted with de-ionized water to maintain the viscosity between 70 cps and 180 cps. Just prior to coating, 1.75 wt.% of crosslinker CX-100 based total weight of aqueous polyurethane dispersion were added under agitation.

[0106] Clear Coat Preparative Samples 2-3 (PREPS 2-3)

[0107] PREPS 2 to 3 were made from Turboset 2027 and Sancure 20041, respectively, using the same method as described for PREP 1.

[0108] Clear Coat Preparative Sample 4 (PREP 4)

[0109] An aqueous polyurethane dispersion was prepared by mixing 83.78 grams of a waterborne polyurethane dispersion Sancure 20898, 0.03 grams of a pH adjuster AMP-95, 0.19 grams of Triton GR-7M, 8.35 grams of DMM, 1.20 grams of T405, and 0.45 grams of T292. The dispersion was diluted with de-ionized water to maintain the viscosity between 70 cps and 180 cps. Just prior tocoating, 1.75% of crosslinker CX-100 based total weight of aqueous polyurethane dispersion were added under agitation.

[0110] Example 1 (EX 1)

[0111] The PREP 1 formulation was coated onto a polyester carrier web to a thickness of about 50 microns. The coated dispersion was dried and cured sequentially in separate ovens for about 1.0 minutes each. The oven temperatures were set at 121° C, 149 °C, and 163° C, for the first, second, and third ovens, respectively. The resulting clear film (about 11-12 microns thick) on the polyester carrier web was then used for lamination with the reactive extruded thermoplastic polyurethane (TPU) bulk layer.

[0112] The TPU layer was prepared as follows: All the ingredients including 505.2 grams of pre- melted F44-111 (having a melting temperature of 60 °C) at 100 °C, 5 grams of I1076, 0.3 grams of T12, 85.7 grams of 1,4-butanediol 397.2 grams of DES W, 3 grams of T-292, and 4.5 grams of DT- 571 were fed separately into a twin screw extruder. The extruder setup, conditions, and temperature profiles were similar to that described in Example No.1 and in Table 1 in U.S. Pat. No.8,551,285. The isocyanate index was NCO / OH=l.04 and hard segment content was 48.25%. The resulting aliphatic thermoplastic polyurethane film (TPF) was extruded as a 100 micrometers thick layer onto the top surface of the PREP 1 layer and then laminated between the nip of a backup roll against a chill roll. The resulting laminated film was aged 2 weeks at ambient temperature.

[0113] Examples 2-4 (EX 2-4)

[0114] Examples 2-4 were prepared with the same method as EX 1, but with PREPS 2-4 formulations, respectively.

[0115] Comparative Example 1 (CE 1)

[0116] The PREP 1 formulation was coated to a thickness of about 50 microns onto an extruded TPU bulk layer of 100 micrometers thickness having the same composition as described in EX 1. The coated formulation was dried and cured sequentially in separate ovens for about 1.0 minutes each. The oven temperatures were set at 121° C, 149 °C, and 163° C, for the first, second, and third ovens, respectively. The resulting clear film on TPF was about 11-12 microns thick.

[0117] Comparative Examples 2-4 (CES 2-4)

[0118] CES 2 to 4 were prepared by coating PREP 2 to 4 formulations, respectively, onto an extruded TPU layer and dried, as described for CE 1. The resulting clear film layer on TPU was about 11-12 microns thick.

[0119] Analysis

[0120] The tensile and elongation at break for EXS 1-4 and CES 1-3 were determined using the Tensile Strength and Elongation at Break Test Method. The stress-strain curves for CE 1 and EX 1 are provided in FIGS.2A and 2B, respectively. The stress-strain curves for CE2 and EX 2 are provided in FIGS.3A and 3B, respectively The numerical results are provide in Table 2.

[0121] Table 2. Tensile Strength and Elongation at Break Samples Tensile Strength (MPa) Elongation at break (%) CE-1 29.64 610 EX-1 17.4 332 CE-2 28.73 580 EX-2 14.96 282 CE-3 38.58 697 EX-3 20.8 376 CE-4 TBD TBD EX-4 30 303

[0122] The stain resistance of EXS 1-3 and CES 1-4 were determined using the Stain Test Method. Results are provided in Table 3.e958. 2. 39.27.3ruc 120-04= = - 2n== X0EaS02E ΔL ΔaΔbΔ te583. 1. 004.802.2sob1 - - 1r 7 = === X Eu 2E L T02Δ ΔaΔbΔ e8102401r1u..c810- .019 = = -.1== Xn8Ea 2E L S0Δ ΔaΔbΔ 67e7r8. 5.02.707.4uc 81 -9 - 18= === EnCaE L S02Δ ΔaΔbΔ e756. 2. 58.25.3ruc 120-04= = - 20 == EnCaE L S02Δ ΔaΔbΔsmliF27d tete20s6..05.035.ao2 ob1 -7 = = -1=CEr2= E L CuT0a br2Δ Δ Δ ΔaelCfo91ee52. 0.c04.801.n1ruasEc 81 -n 98= = - 1==t ai0E La bsC S2Δ Δ Δ ΔeRenidat#oS eC e0. lpl . 0.3e mp 33l am << E SaSbbΔ ΔaTtlt - alhah) 5pen71]p3s s2ail2os 2- O1t0s AM%0 agF DH C0e[TG5(nini-1

[0124] Thus, the present disclosure provides, among other things, a clear coat, multilayer films comprising the clear coat, and methods of making the multilayer film. Various features and advantages of the present disclosure are set forth in the following claims.

Claims

What is claimed is:

1. A method of making a multilayered film, the method comprising: applying an aqueous polyurethane dispersion onto a carrier; curing the aqueous polyurethane dispersion to provide a thermoset clear coat having a first major surface opposite a second major surface, the second major surface adjacent the carrier; applying a polyurethane composition to the first major surface of the thermoset clear coat, the polyurethane composition forming a thermoplastic polyurethane layer, wherein the first major surface of the thermoset clear coat has available amino groups prior to application of the polyurethane composition, wherein the polyurethane composition has available isocyanate groups, and wherein the available amino groups of the thermoset clear coat react with the available isocyanate groups of the polyurethane composition.

2. The method of claim 1, further comprising applying an adhesive on a first major surface of the thermoplastic polyurethane layer that is opposite to a second major surface, the second major surface of the thermoplastic polyurethane layer adjacent to the first major surface of the thermoset clear coat.

3. The method of claim 2, wherein the adhesive is a pressure sensitive adhesive.

4. The method of claim 2, wherein the adhesive is a hot melt adhesive.

5. The method of claim 2, wherein the adhesive is a patterned adhesive.

6. The method of claim 1, wherein the aqueous polyurethane dispersion comprises a polyurethane, a crosslinking agent, and water.

7. The method of clam 6, wherein the polyurethane is the reaction product of a composition comprising a polyester polyol and an aliphatic diisocyanate.

8. The method of claim 6, wherein the crosslinking agent is a polyfunctional aziridine.

9. The method of claim 6, wherein the aqueous polyurethane dispersion further comprises at least one of a pH adjuster, a surfactant, a solvent, an ultraviolet absorber, a radical scavenger, a colorant, or a combination thereof.

10. The method of claim 6, wherein the aqueous polyurethane dispersion further comprises a coalescing solvent.

11. The method of claim 1, wherein the viscosity of the aqueous polyurethane dispersion ranges from 70 cps to 180 cps.

12. The method of clam 1, wherein the polyurethane composition comprises a diisocyanate, a polyester polyol having a melt temperature of at least 30º C, and a chain extender.

13. The method of claim 12, wherein the chain extender is 1,4-butanediol and the diisocyanate is an aliphatic diisocyanate.

13. The method of claim 12, wherein the polyurethane composition has an isocyanate index (i.e., NCO / OH ratio) ranging from 0.75 to 1.

25.

14. The method of claim 12, wherein the polyurethane composition has a hard segment content ranging from 35% to 65%.

15. The method of claim 12, wherein the polyurethane composition further comprises at least one of a catalyst, an ultraviolet absorber, a radical scavenger, a colorant, an antioxidant, or a combination thereof.

16. The method of claim 1, where the carrier comprises at least one of polyester, polypropylene, high density polyethylene, polymer coated papers, or combinations thereof.

17. The method of claim 1, wherein the thickness of the thermoset clear coat ranges from 5 μm to 50 μm.

18. The method of claim 1, wherein the thickness of the thermoplastic polyurethane layer ranges from 1 mils to 20 mils.

19. The method of claim 1, wherein the multilayered film has a ΔE and a Δb that are each no greater than 3 when subject to the Stain Test Method.

20. A multilayered film comprising: a carrier; a thermoset clear coat; and a thermoplastic polyurethane layer, wherein the thermoset clear coat is sandwiched between the carrier and the thermoplastic polyurethane layer, and wherein amino groups in the thermoset clear coat are crosslinked with isocyanate groups in the thermoplastic polyurethane layer.

21. The multilayered film of claim 20, further comprising an adhesive layer on a major surface of the thermoplastic polyurethane layer, wherein the thermoplastic polyurethane layer is sandwiched between the adhesive layer and the thermoset clear coat.

22. The multilayered film of clam 20, wherein the thermoset clear coat comprises a polyurethane that is the reaction product of a composition comprising a polyester polyol and an aliphatic diisocyanate.

23. The multilayered film of clam 20, wherein the thermoplastic polyurethane layer is the reaction product of a composition comprising a diisocyanate, a polyester polyol having a melt temperature of at least 30º C, and a chain extender.

24. The multilayered film of claim 20, wherein the thickness of the thermoset clear coat ranges from 5 μm to 50 μm.

25. The multilayered film of claim 20, wherein the thickness of the thermoplastic polyurethane layer ranges from 1 mils to 20 mils.

26. The multilayered film of claim 20, wherein the multilayered film has a ΔE and a Δb that are each no greater than 3 when subject to the Stain Test Method.

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