Patent Description:
Transfer lamination is a process by which a layer of material is applied to a substrate. Generally, transfer lamination involves bonding a transfer film having an application layer, e.g., a metallized layer, to a paper substrate, stripping the film from the substrate leaving the application layer, and then applying a coating to the layer to facilitate printing. As will be appreciated, this process typically involves multiple, separate steps.

In particular, the transfer film is coated in an initial step with a breakaway layer that allows the film to be stripped from the substrate while leaving the application layer and the breakaway layer on the substrate. After the film is coated, the application layer is applied, e.g., the film is metallized. Once the film has been metallized, an adhesive is applied and the film is then bonded to the substrate and the film/substrate is cured typically in an oven. Once removed from the oven, the film is stripped away and the substrate is coated and placed again in the oven to complete the process.

A drawback to this method is that the breakaway layer is applied to the transfer film in a step separate from the transfer lamination process. As will be apparent, each manufacturing step has associated costs and it is generally desirable to reduce such costs through a simplified process with as few manufacturing steps as reasonably necessary.

Moreover, the film used in the transfer of the application layer is typically discarded, or reused only a limited number of times, after it is stripped from the substrate due to the costs of reuse/recycling.

Used transfer film also presents disposal and recycling problems as such films are generally manufactured from polyesters such as polyethylene terephthalate, ("PET"), which are not easily recycled/remanufactured. In particular, plastic films are difficult to remanufacture in that individual characteristics of potentially remanufactured products vary considerably. Likewise, the variety of extruded resins in such films pose significant recycling challenges.

These challenges are evidenced by the fact that presently only about <NUM> % of all waste plastic film is recycled in the United States and plastic film makes up approximately <NUM> % of all landfilled municipal solid waste. In view of the above, it is desirable to have a transfer film that can be used a large number of times.

Moreover, is also generally desirable to create two usable end products, e.g., the metallized paper substrate and the used film, during a single inline lamination process, regardless of the specific end use of the film. In particular, it is desirable for used film to have multiple potential uses including, for example, use of the film as box wrap, gift wrap and the like, in addition to reuse in a subsequent lamination process. As will be appreciated, this maximizes resources and provides significant manufacturing advantages. Such benefits are unattainable with known processes.

It is also desirable to coat a transfer film for a subsequent use in which the film is embossed or printed. This provides a great deal of flexibility in the end use of a used transfer film again maximizing resources and providing a significant environmental benefit. In this context, <CIT> discloses a method of transfer lamination, which involves metallizing a first side of a film and then bonding the metallized first side to a substrate. Then, a coating is applied to a second side of the film after it has been bonded to the substrate. The bonded film and substrate are then placed in an oven. The film is then stripped from the substrate leaving metal from the film deposited on the substrate. The application of the coating is performed as an inline part of the transfer lamination process. Moreover, <CIT> discloses a strippable graphic formed by non-strippable ink, which allows for easy removing of the graphic by application of certain stripping substances. Thereby, the method includes printing an image comprising non-strippable ink onto an image-receiving substrate, printing a stratum of strippable ink onto the image, applying a first side of an adhesive layer onto the stratum, contacting a second side of the adhesive layer to the surface, and removing the image-receiving substrate to leave the image and stratum bonded to the surface. <CIT> reveals a dry ink transfer system, which allows a very thin unsupported image to be transferred to a surface. Although unsupported, the image is able to endure large amounts of friction without image distortion or damage. Further, although the method of transfer does not require heat, solvents, or high pressure, the adhesion between the image and the surface is very strong. Furthermore, <CIT> discloses a thin laminate for modifying the appearance of a surface, as well as methods and systems for modifying the appearance of a surface using the laminate. The laminate includes an indicia containing layer disposed against the lower surface of a carrier film. The laminate may further include a bonding coat or layer for attaching the laminate to a surface, at least one removable protective layer, and a release coating for facilitating the transfer of the laminate on a surface.

As such, a need exists for a method for transfer lamination which provides an ease of manufacture and cost savings currently unavailable with known processes. A need also exists for a transfer lamination process that does not require the disposal and/or recycling of a transfer film after a limited number of laminations. As discussed in detail herein, the present invention addresses these needs.

It is an object of the present invention to provide a method for transfer lamination.

It is an additional object of the present invention to provide a method for transfer lamination which provides an ease of manufacture and cost savings currently unavailable with known processes.

It is another object of the present invention to a provide method for transfer lamination in which a transfer film need not be discarded or recycled after a single lamination.

It is an additional object of the present invention to provide a method for transfer lamination which provides an ease of manufacture and cost savings through the inline coating of a transfer film for reuse while it is in use in a transfer lamination process.

It is another object of the present invention to provide a method for transfer lamination in which a transfer film does not need to be discarded or recycled after a single lamination as it is coating for reuse during a transfer lamination process.

It is an object of the present invention to provide a method for transfer lamination in which a breakaway layer may be easily applied to a transfer film.

It is another object of the present invention to provide a method for transfer lamination that provides a significant environmental benefit not available with known processes.

It is an additional object of the present invention to provide a method for transfer lamination that provides a significant environmental benefit by facilitating multiple potential reuses of a used transfer film.

It is yet another object of the present invention to provide a method for transfer lamination in which a transfer film can be coated for multiple reuses.

It is an additional object of the present invention to provide a method for transfer lamination in which a transfer film can be coated for subsequent use as box wrap.

It is yet another object of the present invention to provide a method for transfer lamination in which multiple coatings are applied to a transfer film inline during a transfer lamination process.

These objectives are solved by a method for transfer lamination as defined in claim <NUM>.

According to the invention, the method of transfer lamination involves applying a release coating to a first side of a film, applying an application layer to the first side of the film over the release coating, bonding the first side of the film to a substrate, applying a second coating to a second side of the film while the first side of the film is bonded to the substrate, and removing the film from the substrate leaving the application layer deposited on the substrate and the second coating on the second side of the film.

According to a variant that is no embodiment of the present invention, a system for transfer lamination includes a bonding station for bonding a metallized first side of a film to a substrate, a first coating station for applying a coating to a second side of the film while the film is bonded to the substrate, a curing station for curing the bonding film and substrate, and a stripping station for removing the film having the coating on the second side of the film from the substrate.

In an embodiment, the method of transfer lamination includes applying a release coating to a first side of a film, applying metallized layer to the first side of the film over the release coating, bonding the first side of the film to a substrate, applying a second coating to a second side of the film while the first side of the film is bonded to the substrate, the second coating including one of a functional coating having light-blocking, vapor-blocking or liquid-blocking properties, a textured coating, or a colored coating, curing the film and the substrate in an oven while the film is bonded to the substrate and after the second coating is applied to the second side of the film, and removing the film from the substrate leaving the metallized layer deposited on the substrate and the second coating on the second side of the film, wherein the application of the second coating is performed as an inline part of a transfer lamination process.

These and other objects, features and advantages of the present invention will become apparent in light of the detailed description of the best mode embodiment thereof, as illustrated in the accompanying drawings.

Referring to <FIG>, known processes for transfer lamination involve three general steps. The first of these steps, labeled with reference number <NUM>, is to coat the film used in the lamination. In particular, the film is coated with a breakaway layer that allows it to be removed or stripped from the substrate after the lamination has occurred. This step is performed offline, that is, it is not part of the main transfer lamination process that results in the end product. Moreover, only one side of the film is coated in this initial step.

After a side of the film has been coated with the breakaway layer, typically a polymer such as an acrylate or urethane, the film is metallized. The metallization step is also offline from the transfer lamination process and involves placing the coated film in a relatively large metallizer where metals are vacuum deposited on the coated film.

Once the coated film has been metallized, it is bonded to a substrate in a third step, represented by reference number <NUM>. In this step, the coated and metallized film is placed within a transfer lamination apparatus and the film is bonded via pressurized bonding with an adhesive to the substrate. Once bonded, the film/substrate typically are cured typically in an oven. The film is then stripped away from the substrate when it emerges from the oven leaving the metal and breakaway layer on the substrate. The metallized substrate may then be coated and cured again in the oven resulting in the end product.

As stated, the above-recited steps of coating the film with a breakaway layer, metallizing the coated film and then using the metallized, coated film in a transfer lamination process, are separate from one another. As will be readily appreciated, the greater number of steps in the manufacture of a product, the higher the associated manufacturing costs and degree of manufacturing difficulty.

Turning now to <FIG>, the apparatus <NUM> (no embodiment of the present invention) combines the steps of applying the breakaway coating to a transfer film and using the coated film in a lamination process to provide an ease of manufacture and cost reduction heretofore unknown in the art. This is accomplished through the depicted apparatus <NUM> which includes a transfer film roll <NUM> and a substrate roll <NUM> which are unwound via motors in directions A and B respectively. The transfer film <NUM> is unwound from the transfer film roll <NUM> simultaneously with substrate <NUM> as it is unwound from the substrate roll <NUM>.

The transfer film <NUM> has been coated with a breakaway layer on a first side which is to be bonded to the substrate <NUM>. The film <NUM> has also been previously metallized in a separate process. For the present discussion, the film is described as being new, i.e., no side has been previously coated with a breakaway layer. Alternatively, the film may have been previously used and inline coated as described herein.

As the substrate <NUM> is unwound and travels in direction A, an adhesive/glue is applied by an applicator <NUM>. The adhesive allows the film <NUM> and substrate <NUM> to be securely bonded. After the application of the adhesive, the film <NUM> encounters an idler roller <NUM>, which changes the path of the film and guides it toward a bonding station.

In particular, the film <NUM> and substrate <NUM> are bonded through pressure bonding which is accomplished by rollers <NUM>. Although rollers are depicted, it will be apparent that other means of bonding whether pressurized or not may be employed including the use of a pressurizing chamber instead of rollers.

Once the transfer film <NUM> has been bonded to the substrate <NUM>, a first intermediate product <NUM> is formed. This intermediate product <NUM> includes the transfer film <NUM> with the substrate <NUM> bonded to the first side of the film <NUM>. A second opposite side of the transfer film <NUM> remains uncoated.

As shown, this second, uncoated side <NUM> is then passed through a gravure coating station <NUM>. At the gravure station <NUM> a roller running in a coating bath (not shown) effectively deposits a coating onto the uncoated side <NUM> as it passes between the coating roller and a pressure roller (not shown). The gravure coating station <NUM> applies a breakaway layer <NUM> to the uncoated side <NUM> eliminating the need to coat the side <NUM> in a separate step prior to reuse in the present lamination process.

The inline coating of the uncoated side <NUM> of the film <NUM> is an important aspect. By providing a breakaway layer <NUM> to the transfer film <NUM> during the lamination process, a normally separate manufacturing step is avoided facilitating the convenient, cost-effective reuse of the film <NUM>. This simplified, streamlined process provides a cost savings and ease of manufacture that is presently unknown in the art.

Moreover, it has been found that the inline coating of intermediate product <NUM>, i.e., the film <NUM> bonded to the substrate <NUM> is superior to offline coating. In particular, it is easier to apply a breakaway layer <NUM> to a film <NUM> that is supported by a relatively rigid substrate <NUM> than it is to coat an unbonded flexible film. Applying a breakaway layer to the bonded intermediate product <NUM> results in a potentially more uniform layer as well due to this enhanced rigidity.

The simplified, cost effective manufacturing process increases the probability that the film <NUM> will be reused multiple times as the inline application of the breakaway layer is convenient and results in a potentially better, more uniform layer to be metallized.

While the present disclosure contemplates use of a gravure process, it will be appreciated that other coating methods for the inline application of the breakaway layer may be employed. Such methods may include reverse roll coating and the like as long as they can effectively apply the breakaway layer.

Moreover, the gravure coating station <NUM> can be used to apply other types of coatings depending upon the desired end use of the film. That is, the process can be used to create films for end uses other than reuse in a subsequent lamination process.

In particular, instead of applying a breakaway layer <NUM>, the gravure station can be configured to apply a coating having a specific color. For example, a permanent, solid white coating can be applied to the film facilitating its use for decorative purposes such as box wrap. As will be readily appreciated, coatings having colors other than white may be applied depending on the desired colorway or design.

It is also envisioned, that printable coatings can be applied to the film such that it can be used in a subsequent printing process. Indeed, the chemistry of such coatings may be varied depending on the type of printing to be carried out on the film. These print processes may include flexo or roto gravure, Indigo® and laser printing.

The ability to coat a transfer film for uses other than reuse in a subsequent lamination process is an important aspect. As will be appreciated, this provides flexibility, maximizes resources and provides significant manufacturing advantages. A significant environmental benefit is also achieved.

Returning now to <FIG>, once past the gravure station <NUM>, the now breakaway-coated intermediate product <NUM> encounters an idler roller <NUM>, which directs the product <NUM> toward the oven <NUM>. The intermediate product <NUM> enters a first zone <NUM> of the oven <NUM> where it is cured at a preselected temperature for a specific time period. The product <NUM> is then directed toward a stripping station <NUM> where the now pre-coated transfer film <NUM> is removed from the substrate leaving a substrate that includes the film's breakaway layer and metal layer bonded to its surface. This second intermediate product <NUM> is then directed toward a coating station <NUM> where it is coated to facilitate printing.

Once this coating has been applied, the second intermediate product <NUM> is directed toward the oven <NUM> where it is placed in a second zone to further cure. The result of this second curing process is the end product <NUM>, which is collected on a roll <NUM>.

Turning now to <FIG>, the process (no embodiment of the present invention) includes several key steps. The first of these steps is to metallize a first side of a transfer film, as indicated by reference number <NUM>. As discussed above, prior to metallization, the film has been coated with a breakaway layer. In the ensuing discussion, it is contemplated that the film to be metallized has been pre-coated with the breakaway layer. In other words, the film has been previously used and precoated in an earlier transfer lamination process. As will be appreciated, if the film is new and unused a first offline breakaway coating will be necessary.

The metallized film is then bonded to a substrate, generally paper, in a second step <NUM>. Importantly, a breakaway layer is then applied to a second side of the transfer film at step <NUM> so that, as discussed above, the film may be easily and inexpensively reused.

The bonded film/substrate is then cured at step <NUM>. This process is generally accomplished through the use of a multi-zone oven.

Once the film/substrate has been cured, the film is removed from the substrate at step <NUM>. At this point, the substrate is coated with the breakaway layer and the metal layer. The film with its pre-coated side, can then be reused beginning with metallization step <NUM>. Optionally, the substrate may be coated for printing in an additional, subsequent step and then cured again in the oven.

Moreover, it may also be possible to reuse the previously used side of the film. That is, one could strip the remaining material off the used side and recoat it with a breakaway layer. Alternatively, one could simply apply a breakaway layer over any residual material on the previously used side.

Turning now to <FIG>, an alternative embodiment of an apparatus <NUM> (no embodiment of the present invention) is depicted. This embodiment, while similar to that depicted in <FIG>, includes multiple gravure stations and ovens and facilitates the application of multiple coatings on a transfer film.

In this embodiment, the film <NUM> is adhered to the substrate <NUM> in a process much like that described above in connection with the embodiment shown in <FIG>. The film/substrate intermediate product <NUM> then passes by a first gravure station <NUM> in which a coating is applied to the film side of the intermediate product <NUM>. The film/substrate then passes through a first oven <NUM> to cure.

After emerging from the first oven <NUM>, the film side of the intermediate product is coated again at a second gravure station <NUM>. The film/substrate is then passed through a second oven <NUM>.

The second oven <NUM> and second gravure station <NUM> are an important aspect as they allow multiple coatings, also using coating mateials such as acrylic, nitrocellulose (nitro), polyvinyl, urethanes and/or PET base solutions, to be placed on the transfer film. This, in turn, allows for a wide range of potential end uses of the film. For example, the film could be coated with a breakaway coating at the first gravure station and then an embossable coating may be applied at the second gravure station <NUM>, thereby creating an embossable transfer film which could be embossed with a holographic design prior to metallization.

Referring back to <FIG>, after the film/substrate emerges from the second oven <NUM>, the transfer film, now with two coatings, is stripped and would about spool <NUM>. The metallized substrate then passes through a third gravure station <NUM> where it receives a coating that facilitates printing on the metallized surface and into a third oven <NUM> for a final cure. The metallized substrate is the wound about spool <NUM>.

In the present example, the end products are a metallized substrate which is ready for printing and a transfer film that has two coatings on it and may be used for a variety of purposes depending on the coatings.

In addition to the above, it is also possible to provide one of the gravure stations with a printing head so that the film may be printed on during the transfer lamination process. For example, the second gravure station <NUM> could be equipped with a printing head so that it can print on the transfer film after it has received a color coating at the first gravure station <NUM>. In this configuration, the second gravure station <NUM> can be used to print a corporate logo or other decorative design on a colored film.

Although the embodiment in <FIG> is depicted with three gravure stations and ovens, other configurations are possible in which more than three stations/ovens are employed depending on the desired characteristics of the end product created from the transfer film.

In sum, the afore-mentioned method and apparatus for transfer lamination which, through the inline coating of a transfer film, provides an ease of manufacture, flexibility and cost savings currently unavailable with known processes. The method and apparatus also does not necessitate the disposal and/or recycling of a transfer film after a limited number of uses and provides an easily applied and potentially superior breakaway coating.

As indicated above, in addition to, or alternative to applying a breakaway coating to the second side of a transfer film after it has been bonded to a substrate, other coatings may be applied to the exposed second side surface of the film after it has been bonded to the substrate to render the film, once stripped from the substrate as the final step in a transfer lamination process, suitable for various other end uses. For example, a coating having a colored dye or pigment may be applied to the second side surface of the film at a gravure station or other inline coating station while the film is bonded to the substrate, prior to stripping the film. In addition, decorative or other printing may be applied to the coating while the film is still adhered to the substrate such as, for example, through an inline flexographic or gravure printing process. After the transfer lamination process described above, the film, with the colored coating and any decorative printing, may then be stripped from the substrate to be used in any number of decorative applications, such as in gift wrap, flower wrap and the like.

As discussed above, the application of a coating having colored dyes or pigments to the film, as well as decorative or other printing on the coating, as an inline part of the transfer lamination process, while the first side of the film is adhered to and supported by the relatively rigid substrate, provides for improved control of coating of, and printing on, the film. In particular, the film is relatively rigidly supported and held in place without the typical deflection of films during transport within the printing press. In addition, during the application/printing process, the film is held in place, reducing the effects of doctor blade chatter or Myer bar skips within the gravure station. This allows for a more precise, metered application of coatings to the film than has heretofore been possible in the art. Moreover, where polyester films are utilized, such films may tend to stretch or shrink under application of heat, such as in ovens designed to cure the coatings. However, coatings and printing may be applied to the exposed, second side surface of the film while it is bonded to the substrate, and then exposed to heat, without the stretching or shrinkage of the film that can typically be expected when coating a stand-alone film.

In addition to colored coatings, it is further contemplated that the coating applied to the second side surface of the film while it is still bonded to the substrate may be a textured coating. According to a variant of the invention, the coating has one or more additives that mimic leather. In an embodiment, the coating may be a urethane, acrylic or polyvinylidene chloride (PVDC) coating having one or more texture-imparting additives. According to another variant of the invention, a matting agent or metal is added to the coating to impart a variety of different surface finishes such as semi-gloss, high gloss, eggshell or matte. Once applied to the second side of the film, the film may be stripped from the substrate as the final step in a conventional transfer lamination process. The film with the textured coating may then be utilized for a variety of downstream applications such as in the packaging industry. For example, the textured film may be used on cosmetic and liquor boxes and packaging and the like to provide a more striking appearance and feel for consumers.

In yet other embodiments, it is contemplated that the coating applied to the second side surface of the film while the film is still adhered to the substrate may be one of a number of functional coatings. For example, the coating may be formulated to block light, to impart a desired level of opacity. Such a film, once stripped from the substrate, can then be used in marketing applications, such as on signs, posters and the like that are typically displayed in the window fronts of stores and in shopping malls. As will be readily appreciated, the opacity of film provides a more distinct contrast from the transparent windows on which it may be used, while still providing for a line of sight into the store through the film. Other function coatings may include vapor or liquid impermeable coatings for use in various applications, such as in the food packaging industry.

In an embodiment, a release coating may first be applied to the second side surface of the film prior to applying the functional, textured coating or colored coating, so that the coating can subsequently be transferred from the second side surface of the film to another substrate, such as packaging material. Alternatively, in some embodiments, after the first side of the film is bonded to the substrate, a surface treatment may be applied to the second side of the film in order to facilitate adhesion of the second coating to the second side surface of the film. In certain embodiments, the surface treatment may include corona or plasma treatment of the second side surface to obtain better adherence of solvent and water-based coatings to the film.

As indicated above, in various embodiments, the coatings may either be utilized in connection with a release layer that is first applied, so that the coatings may be transferred from the film to another substrate, or permanently applied to the film where the film and coating are intended to be utilized as a unitary material in various downstream applications, such as in product packaging, advertising materials and the like.

Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof.

Claim 1:
A method for transfer lamination, said method comprising the steps of:
applying a release coating to a first side of a film (<NUM>);
applying an application layer to said first side of said film (<NUM>) over said release coating;
bonding said first side of said film (<NUM>) to a substrate (<NUM>);
applying a second coating to the second side of said film (<NUM>) while said first side of said film (<NUM>) is bonded to said substrate (<NUM>); and
removing said film (<NUM>) from said substrate (<NUM>) leaving said application layer deposited on said substrate (<NUM>) and said second coating on said second side of said film (<NUM>);
wherein said second coating has one or more texture-imparting additives so that said second coating mimics leather; and/or
wherein said second coating includes a matting agent or metal to impart a surface finish, including semi-gloss, high-gloss, eggshell, or matte .