Background of the Invention

Field of the Invention

The present invention relates to a metallized decorative film and a process for making it by applying the metallic film by transfer lamination. The decora¬ tive film can be used to apply decoration to a desired substrate, e.g., a motor vehicle..

Description of the Prior Art

Metallized decorative films which are suitable for exterior use and which contain a substantially trans¬ parent, plasticized film have been formed in the past by laminating the transparent film to a vacuum metallized film, e.g., a vacuum metallized polyester film, which is then overlaminated with a clear polyvinyl fluoride film which aids in protecting the polyester film from ultra¬ violet degradation. Such complex laminates are rather stiff and difficult to form into complex shapes and are subject to moisture degradation at the exposed edge of the lamination between the polyvinyl fluoride film and the polyester film.

Direct vacuum metallization of a flexible plas¬ tic film is difficult to accomplish since various

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ingredients in the film tend to "gas off" during the metallization process interfering with both the- mainten¬ ance of the vacuum and the uniformity of the metal de¬ posit. One solution to this problem has been the sug¬ gestion that a barrier layer of a long chain thermo¬ plastic polyvinyl resin containing a large number of highly polar groups be placed over the plasticized resin and that this layer be metallized and then coated with a transparent film, U.S. Patent No. 2,993,806 to E. M. Fisher et al. Another solution which has been proposed in U.S. Patent No. 3,107,198 to L. E. Amborski et al. is to treat the metallized layer with a complex compound of the Werner type.

Summary of the invention

The present invention is a metallized decora¬ tive film laminate and the process for making it. The laminate comprises: (a) a substantially transparent plas¬ tic film; (b) a thin metallic layer having one side ^" attached to one side of the plastic film by means of an adhesive layer; and (c) a pressure sensitive adhesive lay¬ er attached to the other side of the metallic layer, said adhesive layer being optionally covered on its exposed surface by a release liner. The film laminate is formed by applying the metallic layer to one side of the plastic film by transfer lamination followed by attachment of the pressure sensitive adhesive layer and, if desired, re¬ lease liner to the other side of the metallic layer.

Brief Description of th ^" Drawings

Certain preferred embodiments of the present in¬ vention are shown in greater enlarged cross-sectional view in the Drawings which accompany and form a portion of this specification wherein:

Figure 1 shows the substantially transparent

plastic film to which the metallized layer is to be attached;

Figure 2 shows the plastic film/metallic layer combination after the latter has been adhesively attached to the plastic film by transfer lamination and as the car¬ rier film in the transfer laminate responsible for the transfer lamination step is being removed;

Figure 3 shows the laminate from Figure 2 after application of a tie coat to the protective or release coating remaining from the transfer laminate used in the previous step; and

Figure 4 shows a desired end product after a re¬ lease liner and pressure sensitive adhesive have been attached to the tie coat in the laminate of Figure 3.

Description of the Preferred Embodiments

Figure 1 shows the substantially transparent plas¬ tic film 1 which may be any conventional, substantially transparent and flexible film known to persons of ordinary skill in the art of fabricating decorative pressure sensi¬ tive products. The term "substantially transparent" as used herein is intended to encompass those plastic films which are transparent enough to allow a viewer to perceive the decorative effect generated by the metallic layer in the laminate of the present invention. The thickness of the film 1 can range from about 0.05 mm. to about 0.5 mm., and the film can be a homo- or copolymer of vinyl chloride (the preferred film material) , a polyester resin, a cellu¬ lose resin, or the like. Films of this type are well known in the art and have been used heretofore in forming decora¬ tive laminates which differ in construction from the pres¬ ent laminate.

Figure 2 shows the laminate subcombination that results when a thi metallic layer 2 is adhesively attached

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to the plastic film 1. This is accomplished by transfer laminating this layer 2 to the film 1 by means of a "met¬ allized transfer laminate" which is indicated generally by the reference numeral 10 in Figure 2. Such laminates are well known but have not hitherto been used to laminate thin metallic layers to the type of substantially trans¬ parent plastic film used herein to form decorative metal¬ lized laminates useful as decorative trim, for example, on such substrates as motor vehicles, and the like. Pre¬ ferred metallized transfer laminates of this type are available under the trademark "Chromtex" from Kurz-Hast- ings, Inc. , Philadelphia, Pa.

The metallized transfer laminate comprises an adhesive layer 3 attached to a thin metallic layer 2 which is bonded to a carrier film 4, preferably by means of a protective or release coating 5. The metallized transfer laminate 10 is applied to the substantially transparent film 1 in such a way so as to adhesively bond metallic layer 2 to film 1. The carrier film 4 in the metallized transfer laminate 10 is then stripped off as shown in Fig¬ ure 2.

The carrier film 4 may be formed of a suitable flexible material capable of being coated, if. desired, by the resinous solution which constitutes the protective or release coating 5. Examples of suitable carrier films 4 are formed from polyethylene terephthalate, crystallized copolymers of polyethylene terephthalate and isophthalate, oriented polystyrene, polyvinyl flouroide, acetate coated paper, and polyolefins, such as polyethylene and polypropyl¬ ene. The carrier film 4 can have a thickness of from about 0.013 mm. to about 0.125 mm.

The protective or release coating 5 is preferably included in the metallized transfer laminate 10 since it aids άn stripping the carrier film 4 from the laminate

construction after the metallic layer 2 has been adhesive¬ ly bonded to transparent film 1. The release coating 5 may be formed by coating the carrier film 4 and is prefer¬ ably a resinous solution comprising solvents which do not adversely affect the film 4 and an organic solute not nor¬ mally compatible therewith. Some representative release coatings include the polyurethanes, silicones, phenol for¬ maldehyde solutions, solvent systems of polyesters and combinations such as methyl methacrylate, ethylene tere¬ phthalate, and ethylene isophthalate and water and organic solvent systems of polyvinyl acetate and polyvinyl chlor¬ ide. The coating used to form release layer 5 may be uni¬ formly applied by conventional coating techniques, such as, direct roller coating, reverse roller coating or by flex- ographic or rotogravure coating. The release coating 6, when dried, constitutes a layer which, while not bonded to the carrier film 4 in any chemical sense, superficially ad¬ heres to it.

The metallic layer 2 , which is attached, prefer¬ ably to the surface of release coating 5, may be formed of any metal such as gold; silver, aluminum, magnesium, titan¬ ium, nickel, zinc, copper, chromium, cobalt, selenium or the like. Metallic compounds as well as alloy s can also constitute the layer. Aluminum or an aluminum alloy are . often preferred for reasons of economy and durability. The thickness of this layer will generally range from about 500 to about 750 Angstroms to about 12,500 Angstroms. The films may be deposited on the release coating 5 by the known thermal evaporation or cathodic sputtering techniques as described in U.S. Patent No. 2,993,806.

The nature of adhesive layer 3 in the metallized transfer laminate 10 will depend upon the character of the plastic film 1 to which it will be attached. Heat activat- able adhesives that are compatible with plastic film 1 can

be used and include rubber-phenolic and polyester-isocyan- ate systems, polyurethane, and solutions of vinyl chloride/ vinyl acetate, vinyl acetate/acrylate and vinyl acetate/ maleate copolymers. Preferably, the selected adhesive will dry to a water-white clear film and remain clear even upon outdoor exposure.

Removal of the carrier film 4 from the metallized transfer laminate 10/plastic film 1 combination will leave release coating 5 exposed, if such a coating is present. When such a coating is in the transfer laminate 10 for its release properties, it may be necessary to apply a resin¬ ous tie coat 6 (as shown in Figure 3) to the exposed sur¬ face of release coating 5 in order to provide a site for later secure attachment of a layer of pressure sensitive adhesive 7 and, if desired, a release liner 8 (as shown in Figure 4) . Tie coats which are compatible with and thus have good anchorage to both release coating 5 and the de¬ sired pressure sensitive adhesive 7 will adequately serve the intended purpose. The tie coat should also possess good cohesive, strength so that it will not be a site of internal failure in the final laminate. Polyurethane tie coats having the above-described compatibilities and co¬ hesive strength are one representative class of tie coats that may be used.

Figure 4 in the Drawings shows a preferred and finished laminate of the present invention wherein a layer of pressure sensitive adhesive 7 and a release liner 8 have been applied to the exposed surface of the tie coat 6.

The pressure sensitive adhesive 7 which is used in the present laminate may also be any of the pressure sensitive adhesives which are known and conventionally used in the art. As for the applicable tacky, pressure sensi¬ tive adhesives which may be utilized in the product of this invention, they may be based upon any elastomeric material

such as: (1) natural rubber; (2) synthetic rubbers in¬ cluding, for example, styrene-butadiene copolymers, poly- . isobutylene, butadiene-acrylonitrile copolymers, poly- chloroprene, and polyisoprene; (3) acrylic copolymers con¬ taining at least 50 percent, by weight, of a C -Cι ₂ alkyl acrylate ester, i.e., an alkyl acrylate ester wherein the alkyl group contains from 4 to 12 carbon atoms, together with a hardening comonomer, for example, vinyl acetate, styrene, methyl methacrylate, methyl acrylate, ethyl acryl¬ ate, ethyl methacrylate and vinyl chloride; and (4) poly¬ mers of alkyl vinyl ethers such, for example, as polymethyl vinyl ether and polyethyl vinyl ether. Acrylic pressure sensitive adhesives are most preferred since they have the best balance of adhesive and cohesive properties for the present laminate. The thickness of the adhesive layer 7 will generally be in the range of from about 0.013 m. to about 0.05 mm. •

If the laminate of the present invention is to be manufactured at one location and used at another loca¬ tion, a release liner 8 is preferably affixed to the side of the pressure sensitive layer 7 which is furthest re¬ moved from film 1. The release liner 8 may be any of the release liners known to persons of ordinary skill in the art of making pressure sensitive products including remov¬ able, water soluble protective coatings, and the like. One preferred liner material is silicone coated release paper having a thickness of from about 0.05 mm. to about 0.3 mm. Of course, if the film/adhesive composite is to be manu¬ factured and applied to a desired substrate at the same manufacturing location, a release liner may not be needed.

A preferred process for affixing the combination containing the film 1 and the pressure sensitive adhesive 7 and release liner 8 comprises transfer coating. In such a process, ^' a fluid solution of the adhesive 7 is applied to

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the release liner 8, and the resulting composite is heated to dry the adhesive layer 7. The adhesive side of this adhesive/liner laminate is then laminated to the exposed surface of the protective layer 6 at a ^' conven¬ tional lamination nip to form the product shown in Figure 4.

When the laminate of the present invention is to be used, the adhesive layer 7 is brought into contact with a desired substrate and, when properly positioned, pressure is applied to securely affix it to a desired sub¬ strate, e.g., a motor vehicle.

The Example which follows illustrates certain preferred embodiments of the present invention.

EXAMPLE

This Example illustrates how one product of the present invention was made under laboratory conditions.

A transparent polyvinyl chloride (PVC) exterior grade film having a thickness of about 0.07 mm. was lam¬ inated to a release coated polyester film which had been metallized followed by coating of the metallized surface with a clear, light stable, heat activatable adhesive ("No. 9353 Chro tex Smooth Gold 78 with 840 adhesive", available from Kurz-Hastings. Inc., Philadelphia, Pa.). This metallized transfer laminate was 0.02 mm. in thick¬ ness and had its adhesive side laminated to the matte or dull side of the PVC film by passing both films over a series of heated drums. This raised the temperature of the heat activatable adhesive to about 135°C. for proper activation and formation of a satisfactory bond of the metallized transfer laminate to the PVC film. The poly¬ ester film was then removed from the transfer laminate leaving a PVC film/adhesive/metal layer/release coated intermediate structure.

In order to satisfactorily bond pressure sensi¬ tive adhesive and release paper to the release coated side of the structure resulting from the previous steps, approx¬ imately 0.005 mm. of a polyurethane polymer tie coat was applied to the release coating. The polyurethane polymer that was used was a fuϋy^reacted polyurethane polymer sup¬ plied as a solution in toluene and isopropanol (available as "Milloxane LS-516" from Millmaster Onyx) . After the tie coat layer was allowed to dry by being heated at 70°C. for 30 sec, a layer of about 0.025 mm..of pressure sensitive adhesive was applied to the tie coat layer by means of a conventional transfer technique. The adhesive that was used herein was a high molecular weight thermoplastic

acrylic terpolymer, which is available as "Durotak 80- 1053" from National Starch and Chemical Corp. In such a technique, the wet adhesive is coated directly onto re¬ lease paper at a thickness of about 0.076 mm. followed by evaporation of the solvent by heating at 10.0°C. for 2 minutes. This is followed by lamination of the dried ad¬ hesive to the tie coat layer by passing the adhesive/re¬ lease liner laminate and the PVC containing laminate through a laminating nip.

After lamination, a high level of adhesion was exhibited between the layer of pressure sensitive adhes¬ ive and tie coat. The resulting laminate is useful as a metallized film for such end uses as automobile trim.

The above Example shows a preferred embodiment of the present invention and should not be construed in a limiting sense. The scope of protection that is sought is given in the claims which follow.