Patent Description:
Protective polymer films, such as polyurethane films, are used to provide a strong and durable shield for any bare or painted metal, glass or plastic surface that may be exposed to extreme environmental conditions or elements, such as heat, sun, moisture, wind, debris, dirt, or those due to inclement weather, such as for example, rain, hail, snow, or sleet, as well as harsh or corrosive chemicals such as solvents or the like. These protective polyurethane films are useful for preventing damage from abrasion, chipping, deterioration or discoloration, and wear of the surfaces under those circumstances. Such films may be used to protect, for example, cars, trucks, appliances, mobile devices, computers, electronic display screens, and more. These protective polyurethane films may be either thermoset or thermoplastic.

Thermoset polyurethanes typically exhibit better abrasion resistance, heat resistance, and hardness compared to thermoplastic polyurethanes. Because thermoset polyurethanes generally comprise a network of cross-linked polymer chains, thermoset polyurethanes are typically formed using expensive casting processes. In contrast, thermoplastic polyurethanes are able to flow at elevated temperatures. The flowability of thermoplastic polyurethanes allows their production by less expensive techniques, such as for example, injection molding or extrusion.

Interpenetrating polymer networks (IPNs) are combinations of two or more polymers which have been polymerized and/or crosslinked in the presence of each other. One approach for making cross-linked thermoplastic polyurethanes, described in <CIT>, involves formation of chemical bonds upon cross linking a polymer and a thermoplastic polyurethane (TPU) having terminal functional radically-polymerizable groups on both ends of the TPU. These interpenetrating polymer networks, or IPNs, can be seen as analogous to polymer alloys, a combination of different polymers which allows the composite to collectively have certain advantageous benefits derived from, and often specifically attributable to, the individual polymer forming the alloy. Examples of these attributes may include, for example, transparency or hardness.

The layers of a multilayer protective film may confer different properties and provide different advantages. For example, one layer may confer stain resistance, while another layer may confer chip resistance. It is therefore desirable to provide a multilayer, protective polymeric film comprising an IPN layer and a polymer layer that provides different advantages such as, for example, stain and scratch resistance as well as high gloss.

Patent application <CIT> describes a composition of matter comprising a hydrophobic or hydrophilic (or both) interpenetrating polymer network containing a non-ionic/ionic polymer and a hydrophobic thermoset or thermoplastic polymer, and articles made from such composition and methods of preparing such articles. The patent application also includes a process for preparing a hydrophobic/hydrophilic IPN or semi-IPN from a hydrophobic thermoset or thermoplastic polymer including the steps of placing an non-ionizable/ionizable monomer solution in contact with a hydrophobic thermoset or thermoplastic polymer, diffusing the monomer solution into the hydrophobic thermoset or thermoplastic polymer; and polymerizing the monomers to form a penetrating polymer inside the hydrophobic thermoset or thermoplastic polymer, thereby forming the IPN or semi - IPN.

Patent application <CIT> describes an article comprising two chemically grafted polymer layers comprising a hydrogel layer and an end-functionalized polyurethane layer. The patent application also includes methods of making and using the article.

Patent application <CIT> describes a composition of matter comprising a water-swellable PN or semi-IPN including a hydrophobic then no set or thermoplastic polymer and an ionic polymer, articles made from such composition and methods of using such articles. The patent application also includes a process for producing a water-swellable IPN or semi-IPN from a hydrophobic then no set or then no plastic polymer including the steps of placing an ionizable monomer solution in contact with a solid form of the hydrophobic then no set or then no plastic polymer; diffusing the ionizable monomer solution into the hydrophobic then no set or then no plastic polymer; and polymerizing the ionizable monomers to form a ionic polymer inside the hydrophobic then no set or then no plastic polymer, thereby forming the IPN or semi-IPN.

Patent application <CIT> describes a low refractive index composition that forms a low refractive index layer on an optical display. The display is formed having a co-crosslinked interpenetrating polymer network of a fluoropolymer phase and an acrylate phase. The fluoropolymer phase is preferably formed from fluoropolymers based on THV or FKM and having either a degree of unsaturation and/or containing a reactive cure site monomer in its polymer backbone. The acrylate phase includes a multifunctional acrylate crosslinker, and more preferably includes a perfluoropolyether acrylate crosslinker. The formed low refractive index layer has improved interfacial adhesion to other layers or substrates contained in the optical display.

The present disclosure generally relates to a thermoplastic polymer film comprising a multilayer film having an interpenetrating polymer network (IPN) layer and a polymer layer that possesses beneficial properties useful in protecting surfaces from harmful environmental conditions or elements.

The invention relates to a multilayer film and to a method of making a multilayer film as specified in the independent claims. Embodiments of the invention are given in the dependent claims.

According to the invention, the multilayer film comprises a first layer comprising an interpenetrating network. The interpenetrating network comprises a first thermoplastic polymer selected from the group consisting of a polyurethane, polycarbonate, polycaprolactone, and a combination thereof, and crosslinked components selected from the group consisting of triallyl isocyanurate (TAIC), triethylolpropane triacrylate (TMPTA), and di-trimethylolpropanetetraacrylate (DTMPTA), and tri-functional methacrylate, and a photoinitiator. The interpenetrating network comprises <NUM>% to <NUM>% by weight of the first thermoplastic polymer and <NUM>% to <NUM>% by weight of the crosslinked components. The second layer comprises one or more layers of a second thermoplastic polymer, wherein the second thermoplastic polymer is selected from the group consisting of a polyurethane, polycarbonate, polycaprolactone, and a combination thereof.

In one exemplary embodiment, the thermoplastic polyurethane may be an aliphatic, polycaprolactone-based thermoplastic polyurethane.

In certain embodiments, the interpenetrating network layer may have a dried Sharpie® ink removal by isopropanol wipe affording a value of greater than about <NUM>% light transmission. In some embodiments, the interpenetrating network layer may have a tar stain removal of between about <NUM> to about <NUM> Delta YI (change in yellowness index). In some embodiments, the interpenetrating network layer may have a scratch resistance of greater than about <NUM> gloss units. In some embodiments, the interpenetrating network layer may have a gloss of greater than about <NUM> gloss units.

The invention also relates to a method for making a multilayer film, comprising:.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

The present disclosure provides a thermoplastic polymer film comprising a multilayer film having an interpenetrating polymer network (IPN) layer and a polymer layer. The multilayer thermoplastic polymer film may possess beneficial and desirable properties useful in protecting surfaces from harmful environmental conditions or elements, such as for example, stain and scratch resistance as well as high gloss.

The thermoplastic polymer in the first and/or second layer can be a commercially available product. The thermoplastic polymer is a polyurethane, polycarbonate, polycaprolactone, or a combination thereof. Thermoplastic polyurethane polymers are typically formed by reacting polyols with polyisocyanates. The polyols can include polyester polyols, polyether polyols, polycarbonate polyols, and polycaprolactone polyols. In one embodiment, the polyol can be polycaprolactone-based. In another embodiment, the thermoplastic polyurethane can be an aliphatic, polycaprolactone-based thermoplastic polyurethane.

Polyisocyanates can include compounds having two or more isocyanate groups such as <NUM>,<NUM>'-diisocyanatodicyclohexylmethane (H12MDI).

Prior to crosslinking (i.e., curing), the interpenetrating network precursor comprises thermoplastic polymer and monomers. After crosslinking, the interpenetrating network comprises a thermoplastic polymer and crosslinked components, e.g. crosslinked monomers. The monomers and crosslinked components are chosen from triallyl isocyanurate (TAIC), triethylolpropane triacrylate (TMPTA), di-trimethylolpropane tetraacrylate (DTMPTA), and tri-functional methacrylate (Saret SR 517R).

In certain embodiments, the interpenetrating network or its precursor can include one or more ultraviolet (UV) photoinitiators. Suitable UV photoinitiators can include but are not limited to: <NUM>-hydroxy-cyclohexyl-phenyl ketone (Irgacure <NUM>), oxy-phenyl-acetic acid <NUM>-[<NUM> oxo-<NUM> phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic <NUM>-[<NUM>-hydroxy-ethoxy]-ethyl ester (e.g. Irgacure <NUM>), phosphine oxide, phenyl bis (<NUM>,<NUM>,<NUM>-trimethyl benzoyl) (e.g. Irgacure <NUM>), diphenyl (<NUM>,<NUM>,<NUM>-trimethylbenzoyl)-phosphine oxide (e.g. Darocure TPO or Genocure TPO ), methylbenzoylformate (e.g. Omnirad MBF or Irgacure MBF), oligo(<NUM>-hydroxy-<NUM>-methyl-<NUM>-(<NUM>-(<NUM>-methylvinyl)phenyl)propanone) (e.g. KIP <NUM>), <NUM>,<NUM>-dimethoxy-<NUM>,<NUM>-diphenyl-ethanone (e.g. BDK), ethyl phenyl (<NUM>,<NUM>,<NUM>-trimethylbenzoyl) phosphinate) (e.g., IGM Omnirad TPO-L), a mixture of <NUM> hydroxy-<NUM>-methylpropiophenone, ethyl (<NUM>,<NUM>,<NUM>-trimethylbenzoyl) (phenylphosphinate and oligo[<NUM>-hydroxy-<NUM>-methyl-<NUM>-[<NUM>-(<NUM>-methylvinyl)phenyl]propanone]) (e.g., IGM Omnirad BL-<NUM>), difunctional alpha-hydroxy ketone (e.g., IGM Esacure One), a blend of diphenyl(<NUM>,<NUM>,<NUM>-trimethylbenzoyl)-phosphine oxide and <NUM>- hydroxy-<NUM>-methyl-<NUM>-phenyl-propan-<NUM>-one) (e.g., IGM Omnirad <NUM>), a blend of piparazino based aminoalkylphenone and PPTTA) (e.g., IGM Omnipol <NUM>), (<NUM>,<NUM>-dihydro-<NUM>-(<NUM>-hydroxy-<NUM>-methyl-<NUM>-oxopropyl)-<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-[<NUM>-(<NUM>-hydroxy-<NUM>-methyl1-oxopropyl)phenyl]-<NUM>-indene; <NUM>,<NUM>-dihydro-<NUM>-(<NUM>-hydroxy-<NUM>-methyl-<NUM>-oxopropyl)-<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-[<NUM>-(<NUM>-hydroxy-<NUM>-methyl1-oxopropyl)phenyl]-<NUM>-indene and <NUM>-hydroxy-<NUM>-methylpropiophenone) (e.g., IGM Esacure KIP 100F), (diester of carboxymethoxy-benzophenone and polytetramethyleneglycol <NUM>) (e.g., IGM Omnipol BP), and (<NUM>-propanone, <NUM>,<NUM>'-(oxydi-<NUM>,<NUM>-phenylene)bis[<NUM>-hydroxy-<NUM>-methyl- and <NUM>-hydroxycyclohexyl phenyl ketone) (e.g., PL Industries PL-<NUM>).

The interpenetrating network layer and/or the thermoplastic polymer layer can contain additives, heat stabilizers, UV absorbers (such as Tinuvin <NUM>), etc. A typical heat stabilizer includes but is not limited to pentaerythritol tetrakis (<NUM>-(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl) propionate) (e.g., Irganox <NUM>).

The multilayer polymeric film of the present disclosure may have a first, interpenetrating network layer bonded to a major surface of a second, thermoplastic polymer layer. The two layers may be bonded directly, for example, during coextrusion. Alternatively, one layer may be extruded onto a release liner and then laminated to the other layer. In certain embodiments, the first, interpenetrating network layer may be bonded to a major surface of the second, thermoplastic polymer layer and an adhesive may be bonded to an opposite major surface of the second layer such that the second layer is between the first layer and the adhesive layer. In one embodiment, the adhesive may be a pressure sensitive adhesive (PSA).

According to an aspect of the disclosure, the thickness of the IPN layer can be up to about <NUM> mil. In one embodiment, the thickness of the IPN film may be in the range of about <NUM> mil to about <NUM> mil. In another embodiment, the thickness of the IPN film may be in the range of about <NUM> mil to about <NUM> mil.

According to another aspect of the disclosure, the thickness of the second, thermoplastic polymer layer can be up to about <NUM> mil. In one embodiment, the thickness of the thermoplastic polyurethane base layer may be in the range of about <NUM> mil to about <NUM> mil. In another embodiment, the thickness of the thermoplastic polyurethane base layer may be in the range of about <NUM> mil to about <NUM> mil.

The thickness of the multilayer film can be in the range of about <NUM> mil to about <NUM> mil. In one embodiment, the thickness of the IPN surface layer may be about <NUM> mil, and the thickness of the thermoplastic polyurethane base layer(s) may be about <NUM> mil. In another embodiment, the thickness of the IPN surface layer may be about <NUM> mil, and the thickness of the thermoplastic polyurethane base layer(s) may be about <NUM> mil.

The first layer can comprise various percentages by weight of the first thermoplastic polymer and the crosslinked components. In certain embodiments, the first layer may comprise about <NUM>% to about <NUM>% by weight of the first thermoplastic polymer, and about <NUM>% to about <NUM>% by weight of the crosslinked components. In another embodiment, the first thermoplastic polymer is about <NUM>% by weight, and the crosslinked components are about <NUM>% by weight of the first layer.

In accordance with an aspect of the disclosure, the multilayer polymeric film may possess a high gloss, and scratch and stain resistant properties. Gloss can be measured at an angle of <NUM> degrees (°) and calibrated using a black glass standard of <NUM> gloss units (GU) ("GU, <NUM>°" or "<NUM>° Gloss"). Stain resistance can be measured by methods known in the art, such as for example, by removal from the film of black permanent marker or tar after wiping with isopropyl alcohol or bug and tar remover, respectively. In certain embodiments, the first, IPN layer and/or the multilayer film may have a permanent or waterproof marker (e.g., Sharpic® marker) removal value of greater than about <NUM>% light transmission or equal to or less than <NUM> (on a scale of <NUM>-<NUM>, where <NUM> = no retained marker stain). In certain embodiments, the first, IPN layer and/or the multilayer film has a tar stain removal of less than about <NUM> Delta YI (change in yellowness index) or equal to or less than <NUM> (on a scale of <NUM>-<NUM>, where <NUM>=no retained tar stain).

In certain embodiments, the first, IPN layer and/or the multilayer film may have a scratch resistance of greater than about <NUM> gloss units. In certain embodiments, the first, IPN layer and/or the multilayer film may have a gloss of greater than about <NUM> gloss units. Scratch resistance can be measured using methods known in the art, such as for example, a method in which (<NUM>) initial gloss can be measured as specular reflection of incident light at <NUM> degrees (angle between the incident light and the perpendicular), (<NUM>) scratched gloss can be measured at the time of or soon after scratching (e.g., abrading with sandpaper), and (<NUM>) recovery gloss can be measured at a given time after scratching, e.g., <NUM> hours after scratching.

According to an aspect of the disclosure, the multilayer polymeric film may be clear or transparent, and may be suitable for certain applications such as for paint protection. However, it is understood that in some embodiments, the multilayer polymeric film may be colored as desired. For example, the thermoplastic polyurethane or the reactive mixture may comprise pigment or other coloring agent. The multilayer polymeric film may be shaped and sized to conform to a surface to be protected before application to the surface. For example, the multilayer polymeric film may be used to protect various parts of a vehicle from ultraviolet light, weather, scratches from debris such as dirt, rocks, etc..

In accordance with another aspect of the present disclosure, methods of making the multilayer polymeric film disclosed herein and comprising an IPN layer and a thermoplastic polymer layer are provided. Generally, the methods comprise combining a first thermoplastic polymer with monomers to form an IPN precursor, bonding the IPN precursor to a second thermoplastic polymer, and curing the IPN precursor. Alternatively, the IPN precursor layer may be deposited onto a release liner, cured, and then laminated to the second thermoplastic layer.

Combining the first thermoplastic polyurethane with monomers can be done using conventional methods, such as for example, using a Banbury mixing machine, Farrel continuous mixer (FCM™), Brabender instrument, or by compounding using a twin screw extruder. Imbibition can occur, for example, by combining a thermoplastic polyurethane polymer in pellet form with a solution comprising monomers, wherein the thermoplastic polyurethane polymer pellets imbibe the components of the solution.

The layers of the multilayer polymeric film can be formed using conventional methods known in the art such as extrusion, calendaring, and solvent casting. For example, the multilayer film can be formed by co-extrusion of the first IPN layer and the second thermoplastic polymer layer using a multi-manifold coextrusion die or a coextrusion feedblock approach. The layers may also be extruded sequentially. The methods may also include laminating the multilayer film to an adhesive layer such that the second thermoplastic polymer layer is "sandwiched" between the IPN layer and the adhesive layer. Adhesives may include acrylics, polyurethanes, silicones, styrene-butadiene block copolymers, styrene-isoprene block copolymers, epoxies, cyanosacrylates, etc. In one embodiment, the adhesive may be a pressure sensitive adhesive (PSA).

The IPN precursor layer may be crosslinked or cured by any suitable means including e-beam, ultraviolet light, irradiation, or heat. Curing may occur before or after bonding the IPN precursor layer to the second thermoplastic polymer layer.

Pellets of TPU 93A (aliphatic polycaprolactone based thermoplastic polyurethane, Lubrizol Corp. , Wickliffe, OH) were dissolved in tetrahydrofuran at <NUM> to give a solution of <NUM>% polymer. The solution was combined with varying amounts of TAIC (Sartomer Arkema) and a constant amount of photoinitiator Irgacure <NUM> (<NUM>-hydrocyclohexyl phenyl ketone) (BASF) and then cast onto a release liner.

After solvent evaporation at room temperature, then <NUM>, and finally <NUM>, transparent films of <NUM> to <NUM> thickness were obtained. The content of TAIC in the dried film varied from <NUM>% to greater than <NUM>%, while the content of Irgacure <NUM> was held at <NUM>%. The films were irradiated with UV light in a chamber flushed with nitrogen from <NUM> x <NUM> seconds to <NUM> minutes (continuously).

For assessment of stain resistance, the films were marked with a Sharpie® pen and with road tar, heated at <NUM> for <NUM> hour, and washed with isopropanol until there was no reduction in stain intensity. A film of the TPU 93A without additives and UV exposure served as a control. For assessment of film flexibility, the films were bent through <NUM> degrees to observe failure by cracking. The gel content of the crosslinked films was determined. Stain resistance was measured by marking the film with a Sharpic® pen and with road tar. The film was heated at <NUM> for <NUM> hour, and then washed with isopropanol until there was no further reduction in stain intensity.

Stain intensity of an untreated polyurethane film was rated as "<NUM>" and no visible stain as "<NUM>". Films containing <NUM>% or more of TAIC showed no retained stain (= <NUM>) for both Sharpie® and tar after <NUM>. of UV exposure; their gel content was at least <NUM>%. The control film showed a strong stain retention for both Sharpie® and tar (= <NUM>). Films that contained less than <NUM>% TAIC were flexible (showed no cracks on folding through <NUM> degrees) after a UV exposure of <NUM>. Films that contained <NUM>% of TAIC after a UV irradiation of <NUM> minute showed no retained Sharpic® stain and a trace of retained tar stain (= <NUM>); this film was folded several times through <NUM> degrees without cracking. Gloss was measured as specular reflection of incident light at <NUM> degrees. All UV crosslinked films were transparent, colorless and showed high gloss.

A UV-curable formulation was prepared by imbibing TAIC and various additives into pellets of TPU 93A. The overall mixture had the following composition shown in Table <NUM>. Silmer ACR Di-<NUM> (Siltech Corp. ) was included to prevent self-adherence of imbibed pellets.

To a KitchenAid® mixer, equipped with wire blades and a heating base, was added <NUM> of polymer pellets with the mixer chamber heated to approximately <NUM>. The other components were combined to form a transparent liquid, which was added to the stirred pellets in small increments over time. The imbibing process was monitored by measuring the increase in weight of the imbibed pellets:.

After <NUM> hours of imbibing, the mixture was agitated for an additional <NUM> hours to assure a uniform distribution of all components. The pellets were rubbery and free-flowing. One aliquot of the imbibed pellets was dissolved in tetrahydrofuran to give a <NUM>% solids solution, which was cast onto a release liner, then dried to give a film of thickness approximately <NUM>. Another aliquot was compression molded at <NUM> between two sheets of release liners to give a film of thickness approximately <NUM>. Both films were irradiated with UV for <NUM> minute under nitrogen. The crosslinked films were transparent, colorless and flexible. They were stained with a Sharpic® pen and with road tar. There was no retained Sharpie® stain (= <NUM>) and a trace of retained tar stain (= <NUM>).

Tri- and tetra-functional acrylate monomers in TPU 93A were evaluated. TMPTA (Sartomer Arkema), TAIC, and DTMPTA (Sartomer Arkema) were solvent and melt blended with TPU 93A and evaluated for rate of crosslinking by UV, and for stain resistance.

All monomers were molecularly compatible with TPU 93A, gave transparent films, and were thermally stable at <NUM> for <NUM> hour in air. The monomers swelled TPU <NUM> pellets. The imbibed pellets were self-adherent. Addition of less than <NUM>% of hydrophobic fumed silica made them free-flowing. TAIC also dissolved TPU 93A. All monomers, with the appropriate photoinitiator (Irgacure <NUM> or mixtures of Irgacure <NUM> and Genocure TPO (Rahn)), crosslinked TPU 93A upon UV exposure in nitrogen to give stain (Sharpie®/tar) resistant films after UV exposure of sufficient length.

Solvent or melt compounding of TMPTA and TAIC at up to <NUM>% with TPU 93A, after UV crosslinking in nitrogen, afforded colorless films that were flexible and stain resistant towards Sharpie® pen mark and tar. Films crosslinked with TAIC were colorless with photoinitiators Irgacure <NUM>/Genocure TPO, while those with TMPTA and DTMPTA and the same photoiniators, and identically crosslinked with UV, had a slightly yellow tinge that faded with time and exposure to light.

Melt blending and compression molding of TPU 93A formulation with <NUM> to <NUM>% monomers and photoinitiators can be done at between <NUM> and <NUM> as suggested by evaluations with a Brabender mixing device at approximately <NUM> rpm using a sigma blade for about <NUM> to obtain a uniform mixture.

The gloss of films of the aliphatic polyurethane TPU 93A was related to its refractive index (nD = <NUM>). A higher refractive index affords higher gloss. The refractive index of all the monomers was close to that of the TPU 93A, and the monomer incorporation into the polymer followed by crosslinking gave the same gloss as that observed for virgin TPU 93A film.

The effect of length of time of UV irradiation on blends of TPU 93A and TMPTA or TAIC was evaluated. Blends containing TPU 93A (<NUM>%) <NUM>% TMPTA or <NUM>% TMPTA or <NUM>% TAIC and <NUM>% Irgacure <NUM> and <NUM>% GenocureTPO were solvent cast from tetrahydrofuran solution with additives onto a release liner to give a coating of thickness <NUM> after drying at <NUM>. The films were transparent and colorless. The films were cut into several pieces, which were then illuminated with UV in nitrogen for <NUM>, <NUM>, <NUM>, <NUM> (and <NUM>) seconds (sec), followed by marking with a Sharpie® pen and tar. On increasing the illumination time, the films became stiffer. The films were extracted with tetrahydrofuran to determine the gel content. Results are shown in Table <NUM>.

A test with films containing the <NUM>% TMPTA or <NUM>% TAIC compositions prepared by compression molding at <NUM> gave nearly identical results for stain resistance.

Imbibing of TMPTA into TPU 93A was performed. Fifteen grams of TPU 93A, <NUM> TMPTA, <NUM> Irgacure <NUM> and <NUM> Genorad TPO were placed in a screw-cap tube together with about <NUM> of heptane. The mixture was held at <NUM> for <NUM> days (or <NUM> for about <NUM> hours). The heptane was allowed to evaporate at room temperature, and traces of it were removed by heating at <NUM>/<NUM> to give <NUM> of slightly self-adhered pellets. The pellets had a melt index of <NUM>/<NUM> at <NUM> and of <NUM>/<NUM> at <NUM> (load: <NUM>; die: <NUM>). The pellets were compression molded to slabs at <NUM> to a thickness of <NUM>-<NUM> mils and showed the same stain resistance behavior as film of the same composition obtained by solvent casting. DTMPTA was imbibed into TPU 93A in the same manner. The time required to complete the imbibing was longer than that observed for TMPTA. The DTMPTA blend gave the same stain resistance and flexibility as the TMPTA blend.

The melt index test was repeated for a blend of <NUM>% of TMPTA and <NUM>% Irgacure <NUM> and <NUM>% Genocure TPO in TPU 93A from <NUM> to <NUM>. The data suggests that such blends are extrudable at <NUM> to <NUM>.

Formulation LR00736-<NUM>, comprising <NUM>% CLC 93A-V pellets (aliphatic polycaprolactone TPU; Lubrizol Corp. ) imbibed with <NUM>% TAIC and <NUM>% <NUM>,<NUM>-dimethoxy-<NUM>,<NUM>-diphenyl-ethanone (IGM) was compared to commercially available protective films (XPEL Ultimate (XPEL Tech. ; San Antonio, TX); SunTek (Eastman Chem. ; Martinsville, VA); PremiumShield Elite (PremiumShield, Holliston, MA), and ArgoGUARD <NUM> (Argotec, Greenfield, MA)) for Sharpie® and tar stain removal, scratch resistance, and gloss.

Sharpie® stain removal was evaluated by applying a coating of black marker to the film, allowing the marker to set for <NUM> minutes, followed by a vigorous <NUM>% isopropyl alcohol (IPA) wiping using an IPA soaked cotton cloth until no more ink was removable. Sharpie® stain removal was measured as % light transmission (%LT) using a transparency/clarity meter.

Tar removal was evaluated by applying a blotch of tar to the film, baking the tar/film specimen for <NUM> minutes at <NUM>. Then, the tar was removed using GM Bug and Tar Remover with a cotton cloth. Tar removal was measured as change in yellowness index (delta YI) using a spectrometer.

Gloss and scratch resistance were measured in gloss units at <NUM> degrees at time zero (initial gloss), scratch time, and <NUM> hours after scratch. Scratch was done by abrading using <NUM> grit sandpaper on a <NUM> gram sled for a fixed number of abrading wipes under a constant load. LR00736-<NUM> demonstrated Sharpie® mark removal as good as the competitive topcoats (XPEL Ultimate, SunTek, and PremiumShield Elite) and much better than ArgoGUARD <NUM>. LR00736-<NUM> demonstrated tar stain removal better than the competitive topcoats (XPEL Ultimate, SunTek, and PremiumShield Elite) and much better than ArgoGUARD <NUM>. LR00736-<NUM> demonstrated high gloss. Scratch recovery was minimal; however, the film did not scratch much. Results are shown in Table <NUM>.

<NUM>% CLC 93A-V pellets (aliphatic polycaprolactone TPU; Lubrizol Corp. ) were imbibed with <NUM>% TAIC and <NUM>% <NUM>,<NUM>-dimethoxy-<NUM>,<NUM>-diphenyl-ethanone (BDK) or <NUM>% Irgacure <NUM> to form an interpenetrating network precursor blend. The IPN precursor blend was coextruded at about <NUM> to about <NUM> or laminated to ArgoGUARD <NUM>. The coextruded or laminated film was cured with UV light with PET used as an oxygen barrier to form a multilayer polymeric film comprising an interpenetrating polymer network (IPN) within a thermoplastic polyurethane (TPU) film. The IPN layer had a thickness of about <NUM> mil. The TPU layer had a thickness of about <NUM> mil. The multilayer film had a Sharpic® stain removal value of greater than about <NUM>% light transmission, a tar stain removal of less than about <NUM> Delta YI, a scratch resistance of greater than about <NUM> gloss units, and a gloss of greater than about <NUM> gloss units.

<NUM>% SR355 (DTMPTA (Sartomer Arkema)), <NUM>% BDK and <NUM>% heat stabilizer were pre-mixed and incorporated at a <NUM>% loading into <NUM>% CLC 93A-V pellets using a twin screw extruder equipped with liquid injection and underwater pelletizing capabilities. The IPN layer was extruded using these pellets at a loading of <NUM>% in a layer about <NUM> mils in thickness while a TPU layer comprised of just CLC 93A-V was co-extruded simultaneously with an individual thickness of about <NUM> mils. No interlayer instability was present at the interface of the two layers. The complete construction was laminated to PET with the IPN layer at the interface. The film was UV cured through the PET at <NUM> feet per minute, six times, using mercury microwave lamps within <NUM> hours of extrusion. The film was coated with pressure sensitive adhesive at a later date.

<FIG> illustrates a cross-sectional view of the film <NUM> produced in Example <NUM>. In the embodiment shown, the PET layer may have a thickness of approximately <NUM> mil. The IPN layer may have a thickness of approximately <NUM> mil. The CLC 93A-V layer may have a thickness of approximately <NUM> mil. The test results of this material, identified as LR01267-<NUM>, are shown in Table <NUM> below.

Claim 1:
A multilayer film comprising:
a first layer comprising an interpenetrating network, the interpenetrating network comprising:
a first thermoplastic polymer selected from the group consisting of a polyurethane, polycarbonate, polycaprolactone, and a combination thereof,
crosslinked components selected from the group consisting of triallyl isocyanurate (TAIC), triethylolpropane triacrylate (TMPTA), and di-trimethylolpropanetetraacrylate (DTMPTA), and tri-functional methacrylate, and
a photoinitiator,
wherein the interpenetrating network comprises <NUM>% to <NUM>% by weight of the first thermoplastic polymer and <NUM>% to <NUM>% by weight of the crosslinked components; and
a second layer comprising one or more layers of a second thermoplastic polymer, wherein the second thermoplastic polymer is selected from the group consisting of a polyurethane, polycarbonate, polycaprolactone, and a combination thereof.