Patent Application
20230234739
The present invention relates generally to the field of product packaging, and more particularly to shrink wrapping systems and methods for heat sensitive products that employ localized infrared radiation (IR) outside heat-sensitive areas of the product in association with maximizing IR absorbance by shrink films with defined IR absorbance levels.
A known method of product bundling includes wrapping a group of products (e.g., thermoplastic bottles) with a shrink film and passing the wrapped packages through a hot air oven such that the air temperature exceeds the film activation temperature. This allows the film to stretch tight around the products, creating a robust bundle which keeps the products secured during handling and transportation. A disadvantage of this method is that if the products are heat sensitive (e.g., thermoplastic bottles with thin walls, products that are made from a material with a low melting point, and/or packaging with delicate labels and/or decorative) they can be damaged by the high heat required to shrink the shrink film. Although this problem could be minimized by using a shrink film with a lower activation temperature, attempts to develop such a film have been unsuccessful.
Another known method for shrink bundling products involves application of infrared radiation (IR) to the product with a shrink sleeve loosely placed around the product such that the IR gets absorbed by the film, converted into heat and shrinks the sleeves around the product, creating shrink labels. However, these methods lead to the same drawbacks as the traditional hot air technology when applied to heat-sensitive products because of the high intensity of the IR required to shrink the bundling film.
Finally, a combination of a hot air heating with IR is used for some industrial processes for the purpose of curing and drying where each of these methods alone is not sufficient to deliver the required result for heat-sensitive products. However, these processes are imprecise and can damage heat-sensitive products.
Thus, there is need for improved bundling techniques for heat-sensitive products that create robust bundles with existing shrink films, while also minimizing or eliminating bottle deformation caused by existing shrink-wrapping machines and processes.
The present invention can solve one or more drawbacks noted in the Background section. In one embodiment, a method for shrink wrap bundling a group of heat-sensitive products is provided. The method for bundling a group of products comprises: providing a heating oven with a convective heat source and a radiant electromagnetic energy source therein and a group of heat-sensitive products, wherein the group of heat-sensitive products comprises a front side, a back side, a top, a base, a right side, and a left side, and wherein each heat-sensitive product of the group of heat-sensitive products comprises a wall with a thickness made from a material with a softening temperature; and wrapping the group of heat-sensitive products with a shrink film that comprises an activation temperature and an electromagnetic energy absorbance level and covers the front side, the back side, the top, the right side and the left side, and the base forming a wrapped group of heat-sensitive products, wherein the group of heat-sensitive products are wrapped by the shrink film. The method also comprises placing the wrapped group of heat-sensitive products inside the heating oven for a predetermined duration of residence time; exposing the wrapped group of heat-sensitive products to radiant electromagnetic energy for a predetermined duration of exposure time, wherein the direction of the electromagnetic energy is coincidental or approximately coincidental with a plane of the shrink film; and removing the wrapped group of heat-sensitive products from the heating oven resulting in the wrapped group of heat-sensitive products being robustly bundled according to a defined Bundle Rigidity Test without substantial damage to the heat-sensitive products of the wrapped group of heat-sensitive products.
In another embodiment, a system for shrink wrap bundling a heat-sensitive product is provided. The system comprises a heating oven adapted to receive a product loosely wrapped with a shrink film and shrink wrap the shrink film around the product. The system further comprises one or more heating elements that provide convective heat inside the heating oven and a REE source that provides REE inside the heating oven, wherein the REE source directs the REE to a heat-resistant region of the product as opposed to the heat-sensitive area of the product when the product is located inside the heating oven.
The following detailed description is merely illustrative and is not intended to limit embodiments, application and/or uses of embodiments. Furthermore, there is no intention to be bound by any expressed and/or implied information presented in the preceding Background and/or Summary sections, and/or in this Detailed Description section.
To reduce the amount of polymeric material used in packaging, it can be advantageous to make a plastic package with thinner walls, shoulders and corners, rounded shoulders and corners, and/or a shorter and thinner neck (hereafter “lightweight product” or “lightweight bottle”). The lightweight product can be made without pointed or distinct edges or corners. It can be beneficial to bundle these bottles together with shrink wrap for ease and to prevent damage to the products during shipping and transportation.
It can be difficult to bundle lightweight products with traditional shrink wrap in an oven without damaging the products. Shrink films are typically formed with a polymeric material that has been stretched into an extended or oriented polymer film in which the molecular chains are extended or elongated. The shrink film can be made from a plastic polymer material (e.g., polyolefin, polyvinyl chloride, polyethylene, and/or polypropylene), that can be optically transparent or semi-transparent. Application of energy/heat, such as radiant electromagnetic energy (REE), to the shrink film increases the molecular motion of the polymer chains in the film, causing the elongated polymers to recoil or shrink, back to their preferred random and disordered conformation, resulting in the shrink film tightly conforming around the surfaces of the product about which it is wrapped.
However, it was found that using a CERMEX oven used in the typical way to create a shrink wrap bundle lightweight bottles, damaged these bottles. Many bottles that were tested had dimpling and other distortions at the shoulders and bottom corners of the bottle. This damage is not only unsightly, but also compromises the physical integrity of the bottle.
It was found that the deformations were caused by softening the polyethylene terephthalate (PET) material of the lightweight packages in the areas where the heat concentrated (e.g., the shoulders and bottom corners). First, the inventors tried to prevent the damage by reducing the temperature setting of the oven. However, this reduced the bundle integrity, and it was not possible to find an optimum setting where both the lightweight package shape and bundle integrity were maintained at the same time.
It was found that infrared radiation (IR) provided localized heat from the front, back and sides of the bundle, a proper bundling could be achieved at a lower oven temperature setting. Most of IR was applied outside of the zones where package damage was normally seen. This way, the shrink film was able to get to its operating temperature without overheating the sensitive areas of the package, resulting in a robust bundle and undamaged polymeric packaging.
The disclosed subject matter incorporates IR into the bundling process in a manner that is tailored to minimize or prevent damage to the product while also providing for robust bundling according to the Bundle Rigidity Test (disclosed herein). A shrink tunnel system can be provided that incorporates one or more IR panels within the heating oven and/or outside of the heating oven (e.g., at the tunnel entry and/or exit). The manner in which the IR is applied, including (1) the angle/direction of application, (2) duration of application, and (3) intensity of application, is tailored to minimize or prevent damage to heat-sensitive areas of the product, which can be regions of the product that are prone to deformation from excessive heat (e.g., the shoulders and/or bottom corners of the bottle) or able to generate undesirable side effects (such as water vapor from the side walls of the packaging cartons). In some implementations, the IR panels may be positioned relative to the product and the shrink film such that the IR heat is localized outside of the heat-sensitive areas of the product. Additionally, or alternatively, IR energy can be applied in a direction parallel to the planar surfaces of the film, thereby maximizing the amount of IR energy absorbed by the film relative to the amount absorbed by the product. Further, the film can have a known IR absorbance level that exceeds a predetermined value, so that a significant portion of IR energy was absorbed by the film before it reaches the product. The combination of these elements provides for localizing the heat to keep it away from the heat-sensitive areas of the product and maximizes the absorption of the IR energy by the film, thereby minimizing the leftover energy applied to the product and the potential for the damaging the product.
Other suitable ways of focusing the IR energy toward the heat-resistant region and away from the heat-sensitive area of the product include, but are not limited to: tailoring the IR panel dimensions based on the relative dimensions and positions of the heat-resistant and heat-sensitive areas of the product (e.g., making the height of the panel less than the distance between the sensitive areas at the top and bottom of the bottle), using IR panels with a concave shaped surface, using IR mirrors around the panels to direct the IR energy toward the heat-resistant region and away from the heat-sensitive area, using IR lenses between the panel and the product to direct the IR energy toward the heat-resistant region and away from the heat-sensitive area, and using several smaller panels localized against the heat-resistant areas of the product as opposed to a single larger panel. The amount (e.g., intensity and/or duration) of IR energy applied can also be tailored based on the product type (e.g., a group of plastic bottles, a cardboard box, etc.), the material of the product, the softening temperature of the product, the activation temperature of the shrink film, the contents of the product, the design of the product, the dimensions of the product, and the IR absorbance level of the shrink film.
The IR panels can be incorporated into a shrink tunnel system that also uses convective heat (e.g., hot air) heating elements to facilitate shrinking the film around the product in combination with the IR heat. The amount (e.g., temperature/intensity and/or duration) of convective heat applied can be reduced relative to shrink wrapping systems that do not incorporate IR heat. In this regard, the combination of the IR heat with the reduced convective heat temperature provides for significantly reducing damage and deformation to heat-sensitive areas of a product while further providing for robustly bundling the product according to a defined Bundle Rigidity Test (described herein). The disclosed techniques can thus be used to robustly bundle heat-sensitive products with standard, commercially available low-cost shrink films without substantial damage to the product. An energy source different from IR can be utilized, such as radio frequency (RF), microwaves (MW), visible light or ultraviolet (UV). In this regard, the disclosed systems and methods can incorporate other forms of radiant electromagnetic energy (REE) to facilitate shrink wrapping heat-sensitive products. The term REE as used herein refers to any form or radiant electromagnetic energy, including IR, RF, MW, UV and other forms.
The disclosed techniques can be used for bundling a variety of products. In various exemplary, the disclosed techniques are described in association with bundling groups (e.g., including at least one, alternatively two or more, alternatively three or more, alternatively four or more, alternatively five or more, alternatively six or more, alternatively eight or more) of heat-sensitive products formed with a polymeric (i.e., plastic) material. For example, the products may include bottles for cosmetic and personal care compositions (e.g., soap including liquid hand soap, body wash, hair care products including shampoo, conditioner, and/or styling products, and/or lotion, serum, and other skin care products), laundry detergent, dish soap, mouthwash and other oral care products, household and surface cleaners, insect repellants, water, and the like. However, the disclosed techniques are not limited to bundling polymeric bottles and can be applied to shrink wrap bundle other types of products. The disclosed techniques can also be used for in association with bundling products sold in tubes (e.g., toothpaste, hair care products such as conditioner and styling products, lotion) that include polymeric tubes, metal tubes, and laminates that include a combination of different materials. The disclosed techniques can be used for bundling of the heat-sensitive packaging cartons made from other materials (e.g., pulp, paper, cardboard or other moisture-absorbing materials, aluminum or other metals, and/or bamboo). With these implementations, the use of IR without hot air and/or reduced hot air minimizes the amount of moisture released by the carton during the shrink-wrapping process that can condense on the outside of the product placed into the carton and damage the product. Still, another application of the proposed invention is for the packaging of the articles, in particular articles with polymeric portions, such as toothbrushes, hairbrushes, etc. The disclosed technique can also be used for securing a shrink sleeve label to one or more packages.
One or more embodiments are now described with reference to the drawings, wherein like referenced numerals are used to refer to like elements throughout. Repetitive description of like elements illustrated throughout the figures is omitted for sake of brevity. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a more thorough understanding of the one or more embodiments. It is evident, however, in various cases, that the one or more embodiments can be practiced without these specific details.
During operation, the loosely wrapped product is conveyed inside the heating oven 126 through the infeed opening 110 via the conveyor belt 112 in the machine direction (e.g., along axis Y-Y′). Once inside, the shrink tunnel system 100 can employ REE (e.g., IR or another form) or a combination of REE and convective heat to shrink wrap the shrink film 116 around the product 114, causing the shrink film 116 to shrink and tighten around the product 114, thereby forming a bound or bundled product. The bundled product is then conveyed outside the heating oven 126 through the exit opening 130 and removed. As described in greater detail below, the manner in which the REE is applied to the product 114 and the shrink film 116, including the particular areas of the product 114 to which the REE is localized, the angle/direction of application of the REE to the product 114 and the shrink film 116 and the duration and intensity of application, is tailored to minimize or prevent damage to heat-sensitive areas of the product 114 while also robustly bundling the product 114 according to the Bundle Rigidity Test (described herein). The amount (e.g., intensity and/or duration) of REE applied can also be tailored based on the known REE absorbance level of the shrink film 116, the material of the product, the softening temperature of the product, the activation temperature of the shrink film, the contents of the product, the design of the product, and the dimensions of the product. In some examples, the shrink film can include infrared absorbers. Further, in embodiments in which shrink tunnel system 100 also use both REE and convective heat, the amount (e.g., temperature/intensity and/or duration) of convective heat applied can be tailored to account for the usage of both convective heat and REE heat. In particular, the amount of convective heat applied can be reduced relative to shrink wrapping systems that do not incorporate REE heat, thereby minimizing damage and deformation to heat-sensitive areas of a product while further providing for robustly bundling the product according to the Bundle Rigidity Test (described herein).
To facilitate this end, the heating oven 126 can include a convective heating system that provides a main source of convective heat inside the heating oven 126 and/or an REE source that applies REE within the heating oven 126. The REE source include or correspond to an electromechanical machine or device that generates and emits one or more forms of REE. For example, the REE includes IR and the REE source can include or correspond to one or more IR panels. Additionally, or alternatively, the REE can include (but is not limited to) RF, MW, or visible light or UV light. In
The convective heating system can include one or more heating elements that provide convective heat inside the heating oven 126, one or more fan assemblies that circulate the heated air inside the heating oven 126 and adjustable dampers that direct the heated air to specific areas of the heating oven 126. The heating elements, fan assemblies and dampers are located inside the heating oven 126 and are thus hidden from view in
The shrink tunnel system 100 further includes a control unit 120 that includes hardware and/or software components that provide for controlling one or more of the electromechanical operations of the shrink tunnel system 100. For example, the control unit 120 can include one or more machine controls and machine control devices of the shrink tunnel system 100 (e.g., relays, IR panel controller, heating system controller, temperature controller, conveyor belt controller, motor controllers, main power switch, main disconnect switch, etc.). The control unit 120 can be communicatively and/or operatively coupled to the various electromechanical components of the shrink tunnel system 100, including but not limited to, the heating system, the REE source (e.g., IR panels or the like), the conveyor drive assembly 117, a cooling system (e.g., the fan 134 and other cooling elements), vents, temperature controls, sensors, and the like. The machine interface used for control unit 120 can vary. In the embodiment shown, the control unit 120 includes a display 122 and some electromechanical knobs and buttons that can correspond to one or more machine controls for controlling one or more electromechanical operations of the shrink tunnel system 100. In some implementations, the display 122 can include a touchscreen display that presents graphical controls via a graphical user interface rendered on the display 122. The control unit 120 can include or be operatively coupled to at least one memory that stores computer executable instructions and at least one processor that executes the computer executable instructions stored in the memory, as discussed herein with reference to
The dimensions of the shrink tunnel system 100 can vary. In one embodiment, the dimensions of the entire system are about 200 centimeters (cm) wide, 350 cm long, and 200 cm high, and the dimensions of the heating oven 126 are about 100 cm wide, 250 cm long, and 40 cm high. For example, with reference to
The one or more REE elements 402 can include or correspond to an electromechanical machine or device that generates and emits one or more forms of REE. The REE can include IR and the one or more REE elements 402 can include or correspond to one or more IR panels. Additionally, or alternatively, the one or more REE elements 402 can correspond to electromechanical panels that emit RF, MW, or visible light or UV light. In either of these embodiments, the REE elements 402 (e.g., panels) can be positioned on opposite sides of the conveyor belt 112 with respective emission surfaces 411 facing toward one another such that the emit REE toward one another (e.g., toward the centerline of the conveyor belt 112) in the direction indicated by the dashed arrow lines in
In particular,
As illustrated in
With reference to
When the loosely wrapped product is positioned between the opposing REE elements 402, the elements can apply REE to the shrink film 116 and the product (e.g., product 502, product 114 or the like). The REE applied to the shrink film 116 and product by the REE element gets absorbed by the shrink film 116, converted into heat and increases the temperature of the shrink film 116 around the product, causing the shrink film to shrink wrap around the product. As noted above, the angle or direction of the emitted REE is perpendicular to the machine direction and thus parallel or substantially parallel with the respective surfaces of the shrink film 116 as loosely wrapped around the product. As a result, the absorption of the REE by the film is maximized, thereby minimizing the amount of leftover energy applied to the product (e.g., the product container and its contents) and potential damage to the product caused by the REE. In addition, to the angle of emission, the dimensions (e.g., length and height) and position of the one or more REE elements 402 and can be tailored to prevent or minimize application of the REE to one or more heat-sensitive areas of the product, as discussed in greater detail below.
The duration of application of the REE and the amount of REE (e.g., intensity/temperature) applied can be tailored based on the REE absorbance level of the shrink film 116, the type of REE emitted (e.g., IR, RF, MW, UV, etc.), the activation temperature of the shrink film 116, the product type (e.g., plastic bottle, cardboard box, etc.), the material of the product 114, the softening temperature of the material, the contents of the product 114, the design of the product 114, and/or the dimensions of the product 114. The duration and amount (e.g., intensity/temperature) of REE applied can be controllable via one or more machine controls coupled to the respective REE elements 402 and optionally the control unit 120. In some implementations, one or more temperature sensors (e.g., thermocouples) can be coupled to the REE elements 402 to monitor the surface temperature of the respective elements which can be sent to the control unit for displaying to the operator and/or further processing as described with reference to
The duration and amount of REE applied can also be tailored based on whether convective heat is also applied within the heating oven 126 in addition to the REE and the amount (e.g., temperature and duration) of heat applied. In this regard, the shrink tunnel system 100 can be configured to apply only REE radiant within the heating oven 126 and no heat (e.g., the heat may be turned off and/or the heating system may be excluded from the shrink tunnel system 100). In other embodiments, the shrink tunnel system 100 can be configured to apply both REE and heat (e.g., via the heating system) to the shrink film 116 and product (114 when located inside the heating oven 126 to shrink the film around the product. With these embodiments, the amount (e.g., temperature and/or duration) of hot air heat applied can be reduced relative to shrink wrapping systems that do not incorporate REE application. The combination of the REE heat with the reduced hot air temperature provides for significantly reducing damage and deformation to heat-sensitive areas of a product while further providing for robustly bundling the product according to the Bundle Rigidity Test (described herein).
The optimal amounts of convective heat and REE can be tailored to minimize the amount of convective heat and REE needed to achieve a robustly bundled/shrink wrapped product according to the Bundle Rigidity Test (described herein) without damage or deformation to the product. The optimal amounts (e.g., temperature/intensity and duration) of convective heat and REE can be tailored based the type of product type (e.g., plastic bottle, cardboard box, etc.), the material of the product 114, the softening temperature of the product 114, the activation temperature of the shrink film 116, the contents of the product 114, the design of the product 114, the dimensions of the product 114, the dimension of the group of products, the REE absorbance level of the shrink film 116, and the type of REE applied (e.g., IR, RF, MW, UV, etc.). For example, in some implementations in which both convective heat and IR heat is applied a group of loosely wrapped plastic cosmetic bottles with liquid contents (e.g., soap or another type of liquid or gel), the temperature of the heating system (e.g., the temperature within the heating oven 126) can be about 150° Celsius (C) to about 200° C. (and alternatively about 180° C.), and the temperature of the IR panels can be about 490° C. to about 510° C.
With these embodiments, the shrink tunnel system 100 can be adapted (e.g., configured and/or operatively controlled the control unit 120) to apply the convective heat and the REE at the same time, partially the same time (e.g., partially overlapping periods of time) and/or at separate non-overlapping periods of time. For example, in some implementations, the shrink tunnel system 100 can be configured to apply convective heat to the product and the shrink film 116 the entire duration of time the product is located inside the heating oven 126. In other implementations, the shrink tunnel system 100 can be configured to apply convective heat only a portion of the time. In this regard, the term “residence time” is used herein to refer to the duration of time the wrapped product is located inside the heating oven 126, the term “convective heat exposure time” or “exposure time” is used herein to refer to the duration of time the wrapped product is exposed to convective heat within the heating oven 126, and the term “REE application time” or “application time” is used herein to refer to the duration of time the wrapped product is exposed to REE within or outside the shrink tunnel. The convective heat exposure time and/or the REE application time can be less than or equal to the residence time. The REE application time may also be less than, greater than, or equal to the convective heat exposure time. The ratio of “REE application time” to “convective heat exposure time” can be from about 1:2 to about 1:1, alternatively from 1:1 to about 1:2, and alternatively from about 1:1 to about 1:5. The convective heat exposure time and the REE exposure time may occur at overlapping windows of time, non-overlapping windows of time, or partially overlapping windows of time.
For example, as show in
The distance 407 between the opposing REE elements 402 and the distance 405 between the opposing guiderails 404 can be tailored for different usage contexts. The distance 407 between the opposing REE elements 402 can be tailored to be closer or farther from the sides of the product or group of products (e.g., a group of bottles) to achieve the optimal intensity/temperature exposed to the product or group of products, which can be tailored as function of the type of product type (e.g., plastic bottle, cardboard box, etc.), the material of the product 114, the softening temperature of the product 114, the activation temperature of the shrink film 116, the contents of the product 114, the design of the product 114, the dimensions of the product 114, the dimension of the group of products, the electromagnetic energy absorbance level of the shrink film 116, the type of REE applied (e.g., IR, RF, MW, UV, etc.) and the amount (e.g., duration and temperature) of heat applied. In some implementations, the positions of the REE elements 402 and the opposing guiderails 404 can be adjustable either manually and/or electromechanically controlled to change the distances 405 and/or 407 respectively for different usage contexts.
With reference to
With reference to
Regardless of the shape and dimensions of the product 114 to be bundled (e.g., a group of bottles, a cardboard box, etc.), the product can include a heat-sensitive area and a heat-resistant region, wherein the heat-sensitive area is more susceptible to damage and deformation to applied heat relative to the heat-resistant region. For example, with respect to bottles formed with a polymeric material, when processed using conventional shrink-wrapping ovens without electromagnetic energy heat, the damage deformations typically include dimples and other distortions, usually observed at the upper shoulders and bottom corners of the bottles. The deformations are caused by softening the polymeric material of the bottles in the areas of heat concentration.
The shrink film 116 can have a known REE absorbance level (e.g., IR absorbance level or the like) and a known activation temperature. The REE absorbance level corresponds to the percentage of the total REE energy absorbed by the shrink film which is converted by the shrink film 116 into heat. The activation temperature corresponds to the minimum temperature required to catalyze the shrink film to change its molecular structure from its elongated form to a condensed or recoiled form. The REE absorbance of the shrink film can be greater than or equal to 5%, alternatively greater than or equal to 15%, and alternatively greater than or equal to 30%. The activation temperature of the shrink film 116 can vary. The softening temperature of the heat-sensitive material used to form the product (e.g., each bottle 114′ or the like) can be less than or equal to the activation temperature of the shrink film 116. The activation temperature of the shrink film can be less than or equal to 180° C., alternatively less than or equal to 150° C., and alternatively less than or equal to 140° C. The thickness of the shrink film 116 can vary and be tailored for different usage contexts and product types. The product 114 can comprise a group of heat-sensitive bottles and the thickness of the shrink film 116 can be selected based on wall/material thickness of the respective bottles. For example, the ratio of the wall thickness to the film thickness can less than or equal to 5:1, alternatively less than or equal to 4:1, alternatively less than or equal to 3:1, alternatively less than or equal to 2:1, and alternatively less than or equal to 1:1.
With reference to
The one or more REE elements 402 may also be positioned relative to the product and the shrink film 116 such the angle/direction of the REE applied is parallel to the plane or surface of the film, thereby maximizing the amount of REE absorbed by the film relative to the amount absorbed by the product, as described above. Additionally, or alternatively, the dimensions and position of the REE elements 402 can be tailored based on the relative dimensions and positions of the heat-resistant and heat-sensitive areas of the product such that the REE energy is directed away from the heat-sensitive areas of the product. For example, in one implementation in which the product comprise a group of bottles respectively corresponding to bottle 114′, the height 509 of the REE elements can be less than or equal to the length of the heat-resistant region 609, and the REE elements can be positioned over the conveyor belt 112 such that the height 509 extends in the longitudinal direction between the upper heat-sensitive area and the lower heat-sensitive area 611. Other suitable ways of focusing the REE toward the heat-resistant region and away from the heat-sensitive area of the product include, but are not limited to using REE elements 402 (e.g., IR panels) with a concave shaped surface that faces the product, using mirrors around the REE elements 402 to direct the REE energy toward the heat-resistant region 609 and away from the heat-sensitive areas 607 and 611, using lenses between the REE elements and the product to direct the REE toward the heat-resistant region 609 and away from the heat-sensitive areas 607 and 611, and using several smaller panels localized against the heat-resistant areas of the product as opposed to a single larger panel.
In accordance with method 1600, the optimal amounts of convective heat and REE can be tailored to minimize the amount of convective heat and REE needed to achieve a robustly bundled/shrink wrapped group of bottles according to the Bundle Rigidity Test (described below) without damage or deformation to the product. The optimal amounts (e.g., temperature/intensity and duration) of convective heat and REE can be tailored based the type of product type (e.g., plastic bottle, cardboard box, etc.), the material of the product 114, the softening temperature of the product 114, the activation temperature of the shrink film 116, the contents of the product 114, the design of the product 114, the dimensions of the product 114, the dimension of the group of products, the REE absorbance level of the shrink film 116, and the type of REE applied (e.g., IR, RF, MW, UV, etc.).
The following tests were performed in association with bundling groups of six lightweight, heat sensitive PET bottles and a standard low cost shrink film with an integrated absorbance level of 11.43% with the peak wavelength of 3.8 microns. The following bottles were tested:
The test was performed at the conditions outlined in the tables below with a CERMEX oven with two IR heaters installed to the inside of the oven. The heaters were installed at the infeed of the tunnel and at 1 inch height from the stainless-steel carrier belt. The CERMEX was run at 30 ft/min (9.14 m/min). The distribution of the hot air in the oven was controlled by the adjustable duct plates called dampers. The dampers were able to change the volume ratio of the air supplied to the bundle's sides and bottom. The position of the damper is described by the A %/B % ratio, where A % is the percent of air directed to the sides, and B % is the percent of air directed to the bottom. A %+B % equals 100%.
The bundle quality was considered strong if it satisfied the Bundle Rigidity Test, described hereafter.
The bottom quality was strong if the film was flat and overlapping portions of the film were secure and bonded together. The bottle quality was not strong if the film formed waves, flaps, was crumpled or otherwise sticks out from the plane of the flat bottom.
Damage was determined by visual detection. If by visual detection the bottle did not have any noticeable damage including, but not limited to, dimpling and/or other forms of deterioration, then it was determined that the bottle was not damaged. On the other hand, if by visual detection the bottle appeared to have visible damage, it was damaged. As used herein, “visual detection” means that a human viewer can visually discern the quality of the bottle with the unaided eye (excepting standard corrective lenses adapted to compensate for near-sightedness, farsightedness, or stigmatism, or other corrected vision) in lighting at least equal to the illumination of a standard 100-watt incandescent white light bulb at a distance of 30 cm.
To be acceptable, the system needed to provide strong bundles and strong bottoms without damaging the bundles for both Type 1 and Type 2 bottles. It is important that the conditions work for more than one shape and/or size to limit changeover time when switching bottle shapes and/or sizes on the packaging line.
Test #1
The first test was to determine whether there was an oven temperature that could create a strong bundle without damaging the bottle. We increased the oven temperature setting in 10° F. increments from 300 to 340° F., changed the settings of the side/bottom dampers and used IR, but were unable to find a proper baseline setting. As we found later, the cause of this was the robust HE bottles which remained intact throughout our test on that day.
As shown in Table 1, the oven temperatures all prevented the bottles from being damaged. However, many of the bundles were weak and all the bottoms were weak. Therefore, an oven temperature of 300-340° F. (148.9-171.1° C.) was not sufficient.
Test #2
For the second test, the oven temperature was constant (set at 350° F.), which was higher than Test #1. The settings for both the side/bottom and total flow dampers were changed.
As shown in Table 2, the Type 2 bottle was not damaged at 350° F. (182.2° C.) and thus appeared robust. Some of the conditions tested were also able to create strong bundles and strong bottles and would be acceptable for shipping and transporting bundles of bottles. Other bottle shapes needed to be tested to determine what conditions could work over more than one bottle shape.
Test 3
Additional testing was performed to determine which conditions would work for Type 1 and Type 2 bottles.
As shown in Table 3, Bottle Type 1 was less robust and more easily damaged than Bottle Type 2. For example, at 360° F. (182.2° C.) there is no damage to Bottle Type 2, however, at this same temperature Bottle Type 1 was damaged. More testing was needed to determine the conditions for the Type 1 bottle.
Test 4
As shown in Table 4, it was found that setting the oven to 360° F. (182° C.) was too high and caused deformation with the Type 1 bottle. When the temperature was dropped to 350° F. (176.7° C.), the damage disappeared but the bundle became weak. Then the oven temperature was increased to 355° F. (179.4° C.) and the bundle was weak, but still without the bottle damage. Thus, we determined that 355° F. (179.4° C.) is the highest temperature for maintaining bottle integrity.
When the IR was added, it was found that the side/bottom dampers need to be set at 0/100 (i.e., 100% of the air is applied to the bottom) setting to maximize the quality of the bundle bottom. It was found that these process settings produced 10 good quality bundles without making process adjustments.
Bundle Rigidity Test
Bundle rigidity is tested by displacing a half of the bundle called “displaced half” relative to the other (static) half of the bundle, by a certain distance at a certain displacement rate and measuring the force required to achieve this. A suitable bundle for the test contains six bottles in a 3×2 configuration. Each half comprises three bottles. To pass the test, the force required to move the displaced half by a predetermined distance must be higher than a specified threshold. The test apparatus consists of the stationary platform, a top clamp, and a pusher. The bundle is tested in its vertical orientation. The static half of the bundle is clamped between the platform and the top clamp. The bottom of the displaced half is not supported. A pusher comes on top of the displaced half in a vertical motion and keeps moving downwards until the desired displacement is achieved, at which point the pusher stops and retreats. The data acquisition system records the pushing force and the displacement of the pusher. As used herein, a bundle of a group of heat-sensitive products is “robustly bundled” if the bundle requires more than 150 N force to move the displaced the half of the bundle by 10.0 mm at a rate of 150 mm/min
Combinations:
A. A method for bundling a group of heat-sensitive products, comprising:
providing a heating oven with a convective heat source and a radiant electromagnetic energy source therein and a group of heat-sensitive products, wherein the group of heat-sensitive products comprises a front side, a back side, a top, a base, a right side, and a left side, and wherein each heat-sensitive product of the group of heat-sensitive products comprises a wall with a thickness made from a material with a softening temperature;
wrapping the group of heat-sensitive products with a shrink film that comprises an activation temperature and an electromagnetic energy absorbance level and covers the front side, the back side, the top, the right side and the left side, and the base forming a wrapped group of heat-sensitive products, wherein the group of heat-sensitive products are wrapped by the shrink film;
placing the wrapped group of heat-sensitive products inside the heating oven for a predetermined duration of residence time;
exposing the wrapped group of heat-sensitive products to radiant electromagnetic energy for a predetermined duration of exposure time, wherein the direction of the electromagnetic energy is coincidental or approximately coincidental with a plane of the shrink film; and
removing the wrapped group of heat-sensitive products from the heating oven resulting in the wrapped group of heat-sensitive products being robustly bundled according to a defined Bundle Rigidity Test without substantial damage to the heat-sensitive products of the wrapped group of heat-sensitive products.
B. The method according to Paragraph A, wherein the softening temperature of the material is less than or equal to the activation temperature of the shrink film.
C. The method according to any of Paragraphs A-B, wherein the electromagnetic energy is localized to an area outside of heat-sensitive areas of the group of heat-sensitive products, wherein the heat-sensitive areas comprise first areas of the heat-sensitive products that are more easily distorted or otherwise damaged or generate more undesirable effects than the rest of the product.
D. The method according to Paragraph C, wherein the localization of the area outside of the heat-sensitive areas comprises tailoring dimensions and a position of the radiant electromagnetic energy source based on relative dimensions and positions of a heat-sensitive area and a heat-resistant region resistant of the group of heat-resistant products as placed within the heating oven.
E. The method according to any of Paragraphs A-D, wherein the shrink film further comprises a thickness and a ratio of the thickness of the wall to a thickness of the shrink film is equal to or less than at least one of 5:1, 4:1, 2:1 or 1:1.
F. The method according to any of Paragraphs A-D, wherein the shrink film further comprises a thickness and a ratio of the thickness of the wall to a thickness of the shrink film is equal to or less than 3:1.
G. The method according to any of Paragraphs A-F, wherein the heat-sensitive products comprise a polymeric material selected from polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polystyrene, and combinations thereof.
H. The method according to Paragraph G, wherein the polymeric material comprises polyethylene terephthalate.
I. The method according to any of Paragraphs A-H, wherein the predetermined duration of exposure time is less than or equal to the residence time.
J. The method according to any of Paragraphs A-I, wherein a ratio of the exposure time to the residence time is from about 1:20 to about 1:1, preferably from 1:10 to about 1:2, and most preferably from about 1:10 to about 1:5.
K. The method according to any of Paragraphs A-J, wherein the electromagnetic energy absorbance level of the shrink film is greater than or equal to 5%, preferably greater than or equal to 15%, or more preferably greater than or equal to 30%.
L. The method according to any of Paragraphs A-K, wherein the activation temperature of the shrink film is reached with a lower convective heat temperature relative to the heating oven without the radiant electromagnetic energy source.
M. A system, comprising:
a heating oven adapted to:
one or more heating elements coupled to the heating and that provide the convective heat inside the heating oven; and
a radiant electromagnetic energy source that emits the radiant electromagnetic energy inside the heating oven, wherein dimensions of the radiant electromagnetic energy source and a position of the radiant electromagnetic energy source within the heating oven result in localizing the radiant electromagnetic energy to a heat-resistant region of the heat-sensitive products as opposed to localizing the radiant electromagnetic energy to the heat-sensitive area of the heat-sensitive products when the heat-sensitive product is located inside the heating oven.
N. The system according to Paragraph M, wherein the radiant electromagnetic energy source emits the electromagnetic energy in a direction parallel to respective surfaces of the shrink film as loosely wrapped around the group of heat-sensitive products when the group of heat-sensitive products is located inside the heating oven.
O. The system according to any of Paragraphs M-N, wherein the heating oven comprises a ceiling, a base opposite the ceiling, opposing sidewalls, an infeed opening and an exit opening, and wherein the system further comprises:
a conveyor belt adjacent to the base that feeds the product into the heating oven in a machine direction through the infeed opening and out of the heating oven through the exit opening, wherein the radiant electromagnetic energy source comprises opposing infrared radiation panels located over the conveyor belt and separated by a defined distance; and
opposing guide rails positioned over the conveyor belt between the opposing infrared radiation panels along the machine direction that prevent the shrink film from contacting the opposing infrared radiation panels.
P. The system according to any of Paragraphs M-O, wherein each heat-sensitive product of the group of heat-sensitive products is defined by a base region, a head region and a body extending in the longitudinal direction between the base region and the head region, wherein the radiant electromagnetic energy source further comprises a lower infrared radiation panel positioned under the conveyor belt that heats the conveyor belt and indirectly heats a base surface of the shrink film located adjacent to the base region.
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm” While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
