WO2000051798A1

WO2000051798A1 - Decorative sheet material including mask layer

Info

Publication number: WO2000051798A1
Application number: PCT/US2000/003929
Authority: WO
Inventors: Scott Huffer
Original assignee: Rexam Industries Corp.
Priority date: 1999-03-01
Filing date: 2000-02-16
Publication date: 2000-09-08
Also published as: AU2881900A

Abstract

The flexible, weatherable decorative sheet material provided by the present invention comprises a thermoformable decorative paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part. The sheet material further includes an extensible mask layer releasably adhered to the outer surface of the paint film to form a protective film overlying the paint film. The mask layer comprises a polyurethane polymer, preferably a dried film of an aliphatic or aromatic polyurethane solution or water-borne dispersion. The polyurethane may be a polyester or polyether urethane. A method of contructing the decorative sheet material and a composite shaped part including the decorative sheet material are also provided.

Description

DECORATIVE SHEET MATERIAL INCLUDING MASK LAYER

FIELD OF THE INVENTION The present invention relates to sheet materials generally and more particularly relates to a sheet material suitable for use as a flexible, weatherable paint film.

BACKGROUND OF THE INVENTION Manufacturers have shown increasing interest in using paint films in lieu of spray painting for providing a decorative surface finish for parts, such as automobile body parts. This manufacturing technique reduces the environmental concerns associated with painting and has the potential to reduce manufacturing costs. An automobile body part utilizing a plastic paint film to provide a high quality base coat/clear coat automotive finish is disclosed, for example, in U.S. Patent No. 4,810,540, which is incorporated by reference herein in its entirety. In producing the part, the paint film is typically formed into a contoured three-dimensional configuration corresponding to the shape of the outer surface of the part by suitable methods, such as by thermoforming. These types of paint films have been successfully employed for surfacing parts having simple contours, which require a relatively low to moderate degree of forming of the paint film. However, various problems are presented when producing parts with more complex shapes which require much higher degrees of forming and elongation of the paint film.

Automotive manufacturers, for example, require that automotive parts have an exterior paint appearance which meets demanding performance and appearance specifications, such as weatherability, resistance to ultraviolet light degradation, high gloss, and high distinctness-of-image (DOI). Many of the automotive parts have a complex shape which requires high degrees of elongation of the paint film. Due to differences in the amount of elongation experienced by different areas of the part during the thermoforming and/or molding process, uniformity of appearance has been difficult to achieve with paint films applied prior to molding. U.S. Patent No. 5,215,826 discloses the use of a thermoformable carrier layer to protect the visual surface layers of a decorative paint film during post-forming. The thermoformable carrier layer is disclosed as comprising polyolefms, amorphous polyesters and their co-polymers, alloys and blends. However, the carrier layer disclosed therein tends to crack, craze and stretch non-uniformly during thermoforming, resulting in defects in the appearance of the paint film.

There remains a need for an improved method of providing a paint film finish to complex-shaped molded articles, such as highly contoured automobile body parts, that meets or exceeds the demanding performance and appearance specifications of part manufacturers.

SUMMARY OF THE INVENTION The present invention provides a decorative paint film that includes a formable protective layer that remains in place on the film during the molding operation. The presence of the formable protective layer prevents loss of gloss and DOI during a forming or molding process. The protective layer may be kept in place during construction of the final product, such as an automobile, in order to protect the visual appearance of the paint film finish. The protective layer may be subsequently stripped off to reveal a high quality, high gloss paint film finish. The protective layer is preferably transparent to allow visible inspection of the part for surface defects without removal of the protective layer.

The flexible, weatherable decorative sheet material provided by the present invention comprises a thermoformable decorative paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part. The sheet material further includes an extensible mask layer releasably adhered to the outer surface of the paint film to form a protective film overlying the paint film. The mask layer comprises a polyurethane polymer, preferably a dried film of an aliphatic or aromatic polyurethane solution or dispersion. The polyurethane may be a polyester or polyether urethane. In one embodiment, the extensible mask layer has a thickness of about 0.3 mil to about 3 mils and has a room temperature elongation at break of at least about 200 %. The sheet material may further include a non-extensible carrier layer, such as a polyethylene terephthalate film, releasably adhered to the extensible mask layer.

The paint film may comprise a single layer of a pigmented polymer or may comprise a base coat/clear coat film that includes a clear coat layer of a transparent weatherable polymer forming an outer surface and an underlying color coat layer of a pigmented polymer forming an inner surface of the paint film. If a single layer of pigmented polymer is used as the decorative paint film, the pigmented polymer used is preferably an alloy of a fluoropolymer composition and an acrylic polymer composition. If a clear coat/base coat configuration is used, the clear coat layer preferably comprises a transparent weatherable composition, such as an alloy of a fluoropolymer composition and an acrylic polymer composition. The decorative paint film preferably has an outer surface having a 60 degree gloss value of at least about 60.

The sheet material may further include a thermoformable backing layer bonded to the inner surface of the paint film. The thermoformable backing layer may be selected from the group consisting thermoplastic olefin, acrylonitrile-butadiene- styrene terpolymer, polypropylene, thermoplastic polyimide, polyethylene oxide, polycarbonate, polyvinyl chloride, polystyrene, styrene/polyphenylene oxide (NORYEL), polybutylene terephthalate, nylon, PETG copolyester, and mixtures, laminates and copolymers thereof. The sheet material may also include an adhesive layer affixing the paint film to the thermoformable backing layer. The adhesive layer comprises one or more layers selected from the group consisting of urethane adhesives, acrylic adhesives, acrylic adhesives with crosslinkers, chlorinated polyolefms and mixtures thereof.

The above-described decorative sheet material may be used to form a preform for in-mold surfacing of a part by thermoforming the decorative sheet material into a three-dimensional configuration. A composite shaped part may also be constructed by adhering the preform to a substrate of a thermoplastic polymer, which conforms to the three-dimensional configuration of the preform and is adhered thereto. In one embodiment, the decorative sheet material of the composite shaped part has a three- dimensional configuration in which certain areas of the sheet material have been subjected to elongation in excess of about 300% and other areas of the sheet material are substantially non-elongated and wherein the elongated areas and the non-elongated areas have a 60 degree gloss value within 10 gloss units from one another and in excess of 60.

A motor vehicle is also provided comprising a plurality of composite shaped parts wherein the extensible mask layer remains in place on the parts to protect the paint finish of the vehicle from damage during manufacture and shipment of the vehicle and is subsequently removed upon delivery of the vehicle to a customer.

A method of making a flexible, weatherable decorative sheet material is also provided. The method includes applying a coating of a polyurethane polymer onto a casting surface and drying the polymer coating to form a continuous extensible polyurethane polymer mask layer releasably adhered to the casting surface. A decorative paint film is then formed having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part. The weatherable outer surface of the paint film is releasably bonded to the exposed surface of the mask layer. The polymer coating may be dried by heating the coating to evaporate the solvent content. The decorative paint film may be formed by applying at least one coating layer to a smooth flexible casting surface, drying the coating layer on the casting surface to produce a paint film with an outer surface releasably bonded to the casting surface and with the inner surface exposed, and bonding the exposed inner surface of the paint film to a thermoformable backing layer.

The step of releasably bonding the outer surface of the paint film may include stripping the casting surface from the paint film to expose the weatherable outer surface of the paint film, bringing the exposed weatherable outer surface of the paint film into contact with the mask layer, and bonding the mask layer and the paint film together. The bonding may be accomplished by applying pressure and/or heat to the layers. The decorative sheet material constructed as described above may be thermoformed into a three-dimensional shape while the mask layer remains in place. Additionally, the thermoformed decorative sheet material may be inserted into an injection mold with the mask layer facing the mold surface. Thereafter, molten thermoplastic polymer is injected into the mold and hardening of the injected thermoplastic polymer is effected in order to bond the polymer to the decorative sheet material to form a composite shaped part. The mask layer may be thereafter stripped from the composite shaped part to expose the decorative surface of the sheet material.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

Figure 1 is a perspective view of an automobile illustrating the front fascia of the automobile having a decorative paint film applied thereto;

Figure 2 is a front view of an automobile front fascia having a decorative paint film applied thereto;

Figure 3 is a cross-sectional view of the fascia shown in Figure 2 taken along line 3-3 of Figure 2; Figure 4 is a cross-sectional view of the decorative sheet material of the present invention adhered to a substrate;

Figure 5 is a cross-sectional view of the decorative sheet material of the present invention including a clear coat and a color coat layer;

Figure 6 is a cross-sectional view of the decorative sheet material of the present invention having a single paint film layer;

Figure 7 is a schematic illustration of a process for construction of the decorative sheet material of the present invention;

Figure 8 is a schematic illustration of a process for applying the mask layer to the outer surface of a decorative paint film; Figures 9A-9D are schematic illustrations of the steps in a thermoforming process used to construct a preform; and Figures 10A-10C are schematic illustrations of steps in an injection molding process for forming a composite shaped part.

DETAILED DESCRIPTION OF THE INVENTION The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

Figure 1 illustrates an automobile 10 having a composite shaped part 12. As shown, the composite shaped part 12 is a complex, contoured three-dimensional front fascia of the automobile 10. The composite shaped part 12 has a decorative sheet material 14 applied thereto. Although not limited to such applications, the decorative sheet material 14 of the present invention is particularly advantageous for providing a decorative surface on a composite shaped part 12 of an automobile 10. However, those skilled in the art will appreciate that the present invention could be used in a variety of applications requiring a weatherable, decorative surface. Figure 2 is a front view of the composite shaped part 12 having the decorative sheet material 14 applied thereto. Figure 3 is a cross-sectional side view of the composite shaped part 12 comprising a substrate 16 having a decorative sheet material 14 applied thereto. As illustrated in Figure 3, the decorative sheet material 14 undergoes different amounts of elongation at different points along the contoured surface of the composite shaped part 12. In one embodiment, the decorative sheet material 14 of the present invention has a three-dimensional configuration in which certain areas of the sheet material have been subjected to elongation in excess of about 300%, and other areas of the sheet material are substantially non-elongated. However, the difference in gloss value between the elongated areas and the non-elongated areas should be no more than 10 gloss units with a minimum 60 degree gloss value of at least 60. The decorative sheet material 14 of the present invention is capable of maintaining a high level of gloss regardless of the amount of elongation experienced by the decorative sheet material during a thermoforming or molding process.

Figure 4 shows a greatly expanded cross-sectional view of a composite shaped part 12 comprising a decorative sheet material 14 of the present invention adhered to a substrate 16. The decorative sheet material includes a mask layer 20, a clear coat layer 22, a color coat layer 24, a primer layer 26, an adhesive layer 28, and a thermoformable backing layer 30.

The extensible mask layer 20 is designed to maintain gloss and DOI during forming processes and molding processes. Forming processes include, but are not limited to, thermoforming, cold stretching, and vacuum forming. Molding processes include, but are not limited to, injection molding, compression molding, and blow molding. The mask layer 20 also adds strength to the decorative sheet material 14 and improves process uniformity during the thermoforming process. Additionally, the extensible mask layer 20 protects the underlying layers of the decorative sheet material 14 from scratching or marring until the part is ready for display. The mask layer 20 is capable of stretching up to about 600 percent during thermoforming and has a room temperature elongation at break of at least about 200 percent. Room temperature is defined as about 15°C to about 30°C.

The mask layer 20 may be retained as the outer layer of the decorative sheet material 14 during construction of the final product, such as an automobile.

Thereafter, the mask layer 20 may be removed to reveal the underlying decorative paint film 18. For instance, the extensible mask layer 20 can be maintained as a protective layer and removed only after the vehicle has completed shipment and is ready for delivery to a customer. The extensible mask layer 20 is releasably bonded to the underlying decorative paint film 18 and may be stripped away from the underlying layers in a single piece. In a preferred embodiment, the mask layer 20 is transparent or substantially transparent to permit visual inspection of the part for surface defects without removal of the mask layer.

Additionally, the extensible mask layer 20 maintains high gloss and DOI during injection or compression molding, such as thermoplastic or thermoset compression molding, where the mold is roughened or deglossed. Roughened molds are less expensive than highly polished molds and are also functionally superior to highly polished molds because the rough mold surface enhances air removal from the mold as the mold closes. The extensible mask layer 20 protects the paint film 18 from loss of gloss or other damage caused by the mold without resorting to the use of highly polished molds.

Preferably, the extensible mask layer 20 is about 0.3 mils to about 3.0 mils in thickness. The extensible mask layer 20 comprises a polyurethane polymer. Preferably, the mask layer 20 comprises a dried film of an aliphatic or aromatic polyester or polyether polyurethane in the form of an dispersion or a solution. For example, polyurethane polymers QA 5218 and QA 5026, manufactured by Mace Adhesives and Coatings of Dudley, Massachusetts, may be used to form the mask layer 20. In one embodiment, the mask layer 20 comprises about 85 to about 99.5 weight percent polyurethane water-borne dispersion. Advantageously, a small amount of surfactant (about 0.05 to about 0.2 weight percent), such as SURFYNOL 104H manufactured by Air Products of Allentown, PA, is added to lower surface tension. The mask layer 20 composition may include additional additives designed to migrate into the clear coat layer 22 to enhance weatherability or other desirable properties of the clear coat layer or to prevent migration of additives from the clear coat into the mask layer. Migratory additives suitable for use with the present invention include, but are not limited to, hardness enhancers, release agents, ultraviolet light stabilizers, antioxidants, dyes, lubricants, surfactants, catalysts, and slip additives.

More specifically, the migratory additives useful in the present invention include benzophenone, silicones, waxes, triazoles, triazines and combinations thereof. The migratory additives are encouraged to migrate into the outer surface of the clear coat layer 22 by the heat and/or pressure present during thermoforming or molding processes. Additionally, the presence of these additives in the mask layer 20 prevents migration of additive components from the clear coat layer 22 into the mask layer.

Ultraviolet light stabilizers, such as TINUVIN 1130 and TINUVIN 292, both manufactured by Ciba Geigy of Hawthorne, NY, can be added as migratory additives in the mask layer 20 composition. Silicone additives, such as BYK333 manufactured by BYK Chemie of Wallingford, CT, can be added to lower the coefficient of friction of the clear coat layer 22. The migratory additives are generally added in amounts ranging from about 0.01 to about 2.0 weight percent, with all additives accounting for no more than about 5.0 weight percent of the mask layer 20 composition. Figures 5 and 6 are greatly expanded cross-sectional views of two embodiments of the decorative sheet material 14 of the present invention. The decorative paint film 18 may comprise a single layer 25 of a pigmented polymer, as shown in Figure 6, or may comprise multiple layers, as shown in Figures 4 and 5. If a single layer 25 of pigmented polymer is used, the polymer may be selected from the group consisting of urethane polymers, acrylic polymers, fluoropolymers, and alloys of a fluoropolymer and an acrylic polymer. FLUOREX® films manufactured by Rexam are examples of alloys of a fluoropolymer and an acrylic polymer. The single layer 25 of pigmented polymer may also include UV screeners to enhance weatherability, antioxidants, heat stabilizers, and other conventional additives. The pigmented polymer layer 25 may further include pigments, dyes, and/or flakes to enhance visual appearance.

As shown in Figures 4 and 5, the decorative paint film 18 may also comprise both a clear coat layer 22 and a color coat layer 24. The clear coat layer 22 is formed from a substantially transparent weatherable polymer composition selected to provide a film which will not significantly fade, peel, crack, or chalk when exposed to the environment for the intended life of the part 12. Additionally, the clear coat layer 22 must be formable from a two-dimensional surface to a three-dimensional surface without objectionable loss of appearance or performance properties. Advantageously, the clear coat layer 22 is selected from the group consisting of urethane polymers, acrylic polymers, fluoropolymers, and alloys or a fluoropolymer and an acrylic polymer (such as FLUOREX® films). As with the single pigmented polymer layer 25, the clear coat layer 22 may include UV screeners, antioxidants, heat stabilizers, and other conventional additives. Preferably, the clearcoat layer 22 is about 0.3 to about 3 mils in thickness. The color coat layer 24 is formed of a polymer composition containing a uniformly dispersed pigment to provide the appearance necessary for exterior automobile use. Preferably, the color coat layer 24 is selected from the group consisting of urethane polymers, acrylic polymers, fluoropolymers, and alloys or a fluoropolymer and acrylic polymer (such as FLUOREX® films). The color coat layer 24 may include pigments, dyes, and/or flakes to enhance visual appearance and improve weatherability. Preferably, the color coat layer 24 is about 0.3 to about 3 mils in thickness.

If desired, a color adjustment layer 27 may be added between the clear coat layer 22 and the color coat layer 24 to enhance visual appearance. The color adjustment layer 27 can be applied in coating form and include pigments, dyes and/or flakes or applied as a graphic design using printing methods such as gravure, rotary screen, flat bed step-and-repeat screen, ink jet, flexographic or other printing techniques.

The primer layer 26 improves adhesion between the color coat layer 24 and the adhesive layer 28. The primer layer 26 preferably comprises an acrylic polymer prepared in solution using any compatible solvent known in the art, such as toluene. In one embodiment, the primer layer 26 is prepared from a solution comprising about 65 to about 85 weight percent acrylic composition and about 5 to about 10 weight percent solvent. An acrylic polymer suitable for use in the primer layer 26 is acrylic adhesive 68070 manufactured by DuPont. The primer layer 26 may be opaque, colored or clear. Opaque is defined as less than 1 percent transmission at a wavelength of less than 400 nm. The primer layer 26 is preferably about 0.2 to about 2 mils in thickness. The primer layer 26 may be colored or opaque to protect the underlying thermoformable backing layer 30 from damage caused by UV exposure. Pigments, such as carbon black, titanium oxide, and mixtures thereof, may be added to impart color to the acrylic polymer composition used in the primer layer 26.

Additionally, additives such as UV screeners, antioxidants, and heat stabilizers may be added to the primer layer 26.

The adhesive layer 28 adheres the decorative paint film 18 to a thermoformable backing layer 30. The adhesive layer 28 comprises one or more layers selected from the group consisting of urethane adhesives, acrylic adhesives, acrylic adhesives with cross linkers, chlorinated polyolefins and mixtures thereof. Preferably, a mixture of a chlorinated polypropylene and a higher molecular weight chlorinated polyolefin is used. In one embodiment, the adhesive layer 28 is prepared from a mixture of about 5 to about 20 weight percent chlorinated polypropylene and about 1 to about 10 weight percent of a higher molecular weight chlorinated polyolefin formed in solution. A compatible solvent known in the art, such as toluene, is present in an amount of about 60 to about 80 weight percent. A chlorinated polypropylene suitable for use with the present invention is HARDLEN 13LP manufactured by Advanced Polymer. A higher molecular weight chlorinated polyolefin suitable for use with the present invention is SUPERCHLON 822S manufactured by CP/Phibrochem of Fort Lee, NJ. The adhesive layer 28 should be capable of stretching about 300 to about 600 percent. Due to the substantial elongation capability of the adhesive layer 28, the adhesive layer maintains the necessary adhesive strength to prevent delamination of the decorative paint film 18 from the thermoformable backing layer 30 over a wide temperature range. An epoxy component, such as EPON 828RS manufactured by Shell Chemical, may be added in small amounts (approximately about 0.1 to about 2.0 weight percent on a dry solids basis) as an acid scavenger. As with the primer layer 26, the adhesive layer 28 may be colored or opaque to protect the underlying thermoformable backing layer 30 from damage caused by UV exposure. Pigments, such as carbon black, titanium oxide, and mixtures thereof, may be added to impart color to the polymer composition used in the adhesive layer 28. Additives such as UV screeners, antioxidants, and heat stabilizers may be added to the adhesive layer 28. Preferably, the adhesive layer 28 is about 0.2 to about 2 mils in thickness.

The thermoformable backing layer 30 bonds the decorative paint film 18 of the decorative sheet material 14 to the substrate 16. In addition, the backing layer 30 provides bulk and/or rigidity for handling the decorative sheet material 14 as a thermoformed preform. The backing layer 30 also provides thickness to prevent glass fibers, fillers or other sources of visual roughening or "orange peel" from the substrate 16 from affecting the visual appearance of the decorative sheet material 14. The backing layer 30 must bond well with both the substrate 16 and the adhesive layer 28. The backing layer 30 may be selected from the group consisting of thermoplastic olefin, acrylonitrile-butadiene-styrene terpolymer, polypropylene, thermoplastic polyimide, polyethylene oxide, polycarbonate, polyvinyl chloride, polystyrene, styrene/polyphenylene oxide (NORYEL), polybutylene terephthalate, nylon, PETG copolyester, and mixtures, laminates and copolymers thereof, depending on the material used as the substrate 16.

Figure 7 illustrates a process for constructing the decorative sheet material 14 of the present invention. As shown, a film carrier 33 is advanced from a supply roll 38 through a series of process steps. The film carrier 33 preferably comprises a polyester casting film having a high gloss surface. The film carrier 33 is important for high gloss applications because it imparts high gloss and DOI to the decorative sheet material 14. Advantageously, the film carrier 33 comprises polyethylene terephthalate (PET) in a grade without slip additives. The film carrier 33 is about 1 to about 3 mils in thickness, preferably about 2 mils in thickness.

The film carrier 33 passes through a first coating station 40. If a single pigmented layer 25 is used as the decorative paint film 18, the pigmented layer is deposited onto the film carrier 33 using coating station 40 and the resulting film is dried by dryer 46. If a decorative paint film 18 having multiple coatings is desired, the first coating station 40 may deposit the clear coat layer 22. The clear coat layer 22 then passes through a dryer 42. Thereafter, a color coat layer 24 is deposited on the dried clear coat layer 22 using coating station 44. The color coat layer 24 is then dried using dryer 46. Optionally, the dried color coat layer 24 can be subjected to a corona treatment (not shown).

The coating stations 40 and 44 may utilize any conventional coating or casting techniques, such as reverse roll coating or slot die coating techniques. Slot die coating methods are preferred.

The dryers 42 and 46 may utilize any conventional drying technique. Preferably the dryers 42 and 46 are ovens having multiple heating zones wherein each successive heating zone operates at a progressively higher temperature. For example, an oven having four to six heating zones ranging in temperature from about 200°F to about 400°F may be used. Alternatively, dryer 42 may be eliminated from the process such that the color coat 24 is applied to the clear coat 22 while the clear coat is still wet using a "wet on wet" coating technique.

After the decorative paint film 18 is applied to the film carrier 33, the film carrier advances to a primer coating station 48, where the primer layer 26 is deposited onto the exposed layer of the decorative paint film 18. The primer layer 26 is then dried using dryer 49. Thereafter, the film carrier advances to an adhesive coating station 50, where the adhesive layer 28 is deposited onto the primer layer 26. Thereafter, the adhesive layer 28 is dried using dryer 51. The primer coating station 48 and adhesive coating station 50 may utilize any conventional coating or casting technique, such as reverse roll coating or slot die coating techniques. The dryers 49 and 51 may utilize any conventional drying technique.

A thermoformable backing layer 30 is advanced from a supply roll 52 and laminated to the adhesive-coated surface of the film carrier 33. Optionally, the backing layer 30 can be subjected to a corona treatment (not shown) prior to lamination. The resulting laminate is collected by product roll 54.

Figure 8 illustrates a process for preparing a decorative sheet material 14 having a mask layer 20. A non-extensible carrier 34 is advanced from a supply roll 58. The carrier 34 may be constructed of the same material used for the film carrier 33. Preferably, the carrier 34 comprises a polyethylene terephthalate film. The carrier 34 advances through a coating station 60, where the mask layer 20 is deposited onto a surface of the carrier. The coating station 60 may utilize any coating or casting technique known in the art, such as reverse roll coating or slot die coating techniques. Thereafter, the coated carrier 34 passes through a dryer 62 to form a dried mask layer 20. As discussed above in connection with dryers 42 and 46 used to dry the decorative paint film 18, the dryer 62 used to dry the mask layer 20 may utilize any conventional drying technique. Preferably, the dryer 62 comprises an oven with multiple heating stages. The dryer 62 evaporates the solvents present in the mask layer 20 composition.

The layers of the decorative sheet material 14 formed in the process illustrated in Figure 7 are advanced from a supply roll 56. The film carrier 33 is stripped away from the remaining layers to expose either the single pigmented layer 25 or the clear coat layer 22 of the decorative paint film 18, depending on the construction of the paint film used. The exposed outer layer of the decorative paint film 18 is laminated and releasably bonded to the mask layer 20 by nipping the two films between two rollers, 64 and 65, with or without applying heat to the layers. The resulting decorative sheet material 14 is collected by product roll 67. The non-extensible carrier 34 may be stripped away to expose the mask layer 20 before or after collection of the sheet material 14 by product roll 67.

In another embodiment, a single or multiple layer decorative paint film 18, primer layer 26, and adhesive layer 28 are coated directly onto the dried mask layer 20 rather than laminating the coated films together. The resulting multi-layer film is laminated to a backing layer 30 as described above. In a further embodiment, the mask layer is coated onto the clear coat layer 22. For example, a decorative sheet material 14 prepared according to Figure 7 could be stripped from carrier 33 so that the mask layer 20 can be coated directly onto the clear coat layer 22. The decorative sheet material 14 of the present invention can be adhered to a supporting substrate 16 in accordance with known laminating or bonding techniques. Illustrative examples of supporting substrates 16 include metal, wood, and molded polymer substrates. As explained above, exterior automobile parts are particularly suitable as the substrate 16. Suitable polymers for use as the substrate 16 include, for example, thermoplastic olefin, acrylonitrile-butadiene-styrene terpolymer, polypropylene, thermoplastic polyimide, polyethylene oxide, polycarbonate, polyvinyl chloride, polystyrene, styrene/polyphenylene oxide (NORYEL), polybutylene terephthalate, nylon, PETG copolyester, Sheet Molding Compounds (SMC), RIM urethanes, and mixtures, laminates and copolymers thereof. The decorative sheet material 14 may be applied to the substrate 16 by a variety of methods. These methods include, but are not limited to, compression molding, such as thermoplastic or thermoset compression molding, injection molding and the like. In an injection molding process, the decorative sheet material 14 may be preformed as described below or placed in the mold as a substantially flat sheet. If the sheet material 14 is placed in the mold without preforming, the heat and/or pressure of the molding process conforms the sheet material to the desired shape. Figures 9A-9D illustrate the steps in a thermoforming process. Thermoforming is often used to create a preform in a three-dimensional configuration that roughly approximates the three-dimensional configuration of the final product. The preform is then placed in a mold for in-mold surfacing of a desired substrate 16 to form the final product. Figure 9A shows heating of the decorative sheet material 14 of the present invention by heating elements 70. The heating step softens and increases the extensibility of the decorative sheet material 14 so that the sheet material will readily conform to the contoured outer surface of the mold 74. As shown in Figure 9C, the mold 74 is brought into contact with the heated decorative sheet material 14 and a vacuum is drawn to encourage conformity of the sheet material 14 to the contours of the mold 74. Thereafter, the mold 74 is removed from the decorative sheet material 14 and the sheet material is allowed to cool and harden into the three- dimensional configuration.

Figures 10A-10C illustrate steps in an in-mold surfacing process. As shown in Figure 10 A, the thermoformed decorative sheet material 14 is placed in the mold cavity 78 of an injection mold 76. The decorative sheet material is placed in the mold cavity 78 with the mask layer 20 facing the inner surface of the injection mold 76. Alternatively, the decorative sheet material 14 may be placed in the mold cavity 78 as a flat, two-dimensional insert rather than as a preform. As noted above, the mold 76 may have a roughened inner surface. The injection mold 76 is shut and a moldable polymer 82 is introduced into the mold 76 through the injection mold barrel 80. The polymer 82 bonds to the backing layer 30 and conforms to the contoured shape of the mold cavity 78. Thereafter, the moldable polymer 82 is allowed to cool and harden into a composite shaped part 12 comprising a substrate 16 bonded to a decorative sheet material 14, as shown in Figure IOC. The mask layer 20 of the decorative sheet material may be stripped from the composite shaped part 12 to expose the paint film finish when desired.

EXAMPLE 1 Ten decorative sheet material samples, five with the mask layer of the present invention releasably bonded thereto and five without the mask layer, were stretched to determine the effect of the mask layer on gloss and color of the samples. Five paint film colors were used. Each decorative sheet material sample comprised a 2 mil clear coat layer, a 2 mil color coat layer, a urethane adhesive layer and a 17 mil layer of thermoplastic polyolefin in a configuration illustrated by Figure 4 (except no primer layer was used). The color coat layer and clear coat layer both comprised

FLUOREX® copolymer manufactured by Rexam, which is a blend of about 25% acrylic resin and about 75% fluoropolymer.

Each sample was subjected to a 50% stretch. The stretching was accomplished through thermoforming. Gloss retention and Delta E were measured for each sample and compared to an unstretched standard. Gloss retention is calculated as final gloss value/initial gloss value * 100. Delta E is the overall color difference in a three dimensional color space. CieLab is the name of the color space. L.A.B. values are the tristimulus values quantifying color, wherein L is lightness/darkness, A is red/green shade, and B is blue/yellow shade. Delta E is the square root of the sum of the squares of Delta L, Delta A, and Delta B. Delta E values typically range from 0 to 100. All readings were conducted on a calibrated Greytag MacBeth spectrophotometer- integrated sphere with the following settings: D65 illuminate, 10 degree standard observer, and large area view. The results of the testing are listed in Table 1.

As shown by the data of Table 1, the samples with the mask layer retained nearly all initial gloss. In comparison, many of the samples without the mask layer exhibited sharp reductions in gloss value after stretching. The samples with the mask layer also exhibited less color change after stretching. The results suggest that the mask layer protects the paint film from loss of gloss and color change that may occur during elongation of the paint film.

Table 1

Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

THAT WHICH IS CLAIMED:

1. A flexible, weatherable decorative sheet material useful in lieu of painting for providing a decorative finish for parts, comprising: a decorative paint film, said paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part, and an extensible mask layer releasably adhered to said outer surface of said paint film to form a protective film overlying said paint film, said mask layer comprising a polyurethane polymer.

2. A sheet material according to Claim 1, wherein said mask layer has an elongation at break of at least about 200 percent.

3. A sheet material according to Claim 1, wherein said extensible mask layer comprises a dried film of an aliphatic or aromatic polyurethane solution or dispersion.

4. A sheet material according to Claim 3, wherein said mask layer comprises a dried film of a water-borne polyester urethane dispersion.

5. A sheet material according to Claim 3, wherein said mask layer comprises a dried film of a water-borne polyether urethane dispersion.

6. A sheet material according to Claim 1, wherein said extensible mask layer has a thickness of about 0.3 mil to about 3 mils.

7. A sheet material according to Claim 1, further comprising a non- extensible carrier layer releasably adhered to said extensible mask layer.

8. A sheet material according to Claim 7, wherein said non-extensible caπier layer comprises a polyethylene terephthalate film.

9. A sheet material according to Claim 1, wherein said paint film comprises a single layer of a pigmented polymer.

10. A sheet material according to Claim 1, wherein said paint film comprises a clear coat layer of a transparent weatherable polymer forming said outer surface and an underlying color coat layer of a pigmented polymer forming said inner surface of the paint film.

11. A sheet material according to Claim 10, further comprising a color adjustment layer between said clear coat layer and said color coat layer.

12. A sheet material according to Claim 1 , further comprising a thermoformable backing layer bonded to said inner surface of said paint film.

13. A sheet material according to Claim 12, wherein said thermoformable backing layer is selected from the group consisting thermoplastic olefin, acrylonitrile- butadiene-styrene terpolymer, polypropylene, thermoplastic polyimide, polyethylene oxide, polycarbonate, polyvinyl chloride, polystyrene, styrene/polyphenylene oxide, polybutylene terephthalate, nylon, PETG copolyester, and mixtures, laminates and copolymers thereof.

14. A sheet material according to Claim 13, further comprising an adhesive layer affixing said paint film to said thermoformable backing layer.

15. A sheet material according to Claim 14, wherein said adhesive layer comprises one or more layers selected from the group consisting of urethane adhesives, chlorinated polyolefms, acrylic adhesives, and mixtures thereof.

16. A preform for in-mold surfacing of a part, such as an automobile part, said preform comprising the sheet material according to Claim 1 thermoformed into a three-dimensional configuration.

17. A composite shaped part comprising the preform according to Claim 16, and a substrate of a thermoplastic polymer conforming to the three dimensional configuration of said preform and adhered thereto.

18. A composite shaped part according to claim 17, wherein said extensible mask layer is transparent to permit visual inspection of the part for surface defects without removal of said extensible mask.

19. A motor vehicle comprising a plurality of composite shaped parts according to Claim 17, and wherein said extensible mask layer remains in place on said parts to protect the paint finish of the vehicle from damage during manufacture and shipment of the vehicle and is removed upon delivery of the vehicle to a customer.

20. A flexible, weatherable decorative sheet material useful in lieu of painting for providing a decorative finish for parts, comprising: a decorative paint film, said paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part, said outer surface having a 60 degree gloss value of at least 60, and an extensible mask layer having inner and outer surfaces, the inner surface being releasably adhered to said outer surface of said paint film to form a protective film overlying said paint film, said extensible mask layer comprising an aliphatic or aromatic urethane polymer.

21. A sheet material according to Claim 20, wherein said paint film comprises a single layer of pigmented polymer composition, said polymer composition comprising an alloy of a fluoropolymer composition and an acrylic polymer composition.

22. A sheet material according to Claim 20, wherein said paint film comprises a clear coat layer of a transparent weatherable alloy of a fluoropolymer composition and an acrylic polymer composition forming said outer surface and an underlying color coat layer of a pigmented polymer composition forming said inner surface of the paint film.

23. A sheet material according to Claim 22, further comprising a color adjustment layer between said clear coat layer and said color coat layer.

24. A sheet material according to Claim 20, further comprising a thermoformable backing layer adhered to said inner surface of said paint film, and at least one adhesive layer adhering said paint film to said thermoformable backing layer.

25. A flexible, weatherable decorative sheet material useful in lieu of painting for providing a decorative finish for parts, comprising: a thermoformable decorative paint film, said paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part, said outer surface having a 60 degree gloss value of at least 65, and said paint film comprising at least one layer which contains a weatherable fluoropolymer composition, an extensible mask layer having inner and outer surfaces, the inner surface being releasably adhered to said outer surface of said paint film to form a protective film overlying said paint film, said extensible mask layer comprises a dried film of an aliphatic polyester urethane water-borne dispersion, a non-extensible polyethylene terephthalate film releasably adhered to said outer surface of said extensible mask layer, and an adhesive layer overlying said inner surface of said paint film, and a thermoformable backing layer formed of a thermoplastic olefin composition adhered to said inner surface of said paint film by said adhesive layer.

26. A composite shaped part having a decorative outer finish, comprising: a decorative sheet material comprising a decorative paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part, and a thermoformable backing layer having one surface thereof bonded to said inner surface of said paint film, a substrate adhered to the opposite surface of said thermoformable backing layer, and an extensible mask layer releasably adhered to said outer surface of said paint film to form a protective film, said mask layer comprising a polyurethane polymer.

27. A composite shaped part according to Claim 26, wherein said extensible mask layer comprises a dried film of an aliphatic or aromatic polyurethane solution or dispersion.

28. A composite shaped part according to Claim 27, wherein said mask layer comprises a dried film of a water-borne polyester urethane.

29. A composite shaped part according to Claim 26, wherein said mask layer has a thickness of about 0.3 mil to about 3 mils.

30. A motor vehicle comprising a plurality of composite shaped parts according to Claim 26, and wherein said extensible mask layer remains in place on said parts to protect the paint finish of the vehicle from damage during manufacture and shipment of the vehicle and is removed upon delivery of the vehicle to a customer.

31. A composite shaped part having a decorative outer finish and useful as an exterior automobile body part, comprising: a decorative sheet material comprising a decorative paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part, and a thermoformable backing layer having one surface thereof bonded to said inner surface of said paint film, and a substrate adhered to the opposite surface of said thermoformable backing layer, wherein said decorative sheet material has a three-dimensional configuration in which certain areas of the sheet material have been subjected to elongation in excess of about 300 percent and other areas of the sheet material are substantially non-elongated, and said certain elongated areas and said other non- elongated areas have a 60 degree gloss value within 10 gloss units of one another and in excess of 60.

32. A sheet material according to Claim 31 , wherein said paint film comprises a single layer of pigmented polymer composition, said polymer composition comprising an alloy of a fluoropolymer composition and an acrylic polymer composition.

33. A sheet material according to Claim 31 , wherein said paint film comprises a clear coat layer of a transparent weatherable alloy of a fluoropolymer composition and an acrylic polymer composition forming said outer surface and an underlying color coat layer of a pigmented polymer composition forming said inner surface of the paint film.

34. A method of making a flexible, weatherable decorative sheet material useful in lieu of painting for providing a decorative finish for parts, comprising: applying a coating of a polyurethane polymer onto a casting surface, drying the polymer coating to form a continuous extensible polyurethane polymer mask layer releasably adhered to said casting surface, forming a thermoformable decorative paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part, and releasably bonding said weatherable outer surface of said paint film to the exposed surface of said mask layer.

35. A method according to Claim 34, wherein said step of applying a coating comprises applying a coating of a water-borne aliphatic polyurethane polymer composition onto the casting surface, and said step of drying the polymer coating comprises heating the coating to evaporate the water content.

36. A method according to Claim 34, wherein said step of forming a thermoformable decorative paint film comprises applying at least one coating layer to a smooth flexible casting surface, drying said at least one coating layer on said casting surface to produce a paint film with said outer surface releasably bonded to said casting surface and with said inner surface exposed, and bonding the exposed inner surface of said paint film to a thermoformable backing layer.

37. A method according to Claim 34, wherein said step of releasably bonding said outer surface of said paint film comprises stripping said casting surface from the paint film to expose said weatherable outer surface of the paint film, bringing the exposed weatherable outer surface of the paint film into contact with said mask layer on its casting surface, bonding the mask layer and said paint film to one another, and removing the casting surface from said mask layer.

38. A method according to Claim 37, wherein said step of bonding the mask layer and said paint film to one another is performed by applying pressure and/or heat to the layers.

39. A method according to Claim 34, wherein said step of forming a thermoformable decorative paint film having an inner surface and a weatherable outer surface comprises coating a pigmented polymer composition on said casting surface and drying said coating composition to form a single layer of a pigmented polymer.

40. A method according to Claim 34, wherein said step of forming a thermoformable decorative paint film having an inner surface and a weatherable outer surface comprises applying a coating of a transparent weatherable polymer composition to said casting surface to form a clear coat layer and applying a coating of a pigmented polymer composition to said clear coat layer to form a color coat layer.

41. A method according to Claim 40, wherein said clear coat layer and said color coat layer are applied wet on wet.

42. A method according to Claim 34, further comprising the step of removing the mask layer to expose the decorative paint film.

43. A method according to Claim 34, further comprising the step of thermoforming the decorative sheet material into a three dimensional shape while said mask layer remains in place.

44. A method according to Claim 43, further comprising the steps of: inserting the thermoformed decorative sheet material into an injection mold with the mask layer facing the mold surface; injecting polymer into the mold; and effecting hardening of the injected polymer to bond the polymer to the decorative sheet material to form a composite shaped part.

45. A method according to Claim 44, further comprising the step of stripping the mask layer from the composite shaped part following said injecting and hardening steps to expose the decorative surface of the sheet material.

46. A method according to Claim 34, further comprising the steps of: inserting the decorative sheet material into a mold selected from the group consisting of compression molds, injection molds, and blow molds; and bonding the decorative sheet material to a substrate to form a composite shaped part.

47. A method of making a flexible, weatherable decorative sheet material useful in lieu of painting for providing a decorative finish for parts, comprising: applying a coating of a water-borne aliphatic polyurethane polymer onto a casting surface, drying the polymer coating to form a continuous extensible aliphatic polyurethane polymer mask layer releasably adhered to said casting surface, forming a thermoformable decorative paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part, said step of forming a paint film comprising applying at least one coating layer to a smooth flexible casting surface, drying said at least one coating layer on said casting surface to produce a paint film with said outer surface releasably bonded to said casting surface and with said inner surface exposed, and bonding the exposed inner surface of said paint film to a thermoformable backing layer, stripping said casting surface from said paint film to expose said weatherable outer surface of the paint film, bringing the exposed weatherable outer surface of the paint film into contact with said mask layer, and releasably bonding said weatherable outer surface of said paint film to the exposed surface of said mask layer.

48. A method of making a composite shaped part having a decorative outer finish and useful as an exterior automobile body part, comprising: providing a flexible, weatherable decorative sheet material comprising a decorative paint film having an inner surface and a weatherable outer surface, and an extensible mask layer releasably adhered to said outer surface of said paint film to form a protective film overlying said paint film, said mask layer comprising a polyurethane polymer, heating said decorative sheet material until it is softened, thermoforming the heated decorative sheet material into a three- dimensional configuration, allowing the thermoformed sheet material to cool and harden in the thus-produced three-dimensional configuration, inserting the thermoformed decorative sheet material into an injection mold with the mask layer facing the mold surface; injecting molten thermoplastic polymer into the mold on the side of the sheet material opposite said mask layer; effecting hardening of the injected thermoplastic polymer to bond the polymer to the decorative sheet material to form a composite shaped part, removing the thus formed composite shaped part from the injection mold, and stripping said extensible mask layer from the part.

49. A method of using a composite shaped part comprising assembling a plurality of the composite shaped parts in accordance with Claim 48 in assembled relation to form at least a portion of a motor vehicle, with said extensible mask layer left in place to protect the surface finish of the respective parts, and wherein said step of stripping the extensible mask layer is performed after assembly of the motor vehicle.

50. A method according to claim 49, wherein said step of stripping the extensible mask layer is performed only after the vehicle has completed shipment and is ready for delivery to a customer.

51. A method of making a flexible, weatherable decorative sheet material useful in lieu of painting for providing a decorative finish for parts, comprising: forming a thermoformable decorative paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part, said step of forming a paint film comprising applying at least one coating layer to a smooth flexible casting surface, drying said at least one coating layer on said casting surface to produce a paint film with said outer surface releasably bonded to said casting surface and with said inner surface exposed, bonding the exposed inner surface of said paint film to a thermoformable backing layer, and stripping said casting surface from said paint film to expose said weatherable outer surface of the paint film, applying a coating of a polyurethane polymer to the exposed outer surface of the paint film, and drying the polymer coating to form a continuous extensible polyurethane polymer mask layer releasably bonded to the outer surface of the paint film.

52. A method of making a flexible, weatherable decorative sheet material useful in lieu of painting for providing a decorative finish for parts, comprising: applying a coating of a water-borne aliphatic polyurethane polymer onto a casting surface, drying the polymer coating to form a continuous extensible aliphatic polyurethane polymer mask layer releasably adhered to said casting surface, and forming a thermoformable decorative paint film having an inner surface and a weatherable outer surface suitable for forming an exterior finish for a part, such as an automobile body part, said step of forming a paint film comprising applying at least one coating layer to the exposed surface of the mask layer, drying said at least one coating layer on said mask layer to produce a paint film with said outer surface releasably bonded to said mask layer and with said inner surface exposed, and bonding the exposed inner surface of said paint film to a thermoformable backing layer.