Patent Publication Number: US-2009218356-A1

Title: Container for food with modified lid

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Ser. No. 61/031,963 filed on Feb. 27, 2008. The disclosure in the application listed above is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention generally relates to containers for storing and transporting food. 
     BACKGROUND OF THE INVENTION 
     Various containers are used to store and transport food, particularly in the “take-out” food industry. Food storage containers are typically formed by mating a lid with a base. Preferred materials include plastics. Many different containers have been designed to prevent leakage of fluids during travel and prevent or reduce spoilage of foods. 
     When hot food is placed in a container, steam rises from the food increasing the pressure within the container. The lid on the container often rises and bubbles outward from the container, deforming the container. If multiple containers are stacked on top of each other, this deformation will destabilize the stack of containers, increasing the likelihood that the containers will tip and food will leak out of the container. 
     Some of the available lids are designed to allow the steam to escape from the container, and thereby prevent deformation of the lid. However the vent on these lids is typically formed by applying pressure to a perforated area on the lid. Thus these containers are not air tight due to the presence of a perforated area on the lid. These containers are also prone to spilling liquids out of the container. 
     Containers used in the take-out food industry are generally generic containers, void of any identifiers as to the source of the food. Customized containers are expensive to produce. However, restaurants would use customized containers, such as containers with a corporate logo or other descriptive element, if the containers were affordable. 
     There is a need for improved containers for food storage. 
     There is also a need for customized, yet affordable containers for food storage. 
     Therefore it is an object of the invention to provide an improved food storage container. 
     It is a further object of the invention to provide a container that can be customized in a cost effective manner. 
     BRIEF SUMMARY OF THE INVENTION 
     Containers for storing and transporting food, which include one or more vents, an identifier and/or other descriptive element, or a combination thereof on the top of the lid, and methods for making and using the containers are described herein. The base and the lid are formed by injection molding. The vent can be in any suitable shape and contains at least two sections separated by at least one divider. In the preferred embodiment, the vent is circular and contains three sections, each of which is separated from the other sections by a divider. The lids are formed by removing a center portion from the mold cavity to form a facial pocket in the cavity. Then an insert-component with the desired identifier or descriptive element and/or one or more holes for the placement of pins on the outer face of the insert-component is selected and inserted into the facial pocket in the mold cavity. If the insert-component contains one or more holes for the insertion of one or more pins, then the same number of pins, which have the desired vent design on the face of the pin, as the number of holes is selected and one pin is placed into each hole of the insert-component. Then the insert component and/or pin(s) are locked in place with a suitable locking system and a standard injection molding process is used to form the lid. Containers with lids containing one or more vents are particularly useful for transporting and storing hot food. The vent is opened when a user applies downward pressure on the vent, typically using his/her finger. This allows steam to escape from the lid. As the steam escapes, the pressure inside the container equilibrates with the ambient pressure, thereby preventing deformation of the lid and/or enabling the lid to return to its original shape. In a preferred embodiment, the dividers self- seal, when the pressure inside the container equilibrates with the ambient pressure (e.g. returns to Standard Pressure). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a perspective view of a container, where the lid contains an identifier and descriptive element in the central, flat portion of the top. 
         FIG. 2  is a plane view of the top of a lid, where the lid contains a vent in one corner of the central, flat portion of the top. 
         FIG. 3  is an enlarged view of a vent. 
         FIG. 4  is a cross-sectional view of a pin used to form the vent. 
         FIGS. 5A and 5B  are perspective views of the insert-component being inserted into the facial pocket in the mold cavity plate in the midst of the insertion process ( FIG. 5A ) and in the fully inserted position ( FIG. 5B ). 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     I. Containers 
     The containers  100  are formed by mating a lid  200  with a base  300 . The containers are preferably resealable, allowing them to be reused. The lid and base are plastic. Preferably the lid  200  and base  300  are formed from dishwasher-safe and microwave-safe materials. Suitable materials include polyethylene (including high density and low density polyethylene), polypropylene, polyvinylchloride, polyethylene terephthalate, polyhydroxyalkanoates, poly(lactic acid), poly(glycolic acid), poly(lactic-co-glycolic acid), and combinations thereof. In the preferred embodiment, the containers are formed of polypropylene. The lid  200  and base  300  are formed by injection molding processes. 
     a. Lid 
     Any lid formed by injection molding may be modified as described herein to contain an identifier and/or descriptive element, and/or one or more vents on the top of the lid. 
     The lid  200  may have any suitable geometry, such as square, rectangle, polygon, circle, or oblong-shape or oval. Preferably the lid  200  is in the shape of a circle, rectangle or oblong-shape or oval. The shapes of the base and the lid are selected to mate with each other and form an air tight, leak-resistant seal upon mating. 
     Preferably the lid  200  is stackable with respect to another lid  200  of the same shape, so that a plurality of lids  200  having the same size and shape can be stacked with one lid placed on top of another lid. This design minimizes the space required to store multiple lids. 
     b. Base 
     Any base formed by injection molding may be used to form the container, as long as the base mates with the lid. The base  300  may have any suitable geometry, such as square, rectangle, polygon, circle, or oblong-shape or oval. Preferably the base  300  is in the shape of a circle, rectangle or oblong-shape or oval. The shapes and sizes of the base and the lid are selected to mate with each other and form an air tight, leak-resistant seal upon mating. 
     Preferably the base  300  is stackable with respect to another base  300  of the same shape, so that multiple bases  300  can be easily stacked with base upon base. This design minimizes the required storage area for multiple bases. 
     Optionally, the base may have one or more partitions located inside the base to separate the inside of the base into more than one compartment. Optionally, the lid contains one or more partitions that are mateable with the one or more partitions inside the base. 
     Optionally, the base is modified as described herein with respect to the lid to contain an identifier and/or other descriptive element on the bottom of the base. 
     c. Vent 
     Any lid  200  formed via injection molding may be modified to include one or more vents  500  on the top  210  of the lid. The vent contains at least two sections  510 , preferably the vent contains three sections  510   a, b  and  c  (see e.g.  FIG. 3 ). Optionally the vent contains more than three sections. The sections are thinner than the thickness from the top of the lid, In a preferred embodiment, the thickness for the sections is about 15% of the thickness of the top of the lid, more preferably the thickness for the sections is about 14% of the thickness of the top of the lid. For example, if the top of the lid is about 0.02 inches thick, in a preferred embodiment, each section of the vent is about 0.003 inches thick. 
     Each section is separated from one or more sections by divider  520  having a thickness that is less than the thickness of a section. The dividers can be opened by applying pressure, such as via manual application of pressure, to the vent. The dividers  520  are typically slightly raised relative to the height of the sections  510  of the vent on the top of the lid. 
     The vent can be in any suitable shape, including but not limited to square, rectangle, polygon, circle, or oval. In the preferred embodiment, the vent is circular. 
     The preferred embodiment of the vent is illustrated in  FIG. 3 . In the preferred embodiment, the vent is circular and has three identically shaped sections  510   a, b  and  c,  each of which is separated from the other two by a divider  520   a  or  b  that is thinner compared to the thickness of the plastic that forms the sections  510 . Each divider is 120° away from the other dividers, rotating about a point in the center of the circle. In a preferred embodiment, the diameter of the circular vent ranges from 0.2 to 0.5 inches, preferably from 0.3 to 0.4 inches, and most preferably is about 0.3 inches. Preferably the dividers angle upward from each section at a 45° angle, and form a tip  530  at the highest point of the divider. Preferably the tips  530  have widths ranging from 0.004 to 0.006 inches, preferably from 0.005 to 0.006 inches, and most preferably about 0.005 inches. Preferably the dividers  520  have an overall width ranging from 0.01 to 0.03 inches, and more preferably the overall width is about 0.02 inches. 
     In a preferred embodiment, the width and thickness of the dividers are selected to allow the dividers to self-seal after they are opened and the pressure inside of the container equilibrates with the ambient pressure. 
     d. Identifier and/or Descriptive Element on the Top of the Lid 
     The identifier and/or descriptive element on the top  210  of the lid may be used to indicate the source of the food, a tradename or trademark, such as a company or restaurant name and/or logo. Alternative or additional identifiers and/or descriptive elements may be used in place of a corporate logo, including but not limited to identifiers as to the type of food inside the container, warning labels (e.g. “hot food”), etc. 
     II. Method of Making the Containers 
     The containers described herein are manufactured using conventional injection molding processes. In the preferred embodiment, the process is a high speed injection molding process. 
     Plastics are frequently molded into containers with desired shapes through the use of injection molding equipment having an injection unit and a clamping unit. In a conventional injection molding process, after the cavity mold plate (the “cavity”) and core mold plates (the “core”) are each attached to a base. The cavity and core are movable relative to each other between open and closed positions and have opposing faces that meet and define the molding chamber between them, when the cavity and core are in the closed position. The molding chamber defines the shape of a molded article. Typically, one half of the mold is affixed to a stationary platen (often referred to as the “A side” of the mold) while the other half (often referred to as the “B side” of the mold) is affixed to a movable platen. 
     Often, interchangeable mold inserts are used in injection molds for container lids. An example of such an insert is a closure insert or an engraving insert for container lids. Closure inserts mold opening configurations, such as crimp-on, threaded and push in styles into the lid, and thereby allow various closure styles to be utilized with a lid. Engraving inserts allow a custom engraving to be placed on the lid. 
     In some methods, such inserts are secured to the cavity from the face of the cavity by means of a mounting screw. In a preferred method, the inserts are secured to the cavity from the rear of the cavity, most preferably using an insertion and locking system that allows for insertion and removal of the inserts without removing the core and/or cavity mold plates. In a particularly preferred method, at least one of the faces of the core or the cavity contains a facial pocket, the facial pocket is connected to a passageway that extends through the plate and into the base, and the insert is attached to an insert rod, which is inserted into the passageway, thereby inserting the insert into the facial pocket. Then the insert and insert rod are locked in place with a suitable locking system. 
     A pellet or powder resin is melted within a heating chamber of the injection unit. The injection unit includes a piston or ram that pushes the melted plastic past a spreader, often referred to as a “torpedo”, that spreads the melted plastic. This enables improved thermal contact with the heating chamber and thus improves the flow of the melted plastic. The melted plastic then converges at a nozzle which is connected to a sprue located within the mold. The sprue is connected to a gate by a runner that is formed in the mold through which the melted plastic flows. The gate directs the flow of melted plastic into a mold cavity and thereby forms the desired part. Additionally, the gate limits backflow of the melted plastic. Further, the clamping unit provides a clamping force to keep the mold together during the injection molding process. 
     a. Making a Lid that Contains an Identifier or other Descriptive Element on the Top of the Lid 
     To form a lid containing an identifier and/or other descriptive element on the top of the lid, the mold is assembled by removing a center portion (not shown in figures) from the mold cavity  600  to form a facial pocket  610  in the mold cavity. Then an insert-component  620  with the desired identifier or descriptive element on the outer face  622  of the insert-component is selected and inserted into the facial pocket  610  in the mold cavity  600  (see  FIGS. 5A  and B). Finally the insert-component is locked into place using a suitable locking system. 
     After the mold is assembled, a standard injection molding process is used to form the lid. 
     b. Making a Lid that Contains One or More Vents on the Top of the Lid 
     To form a lid containing one or more vents on the top of the lid, the mold is assembled by removing a center portion (not shown in figures) from the mold cavity plate  600  to form a facial pocket  610  in the cavity. Then an insert-component  620  containing one or more holes  624  in the desired locations, which correspond with the locations of the one or more vents, is selected and inserted into the facial pocket  610  in the mold cavity  600 . A pin insert  700  with the desired vent shape on the face  710  of the pin insert  700  (see  FIG. 4 ) is inserted into each hole  624  of the insert-component. Finally the insert-component  624  and pin(s)  700  are locked into place using a suitable locking system. 
     After the mold is assembled, a standard injection molding process is used to form the lid. 
     c. Making a Lid that Contains Both an Identifier or Other Descriptive Element and One or More Vents on the Top of the Lid 
     To form a lid containing both an identifier and/or other descriptive element and one or more vents on the top of the lid, the mold is assembled by removing a center portion (not shown in figures) from the mold cavity  600  to form a facial pocket  610 . Then an insert-component  620  with the desired identifier or descriptive element on the outer face  622  of the insert-component and one or more holes  624  in the desired locations, which correspond with the locations of the one or more vents, is selected and inserted into the facial pocket  610  in the mold cavity plate  600 . A pin insert  700  with the desired vent shape on the face  710  of the pin insert  700  is inserted into each hole  624  of the insert-component  620  (see  FIGS. 5A and 5B ). Finally the insert-component  624  and pin insert(s)  700  are locked into place using a suitable locking system. 
     After the mold is assembled, a standard injection molding process is used to form the lid. 
     III. Uses for the Containers 
     The containers are designed to be used to store and transport food. However, the containers may be used to store a variety of non-food materials. In the preferred embodiment, the containers are designed for use by restaurants, particularly for sending food home with a customer, e.g. “take-out” food. Containers with lids containing one or more vents are particularly suitable for transporting and/or storing hot food. 
     In one embodiment, the container includes a base and a lid having at least one vent on the top of the lid. If hot food is placed inside the container, steam will rise from the hot food inside of the container, and the vapor pressure inside the container will increase, causing the lid to deform and rise up. If at least one container is stacked on top of the container with the hot food (the “first container”), then deformation of the lid on the first container can cause displacement of the container placed on top of the lid (the “second container”), possibly spilling the contents of the second container. To prevent this from occurring, a user can apply a downward pressure, typically using his/her finger, on the vent in the lid of the container, thereby opening the dividers in the vent and allowing the steam to escape from the container. As the steam escapes, the pressure inside the container equilibrates with the ambient pressure, thereby preventing deformation of the lid and/or enabling the lid to return to its original shape. 
     In a preferred embodiment, the dividers self-seal, when the pressure inside the container equilibrates with the ambient pressure. 
     In another embodiment, the containers contain an indicator or descriptive element on the top of the lid. These containers are particularly useful for stores and/or restaurants to identify themselves and/or the contents of the food to the customer. Optionally, the lid also contains one or more vents to be used as described above to prevent deformation of the lid and/or return the lid to its original shape, when the container is used to transport and/or store hot food. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. Publications cited herein and the materials for which they are cited are specifically incorporated by reference. 
     Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.