Packaging system

Abstract

High speed case and carton sealing lines for packaging articles. The carton to be packaged, i.e., filled and sealed, having disposed thereon an adhesive comprising an energy-absorbing ingredient that is capable of absorbing and reflecting radiant energy. The automated packaging machine comprises a means to reactivate an adhesive to effect sealing.

Description

FIELD OF THE INVENTION

[0001] The invention relates to a packaging system, and more particularly to a packaging machine. The packaging machine is adapted to activate an adhesive applied to a carton blank prior to use by the packager in a packaging machine.

BACKGROUND OF THE INVENTION

[0002] Adhesives are widely used for various commercial applications. Hot melt adhesives, for example, are commonly used in product assembly and packaging applications, including cardboard case sealing and carton closing operations. Such hot melt adhesives are applied to a substrate while in its molten state and cooled to harden the adhesive layer.

[0003] In the conventional case and carton packaging process for food and consumer goods, the boxes are first filled with food or consumer goods, then a hot melt adhesive is applied to the flap of boxes on the packaging line and compression is exerted to seal the boxes. While this process works reasonably well, it requires the packaging company to devote a tremendous amount of time and attention to adhesive-related issues, including adhesive selection, processing, trouble-shooting, inventory, and maintenance of adhesive application equipment. First, selection of an adhesive having the required adhesion, setting speed, and open time is a lengthy process. Then the adhesive needs to be processed in an appropriate way such as melting, transporting, and applying. If anything is wrong with the processing, the boxes will not seal properly, the packaging line must be stopped, and the problem identified and fixed.

[0004] Re-activation or heat sealing of pre-applied adhesives is known and practiced in the art. Heat sealed closures and seams are commonly used in the manufacture of bags, whereby adhesive is coated on the inside of the bag seam and subsequently sandwiched under intense heat and pressure using heated platens or bars. This direct application of heat and pressure renders the adhesive molten, after which a bond is formed. This application benefits from the ability to apply steady direct pressure to ensure intimate contact and sufficient wetting of the adhesive layer to the substrate. This process cannot be used for applications where high pressure for closing is not available, such as in case and carton packaging processes. While focused hot air has been used in the reactivation of pre-applied adhesives used in case and carton sealing operations, this method requires extremely large amounts of energy and can result in undesired heating of the substrate or package, its contents, and the surrounding area and equipment. Moreover, line speed is slow.

[0005] A need exists in the art for a packaging system that can advantageously be used for case and carton sealing whereby the case or carton to be formed, filled and sealed is provided to the packager with adhesive already applied to the case or carton and later, during packaging, re-activated in order to close or seal the case or carton. The current invention addresses this need.

SUMMARY OF THE INVENTION

[0006] The invention provides a packaging machine adapted to reactivate an adhesive or sealant composition that has been previously applied to the case or carton.

[0007] One aspect of the invention is directed to a packaging machine adapted to activate an adhesive applied to a substrate by the package manufacturer, also referred to as the converter. Form, fill and seal packaging machines In a preferred embodiment the adhesive is activated upon exposure to short durations of radiant energy.

[0008] The packaging machine comprises a frame, a plurality of stations carried by the frame and a drive assembly. A conveying assembly is operably connected to the drive assembly for moving the cartons through the stations. Stations include a carton erection station, a filling station and a means for reactivating an adhesive present on at least a portion of a carton. Many packaging machines will also comprise a bottom flap sealing station and/or a top flap sealing station. If both bottom and top flaps are to be sealed, they may be sealed simultaneously or, alternatively, sequentially.

[0009] Another aspect of the invention relates to carton blanks including flat, folded carton blanks having applied on at least one substrate surface thereof an adhesive capable of being activated upon exposure to short durations of radiant energy. The adhesive applied to the case or carton comprises an effective amount of an energy-absorbing ingredient such that upon exposure of the adhesive to radiant energy, the adhesive is activated. The energy-absorbing ingredient selected for use may be dissolved and/or dispersed within the adhesive composition. Organic dyes and pigments are particularly useful energy-absorbing ingredients for use in the practice of the invention. Adhesives comprising carbon black and NIR absorbing dyes are particularly preferred for use in the practice of the invention. Upon exposure to radiant energy, the adhesive melts to the extent that it is capable of bonding the substrate surface to a second substrate surface.

[0010] Still another aspect of the invention is directed to an automated process for packaging a consumer good by forming, filling and, optionally sealing a container (e.g., a case or carton) that has had applied to at least a portion thereof a reactivatable adhesive comprising an energy-absorbing ingredient.

[0011] In preferred embodiments the adhesive is present on at least one top and/or at least one bottom flap. The method comprises obtaining a flat folded carton blank comprising an adhesive containing an energy absorbing ingredient, erecting or forming a tubular shaped packaging capsule, placing an object to be packaged in the tubular packaging capsule, irradiating the applied adhesive with radiant energy for a time sufficient to melt the adhesive, bringing one substrate (e.g., a first top or bottom flap) in contact with the melted adhesive on another substrate (e.g., a second top or bottom flap), and allowing the adhesive to solidify thereby bonding the first substrate (flap) to the second substrate (flap) and sealing the container. Optionally, pressure may also be applied to effect said closing. If the substrate is transparent or translucent to the energy used for reactivation, the container may be closed and then NIR energy can be applied to initiate cure.

[0012] In other embodiments, a container is formed by folding a packaging blank along pre-predetermined fold lines, reactivating adhesive present on predetermined areas of the packaging blank and sealing at least one portion of the packaging blank to a second portion of the packaging thereby forming the container. The article to be packaged may be inserted into the package either during the formation of the package, such as in conventional wrap-around packaging, or after, such as in conventional Bliss box packaging, tray formation, in the manufacture of boxes and bags.

[0013] Yet another aspect of the invention is directed to an automated process for packaging a consumer good by forming, filling and sealing a container (e.g., a case or carton) that has had applied to at least a portion thereof a reactivatable adhesive comprising an energy-absorbing ingredient. In preferred embodiments the adhesive is present on at least one top and at least one bottom flap. The method comprises irradiating the applied adhesive with radiant energy for a time sufficient to melt the adhesive, bringing one substrate (e.g., a first top or bottom flap) in contact with the melted adhesive on another substrate (e.g., a second top or bottom flap), and allowing the adhesive to solidify thereby bonding the first substrate (flap) to the second substrate (flap) and sealing the container. Optionally, pressure may also be applied to effect said closing. In the practice of the invention, exposure to radiant energy is typically for periods of less than about 5 seconds, more typically for a period of less than about 3 seconds. Pressure is typically applied for periods of less than about 30 seconds, more typically less than about 5 seconds. If the substrate is transparent or translucent to the energy used for reactivation, the adhesive formula may be sandwiched between substrates first, and then NIR energy can be applied to initiate cure.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0014] Drawing FIGS. 1-4 illustrate several types of packaging having adhesive pre-applied to the substrate surface thereof.

[0015] FIGS. 1 and 2 illustrate typical form, fill and seal embodiments of the invention.

[0016] FIG. 3 illustrates a typical Bliss box package.

[0017] FIG. 4 illustrates a typical wrap around package.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention is directed to a packaging system. The packaging system comprises a machine adapted for reactivation of an adhesive applied during the manufacture of a packaging substrate (e.g. a continuous web), a packaging blank (e.g., a carton blank), or the like comprising a reactivatable adhesive. Alternatively, the adhesive may be applied following the manufacture of the packaging blank but prior to use of the carton blank in the packaging of an article, e.g., a consumer good.

[0019] The packaging system provides an improvement over prior art packaging systems that require application of adhesive to a packaging blank at one or more gluing stations located within the packaging machine.

[0020] Packages or containers are used interchangeably herein and include cartons, cases, trays, bags, boxes and the like. I.e., anything used to package a consumer goods such as food and beverages, pharmaceuticals, cosmetics, breakfast cereals, beverage containers (e.g., beer bottles and the like), bakery items, dry foods (e.g., dog food), produce, household products, paper products, soaps and detergents, candy, wet food, frozen food, diapers and the like, and hard goods such as but not limited to tools, fasteners, automotive parts, and light bulbs.

[0021] While the term case is generally used in the art to refer to outer shipping containers typically made of corrugated paperboard and the term carton is generally used in the art to referr to a container typically manufactured from solid fiber (e.g., a cereal box), the invention will hereinafter refer generally to the manufacture of a “carton.” It is to be understood however that the invention is not to be so limited.

[0022] Reactivation, as this term is used herein, refers to an adhesive that resides on at least a portion of at least one substrate to be bonded. In the context of a hot melt adhesive, the adhesive has been applied to a substrate in the molten state and allowed to cool, i.e., solidify, thereon. The adhesive present on the substrate is thereafter reactivated or heated to a molten state, brought in contact with a second substrate and allowed to cool or solidify, thereby bonding the two substrates together. The application of the adhesive onto a substrate for later activation or “reactivation” is referred to herein, and in the art as a “pre-applied” adhesive.

[0023] The reactivation efficiency of an adhesive refers to the ability of the adhesive to reactive, e.g., become molten in a short period of time. Reactivation efficiency will depend on the power of the device and the distance of the energy source from the adhesive. Reactivation time depends on receptivity of the adhesive, which depends on the energy absorbing ingredient, the coating weight or thickness of the adhesive and the energy flux density that the radiant source can supply to the adhesive (e.g., intensity per unit area). Energy flux density refers to the distance, focal point, power and intensity of the lamp or power source.

[0024] Preferably, the reactivatable adhesives are formulated to reactivate to a temperature of at least about 200° F., more preferably to a temperature of at least about 250° F. upon exposure of less than about 1200 watts/sq inch of near infrared energy for a period of less that about 10 seconds, more preferably less than about 5 seconds, even more preferably less than about 3 seconds.

[0025] The adhesive compositions applied to the packaging substrate contains an energy absorbing ingredient that increases the absorption and reduces the transmission of radiant energy that creates a temperature distribution within the adhesive that optimizes performance. The adhesives have improved re-activation and performance properties after irradiation. The adhesives of the invention reactivate on exposure to short durations of radiant energy and provide superior on-line performance and set speed that allows for quicker production speeds.

[0026] The improved re-activation and performance may preferable be achieved by incorporating into an adhesive an energy-absorbing ingredient. Energy-absorbing ingredients include those dyes, pigments, fillers, polymers and resins other ingredients that are capable of absorbing energy and provide an optimal balance of absorption, reflection, transmission and conduction.

[0027] It has been discovered that when a suitable energy-absorbing ingredient is added to a conventional adhesive, reactivation upon short duration of radiant energy can be achieved. Energy-absorbing ingredients contemplated for use in the practice of the invention are commercially available and include, but are not limited to dyes, pigments and fillers. Examples include carbon black, graphite, Solvent Red (2′,3-dimethyl-4-(2-hydroxy-naphthylazo)azo-benzene), Solvent Green, dyes such as Forest Green and Royal Blue masterbatch dye available from Clariant, cyanine-based dyes, oxides such as such as titanium dioxide, and metals such as antimony, tetrakis)dialkylaminophenyl)aminium dyes, cyanine dyes, squarylium dyes and the like.

[0028] Pigments, such as carbon black and graphite, are particulate in nature and will usually have somewhat of a spherical shape with average particle sizes in the range of about 0.01 to about 7 microns. Pigment particles aggregate, so aggregate size will be larger. The pigment aggregate size in hot melt adhesives will preferably be smaller than about 500 microns. Aggregate sizes of less than about 100 microns are preferred, more preferably smaller than about 50 microns.

[0029] A wide variety of organic NIR triggers are described in the literature and are available for use in the practice of the invention. Such compounds include cyanine, metal complexes, quinone, azo, radical multiphenylmethane, perylene, aromatic annulenes, fluorenylium. Such triggers possess various absorption characteristics. For example, halogen substituted 1,4,5,8-tetraanilioanthraquinones have excellent transmittance in the vicinity of 860 nm and can absorb NIR in other ranges. Another example is squaraine, which is characterized by intense narrow absorption bands at relatively long wavelength. Also specifically designed phthalocyanine compounds have been demonstrated exhibiting high transmittance to visible light and offering high efficient cut of near infrared.

[0030] Preferred energy-absorbing ingredients for use in the practice of the invention are broad band near IR absorbers such as Epolight 1125 (Epolene, Inc), SDA6248 (H. W. Sands Corp.), SDA2072 (H. W. Sands Corp.) and carbon black. Carbon black can be purchased from Cabot under trade name of Monarch, Regal, Black Pearl, and Elftex, or Degussa (FW series), or from Columbian Chemical Company (Raven Series). Carbon black can be manufactured by different methods such as the furnace black method, the gas (channel) black method, and the lamp black method. The key parameters affecting the radian energy absorption of carbon black prepared by these various methods are average primary particle size, surface chemistry and aggregate structure.

[0031] Energy absorbing ingredients for use in the practice of the invention will typically have an absorption in the range of from about 400 nm to about 100,000 nM, more preferably from about 700 nm to about 10,000 nm, even more preferably from about 750 nm to about 5000 nm.

[0032] Suitable energy-absorbing ingredients for use in reactivatable adhesives of the invention may be identified by blending a desired adhesive with a chosen additive of various particle size and various amounts. Any conventional method of blending the energy-absorbing ingredient with the adhesive such as through use of a paddle mixer or high shear mixer such as Ross ME-100LC extruder, as would be apparent to the skilled practitioner, may be used to prepare the adhesive compositions of the invention. The starting adhesive and the adhesive containing the energy-absorbing ingredient then are compared by heating samples of each with a light from a radiant heat source. The samples are tested for reactivation efficiency and bonding performance, as described in detailed in the Examples. Reactivation efficiency is the ability the adhesive to become molten in a short period of time. Suitable additives are those that reactivate quickly and exhibit acceptable bond strength. Preferred are thermoplastic adhesives which, when pre-applied to a substrate, re-activates with a short duration of exposure to radiant energy, preferably less that about 10 seconds, more preferably less than about 5 seconds, and provides acceptable bond force after a short period of compression or cooling, preferably a period of less that about 30 seconds, more preferably less than about 15 seconds.

[0033] Included in the practice of the invention are adhesives comprising absorber coated fillers and encapsulated absorbers. For example, the adhesive may comprise a cureative encapsulated within a shell comprising a NIR absorbing agent. Exposure to NIR energy melts the capsule thereby expelling the curing agent and allowing for cure of the adhesive.

[0034] The term tubular, as in a tubular package or tubular packaging capsule is not limited to a cylindrical shaped package but encompasses rectangular shaped packages as well as triangular, hexagonal, pentagonal, octagonal and the like shaped packaging. Packaging containers can have a rectangular, circular, square or other shaped cross-section.

[0035] Paperboard-based containers are in widespread use for the packaging of consumer goods. A typical rectangular packaging container comprises a pair of vertical side panels and a pair of top and bottom panels contiguous with a respective one of the vertical side panels.

[0036] Adhesive is used in all areas of packaging technology (converting and packaging) for the purpose of sealing paper-based containers, e.g., for connecting or sealing folding tabs such as the side seam and top and bottom end flaps.

[0037] In the paper converting process, laminated paperboard cartons are cut to the desired shape for the carton blank, and the fold or crease lines are formed in the laminated structure by a process much like embossing. Subsequent to the converting process, the only fold or crease lines that are further manipulated are those necessary to form the flat, folded configuration. As will be recognized by those skilled in the art, in this configuration, a first and second panel and a third and fourth panel are folded over their respective shared fold or crease lines so that the side seal for the carton (at the fifth panel or flap) can be made. The side seal is conventionally made by the converter. This flat folded configuration is that configuration in which the cartons are supplied to the packagers. All subsequent folds and seals are carried out as part of the packaging machine operation.

[0038] Conventional packaging machines includes a carton magazine for storing flat, folded carton blanks, a feeder for advancing carton blanks to be filed, a carton erection station, a bottom forming and sealing station, and a filling station at which the cartons are filled with product. Following the filling station the cartons' top panels are folded and subsequently sealed. The filled cartons are then off-loaded from the form, fill and seal packaging machine.

[0039] It is evident that prior art packaging machines require at least one gluing station, and usually two, requiring the packager to deal with adhesive inventory, trouble shooting, maintenance of adhesive application equipment and the like.

[0040] As described in commonly assigned and concurrently filed application Ser. Nos. (ATTY docket Nos. 2088 and 2089), both entitled “Method and means for pre-applying an adhesive to a substrate,” the disclosure of which is incorporated herein in its entirety by reference, the converter, in addition to forming the side seal, applies to at least one predetermined location an amount of adhesive sufficient to seal the container. The adhesive applied to the carton blank comprises an energy-absorbing ingredient. By including an energy-absorbing ingredient, the absorption, reflection and transmission characteristics of the adhesive composition is tailored so as to optimize the composition's re-activation and subsequent bond formation. The adhesive is applied to the substrate and, depending on the type of adhesive applied, allowed to dry or solidify. Such adhesives are capable of reactivating upon short duration of exposure to radiant energy, preferably less that about 10 seconds, more preferably less than about 5 seconds, even more preferably less than about 3 seconds, and provides acceptable bond force after a short period of compression or cooling, preferably a period of less that about 30 seconds, more preferably less than about 15 seconds.

[0041] Thus, the flat folded configuration supplied to the packager has all the adhesive elements required to seal the container and the packager can avoid applying adhesive in the packaging line and avoid the problems associated with such application.

[0042] The present invention provides a packaging machine adapted to activate an adhesive present on a carton blank, i.e., a pre-applied adhesive. The machine comprises at least one station capable of providing a directed source of energy to the adhesive present on the carton blank.

[0043] Radiant energy can be supplied by a number of sources, as will be apparent to the skilled practitioner. Both coherent and non-coherent sources may be used. Examples include lasers, a high pressure xenon arc lamp, a coiled tungsten wire, ceramic radiant heater, tungsten-halogen lamps and ultrasonic waves. In a preferred embodiment, radiant energy within the near infra-red (NIR) region is used. Peak wavelengths of from 400 nm to about 100,000 nm may be used. More typically, wavelengths of from 700 nm to about 10,000 nm, most typically from about 750 nm to about 5000 nm will be used in the practice of the invention. Commercial sources of equipment capably of generating radiant heat required for use in the practice of the invention include Research Inc. (Eden Prairie, Minn.), Chromalox (Ogden, Utah), DRI (Clearwater, Fla.), Advent Electric Inc. (Bridgeport, Pa.), and Glo-Quartz Inc. (Mentor, Ohio).

[0044] In the form, fill and seal packaging machine of the invention, a plurality of carton blanks having positioned thereon an adhesive tailored for purpose of reactivation are stored in a flat form in a magazine. The blanks are dispensed by a feeder to a carton forming station where the cartons are erected, bottom sealed, filled and top sealed. In this process, the cartons can also be sterilized, for example, after bottom sealing. The cartons are conveyed in an indexed manner through the various stations and subsequently discharged from the machine at an off-loading station. Generally, the cartons are conveyed through the machine by a belt or like conveying device. The cartons will typically be supported from their respective bottoms which will normally rest on a low friction, stationary table top-like portion of the machine associated with the conveyor.

[0045] The packaging machine of the invention comprises a magazine for storing stacks of flat folded carton blanks, a carton erection station, a filling station and a top and/or bottom forming and sealing station at which will be located a means for proving radiant energy. It is to be understood that the terms “bottom” and “top” are relative terms and not terms used to designate the top or bottom of the finished packaged article. Located at each of the bottom and top sealing stations is a means for proving radiant energy to the adhesive located on predetermined area of the bottom and top forming flaps. The specific source of energy and distance from the surface to be irradiated will be dictated by the type and amount of adhesive used. In one embodiment, the energy source is NIR radiation. It is to be understood that the selection and duration of the radiant energy used will depend on the energy absorbing material incorporated into the adhesive located on the container being sealed.

[0046] In one embodiment, the packaging machine forms and seals one end of the carton, fills the carton and then forms and seals the other end of the carton. In such an embodiment the top and bottom of the carton will be sealed sequentially and the source of energy used to seal the bottom will be located at a site distal the source of energy used for sealing the top. In another embodiment of the invention, the packaging machine fills the carton prior to sealing either end (i.e., the bottom and top ends) of the carton. In this embodiment, the top and bottom of the carton will be sealed substantially simultaneous to each other, with the energy sources located substantially juxtapose to one another.

[0047] While the adhesive may be applied directly to the carton, the adhesive to be reactivated during the packaging of the carton may be placed on the carton blank via a transfer tape or the like. Among transfer tapes contemplated for use is a tape comprising a backing material having a first and a second opposing surface. On one surface is disposed, for example, a pressure sensitive adhesive and on the second surface is disposed a reactivatable adhesive. Useful backing material substrates include foam, metal, fabric and various polymer films such as polypropylene, polyamide and polyester. The pressure sensitive adhesive being used to apply the reactivatable adhesive to the surface of the carton prior to or during the packaging and sealing thereof.

[0048] In contrast to adhesives applied on the packaging line, it has been discovered that adhesive reactivated in accordance with the invention have improved performance properties. Moreover less adhesive is required to be used when pre-applied than when applied on the line. Carton blanks used in the practice of the invention will typically be coated with from about 0.5 mil to about 15 mil of adhesive. The adhesive present on the carton blank reactivates upon exposure to short durations of radiant energy and provide superior on-line performance and set speed which allows for quicker production speeds.

[0049] The type of adhesive that can be reactivated in accordance with the invention is not particularly limiting or critical to the practice of the invention. Reactivatable adhesives encompassed by the invention include but are not limited to hot melt adhesives, waterborne adhesives, solvent borne adhesives, moisture curable adhesives, ultraviolet curable adhesives, blocked urethane systems, epoxy based adhesives, and adhesives comprising an encapsulated cureative or the like. Thermoplastic and hot melt adhesives are particularly useful when formulated for pre-application and subsequent later reactivation and are particularly useful for case and carton sealing. It will be apparent that a thermoplastic adhesive present on a substrate may be applied to a substrate in the form of a waterborne emulsion or solution.

[0050] Adhesives reactivateably by application of a NIR energy source and adhesives reactivatable by application of ultrasonic waves are particularly preferred for use in the practice of the invention.

[0051] The energy-absorbing ingredient may be added, with stirring, any time during the preparation of the base adhesive, or following preparation of the base adhesive. The amount added will depend on the type adhesive, the energy-absorbing ingredient used, the size of the energy-absorbing ingredient and the dissolution or dispersion properties of the energy-absorbing ingredient. The additive is added in an amount effective to reactivate the adhesive upon exposure to short durations (typically less that 10 seconds) of radiant energy. Typically, the additive will be present in an amount of about 0.001 to about 10 parts per 100 parts of the adhesive composition. Reactivatable adhesives containing an energy-absorbing ingredient are described in copending commonly assigned U.S. application Ser. No. 09/933,279, entitled “Reactivatable adhesives” and in commonly assigned and concurrently filed application Serial No. (ATTY docket No. 2090), entitled “Reactivatable adhesive compositions and use thereof,” the disclosures of which is incorporated herein in their entireties by reference.

[0052] In embodiment where the adhesive is sensitive to ultrasonic waves and the invention involves bringing one substrate in contact with the adhesive present on a second substrate, subjecting the first and/or second substrate to ultrasonic compression for a time sufficient to melt/reactivated the adhesive and allowing the adhesive to solidify whereby the first substrate is bonded to the second substrate. In embodiments were reactivation occurs by exposure to ultrasonic energy, the adhesive present on the first substrate may be reactivated either before or after being contacted with the second substrate to be bonded thereto.

[0053] The re-activation and performance of ultrasonically reactivatable adhesives is achieved by incorporating into an adhesive an energy-absorbing ingredients that are sensitive to ultrasonic energy. Examples include thermoplastics, thermosets, low Tg polymers, composites and blends thereof.

[0054] The reactivation efficiency of an adhesive refers to the ability of the adhesive to reactive, e.g., become molten in a short period of time. Reactivation efficiency will depend on the compression pressure, the power and frequency of the ultrasound, the geometry and contact area of the ultrasonic horn and the exposure time.

[0055] Adhesives reactivatable by the application of ultrasonic waves are described in commonly assigned and concurrently filed application Serial No. (ATTY docket No. 2091), entitled “Reactivation of pre-applied adhesives by ultrasonic waves,” the disclosure of which is incorporated herein in its entirety by reference.

[0056] Preferred formulations for the adhesive layer will comprise styrene-butadiene-styrene copolymers, ethylene vinyl acetate, a wax and a tackifier. Elastomeric adhesives with glass transition temperatures below 20 C, or semicrystalline polymers with a melting temperature of below about 20C are particularly preferred.

[0057] Preferred reactivatable adhesive will reactivate upon exposure to ultrasonic energy having a frequency of from about 15-kilohertz to about 60 kilohertz, more preferably from about 20 kilohertz to about 40 kilohertz. Preferably, the reactivatable adhesives are formulated to reactivate to a temperature of at least about 200° F., more preferably to a temperature of at least about 250° F. upon exposure of less than about 2000 watts/sq inch of ultrasonic energy for a period of less that about 10 seconds, more preferably less than about 5 seconds, even more preferably less than about 3 seconds.

[0058] Ultrasonic generators used in the practice of the invention generally and conventionally comprise a transducer, a booster and horn. A booster is typically used to amplify and boost energy. Ultrasonic horns are known in the art and include rectangular horns and rotary horns of cylindrical shape. Preferred geometry for use in the practice of the invention is to press the ultrasound horn onto substrate layers where the adhesive layer is sandwiched in the middle. Alternatively, the substrate may be pressed into the horn. The ultrasonic energy will typically be used at a frequency of from about 15 kilohertz to about 60 kilohertz, more preferably from about 20 kilohertz to about 40 kilohertz.

[0059] The packaging machine of the invention is not limited to the closure of paperboard containers. The packaging machine may be used to seal containers made of a variety of materials. Substrates to be bonded include virgin and recycled kraft, high and low density kraft, chipboard and various types of treated and coated kraft and chipboard. Composite materials are also used for packaging applications such as for the packaging of alcoholic beverages. These composite materials may include chipboard laminated to an aluminum foil which is further laminated to film materials such as polyethylene, mylar, polypropylene, polyvinylidene chloride, ethylene vinyl acetate and various other types of films. Additionally, these film materials also may be bonded directly to chipboard or kraft. The aforementioned substrates by no means represent an exhaustive list, as a tremendous variety of substrates, especially composite materials, find utility in the packaging industry.

[0060] In addition to the advantantages of using a pre-applied adhesive is case and carton sealing operations, use of a pre-applied adhesive in accordance with the invention for the sealing of paper bag endings, pinch bottom bags and the like in place of conventional heat seal closure has the advantage of expanding the types of graphics used in these applications, as the heated compression conventionally used in the art limits the use thereof.

[0061] By modifying the placement of adhesive on the substrate (e.g., top or bottom end flap, vertical side section), the size or surface area, the shape and/or pattern of the adhesive applied to the substrate, packaging may be designed to control the amount of force required to open a sealed package, i.e., control the ease of opening. Thus packaging can be designed that is child proof or, alternatively, geriatrically friendly (i.e., easy open). The adhesive formulations of the invention may be pre-applied in a continuous or discontinuous, e.g., as evenly spaced beads or dots, manner depending on surface area and coating weight desired. Particular patterns may be used to optimize substrate/adhesive contact. Depending on the adhesive, the bead size, thickness, distance apart and pattern will vary.

[0062] In addition, packaging substrates comprising a preapplied adhesive in accordance with the invention is cost effective and enables the use of many packaging designs that could not heretofore be used with prior art packaging systems. Adhesive may be placed and packages designed to be tamper resistant/tamper evident. Specifically, problems associated with adhesive stringing and adhesive “ooze out” or “squeeze out” upon sealing/compression operations encounter in prior art packages and packaging processes that apply glue on the line are avoided when using reactivatable adhesives. Using the process of the invention, packaging materials such as carton blanks can be manufactured that use less paperboard stock. As such, the reactivatable adhesives of the invention may be precisely preapplied to the area to be sealed. The area of adhesive application can be located closer to the distal portion of an end flap to be sealed. This advantage means substantially savings in the amount of packaging materials needed (i.e., the end flap may be smaller). The areas of adhesive may also be placed closer to the fold line, enabling the use of a lighter weight paperboard substrate stock, which also results in a substantial cost savings.

[0063] Drawing FIGS. 1-4 illustrate several types of packaging encompassed by the invention. FIGS. 1 and 2 illustrate typical form, fill and seal embodiments of the invention. FIG. 1A shows a flat carton blank having reactivatable adhesive applied to the one flap of each set of end flaps. FIG. 1B shows the carton folded. FIG. 2 shows a flat form, fill and seal type carton having reactivatable adhesive applied to various end flap fold lines as well as flap sides. This box is designed to be sift proof and tamper proof. Sift proof boxes have an additional advantage that use of secondary packaging material (e.g., the bag within the cereal carton) can be avoided. FIG. 3 illustrates a typical Bliss box package. It will be appreciated that adhesive may, alternatively be placed on the two end panels. FIG. 4 illustrates a typical wrap around package. Many other packaging designs as will be apparent to one skilled in the art are encompassed by the invention.

[0064] The invention is further illustrated by the following non-limiting examples.

EXAMPLES

Example 1

[0065] Adhesive Sample 1

[0066] An adhesive sample was prepared by blending an EVA, paraffin wax, and hydrocarbon tackifier based hot melt adhesive available from National Starch & Chemical Company (Cool-Lok® 34-2125) with 0.3 wt % of carbon black (Regal 400, Cabot) using a paddle mixer.

[0067] Adhesive Sample 2

[0068] 0.5 wt % of Epolight 1125, an NIR absorbing dye available from Epolight, was dissolved homogeneously into the base hot melt adhesive (Cool-Lok 34-2125) and uniformly blended with the adhesive with a paddle mixer.

[0069] Adhesive Sample 3

[0070] An EVA based waterborne emulsion having the composition comprising 88.0 wt % EVA Emulsion (Dur-o-set E-200, Vinamul), 7.5 wt % Diethylene/Dipropylene Glycol Dibenzoate Plasticizer, 4 wt % water and 0.5 wt % Carbon Black (Plack Pearls 4750, Cabot) was prepared by pre-dispersing the carbon black in the plasticizer using a rotor-stator. The the EVA emulsion and water were added using moderate speed axial paddle stirring.

[0071] Many modifications and variations of this invention can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. The specific embodiments described herein are offered by way of example only, and the invention is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A packaging machine comprising a means for reactivating an adhesive present on a packaging substrate, said means comprising a radiant energy source having a peak wavelenth of from about 400 nm to about 100,000 nm.

2. The machine of claim 1 wherein said means is coherent source of radiation.

3. The machine of claim 1 wherein said means is an non-coherent source of radiation.

4. The machine of claim 3 wherein said means is at least one NIR lamp.

5. The machine of claim 1 wherein said radiant energy source has a peak wavelenth of from about 700 nm to about 10,000 nm.

6. The machine of claim 4 wherein said radiant energy source has a peak wavelenth of from about 750 nm to about 5,000 nm.

6. The machine of claim 1 wherein said reactivatable adhesive reactivates to a temperature of at least about 200° F. upon exposure of less than about 1200 watts/sq inch of near infrared energy for a period of less that about 10 seconds.

7. The converting machine of claim 1 wherein the substrate is a celluosic material, a thermoplastic material, a metallic material or a combination thereof.

8. The converting machine of claim 1 wherein the substrate is a plastic material.

9. A process of packaging an article by forming, filling and sealing a package that has had applied to at least a portion thereof a reactivatable adhesive, said process comprising forming and/or sealing a package by exposing the applied reactivatable adhesive to radiant energy for a time sufficient to reactivate the adhesive, said radiant energy having a peak wavelegth of from about 400 nm to about 100,000 nm.

10. The process of claim 9 wherein the applied adhesive is irradiated with NIR energy for a time sufficient to reactivate the adhesive.

11. The process of claim 9 wherein the package comprises vertical side panels, and at least a top and/or bottom flap.

12. The process of claim 11, wherein said adhesive is applied to at least one of said top or bottom flap.

13. The process of claim 11, wherein said adhesive is applied to a vertical side panel.

14. The process of claim 9 wherein said package is a tubular shaped carton.

15. The process of claim 9 wherein said carton is a tubular shaped case.

16. The process of claim 9 wherein the adhesive is a hot melt adhesive.

17. The process of claim 9 wherein pressure is applied to effect said sealing.

18. The process of claim 9 wherein the applied adhesive is exposed to radiant energy for a period of less that about 10 seconds.

19. A form, fill and seal packaging machine comprising a frame, a plurality of stations carried by the frame, and a feeding means for feeding cartons to be formed, filled and sealed, said stations comprising a carton erection station, a bottom and/or top flap sealing station and a filling station, said top and/or bottom sealing station comprising a source of radiant energy having a peak wavelegth of from about 400 nm to about 100,000 nm.

20. The packaging machine of claim 19 wherein said radiant energy source has a peak wavelength of from about 700 nm to about 10,000 nm.

21. The packaging machine of claim 12 wherein the filling station is located between the bottom flap sealing station and the top flap sealing station.

22. The packaging machine of claim 19 wherein the source of radiant energy is at least one NIR lamp.

23. An article of manufacture having applied on at least one substrate surface thereof an adhesive comprising an energy-absorbing ingredient and which is capable of being reactivated upon exposure to short durations of radiant energy having a peak wavelength of from about 700 nm to about 10,000 nm.

24. The article of claim 23 which is a flat carton blank.

25. The carton blank of claim 24 which is a flat, folded carton blank.

26. The carton blank of claim 24 wherein the adhesive is capable of being reactivated upon exposure to radiant energy for a period of less than about 5 seconds.

27. The carton blank of claim 24 wherein the energy-absorbing ingredient present in the adhesive is a pigment.

28. The carton blank of claim 27 wherein the energy-absorbing ingredient present in the adhesive is carbon black.

29. The carton blank of claim 24 wherein the energy-absorbing ingredient present in the adhesive is an organic dye.

30. The carton blank of claim 24 wherein the adhesive is a thermoplastic adhesive.

31. The carton blank of claim 24 which has easy open and reseal properties.

32. The article of claim 23 which is a tape.