WO2008039659A2

WO2008039659A2 - Corrosion resistant metallized films and methods of making the same

Info

Publication number: WO2008039659A2
Application number: PCT/US2007/078739
Authority: WO
Inventors: Michael A. Johnson; Ronald S. Steelman; William J. Hunt
Original assignee: 3M Innovative Properties Company
Priority date: 2006-09-27
Filing date: 2007-09-18
Publication date: 2008-04-03
Also published as: WO2008039659A3

Abstract

Corrosion resistant metallized films and methods of making the same are disclosed.

Description

CORROSION RESISTANT METALLIZED FILMS AND METHODS

OF MAKING THE SAME

BACKGROUND

Metallized films are widely used to form three-dimensional decorative articles that may be attached to a variety of industrial and consumer items such as motorized vehicles, boats, furniture, building materials, appliances, and the like. These decorative articles may be substituted for their metal counterparts resulting in at least one of the following: lighter weight, lower manufacturing costs, better weather resistance, design flexibility, and sharper detail.

Corrosion of metallized films is an ongoing concern. Typically, metallized films are formed as sheet materials having an overall length, /, and an overall width, w. In some cases, the sheet material is subsequently slit to form tapes having a tape length, l_t, and a tape width, Wf, wherein the total number of tapes, x, times the tape width, Wf, substantially equals overall width, w. Outer edges along tape length, /, having an exposed portion of the metal layer of the metallized film are especially prone to corrode if exposed to the elements. Traditionally, the edges of metallized films constructed from corrosion susceptible metals have been encapsulated or overcoated with a protective coating to shield and protect the exposed, corrosion susceptible metal edge from the elements.

There exists a need in the art to enhance the corrosion resistance of metallized films, and especially metallized films constructed from corrosion susceptible metals having at least one edge that exposes a portion of a metal layer of the metallized film.

SUMMARY

In one aspect, the present invention provides a corrosion-resistant metallized film comprising: a polymeric primer layer having opposite surfaces comprising a first surface and an outer surface; a metal layer adjacent the first surface of the polymeric primer layer; and a polymeric protective layer adjacent the metal layer, the protective layer having opposite surfaces comprising a second surface and an outer surface, and the second surface being in contact with the metal layer; wherein the opposite surfaces of at least one of the protective layer and the polymeric primer layer bear predetermined surface topographies, and wherein the first and second surfaces (i) have a similar surface charge, and (ii) jointly provide corrosion resistance to the metal layer.

At least one predetermined surface topography (for example, two predetermined surface topographies) is formed by at least partially cross-linking a cross-linkable composition while it is in contact with a forming substrate. In some of these embodiments, at least one forming substrate comprises a release liner. In some of these embodiments, at least one forming substrate comprises a mold.

In some embodiments, the metal layer is a visually continuous layer having a discontinuous conductivity. In some embodiments, the metal layer has a conductivity of less than about 10 mhos. In some embodiments, the metal layer has a surface resistivity of at least about 3 ohms/cm^. In some embodiments, the first and second surfaces have: (i) acidic functional groups on the first and second surfaces, (ii) basic functional groups on the first and second surfaces, (iii) a corona discharge or glow discharge surface treatment, (iv) both (i) and (iii), or (v) both (ii) and (iii). In some embodiments, the polymeric primer layer comprises at least one polymer or additive having acidic functional groups thereon, and the polymeric protective layer comprises at least one polymer or additive having acidic functional groups thereon.

In some embodiments, the polymeric protective layer comprises a polyurethane, a polymer or copolymer containing carboxyl groups thereon, a polyolefm, an ethylene/vinyl acetate/acid terpolymer, an ionomer, a polymer doped with one or more additives containing acidic or basic functional groups, or a combination thereof; and the polymeric primer layer comprises a polyurethane, a polymer or copolymer containing carboxyl groups thereon, a polyolefm, an ethylene/vinyl acetate/acid terpolymer, an ionomer, a polymer having acidic or basic functionality, a polymer doped with one or more additives containing acidic or basic functional groups, or a combination thereof.

In some embodiments, the polymeric protective layer comprises an optically clear layer comprising a polyurethane or a polymer or copolymer containing carboxyl groups thereon; and the polymeric primer layer comprises a polymer having acidic functionality, an additive having acidic functionality, or a combination thereof.

In some embodiments, the polymeric primer layer comprises an ethylene acrylic acid copolymer, an ethylene/vinyl acetate/acid terpolymer, a polyurethane, or a combination thereof.

In some embodiments, the polymeric primer layer comprises an outer adhesive surface opposite the metal layer. In some embodiments, the polymeric primer layer comprises a pressure sensitive adhesive layer. In some embodiments, the polymeric primer layer, the polymeric protective layer, or both, comprise at least one polymer and at least one of a mercapto-functional silane or a benzotriazole. In some embodiments, both the first surface and the second surface have an overall positive surface charge. In some embodiments, the metal layer comprises areas of metallic material, the areas being attached to bond sites along the second surface, wherein the bond sites correspond to a functional group or a treated surface area along the second surface of the polymeric protective layer. In some embodiments, the polymeric primer layer, the polymeric protective layer, or both, are at least partially cross-linked. In some embodiments, the polymeric primer layer, the polymeric protective layer, or both, comprise water-borne polymeric material.

In some embodiments, the polymeric protective layer comprises at least one polymer and at least one silicone wetting agent. In some embodiments, the metal layer comprises indium, aluminum, tin, stainless steel, copper, silver, gold, chromium, nickel, alloys thereof, or a combination thereof. In some embodiments, the metal layer has a surface resistivity of at least about 10 ohms/cm^.

In some embodiments, the corrosion-resistant metallized film further comprises at least one additional layer attached to an outer surface of the polymeric primer layer opposite the first surface, the outer surface of the protective layer opposite the second surface, or both.

In some embodiments, the corrosion-resistant metallized film further comprises at least one adhesive layer attached to an outer surface of the polymeric primer layer opposite the first surface or an outer surface of an additional layer attached to an outer surface of the polymeric primer layer opposite the first surface. In some embodiments, the at least one adhesive layer comprises a pressure sensitive adhesive layer. In some embodiments, the corrosion-resistant metallized film further comprises at least one release liner on at least one outermost surface of the corrosion-resistant metallized film. In some embodiments, the at least one release liner provides topographical features to one or both of the outermost surfaces of the corrosion-resistant metallized film.

In another aspect, the present invention provides a thermoformable article comprising at least one thermoformable layer and at least one corrosion-resistant metallized film according to the present invention.

In another aspect, the present invention provides a method of forming a corrosion-resistant metallized film, the method comprising the steps of: providing a polymeric protective layer comprising a first cross-linkable composition and having a first surface with an overall positive or negative surface charge; providing a polymeric primer layer comprising a second cross-linkable composition and having a second surface with an overall surface charge similar to the first surface; and providing a metal layer in contact with, and between, the first and second surfaces, wherein at least one of the polymeric protective layer and the polymeric primer layer is made by a method comprising: forming a rolling bank of the corresponding cross- linkable composition, wherein the rolling bank contacts first and second forming substrates; passing the first and second substrates with the cross-linkable composition therebetween through a nip; and at least partially cross-linking the cross-linkable composition to provide the corresponding polymeric layer.

In some embodiments, wherein the corresponding cross-linkable composition is the first cross-linkable composition, the second forming substrate comprises a release liner, and the metal layer and the polymeric primer layer are provided by: removing the release liner from the polymeric protective layer to expose the second outer surface, depositing the metal layer over at least a portion of the second outer surface of the polymeric protective layer, and applying the second cross-linkable composition over the metal layer before at least partially cross-linking the second cross-linkable composition. In some embodiments, wherein the corresponding cross-linkable composition is the first cross-linkable composition, the second forming substrate comprises a metallized layer on a surface of a carrier, the method further comprising: removing the carrier from the at least partially crosslinked polymeric protective layer to provide a metal layer on the at least partially crosslinked polymeric protective layer, wherein the polymeric primer layer is provided by applying the second cross-linkable composition over the metal layer, after the carrier is removed, and then at least partially cross-linking the second cross- linkable composition.

In some embodiments, the first and second forming substrates with the cross- linkable composition therebetween are passed through the nip under conditions sufficient to provide a substantially void-free layer of the cross-linkable composition.

The following embodiments are applicable to the inventive methods set forth hereinabove.

In some embodiments, the first cross-linkable composition comprises a two-part urethane cross-linkable composition. In some embodiments, the first cross-linkable composition is solvent-free.

In some embodiments, the metal layer has a surface resistivity of at least about 10 ohms/cm^.

In some embodiments, the method further comprises surface treating the first surface, the second surface, or both using a corona discharge surface treatment, a flame surface treatment, or a glow discharge surface treatment.

In some embodiments, both the first surface and the second surface have an overall positive surface charge. In some embodiments, both the first surface and the second surface have an overall negative surface charge.

In some embodiments, the method further comprises attaching at least one additional layer to an outer surface of the polymeric primer layer opposite the first surface, an outer surface of the polymeric protective layer opposite the second surface, or both. In some embodiments, the polymeric primer layer, the polymeric protective layer, or both, are cross-linked.

In some embodiments, at least one adhesive layer is attached to an outer surface of the polymeric primer layer opposite the first surface or an outer surface of an additional layer attached to an outer surface of the polymeric primer layer opposite the first surface. In some embodiments, the at least one adhesive layer comprises a pressure sensitive adhesive layer. In some embodiments, the polymeric primer layer comprises an outer adhesive surface opposite the metal layer. In some embodiments, the polymeric primer layer comprises a pressure sensitive adhesive layer.

In some embodiments, the method further comprising providing topographical features to one or both outermost surfaces of the corrosion-resistant metallized film. In some embodiments, the method further comprises attaching a thermoformable layer to an outer surface of the polymeric primer layer opposite the first surface to form a thermoformable article. In some embodiments, the method further comprises thermoforming the thermoformable article. As used herein: the prefix "(meth)acryl" include acryl and/or methacryl; the term "polyurethane" refers generally to a reaction product of at least one polyisocyanate with at least one polyol, polyamine, and/or aminoalcohol unless otherwise specified; the term "predetermined surface topography" refers to a permanent surface topography formed by at least partially crosslinking a cross-linkable composition while it is in contact with a forming substrate having a topographical surface such that the permanent surface topography formed is the mirror image of, or substantially the mirror image of, the topographical surface of the forming substrate, although some minor localized imperfections are permitted; the term "solvent" refers to a volatile liquid component that is non-reactive with components used to form a polyurethane (for example, non-reactive with either or both of a polyol and polyisocyanate used to make a polyurethane); the term "solvent- free" means containing less than one weight percent of solvent; the term "thermosetting" refers to a material that permanently solidifies on being heated at a sufficient temperature or otherwise permanently hardens; and the term "thermoset" refers to a thermosetting material that has been solidified by heating or hardened.

These and other features and advantages of the present invention will become apparent after a review of the following detailed description of the disclosed embodiments and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

The above aspects may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which: Fig. 1 is a cross-sectional view of an exemplary corrosion-resistant metallized film of the present invention;

Fig. 2 is a perspective view of the individual layers in the exemplary corrosion- resistant metallized film of Fig. 1;

Fig. 3 A is a perspective view of an exemplary metal layer suitable for use in an exemplary corrosion-resistant metallized film of the present invention;

Fig. 3B is a perspective view of another exemplary metal layer suitable for use in an exemplary corrosion-resistant metallized film of the present invention;

Fig. 3C is a perspective view of an exemplary metal layer suitable for use in an exemplary corrosion-resistant metallized film of the present invention, wherein the exemplary metal layer comprises a discontinuous pattern having at least two separate metal areas;

Fig. 4A is a perspective view of an upper surface of an exemplary metal area suitable for use in a metal layer of a corrosion-resistant metallized film of the present invention, wherein the exemplary metal area comprises a visually continuous, but conductively discontinuous metal area;

Fig. 4B is a cross-sectional view of the exemplary metal area of Fig. 4A;

Fig. 5 is a cross-sectional view of an exemplary article comprising a corrosion- resistant metallized film of the present invention; and

Fig. 6 is a cross-sectional view of an exemplary article comprising a corrosion- resistant metallized film adhered to a substrate; and

Fig. 7 illustrates an exemplary process useful for preparing an exemplary polymeric protective layer suitable for use with the present invention.

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. To the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.

DETAILED DESCRIPTION

To promote an understanding of the principles of the present invention, descriptions of specific embodiments of the present invention follow and specific language is used to describe the specific embodiments. It will nevertheless be understood that no limitation of the scope of the present invention is intended by the use of specific language. Alterations, further modifications, and such further applications of the principles of the present invention discussed are contemplated as would normally occur to one ordinarily skilled in the art to which the invention pertains.

The present invention is directed to corrosion-resistant metallized films and methods of making corrosion-resistant metallized films. The present invention is further directed to articles of manufacture that include a corrosion-resistant metallized film, as well as methods of making articles of manufacture that include a corrosion-resistant metallized film.

An exemplary corrosion-resistant metallized film of the present invention is provided in Fig. 1. As shown in Fig. 1, exemplary corrosion-resistant metallized film 10 comprises polymeric primer layer 11, metal layer 12, and polymeric protective layer 13. In this exemplary embodiment, outer surfaces 121 and 122 of metal layer 12 are in direct contact with outer surface 131 of polymeric protective layer 13 and outer surface 111 of polymeric primer layer 11 , respectively.

The corrosion resistance of a given metallized film may be enhanced by selectively controlling one or more film construction parameters, each of which separately impacts the corrosion behavior of a given metallized film. Film construction parameters of particular interest in the present invention include (i) the surface structure, functionality, and surface charge of each of the surface layers adjacent the metal layer of the metallized film (for example, the surface structure, charge and functionality of outer surface 131 of polymeric protective layer 13 and outer surface 111 of polymeric primer layer 11), (ii) the hydrogen ion transport potential through or across the metal layer of the metallized film, and (iii) the surface resistivity and/or optical density of the metal layer within the metallized film. For example, the corrosion resistance of a given metallized film may be improved by maintaining a similar surface functionality or surface polarity (also referred to herein as a similar surface charge) on each side of the metal layer. As used herein, the term "similar surface charge" refers to surfaces next to the metal layer, wherein each surface has either an overall positive or negative surface so as to minimize the hydrogen ion (H⁺) transport potential across a metal layer positioned between the two surfaces. As described below, a "similar surface charge" may be the result of (i) a polymeric material within a given layer, wherein the polymeric material has positive or negative functional groups thereon; (ii) functionalized additives within a given layer, wherein the functionalized additives have a positive or negative charge; (iii) a surface treatment of a given layer surface, wherein the surface treatment results in a positive or negative charge; or (iv) a combination of (i) to (iii).

An exemplary corrosion-resistant metallized film of the present invention, which possesses this corrosion-enhancing film construction parameter, is illustrated in Fig. 2. As shown in Fig. 2, each of outer surface 131 of polymeric protective layer 13 and outer surface 111 of polymeric primer layer 11 has a positive surface charge or surface polarity on either side of metal layer 12. Although not shown, it should be understood that a similar degree of corrosion resistance would be expected if each outer surface 131 of polymeric protective layer 13 and outer surface 111 of polymeric primer layer 11 had a negative surface charge or surface polarity on either side of metal layer 12. As explained below, one or more techniques may be used to provide a particular surface charge or surface polarity to a given surface.

As illustrated in Figs. 1 and 2, corrosion-resistant metallized films of the present invention may comprise a number of individual layers, as well as possess one or more film construction parameters that impact the corrosion resistance of the metallized films. A description of the individual layers, the overall construction, and various film construction parameters of exemplary corrosion-resistant metallized films of the present invention are provided below. /. Corrosion-Resistant Metallized Films The corrosion-resistant metallized films of the present invention have a unique film structure, which results in enhanced corrosion resistance. As discussed above, one or more film construction parameters may be tailored to enhance the corrosion resistance of a given film construction. A description of each layer of the metallized films of the present invention, as well as film construction parameters for optimizing the corrosion resistance of the resulting metallized film is provided below.

A . Corrosion-Resistant Metallized Film Layers The corrosion-resistant metallized films of the present invention comprise at least the following individual layers.

1. Polymeric Protective Layer

The corrosion-resistant metallized films of the present invention comprise at least one polymeric protective layer, such as exemplary polymeric protective layer 13 of exemplary corrosion-resistant metallized film 10. The polymeric protective layer covers an adjacent metal layer, providing one or more of the following properties to the resulting metallized film: scratch resistance, impact resistance, water resistance, weather resistance, solvent resistance, resistance to oxidation, and resistance to degradation by ultraviolet radiation. In most embodiments, the polymeric protective layer completely covers the adjacent metal layer such that no portion of the metal layer is exposed.

The polymeric protective layer comprises one or more polymeric components, and is typically at least partially cross-linked, although this is not a requirement. In some embodiments of the present invention, only an outer surface of the polymeric protective layer adjacent the metal layer is cross-linked. In some embodiments of the present invention, cross-linked polymeric material is essentially distributed throughout an entire thickness of the polymeric protective layer (that is, the entire polymeric protective layer is subjected to a cross-linking step as opposed to just an outer surface of the polymeric protective layer).

The degree of cross-linking within the polymeric protective layer may vary to form a cross-linking gradient along a thickness of the polymeric protective layer, wherein an outer surface of the polymeric protective layer adjacent the metal layer has a relatively high degree of cross-linking, and the degree of cross-linking within the polymeric protective layer decreases as the distance from the outer surface of the polymeric protective layer adjacent the metal layer increases. For example, an outer surface of the polymeric protective layer opposite the metal layer may have a lesser degree of cross- linking, if any, relative to the degree of cross-linking of the outer surface of the polymeric protective layer adjacent the metal layer. The polymeric protective layer comprises one or more polymeric components. Suitable polymeric components include, for example, polyurethanes, polymers or copolymers containing polar groups thereon, polyolefms, ethylene/vinyl acetate/acid terpolymers, acrylate-based materials, acid or hydroxyl-functional polyesters, ionomers, fluoropolymers, fluoropolymer/acrylate blends, polymers doped with one or more additives containing acidic or basic functional groups, and combinations thereof. In one embodiment, the polymeric protective layer comprises one or more polymeric components, wherein at least one polymeric component has functional groups thereon resulting in an overall surface charge or surface polarity for at least an outer surface of the polymeric protective layer adjacent a metal layer (for example, outer surface 131 of polymeric protective layer 13 shown in Figs. 1-2). In this embodiment, the polymeric component having functional groups thereon may comprise, for example, polyurethane (for example, solvent-free polyurethane), a polymer or copolymer prepared from acidic monomers (for example, an ethylene acrylic acid (EAA) copolymer), and/or a polymer or copolymer prepared from basic monomers (for example, polyamides, or polyacrylamide copolymers).

The polymeric protective layer may further comprise one or more additives incorporated into the one or more polymeric components of the polymeric protective layer. Suitable additives include, for example, functionalized additives, non-functionalized additives, or a combination thereof. As used herein, the term "functionalized additives" is used to describe additives having functional groups thereon such that the additive is capable of providing and/or contributing to an overall surface charge or surface polarity for at least an outer surface of the polymeric protective layer adjacent a metal layer (for example, outer surface 131 of polymeric protective layer 13 shown in Figs. 1-2). Suitable functionalized additives include, for example, (i) additives having thereon an acidic functional group, which is capable of donating a hydrogen ion such as sulfonic acids, phosphoric acids, phosphonic acids, boric acids, carboxylic acids, mercapto groups, salts of these acids, esters of these acids, or combinations thereof, and (ii) additives having thereon a basic functional group such as, amine groups, phosphorous compounds such as triphenyl phosphite, alkoxy groups, nitrile groups, and heterocyclic moieties such as those described in U.S. Pat. No. 5,081,213 (Carlson). Exemplary functionalized additives include, for example, heterocyclic compounds such as benzotriazoles, oxygen or sulfur containing compounds such as mercaptopropyltrimethoxysilane and mercaptoacetic acid. Ideally, the functionalized additive is capable of interacting chemically with the metal so that a chemical interaction or chemical bond may be established directly between the functionalized additive and the metal. This ability to react with the metal enables a diffuse interface between the organic polymeric protective layer and inorganic metal layer, which aids in bridging the dissimilarity between the two layers.

As used herein, the term "non-functionalized additives" is used to describe additives that provide a minimal contribution to an overall surface charge or surface polarity to the polymeric protective layer. Suitable non-functionalized additives may include, for example, most dyes, most pigments, wetting agents such as surfactants, plasticizers, inert filler materials (for example, glass microspheres, silica, calcium carbonate), waxes and slip agents, and some UV stabilizers.

If present, the functionalized additives, non-functionalized additives, and a combination thereof may represent up to about 50 percent by weight (pbw) based on a totals weight of the polymeric protective layer, with the balance being one or more polymeric materials. Typically, if present, each individual functionalized additive or non- functionalized additive is present in an amount ranging from greater than about 0.05 pbw to about 20 pbw, preferably between about 0.1 and about 10 pbw, and most preferably between about 0.5 and about 5 pbw, based on a totals weight of the polymeric protective layer, with the balance being one or more polymeric materials.

The polymeric protective layer may also have one or more surface treatments to alter outer surface properties of the polymeric protective layer, especially the outer surface of the polymeric protective layer adjacent the metal layer (for example, outer layer 131 of polymeric protective layer 13 shown in Figs. 1-2). Any surface treatment capable of chemically grafting functional groups or oxidizing the surface of the polymeric protective layer is acceptable so long as no macroscopic degradation occurs within or on the surface of the polymeric protective layer. Suitable surface treatments include, for example, a corona discharge surface treatment, flame treatment, and glow discharge surface treatments. In one exemplary embodiment, the one or more surface treatments enhances the surface charge capacity or surface polarity of the outer surface of the polymeric protective layer adjacent the metal layer. For example, a glow discharge surface treatment may be used to increase the amount of oxygen covalently bonded to an outer surface of the polymeric protective layer adjacent the metal layer.

In some embodiments, the polymeric protective layer comprises one or more polymeric materials alone or in combination with one or more additives, wherein at least one of the polymeric materials or additives has acidic or basic functional groups thereon.

In a further exemplary embodiment, the polymeric protective layer comprises one or more polymeric materials alone or in combination with one or more additives, wherein (i) at least one of the polymeric materials or additives has acidic functional groups, (ii) at least one of the polymeric materials or additives has basic functional groups, (iii) the outer surface of the polymeric protective layer adjacent the metal layer has a corona discharge or glow discharge surface treatment, (iv) both (i) and (iii), or (v) both (ii) and (iii). In one exemplary embodiment, the polymeric protective layer comprises an aliphatic water-borne polyurethane resin such as those described in U.S. Pat. No. 6,071,621 (Falaas et al.). Commercially available aliphatic waterborne polyurethanes include, but are not limited to, materials sold under the trade designation NEOREZ (for example, NEOREZ SR 9699, XR 9679, and XR 9603) from DSM (Waalwijk, The Netherlands), and materials sold under the trade designation BAYHYDROL (for example, BAYHYDROL 121) from Bayer Corp. (Pittsburgh, PA). Alternative polymer dispersion resins include polyurethane and polyurethane acrylate dispersions sold under the trade designation ALBERDINGK (for example, ALBERDINGK U933) from Alberdingk

Boley, Inc. (Charlotte, NC). The polyurethane protective layer may be cross-linked by adding cross-linking materials such as aziridine compounds in the dispersion or by cross- linking after the film has been formed using such means as radiation, for example, UV light, or heat. In a further exemplary embodiment, the polymeric protective layer comprises a solvent-based polyurethane resin formed by the reaction of one or more polyols with a polyisocyanate. In some applications, it is desirable for the polyols and the polyisocyanates to be free of aromatic groups. Suitable polyols include, but are not limited to, materials commercially available under the trade designation DESMOPHEN from Bayer Corporation (Pittsburgh, PA). The polyols can be polyester polyols (for example, DESMOPHEN 631A, 650A, 651A, 670A, 680, 110, and 1150); polyether polyols (for example, DESMOPHEN 550U, 1600U, 1900U, and 1950U); or acrylic polyols (for example, DESMOPHEN A160SN, A575, and A450BA/A). The use of polyisocyanate compounds, compounds having more than two isocyanate groups, can result in the formation of cross-linked polyurethanes. Suitable polyisocyanate compounds include, but are not limited to, materials commercially available under the trade designation MONDUR and DESMODUR (for example, DESMODUR XP71 OO and

DESMODUR 3300) from Bayer Corporation (Pittsburgh, PA).

In a further exemplary embodiment, the polymeric protective layer comprises a polymer or copolymer containing (i) at least one polar group along the polymer chain, (ii) at least one olefmic portion, or (ii) both (i) and (ii). In some embodiments, the polar groups are acids groups, esters thereof, or salts thereof. For example, the polar groups are carboxylic acids, carboxylate esters, or carboxylate salts. Suitable carboxylic acids, carboxylate esters, and carboxylate salts include, for example, acrylic acid, C^ to C20 acrylate esters, acrylate salts, (meth)acrylic acid, C\ to C20 (meth)acrylate esters,

(meth)acrylate salts, or combinations thereof. Suitable methacrylate and acrylate esters typically contain up to about 20 carbon atoms or up to about 12 carbon atoms (excluding the acrylate and methacrylate portion of the molecules). In some embodiments, the methacrylate and acrylate esters contain about 4 to about 12 carbon atoms.

The olefmic portion of the polymer or copolymer can be formed by free radical polymerization of monomers such as, for example, ethylene, propylene, isobutylene, or combinations thereof. In some embodiments, the olefinic materials include an olefmic monomer having ethylenic unsaturation. For example, reacting a polyethylene oligomer or ethylene monomers with a monomer having a polar group can form a copolymer for use in the polymeric protective layer.

In some embodiments, the copolymer is a reaction product of an olefinic monomer having ethylenic unsaturation with a second monomer selected from (meth)acrylic acid, a

Cj to C20 (meth)acrylate ester, a (meth)acrylate salt, acrylic acid, a Cj to C20 acrylate ester, an acrylate salt, or a combination thereof. The copolymer can be prepared using about 80 to about 99 weight percent of the olefinic monomer and about 1 to about 20 weight percent or the second monomer. For example, the copolymer can be prepared by copolymerizing about 83 to about 97 weight percent of the olefinic monomer and about 3 to about 17 weight percent acrylic acid, a Cj to C20 acrylate ester, an acrylate salt, (meth)acrylic acid, a Cj to C20 (meth)acrylate ester, a (meth)acrylate salt, or combinations thereof. In another example, the copolymer contains from about 90 to about 96 weight percent of the olefinic monomer and about 4 to about 10 weight percent acrylic acid, a Cj to C20 acrylate ester, an acrylate salt, (meth)acrylic acid, a Cj to C20 (meth)acrylate ester, a (meth)acrylate salt, or combinations thereof.

If salts of a methacrylate or acrylate group are present in the polymer or copolymer, the positive ion of the salt is typically an alkali metal ion, an alkaline earth metal ion, or a transition metal ion. For example, the positive ion may include, for example, sodium, potassium, calcium, magnesium, or zinc. In some embodiments, the polymeric protective layer includes a copolymer such as, for example, poly(ethylene-co-(meth)acrylic acid) or poly(ethylene-co-acrylic acid). Commercially available copolymers suitable for use in the polymeric protective layer include, for example, copolymers available from Dow Chemical Company (Midland, MI) under the trade designation PRIMACOR such as PRIMACOR 3330, which has 6.5% acrylic acid and 93.5% ethylene; copolymers commercially available from DuPont

(Wilmington, DE) under the trade designation NUCREL such as NUCREL 0403 (a copolymer of ethylene and methacrylic acid); copolymers commercially available under the trade designation ELVALOY (copolymers of ethylene with butyl acrylate, ethyl acrylate, or methyl acrylate); and copolymers commercially available under the trade designation SURLYN (ionomer of ethylene and acrylic acid).

The one or more polymeric materials used to form the polymeric protective layer may be cross-linked if desired. For example, the above-described water-borne polyurethane compositions can be cross-linked by the addition of a cross-linking agent (for example, less than about 3 weight percent) such as diaziridine. A commercially available diaziridine is sold under the trade designation NEOCRYL (for example,

NEOCRYL CX-100) from DSM (Waalwijk, The Netherlands). The above-described solvent-based polyurethane resin may be cross-linked, for example, by reaction with a cross-linking or curing agent such as a melamine resin. Further, the above-described polymers or copolymers containing (i) at least one polar group along the polymer chain, (ii) at least one olefmic portion, or (iii) both (i) and (ii), may be cross-linked, for example, using electron beam radiation. In some embodiments, the polymeric protective layer may be provided as a preformed layer such as a self-supporting film or may be cast from a solution onto a release liner. For example, when the polymeric protective layer is an aliphatic water- borne polyurethane resin, the aqueous urethane dispersion can be cast onto a release liner such as a bare or release coated polyester film. The cast urethane dispersion can then be dried to remove water. In another example, solvent-containing mixture of a polyisocyanate and a polyol can be cast onto a release liner. The cast mixture can then be dried to remove any solvent.

If the polymeric protective layer is formed (for example, by casting a polymer solution or dispersion) on a release liner, the release liner may be used to provide topographical features to the outer surface of the polymeric protective layer. For example, the release liner may provide a uniform pattern of valleys and/or ridges along the outer surface of the polymeric protective layer. Alternatively, the release liner may have a randomly textured pattern to provide a matte surface to the surface. In other embodiments, the release liner may be used to provide the outer surface of the polymeric protective layer with a substantially smooth surface.

If desired, cross-linking of the polymeric protective layer may be achieved using any suitable known cross-linking technique including, for example, (i) chemically cross- linking using reactive groups on the one or more polymeric materials, (ii) chemically cross-linking using a cross-linking additive used in combination with the one or more polymeric materials, (iii) physically cross-linking one or more polymeric materials using a cross-linking step, such as exposing the one or more polymeric materials to a cross-linking amount of radiation (for example, electron beam radiation), or (iv) a combination of (i), (ii) and (iii). Other physical cross-linking steps suitable for use in the present invention include, for example, exposure to ionizing forms of radiation such as gamma radiation, x- rays and ultraviolet light.

Typically, the dosage is as high as possible without unduly causing the polymer to undergo chain scission reactions that are in excess of the cross-linking reactions. Loss of molecular weight may be an indicator that irradiation has unduly degraded the polymer. Accordingly, for polymers that tend to undergo chain scission reactions, the radiation dosage is typically limited such that the weight average molecular weight of the irradiated polymer is at least about 90%, at least about 95%, or at least about 99% of that of an otherwise identical copolymer that has not been irradiated. The weight average molecular weight of the cross-linked copolymer is preferably greater than the weight average molecular weight of an otherwise identical copolymer that has not been cross-linked.

In some embodiments, the polymeric protective layer may be formed by combining reactive component(s) (for example, monomers), optionally in the presence of non-reactive component(s), in an appropriate stoichiometric ratio and then causing them to react with one another. For example, in the case of an epoxy resin, use of only mono functional monomers will typically result in formation of linear polymer, however the inclusion of polyepoxides and/or polyfunctional cross-linkers will typically result in at least partially crosslinked polymeric material.

Similarly a two-part-urethane may be used as a precursor composition for forming the polymeric protective layer. For example, copolymerization of a diol/diamine/or monoamino monohydroxy alcohol with a diisocyanate will typically result in a linear polyurethane. In order to obtain an at least partially cross-linked polyurethane, at least one component (that is, a polyisocyanate, a polyol, a polyamine, and/or an aminoalcohol) should have an average reactive functionality of greater than 2 (for example, polyisocyanates having more than two isocyanate groups or polyols, polyamines, and/or aminoalcohols having more than two isocyanate-reactive groups).

Suitable polyols include, for example, materials commercially available under the trade designations DESMOPHEN from Bayer Corporation (Pittsburgh, PA), K-FLEX from King Industries (Norwalk, CT), and FOMREZ from Witco Corp. (Greenwich, CT). The polyols may be polyester polyols (for example, DESMOPHEN 63 IA, 650A, 65 IA, 670A, 680, 110, and 1150; KFLEX 188; and FOMREZ 55-112); polyether polyols (for example, DESMOPHEN 550U, 1600U, 1900U, and 1950U); or acrylic polyols (for example, DEMOPHEN A160SN, A575, and A450BA/A).

Suitable polyamines include, for example: aliphatic polyamines such as, for example, ethylene diamine, 1 ,2-diaminopropane, 2,5-diamino-2,5-dimethylhexane, 1,11- diaminoundecane, 1,12-diaminododecane, 2,4- and/or 2, 6-hexahydrotoluylenediamine, and 2,4'-diamino-dicyclohexylmethane; and aromatic polyamines such as, for example, 2,4- and/or 2,6-diaminotoluene and 2,4'- and/or 4,4'-diaminodiphenylmethane; amine- terminated polymers such as, for example, those available from Huntsman Chemical (Salt Lake City, UT), under the trade designation JEFFAMINE polypropylene glycol diamines (for example, JEFFAMINE XTJ-510) and those available from Noveon Corp. (Cleveland, OH) under the trade designation HYCAR ATBN (amine-terminated acrylonitrile butadiene copolymers), and those disclosed in U.S. Pat. No. 3,436,359 (Hubin et al.) and U.S. Pat. No. 4,833,213 (Leir et al.) (amine-terminated polyethers, and polytetrahydrofuran diamines); and combinations thereof.

Suitable aminoalcohols, for example, 2-aminoethanol, 3-aminopropan-l-ol, alkyl- substituted version of the foregoing, and combinations thereof.

Suitable polyisocyanate compounds include, for example: aromatic diisocyanates (for example, 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; polycarbodiimide -modified methylenediphenylene 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; and l-chloromethyl-2,4-diisocyanato benzene), aromatic-aliphatic diisocyanates (for example, m-xylylene diisocyanate and tetramethyl- m-xylylene diisocyanate); aliphatic diisocyanates (for example, 1,4-diisocyanatobutane; 1,6-diisocyanatohexane; 1,12-diisocyanatododecane; and 2-methyl-l,5- diisocyanatopentane); cycloaliphatic diisocyanates (for example, methylenedicyclohexylene-4,4'-diisocyanate; 3-isocyanatomethyl-3,5,5- trimethylcyclohexyl isocyanate (isophorone diisocyanate); 2,2,4-trimethylhexyl diisocyanate; and cyclohexylene-l,4-diisocyanate), polymeric or oligomeric compounds (for example, polyoxyalkylene, polyester, polybutadienyl, and the like) terminated by two isocyanate functional groups (for example, the diurethane of toluene-2,4-diisocyanate- terminated polypropylene oxide glycol); polyisocyanates commercially available under the trade designation MONDUR or DESMODUR (for example, DESMODUR XP7100 and DESMODUR 3300) from Bayer Corporation (Pittsburgh, PA); and combinations thereof.

In general, the amounts of polyisocyanate to polyol, polyamine, and/or aminoalcohol are selected in approximately stoichiometrically equivalent amounts, although in some cases it may be desirable to adjust the relative amounts to other ratios. Typically, the equivalent ratio of polyisocyanate(s) to polyol(s), polyamine(s), and/or aminoalcohol(s) is in a ratio of from 1 :3 to 3:1. Those skilled in the art will recognize that any excess isocyanate present after cross-linking will typically react with materials having reactive hydrogens (for example, adventitious moisture, alcohols, amines, etc.).

The polymeric protective layer may have a high or low gloss surface, as desired. Additionally, the polymeric protective layer may have high or low reflectivity, as desired. The polymeric protective layer is desirably transparent to visible radiation so that the underlying metal layer is visible though the polymeric protective layer. As used herein, the term "transparent" refers to materials that allow at least about 50 percent of visible radiation to pass through the materials. For example, the transparent material may pass at least about 75 percent, at least about 80 percent, at least about 85 percent, at least about 90 percent, or at least about 95 percent of visible radiation. In some applications, the polymeric protective layer is colored yet transparent. For example, the polymeric protective layer may contain dyes and/or pigments in order to provide a color to the polymeric protective layer.

In some embodiments, the polymeric protective layer is formed between two forming substrates (for example, two release liners or two pieces of a mold). In one exemplary embodiment, forming substrates comprise release liners. Suitable release liners for the polymeric protective layer include, for example, carriers (for example, polymer films or papers), optionally coated with a low surface energy coating, that releasably adheres to that material, typically without any adhesive transfer. Suitable carriers may include films such as biaxially oriented polyester and papers that may be coated or printed with a composition that will enable release from the polyurethane compositions. Suitable low surface energy coatings may include, for example, those formed from polyacrylics, silicone, and/or fluorochemicals. In these embodiments, the release liners may impart predetermined topographical features to both the outer surface of the polymeric protective layer and the surface of the polymeric protective layer that is adjacent to the metallic layer

(that is, the second outer surface of the polymeric protective layer). While the release liners have a predetermined pattern, either or both of the release liners may appear to the unaided eye as being textured or smooth. The ability to control the topography of the second outer surface of the polymeric protective layer allows facile control of the final appearance of the metal layer, and hence the appearance of the metallized film. For example, release liners may be used to provide a uniform pattern of valleys and/or ridges along the first and/or second outer surfaces of the polymeric protective layer. In other embodiments, the release liners may be chosen to provide the first and/or second outer surfaces of the polymeric protective layer with a substantially smooth surface. Alternatively, the release liners may impart a randomly textured or matte surface to the first and/or second outer surfaces of the polymeric protective layer. Accordingly, release liners suitable for use in the present invention may include, for example, release liners disclosed in U.S. Pat. No. 6,984,427 (Galkiewicz et al.), the disclosure of which is incorporated herein by reference.

In another exemplary embodiment, the metal layer is deposited (for example, by vapor deposition techniques) onto a carrier (for example, a polyester carrier) and the combination of metal layer and carrier is used as one forming substrate while a release liner is used as the other forming substrate. In this embodiment, the metal layer contacts the rolling bank of cross-linkable material. After at least partially cross-linking the cross- linkable material, the carrier is removed from the metal layer, which is then supported on the polymeric protective layer. The polymeric primer layer is then applied to the metal layer.

In some embodiments of the present invention, an outer surface of the polymeric protective layer, especially the outer surface opposite the metal layer, may be embossed to provide a pattern in the outer surface prior to or after joining the polymeric protective layer with a metal layer. Embossing methods suitable for use in the present invention include, for example, embossing methods disclosed in U.S. Pat. No. 5,897,930 (Calhoun et al.), the disclosure of which is incorporated herein by reference.

In some embodiments of the present invention, the outer surface of the polymeric protective layer adjacent the metal layer may be a substantially flat, smooth, planar surface having very little, if any, topographical features thereon. As used herein, the term "planar" is used to describe a surface of a layer that is substantially within the same plane. In these embodiments, a subsequently applied metal layer may provide the metallized film with a mirror-like appearance. In other embodiments of the present invention, the outer surface of the polymeric protective layer adjacent the metal layer may have a non-planar surface, such as a surface having topographical features thereon. As described above, an embossing technique may be used to provide the outer surface of the polymeric protective layer adjacent the metal layer with topographical features. Other techniques may include, for example, the use of another release liner having topographical features therein to form the outer surface of the polymeric protective layer adjacent the metal layer. In these embodiments, a subsequently applied metal layer may provide the metallized film with an alternative appearance.

Advantageously, by applying low viscosity polymerizable materials onto the metal layer, it is typically possible to achieve good penetration of the polymerizable materials into void areas of the metal layer resulting in good adhesion.

The polymeric protective layer typically has an average thickness of at least about 5 micrometers although the polymeric protective layer may have any desired thickness. In some applications, the polymeric protective layer has a thickness of at least about 10 micrometers, at least about 15 micrometers, at least about 20 micrometers, or at least about 25 micrometers. The thickness of the polymeric protective layer is usually less than about 250 micrometers, although there is no limitation on the thickness of the polymeric protective layer. In some applications, the polymeric protective layer has a thickness less than about 40 micrometers, less than about 35 micrometers, or less than about 30 micrometers. For example, the thickness may be in the range of about 5 to about 50 micrometers, or about 10 to about 40 micrometers, or about 20 to about 30 micrometers.

The polymeric protective layer may be formed by combining at least one crosslinkable material between two forming substrates. An exemplary process for forming the polymeric protective layer is shown for example in Fig. 7. Referring now to Fig. 7, reactive component(s) 703 is/are fed into static mixer 710. The mixed component(s) are then fed to form rolling bank 715 which is disposed ahead of and between first and second forming substrates 721, 722 which are unwound from feed rolls 723, 724. As first and second forming substrates 721, 722 advance through nip 730 formed by first platen 740 and notch bar 735 entrapped air bubbles 717 are substantially or completely removed to give layer 750 which, after passing insulation barrier 760, contacts heated platen 765 which facilitates cross-linking (for example, curing) of the reactive component(s) to form an at least partially cross-linked polymeric protective layer 770 disposed between first and second forming substrates 721, 722. In some embodiments, (for example, those wherein the forming substrates are release liners) first forming substrate 721 is then removed to expose a surface of the polymeric protective layer on which subsequently metallization occurs. The first release liner is typically removed after heating, but in some cases sufficient crosslinking may occur without heating, permitting removal of the first liner while retaining a predetermined surface topography on the exposed surface of the polymeric protective layer. Advantageously, by using the above described coating process it is generally possible to produce coated layers of material that are substantially void- free (that is, free of bubbles or pinhole coating defects that are readily visible to an unaided human eye) over relatively large areas (for example, greater than 1 square meter).

In general, the effectiveness of entrapped air removal will vary with the materials and conditions used, but typically a gap of 20 mils (0.51 mm) or less (for example, less than or equal to 15 mils (0.38 mm), 10 mils (0.25 mm), 8 mils (0.20 mm), or even less than or equal to 5 mils (0.17)) may be effective. The gap may be created by any suitable means including, for example, nip roll(s), bars, platen(s), knife edge(s), or a combination thereof. Multiple nips (for example, of decreasing gap) may also be used. The reactive components should typically be fed at a sufficient rate such that the rolling bank is not depleted.

In general, the first and second release liners should have the same rate of travel, however this is not a requirement. In some embodiments, the first liner may be a continuous belt. In some embodiments, the relative position of the first and second liner (for example, as shown in Fig. 7) may be reversed.

Although a heated platen is shown in Fig. 7, any heating means may be used including, for example, infrared lamps, ovens, microwave radiation, and heated platens.

2. Metal Layer

The corrosion-resistant metallized films of the present invention further comprise a metal layer, such as exemplary metal layer 12 of exemplary corrosion-resistant metallized film 10. The metal layer may be opaque, reflective or non-reflective. In some embodiments, the metal layer provides a polished, mirror-like finish. Further, the metal layer may form a continuous or discontinuous pattern of metallic material between the polymeric protective layer and the polymeric primer layer. The metal layer may be selected from a wide range of metal-containing materials such as, for example, metals, alloys, and intermetallic compositions. The metal layer may include tin, gold, silver, aluminum, indium, nickel, iron, manganese, vanadium, cobalt, zinc, chromium, copper, titanium, and combinations thereof. Examples of combinations include, for example, stainless steel and INCONEL alloys.

The metal layer is usually formed by deposition of metal onto the above-described polymeric protective layer. The metal may be deposited using any known technique. For example, suitable deposition methods include, for example, sputtering, electroplating, ion sputtering, or vacuum deposition. In some applications, the metal is deposited using vacuum deposition methods. Suitable metal deposition methods for use in the present invention include, for example, metal deposition methods disclosed in Foundations of Vacuum Coating Technology by D. M. Mattox, published by William Andrew/Noyes (2003).

The thickness of the metal layer may vary as needed to provide a desired surface appearance. Desirably, the metal layer has a thickness that does not negatively impact the surface functionality of the outer surfaces of the above-described polymeric protective layer and the polymeric primer layer (described below) that come into contact with the metal layer.

As discussed above, the metal layer may comprise a continuous pattern (for example, a metal layer comprising a single area of metallic material) that substantially covers an outer surface of the polymeric polymer layer. An example of this embodiment is shown in Fig. 3 A, wherein exemplary metal area 30 completely covers exemplary polymeric polymer layer 37 and comprises a single continuous pattern of metallic material that forms a single area of metal. In another embodiment shown in Fig. 3B, a single continuous area of metallic material 40 may be used to form a pattern such as the letter "C" on an outer surface 38 of the polymeric polymer layer 37. In a further embodiment of the present invention, the metal layer may comprise a discontinuous pattern having two or more disconnected areas of metallic material on an outer surface of the polymeric polymer layer such as in the exemplary embodiment shown in Fig. 3C. As shown in Fig. 3C, two disconnected areas of metallic material 50 may be used to form a discontinuous pattern comprising two separate letters "C C" on an outer surface 38 of the polymeric polymer layer 37. Regardless of whether the metal layer comprises a continuous pattern or a discontinuous pattern, each area of metallic material (for example, each of exemplary metal areas 30, 40 and 50) may comprise a plurality of individual metal areas positioned adjacent to one another to form a resulting metal area, such as exemplary metal area 120 as shown in Fig. 4A. It has been discovered that, in some embodiments, enhanced corrosion resistance of a metallized film may be obtained by incorporating a metal layer containing one or more metal areas, such as exemplary metal area 120, into the metallized film. As shown in Fig. 4A, exemplary metal area 120 comprises a plurality of discontinuous metal areas 62, which form a pattern of metallic material 64. In this embodiment, although metal area 120 appears to be visually continuous, metal area 120 is discontinuous in terms of surface conductivity or resistivity.

The discontinuity of exemplary metal area 120 results in a metal layer having a surface resistivity of at least about 2 ohms/cm^, desirably, at least about 10 ohms/cm^. In one exemplary embodiment, the metal area has a surface resistivity of at least about 3, at least about 5, at least about 10, or at least about 20 ohms/cm^. In some embodiments, it is desirable for performance reasons to have as high a surface resistivity as possible while maintaining as high of an optical density that would satisfy the visual aesthetic requirements of the application.

It is believed that the discontinuity of a metal layer, such as a metal layer containing one or more areas similar to exemplary metal area 120, enables increased interaction between (i) surface functional or polar groups along an outer surface of the polymeric protective layer and (ii) surface functional or polar groups along an outer surface of the polymeric primer layer described below. Further, it is believed that the discontinuity of the metal layer enables hydrogen ion (H⁺) transport across the metal layer. Therefore, if a charge potential or hydrogen ion (H⁺) transport potential exists across the metal layer (that is, one outer surface has a positive surface functional groups or polar groups, and the other outer surface has negative surface functional groups or polar groups), hydrogen ion (H⁺) transport will occur, increasing the likelihood of corrosion of the metal layer. Consequently, in some embodiments, the metallized films of the present invention comprise a metal layer having one or more areas similar to exemplary metal area 120 sandwiched between outer surfaces of a polymeric protective layer and a polymeric primer layer, wherein both of the outer surfaces have similarly charged surface functional or polar groups thereon (for example, both surfaces have positive surface functional groups or positive polar groups thereon or therein, or both surfaces have negative surface functional groups or negative polar groups thereon or therein) in order to minimize the hydrogen ion (H⁺) transport potential across the metal layer.

One method of forming a metal area comprising a plurality of individual, adjacent metal area, such as exemplary metal area 120, comprises a metal deposition step, wherein the deposition step is terminated prior to or shortly after an onset of conductance within the metal area. Such a deposition step is illustrated in Fig. 4B, which depicts a cross- sectional view of exemplary metal area 120 shown in Fig. 4A. As shown in Fig. 4B, a plurality of discontinuous metal areas 62 extend upward from outer surface 38 of polymeric polymer layer 37. It is believed that, during a metal deposition procedure, each individual metal area 62 is assembled in a step-wise process, wherein a base metal deposit, such as exemplary base metal deposit 62 A, first attaches to outer surface 38 of polymeric polymer layer 37 at locations 39 along outer surface 38. Locations 39 may correspond to (i) a functional group on a polymeric material used in polymeric polymer layer 37, (ii) a functional group on an additive used in polymeric polymer layer 37, (iii) a surface treatment site resulting from one or more of the above-described surface treatments, or a combination of (i), (ii) and (iii). As shown in Fig. 4B, exemplary base metal deposit 62A are spaced apart from one another along outer surface 38 of polymeric polymer layer 37. As additional metal is deposited, one or more intermediate metal deposits, such as exemplary intermediate metal deposits 62B and 62C, result in individual metal areas 62 having an increased height (extending from outer surface 38) and a decrease in spacing between individual metal areas 62. At some point during the deposition step, if the metal deposition step is allowed to continue, individual metal areas 62 will merge with one another, forming a continuous metal area that is all electrically interconnected. Desirably, in some embodiments of the present invention, the metal deposition step is stopped such that outer peripheries of adjacent individual metal areas 62 have space therebetween such as shown in Fig. 4B. The primary driving force for the behavior of the metal during deposition is the high surface energy nature of the metal in relation to that of the organic- based polymeric layer. The relative surface energy difference does not enable a favorable interaction or wetting to occur between the metal and the polymeric layer thereby causing the metal initially to be deposited into discrete microscopic domains. It is believed that prior to reaching the point of electrical interconnectivity, the available surface area of metal, compared to the actual volume of metal in the coating is at or near a maximum and provides for a great amount of surface interaction between the metal coating and the polymeric protective and polymeric primer layers. It is believed that this enhanced amount of surface interaction is responsible for a greater amount of chemical interaction and stabilization at either metal surface. As shown in Fig. 4B, outer peripheries 65 of uppermost metal deposits 62D of individual metal areas 62 are positioned close to one another, but desirably have spacing therebetween. In some embodiments, outer peripheries 65 of uppermost metal deposits 62D of individual metal areas 62 may come into contact with one another and still result in a metal area having a discontinuous conductivity. As used herein, the term "discontinuous conductivity" is used to describe a metal area or metal layer typically having a surface conductivity of less than about 0.1 mhos or a surface resistivity of at least about 10 ohms/cm^, although this may vary depending on the metal used.

If a metal deposition step is allowed to continue and the resulting metal layer is too thick, in some embodiments, the positive effects of having similarly charged outer surfaces of adjacent polymeric layers (that is, the polymeric protective layer and the polymeric primer layer) appears to be overcome and corrosion resistance of the metal layer is hampered. If the metal layer becomes too thick, the surface resistivity drops. If the surface resistivity drops to a level approaching about 1.0 ohm/cm^, the positive effects of the adjacent polymeric layers disappears. It is believed that as more metal is deposited and the surface resistivity value of about 1.0 ohm/cm^ is approached, an excess of pure, unoxidized metal becomes available within the metal coating itself. This 'pure' metal is susceptible to corrosion and should oxidation start, the self-catalyzing behavior of corrosion overwhelms the positive effects of the adjacent polymeric layers, resulting in deterioration (that is, corrosion) of the metal layer. While not wishing to be bound by theory, it is believed that initial deposits of inorganic metal material are partially oxidized upon contact with the organic polymeric protective layer thereby creating a partial or half-oxide metal oxide coating. It is believed that this partial oxidation of the metal coating is at least partially responsible for the outstanding corrosion resistant characteristics of the metallized film without a loss of opacity in the metal coating. Further deposits of inorganic metal material do not undergo this partial oxidation resulting in metal coating (as oppose to metal oxide coating). Typically, the amount of metal deposited on a given surface may be measured by the optical density of the metal layer, which is a measure of transmission and is obtained by taking the negative log of transmission. Although the optical density will vary with the metal being deposited, typically, the metal layer has an optical density of less than about 2.0. For example, aluminum may have a desirable optical density lower than about 2.0, while tin may have a desirable optical density between about 2.0 and about 2.2.

3. Polymeric Primer Layer

The corrosion-resistant metallized films of the present invention also comprise at least one polymeric primer layer, such as exemplary polymeric primer layer 11 of exemplary corrosion-resistant metallized film 10. The polymeric primer layer covers an outer surface of the metal layer opposite the above-described polymeric protective layer as shown in exemplary corrosion-resistant metallized film 10 of Fig. 1. Like the polymeric protective layer, the polymeric primer layer provides the metal layer with one or more properties: scratch resistance, impact resistance, water resistance, weather resistance, solvent resistance, resistance to oxidation, and resistance to degradation by ultraviolet radiation. In most embodiments, the polymeric primer layer completely covers an outer surface of the metal layer opposite the above-described polymeric protective layer such that no portion of the metal layer is exposed.

The polymeric primer layer may comprise one or more of the above-described polymeric components and optional additives suitable for use in the polymeric protective layer, and may be made, for example, according to methods disclosed herein for making the polymeric protective layer. For example, the polymeric primer layer may be prepared using 90:10 weightweight of K-FLEX 188 and FOMREZ 55-112 polyester polyols combined with DESMODUR N3300A (balanced equivalent weight based on -OH groups) polyisocyanate, catalyzed with dibutyltin dilaurate coated between two silicone coated polyester liners using a process as shown, for example, in Fig. 7. Further, one or more outer surfaces of the polymeric primer layer may have one or more of the above-described surface treatments to alter an outer surface of the polymeric primer layer. In one exemplary embodiment, the outer surface of the polymeric primer layer adjacent the metal layer (for example, outer layer 111 of polymeric primer layer 11 shown in Fig. 1) is surface treated using one of the above-described surface treatments. In one desired embodiment of the present invention, the polymeric primer layer comprises one or more polymeric materials alone or in combination with one or more additives, wherein at least one of the polymers or additives has acidic or basic functional groups thereon. In a further desired embodiment, the polymeric primer layer comprises one or more polymeric materials alone or in combination with one or more additives, wherein (i) at least one of the polymers or additives has acidic functional groups, (ii) at least one of the polymers or additives has basic functional groups, (iii) the outer surface of the polymeric primer layer adjacent the metal layer has a corona discharge or glow discharge surface treatment, (iv) both (i) and (iii), or (v) both (ii) and (iii). In a further embodiment of the present invention, the polymeric primer layer comprises one or more thermoplastic polymeric materials so as to provide the polymeric primer layer with an outer adhesive surface opposite the metal layer. The outer adhesive surface of the polymeric primer layer may be tacky at room temperature (for example, pressure-sensitive) or after application of heat (for example, heat-activatable). Thermoplastic polymers suitable for use in the polymeric primer layer, optionally in combination with a tackifier, for providing an outer adhesive surface include, for example, polyolefms, polyurethanes, nylon, acrylics, and combinations thereof. For example, a polyamide/polyester based laminating adhesive available under the trade designation 3M THERMO-BOND 668 may be used as the polymeric primer layer. Suitable pressure-sensitive adhesives and heat-activatable adhesives for use in the polymeric primer layer include, for example, adhesives disclosed in U.S. Pat. No. RE24906 (Ulrich) and Eur. Pat. Publ. EP 0 384 598 Al (Johnson et al), the disclosures of which are incorporated herein by reference. In addition, the outer adhesive surface of the polymeric primer layer opposite the metal layer may include a surface topography to provide air-bleed capabilities to the polymeric primer layer, provide repositionability, or both.

Like the polymeric materials used to form the polymeric protective layer, the one or more polymeric materials used to form the polymeric primer layer may be cross-linked if desired. Suitable cross-linking methods include those described above with regard to the polymeric protective layer.

The polymeric primer layer may be transparent to visible radiation so that the metal layer is visible though the polymeric primer layer, that is, the polymeric primer layer allows at least about 50 percent of visible radiation to pass through the polymeric primer layer. For example, in some embodiments, the polymeric primer layer allows at least about 75 percent, at least about 80 percent, at least about 85 percent, at least about 90 percent, or at least about 95 percent of visible radiation therethrough. In some applications, the polymeric primer layer is colored yet transparent. For example, the polymeric primer layer may contain dyes and/or pigments in order to provide a color to the polymeric primer layer.

In another embodiment, pigmenting the polymeric primer layer to a point where no visible radiation is capable of passing through the polymeric primer layer will provide an enhanced appearance in the metal layer by providing an opaque backdrop. In this embodiment, incorporating a filler, such as carbon black, in the polymeric primer layer provides this feature.

The polymeric primer layer may be provided as a preformed layer such as a self- supporting film, may be cast from a solution onto the metal layer, or may be cast from a solution onto a release liner. In one exemplary embodiment, the polymeric primer layer is a self-supporting film, such as an ethylene acrylic acid (EAA) copolymer film.

If present as multiple layers, each polymeric primer layer may contribute to the overall metallized film construction. The additional polymeric primer layer(s) positioned away from the metal layer may serve as a tie layer between the polymeric primer layer adjacent the metal layer and an additional layer (for example a polyolefm layer) that has less than desirable adherence to the polymeric primer layer adjacent the metal layer. Regardless of whether the polymeric primer layer comprises a single layer or multiple layers, the polymeric primer layer adjacent the above-described metal layer has an outer surface that is adjacent the metal layer and conforms to the metal layer surface. For example, as discussed above, in some embodiments of the present invention, the outer surface of the polymeric protective layer adjacent the metal layer is a substantially flat, smooth, planar surface having very little, if any, topographical features thereon. In these embodiments, the subsequently applied metal layer has a substantially planar outer surface on which a polymeric primer layer is applied. In these embodiments, the outer surface of the polymeric primer layer adjacent the metal layer also has a substantially planar outer surface (for example, a complementary outer surface to the corresponding outer surface of the polymeric protective layer). In other embodiments of the present invention, the outer surface of the polymeric protective layer adjacent the metal layer may have a non-planar surface, such as a surface having topographical features thereon. In these embodiments, the subsequently applied metal layer is a non-planar layer. In these embodiments, the outer surface of the polymeric primer layer adjacent the metal layer has complementary non-planar outer surface that matched the topographical features of the corresponding outer surface of the polymeric protective layer.

Each polymeric primer layer typically has an average thickness of at least about 5 micrometers (μm). Depending on the given application for the corrosion-resistant metallized film, a polymeric protective layer may have an average thickness of greater than 1.0 millimeter (mm) or more. Typically, a polymeric primer layer has a thickness of at least about 10 μm, at least about 15 μm, at least about 50 μm, or at least about 100 μm. The thickness of a polymeric primer layer is usually less than about 50 μm although there is no limitation on the thickness of the polymeric primer layer. In some applications, a polymeric primer layer has a thickness less than about 40 μm, less than about 35 μm, or less than about 30 μm. For example, the thickness may be in the range of about 5 to about

100 μm, or about 10 to about 50 μm, or about 20 to about 30 μm.

In some embodiments of the present invention, the polymeric primer layer serves to isolate the metal layer from an optional adhesive layer that may be present in the overall film construction (see below). The optional adhesive layer is present for the purpose of attaching or anchoring the metallized film to a particular substrate, forming an article of manufacture. Adhesives by their very nature are capable of moving (for example, flowing) on a micro, as well as a macro scale, which enables the adhesive to interact with an adherend and wet-out against a surface of the adherend. By isolating the optional adhesive layer from the metal layer, any negative effects relating to fluid flow of an optional adhesive layer is minimized.

B. Corrosion-Resistant Metallized Film Construction Parameters The corrosion-resistant metallized films of the present invention may possess one or more of the following film construction parameters, which contribute to enhanced corrosion resistance. 1. Minimal Charge Potential Across Metal Layer

As described above, the corrosion-resistant metallized films of the present invention desirably possess surface characteristics on either side of the metal layer so as to minimize the charge potential or hydrogen ion transport potential across the metal layer. To minimize the charge potential or hydrogen ion transport potential across the metal layer, outer surfaces of the polymeric protective layer and the polymeric primer layer adjacent the metal layer comprise similarly charged functional groups or polar groups along each surface. In order to provide similarly charged functional groups or polar groups along each surface, each of the polymeric protective layer and the polymeric primer layer may independently comprise (i) at least one polymer or additive having acidic functional groups thereon, (ii) at least one polymer or additive having basic functional groups thereon, (iii) an outer surface adjacent the metal layer having a corona discharge or glow discharge surface treatment, (iv) both (i) and (iii), or (v) both (ii) and (iii).

In one desired embodiment, each of the polymeric protective layer and the polymeric primer layer independently comprise at least one polymer having acidic or basic functional groups thereon. For example, in one desired embodiment, the polymeric protective layer comprises a water-borne or solvent-based acid-functional polyurethane, while the polymeric primer layer comprises an ethylene acrylic acid (EAA) copolymer. In order to further enhance the interaction between the metal layer and the EAA copolymer, the outer surface of the EAA copolymer adjacent the metal layer is corona treated. Desirably, the metal layer comprises tin, aluminum, indium or stainless steel.

In another desired embodiment, the polymeric protective layer comprises a water- borne or solvent-based acid-functional polyurethane, while the polymeric primer layer comprises a cross-linked ethylene acrylic acid (EAA) copolymer, an ethylene vinyl acetate acid terpolymer (cross-linked or uncross-linked), or an olefm-acrylate copolymer having a corona discharge treatment.

2. Minimal Metal Layer Surface Conductivity or Maximum Metal Layer Surface Resistivity

In some embodiments, the corrosion-resistant metallized films of the present invention also comprise a metal layer having a minimal metal layer surface conductivity or a maximum metal layer surface resistivity. As discussed above, in some embodiment, it is desirable for the metal layer to have a surface resistivity of at least about 2.0 ohms/cm^, more desirably, at least about 4.0, at least about 6.0, at least about 8.0, or at least about 10.0 ohms/cm^. In one desired embodiment of the present invention, the corrosion- resistant metallized film comprises (1) polymeric protective and primer layers, each of which have similarly charged functional groups or polar groups along outer surfaces adjacent the metal layer due to each of the polymeric protective and primer layers independently comprising (i) at least one polymer or additive having acidic functional groups thereon, (ii) at least one polymer or additive having basic functional groups thereon, (iii) an outer surface adjacent the metal layer having a corona discharge or glow discharge surface treatment, (iv) both (i) and (iii), or (v) both (ii) and (iii), and (2) a metal layer sandwiched therebetween, wherein the metal layer has a surface resistivity of at least about 2.0 ohms/cm^, more desirably, at least about 10.0 ohms/cm^.

///. Articles of Manufacture Including a Corrosion-Resistant Metallized Film

The present invention is further directed to articles of manufacture, which include one or more of the above-described corrosion-resistant metallized films. The articles of manufacture of the present invention may comprise one of more of the following components in addition to the polymeric primer layer, the metal layer, and the polymeric protective layer described above. A. Adhesive Layer Articles of the present invention may include at least one of the above-described corrosion-resistant metallized films in combination with at least one adhesive layer, for example, if an outer surface of the above-described corrosion-resistant metallized film does not possess a desired degree of adhesive properties (for example, if an outer surface of the polymeric primer layer does not possess adhesive properties). Suitable adhesive layers include, for example, pressure-sensitive adhesive layers, heat-activatable adhesive layers, or a combination thereof.

Any suitable adhesive polymer may be included in the adhesive layer. The adhesive polymer may be, for example, thermoplastic, thermosetting, or a combination thereof. The adhesive surface may be tacky at room temperature (for example, pressure- sensitive) or after application of heat (for example, heat-activatable). Suitable thermoplastic adhesives include, for example, polyolefms, polyurethanes, epoxies, nylon, acrylics, and combinations thereof. Suitable thermosetting adhesives include, for example, one or two part epoxies, one or two part polyurethanes, one or two part acrylics, or combinations thereof. Suitable pressure-sensitive adhesives and heat-activatable adhesives for use in the present invention include, for example, adhesives disclosed in U.S. Pat. No. Re 24,906 (Ulrich) and Eur. Appl. Publ. EP 0 384 598 Al (Johnson et al), the disclosures of which are incorporated herein by reference. The adhesive may include a surface topography to provide air-bleed capabilities to the adhesive, provide repositionability, or both.

In an exemplary embodiment of the present invention, the article of manufacture comprises a corrosion-resistant metallized film having an adhesive layer on an outer surface of the polymeric primer layer. The article may be attached to a substrate via the adhesive layer to provide a metallic appearance to the substrate. The article may be attached to the substrate using pressure with or without heat. B. Release Liner(s) Articles of the present invention may further include at least one release liner in addition to the above-described layers of the corrosion-resistant metallized films. As described above, a first release liner may be used to provide support for the polymeric protective layer, as well as temporary protection of the polymeric protective layer prior to removal of the first release liner. If a tacky adhesive layer (for example, a pressure- sensitive adhesive layer) is present in an article of the present invention, such as the polymeric primer layer or on an outer surface of the polymeric primer layer, a second release liner may be used to provide temporary protection of the adhesive layer prior to removal of the second release liner. Such an exemplary article is shown in Fig. 5.

As shown in Fig. 5, exemplary article 20 comprises a corrosion resistant metallized film comprising polymeric primer layer 11, metal layer 12, and polymeric protective layer 13. In addition, article 20 comprises a first release liner 14 on an outer surface of polymeric protective layer 13, adhesive layer 15 on an outer surface of polymeric primer layer 11, and a second release liner 16 on an outer surface of adhesive layer 15.

The first and second release liners typically include one or more layers of materials. In some embodiments, the release liner contains a layer of paper, polyester, polyolefm (for example, polyethylene or polypropylene), or other polymeric film material. The release liner may be coated with a material to decrease the amount of adhesion between the release liner and the adhesive layer. Such coatings may include, for example, a silicone or fluorochemical material. Any commercially available release liner may be used in the present invention. As discussed above, first release liner 14 may be used to provide topographical features to the outer surface of polymeric protective layer 13. In addition, if desired, second release liner 16 may be used to provide topographical features to the outer surface of adhesive layer 15. For example, either release liner may provide a uniform (or nonuniform) pattern of valleys and/or ridges along an outer surface of polymeric protective layer 13 and/or adhesive layer 15. In other embodiments, either release liner may be used to provide an outer surface of polymeric protective layer 13 and/or adhesive layer 15 with a substantially smooth surface. As discussed above, release liners suitable for use in the present invention include, for example, release liners disclosed in U.S. Pat. Appl. Appl. Publ. No. 2004/0048024 Al (Fleming) and U.S. Pat. No. 6,984,427 (Galkiewicz), the disclosures of which are incorporated herein by reference.

Fig. 6 provides a view of article 20 of Fig. 5 attached to a given substrate after first release liner 14 and second release liner 16 have been removed. Once second release liner 16 has been removed, article 20 may be attached to substrate 18 using pressure with or without heat. Substrate 18 may be any substrate including, for example, a polymeric substrate (for example, a film, a foam, or a molded article), a glass substrate, a ceramic substrate, a metal substrate, and/or a fabric. Articles of the present invention may be useful in the preparation of various decorative items including, for example, badging for automobiles and appliances, emblems, mirror films, solar reflecting films, decorative film laminates, and/or graphics. For some uses, one or layers of article 20 may be colored. C. Thermoformable Layer(s) Articles of the present invention may include at least one of the above-described corrosion-resistant metallized films in combination with at least one thermoformable layer. One or more thermoformable layers may be positioned on an outer surface of the polymeric protective layer, the polymeric primer layer, or both. Thermoformable layers may be adhesively attached to the corrosion-resistant metallized film via the polymeric primer layer, an additional adhesive layer, or may be a component (for example, a layer) used during the formation of the polymeric protective layer, the polymeric primer layer, or both. The resulting thermoformable article comprising at least one of the above-described corrosion-resistant metallized films in combination with at least one thermoformable layer may be thermoformed to form a thermoformed article comprising a corrosion-resistant metallized film. Any conventional thermoforming technique (for example, molding) may be used to form the thermoformed article.

Thermoformable materials suitable for use in the present invention include, for example, any thermoplastic material, a thermosetting material, or a combination thereof. Thermoplastic materials such as ABS (acrylonitrile/butadiene/styrene), polycarbonate, polyester, polyurethane, polypropylene, polyethylene, acrylics, vinyls, and polyolefm blends are examples of useful thermoformable materials. In one desired embodiment, the thermoformable layer comprises an engineering thermoplastic material. Suitable engineering thermoplastic materials include, for example, polycarbonates, polyesters (for example, polybutylene terephthalate), some polyethylenes, polyamides, polysulfones, polyetheretherketones (PEEK), ABS (acrylonitrile/butadiene/styrene), SAN (styrene/acrylonitrile), polyurethanes, polyacrylics, and blends thereof.

The resulting thermoformable or thermoformed articles may be used in a variety of applications. In one exemplary embodiment, the thermoformable or thermoformed articles are used in signage, such as outdoor signage and backlit displays. Such displays typically comprise a box, which houses a light fixture, wherein the front face of the box housing is covered with a film. One such device in which the front face is covered with a transparent film is described in U.S. Pat. No. 5,224,770 (Simmons et al.), the disclosure of which is incorporated herein by reference. Another such device in which the front face is covered with a perforated film is described in U.S. Pat. No. 6,767,609 (Aeling et al.), the disclosure of which is incorporated herein by reference, wherein a perforated film is placed over a housing so that the film reflects light during the day to display an image, but may be backlit at night to illuminate an image from behind the film. The metallized films may be used similar to the transparent film in the 770 and '609 patents. The metallized films of the present invention and thermoformable or thermoformed articles made therefrom have sufficient light transmission, typically about 15-25% light transmission, so as to illuminate the sign from the backside at night or in the dark. The metallized films desirably comprise enough metal coated on the film so as to reflect light during the daytime or in a lit room to display an image (for example, a three-dimensional image that was thermoformed in the film). In one specific embodiment of the present invention, the film is imaged (for example, graphics are applied to the metallized film) on the polymeric protective layer side and is then coated with a pressure sensitive or heat activated adhesive on the polymeric primer side. The film may then be laminated to a suitable polymeric material, such as an engineering thermoplastic, and then thermoformed to a desired shape to form a cover for a housing containing a light. Alternatively, the film may be laminated to the thermoplastic and thermo formed to provide a three dimensional image. Such constructions are suitable for daylight/nighttime signage.

D. Additional Top Coat Layer(s)

Articles of the present invention may include at least one of the above-described corrosion-resistant metallized films in combination with one or more additional top coat layers provided on an outer surface of the polymeric protective layer. Suitable top coat layer materials include, for example, polymeric materials used to form the above- described polymeric protective layer. If present, the one or more additional top coat layers (i) provide some form of protection to the polymeric protective layer (for example, UV protection, scratch resistance, and/or weather resistance), (ii) acts as a tie layer between the polymeric protective layer and an additional layer that has less than desirable adherence to the polymeric protective layer (for example a polyolefm layer), or (iii) both (i) and (ii).

E. Permanently Attached Substrate(s) Articles of the present invention may include at least one of the above-described metallized films in combination with one or more permanently attached substrate layers provided on an outer surface of the polymeric protective layer, the polymeric primer layer or both. As discussed above, suitable substrate layers (for example, exemplary substrate 18 shown in Fig. 6) include, for example, a polymeric substrate (for example, a film, a foam, a molded, or article), a glass substrate, a ceramic substrate, a metal substrate, and/or a fabric. In one desired embodiment of the present invention, the substrate comprises an elastomeric substrate.

Further details concerning various polymeric primer layers, metal layers, and polymeric protective layers may be found, for example, in PCT Pat. Appln. No.

US2006/010751 (Johnson), filed March 24, 2006, the disclosure of which is incorporated herein by reference.

Objects and advantages of this invention are further illustrated by the following non- limiting 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. EXAMPLES

Example 1

An 8.5 mil thick polycarbonate film (trade designation LEXAN from GE Plastics (Pittsfield, MA)) was loaded around the cooling drum of a metal vapor coating chamber.

The cooling drum temperature was set at 15.6 ⁰C (60 ⁰F) and the chamber was pumped down to a vacuum of about 3 x 10"^ torr (4 mPas). Behind a shuttered aperture, an electron beam gun was used to heat two graphite crucibles holding tin by gradually increasing the power to a setting of 220 milliAmps. The film was pulled over the cooling drum at a speed of 3.05 mpm (10 feet/minute) past the partially opened aperture exposing the film to vaporous metal and allowing the metal to condense onto the film to form a metallized film. Conditions were adjusted to obtain a metallized film having an optical density of less than 2. The optical density was calculated by taking the negative logarithm of the light transmittance of the film and the transmittance was measured using a Macbeth model TD504 densitometer. The surface resistivity of the coated film was about 10 ohms/cm^. The surface resistivity was measured using a model 717 CONDUCTANCE MONITOR manufactured by Delcom Instruments, Inc. (Prescott, WI). The surface resistivity was recorded in ohms/cm^. Surface conductivity is the reciprocal of the resistance units and was recorded in mhos. An EAA (ethylene acrylic acid available under the trade designation PRIMACOR

3330 from Dow Chemical Company (Midland, MI)) film was extruded to a thickness of 30.5 μm (1.2 mil) thick onto a silicone release coated polyester film. The EAA film was then cross-linked by exposure to 5 Mrads of electron beam radiation at 175 kV to form a primer layer. The metal-coated polycarbonate film was then laminated to the EAA primer layer using a hot can set a 112.8 ⁰C (235 ⁰F). After cooling to room temperature the polycarbonate film was carefully peeled away from the metal layer, leaving it adhered to the EAA layer. The resulting metallized EAA layer exhibited no visible distortion of the metal layer. A 2-part polyurethane composition was prepared by mixing 6 parts of an aliphatic isocyanate (trade designation DESMODUR N3300 available from Bayer, Inc. Material Science (Toronto, Ontario, Canada)) with 6.6 parts of a polyester polyol (trade designation KFLEX 188 available from King Industries, Inc. (Norwalk, CT)), 0.55 parts of a polycaprolactone polyol (trade designation TONE POLYOL 0305 available from Dow Chemical Co. (Midland, MI)), and 2 drops of dibutyltin dilaurate. All amounts were in parts by weight. The two substrates were positioned between a slotted knife and a platen with a gap of about 0.15 mm (6 mils) between the two substrates. The composition was fed between the two substrates to form a rolling bank just in front of the slotted knife. The top substrate was a silicone release coated polyester film, and the bottom substrate was the EAA layer on the polyester film with the metallized side of the EAA film receiving the coating. The substrates were allowed to polymerize at room temperature overnight. The next day the polyester release films were removed to provide a metallized composite film having superior corrosion resistance as measured by exposing the film to a copper chloride accelerated salt spray environment. The EAA side of the film was available for further bonding to other substrates.

Example 2 A 2-part polyurethane composition was prepared by mixing 6 parts of an aliphatic isocyanate (trade designation DESMODUR N3300 available from Bayer, Inc. Material Science) with 7.6 parts of a polyester polyol (trade designation KFLEX 188 available from King Industries, Inc., Norwalk, CT), and 2 drops of dibutyltin dilaurate. All amounts were in parts by weight. Two silicone-coated polyester release liners were positioned between a slotted knife and a platen with a gap of about 0.15 mm (6 mils) between the two substrates. The composition was fed between the two release liners to form a rolling bank just in front of the slotted knife. The coating was allowed to polymerize at room temperature on a flat surface over the course of several days to form a polyurethane protective layer. The top polyester release liner was then removed from the coated film laminate and the polyurethane film surface was oxygen glow discharge treated and then metallized according to the conditions outlined in Example 1.

The crosslinked EAA film on a polyester liner, described in Example 1 , was then laminated to the metallized polyurethane surface using a hot can set a 112.8 ⁰C (235 ⁰F) to form a film composite. The polyester release liners were removed from both sides of the film composite and the film was tested for corrosion resistance. It exhibited superior corrosion resistance as measured by exposing the film to a copper chloride accelerated salt spray environment for 24 hours. Example 3

The liners were removed from the film composite of Example 2 and the film was thermoformed by positioning it with the polyurethane protective layer against a gas-porous mold so that it covered the entire surface of the mold. Vacuum was then applied to the mold which was held at a temperature of 150 ⁰F (65.6 ⁰C) and the film was then observed to elongate into the recessed areas of the mold. A two-part polyurethane backfill resin was then deposited into the recessed, thermoformed areas of the mold and an acrylic pressure- sensitive adhesive on a release coated paper liner was laminated against the backfill resin using a roller so that the excess backfill resin was removed. After the resin gelled, the vacuum was released and the thermoformed sheet was removed from the mold. The thermoformed metallized film surface was observed to be highly reflective and specular and exhibited a mirror-like appearance in all areas of the molded part.

Example 4

The polyester release film was removed from the EAA side of the film laminate of Example 2, and the EAA surface was corona treated at atmospheric pressure at a speed of 3.05 m/minute (10 feet/minute) with a power setting of 26 Hz and 250 watts. The EAA surface was then laminated to a layer of acrylic pressure-sensitive adhesive on a release liner using a nip roll heated to about 65.6 ⁰C (150 ⁰F). The acrylic adhesive had a composition of 81 parts of isooctyl acrylate and 19 parts of acrylic acid. The acrylic adhesive was then bonded to the primed surface of a layer thermoplastic heat-activatable adhesive. The heat-activatable adhesive was a thermoplastic copolymer of ethylene and propylene (trade designation PP7035E5 IMPACT COPOLYMER available from ExxonMobil Chemical Co. (Houston, TX)). The heat-activatable adhesive was primed by grafting N,N-dimethylacrylamide onto the surface using electron beam radiation according to the procedure described in EP 0 384 598 Al (Johnson et al.). The resulting laminate was then heat bonded to a wing-shaped weatherseal using a heat pressure laminator, trade designation MODEL WL-30 LAMINATOR, 3M Company (St. Paul, MN), by heating the weatherseal surface and the heat-activatable adhesive side of the metallized laminate with a stream of hot air just before the two surfaces are laminated together using the applicator wheel of the laminator. The weatherseal was formed from a dynamically vulcanized elastomer that was a blend of propylene and EPDM rubber commercially available from Advanced Elastomer Systems, LLP (Akron, OH) under the trade designation SANTOPRENE.

The resulting weatherseal had a specular appearance that could be deformed by (i) pressing on it with hand pressure or (ii) by wrapping the composite article completely around a 6.35 mm (0.25 inch) mandrel without losing its metal-like appearance and exhibited good elastic recovery. The elastic recovery is the amount of recovery that the film underwent after stretching. The stretched film was allowed to come to a final film length by laying the sample on a flat surface for at least an hour at ambient temperature (about 22 ⁰C) before measuring. Most of the recovery of the film occurred within the hour.

Example 5

A polyurethane film was prepared according to the procedure for Example 2 except that the bottom substrate was a second silicone release coated polyester film. After curing, one of the polyester films was removed. The polyurethane film on the release film was corona treated and then metallized according to the procedure for Example 1 except that the exposed polyurethane film was on the outside of the drum and the polyester film was against the coating drum. The vacuum in the coating chamber dropped to about 10^~6 torr (0.1 mPas) indicating that no volatiles were pulled out of the film in the coating chamber. The crosslinked EAA primer was laminated to the metal layer using a hot can set at 112.8 ⁰C (235 ⁰F).

Example 6

The release liner was removed from the EAA side of the polyurethane film of Example 2, and the EAA surface was laminated to a layer of 1.5 mil (0.38 micron) thick cross-linked acrylic pressure-sensitive adhesive on a release liner. The hot melt acrylic adhesive had a composition of 95.42 parts 2-methyl butyl acrylate, 3.98 parts acrylamide and 0.60 parts benzophenone that had been cross-linked by exposure to 500 mJ/cm^ of UV-A radiation from a medium pressure mercury lamp.

Sheets of 1.59 mm (0.0625 inch) thick polycarbonate (available from McMaster Carr (Elmhurst, IL)) measuring 30.5 cm (12 in) by 30.5 cm (12 in) were dried for 3 hours at 65.6 ⁰C (150 ⁰F).

The pressure-sensitive adhesive side of the metallized film was laminated to the polycarbonate sheet to form a laminated stack sample. The laminated stack samples were dried at 65.6 ⁰C (150 ⁰F) for 12 hours.

The samples were thermoformed on a LABFORM 2024 THERMOFORMER (available from Hydro-Trim Corporation (W. Nyack, NY)) with the polycarbonate side of the stack against the surface of a mold made of medium density fiberboard. The mold was rectangular having overall length and width dimensions of about 17.8 cm (7 in) by 17.8 cm (7 in) and a height of 3.8 cm (1.5 in). The opposing width edges each had an enclosed angle of 80 degrees. The length edges had an enclosed angle of 60 degrees on one edge and an enclosed angle of 75 degrees on the opposing edge. The mold had a V-shaped groove with a 90 degree enclosed angle, and positioned a distance of 8.9 cm (3.5 in) from the edge having an enclosed angle of 60 degrees. The groove divided the planar surface of the mold into a large planar surface and a small planar surface with the bottom of the groove positioned 9.6 mm (0.38 in) above the lower edge. The stack was heated on both sides for 90 seconds using an oven set at an oven temperature of 229.4 ⁰C (445 ⁰F), then vacuum formed over the mold for 9 seconds with the polycarbonate side of the stack against the mold. The resulting molded part had a mirror like finish and exhibited small amounts of extension.

Example 7

A metallized polyurethane protective film was prepared according to the procedure outlined in Example 2, except that the EAA film was not laminated to it. The hot melt adhesive of Example 6 was laminated directly onto the metal layer. The resulting adhesive coated film was laminated onto a polycarbonate sheet to form a laminated stack sample, dried, and thermo formed according to the procedure outlined in Example 6. The resulting molded part had a mirror like finish.

Examples 8-13

Thermoplastic polyurethane films that may be used as either a polymeric protective layer or polymeric primer layer, were prepared according to the procedure of Example 2, except that the compositions were prepared from a polyester polyol (trade designation KFLEX 188), a low molecular weight hydroxy terminated polybutadiene (trade designation POLY BD R20LM, available from Sartomer Co. (Exton, PA)), dicyclohexylmethane diisocyanate (trade designation DESMODUR W, available from Bayer MaterialScience LLC (Pittsburgh, PA)), and a tin catalyst. The specific formulations are reported in Table 1. Compositions in Table 1 are in parts by weight, except for the dibutyltin dilaurate which is listed in drops.

TABLE 1

Various modifications and alterations of this invention may be made by those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth herein.

Claims

We claim:

1. A corrosion-resistant metallized film comprising: a polymeric primer layer having opposite surfaces comprising a first surface and an outer surface; a metal layer adjacent the first surface of the polymeric primer layer; and a polymeric protective layer adjacent the metal layer, the protective layer having opposite surfaces comprising a second surface and an outer surface, and the second surface being in contact with the metal layer; wherein the opposite surfaces of at least one of the protective layer and the polymeric primer layer bear predetermined surface topographies, and wherein the first and second surfaces (i) have a similar surface charge, and (ii) jointly provide corrosion resistance to the metal layer.

2. The corrosion-resistant metallized film of claim 1 , wherein the predetermined surface topographies correspond to surfaces of release liners used in their formation.

3. The corrosion-resistant metallized film of claim 1, wherein at least one of the predetermined surface topographies corresponds to a surface of a mold used in its formation.

4. The corrosion-resistant metallized film of any one of claims 1 to 3, wherein the metal layer is a visually continuous layer having a discontinuous conductivity.

5. The corrosion-resistant metallized film of any one of claims 1 to 4, wherein the metal layer has a conductivity of less than about 10 mhos.

6. The corrosion-resistant metallized film of any one of any one of claims 1 to 5, wherein the metal layer has a surface resistivity of at least about 3 ohms/cm^.

7. The corrosion-resistant metallized film of any one of any one of claims 1 to 6, wherein the first and second surfaces have: (i) acidic functional groups on the first and second surfaces, (ii) basic functional groups on the first and second surfaces, (iii) a corona discharge or glow discharge surface treatment, (iv) both (i) and (iii), or (v) both (ii) and (iii).

8. The corrosion-resistant metallized film of any one of any one of claims 1 to 7, wherein the polymeric primer layer comprises at least one polymer or additive having acidic functional groups thereon, and the polymeric protective layer comprises at least one polymer or additive having acidic functional groups thereon.

9. The corrosion-resistant metallized film of any one of claims 1 to 8, wherein the polymeric protective layer comprises a polyurethane, a polymer or copolymer containing carboxyl groups thereon, a polyolefin, an ethylene/vinyl acetate/acid terpolymer, an ionomer, a polymer doped with one or more additives containing acidic or basic functional groups, or a combination thereof; and the polymeric primer layer comprises a polyurethane, a polymer or copolymer containing carboxyl groups thereon, a polyolefin, an ethylene/vinyl acetate/acid terpolymer, an ionomer, a polymer having acidic or basic functionality, a polymer doped with one or more additives containing acidic or basic functional groups, or a combination thereof.

10. The corrosion-resistant metallized film of any one of any one of claims 1 to 9, wherein the polymeric protective layer comprises an optically clear layer comprising a polyurethane or a polymer or copolymer containing carboxyl groups thereon; and the polymeric primer layer comprises a polymer having acidic functionality, an additive having acidic functionality, or a combination thereof.

11. The corrosion-resistant metallized film of any one of claims 1 to 10, wherein the polymeric primer layer comprises an ethylene acrylic acid copolymer, an ethylene/vinyl acetate/acid terpolymer, a polyurethane, or a combination thereof.

12. The corrosion-resistant metallized film of any one of claims 1 to 11, wherein the polymeric primer layer comprises an outer adhesive surface opposite the metal layer.

13. The corrosion-resistant metallized film of any one of claims 1 to 12, wherein the polymeric primer layer comprises a pressure sensitive adhesive layer.

14. The corrosion-resistant metallized film of any one of claims 1 to 13, wherein the polymeric primer layer, the polymeric protective layer, or both, comprise at least one polymer and at least one of a mercapto-functional silane or a benzotriazole.

15. The corrosion-resistant metallized film of any one of claims 1 to 14, wherein the polymeric protective layer comprises at least one polymer and at least one of a mercapto- functional silane or a benzotriazole.

16. The corrosion-resistant metallized film of any one of claims 1 to 15, wherein both the first surface and the second surface have an overall positive surface charge.

17. The corrosion-resistant metallized film of any one of claims 1 to 7, wherein both the first surface and the second surface have an overall negative surface charge.

18. The corrosion-resistant metallized film of any one of claims 1 to 17, wherein the metal layer comprises areas of metallic material, the areas being attached to bond sites along the second surface, wherein the bond sites correspond to a functional group or a treated surface area along the second surface of the polymeric protective layer.

19. The corrosion-resistant metallized film of any one of claims 1 to 18, wherein the polymeric primer layer, the polymeric protective layer, or both, are cross-linked.

20. The corrosion-resistant metallized film of any one of claims 1 to 19, wherein the polymeric primer layer, the polymeric protective layer, or both, comprise water-borne polymeric material.

21. The corrosion-resistant metallized film of any one of claims 1 to 20, wherein the polymeric protective layer comprises at least one polymer and at least one silicone wetting agent.

22. The corrosion-resistant metallized film of any one of claims 1 to 21, wherein the metal layer comprises indium, aluminum, tin, stainless steel, copper, silver, gold, chromium, nickel, alloys thereof, or a combination thereof.

23. The corrosion-resistant metallized film of any one of claims 1 to 22, wherein the metal layer has a surface resistivity of at least about 10 ohms/cm^.

24. The corrosion-resistant metallized film of any one of claims 1 to 23, further comprising at least one additional layer attached to an outer surface of the polymeric primer layer opposite the first surface, the outer surface of the protective layer opposite the second surface, or both.

25. The corrosion-resistant metallized film of any one of claims 1 to 24, further comprising at least one adhesive layer attached to an outer surface of the polymeric primer layer opposite the first surface or an outer surface of an additional layer attached to an outer surface of the polymeric primer layer opposite the first surface.

26. The corrosion-resistant metallized film of claim 25, wherein the at least one adhesive layer comprises a pressure sensitive adhesive layer.

27. The corrosion-resistant metallized film of any one of claims 1 to 26, further comprising at least one release liner on at least one outermost surface of the corrosion- resistant metallized film.

28. The corrosion-resistant metallized film of claim 27, wherein the at least one release liner provides topographical features to one or both of the outermost surfaces of the corrosion-resistant metallized film.

29. A thermoformable article comprising at least one thermoformable layer and at least one corrosion-resistant metallized film according to any one of claims 1 to 28.

30. A thermo formed article comprising the thermoformable article of claim 29 following a thermo forming step.

31. A method of forming a corrosion-resistant metallized film, the method comprising the steps of: providing a polymeric protective layer comprising a first cross-linkable composition and having a first surface with an overall positive or negative surface charge; providing a polymeric primer layer comprising a second cross-linkable composition and having a second surface with an overall surface charge similar to the first surface; and providing a metal layer in contact with, and between, the first and second surfaces, wherein at least one of the polymeric protective layer and the polymeric primer layer is made by a method comprising: forming a rolling bank of the corresponding cross- linkable composition, wherein the rolling bank contacts first and second forming substrates; passing the first and second substrates with the cross-linkable composition therebetween through a nip; and at least partially cross-linking the cross-linkable composition to provide the corresponding polymeric layer.

32. The method of claim 31 , wherein the corresponding cross-linkable composition is the first cross-linkable composition, the second forming substrate comprises a release liner, and the metal layer and the polymeric primer layer are provided by: removing the release liner from the polymeric protective layer to expose the second outer surface, depositing the metal layer over at least a portion of the second outer surface of the polymeric protective layer, and applying the second cross-linkable composition over the metal layer before at least partially cross-linking the second cross-linkable composition.

33. The method of claim 31 , wherein the corresponding cross-linkable composition is the first cross-linkable composition, the second forming substrate comprises a metallized layer on a surface of a carrier, the method further comprising: removing the carrier from the polymeric protective layer to provide a metal layer on the at least partially crosslinked polymeric protective layer, wherein the polymeric primer layer is provided by applying the second cross-linkable composition over the metal layer, after the carrier is removed, and then at least partially cross-linking the second cross-linkable composition.

34. The method of any one of claims 31 to 33, wherein the first and second forming substrates with the cross-linkable composition therebetween are passed through the nip under conditions sufficient to provide a substantially void- free layer of the cross-linkable composition.

35. The method of any one of claims 31 to 34, wherein the corresponding cross- linkable composition comprises a two-part urethane cross-linkable composition.

36. The method of any one of claims 31 to 35, wherein the corresponding cross- linkable composition is solvent-free.

37. The method of any one of claims 31 to 36, wherein the metal layer has a surface resistivity of at least about 10 ohms/cm^.

38. The method of any one of claims 31 to 37, further comprising surface treating the first surface, the second surface, or both using a corona discharge surface treatment, a flame surface treatment, or a glow discharge surface treatment.

39. The method of any one of claims 31 to 38, wherein both the first surface and the second surface have an overall positive surface charge.

40. The method of any one of claims 31 to 38, wherein both the first surface and the second surface have an overall negative surface charge.

41. The method of any one of claims 31 to 40, further comprising attaching at least one additional layer to an outer surface of the polymeric primer layer opposite the first surface, an outer surface of the polymeric protective layer opposite the second surface, or both.

42. The method of any one of claims 31 to 41 , further comprising providing topographical features to one or both outermost surfaces of the corrosion-resistant metallized film.

43. The method of any one of claims 31 to 42, wherein the polymeric primer layer, the polymeric protective layer, or both, are cross-linked.

44. The method of any one of claims 31 to 43, wherein at least one adhesive layer is attached to an outer surface of the polymeric primer layer opposite the first surface or an outer surface of an additional layer attached to an outer surface of the polymeric primer layer opposite the first surface.

45. The method of claim 44, wherein the at least one adhesive layer comprises a pressure sensitive adhesive layer.

46. The method of any one of claims 31 to 45, wherein the polymeric primer layer comprises an outer adhesive surface opposite the metal layer.

47. The method of any one of claims 31 to 46, wherein the polymeric primer layer comprises a pressure sensitive adhesive layer.

48. The method of any one of claims 31 to 47, further comprising attaching a thermoformable layer to an outer surface of the polymeric primer layer opposite the first surface to form a thermoformable article.

49. The method of any one of claims 31 to 47, further comprising thermoforming the thermoformable article.