Package making – Methods – Enclosing contents within progressively formed web means
Reexamination Certificate
2001-06-19
2003-06-10
Patterson, Marie D (Department: 3721)
Package making
Methods
Enclosing contents within progressively formed web means
C053S459000, C053S479000, C053S550000, C053S374400, C053SDIG002
Reexamination Certificate
active
06574944
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to a method and system for ultrasonic sealing of food product packaging. In particular, the present invention relates to a method and system for directly forming and ultrasonically sealing food product packaging around a food product.
Food products are typically packaged in packaging materials for distribution to consumer markets. The food product packaging materials typically may include plastic films, foil wrapping, or paper-based packaging materials. In practice, food products are introduced into the packaging material and the packaging material is then sealed to include the food product. Conventionally, many methods may be employed to seal the packaging material.
Traditionally, food product packaging materials may be sealed using either cold glue-based sealing methods or thermal-based sealing methods. Cold glue sealing typically involves the activation, for example by pressure, of a cold-glue adhesive that has been pre-applied to the edges of the packaging material. In practice, the packaging material may be formed into a desired shape to include the food product. In order to seal the packaging material, the packaging material is typically passed through a sealing apparatus. The sealing apparatus typically applies pressure to the edges of the packaging material to which the cold glue has been pre-applied. The pressure applied by the sealing apparatus activates the cold glue on the edges of the packaging material, causing the edges of the packaging material containing the cold glue to adhere and seal the food product packaging. Cold glue based sealing typically produces seals of sufficient strength for food product packaging applications. A seal of sufficient strength for food product applications is typically strong enough to hold the edges of the packaging material together during transport and handling, but able to be cleanly pulled apart by humans opening the package.
Unfortunately, the traditional cold glue based sealing method includes some significant drawbacks, including discontinuity and interruptions in packaging. For example, a significant problem encountered in cold glue based sealing is the formation of defective seals. For example, a defective seal may occur when an inadequate amount of cold glue is pre-applied to the packaging material. When an inadequate amount of cold glue is pre-applied to the packaging material the edges of the packaging material may not completely adhere together. If the edges of the packaging material do not completely adhere together, air may enter the package and have adverse effects on the food product. Another problem that may occur with cold glue based sealing is when the pressure applied to the edges of the packaging material including the cold glue is not sufficient to activate the cold glue. When the cold glue is not sufficiently or completely activated, the edges of the packaging material may peel away from each other, thus compromising the integrity of the seal. Proper seal integrity is when there are no channels in the seal between the outside of the packaging and the inside of the packaging. When the integrity of the seal is compromised, air enters the packaging and may negatively impact the food product quality. Typically, costly protective barriers are inserted into the laminated field. The barriers, or seals, are used to protect the integrity of the product enclosed within the sealed package. However, the barriers may be wasted if channeling occurs.
A further drawback typical in cold glue based sealing is that extremely precise alignment of the edges of the packaging material is typically required to form a proper seal. If the edges of the packaging material are not precisely aligned when they pass through the sealing apparatus, air pockets or wrinkles in the packaging may form “channels” in the seal. Channels are gaps in the seal through which air can enter the packaging material. As mentioned above, the introduction of air into the packaging may negatively impact the quality of the food product.
An additional drawback to cold glue based sealing is that the cold glue may be sensitive to atmospheric changes in the processing plant. For example, if the temperature or humidity in the plant reaches a critical level, the cold glue may become partially activated, causing the cold glue to adhere to an undesired surface, such as a roll or sheet feeding the packaging material. When the cold glue is prematurely activated and adheres to an undesired surface, the overall speed of the packaging process may be adversely affected, for example, by shutdown of the packaging process.
A further drawback of cold glue sealing is that cold glue sealing requires that the packaging material be sealed with a fairly wide seal. For example, a cold glue seal may require a seal of 10-15 millimeters in order to maintain the necessary integrity of the seal. Because a cold glue seal requires a relatively large seal, the seal requires a significant proportion of the total packaging material required to package the food product. Additionally, components of the system may become jammed during the packaging process. Thus, downtime in the system may occur due interruptions in the system.
The second traditional method of sealing food product packaging materials is thermal-based sealing. Typically, in thermal sealing, no adhesive is applied to the packaging material. Instead, the packaging material is sealed by passing the packaging material between a heated pair of jaws. The pair of jaws are typically heated using thermal conduction, for example, an electric current may be passed through a heating element mounted on the pair of jaws to heat the jaws. As the edges of the packaging material pass between the heated pair of jaws, the edges partially melt and adhere to each other.
Thermal sealing also suffers from a number of drawbacks. For example, thermal sealing is typically a relatively slow process compared to glue-based sealing. Thermal sealing is slow because the edges of the packaging material must be heated enough to melt to form a seal, requiring a relatively longer time. Thermal sealing may, however, provide some advantages to glue-based sealing. For example, a thermal seal may provide for greater seal integrity than provided using glue-based sealing. However, thermal sealing is typically at least an order of magnitude slower than glue-based sealing. Further, the glue seals typically are sensitive to the presence of food material in the seal area. The presence of food material within the seal area typically disrupts the seal. Thus, conventional packaging material sealing applications are often forced to choose between integrity of the seal and speed of formation of the seal.
Ultrasonic sealing may be employed to overcome some of the drawbacks inherent in cold glue-based sealing or thermal-based sealing. Typically, in ultrasonic sealing, ultrasonic energy, instead of conductive heat or an adhesive, is applied to the packaging materials to be sealed. The injection of ultrasonic energy into the packaging material typically heats the packaging material, causing the packaging material to partially melt and adhere to form a seal.
Historically, ultrasonic welding was developed as an alternative to welding technologies such as glue-based or thermal-based. Generally, ultrasonic welding has been employed in various applications for some time. The use of ultrasonic welding is a well established tool for sealing applications such as thermoplastics, textiles, and more recently, food product packaging sealing.
Typically, in processes for ultrasonic sealing of packaging materials, ultrasonic energy is applied to the packaging materials by passing the packaging materials between an ultrasonically activated horn and a stationary or rotary anvil. A typical ultrasonic horn is made of a metallic material having good acoustic qualities, such as aluminum or titanium. A typical anvil is also made of metallic material such as steel or aluminum and is positioned in opposition to the ultrasonic horn. Ultrasoni
Mars Incorporated
McAndrews Held & Malloy Ltd.
Patterson Marie D
LandOfFree
Method and system for ultrasonic sealing of food product... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for ultrasonic sealing of food product..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for ultrasonic sealing of food product... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3143442