Patent Grant
11426923
The present invention relates to a method of activating the shrink characteristic of a multi-layered film, and a method for manufacturing a sleeved product.
Shrinkable films are commonly used to label products such as plastic containers or glass bottles.
Examples of products labelled with shrinkable films include detergent bottles, milk and yoghurt containers, jam jars and medicine bottles.
Shrinkable films, and in particular heat-shrinkable films, are designed to contract or shrink when heated and, in doing so, substantially conform to the shape of the product the film is being used to label.
It is known to activate the shrink characteristic of a heat-shrinkable film using steam and/or hot air, for example, by carrying the label and product through a tunnel provided with steam and/or hot air. US 2008/0197540 A1 for example discloses a multi-layered film that may be shrunk around an item in a heat tunnel using steam or hot air. However, there are some disadvantages associated with using hot steam and/or hot air to label products. For example, the hot steam and/or air may undesirably heat a substance contained within the product. Also, labels shrunk using hot steam and/or air often do not conform completely to all of the contours of the product, especially if the product has a complex shape.
It is also known to use UV light to shrink shrinkable films. Such films typically comprise a material that is capable of absorbing UV light. When the material absorbs the UV-light, heat may be generated and it is this generated heat that causes the shrinkable film to contract. US 2005/0142313 A1 for instance discloses a method of shrinking a film that comprises the steps of providing a shrink film and exposing the film to an amount of radiation energy effective to activate the shrink characteristics of the film. The film comprises single-walled carbon nanotube material as photothermic material. The effective amount of radiation energy may for instance comprise one or more of any of visible light, infrared light, ultraviolet light, microwave and radio wave.
Typical UV-emitting devices are known from US 2007/0235689 A1, US 2007/006924 A1, U.S. Pat. No. 4,859,903, EP 1067166 A2, and US 2006/0138387 A1.
The present invention is directed towards an improved method of activating the shrink characteristic of a multi-layered film.
The present invention provides a method of activating the shrink characteristic of a multi-layered film, the method comprising the steps of: providing a multi-layered film comprising at least a base layer film that comprises a shrinkable film, and a photothermic layer, associated with the base layer film, and comprising a photothermic material, exposing the multi-layered film to electromagnetic radiation in order for the photothermic material to shrink the multi-layered film; wherein the electromagnetic radiation comprises UV-light having a peak wavelength between 200 nm and 399 nm, and at least 90% of the UV-light is within a bandwidth of ±30 nm of the peak wavelength.
This method has the advantage of providing improved shrinkage of the multi-layered film. For example, the method produces more homogenous shrinkage of the multi-layered film.
The method of the present invention involves exposing the film to UV light, where at least 90% of the UV-light that falls within ±30 nm of the peak wavelength. This means that 90% of all of the UV radiation used falls within a 60 nm range.
If the intensity of the UV light used in the method of the present invention was to be plotted on a graph against the wavelength of the UV light, there would be a peak on this graph for the peak wavelength. In addition, at least 90% of the total intensity of the UV light would fall within ±30 nm of this peak on the graph.
In some embodiments of the invention, the photothermic layer comprises a white pigment suitable for absorbing UV light (for example, titanium dioxide). For example, the photothermic layer may be formed by printing an ink comprising the white pigment on to a base layer film. Alternatively, the photothermic layer may be formed by printing transparent lacquer comprising a UV absorber, such as a benzotriazole that is capable of absorbing UV light. Again, a transparent lacquer composition comprising said UV absorber may be printed onto the base layer film.
In other embodiments, the photothermic layer may comprise both a transparent lacquer composition, comprising a UV absorber, and an ink composition (comprising a white pigment). For example, if the multi-layered film also comprises a design layer and the photothermic layer is provided on top of this design layer, the photothermic layer may be formed from a transparent lacquer, and a white ink composition may be provided below the design layer at its back side in order to increase the contrast and brilliance of the design layer.
In some embodiments at least 90% of the UV-light is within a bandwidth of ±10 nm of the peak wavelength.
In preferred embodiment of the invention, the electromagnetic radiation may comprise UV-light having a peak wavelength of 365 nm, or 385 nm, or 395 nm, wherein at least 75% of the UV-light is within a bandwidth of ±10 nm of the peak wavelength.
In a more preferred embodiment, the electromagnetic radiation may comprise UV-light having a peak wavelength of 365 nm or 385 nm, wherein at least 90% of the UV-light is within a bandwidth of 10 nm of the peak wavelength.
Preferably, the UV-light is emitted by a LED-UV emitter.
The UV-light preferably has a peak wavelength between 300 nm and 395 nm, more preferably between 350 nm and 390 nm. For example, the peak wavelength may be 365 nm, 385 nm or 395 nm, with 365 nm and 385 being preferred.
In preferred embodiments of the invention, the base layer film is substantially free from a photothermic material. The base layer film may be a multi-layered laminated base layer film. Preferably, the base film comprises over 95% of a thermoplastic resin.
With ‘substantially’ is meant in the context of the present application at least 90% of the indicated quantity, more preferably at least 95% of the indicated quantity, and most preferably at least 98% of the indicated quantity.
In embodiments of the invention, the photothermic layer may be provided in direct contact with the base layer film. However, in other embodiments, the photothermic layer may be provided in indirect contact with the base film. For example, the photothermic layer may contact the base film via an intermediate design layer.
Preferably, the multi-layered film has a UV absorption of at least 50%, calculated from transmittance and reflectance as measured by ISO13468-2. The photothermic layer preferably has a UV absorption of at least 50%, more preferably of at least 60%, most preferably of at least 70%, calculated from transmittance and reflectance as measured by ISO13468-2.
In some embodiments of the invention, the photothermic layer is multi-layered and at least one of the photothermic layers has a UV absorption of at least 50%, calculated from transmittance and reflectance as measured by ISO13468-2.
Preferably, the multi-layered film comprises a design layer, associated with the base layer film and/or the photo-thermic layer, and comprising a colored ink composition. In some embodiments of the invention, the design layer may be the photothermic layer.
Preferably, the design layer is continuous with the base layer film and/or the photothermic layer. However, in some embodiments, the design layer may form a pattern of discontinuous regions, and the multilayer film comprising the base layer, the photothermic layer and the design layer is substantially homogeneously shrunk independent from the pattern. In this context, ‘substantially’ means at least 90% of the base layer film is shrunk independent from the pattern. The photothermic layer may be discontinuous but is preferably continuous.
Preferably, the photothermic layer and/or the design layer is printed. A photothermic layer may be formed typically by coating the base layer film, comprising the shrink film with a printing ink. Coating of the base layer film is performed by a known or common printing technique. The printing technique may be a common technique and is preferably selected typically from gravure printing and flexographic printing. The photothermic ink printed to form the photothermic layer may comprise but is not limited to a photothermic material, a binder resin, a solvent, and other additives. The solvent is typically evaporated at least partly after deposition of the ink on to the base layer film. This yields a photothermic composition on the base layer film, which photothermic composition then comprises a binder resin, the photothermic material and the other additives. The solvent may be selected from solvents generally used in printing inks, which are exemplified by organic solvents such as toluene, xylenes, methyl ethyl ketone, ethyl acetate, methyl alcohol, ethyl alcohol, and isopropyl alcohol, and water.
The binder resin for use herein is exemplified by, but not limited to, acrylic resins, urethane resins, polyamide resins, vinyl chloride-vinyl acetate copolymer resins, cellulosic resins, and nitrocellulose resins.
The photothermic material comprises a UV-light absorbing material selected from (white) titanium dioxide (TiO2); (black) carbon black; (cyan) phtalocyanide; (magenta) quinacridone, diketopyrrolopyrrole, naphtol-based azo pigment, anthraquinone; (yellow) aceto acetic acid- and/or anhydride-based azo pigment; dioxiazine and benzotriazole UV absorber; and combinations thereof. Each of the photothermic materials, binder resins, and solvents may be used alone or in combination in each category.
In the photothermic composition, a white ink composition comprising titanium dioxide is preferred. When a clear based design is required, a transparent lacquer composition comprising a UV absorber is preferably used as the photothermic composition.
The thickness of the photothermic layer may be selected within wide ranges since the thickness is not particularly critical. A thickness of the photothermic layer of from 0.1 to 10 μm is particularly preferred however.
A design layer in accordance with some embodiments of the invention is defined as a layer that indicates an item such as a trade name, an illustration, handling precautions, and the like. The design layer may be formed typically by coating the shrink film with a colored ink. The coating is performed by a known or common printing technique, and is preferably selected from gravure printing and flexographic printing. The colored ink printed to form the design layer may comprise but is not limited to a photothermic material, a binder resin, a solvent, and other additives. The binder resin for use herein is exemplified by, but not limited to, acrylic resins, urethane resins, polyamide resins, vinyl chloride-vinyl acetate copolymer resins, cellulosic resins, and nitrocellulose resins. Suitable pigments to be used in the design layer include but are not limited to white pigments, such as titanium oxide (titanium dioxide); indigo blue pigments, such as copper phthalocyanine blue; and other coloring pigments such as carbon black, aluminum flake, and mica. These pigments may be selected and used according to an intended purpose. The pigment may also be selected from extender pigments, typically used for gloss adjustment. Suitable extender pigments include but are not limited to alumina, calcium carbonate, barium sulfate, silica, and acrylic beads. The pigment may work as photothermic material. The level of potency is different depending on the pigment. The solvent may be selected from solvents generally used in inks, which are exemplified by organic solvents such as toluene, xylenes, methyl ethyl ketone, ethyl acetate, methyl alcohol, ethyl alcohol, and isopropyl alcohol, and water. Each of such pigments, binder resins, and solvents may be used alone or in combination in each category.
The design layer may have any thickness which is not critical, but preferably ranges from 0.1 to 10 μm.
The base layer film in accordance with the invention comprises a shrinkable film. The shrinkable film for use in the method comprises a layer that serves as a base of the label and which bears strength properties and shrinking properties. One or more thermoplastic resins for use in the shrinkable film may be suitably selected typically according to required properties and cost. Exemplary resins include, but are not limited to, polyester resins, olefinic resins, styrenic resins, poly(vinyl chloride)s, polyamide resins, and acrylic resins. The shrinkable film is preferably made from a polyester film, a polystyrenic film, or a multilayered laminated film of these films. Exemplary polyester resins usable herein include poly(ethylene terephthalate) (PET) resins, poly(ethylene-2,6-naphthalenedicarboxylate)s (PENs), and poly(lactic acid)s (PLAs), of which polyethylene terephthalate) (PET) resins are preferred. Preferred exemplary styrenic resins include regular polystyrenes, styrene-butadiene copolymers (SBSs), and styrene-butadiene-isoprene copolymers (SBISs).
The shrinkable film for use herein may be a single-layer film, or a multilayered laminated film including two or more film layers according typically to required properties and intended use. When use is made of a multilayered laminated film, the multilayered laminated film may include two or more different film layers made from two or more different resins, respectively.
The shrinkable film is preferably a monoaxially, biaxially, or multiaxially oriented film, so as to exhibit shrinking properties. When the shrinkable film is a multilayered laminated film including two or more film layers, at least one film layer of the multilayered laminated film is preferably oriented. When all the film layers are not or only slightly oriented, the shrinkable film may not exhibit sufficient shrinkage properties. The shrinkable film is preferably a monoaxially or biaxially oriented film and is even more preferably a film substantially oriented in a transverse direction or in a machine direction of the film. In other words, the shrinkable film is preferably oriented substantially monoaxially in a transverse direction or in a machine direction. This direction of main orientation will preferably coincide with a circumferential direction of a sleeve or ROSO label.
The shrinkable film may be prepared according to a common procedure such as film formation using a molten material or film formation using a solution. Independently, commercially available shrinkable films are also usable herein. Where necessary, the surface of the shrinkable film may have been subjected to a common surface treatment such as corona discharge treatment and/or primer treatment. The lamination of the shrinkable film, in case of a laminated structure, may be performed according to a common procedure such as coextrusion or dry lamination. Orientation of the shrinkable film may be performed by biaxial drawing in a machine direction (MD) and in a transverse direction (TD) or by monoaxial drawing in a machine or transverse direction. The drawing can be performed according to any of roll drawing, tenter drawing, or tube drawing. The drawing is often performed by conducting drawing in a machine direction according to necessity and thereafter drawing in a transverse direction each at a temperature of from about 70° C. to about 100° C. The draw ratio in the machine drawing may be from about 1.01 to about 1.5 times, and preferably from about 1.05 to about 1.3 times. The draw ratio in the transverse drawing may be from about 3 to about 8 times, and preferably from about 4 to about 7 times.
Though not critical, the thickness of the shrinkable film is preferably from 10 to 100 μm, more preferably from 20 to 80 μm, and even more preferably from 20 to 60 μm. The shrinkable film may be a three-layer film including a core layer and surface layers. In this case, the ratio in thickness among the core layer and the surface layers [(surface layer)/(core layer)/(surface layer)] is preferably from 1/2/1 to 1/10/1. In case a five-layer shrinkable film is used, the ratio in thickness among the core layer and the surface layers [(surface layer)/(core layer)/(surface layer) is preferably from 1/0.5 to 2/2 to 10/0.5 to 2/1.
The shrinkable film may be shrunk or may not be shrunk in UV light without the photothermic layer. The shrinkable film can be shrunk well to combine to a photothermic layer. The percentage of shrinkage in UV light of 6.0 J/cm2 (such as obtained by UV light of a wavelength of 365 nm at 3.3 W/cm2, or a wavelength of 385 nm at 5.5 W/cm2) of the shrinkable film in its main direction of orientation is preferably less than 5%. Although not critical, the percentage of thermal shrinkage of the shrinkable film in its main direction of orientation is preferably less than 10% in hot water at 60° C. for 10 seconds, more preferably less than 10% in hot water at 70° C. for 10 seconds, even more preferably less than 10% in hot water at 80° C. for 10 seconds, and most preferably less than 10% in hot water at 90° C. for 10 seconds. When the shrinkable film has a percentage of thermal shrinkage in its main orientation direction exceeding the above preferred ranges, the stability of storage is higher and the risk to shrink unnecessarily during transportation is reduced. A further advantage of the present embodiments is represented by a limited or even non-existing shrinkage at atmospheric temperatures during transportation, Although not critical, the percentage of thermal shrinkage in a hot glycerin bath at 150° C. for 10 seconds of the shrinkable film in its main direction of orientation is preferably at least 30%. From the viewpoint of accessibility, a shrinkable film having at least 40% of thermal shrinkage in hot water at 90° C. for 10 seconds can also be chosen.
The percentage of shrinkage in UV light of 6.0 J/cm2 (such as obtained by UV light of a wavelength of 365 nm at 3.3 W/cm2, or a wavelength of 385 nm at 5.5 W/cm2) of the base layer film in its main direction of orientation is preferably less than 5%. Although not critical, the percentage of thermal shrinkage of the base layer film in its main direction of orientation is preferably less than 10% in hot water at 60° C. for 10 seconds, more preferably less than 10% in hot water at 70° C. for 10 seconds, even more preferably less than 10% in hot water at 80° C. for 10 seconds, and most preferably less than 10% in hot water at 90° C. for 10 seconds. When the base layer film has a percentage of thermal shrinkage in its main orientation direction exceeding the above preferred ranges, the stability of storage is higher and the risk to shrink unnecessarily during transportation is reduced.
Although not critical, the percentage of thermal shrinkage in hot glycerin bath at 150° C. for 10 seconds of the base layer film in its main direction of orientation is preferably at least 30%. In point view of accessibility, the base layer film having at least 40% of thermal shrinkage in hot water at 90° C. for 10 seconds also can be chosen.
The percentage of shrinkage of the multi-layer film in its main direction of direction, as obtained by exposure to UV light of 6.0 J/cm2 (such as obtained by UV light of a wavelength of 365 nm at 3.3 W/cm2, or a wavelength of 385 nm at 5.5 W/cm2), is preferably at least 15%, more preferably from 30% to 80%, and even more preferably from 50% to 80%. This embodiment yields a higher total shrinkage after the shrinkage treatment, which is beneficial in sleeving irregularly shaped containers or bottles. When the multilayer film has a percentage of shrinkage by UV light in its main orientation direction exceeding the above preferred ranges, the film when shrunk conforms substantially completely to substantially all contours of the product to be sleeved, in particular when the product has a complex shape.
Although not critical, the percentage of thermal shrinkage of the multi-layer film in its main direction of orientation is preferably less than 10% in hot water at 60° C. for 10 seconds, more preferably less than 10% in hot water at 70° C. for 10 seconds, even more preferably less than 10% in hot water at 80° C. for 10 seconds, and most preferably less than 10% in hot water at 90° C. for 10 seconds. When the multi-layer film has a percentage of thermal shrinkage in its main orientation direction exceeding the above preferred ranges, the stability of storage is higher and the risk to shrink unnecessarily during transportation is reduced.
Although not critical, the percentage of thermal shrinkage in hot glycerin bath at 150° C. for 10 seconds of the multi-layer film in its main direction of orientation is preferably at least 30%. From the point of view of accessibility, a multi-layer film having at least 40% of thermal shrinkage in hot water at 90° C. for 10 seconds can also be chosen.
As used herein the term “main orientation direction” refers to a direction in which the drawing process of the shrinkage film has been mainly performed (i.e., a direction in which the percentage of thermal shrinkage is largest) and, when the shrinkable label is a tubular shrinkable label, the main orientation direction will generally be in a width direction of the film.
The percentage of shrinkage of the multi-layered film in a direction perpendicular to the main orientation direction by exposure to UV light of 6.0 J/cm2 (365 nm at 3.3 W/cm2; or 385 nm at 5.5 W/cm2) is preferably from about −10% to about 50%, more preferably from −10% to 20%, and most preferably from −5% to 10%, or from −5% to 3%, although these percentage are not critical.
The transparency of the shrinkable film for use in embodiments wherein the shrinkable film is a transparent film, is preferably less than 15.0, more preferably less than 10.0, and most preferably less than 5.0, in terms of haze (%) determined in accordance with ISO14782. The shrinkable film, when having a haze of 15 or more, may cloud a print and thereby cause insufficient decorativeness when the print is to be seen through the shrinkable film. If the haze of the shrinkable film is within the preferred ranges, it may be possible in some embodiments to print on the backside.
In some embodiments, the base layer film may have a stretch ratio (ST ratio) of at least three in one or more directions.
The multi-layer film preferably has a UV shrinkage of at least 15% in main shrinking direction as obtained by exposure to UV light of 6.0 J/cm2.
The base layer film preferably has a UV shrinkage of less than 5% in main shrinking direction as obtained by exposure to UV light of 6.0 J/cm2.
The base layer film has a free shrink in main shrinking direction of less than 10% after immersion in water at 60° C. for 10 sec.
In some embodiments, the photothermic layer may comprise a photothermic composition comprising one or more binder resins and from 3 to 80 wt. % of the photothermic material relative to the weight of the photothermic layer.
The photothermic material may comprise UV-light absorbing material selected from (white) titanium dioxide (TiO2); (black) carbon black; (cyan) phtalocyanide; (magenta) quinacridone, diketopyrrolopyrrole, naphtol-based azo pigment, anthraquinone; (yellow) aceto acetic acid- and/or anhydride-based azo pigment; dioxiazine and benzotriazole UV absorber, benzo triazole, benzophenone, salicylate, triazine and/or cyano acrylate type of UV absorbers; and combinations thereof.
In embodiments of the invention, the photothermic composition of the photothermic layer may comprise a white ink composition, comprising from 20 to 80 wt. % of titanium dioxide relative to the weight of the photothermic layer. Alternatively or additionally, the photothermic composition of the photothermic layer may comprise a transparent lacquer composition comprising a benzotriazol UV absorber.
Exemplary UV absorbers or organic photothermic materials include compounds in the benzophenone type of UV absorbers, such as 2-Hydroxy-4-methoxy benzophenone (e.g., Cyasorb UV 9) and 2-hydroxy-4-octoxy benzophenone (e.g., Cyasorb 531 and CibaR CHIMASSORBR 81). Other exemplary UV absorbers include compounds in the benzotriazole type of UV absorbers, such as 2-(2′-hydroxy-3′-tert-butyl-5′-methylphenyl)-5-chlorobenzotriazole, 2-(2H-hydroxy-3-5-Di-tert-amyllphenyl)benzotriazole, 2-2-hydroxy-5-tert-octylphenyl) benzotriazole, 2-(2H-hydroxy-3-5-di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-5-methyl phenyl) benzotriazole, and 2-[2-hydroxy-3,5-di-(1,1-dimethylbenzyl)phenyl]-2H-benzotriazole. Yet other exemplary UV absorbers include p-aminobenzoic acid (PABA), avobenzone, 3-benzylidene camphor, benzylidene camphor sulfonic acid, bisymidazylate, camphor benzalkonium methosulfate, cinoxate, diethylamino hydroxybenzoyl hexyl benzoate, diethylhexyl butamido triazone, dimethicodiethylbenzal malonate (Parsol SLX), dioxybenzone, drometrizole trisiloxane, ecamsule, ensulizole, homosalate, isoamyl p-methoxycinnamate, 4-methylbenzylidene camphor, menthyl anthranilate, octocrylene, octyl dimethyl PABA, octyl methoxycinnamate, octyl salicylate, octyl triazone, oxybenzone, PEG-25 PABA, polyacrylamidomethyl benzylidene camphor, sulisobenzone, bisethylhexyloxyphenol methoxyphenol triazine (e.g., Tinosorb S), methylene bis-benzotriazolyl tetramethylbutylphenol (e.g., Tinosorb M), and trolamine salicylate.
According to a second aspect of the present invention there is a method for manufacturing a sleeved product, the method comprising arranging a sleeve around the product, the sleeve comprising a multi-layered film comprising at least a base layer film comprising a shrinkable film, and a photothermic layer, associated with the base layer film, and comprising a photo-thermic material, exposing the sleeve to electromagnetic radiation in order for the photothermic material to shrink the multi-layered film; wherein the electromagnetic radiation comprises UV-light having a peak wavelength between 200 nm and 399 nm, and at least 90% of the UV-light is within a bandwidth of ±30 nm of the peak wavelength.
Preferably, the sleeve is provided in a flat form and wrapped around a mandrel, whereby two sleeve edge parts to be sealed overlap and/or contact each other in a seam area, and the edges are sealed to provide a tubular sleeve, whereafter the sleeve is opened and ejected around the product.
The sleeve is preferably provided in a flat form and wrapped around the product whereby two sleeve edge parts to be sealed overlap and/or contact each other in a seam area, and the edges are sealed to provide the sleeve. Alternatively, the sleeve may be provided in a preformed tubular form and arranged around the product.
Preferably, at least one of the edge parts does not comprise the photothermic layer in the seam area. This provides reduced shrinkage of the film in the seam area and results in stronger bonding strength between the edge parts.
In some embodiments, the product may have a substantially cylindrical shape comprising a large diameter part and a smaller diameter part, and the sleeve covers at least part of the large diameter and smaller diameter part. In these embodiments, the circumference of the smaller diameter part may be between 15-70% of the circumference of the large diameter part.
The accompanying figures are used to illustrate non-limiting exemplary embodiments of the present invention.
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The sleeve 41 may be provided in a preformed tubular form, the sleeve 41 being cut from an elongated preformed sleeve 410 of the multi-layered film (1, 10) at a pitch 43 in a transverse direction 42 to the axis of the sleeve 41. The circumferential direction of the sleeve 410 corresponds to the main orientation and main shrinkage direction.
In an alternative embodiment, the sleeve 41 is provided in the form of a flat film 50 and a piece of the flat film 50 is cut in a transverse direction 53 to a longitudinal axis of the flat film 50, and then wrapped around a cylindrical mandrel 51 that is rotated in a circumferential direction 52 of the mandrel 51. An edge part of the cut flat film 50 is provided with a strip of adhesive 54 which bonds two overlapping edge parts of the flat film 50 to provide the tubular sleeve 41. A machine direction of the flat film 50 corresponds to the main shrinkage and circumferential direction 52.
To arrange the sleeve 41 around the bottle 39, the sleeve 41 is slightly opened and ejected around the bottle 39 in a direction 55. The sleeve 41 is then exposed to electromagnetic radiation emitted by a plurality of UV LED sources 44, which move relative to the sleeved bottle (39, 40). The relative movement may be achieved by moving the sleeved bottle (39,40) and/or by moving the UV light sources 44, for instance in a circular spinning movement.
As shown in
UV devices suitable for producing the UV light required for embodiments of the invention include UV-LED lamps with the item code FE300 produced by Phoseon Technology. Details of three FE300 UV-LED lamps with peak wavelengths of 365 nm, 385 nm and 395 nm are outlined in Table 1 below.
According to the invention, a UV-light source having a peak wavelength between 200 nm and 399 nm is used, whereby at least 90% of the UV-light is within a bandwidth of ±30 nm of the peak wavelength. A UV-light emitter having the claimed narrow wavelength distribution may be used, but it is also possible to use a UV light source having a wider wavelength distribution and filtering the light to obtain the claimed narrow wavelength distribution.
Although the power of the UV-light source may be varied within a large range, a preferred power of the UV-light source ranges from 0.5-100 W/cm2, more preferably from 1-30 W/cm2, and most preferably from 3-20 W/cm2. Suitable UV-light emitters are for instance FE300 (365 nm): 3.3 W/cm2, and FE300 (385 nm): 5.5 W/cm2.
The preferred UV LED devices may use any tip disposition, and one line type UV LED emitters such as FE300 (Phoseon), and/or multi line type UV LED emitters such as FJ 100 (Phoseon) may be used.
Preferred lenses may have any shape and comprise rod lenses and flat lenses, whereby a rod lens is more preferred than a flat lens in order to keep the irradiation power at an even distance from the light source. The distance between the UV-light source and the product surface to be irradiated may be varied but is preferably close enough to prevent a large reduction of the irradiation power, which typically reduces with distance. A preferred distance between a product surface to be irradiated and a UV-light source is <75 mm, more preferably <50 mm, even more preferably <30 mm, and most preferably <20 mm.
The product may be irradiated by the UV-light source in a device that allows irradiation of substantially the complete product surface once, or a few times. Preferably, a sleeved product that needs to be irradiated is moved relative to the UV-light source or sources. Movement may be achieved in any conceivable way, such as by hoisting or spinning a product and/or UV-light source, or a line or multi line of UV-light sources or sleeved products.
In addition, for comparison, Table 1 also details an electrodeless lamp produced by Heraeus Noblelight. This lamp does not produce the UV-light required for the method of activating the shrink characteristic of a multi-layered film of the present invention.
Tables 2 to 5 below detail the distribution of relative radiance of each of the lamps listed in Table 1.
As can be seen from Tables 1 to 5, the lamps produced by Phoseon Technology all produce UV-light that is within ±30 nm of the peak wavelength.
Base Layer
The multi-layer films that are configured to be shrunk on the application of heat comprise a base layer. The base layer film of the multi-layered film comprises a shrinkable film, and preferably comprises over 95% of thermoplastic resin. Suitable types of base layer are detailed in Table 6 below. Their heat shrinkage in TD is shown in the Table 6.
The heat shrink ratio of the APET and BOPP films of Table 6 at 130° C. for 2 min is APET: 34%, and BOPP: 3%.
Photothermic and Design Layers
Shrinkable films adapted to be shrunk may also comprise ink in a photothermic layer and/or a design layer. Examples of such inks are listed in Table 7.
These inks may be printed onto another layer of the film, for example the base layer film, using Gravure printing. The layers of printed ink may be 1.0 .mu.m thick. Titanium dioxide may be used in the white ink composition, for instance an amount of 50% by weight of the total white ink composition.
Alternatively, a photothermic layer may comprise a clear lacquer (i.e. a “clear lac”). Suitable lacquers include Lacquers B and C listed in Tables 8-1 and 8-2.
Shrink films (i.e. films that are configured to be shrunk) were prepared using a base layer selected from Table 6. In addition, a photothermic layer was applied to this base layer. This photothermic layer comprised one of the Flint inks listed in Table 7, or a clear lacquer selected from those listed in Table 8-2. These films form working examples I-1 to I-11 in Table 9 below.
Comparison examples I-1 to 1-7 listed in Table 9 comprise only a base layer (i.e. there is no photothermic layer). In comparison example I-8, the shrink film comprises Lacquer A in the printed layer. The printed Lacquer A does not comprise a photothermic material.
UV light was applied to these shrink films using one of the UV lamps described in Table 1. The percentage shrinkage of these films by the UV light was then measured and the results of these shrinkage experiments are given in Table 9.
In the multi-layer films of Table 9, there is no design layer.
In Example 2, multi-layer films were prepared from a base layer, a photothermic layer and a design layer. Details of these multi-layer shrink films are listed in Table 10.
The base layer was selected from those examples listed in Table 6, the photothermic layer comprises the white Flint ink listed in Table 7, and the design layer comprises additional flint inks of Table 7.
UV light was applied to the films using one of the UV lamps listed in Table 1. The shrinkage of the multi-layer films of Example 2 was measured and the results are listed in Table 10.
The working examples II-2, 4, 5 and the comparative example II-1 have a continuous backing white on design layer that is printed with a number of color inks (cyan, magenta, black, yellow) to eliminate overlap with each design ink below a base layer.
In working example II-3 a continuous transparent lacquer comprising photothermic material shown as lacquer B in table 8 is printed on top of a base layer film together with a number of color inks (cyan, magenta, black, and yellow) to eliminate overlap with each design ink on the other side of the base layer film, meaning below the base layer film.
When any color is described as a design layer in the table, it means that the part does not have a design layer.
As with Example 2, the films of Example 3 comprise a base layer, a photothermic layer and a design layer. The multi-layer shrink films of Example 3 are listed in Table 11.
The results of experiments conducted on the films of Example 3 are given in Table 11. The top part of Table 11 discloses experiments on the indicated films, whereas the bottom part of Table 11 describes the results of the carousel and around shrink test performed on working examples II-4. II-1 and III-2.
Experiment to Analyze the Percentage of UV Absorption
In Examples 1, 2 and 3, the UV absorption was measured using a UV spectrometer of the type Shimadzu UV-VIS Recording spectrophotometer UV-2401PC. The UV absorption was calculated from transmittance and reflectance as measured using the standard ISO13468-2 (=JIS K 7361-2).
In Examples 1 to 3, the UV absorption of the multi-layer film and a part of multi-layer film or same formulations as the part of the multi-layer film was measured. Firstly, the transmittance and reflectance of the film were measured. Secondly, the UV absorption percentage was calculated using:
UV absorption %=100−(transmittance+reflectance)
In addition, the UV absorption of the photothermic layer was measured. This was achieved by: (1) Measuring the UV absorption of only the base layer film (2) Measuring the UV absorption of the photothermic layer and the base layer film (3) Calculating the UV absorption of the photothermic layer as follows:
UV absorption of the photothermic layers=(2)−(1)
A similar method was used to calculate the UV absorption of the design layer (if present).
Free Shrink Test
In the tables, the free shrinkage by light has also been measured.
In the method used to measure the free shrinkage, samples of the multi-layered films were first prepared. These samples each had dimensions of: 50 mm in the transverse direction (TD) 15 mm in the machine direction (MD).
Then: (1) Each sample was placed on a PET sheet that has not been treated with any coating. (2) Each sheet was then placed on a conveyer belt and passed under the UV light source in a constant condition. (3) The free shrinkage was then calculated using:
Shrinkage (%)=(L0-L1)/L0*100; with L0: Length of transverse direction before irradiation L1: Length of transverse direction after irradiation In addition, the appearance of the shrunken sample was checked and classified either A or B:
A—if there was an even shrink,
B—if there was an uneven shrink
In Examples 1 to 3, three samples of each example listed in the tables were used and the average value (i.e. the mean value) obtained from these three samples is given in the tables.
Carousel Shrink Test
In Example 3, a carousel shrink test was also performed. This test involved: (1) Preparing a lay-flat sample (a seamed tubular sleeve laid flat) that has a width of 72 mm and a cut height (or pitch) of 95 mm in size (2) The sample was then formed into a sleeve and arranged around a bottle so that a maximum shrinkage of 30% is required to fit the sleeve to the bottle (3) The bottle and sample were then placed in the middle of a set of six UV lights of type UV light II with a rod lens and spun around at 200 bpm (4) The sample was then irradiated with 7 J/cm of UV light II (5) After shrinking, the appearance was checked an classified as either A or B, where: A—indicates shrinking without concentration by colour influence B—indicates shrinking with concentration by colour influence.
Around Light Shrink Test
In Example 3, an around light shrink test was additionally performed. This test involved: (1) Preparing a lay-flat sample that is 72 mm by 95 mm in size (2) The sample was then formed into a sleeve and arranged around a bottle so that a maximum shrinkage of 30% is required to fit the sleeve to the bottle. (3) The bottle and sample were then placed in the middle of a set of four UV lights of type UV light II with a ROD lens. These four UV lights are arranged in a square configuration around the bottle. (4) The bottle was then moved vertically at a speed of 1 m/min through the middle of the square of UV lights so that the sample is irradiated at 24 J/cm2. (5) After shrinking, the appearance was checked and classified as for the carousel test.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014885 | May 2015 | NL | national |
This application is a continuation application of U.S. application Ser. No. 15/578,121, entitled “Method For Manufacturing A Sleeved Product,” filed on Nov. 29, 2017, which claims priority to PCT Application No. PCT/EP2016/061929, entitled “Method For Manufacturing A Sleeved Product,” filed on May 26, 2016, which claims priority to NL Application No. 2014885, entitled “Method For Manufacturing A Sleeved Product,” filed on May 29, 2015, the disclosures of which are incorporated by reference herein.
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| Number | Date | Country | |
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| 20210362400 A1 | Nov 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15578121 | US | |
| Child | 17393514 | US |
