AU2005287152A1 - Labels and labeling process - Google Patents

Description

WO 2006/033925 PCT/US2005/032784 TITLE: LABELS AND LABELING PROCESS This application claims the benefit of provisional application Serial No. 60/610,816 filed on September 17, 2004, which is hereby incorporated herein by reference in its entirety. TECHNICAL FIELD OF THE INVENTION This invention relates to labels, and more particularly to polymeric film labels, and to a process of printing polymeric film labels. BACKGROUND OF THE INVENTION Clear polymeric labels are increasingly desired for many applications, since they provide a no-label look to decorated glass and plastic containers. Paper labels block the visibility of the container and/or the contents in the container. Clear labels enhance the visual aesthetics of the container, and therefore the product, and are growing much faster than paper labels in the package decoration market as consumer product companies are continuously trying to upgrade the appearance of their products. In the bottled beverage industry, particularly the bottled beer industry, the standards to which the labels are held can be quite stringent. For example, the labeled bottles must withstand the pasteurization process. The labels must be abrasion resistant because of the demands of the bottling, packing, shipping and storage processes. The labels must also survive being immersed in ice water for extended periods of time. Typically, polymer labels used for beer bottles are reverse printed on the underside of the clear polymeric facestock and adhesive is applied to the print layer. Upon application of the label to the bottle, the print layer is positioned between the polymeric label and the bottle surface. Alternatively, the polymeric label is printed on its upper surface and then overlaminated with a second, clear polymeric film. The print layer is then sandwiched between the two polymeric films. Gravure printing is often used to print the high definition graphics and designs onto the polymeric film. In gravure printing, the gravure ink is deposited in image wells in the flat surface of a gravure plate, and the 1 WO 2006/033925 PCT/US2005/032784 deposited ink image is then transferred to the label facestock. Since gravure printing typically is carried out at high speeds, the gravure ink typically contains volatile organic solvents that dissolve the ink binder components and must be rapidly removed during the drying process. In order to gravure print ink onto polymeric film facestock, particularly biaxially oriented polypropylene (BOPP), a primer layer is fi rst coated onto the BOPP surface. The primer layer improves the adhesion of the gravure ink to the BOPP film. However the addition of the primer layer increases the manufacturing costs and time of the labeling process. Accordingly, it would be desirable to product labels, in particular, polymeric film labels having a high quality print layer ard the durability to withstand the demands of the manufacturing process at red uced cost. SUMMARY OF THE INVENTION In one aspect, this invention relates to a label that comprises (a) a unprimed polypropylene facestock having an upper surface and a lower surface; (b) a pressure sensitive adhesive layer in contact with the lower surface of the facestock; (c) a solvent-based ink layer printed on the upper surface of the facestock; and (d) an overprint varnish layer overlying the ink layer. In another aspect, the invention relates to a method for making printed labels comprising (a) providing an unprimed biaxially oriented polypropylene facestock having an upper surface and a lower surface; (b) corona treating the upper surface of the facestock; (c) printing a solvent based ink directly onto the upper surface of the facestock to form a print layer; (d) drying the solvent based ink; (e) coating the print layer with an overprint coating; and (f) applying an adhesive to the lower surface of the facestock. The solvent based ink may be printed by gravure printing. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic illustration of a side view of a label construction of the present invention. 2 WO 2006/033925 PCT/US2005/032784 DESCRIPTION OF THE INVENTION The term "transparent" when referring to one or more layers of the label means any material beneath such layers can be seen through such layers. In reference to the use of the "transparent" or "clear" labels applied to clear containers, such as beer bottles, the bottle and the beer within the bottle are visible through the label. The term "clear" when referring to one or more layers of the label or to the label itself means the opacity of the layers or label is less than about 5%, and the layers or the label has a haze of less than about 10%. Opacity is measured in accordance with TAPPI Test T425 os, and haze is measured in accordance with ASTM Test Method D-1003. In one embodiment, the label that comprises (a) an unprimed polypropylene facestock having an upper surface and a lower surface; (b) an adhesive layer in contact with the lower surface of the facestock; (c) a print layer comprising a solvent-based ink printed on the upper surface of the facestock; and (d) an overprint layer overlying the ink layer. In FIG. 1, label 10 comprises a polymer facestock 11 having an upper surface and a lower surface, a print layer 12 having an upper surface and a lower surface wherein the lower surface of the print layer 12 is in contact with the upper surface of the facestock 11, an overprint layer 13 in contact with the upper surface of the print layer 12, and an adhesive layer 14 that is in contact with the lower surface of the facestock. The polymer facestock 11 in a first embodiment comprises a biaxially oriented polypropylene (BOPP) film. BOPP films useful in the labels of the present invention are available commercially from a variety of sources, particularly Fasson Roll Materials, a division of Avery Dennison Corp., Painesville, Ohio. Other sources include AMTOPP, a division of Interplast Group LTD, Livingston, New Jersey; Exxon Mobil Chemical Co., Macdon, New York; AET Films, New Castle, Delaware; UCB Films Inc., Smyrna, Georgia; and Vifan USA, a division of Vibac, Montreal, Canada. In one embodiment, the thickness of the BOPP film is in the range of about 20 microns to about 50 microns, or about 25 microns, or about 30 microns, or about 45 microns or about 50 microns. 3 WO 2006/033925 PCT/US2005/032784 The BOPP facestock film is not topcoated or coated with a primer prior to printing of the solvent-based ink. The solvent-based ink is printed directly onto the BOPP film. The surface energy of the BOPP facestock can be enhanced by treatments such as corona discharge, flame, or plasma to provide a surface with improved adhesion to subsequently applied layers, including the ink applied to the upper surface. Procedures for corona treating and flame treating are well known to those skilled in the art. In one embodiment, the BOPP facestock is corona discharge treated on press on the upper surface of the facestock. The print layer 12 is in contact with the upper surface of the BOPP facestock. The print layer may be an ink or graphics layer, and the print layer may be a mono-colored or multi-colored print layer depending on the printed message and/or the intended pictorial design. These include variable imprinted data such as serial numbers, bar codes, trademarks, etc. The thickness of the print layer is typically in the range of about 0.5 to about 10 microns, and in one embodiment, about 1 to about 5 microns, and in another embodiment about 1 to about 3 microns. The inks used in the print layer include commercially available solvent-based inks. The print layer is formed by depositing by printing an ink composition comprising a resin, a suitable pigment or dye and one or more suitable volatile solvents onto the upper surface of the BOPP facestock. After application of the ink composition, the volatile solvent component(s) of the ink composition evaporate(s), leaving only the non-volatile ink components to form the print layer. The print layer may be formed by gravure printing. The solvent-based ink composition comprises at least one solvent soluble resin, a colorant and an organic solvent. Non-limiting examples of the resin include polyurethanes, polyolefins, polyacryls, polymethacryls, polyamides, polyvinyl acetates, polyvinyl alcohols, polyvinyl ethers, polyacrylonitriles, polystyrenes, polyvinyl pyrrolidones, polyvinyl chlorides, polyvinyl fluoride, polyvinyl butyral, poly(alkylene oxides), cellulosic polymers including nitrocellulose, and copolymers of one or more monomers including olefins, (meth) acrylates, vinyl acetates, allyl acetates, vinyl chlorides, acrylonitriles, N-vinyl pyrrolidones, N-vinyl oxazolidones, vinyl ethers and other allylic and vinylic monomers, and mixtures of two or more thereof. 4 WO 2006/033925 PCT/US2005/032784 The colorants may include soluble dyes, pigments or mixtures thereof. The classes of dyes include acid dyes, natural dyes, direct dyes either cationic or anionic direct dyes, basic dyes and reactive dyes. The pigments may be any conventional organic or inorganic pigment. Useful organic solvents for printing inks include, but are not limited to ester solvents such as ethyl acetate, propyl acetate, isopropyl acetate, etc., alcohols such as methanol, ethanol, n-propanol, isopropanol and solvents such as an ester/alcohol mixture. The solvent-based ink composition may also contain one or more additives to adjust flow, surface tension, and gloss of a cured ink. Such additives typically comprise polymeric dispersants, surface active agents, fillers, waxes, or a combination thereof. The additives may function as leveling agents, optical brighteners, plasticizers, drying promoters, viscosity regulators, extenders, anti-fouling agents, anti-blocking agents, anti-slip agents, anti-static agents, wetting agents, dispersants, defrothers, deareators, adhesion promoters, anti-wear agents and/or rub-resistance agents, or other additives may be used to provide a specific function. Solvent-based inks are commercially available. Examples of such inks include those available from Sicpa under the tradename BARGOFOR. Pigments for solvent based printing inks are commercially available from Sun Chemical under the trade names SUNBRITE*, SUNFAST* and FASTOGEN*. Nitrocellulose based inks are available from Siegwerk as the MRH 23 series of inks. Solvent based inks available from XSYS Print Solutions include nitrocellulose based, polyamide based, polyvinyl butyral based, and polyvinyl chloride based inks. In one embodiment, the printing ink comprises reflective metal flakes that have been embossed. Printing inks containing embossed metallic leafing pigments are described in US Patent 5,672,410, which is incorporated by reference herein. In one embodiment, embossed fine particulate thin metallic flakes having high levels of brightness and color intensity are produced by providing a release surface on a carrier, embossing the release surface with a diffraction grating pattern having an angular ruling pattern greater than 450, metalizing the embossed release surface with a thin reflective metal film, removing the metal film from the release surface to form a solvent dispersion 5 WO 2006/033925 PCT/US2005/032784 of embossed metal flakes that have replicated the diffraction grating pattern, and controlling the particle size of the flakes contained in the dispersion to maintain the embossed flakes contained therein at a D50 particle size at or above 75 microns. The embossed flakes can be used to produce printing inks having extremely high brightness characterized as an optically apparent glitter or sparkle effect in combination with high color intensity or chromaticity. The embossed metal flakes can be combined with an acrylic and/or nitrocellulosic resin binder to produce a printing ink. Printing ink containing embossed metallic flakes is commercially available from Eckart GmbH. A transparent overprint layer 13 overlies the print layer. The protective overprint layer provides desirable properties to the label before and after the label is affixed to the container. The presence of the transparent overprint layer may, in some embodiments, provide additional properties such as antistatic properties, stiffness and/or weatherability, and the overprint layer may protect the print layer from, e.g., weather, sun, abrasion, moisture, water, etc. The transparent overprint layer can enhance the properties of the underlying print layer to provide a glossier and richer image. The protective overprint layer may also be designed to be abrasion resistant, radiation resistant (e.g., UV), chemically resistant, thermally resistant thereby protecting the label and, particularly the print layer from degradation from such causes. The overprint layer may also contain antistatic agents, or anti-block agents to provide fro easier handling when the labels are being applied to containers at high speeds. The overprint layer may also be selected to provide labels useful on containers subjected to subsequent washing/rinsing, filling and pasteurization, or liquid immersion (e.g., ice bath) without displaying adverse consequences such as label lifting or hazing. The overprint layer may be applied to the print layer from a solution. The thickness of the overprint layer is generally in the range of about 0.5 to about 5 mils, and in one embodiment about 1 to about 3 mils. In one embodiment, the overprint layer comprises a two component, solvent based, chlorine-free, high-gloss varnish commercially available from Sicpa (Switzerland) under the tradename BARGOFLEX L726-2. A hardener, CFA 4488 also from Sicpa, is used with the two component varnish. In another embodiment, the overprint layer comprises a single component 6 WO 2006/033925 PCT/US2005/032784 varnish. UV flexo cationic varnishes are commercially available from Sicpa, Sun Chemical (New Jersey) and XSYS Print Solutions. These alternative combinations may also be used on non-topcoated BOPP for beer labels. The adhesive layer 14 of the label comprises a pressure sensitive adhesive (PSA). A description of useful pressure sensitive adhesives may be found in Encyclopedia of Polymer Science and Engineering, Vol. 13. Wiley Interscience Publishers (New York, 1988). Additional description of useful PSAs may be found in Polymer Science and Technology, Vol. 1, Interscience Publishers (New York, 1964). Conventional PSAs, including acrylic-based PSAs, rubber-based PSAs and silicone-based PSAs are useful. The PSA may be a solvent based or may be a water based adhesive. In one embodiment, the printed labels are produced by (a) providing an unprimed biaxially oriented polypropylene facestock having an upper surface and a lower surface; (b) corona treating the upper surface of the facestock; (c) printing a solvent based ink directly onto the upper surface of the facestock to form a print layer; (d) drying the solvent based ink; (e) coating the print layer with an overprint coating; and (f) applying an adhesive to the lower surface of the facestock. The solvent base ink may be printed directly onto the facestock by gravure printing. The labels of the present invention have particular utility in the beverage industry, wherein the beverage containers are subjected to relatively rough handling. The processes the labeled containers have to withstand may include filling, packing, shipping and storage. The label may also have to withstand pasteurization and/or recycling operations. The labels may be applied to glass, polymeric and metal containers. Clear BOPP may be used to achieve a "no look" label where the presence of the label is not very apparent to the consumer. EXAMPLES The following are examples of labels prepared in accordance with the present invention, and the application of the labels to glass bottles. Label graphics are printed using a solvent based ink onto the surface of 2 mil thick, clear BOPP films from Fasson, Painesville, Ohio identified as BEV/MDO A, BEV/MDO B and BEV/MDO C. 7 WO 2006/033925 PCT/US2005/032784 None of the films used are primed or topcoated. The print surface of the each film is corona treated immediately prior to application of the ink. Ink is gravure printed onto the surface of the films using a solvent based ink available from Sicpa (Switzerland) under the trade name BARGOFOR. Multiple colors of ink are used. In one embodiment, the gravure cylinder used to apply the inks has cell depths of 40 microns to about 90 microns. Depending on the particular ink used and other printing concerns, the gravure cylinder may have cell depths in the range of about 5 microns to about 120 microns, or more. After application of the inks, the printed film is heated to evaporate the ink solvent. A two-component overprint varnish is then applied over the print layer and allowed to dry. As understood by those skilled in the art, multiple layers of ink may be deposited in order to achieve the desired print effect, color and/or quality. The inks deposited may be the same or different. The labels produced pass a pasteurization test in which the labels are placed in an oven for 50 minutes at room temperature (about 250C), heated to 700C and then cooled to room temperature. The labels produced also pass an abrasion test designed to simulate the bottling process wherein labeled bottles are manually rubbed against each other for 2 minutes under dry conditions, 2 minutes under wet conditions and another 2 minutes under dry conditions. While the invention has been explained in relation to its preferred embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, it is to be under stood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims. 8

Claims (14)

1. A label comprising: a unprimed polypropylene facestock having an upper surface and a lower surface; a pressure sensitive adhesive layer in contact with the lower surface of the facestock; a solvent-based ink layer printed on the upper surface of the facestock; and an overprint coating overlying the ink layer.

2. The label of claim 1 wherein the upper surface of the facestock is corona treated.

3. The label of claim 1 wherein the overprint coating comprises a two component varnish.

4. The label of claim 1 wherein the overprint coating comprises a cationic varnish.

5. The label of claim 1 wherein the label is a beer bottle label.

6. The label of claim 1 wherein the overprint coating is the exterior layer of the label.

7. The label of claim 1 wherein the ink comprises embossed metallic flakes.

8. A method for making printed labels comprising: providing an unprimed biaxially oriented polypropylene facestock having an upper surface and a lower surface; corona treating the upper surface of the facestock; printing a solvent based ink directly onto the upper surface of the facestock to form a print layer; drying the solvent based ink; 9 WO 2006/033925 PCT/US2005/032784 coating the print layer with an overprint coating; and applying an adhesive to the lower surface of the facestock.

9. The method of claim 8 wherein the overprint coating comprises a two component varnish.

10. The method of claim 8 wherein the adhesive comprises a pressure sensitive adhesive.

11. The method of claim 8 further comprising applying the adhesive of the label to a beer bottle.

12. The method of claim 8 wherein printing comprises gravure printing.

13. The method of claim 8 wherein the ink comprises embossed metallic flakes.

14. A labeled beer bottle wherein the label comprises the label of claim 1. 10 WO 2006/033925 PCT/US2005/032784 AMENDED CLAIMS [received by the International Bureau on 16 February 2005 (16.02.06); original claims 1 and 8. amended (2 pages)] What is claimed is: 1. A label comprising: a unprimed polypropylene facestock having an upper surface and a lower surface; a pressure sensitive adhesive layer in contact with the lower surface of the facestock; a solvent-based ink layer printed on the upper surface of the facestock; and a varnish overprint coating overlying the ink layer. 2. The label of claim 1 wherein the upper surface of the facestock is corona treated. 3. The label of claim I wherein the overprint coating comprises a two component varnish. 4. The label of claim 1 wherein the overprint coating comprises a cationic varnish. 5. The label of claim 1 wherein the label is a beer bottle label. 6. The label of claim I wherein the overprint coating is the exterior layer of the label. 7. The label of claim 1 wherein the ink comprises embossed metallic flakes. 8. A method for making printed labels comprising: providing an unprimed biaxially oriented polypropylene facestock having an upper surface and a lower surface; corona treating the upper surface of the facestock; printing a solvent based ink directly onto the upper surface of the facestock to form a print layer; 11 WO 2006/033925 PCT/US2005/032784 drying the solvent based ink; coating the print layer with a varnish overprint coating; and applying an adhesive to the lower surface of the facestock. 9. The method of claim 8 wherein the overprint coating comprises a two component varnish 10. The method of claim 8 wherein the adhesive comprises a pressure sensitive adhesive. 11. The method of claim 8 further comprising applying the adhesive of the label to a beer bottle. 12. The method of claim 8 wherein printing comprises gravure printing. 13. The method of claim 8 wherein the ink comprises embossed metallic flakes. 14. A labeled beer bottle wherein the label comprises the label of claim 1 12