Laminates and method of manufacture thereof

Abstract

A laminate material suitable for producing graphic signs and labels comprises a substrate 3 having a water-soluble film 1 on a first side and an adhesive 2 on a second side. When the laminate material

Description

Application Title: Laminates and method of manufacture thereof. Description. This invention relates to self-adhesive laminates and method of manufacture thereof, The invention has particular, but not exclusive, application to laminates suitable for labelling or decoration or graphic signs or the like. Most laminates used for labelling or decoration or graphic signs have an adhesive backing and a release liner which protects the adhesive during, for example, cutting, printing and / or handling. The liner typically has a release coating, such as silicone, which allows the liner to be removed from the adhesive prior to application of the laminate to a surface. Such laminates are typically made in roll form which are shipped, printed and die cut before being applied to an article to be labelled or decorated, or converted into a graphic sign. The release liner serves to protect the adhesive throughout the process and is removed, either by the printer or at the point of application, and in each case, becomes a waste. Release liners often end up in landfill because the release coating creates obstacles during recycling processes. The present invention anticipates an innovative way of creating such laminate materials that eliminates the use of a release liner with a release coating on one or both sides, or without a release coating on either side. The invention seeks to provide a laminate material in which the adhesive has a water- soluble protective coating that is easily removed and preferably may be recycled. In one aspect, the present invention provides a self-adhesive laminate material from which labels and graphic signs can be produced comprising a substrate having a first side and a second side, a water-soluble film on the first side and an adhesive on the second side, wherein when the laminate material is rolled up, the water-soluble film on the first side is transferred to the adhesive on the second side such that the water-soluble film protects the adhesive. The affinity of the pressure sensitive adhesive for the water-soluble film is greater than that of the water-soluble film for the print ready coating and transfer to the adhesive thereby occurs protecting the adhesive and preventing the product from blocking during storage in a roll. The substrate may comprise any suitable material such as a paper or polymeric material. The water-soluble film may comprise any suitable material such as a water-soluble or water-dispersible polymer. Suitable polymers include but are not limited to those based on poly-vinyl alcohol. The adhesive may comprise any suitable adhesive such as a pressure sensitive adhesive. Suitable pressure sensitive adhesives include but are not limited to a water based pressure sensitive adhesive, a solvent-based pressure sensitive adhesive or a hotmelt pressure sensitive adhesive . The water-soluble film may be formed by applying a coating of an aqueous solution or dispersion of the water-soluble polymer that, once dried, produces a film. The film may have a thickness of less than 5 microns, more preferably a thickness of 2 - 3 microns. By comparison, a typical release liner has a thickness greater than 19 microns, sometimes up to 140 microns in the case of graphic arts laminates. As a result, the reduced thickness of the water-soluble film of the present invention means that more material may be carried on a roll of given diameter which brings logistics and storage benefits. The adhesive may be coated on the second side of the substrate either simultaneously, (i.e. at the same time as the water-soluble coating is applied to the first side), or sequentially (i.e. later) during the same pass, or in a separate pass. Where the adhesive and the water-soluble coating are applied during the same pass, this is known as dual coating. It is important to underline the difference in this application between the terms water- soluble coating and water-soluble film. Once a coating has been applied to a substrate and subsequently dried, it becomes a film on the surface of the substrate. However, the term film may also be used to describe a substrate made from the coated material in a previous process. In the present invention, the thickness of the water-soluble coating after drying is only a few microns and hence the resulting film cannot support itself. In the present invention, by casting the water-soluble coating upon a flat substrate, it is possible to create a water-soluble film of a few microns thickness which is supported by the substrate until it enters into contact with the adhesive which occurs as the material is rolled up. The resulting bond between the adhesive and the water-soluble film is sufficient to remove the water-soluble film from the substrate and protect the adhesive thereafter. When a water-soluble coating is applied directly to an adhesive, it not only covers the peaks in the adhesive but also fills the troughs. In contrast, in the present invention, when the water-soluble film is produced by applying the water-soluble coating to a flat surface and then dried, and subsequently transferred to protect the adhesive, it covers the peaks in the adhesive but does not fill the troughs. The importance of this distinction is two-fold: not only is less water-soluble polymer required to protect the adhesive thereby offering material savings but its subsequent removal during activation of the adhesive will be 2 facilitated as no water-soluble polymer will need to be removed from the troughs in the adhesive allowing a skimming or scraping tool to be more effectively employed. In one embodiment, the substrate has a print ready coating sandwiched between the polymeric or paper material of the substrate and the water-soluble film i.e. the water soluble coating is applied on top of the print ready coating. The print ready coating may provide an enhanced key for the water soluble film created when the water soluble coating has dried. The print ready coating may comprise any suitable material designed to enhance the key of an ink or coating to the substrate. Suitable materials for the print ready coating include but are not limited to those based upon acrylic or urethane polymers. Print ready coatings are designed to enhance the adhesion of print to the substrate and it could be expected that the same enhancement would occur between the water-soluble film and the print ready coating but we have found that this is not the case with certain water-soluble polymers including those based upon poly-vinyl alcohol. We have found that not only are such water-soluble films easily removable from the print ready coating but no traces of the water-soluble film remain to interfere with subsequent printing. When the laminate material of the present invention is unwound at a printer or a label applicator or for use in graphic arts, the water-soluble film is no longer present on the first side of the substrate leaving the first side of the substrate free of any residual contamination by the water-soluble film so that the first side remains ready to receive inks or decorative coatings. The water-soluble film can be removed from the adhesive prior to applying the laminate material to an object by applying water as a spray or mist to the surface of the water- soluble film in order to soften the water soluble film and then by rubbing the softened film to facilitate the removal of the now partially solubilised film from the surface of the adhesive. The laminate material, now with an exposed adhesive, can be cut and applied to an object. The removed water-soluble film may present as a gel that can be readily recycled. In another aspect, the present invention provides a method of producing a self-adhesive laminate material by providing a substrate having a first side and a second side, a water- soluble film on the first side and an adhesive on the second side, and rolling up the laminate such that the water-soluble film comes into contact with and transfers to the adhesive to produce the self-adhesive laminate material in which the adhesive is protected by the water-soluble film. 3 The substrate may comprise any suitable material such as paper or a polymeric material such as substrates of thickness typically between 13 and 100 microns made from polypropylene, polyester, polyethylene, or poly-vinyl chloride. The water-soluble film may comprise any suitable material such as those films based substantially upon poly-vinyl alcohol polymers. The adhesive may comprise any suitable adhesive such as a water-based pressure sensitive adhesive, a solvent-based pressure sensitive adhesive or a hotmelt pressure sensitive adhesive. The water-soluble film may be removed to expose the adhesive by applying water as a spray or mist to the surface of the water-soluble film to soften the water-soluble film and then by rubbing the softened film to facilitate the removal of the now partially solubilised film from the surface of the adhesive. The laminate material, now with an exposed adhesive, can be cut and applied to an object. The removed water-soluble fim may present as a gel that can be readily recycled. The substrate may include a print ready coating on the first side and an adhesive ready coating on the second side. The water-soluble film may have a thickness of less than 5 microns, preferably a thickness of 2 - 3 microns. The water-soluble film may be applied as a coating of an aqueous solution or dispersion of the water-soluble polymer, for example by known coating techniques, and dried before the laminate material is rolled up. The adhesive, may be coated on the second side of the substrate either simultaneously (i.e. at the same time) as the water soluble coating is applied to the first side, or sequentially (i.e. later) during the same pass or in a separate pass. Where the adhesive and the water-soluble coating are applied during the same pass, this is known as dual coating. In another aspect, the present invention provides a self-adhesive material from which labels and graphic signs can be produced comprising a proprietary coating providing an enhanced key sandwiched between a polymeric or paper substrate and a water-soluble film wherein the second face of the polymeric or paper substrate is coated with an adhesive such that when the material is rolled up, the water-soluble film transfers to and thereby protects the adhesive. 4 The proprietary coating providing an enhanced key may be a print receptive coating. The print surface of the proprietary coating providing an enhanced key may be uncontaminated by traces of the water-soluble film after its transfer to the adhesive The dry weight of water-soluble coating required to protect the adhesive without blocking may be less than that required for direct coating without blocking. In another aspect the present invention provides a laminate material comprising a substrate, a coating of print receptive material upon a first side of the substrate and a water-soluble film upon the coating of print receptive material. Preferably the laminate material further comprises an adhesive on a second side of the material such that when the laminate material is rolled up, the water-soluble film on the first side is transferred to the adhesive on the second side such that the water-soluble film protects the adhesive. By way of illustration of the present invention only, figures 1 thru 6 are shown. In all six figures, a polymeric or paper substrate is marked (3), a pressure sensitive adhesive is marked (2) and a water-soluble protective film is marked (1). In figures 5 and 6, a print ready coating is marked (4). Figures 1 and 2 illustrate a product not according to the invention. In Figure 1, the water-soluble film 1 is created by direct application of a water-soluble coating upon a pressure-sensitive adhesive (2) which has previously been coated upon one side of the polymeric or paper substrate (3). The water soluble coating is applied as an aqueous solution or dispersion of a water soluble polymer such as polyvinyl alcohol and dried to form the film 1. As can be seen, the water-soluble coating covers the peaks and fills the troughs created by irregularities in the surface of the adhesive. Figure 2 illustrates the product of figure 1 after it has been rolled up and unwound. No change has occurred to the product i.e. the film 1 remains attached to the adhesive. Figures 3 and 4 illustrate an embodiment of a product according to the invention. In Figure 3, the water-soluble coating forming the film 1 is applied as an aqueous solution or dispersion of water-soluble polymer upon an upper face of the polymeric or paper substrate (3) and dried to form the film 1. A pressure sensitive adhesive (2) is applied to the lower face of the polymeric or paper substrate either in the same pass or in a separate pass. 5 Figure 4 illustrates the product of figure 3 after it has been rolled up and unwound. As shown, the water-soluble film (1) has transferred from the substrate (3) to the adhesive (2) which as a result, is now protected from blocking in the roll. As can be seen, the film attaches to the peaks but does not fill the troughs created by irregularities in the surface of the adhesive. Figures 5 and 6 illustrate another embodiment of a product according to the invention. In Figure 5, the water-soluble coating forming the film (1) is applied as an aqueous solution or dispersion of water-soluble polymer upon an upper face of the polymeric or paper substrate (3) which has already been coated with the print ready coating (4) and dried to form the film (1) with the print ready coating (4) sandwiched between the substrate (3) and film (1). A pressure sensitive adhesive (2) is applied to the lower face of the polymeric or paper substrate. Figure 6 illustrates the product of figure 5 after it has been rolled up and unwound. The water-soluble film (1) has transferred from the print ready coating (4) to the pressure sensitive adhesive (2) which as a result, is now protected from blocking in the roll. As can be seen, the film (1) attaches to the peaks but does not fill the troughs created by the irregularities in the surface of the adhesive. As will be apparent from the foregoing, the present invention provides a laminate material and a method by which the laminate can be produced and processed into an adhesive label or graphic sign without the use of a release liner during its manufacture and without creating the need to dispose of a release liner following application of a label or graphic sign. In addition, by forming the water soluble film on the opposite side of the substrate to which the adhesive is applied and subsequently transferring the film to the adhesive, the water soluble material of the film only adheres to the peaks and does not fill the troughs created by irregularities in the surface of the adhesive. As a result, the thickness of the water- soluble film may be reduced, in turn reducing the amount of water-soluble material used to form the water-soluble film and thereby facilitating subsequent removal of the film to expose the adhesive for attaching the product to the surface of an object. Moreover, the present invention provides an adhesive laminate and a means of manufacturing an adhesive laminate without the use of a release liner wherein the pressure sensitive adhesive is protected by a water-soluble film having such a reduced thickness that it is unable to support itself. 6

Claims

1. A method of producing a self-adhesive laminate material by providing a substrate having a first side and a second side, a print receptive coating sandwiched between the substrate and a water-soluble film on the first side and a pressure sensitive adhesive on the second side, and rolling up the material such that the water-soluble film comes into contact with and transfers to the adhesive to produce an adhesive-backed laminate material wherein the adhesive is protected by the water-soluble film.

2. A method according to claim 1 wherein the water-soluble film is formed by coating the print receptive coating with an aqueous solution of water-soluble polymer which is dried to produce the film.3, A method according to claim 2 wherein the dry weight of water-soluble coating required to protect the adhesive without blocking is less that than that required for direct coating of a water-soluble coating upon the adhesive without blocking4. A method according to any one of the preceding claims wherein the water-soluble film comprises a thickness of less than 5 microns.

5. A method according to claim 4 wherein the water-soluble film comprises a thickness of between 2 and 3 microns.

6. A method according to any one of the preceding claims wherein the water-soluble film comprises substantially polyvinyl alcohol.

7. A method according to any one of the preceding claims wherein the substrate is polymeric.

8. A method according to claim 7 wherein the substrate is selected from the group comprising polypropylene, polyester, polyethylene and polyvinyl chloride polymers.9 A method according to any one of claims 1 to 6 wherein the substrate is paper.

10. A method according to any preceding claim wherein the substrate has a thickness between 13 and 100 microns.11, A method according to any preceding claim wherein the print receptive coating is selected from the group comprising acrylic and urethane polymers.

12. A material comprising a substrate having a first side and a second side, a print receptive coating on a first side of the substrate and a water-soluble film upon theprint receptive coating wherein the water-soluble film is supported by the substrate until it enters into contact with a pressure-sensitive adhesive applied to the second side of the substrate upon the material being wound into a roll, and wherein the adhesion of the water-soluble film to the pressure sensitive adhesive is greater5 than the adhesion of the water-soluble film to the print receptive coating such that when the material is unwound, the water-soluble film transfers to and remains attached to the pressure sensitive adhesive.

13. A material according to claims 12 wherein the print receptive coating comprises a10 material selected from the group comprising acrylic and urethan polymers.

14. A material according to claim 12 wherein the substrate is polymeric.

15. A material according to claim 12 wherein the substrate is paper.1516. A material according to any one of claims 12 to 15 wherein a print surface of the print receptive coating is uncontaminated by traces of water-soluble film after the transfer of the water-soluble film.M 20 17. A material according to any one of claims 12 to 16 wherein the water-soluble filmCM comprises a thickness less than 5 microns.CM__ 518. A material according to claim 17 wherein the water-soluble film comprises athickness of between 2 and 3 microns.0)2519. A material according to any one of claims 12 to 18 wherein the water-soluble film comprises substantially poly-vinyl alcohol.

20. A material according to any one of claims 12 to 19 wherein the water-soluble film30 adheres to peaks and does not fill troughs created by irregularities in the surface of the adhesive.

21. A self-adhesive graphic sign made from the material according to any one of claims 12 to 20.3522. A self-adhesive label made from the material according to any one of claims 12 to 20.

23. A self-adhesive graphic sign made from the material produced by the method 40 according to any one of claims 1 to 11.

24. A self-adhesive label made from the material produced by the method according to any one of claims 1 to 11.

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