Roasted coffee creates outflow of gas after its roasting. For example, 1 kg of fresh roasted coffee bean could generate about 10 liters of CO2 gas at a decreasing rate from the time of roasting. It can be important to package the coffee in a way that keeps its freshness while compensating for this gas generation.
A packaging film that is a high barrier to oxygen and moisture is typically used in packaging to preserve the coffee from degrading. An airtight flexible package would accumulate CO2 gas and build air pressure until the package ruptures. A common solution in use today is to install a 3 piece molded plastic valve that is welded to the interior of the coffee bag. The film material is mechanically breached within the circular valve weld to allow CO2 to escape though the valve and the breach in the film. The valve prevents air from entering the package but allows the CO2 to vent. A vent that allows CO2 to escape must also address the negative effects of allowing the fresh roasted aroma from escaping as well as allowing oxygen and moisture from entering the package which will degrade the sensory aspects of the coffee as well as shorten the shelf life. Other packaged items other than coffee also have an off gassing effect that would benefit from this type of vent, with or without a sealing film valve.
The present invention creates a package from a packaging film, and uses a laser etching process to create a vent in the package film itself. This eliminates the expensive 3 piece molded valve. As such, this offers a better and more economical solution to eliminate CO2 gas buildup.
A laser etched or scored pattern on packaging film used in coffee bags is disclosed. This pattern can be used with or without an additional sealing film valve. This pattern provides a higher performance and lower cost packaging solution by releasing the buildup pressure caused by the emission of CO2 gas from fresh roasted coffee beans and grounds inside the coffee bag.
In the Drawings:
Embodiments describe a laser etched vent that addresses many of the problems discussed above.
An embodiment is described herein may form the package using the techniques described in our patent application Ser. No. 13/899,387, filed May 21, 2013.
Advantages to the laser etched vent include, but not limited to:
Another advantage of this system is ease of production and process flow.
The laser etched vent with or without the additional sealing film valve can be created and applied onto any roll stock prior to packaging coffee. As described herein, the vent can be formed in a way that allows the vent to be crushed, in order to roll the packaging film onto the roll stock. Then, when the roll is unrolled, the laser etched vent will inflate in size. In contrast, the standard 3 piece valve must be welded onto the packaging film at the time of packaging the coffee. This requirement is because the roll stock of packaging film cannot be rewound after the bulky standard valve has been welded in place on the film.
Better oxygen and moisture barrier. The laser etched vent can be designed to vent exactly to the requirements for any type of coffee bean, ground or whole bean, which currently packaged in coffee bags.
The laser etched vent can be tailored to have the properties of a smaller aperture. This in turn will allow the specific amount of CO2 to escape and will in turn restrict air from outside of the package to enter. This will prevent excessive amounts of oxygen and moister to spoil the coffee. The addition of a sealing film valve further restricts outside air from entering thus extending the shelf life of the coffee within the bag.
Construction and design of laser etched vent utilizes the structure of a flexible packaging film.
A common film construction of flexible packaging for retail coffee is shown in
An exterior printed polyester (PET) layer(s) 100, 102 forms the outer layer of the cross section of the package. The outer layer is underlied by an intermediate barrier layer 110. This intermediate layer 110 is typically formed of a foil metalized layer, e.g., a metalized PET, aluminum foil, or ethylene-vinyl-alcohol (EVOH) material. There can be an optional additional layer 115 of PET or PA (polyamide Nylon) on the interior surface of the barrier layer 110. The interior layer 120, that holds and packages the product is formed of polyethylene (PE) or polypropylene (PP) and often an additional sealing layer 125. Normally this can also be PE or PP.
The embodiments described herein explain formation of a laser etched vent. One embodiment forms the vent by using the selective absorption of different frequencies of laser light in each of multiple layers of a packaging film.
A breach is formed as shown in
The film that is used can commonly range in thickness of 50 to 180 microns (0.002″ to 0.007″), although other thicknesses can be used. In this embodiment, the breach is formed through three layers, including an interior layer 215, an intermediate layer 220, and an outer layer 230. The interior layer 215 can be for example a PE, PE-PET, PP or PP-PET sealing layer. PET represents polyester. The sealing layer is commonly PE or PP with or without a PET or PA. Other materials are possible including co polymers The interior breach 210 is at a first lateral location in the interior layer 215. The interior breach then forms a channel 225 between an inner wall of the interior layer 215 and an outer wall of the intermediate layer 220. The intermediate layer 220 may be formed of different materials, and in this embodiment is formed of a metalized layer, foil, or EVOH. The interior breach 210 is formed at a first lateral location, which leads via the channel 225 to a second lateral location where is located the exterior breach 240. The channel is formed along the surface of the intermediate layer without compromising the exterior or interior layers. The channel also extends into the interior, as shown for example in
The exterior breach is formed in both the intermediate layer 220 and the exterior layer 230, where the exterior layer 230 can be formed, for example, of printed layers of PET.
The breaches are sized sufficiently to expel the CO2 gas evolved from the material inside, preferably coffee, without increasing the interior pressure of the package beyond an acceptable point. The design of the laser etched vent preferably does not exceed the maximum required air flow by more than a safety factor, as a determined percentage over the known rate to reduce the risk of excessive pressure buildup. The restriction to air flow is proportional to a factor of the intermediate breaches' cross sectional area and length. One embodiment may use multiple long narrow channels that would release the same amount of CO2 and have a lower OTR value.
Limiting the airflow though the etched feature to little more than the maximum required amount also limits the amount of oxygen and moisture that is allowed into the package. Oxygen and moisture being allowed into the package tends to degrade the coffee in the package. The gradual generation of CO2 flowing though the etched feature effectively eliminates the counter flow of exterior air and moisture from entering the package when the velocity of CO2 flowing out of the package is greater than the diffusion rate for Oxygen or water vapor. The flow of exterior air and moisture into the package is restricted to conditions where the interior pressure of the package is equal to or less than the exterior air pressure, that is to say after the CO2 gas has evolved from the coffee beans or grounds. The addition of another layer covering the exterior breach, e.g., a sealing film valve further limits the counter flow of air into the package while only restricting the exhaust of CO2 slightly.
According to another embodiment, the channels are sized as to seal or partially seal with the gradual swelling from absorption of oil from the coffee into the PE or PP interior layer. This swelling would decrease the ability to vent CO2 as the amount of CO2 that needed to be vented decreased. This sealing would decrease the ability of oxygen and moisture, however, from entering the package.
The counter flow of oxygen into a package, as measured by Oxygen Transmission Rate (OTR), per laser etched vent feature and without a sealing film valve is around 1.5 to 0.01 ml per day depending on the design of the vent, specifically the length and the cross sectional area of the channel. The design of the vent is dependent on the venting characteristics and amount of the roasted coffee. A wetted layer (sealing film valve 1120 wetted with oil, as described herein) covering the exterior breach reduces this amount to less than 0.01 ml per day. The industry standard molded valve weld is rated at 0.05 ml per day. A small perforation of 65 microns (0.0026″) in diameter directly though the packaging will exhaust CO2 at a rate over 100 times the maximum required rate (deflates 500 ml of CO2 at 1 PSI in 30 minutes) and has a very high OTR of 143 ml per day. While the channels and breeches in the 3 part laser etch vent are in the 50 to 200 micron range, their combined OTR and air release values are equivalent to a hole that is 0.7 microns (0.00003″) in diameter. At a channel cross sectional area and length that would be equivalent to a hole the diameter of 0.7 microns, each laser etched vent would allow an OTR transfer of around 1.5 ml per day and deflate 500 ml CO2 at 1 PSI in around 24 hours. Alone, the laser etched vent would be sufficient to preserve the coffee in the package to a period of time after the all CO2 has been exhausted. The addition of a sealing film vent would extend the preservation time well beyond the CO2 being exhausted and past coffee in a bag using the standard 3 piece molded valve.
Laser converting the packaging material lowers the cost by eliminating the 3 piece molded valve. Laser converting also increases the efficiency of the production process by allowing the conversion to happen offline from the packaging operation. Cumbersome in-line installation of the 3 piece molded valve is required due to the valve's bulk prohibiting rolling the film on a core. Laser etching the vent offline, even with the addition of a sealing film valve, will not prevent the film from being rolled on a core or operations in standard flow wrap/filling equipment.
The following provides a more detailed description of the laser etching film structure.
1. Channel
A variety of lasers can be used to etch the channels that control the flow of CO2 and air. The United States Patent Publication 2015/0102022 A1 illustrates this method. The selective absorption of a focused CO2 laser beam, coherent light at 10.6 micron nominal wavelength, will preferentially absorb into a PET material more than PE and will mostly reflect off a metalized or foil layer, leaving the foil intact.
A preferred method of doing this is by applying a focused CO2 laser beam from the interior 320 of the film to a foil 330 that is in contact with a PET film 325. The resulting channel is created by the vaporizing the PET film. This will also result in lessening of the reduction of flow which could otherwise be caused by physically crushing the channel. The material that was vaporized leaves a void (or channel) that remains even after the film has been crushed, and is then relaxed.
An alternative embodiment removes material through vaporization to form the channel, with or without the resulting bulge.
Another embodiment shown in
A shorter wavelength laser such as a fiber laser, operating around a 1.06 micron wavelength can be used as in
2. Interior Breach
The interior breach size has little effect on the overall flow rate of the three part system formed by the interior breach, channel, and exterior breach. The breach should be small or can in certain embodiments include features, such as a filter or strainer, to prevent coffee grounds or particles from blocking the channel. Such a feature created by the laser in a similar manner as the channels. The feature is an area of delamination of the interior and barrier layers that CO2 gas would have to pass through to enter the channel on the way out of the package. The delamination area or channel grid area would increase overall air flow restriction very little and would create a place for coffee particles to settle or be filtered out before entering the channel and possibly blocking air flow through them.
Exterior Breach
Exterior Seal: Sealing Film Valve
Previous embodiments show how Channels created by the CO2 or fiber lasers create a raised surface or ridge on both the interior and exterior of the film. The ridge can be crushed but returns to near original shape when pressure is released. This is because, in most cases, the film has a good memory for the ridge, caused by, at least in part, metal particles from the vaporized foil embedding into the interior and exterior layers, and binding those layers into their expanded shapes. The film also has a memory for the ridges by being heated during the formation of the bubble and cooling in the inflated state. The film cooling in the inflated shape defines its new natural or relaxed shape. The exception is when a certain kind of short wave laser is used to create the channel. The shortwave laser may harden the aluminum and it therefore does not rebound from being crushed. In this embodiment shown in
This is shown in further detail in
In operation, gas pressure, e.g., CO2, inside the package can cause pressure that will vent through the seal between the bumps 815 and the film layer 820. After the pressure is released, the seal is re-formed. The oil 825 also helps to re-form the seal after it has been broken, for example, by escaping CO2 gas. The surface energy of the oil 825 forms a wetting meniscus between the sealing film 820 and the ridge 815 wherever the two are in contact. The meniscus draws the film to the ridge like a zipper closing.
The seal can also be formed with a low durometer rubber or gel like or a viscoelastic gel like the solidified mineral oil common in gel candles.
The film of the sealing film valve should lay completely flat on the circle to be most effective. If there is a gap between the ridge of the circle and the film, then outside air could get in to the exterior breach. One way in which such a gap could be formed is by a wrinkle in the film. An alternative embodiment is shown in
A cross-section along the line 9B-9B is shown in
The interior package pressure required to break the meniscus seal decreases as the area of the circle the seal is formed on increases. The total force is a factor of pressure applied over an area. The seal on the smallest diameter circle determines the cracking pressure of the valve. In one embodiment, the escaping CO2 is allowed to exit the exterior breach at a point that is lower than the raised surface of the ridges and sealing film. A wet seal encompassing the entire exterior breach would increase the cracking pressure by the inverse of the area of the exterior breach. The exterior breach 900 is located, in part, on a ridge created by a channel, according to an embodiment. An exterior breach that is created by a line that extends from a channel ridge to a non-etched surface as in
Likewise, a pattern of ridges 910 on the inside of the concentric sealing features allows escaping CO2 to distribute and pressurize the entire area inside of the sealing feature and helps to maintain a parallel surface for the sealing film to contact.
The cracking pressure of the valve can be set or designed to a level that would reduce the effect of changes in the barometric pressure which often fluctuates as much as 0.3 PSI per week. If the cracking pressure is set to zero, the package would experience a negative pressure or partial vacuum each time the barometric pressure increases. This negative pressure would increase the likelihood that exterior air and moisture would infiltrate the package. The inventor believes that a cracking pressure of 0.3 PSI may be optimal to nearly eliminate the possibility of a negative pressure in the package due to barometric pressure changes.
The film that forms the seal is formed of a material that does not swell when exposed to the oil that is used on the interface of the seal. The layer of oil should be applied thick enough to form a complete meniscus on at least one of the concentric circles. Any oil in excess of forming a meniscus does not contribute much to the lowering of the OTR value. Excess oil may also increase the chances of oil flowing into the exterior breach. The exterior breach and the channel will increase in air flow resistance with the introduction of oil on their interior surfaces and too much oil may completely block the flow of CO2 escaping.
This can be as further shown in
This stiffening layer 1230 that holds the package film and the sealing film flat to one another.
Another embodiment recognizes that gas generation in modified atmosphere packaging, or “MAP” sometimes builds up air pressure and the result is a package that balloons up. Some packages, however, may preferably be formed of a material 1301 that is not suitable for laser etching of a channel vent as in the previous embodiments. E.g., Some clear PETs or PEs may not be laser etchable. According to an embodiment, shown in
This will allow a MAP package to be made out of clear PET (or other specialty material that cannot be processed by lasers as done herein) to show its contents and not rupture or balloon up.
Other embodiments are contemplated. For example, while the above embodiments have described a specific material, other materials could be included. Certain plastics which are laser transmissive, for example, can be used in place of the PE or PET described herein. Also, while these techniques can be used to protect coffee in a package, they can also be used to protect other materials in such a package.
Those of skill would further appreciate that these features can be carried out using different materials and different techniques different words and different shapes.
Also, the inventor(s) intend that only those claims which use the words “means for” are intended to be interpreted under 35 USC 112, sixth paragraph. Moreover, no limitations from the specification are intended to be read into any claims, unless those limitations are expressly included in the claims.
Where a specific numerical value is mentioned herein, it should be considered that the value may be increased or decreased by 20%, while still staying within the teachings of the present application, unless some different range is specifically mentioned. Where a specified logical sense is used, the opposite logical sense is also intended to be encompassed.
The previous description of the disclosed exemplary embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these exemplary embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
This application claims priority from Provisional application No. 62/331,352, filed May 3, 2016, the entire contents of which are herewith incorporated by reference.
Number | Date | Country | |
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62331352 | May 2016 | US |
Number | Date | Country | |
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Parent | 15229052 | Aug 2016 | US |
Child | 15492507 | US |