MX2010010941A - Method for applying a pressure sensitive shrink label to an article. - Google Patents

Abstract

A method of applying a label (12) to an article (10), the method comprising : - providing an article having a surface comprising at least one compound curve (16); - providing a label comprising (i) a heat shrinkable film having an inner surface and an outer surface; and (ii) a layer of pressure sensitive adhesive on the inner surface of the heat shrinkable film, wherein the label has a first edge and a contact region,- - contacting the adhesive layer in the contact region of the label with the article; - and applying heat and pressure simultaneously to the label in a direction from the contact region to the first edge such that the first edge of the label adheres to the article and the label shrinks to conform to the compound curve of the article, wherein the heat and pressure are applied by at least one hot air knife assembly comprising a source of heated air, a flow control mechanism and one or more hot air slots.

Description

METHOD FOR APPLYING A CONTRAIBLE LABEL PRESSURE SENSITIVE TO AN ARTICLE Field of the Invention This invention relates to shrinkable pressure sensitive labels. More specifically, the invention relates to pressure sensitive labels that have superior adaptability to packages having complex shapes, and to methods for applying such labels.

Background of the Invention It is common practice to apply labels to containers or bottles to provide information such as container supplier or container contents. Such containers and bottles are available in a variety of shapes and sizes to contain many different types of materials such as detergents, chemicals, personal care products, motor oil, beverages, etc.

Polymeric film materials and film printing surfaces have been described for use as labels in various fields. Polymeric labels are increasingly desired for many applications, particularly transparent polymeric labels since they provide an unlabeled appearance to decorated glass and plastic containers. Paper labels block the visibility of the container and / or contents in the container. Transparent polymer labels improve the visual aesthetics of the packaging, and therefore of the product, and its use has increased more rapidly than paper labels in the packaging decoration market since the consumer products companies continuously try to improve the appearance of their products. Polymer film labels also have superior mechanical characteristics, such as tensile strength and abrasion resistance.

Traditional pressure sensitive adhesive (PSA) labels often have difficulty easily adhering to containers having curved surfaces and / or complex shapes without wrinkling, folding or peeling off the curved surfaces. The label size of traditional PSA labels is limited to no larger than 1/4 inch (6.35 millimeters) away from the edge (beginning) of the curvature of a container or article. Shrink sleeve labels have been commonly used in these types of composite containers. The labeling operations are carried out using processes and methods that require the formation of a tube or sleeve of shrinkable heat film that is placed on the container and heated to shrink the film to fit the size and shape of the container. Alternatively, the packages are completely wrapped with a shrinkable label using a process wherein the shrink film is applied to the container directly from a continuous roll of film material and then heat is applied to adjust the wrapped label in the container. container. However, defects in the label can occur during labeling operations of bottles with simple or compound shapes during the application or in subsequent application processes. These erroneously applied labels result in large amounts of waste or additional processing steps, which can be expensive.

The present invention provides a pressure sensitive adhesive label that can be applied to packages and articles on complex shapes and composite curves with less required material and less cost than for shrink wrap or shrink sleeve labels. In addition, the labels of the present invention allow the user to expand the advertising or graphics region of traditional pressure sensitive labels in packages and articles having complex shapes and / or compound curves.

Brief Description of the Invention A label is provided for use on a curved or non-planar surface comprising a heat shrinkable film and a pressure sensitive adhesive. In one embodiment, a pressure sensitive adhesive label is provided for application to a surface having at least one composite curve, the label comprising: a heat shrinkable film having an internal surface and an external surface, and a machine direction and a transverse direction, the film has a main shrinkage S in at least one direction of at least 10% at 90 ° C, where the contraction in the other direction is S ± 20%; and a layer of pressure sensitive adhesive on the inner surface of the heat shrinkable film. The shrink film has a moderate and balanced contraction in the machine direction and in the transverse direction. In one embodiment, the film has a last contraction S in at least one direction of at least 10% at 90 ° C, and the contraction in the other direction is S ± 10%. The label may additionally include a release liner removably adhered to the adhesive layer.

An article bearing a label is also provided, comprising: an article having a surface comprising at least one composite curve; and a pressure sensitive label comprising a heat shrinkable film having an inner surface and an outer surface, and a layer of pressure sensitive adhesive on the inner surface of the heat shrinkable film, wherein the label is applied to at least one composite curve.

A method for applying a label to an article is provided wherein the article has a surface having at least one composite curve. The method comprises: (a) providing an article having a surface comprising at least one composite curve; (b) providing a label comprising (i) a heat shrinkable film having an internal surface and an external surface and (ii) a layer of pressure sensitive adhesive on the inner surface of the heat shrinkable film, wherein the label has a central portion and a peripheral portion; (c) contacting the adhesive layer of the central portion of the label with the article; (d) applying pressure to the label in an exterior direction from the central portion to the peripheral portion, wherein at least a portion of the label is applied to at least one composite curve of the article; and (e) applying heat to at least a portion of the label to contract at least the portion of the label and adhering the label to the article. After or during the application of heat, the label can be compressed or pressed to fully adhere the label to the article and eliminate any remaining defects on the label.

In one aspect of the invention, there is provided a method for applying a label to an article, the method includes the steps of: providing an article having a surface that includes at least one composite curve; providing a label that includes (i) a heat shrinkable film having an inner surface and an outer surface; and (ii) a layer of pressure sensitive adhesive on the inner surface of the heat shrinkable film, wherein the label has a first edge and a contact region; contacting the adhesive layer in the contact region with the article; and applying heat and pressure to the label in one direction from the contact region to the first edge such that the first edge of the label is adhere to the article and the label is contracted simultaneously to the composite curve of the article, wherein the heat and pressure are applied by at least one hot air knife assembly comprising a heated air source, a flow control mechanism and a or more hot air blade slots.

In one embodiment, the tag includes a center and a second edge opposite the first edge, and the contact region is near or in the center of the tag. In another embodiment, the tag includes a second edge opposite the first edge and the contact region is near the second edge of the tag.

The heat and pressure can be applied to the label by a hot air knife assembly that includes at least two hot air knife slots that rotate externally from the center of the label to the first and second edges to adhere the label to the Article.

In one embodiment of the method of the present invention, a first hot air knife slot applies heat and pressure to the center of the label externally to the first edge of the label, and a second hot air knife slot applies heat and pressure to the center of the label externally to the second edge of the label. The article can rotate approximately 180 ° before the application use of heat and pressure by the second hot air knife slot to the label.

Brief Description of the Drawings Figure 1 illustrates a front view of a container to which the label of the present invention has been applied, with respect : i to pressure sensitive labels of the prior art.

Figures 2A to 2D illustrate the container labeled before and after the application of heat to the label.

Figures 3A to 3D illustrate the embodiments of the packages having complex shapes and compound curves to which the label of the present invention is applied.

Figures 4A and 4B illustrate front views of the embodiments of the containers having irregular surfaces.

Figure 5 is a three-dimensional view of a portion of a labeled article having a composite curve.

Figures 6A-6D schematically illustrate the process for applying the label to an article having a composite curve.

Figures 7A and 7B schematically illustrate one embodiment of the process for applying a label to an article where an oscillating beam is used.

Figures 8A and 8B are schematic views of an air knife assembly for applying heat and pressure simultaneously to a label.

Figures 9A-9E are schematic views of a process for applying a label to an article using the multiple air knife slots.

Detailed description of the invention Pressure-sensitive adhesive labels are provided provided that they can improve the appearance of the labeled containers and articles by adapting to the contours of the container or article and providing an enlarged label appearance. End users and product designers must currently alter their designs to adapt them to the limitations of traditional product decoration technologies. The labels of the present invention provide designers with more freedom in product designs to create greater shelf appeal and contain more information.

Packaging and articles with compound curves have to be commonly wrapped in their entirety with the shrinkable film to label or embellish the article. The labels of the present invention are capable of expanding the label over complex curves without having to completely wrap the article. This partial label coverage affects the cost of the product as well as the appearance of the product. Common pressure sensitive labels can not be applied to containers and items without the undesirable folding and wrinkling of the label. "Folding" is defined as the accumulation of excess label material that is lifted and detached from the article to which the label is applied.

The labels of the present invention provide significant processing advantages over traditional shrinkable labels. For example, the shrinkable pressure-sensitive tags of the present invention allow more traditional printing and secondary processes such as lamination and thermal printing. Where common collapsible labels are to be printed on the secondary surface, the labels of the present invention can be printed on the surface, which improves the color quality, sharpness and texture of the printed image. The label film can be printed by water-based flexographic printing, UV flexographic, UV letterpress, UV filter, solvent rotogravure and thermal lamination printing.

Pressure sensitive labels comprise (a) a heat shrinkable polymer film having an internal surface and an external surface and a machine direction and a transverse direction; and (b) a layer of pressure sensitive adhesive on the inner surface of the heat shrinkable film. The contraction of the heat shrinkable polymer film is balanced in the machine direction and in the transverse direction. In at least one direction, the main shrinkage (S) is at least 10% at 90 ° C and in the other direction, the shrinkage is S ± 20%. As an illustration of the balanced contraction, if the contraction in the machine direction is 40% at 105 ° C, then the contraction in the transverse direction is 40% ± 20%, or within the range of 20% to 60% at 105 ° C. In one embodiment, the main contraction (S) is at least 10% at 90 ° C and in the other direction, the contraction is S ± 10%. As used in this, the The term "principal contraction" means that the maximum shrinkage of the film is capable of reaching a particular shrinkage temperature, as measured by the ASTM Q 1204 method.

The labels are not provided as a sleeve or shrink tube that encapsulates the entire article or as a shrink wrap label that wraps around the article and forms a joint where the ends of the label meet. The present labels can be provided in a variety of forms to suit the article or container in which they are applied, giving the container designer greater latitude in package configuration and label design than with traditional pressure sensitive labels or shrink wrap or shrink sleeve labels. The labels can be cut into the desired shape by any known method, including, for example, puncture and laser cutting. In one embodiment, the label is punctured into a specific configuration that compensates for the shrinkage of the label and the shape of the article to which it is applied.

Because the label is adaptable, the label or graphics area of the labeled container can be further expanded over the edges of the container and over the compound curved areas of the container. The label can be 10% to 30% larger than a standard PSA label. As used herein, the term "composite curve" means a surface that has no direction in which there is no curvature. For example, the surface of a sphere or the surface of an ellipsoid has a curvature in each direction, and therefore has compound curves. A cylinder, on the other hand, has a surface on which there is at least one direction in which there is no curvature. Thus, a simple cylinder has no compound curves.

Figure 1 illustrates the enlarged label area of the pressure-sensitive shrinkable label of the present invention. The bottle 10 has a shrinkage sensitive label 12 adhered to it. Dashed line 14 indicates the outer limit of the labels sensitive to standard pressure. A standard pressure sensitive label (ie, non-shrinkable) can not extend over the areas of the bottle having the compound curves 16 (the area between the internal broken line and the external solid line). When the label 12 is initially applied to the bottle 10, creases and wrinkles may form near the perimeter of the label in the areas of the bottle having compound curves 16.

Once the pressure sensitive label is applied to the container, the heat is applied as necessary to eliminate any defects in the label application such as creases, edge lift and wrinkles. In one embodiment, the pressure and / or compression can be used in addition to the application of heat to eliminate any defect.

With reference to Figures 2A-2D, the present label and the method for applying the label are illustrated. In Figures 2A and 2B, a label 12 that includes a shrinkable film having a continuous layer of pressure sensitive adhesive applied thereto is applied to a package 10 having composite curves around the circumference of the package, and then pressed . No heat is applied to the label. The label 12 extends over the composite curves 16 where the folds 18 are formed near the label perimeter 20. Figures 2C and 2D show the labeled package of Figures 2A-2B after the heat is applied to the label. The folds 18 have been removed and the label 12 conforms to the composite curves of the package 10 near the label perimeter 20 without any defects.

The article or container in which the label is applied can be provided in a variety of shapes or profiles. Non-limiting examples of convenient items include containers with and without closures, trays, lids, toys, accessories, etc. The article or container can be made of any polymer, glass, or conventional metal such as aluminum. Examples of suitable polymeric materials include high density polyethylene (HDPE), low density polyethylene (LDPE), polyethylene terephthalate (PET), polypropylene, polyvinyl chloride, polycarbonate, nylon, ethylene -Fluorinated propylene, polystyrene, etc. The item or packaging is I it can do for a number of various processes known in the art, such as blow molding, injection molding, thermal forming, rotary molding and the like.

Useful packages include, for example, a bottle having a closure on top of the bottle, a reverse bottle having a closure at the bottom of the bottle, a bottle with a pumping distributor or a distributor for forming foam, a tube with a closure and a squeeze bottle with a closure.

The container or article can have a transparent appearance. In one embodiment, the package or article has a translucent appearance. The translucent appearance can be achieved by, for example, treatments of the transparent container or article, addition of ingredients such as dyes and nacreous agents based on polymers, the use of polypropylene and / or polyethylene which are mixed with clarifying agents. Treatments include, for example, spray coating, sandblasting, and surface mold treatment.

The package or article may include aesthetic features, including, for example, textures, embossments, optical images, opaque or matte color, holograms, etc. The surface of the container or article can be treated before the application of the label. For example, the surface of the container or article can be flame treated or a base coat can be applied.

Figures 3A, 3B and 3C each illustrate a container that It has a complex shape and compound curves. Figure 3A is a front view of a package 30a having a symmetrical spherical shape wherein the package has a sharp concave area 32 in the lid and a wider convex area 33 towards the bottom. Commonly, a shrink sleeve would be used to provide a functional label for this container. With the present invention, a shrinkable pressure sensitive label 31 can be smoothly applied to the package 30a without the appearance of label defects. Figure 3B is a front view of a package 30b having an asymmetric shape wherein one side of the package has a concave area 34 and a convex area 35 and opposing side bends in a substantially similar manner along the length of the package. The conventional method for labeling the container 30b would be to apply a shrink sleeve label that conforms to the complex shape of the container. A pressure sensitive shrink label 31 can be applied to the container 30b to provide a sufficient label area with much less label material. Figure 3C is a front view of a package 30c which is a reverse bottle having a closure 36 on the bottom and the label 31 applied to the front surface. Figure 3D is a side view of the container 30c. The areas 37 within the dashed lines indicate the outer limits of the standard pressure sensitive labels that can be applied to the container. The complex shape of this package requires two separate standard pressure sensitive labels to decorate the container, since the application of a continuous pressure sensitive label would result in the formation of crease and crease defects. The pressure-sensitive, removable label 31 can cover a much larger area, which provides more design options for the product designer.

Figures 4A and 4B each illustrate a container having an irregular surface. Figure 4A is a front view of a package 40a having raised ridges 42 along one side of the package. The opposite side of the package has a smooth surface. Figure 4B is a front view of a package 40b having circumferentially hollow rings 43 along the length of the package. It should be noted that articles with cylindrical shape having areas of compound curves such as containers 40a and 40b are not excluded from the articles claimed herein.

Figure 5 is a three-dimensional view schematic of a portion of a container in which the label has been applied. The package 50 has a surface comprising a composite curve. The label 52 is applied to the package and covers a portion of the composite curved area. Line 54 indicates the external limit at which common pressure sensitive labels can be applied without the formation of defects on the label. The area 56 indicates the enlarged sign area that can be obtained with the present labels without the formation of defects such as wrinkles, lifting edges or creases.

Shrinkable film The polymeric films useful in the constructions of the label of the present invention possess balanced shrinkage characteristics. The balanced shrinkage characteristics allow the film to tense the folds and wrinkles formed initially on the label when the label is applied on the curved surfaces and allows the folds and wrinkles to be compressed with minimal distortion of the graphics on the label. Films that have an unbalanced contraction, that is, films that have a high level of contraction in one direction and a low to moderate level of contraction in the other direction are not particularly useful because while the folds can be eliminated in a direction, in the other direction the formation of creases is aggravated. Useful films that have a balanced traction allow a wider variety of label forms to be applied to a wider variety of packaging forms.

In one embodiment, the polymeric film has a main shrinkage (S) which is measured by the ASTM D1204 process in at least one direction of at least 10% at 90 ° C and in the other direction, the shrinkage is S ± 20 %. In another embodiment, the film has a main shrinkage (S) in at least one direction from about 10% to about 50% at 70 ° C and in the other direction, the shrinkage is S ± 20%. In one embodiment, the main contraction (S) is at least 10% at 90 ° C and in the other direction, the contraction is S ± 10%. The shrinkage initiation temperature of the film, in one embodiment, is about 60 ° C to about 80 ° C.

The shrinkable film must be able to contract thermally and still have sufficient stiffness to be distributed using conventional labeling equipment and processes, including printing, puncture and label transfer. The stiffness of the film required depends on the size of the label, speed of application and labeling equipment that is used. In one embodiment, the shrink film has a machine direction stiffness of at least 5mN, as measured by the L & W resistance test. In one embodiment, the shrink film has a stiffness of at least 10mN, or at least 20mN. The stiffness of the shrink film is important for the proper distribution of the labels on a release plate at higher linear speeds.

In one embodiment, punctured labels are applied to the article or package in an automated labeling process at a linear speed of at least 100 units per minute, or at least 250 units per minute or at least 500 units per minute. .

In one embodiment, the shrink film has a secant modulus of 2% as measured by ASTM D882 at the address of machine from approximately 20,000 to approximately 400,000 psi, and in the transverse (or cross) direction (TD) from approximately 20,000 to approximately 400,000 psi. In another embodiment, the secant modulus of 2% of the film is from about 30,000 to about 300,000 in the machine direction and from about 30,000 to about 300,000 in the transverse direction. The film may have a lower modulus in the transverse direction than in the machine direction (MD) to distribute the label easily while keeping the module sufficiently low in TD for the ability to adapt and / or compress.

The polymeric film can be made by conventional processes. For example, the film may be produced using a double bubble process, tensioning process or may comprise a blown film.

The shrinkable film useful in the label can be a single layer construction or a multi-layer construction. The layer or layers of the shrinkable film can be formed from a polymer chosen from polyester, polyolefin, polyvinyl chloride, polystyrene, polylactic acid, copolymers and mixtures thereof.

Polyolefins comprise homopolymers or copolymers of olefins which are aliphatic hydrocarbons having one or more carbon-carbon double bonds. The olefins include alkenes comprising 1-alkenes, also known as alpha-olefins, such as 1-butene and internal alkenes having the carbon-carbon double bond in carbon chain non-terminal carbon atoms, such as 2-butene, cyclic olefins having one or more carbon-carbon double bonds, such as cyclohexene and norbornadiene, and cyclic polyenes which are non-cyclic aliphatic hydrocarbons having two or more carbon-carbon double bonds, such as 1,4-butadiene and isoprene. The polyolefins comprise alkene homopolymers of a single alkene monomer, such as a polypropylene homopolymer, alkene copolymers of at least one alkene monomer and one or more additional olefin monomers where the aforementioned first alkene is the major component of the copolymer , such as a propylene-ethylene copolymer and propylene-ethylene-butadiene copolymer, cyclic olefin cyclic monomer single homopolymers, and cyclic olefin copolymers of at least one cyclic olefin monomer and one or more monomers of olefin in which the first mentioned cyclic olefin is the main component of the copolymer, and mixtures of any of the above olefin polymers.

In one embodiment, the shrink film is a multilayer film comprising a base layer and at least one surface layer. The surface layer can be a layer printable surface. In one embodiment, the multilayer shrinkable film comprises a base and two surface layers, wherein at least one surface layer is printable. The multilayer shrinkable film can be a co-extruded film.

The film can range in thickness from 0.5-20 (0.0127-0.508), or 0.5-12 (0.0127-0.3048), or 0.5-8 (0.0127-0.2032), or 1-3 (0.0254-0.0762) mils (mm). The difference in the layers of the film may include a difference in the thermoplastic polymer components, additive components, orientation, thickness, or combination thereof. The thickness of the base layer can be 50-95%, or 60-95% or 70-90% of the thickness of the film. The thickness of a surface layer or a combination of two surface layers may be 5-50%, or 5-40% or 10-30% of the film thickness.

The film can be further processed on a top and bottom surface or surfaces to improve performance in terms of printing ability or adhesion to an adhesive. The treatment may comprise the application of a surface layer such as, for example, a lacquer, applying a high energy discharge to include a corona discharge to a surface, applying a flame treatment to a surface, or a combination of any of the previous treatments. In one embodiment of the invention, the film is treated on both surfaces, and in another embodiment the Film is treated on one surface with a corona discharge and blown on the other surface.

If desired, the layers of the shrink film may contain pigments, fillers, stabilizers, light protecting agents or other suitable modifying agents. The film may also contain antiblock, slip and antistatic additives. Useful antiblocking agents include inorganic particles, such as clays, talcum, calcium carbonate and glass. Sliding additives useful in the present invention include polysiloxanes, waxes, fatty amides, fatty acids, metal and macroparticulate soaps such as silica, synthetic amorphous silica and polytetrafluoroethylene powder. Antistatic agents useful in the present invention include alkali metal sulphonates, polyether modified polydiorganosiloxanes, polyalkylphenylsiloxanes and tertiary amines.

In one embodiment, the shrink film is microperforated to allow trapped air to be released from the interface between the label and the article to which it adheres. In another embodiment, the shrink film is permeable to allow liquid to exit the adhesive or surface of the article. In one embodiment, the vents or ventilation slits are provided in the shrink film.

Adhesives A description of the useful pressure sensitive adhesives can be found in Encyclopedia of PolymerScience and Engineering, Vol. 13, Wiley-lnterscience Publishers (New York, 1988). An additional description of the useful PSAs can be found in Polymer Science and Technology, Vol. 1, Interscience Publishers (New York, 1964). Conventional PSAs are useful, including acrylic-based PSAs, rubber-based PSAs, and silicone-based PSAs. The PSA can be a solvent or water based adhesive. The hot melt adhesives can also be used. In one embodiment, the PSA comprises an acrylic emulsion adhesive.

The adhesive and the side of the film to which the adhesive is applied have sufficient compatibility to allow a good adhesive fixation. In one embodiment, the adhesive is chosen so that the labels are released cleanly from the PET containers up to 24 hours after application. The adhesive is also chosen so that the adhesive components are not transferred to the film.

In one embodiment, the adhesive can be formed from an acrylic-based polymer. It is contemplated that any acrylic-based polymer capable of forming an adhesive layer with sufficient adhesion to adhere to a substrate may function in the present invention. In certain embodiments, the acrylic polymers for the pressure sensitive adhesive layers include those formed from the polymerization of at least one alkyl acrylate monomer containing from about 4 to about 12 carbon atoms in the the alkyl group, and are present in an amount of about 35-95% by weight of polymer or copolymer, as described in U.S. Patent No. 5,264,532. Optionally, the pressure sensitive adhesive based on acrylic can be formed from a single polymeric species.

The glass transition temperature of a PSA layer comprising the acrylic polymers can be varied by adjusting the amount of polar, or "hard", monomers in the copolymer, as taught by U.S. Patent No. 5,264,532, incorporated herein by reference. reference. The higher the weight percentage of the hard monomers in an acrylic copolymer, the higher the glass transition temperature. The contemplated hard monomers useful for the present invention include the vinyl esters, carboxylic acids, and methacrylates, at concentrations by weight ranging from about zero to about thirty-five weight percent of the polymer.

The PSA may be based on acrylic such as those taught in US Patent No. 5,164,444 (acrylic emulsion), US Patent No. 5,623,011 (adhesive acrylic emulsion) and US Patent No. 6,306,982. The adhesive may also be rubber based such as those taught in U.S. Patent No. 5,705,551 (hot melt rubber). It can also be a radiation curable mixture of monomers with initiators and other ingredients such as those taught in U.S. Patent No. 5,232,958 (UV cured acrylic) and U.S. Patent No. 5,232,958 (cured by EB). The descriptions of these patents that relate to acrylic adhesives are incorporated herein by reference.

Commercially available PSAs are useful in the invention. Examples of these adhesives include the heat-melted PSAs available from H.B. Fu I le r Company, St. Paul, Minn, as HM-1597, HL-2207-X, HL-21 15-X, HL-2193-X. Other useful commercially available PSAs include those available from Century Adhesives Corporation, Columbus, Ohio. Another useful acrylic PSA comprises a mixture of emulsion polymer particles with dispersion adhesive particles as generally described in Example 2 of US Patent No. 6, 306, 982. The polymer is made by polymerization of the acrylate emulsion of 2-ethylhexyl, vinyl acetate, dioctyl maleate, and acrylic and methacrylic comonomers as described in U.S. Patent No. 5,164,444.1 which results in the latex particle size of about 0.2 micron average diameter and a gel content of approximately 60%.

A commercial example of a hot melt adhesive is H2187-01, sold by Ato Findley, Inc., of Wauwatusa, Wisconsin. In addition, the PSAs of rubber-based block copolymer disclosed in U.S. Patent No. 3,239,478 they may also be used in the adhesive constructions of the present invention, and this patent is incorporated herein by reference to its description of such heat-melt adhesives which are described in detail below.

In another embodiment, the pressure sensitive adhesive comprises the rubber-based elastomer materials containing the useful rubber-based elastomer materials including the linear, branched, grafted, or radial block copolymers represented by the double-block structure A- -B, triple block A-B-A, radial or coupled structures (A-B) m, and combinations thereof where A represents a hard thermoplastic phase or block that is not elastic or lustrous or crystalline at room temperature but fluid at higher temperatures, and B represents a soft block that is elastic or elastomeric in use or room temperature. These thermoplastic elastomers can comprise from about 75% to about 95% by weight of elastic segments and about 5% to about 25% by weight of non-elastic segments.

The non-elastic segments or hard blocks comprise polymers of mono- and polycyclic aromatic hydrocarbons, and more particularly vinyl-substituted aromatic hydrocarbons which may be monocyclic or bicyclic in nature. Elastic materials such as polyisoprene, polybutadiene, and styrene-butadiene rubbers can be used to form the block or elastic segment. Particularly useful elastic segments include polydienes and saturated oieffine rubbers of the ethylene / butylene or ethylene / propylene copolymers. The main rubbers can be obtained from the corresponding unsaturated polyalkylene portions such as polybutadiene and polyisoprene by hydrogenation thereof.

The block copolymers of the vinyl aromatic hydrocarbons and conjugated dienes that can be used include any of those exhibiting elastomeric characteristics. The block copolymers can be double block, triple block, multiple block, star block, polyblock or grafted block copolymers. Through this specification, the terms double block, triple block, multiple blocks, polyblocks, and graft blocks or grafted with respect to the structural characteristics of the block copolymers will give their normal meaning as defined in the literature such as in Encyclopedia of Polymer Science and Engineering, Vol. 2, (1985) John Wiley & Sons, Inc., New York, pp. 325-326, and by J. E. McGrath in Block Copolymers, Science Technology, Dale J. Meier, Ed., Harwood Academic Publishers, 1979, on pages 1-5.

Such block copolymers may contain various ratios of conjugated dienes to vinyl aromatic hydrocarbons including those containing up to about 40% by weight of the vinyl aromatic hydrocarbon. Accordingly, the multi-block copolymers can be used, which are symmetric or asymmetric linear or radial and having structures represented by the formulas, A-B-A, A-B-A-B, B --A - B, (AB) or, i, 2 BA, etc., wherein A is a polymer block of a vinyl aromatic hydrocarbon or a block of vinyl aromatic hydrocarbon / conjugated diene copolymer, and B is a block of elastic polymer of a conjugated diene.

The block copolymers can be prepared by any of the polymerization or block copolymerization processes that include the sequential addition of monomer, incremental addition of monomer, or coupling techniques as illustrated in, for example, US Patent Nos. 3,251,905; 3,390,207; 3,598,887; and 4,219,627. As well-known sharp copolymer blocks, it can be incorporated into the multi-block copolymers by copolymerization of a mixture of conjugated diene and vinyl aromatic hydrocarbon monomers using the difference in their rates of copolymerization reactivity. Several patents describe the preparation of multiple block copolymers containing sharp copolymer blocks including US Patent No. 3,251,905; 3,639,521; and 4,208,356, the descriptions of which are incorporated herein by reference.that.

The conjugated dienes that can be used to prepare the polymers and copolymers are those containing from 4 to about 10 carbon atoms and more generally, from 4 to 6 carbon atoms. Examples include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, chloroprene, 1,3-pentadiene, 1,3-hexadiene, etc. Mixtures of thconjugated dienes can also be used.

Examples of vinyl aromatic hydrocarbons that can be used to prepare the copolymers include styrene and various substituted styrenes such as o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, alpha-methylstyrene, beta-methylstyrene. , p-isopropylstyrene, 2,3-dimethylstyrene, o-chlorostyrene, p-chlorostyrene, o-bromostyrene, 2-chloro-4-methylstyrene, etc.

Many of the above-described copolymers of conjugated dienes and vinyl aromatics are commercially available. The number average molecular weight of block copolymers, before hydrogenation, is from about 20,000 to about 500,000, or about 40,000 to about 300,000.

The average molecular weights of the individual blocks within the copolymers can vary within certain limits. In most cases, the aromatic vinyl block will have a number average molecular weight in the order of about 2000 to about 125,000, or between approximately 4000 and 60,000. The conjugated diene blocks before or after hydrogenation will have number average molecular weights in the order of about 10,000 to about 450,000, or about 35,000 to 150,000.

Also, prior to hydrogenation, the vinyl content of the conjugated diene portion is generally from about 10% to about 80%, or about 25% to about 65%, particularly 35% to 55% when it is desired that the copolymer of Modified block exhibit rubber elasticity. The vinyl content of the block copolymer can be measured by means of nuclear magnetic resonance.

Specific examples of the double block copolymers include styrene-butadiene (SB), styrene-isoprene (SI), and the hydrogenated derivatives thereof. Examples of triple block polymers include styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), alpha-methylstyrene-butadiene-alpha-methylstyrene, and methylstyrene-isoprene-alpha-methylstyrene. . Examples of the commercially available block copolymers useful as adhesives in the prt invention include those available from Kraton Polymers LLC under the trademark KRATON.

During the hydrogenation of SBS copolymers comprising an elastic segment of a mixture of the isomers 1.4 and 1.2, a styrene-ethylene-butylene-styrene block copolymer (SEBS) is obtained. Similarly, the hydrogenation of a SIS polymer produces a styrene-ethylene-propylene-styrene block copolymer (SEPS).

The selective hydrogenation of the block copolymers can be carried out by a variety of well known processes including hydrogenation in the prce of such catalysts as Raney nickel, noble metals such as platinum, palladium, etc., and the soluble transition metal catalysts. . Suitable hydrogenation processes that can be used are those wherein the diene-containing polymer or copolymer is dissolved in an inert hydrocarbon diluent such as cyclohexane and is hydrogenated by reaction with hydrogen in the prce of a soluble hydrogenation catalyst. Such procedures are described in U.S. Patent Nos. 3, 113,986 and 4,226,952, the descriptions of which are incorporated herein by reference. Such hydrogenation of the block copolymers is carried out in a manner and to the degree to produce the selectively hydrogenated copolymers having a residual non-saturation content in the polydiene block of from about 0.5% to about 20% of their original unsaturated content before hydrogenation.

In one embodiment, the conjugated diene portion of the block copolymer is at least 90% saturated and more frequently at least 95% saturated while the Aromatic portion of vinyl is not significantly hydrogenated. Particularly useful hydrogenated block copolymers are hydrogenated products of the styrene-isoprene-styrene block copolymers such as a styrene- (ethylene / propylene) -styrene block polymer. When a polystyrene-polybutadiene-polystyrene block copolymer is hydrogenated, it is desirable that the ratio of 1,2-polybutadiene to 1,4-polybutadiene in the polymer be from about 30:70 to about 70:30. When such a block copolymer is hydrogenated, the resulting product resembles a regular copolymer block of ethylene and 1-butene (EB). As noted above, when the conjugated diene is used as isoprene, the resulting hydrogenated product resembles a regular copolymer block of ethylene and propylene (EP).

A number of selectively hydrogenated block copolymers are commercially available from Kraton Polymers under the general trade designation "Kraton G." An example is Kraton G1652 which is a triple block of hydrogenated SBS comprising about 30% by weight of end blocks of styrene and a middle block which is a copolymer of ethylene and 1-butene (EB). A lower molecular weight version of G1652 is available under the designation Kraton G1650. Kraton G1651 is another SEBS block copolymer containing approximately 33% by weight of styrene.

Kraton G1657 is a double-block copolymer of SEBS containing approximately 13% by weight of styrene. This styrene content is lower than the styrene content in Kraton G1650 and Kraton G1652.

In another embodiment, the selectively hydrogenated block copolymer is of the formula: where n = 0 or 1; or is 1 to 100; p is 0 or 1; each B before the hydrogenation is predominantly a polymerized conjugated diene hydrocarbon block having a number average molecular weight of from about 20,000 to about 450,000; each A is predominantly a polymerized vinyl aromatic hydrocarbon block having a number average molecular weight of from about 2000 to about 115,000; the blocks of A constitute from about 5% to about 95% by weight of the copolymer; and the non-saturation of block B is less than about 10% of the original non-saturation. In other embodiments, the non-saturation of block B is reduced during hydrogenation to less than 5% of its original value, and the average non-saturation of the hydrogenated block copolymer is reduced to less than 20% of its original value.

Block copolymers can also include functionalized polymers such as can be obtained by the reaction of a monocarboxylic or dicarboxylic acid reagent not saturated with alpha- or beta-olefins in the selectively hydrogenated block copolymers of the vinyl aromatic hydrocarbons and conjugated dienes as described above. The reaction of the carboxylic acid reagent in the graft block copolymer can be effected in solutions or by a melting process in the presence of a free radical initiator.

The preparation of several selectively hydrogenated block copolymers of the conjugated dienes and vinyl aromatic hydrocarbons that have been grafted with a carboxylic acid reagent is described in a number of patents including US Patent Nos. 4,578,429; 4,657,970; and 4,795,782, and the descriptions of these patents relating to selectively grafted hydrogenated block copolymers of conjugated dienes and vinyl aromatics, and the preparation of such compounds are incorporated herein by reference. U.S. Patent No. 4,795,782 describes and provides examples of the preparation of block copolymers grafted by the solution and melt process. U.S. Patent No. 4,578,429 contains an example of the grafting of Kraton G1652 polymer (SEBS) with maleic anhydride with 2,5-dimethyl-2,5-di (t-butylperoxy) hexane by a melting reaction in a twin screw extruder .

Examples of hydrogenated copolymers selectively treated with commercially available styrene and butadiene maleate include Kraton FG1901X, FG1921X, and FG1924X, often referred to as copolymers of hydrogenated SEBS selectively treated with maleate. FG1901X contains about 1.7% by weight of binding functionality as succinic anhydride and about 28% by weight of styrene. FG1921X contains about 1% by weight of binding functionality as succinic anhydride and 29% by weight of styrene. FG1924X contains about 13% styrene and about 1% binding functionality as succinic anhydride.

Useful block copolymers are also available from Nippon Zeon Co., 2-1, arunochi, Chiyoda-ku, Tokyo, Japan. For example, Quintac 3530 is available from Nippon Zeon and is believed to be a linear block copolymer of styrene-isoprene-styrene.

Unsaturated elastomeric polymers and other polymers and copolymers that are not intrinsically adhesive can be made adhesive when they are composed of an external tackifier. Adhesion agents are generally hydrocarbon resins, wood resins, resins, resin derivatives, and the like, which when present at concentrations ranging from about 40% to about 90% by weight of the total adhesive composition, or about 45% to about 85% by weight, impart pressure sensitive adhesive characteristics to the elastomeric polymer adhesive formulation. Compositions containing less than about 40% by weight of the adhesive agent additive generally do not show sufficient "fast adhesion", or initial adhesion, to function as a pressure sensitive adhesive, and are therefore not inherently adhesive. The compositions with too high a concentration of adhesive agent additive, on the other hand, generally show a too low cohesive force to work correctly in most of the intended applications of the constructions made in accordance with the present invention.

It is contemplated that any adhesive agent known to those skilled in the art to be compatible with elastomeric polymer compositions can be used with the present embodiment of the invention. Such an adhesive agent, found useful, is Wingtak 10, a synthetic polyterpene resin that is liquid at room temperature, and sold by Goodyear Tire & Rubber Company of Akron, Ohio. Wingtak 95 is a synthetic tackifying agent resin also available from Goodyear which predominantly comprises a polymer derived from piperylene and isoprene. Other suitable tackifying additives may include Escorez 1310, an aliphatic hydrocarbon resin, and Escorez 2596, a resin (aliphatic modified aromatic) of 5 to 9 carbon atoms, both manufactured by Exxon of Irving, Texas. Of course, as can be appreciated by those skilled in the art, a variety of different adhesive additives can be used to practice the present invention.

In addition to the tackifiers, other additives may be included in the PSAs to impart the desired characteristics. For example, plasticizers can be included, and are known to lower the glass transition temperature of an adhesive composition containing the elastomeric polymers. An example of a useful plasticizer is Shellflex 371, a naphthenic processing oil available from Shell Lubricants of Texas. Antioxidants can also be included in the adhesive compositions. Suitable antioxidants include Irgafos 168 and Irganox 565 available from Ciba-Geigy, Hawthorne, N.Y. Cutting agents such as waxes and surfactants can also be included in the adhesives.

The pressure sensitive adhesive can be applied from a solvent, emulsion or suspension, or as a hot melt. The adhesive can be applied to the internal surface of the shrinkable film by any known method. For example, the adhesive can be applied by molding, curtain coating, spraying, dipping, laminating, rotogravure or flexographic techniques. The adhesive can be applied to the shrinkable film in a continuous layer, discontinuous layer or in a pattern. The adhesive layer coated pattern covers substantially the entire inner surface of the film. As used herein, the term "substantially covers" is intended to understand the continuous pattern on the film surface, and is not intended to include the adhesive applied only on a strip along the front or rear edges of the film. the movie or as a "point union" in the movie.

In one embodiment, an adhesive cushion is applied to the portions of the adhesive layer to allow the label to adhere to articles with complex shapes. In one embodiment, the non-adhesive material such as ink spots or microgranules is applied to at least a portion of the adhesive surface to allow the adhesive layer to slide over the surface of the article while the label is being applied, and / or to allow air trapped at the interface between the label and the article to escape.

A single adhesive layer or multiple adhesive layers can be used. Depending on the shrink film used and the article or container to which the label will be applied, it may be desirable to use a first adhesive layer adjacent to the shrink film and a second adhesive layer having a different composition on the surface to be applied to the article or container to obtain sufficient adhesiveness, resistance to detachment and cutting force.

In one embodiment, the pressure sensitive adhesive has sufficient cutting or cohesive force to prevent excessive back-shrinkage of the label where it adheres to the article during the heat action after the label is placed on the article, sufficient peel strength to prevent the label film from separating from the label article and sufficient adhesion or clamping to allow proper attachment of the label to the article during the labeling operation. In one embodiment, the adhesive moves with the label while the shrink film shrinks during the application of heat. In another embodiment, the adhesive holds the label in the position so that as long as the shrink film contracts, the label does not move.

The heat-shrinkable film may include other layers in addition to the single layer or multiple layer heat shrinkable polymeric film. In one embodiment, a metallized coating of a thin metallic film is deposited on the surface of the polymeric film. The heat shrinkable film may also include a printing layer on the polymer film. The printing layer may be placed between the heat shrinkable layer and the adhesive layer, or the printing layer may be on the external surface of the shrinkable layer. In one embodiment, the film is printed in reverse with a design, image or text so that the printing side of the surface is in direct contact with the container to which the film is applied. In this modality, the movie is transparent.

The labels of the present invention may also contain a layer of an ink-receptive composition that improves the printability of the shrinkable polymer layer or metal layer, if present, and the quality of the printing layer thus obtained. A variety of such compositions are known in the art, and these compositions generally include a binder and a pigment, such as silica or talc, dispersed in the binder. The presence of the pigment decreases the drying time of some inks. Such ink-receiving compositions are described in U.S. Patent No. 6,153,288 (Shih et al.) And the description of this patent is incorporated herein by reference.

The printing layer may be an ink layer or graphics, and the printing layer may be a single color printing layer or multiple colors depending on the printed message and / or intended polish. These include variable printed data such as serial numbers, bar codes, registered trademarks, etc. The thickness of the printing layer is commonly in the range of about 0.5 to about 10 microns, and in a mode of about 1 to about 5 microns, and in another mode about 3 microns. The inks used in the printing layer include water or solvent based inks and commercially available radiation curable inks. Examples of these inks include Sun Sheen (a product of Sun Chemical identified as polyamide ink that can be diluted in alcohol), SuntexMP (a product of Sun Chemical identified as a solvent-based ink formulated for substrates coated with surface-printed acrylic, substrates coated with PVDC and polyolefin films), X-Cel (a product of Waterlnk Technologies identified as water-based film ink for printing film substrates), Uvilith AR-109 Rubine Red (a product of Dawlnk identified as an ink UV) and CLA91598F (a product of Sun Chemical identified as an ink based on black solvent with multiple bonds).

In one embodiment, the printing layer comprises a polyester / vinyl ink, a polyamide ink, an acrylic ink and / or a polyester ink. The printing layer can be formed in a conventional manner by, for example, rotogravure, flexographic or UV flexographic printing or the like, an ink composition comprising a resin of the type described above, a suitable pigment or dye and one or more volatile solvents. convenient on one or more desired areas of the film. After the application of the ink composition, the volatile solvent components of the ink composition evaporate, leaving only the non-volatile ink components to form the ink layer.

Print The adhesion of the ink to the surface of the polymeric layer of the polymeric or metal shrinkable film, if present, can be improved if necessary, by techniques well known to those skilled in the art. For example, as mentioned above, an ink base or other ink adhesion promoter can be applied to the metal layer or polymeric film layer prior to the application of the ink. Alternatively, the surface of the polymeric film can be treated with a corona or flame to improve the adhesion of the ink to the polymeric layer of the film.

Useful ink bases can be transparent or opaque and the bases can be based on solvent or water. In one embodiment, the bases are curable by radiation (for example, UV). The ink base may comprise a lacquer and a diluent. The lacquer may comprise one or more polyolefins, polyamides, polyesters, polyester copolymers, polyurethanes, polysulfones, polyvinylidinochloride, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, sodium-based ionomers or zinc or methacrylic acid salts. ethylene, polymethyl methacrylates, acrylic polymers and copolymers, polycarbonates, polyacrylonitriles, ethylene-vinyl acetate copolymers, and mixtures of two or more thereof. Examples of the diluents that can be used include alcohols such as ethanol, isopropanol and butanol; esters such as ethyl acetate, propyl acetate and butyl acetate; aromatic hydrocarbons such as toluene and xylene; ketones such as acetone and methyl ethyl ketone; aliphatic hydrocarbons such as heptane; and mixtures thereof. The ratio of the lacquer to the diluent is dependent on the viscosity required for the application of the ink base, the selection of such viscosity which is within the knowledge of the person skilled in the art. The ink base layer may have a thickness of from about 1 to about 4 microns or from about 1.5 to about 3 microns.

A transparent top or protective layer of transparent polymer may be present in the labels of the invention. The protective top or surface layer provides the desirable characteristics to the label before and after the label is attached to a substrate such as a package. The presence of a transparent top layer on the printing layer can, in some embodiments, provide additional features such as antistatic properties, stiffness and weather resistance, and the surface layer can protect the printing layer against, for example, weather, sun, abrasion, moisture, water, etc. The transparent top layer can improve the characteristics of the underlying print layer to provide a brighter and richer image. The transparent protective layer can also be designed to be resistant to abrasion, resistant to radiation (eg, UV), chemically resistant, thermally resistant to thereby protect the label and, particularly the printing layer against the degradation of such causes. The protective surface layer may also contain antistatic agents, or antiblocking agents to provide easier handling when the labels are being applied to the containers at high speeds. The protective layer can be applied to the printing layer by techniques known to those skilled in the art. The polymer film can be deposited from a solution, applied as a preformed film (laminated to the printing layer), etc.

When a transparent top or surface layer is present, it may have a single layer or multiple layer structure. The thickness of the protective layer is generally from about 12.5 to about 125 microns, and in a mode from about 25 to about 75 microns. Examples of the top layers are described in U.S. Patent No. 6,106,982 which is incorporated herein by reference.

The protective layer may comprise polyolefins, thermoplastic polymers of ethylene and propylene, polyesters, polyurethanes, polyacryls, polymethacryls, epoxide, vinyl acetate homopolymers, co- or terpolymers, ionomers, and mixtures thereof.

The transparent protective layer may contain UV light absorbers and / or other light stabilizers. Among the UV light absorbers that are useful are the hindered amine buffers available from Ciba Specialty Chemical under the trade designations "Tinuvin". Light stabilizers that can be used include the hindered amine light stabilizers available from Ciba Specialty Chemical under the trade designations Tinuvin 111, Tinuvin 123, (bis- (1-octyloxy-2,2,6,6-tetramethyl-4) -piperidinyl) sebacate; Tinuvin 622, (a polymer of dimethyl succinate with 4-hydroxy-2,2,6,6-tetramethyl-piperidinetanol); Tinuvin 770 (bis- (2,2,6,6-tetramethyl- 4-piperidinyl) -sebacate) and Tinuvin 783. Additional light stabilizers include the hindered amine light stabilizers available from Ciba Specialty Chemical under the trade designation "Chemassorb", especially Chemassorb 119 and Chemassorb 944. The concentration of the absorber of UV light and / or light stabilizer is in the range of up to about 2.5% by weight, and in an embodiment of from about 0.05% to about 1% by weight.

The clear protective layer may contain an antioxidant. Any antioxidant useful in the manufacture of thermoplastic films can be used. These include hindered phenols and organ phosphites. Examples include those available from Ciba Specialty Chemical under the trade designations Irganox 1010, Irganox1076 or Irgafos 168. The concentration of the antioxidant in the thermoplastic film composition can be in the range of up to about 2.5% by weight, and in a mode of from about 0.05% to about 1% by weight.

A release liner can be adhered to the adhesive layer to protect the adhesive layer during transportation, storage and handling prior to the application of the label to a substrate. The coating allows the efficient handling of a series of individual labels after the labels are punctured and the matrix is detached from the layer of the material of the printing surface and to the point where the individual labels are distributed in sequence in a line of labeled. The release liner may have a raised surface and / or have a non-adhesive material, such as microgranule printed ink spots, applied to the surface of the coating.

Process The process for applying labels to articles or packaging involves non-traditional operations and equipment. The process begins with the traditional dispensing equipment that separates the label from the release liner via a release plate or tip which has the label with the adhesive exposed to the container or article to be decorated. With reference to Figures 6A to 6D, the label 62, having a central portion 61 and a peripheral portion 63 surrounding the central portion and having an outer boundary defined by the label edges, is brought into contact with the container 60 by initially applying pressure to the label in the central portion. It has initial adhesion points 64 located in a more central portion of the label instead of the leading edge or peripheral portion of the label, to facilitate a more even distribution of any creases or wrinkles formed between the leading and trailing edges of the label. applied This in turn facilitates the elimination of folds or wrinkles with the application of heat.

For those articles having composite curves and relatively flat regions, the label may initially be contacted with the container not in a compound curve, but closer to or within a relatively flat area of the container surface.

In one embodiment, the label is preheated to soften the shrinkable film and / or activate the adhesive layer.

Pressure is applied to the transferred label with a series of brushes, rollers, brushes, straighteners, pneumatic rollers, or an oscillating beam in a central exterior direction, as indicated by arrows 65, to obtain intimate contact between the label and the container or article. This process is referred to herein as "rubbing". The rubbing movement from the center to the edge forces any air trapped under the label to the outer edges, as indicated by the arrows 66, and creates smaller folds and more evenly distributed at the edges of the label. Although the label covers the complex curves of the article, the excess of label material accumulates in the form of creases, pleats, channels, bubbles and other defects of application generally in the peripheral portion of the label. The heat is applied to at least one portion of the label to fully and smoothly adhere the label to the container as shown in Figure 6D.

In one embodiment, the pressure is applied to the label using an oscillating beam system equipped with a foam roll or a foam coated beam. The roller or beam with foam applies downward pressure in the longitudinal direction to the central region of the label and then proceeds to the outer edges of the label, directing any air trapped under the label and folds, wrinkles and / or other defects to the edges external labels. This embodiment is illustrated in Figure 7, wherein the container 70 having the label 71 applied thereto, is placed in a lower foam block 72a of an oscillating beam. The upper foam block 72b applies downward pressure on the label 71 in the container 70 to push the air under the central portion of the label to the periphery of the label while the label and the container are compressed between the foam blocks of the label. the oscillating beam.

Once the label is applied and the initial rubbing is completed, the excess material folds and defects of the labels are removed by heating at least a portion of the label to contract the creases and / or wrinkles. The label can be heated via a passage through a tunnel of heat, pressurized air, steam tunnel, bearings or hot forms of direct contact. In one embodiment, the label is heated to a temperature of at least 40 ° C. In one embodiment, the label is heated to at least 60 ° C, or to at least 70 ° C, or to at least 80 ° C.

A subsequent rubbing of the label can be performed to remove any remaining creases or wrinkles on the label. The pressure is applied again to the label in a central outer direction to the label. The second rubbing can be performed by a series of rollers, cleaners, straighteners, brushes, pneumatic rollers or an oscillating beam. The subsequent rubbing can be done simultaneously with the application of heat to the label, or after the application of heat.

When applying the label to an item or package, the label can initially adhere to the article by applying pressure to a contact region of the label, and then applying pressure through the label in one direction until it reaches a first edge of the label . The contact region may be in the center of the label or may be near a second edge of the label opposite the first edge. For example, the initial contact can be made in the center of the label and then the pressure is applied in an external direction to the edges or periphery of the label. Alternatively, the initial contact can be made near one edge of the label and then the pressure is applied through the label to the opposite edge of the label. When applying the label to the article or package, it is desirable to move the excess material from the label, i.e., the folds or wrinkles, to at least one edge of the label. Excess material commonly moves in the direction of compound curves, where the heat applied to the label will contract the label and allow it to conform to the composite curve and eliminate any creases or wrinkles formed. Heat and pressure can be applied to the label simultaneously.

In one embodiment of the invention, the method for applying a label to an article includes the steps of: providing an article having a surface that includes at least one composite curve; providing a label that includes (i) a heat shrinkable film having an inner surface and an outer surface; and (ii) a layer of pressure sensitive adhesive on the inner surface of the heat shrinkable film, wherein the label has a first edge and a contact region; contacting the adhesive layer in the contact region with the article; and applying heat and pressure simultaneously to the label in a direction from the contact region to the first edge such that the first edge of the label adheres to the article and the label contracts to conform to the composite curve of the article, wherein the heat and I pressure is applied by a heated adaptive membrane. The ! I contact region can be located at or near the center of the label. Alternatively, the contact region may be near a second edge of the label opposite the first edge.

Figure 8 illustrates an embodiment of the invention wherein a hot air blade assembly is used to apply the label to the article or package. A label can be applied to one or both sides of the container. For simplicity of illustration, a label applies only to a surface of the package of Figure 8. The hot air knife assembly includes a source of hot air, a flow control mechanism and one or more hot air knife slots. . As shown in Figure 8A, two hot air knife slots 84a, 84b direct hot air at a high velocity to the central region 83c of the label 82. The label 82 is first applied to the central region 83c of the container 81. with a detachment tip distribution process (not shown) with the leading edge (first edge 83a) and the trailing edge (second edge 83b) not adhered. The container with the label attached to it is transported to the air knife assembly via a conveyor. Depending on the size and configuration of the package, the hot air knife slots and / or additional hot air mounts can be used to apply heat and pressure to the label. As shown in Figure 8B, the air blades 84a, 84b are made rotate externally to direct hot air from the central region of the tag 83c to the first edge 83a and second edge 83b of the tag 82. While the hot air is forced against the tag 82, the air between the label and package 81 is pushed towards the edges 83a, 83b of the label to smooth the label and eliminate or reduce air bubbles under the label. The hot air directed to the label 82 softens the label and contracts the label. The simultaneous application of heat and pressure from the air knife slot 84a84b to the label forces the label 82 to conform to the surface of the package 81, including the composite curves of the package. An optional subsequent heating step can be used to further contract the label. An advantage of this method is that there is no direct contact with the label so that surface imperfections are very likely not to be imparted to the label. One advantage is the ability to obtain high speed processing due to the excellent heat transfer to the label and the continuous heat recovery of the air knife assembly. This method can be used to apply the labels to a variety of container and article forms without the need for retrofitting.

Figure 9 illustrates an embodiment wherein multiple air knife slots and / or air knife assemblies are used to apply a label to a package or article in a sequence of steps. A label can be applied to one or both sides of the container. For simplicity of illustration, a label applies only to a surface of the package of Figure 9. The hot air knife assembly includes a source of hot air, a flow control mechanism and one or more hot air knife slots. . In an initial stage shown in Fig. 9A, a hot air knife slot 94 directs the hot air at a high velocity to the central region 93c of the label 92. The label 92 first applies to the central region 93c of the container 91. with a standard release tip distribution process (not shown) with the leading edge (first edge 93a) and back edge (second edge 93b) not adhered. The container with the label attached to it is transported to the air knife assembly via a conveyor. As shown in Figure 9B, while the container 91 is transported by the conveyor past the air knife slot 94, the hot air is forced against the label 92 to the first edge 93a of the label, heating the label and making it adapt to the surface of the container 91, while the second edge 93b is not adapted and / or adhered. The package is then rotated approximately 180 ° as shown in Figure 9C. As shown in Figure 9D, the container 91 with the label 92 adhered thereto is then transported to a second hot air slot 95 which forces the hot air against the label 92 from the center 93c to the second edge 93b of the label , heating the label and making it adapt to the surface of the container 91 as shown in Figure 9E. Depending on the size and configuration of the package, the hot air knife slots and / or additional hot air mounts can be used to apply heat and pressure to the label. An optional subsequent heating step can be used to further contract the label.

The labeled article of the present invention can be used in a variety of applications, including, but not limited to, personal care products, household chemicals, food and beverages, toys, electronic devices, pharmaceuticals, health care products, industrial products and accessories.

Examples The following examples are intended to illustrate only the methods and embodiments according to the invention, and as such should not be construed as limitations imposed on the claims.

Example 1 A pressure sensitive shrink label is constructed from a 3 mil (0.0762 mm) thick multi-layer, low density polyethylene shrink film designated as Sealed Air CorrTuff. The film is coated with an acrylic emulsion adhesive S692N from Avery Dennison. The adhesive is placed on a removable paper liner coated with GlassineBG-40 silicone. The label is Large size with dimensions of approximately 5 x 3.5 inches (1.27 mm x 88.9 mm), which is 20% larger than the recommended industrial standard label size for the bottle to which the label is applied.

A 15 ounce bottle (443.6 mi) of Johnson & Johnson Baby Lotion that has compound curves is filled with water, capped and processed through a 9000 Label-Aire series labeller at 100 bottles per minute (BPM). The labeler has dual feed screws with top and bottom speed belts matched with Label-Aaire 2115-CD labeling heads with high torque step motorized drive. The labels are compressed with an oscillating beam type rubbing device of the apparatus that provides direct central external forces to direct the trapped air below the label and the resulting crease / pleat defects to the edge of the label. The large label in relation to the bottle initially gives rise to small defects of unacceptable pleats and pleats around the perimeter of the label. The labeled bottle is then processed through a Leister hot air conveyor rubbing system at 100 bpm. High-temperature hot air at 260 ° C heats the bottle and the label at 50 ° C, contracting and taking the creases and pleats of excessive label material under the label to the surface of the bottle. The label is pressed with an oscillating beam for a good contact of the label. The folds contract and flatten easily after the application of heat.

The labeled bottle finished with a larger label area and a larger content of graphics is gently rubbed without flaws of creases, pleats, ridges or wrinkles present on the oversized labels sensitive to common pressure. The folds reoccur after the passage of time Table 1 below shows the characteristics of the label components.

Example 2 According to the process described in example 1, a pressure-sensitive shrinkage label constructed of a shrink film of polypropylene multilayer of 2 mils (0.0508 mm) thick designated as CZPA 200 by Innovia, is applied to the bottle that has compound curves. After initial rubbing, medium-sized folds are formed. The high-speed hot air heats the bottle and the label at 100 ° C. The folds contract and flatten easily rubbing after the application of heat. The folds reoccur after the passage of time.

Example 3 According to the process described in Example 1, a pressure-sensitive shrinkage label constructed from a shrink film of a single layer of polylactic acid of 2 mils (0.0508 mm) in thickness designated as EARTHFIRST PLA from Plástic Suppliersse applies to the bottle that has compound curves. After initial rubbing, medium-sized folds are formed. The high-speed hot air heats the bottle and the label at 70 ° C. The folds contract and flatten easily after the application of heat. The folds do not regenerate after the passage of time.

Comparative example 4 In accordance with the process described in example 1, a pressure-sensitive shrinkage label constructed from a single-layer shrinkable film of polypropylene oriented in the machine direction of 2 mils (0.0508 mm) thick from Avery Dennison is applies to the bottle what has compound curves. The high-speed hot air heats the bottle and the label at 70 ° C. The folds formed in the cap and at the bottom of the label contract during the application of heat and flatten easily, while the folds formed at the front and rear edges remain. The folds eliminated will not generate again during the course of time.

Comparative example 5 In accordance with the process described in example 1, a pressure-sensitive shrinkage label constructed from a single layer polyvinyl chloride film oriented in the transverse direction of 1.9 mils (0.04826 mm) of Thickness designated as Penta Labelde Kloeckner, is applied to the bottle that has compound curves. The high-speed hot air heats the bottle and the label at 60 ° C. The folds formed at the front and back edges of the label contract during the application of heat and flatten easily, while the folds formed at the top and bottom of the label remain. The eliminated folds do not re-generate during the course of time.

Comparative example 6 According to the process described in example 1, a pressure sensitive shrinkage label constructed from a single layer film of glycol-modified polyethylene terephthalate oriented in the transverse direction of 2 mils (0.0508 mm) thick designated as Fusion1775E Mitsubishi is applied to the bottle that has compound curves. The high-speed hot air heats the bottle and the label at 50 ° C. The folds formed at the front and back edges of the label contract during the application of heat and flatten easily, while the folds formed at the top and bottom of the label remain. The eliminated folds do not re-generate during the course of time.

Comparative example 7 According to the process described in example 1, a pressure-sensitive shrinkage label constructed from a film of a Single layer of polyvinyl chloride oriented in machine direction of 1.4 mils (0.03556 mm) in thickness designated as MF-L243 / 01 by KIoechner, is applied to the bottle that has compound curves. The high-speed hot air heats the bottle and the label at 6 ° C. The film does not fit the package. The initial rubbing is insufficient with many folds formed in all directions. The folds and ridges remain after the application of heat and a second rubbing. The film exhibits an excessive backward contraction. Comparative example 8 According to the process described in example 1, a pressure-sensitive shrinkage label constructed from a polypropylene multilayer film of 2.0 mils (0.0508 mm) in thickness designated as Vifan BTNY is applied to the bottle having curves compound. The high-speed hot air heats the bottle and the label at 100 ° C. The formed folds do not contract completely at high temperature and do not flatten completely. The folds are generated again during the course of time.

Comparative example 9 According to the process described in Example 1, a pressure-sensitive shrinkage label constructed from a polyethylene multilayer film (MDPE) of average density of 3.4 mils (0.08636 mm) thick designated as PE 85 of Charter Films, applies to the bottle that has compound curves. The high-speed hot air heats the bottle and the label at 100 ° C. The formed folds do not contract completely at high temperature and they do not flatten completely. The folds are generated again during the course of time.

Table 1 Although the invention has been explained with reference to its preferred embodiments, it should be understood that various modifications thereof will become apparent to those skilled in the art through the reading of the specification. Therefore, it should be understood that the invention described herein is intended to cover modifications such as those found within the scope of the appended claims.

Claims (22)

1. A method for applying a label to an article, comprising: providing an article having a surface, comprising at least one composite curve; providing a label comprising (i) a heat shrinkable film having an inner surface and an outer surface; and (ii) to the pressure sensitive adhesive layer on the inner surface of the heat shrinkable film, wherein the label has a first edge and a contact region; contacting the adhesive layer in the contact region of the label with the article; apply heat and pressure simultaneously to the label in one direction from the contact region to the first edge such that the first edge of the label adheres to the article and the label contracts to conform to the composite curve of the article, wherein the heat and Pressure are applied by at least one hot air blade assembly comprising a heated air source, a flow control mechanism and one or more hot air blade slots.

2. The method of claim 1, wherein the tag comprises a center and a second edge opposite the first edge, and the contact region is near or in the center of the tag.

3. The method of claim 1, wherein the label comprises a second edge opposite the first edge and the contact region is near the second edge of the label.

4. The method of claim 2, wherein the hot air blade assembly comprises at least two hot air blade slots that rotate externally from the center of the label to the first and second edges to adhere the label to the article.

5. The method of claim 2, wherein a first hot air knife slot applies heat and pressure from the center of the label to the first edge of the label, and a second hot air knife slot applies heat and pressure from the center of the label to the second edge of the label. '

6. The method of claim 5, further comprising rotating the article about 180 ° prior to the application of heat and pressure by the second hot air knife slot to the label.

7. The method of any one of the preceding claims, wherein the label is provided with a release liner adhered to the adhesive layer, and the method further comprises separating the release liner from the label prior to contacting the label with the article.

8. The method of any of the claims above, where the label is heated to a temperature of at least 40 ° C.

9. The method of any of the preceding claims, wherein the heat shrinkable film comprises a film selected from polyester, polyolefin, polyvinyl chloride, polystyrene, polylactic acid, copolymers thereof and mixtures thereof.

10. The method of any of the preceding claims, wherein the heat shrinkable film comprises a polyolefin.

11. The method of any of the preceding claims, wherein the heat shrinkable film comprises a multilayer film having a base layer and at least one surface layer.

12. The method of any of the preceding claims, wherein the stiffness of the film is at least 5mN in the machine direction.

13. The method of any of the preceding claims, wherein the label additionally comprises a printing layer between the heat shrinkable film and the adhesive layer, wherein the heat shrinkable film is transparent.

14. The method of any of the preceding claims, wherein the label additionally comprises a printing layer on the outer surface of the film i contractable by heat.

15. The method of claim 14, wherein the label additionally comprises a protective layer covering the printing layer.

16. The method of any of the preceding claims, wherein the adhesive layer comprises an emulsion adhesive.

17. The method of any of the preceding claims, wherein the adhesive layer comprises a hot melt adhesive.

18. The method of any of the preceding claims, wherein the adhesive layer comprises a solvent-based adhesive.

19. The method of any of the preceding claims, wherein the pressure-sensitive adhesive layer is continuous.

20. The method of any of claims 1t18, wherein the pressure sensitive adhesive layer is patterned and the pattern substantially covers the inner surface of the film.

21. The method of any of the preceding claims, wherein the heat shrinkable film has a machine direction and a transverse direction, the film has a main shrinkage S in at least one direction of at least 10% at 90 ° C, where the contraction in the other direction is S ± 20%.

22. The method of any one of the preceding claims, further comprising heating the label after the simultaneous application of heat and pressure to the label by mounting the hot air knife.