Patent Publication Number: US-2012031799-A1

Title: Food storage container

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0075699, filed on Aug. 5, 2010, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field of the Invention 
     The embodiment relates to a food storage container, and more particularly, to a food storage container which has an improved film structure as compared with a conventional complicated film structure and has a high oxygen barrier performance. 
     2. Discussion of Related Art 
     There are various types of retort pouches being on the market. Generally, a retort pouch is to preserve food for a long time, being blocked from air and light, and is manufactured as follows: cooked and processed food is sealed into a container, followed by heating and sterilization at a high temperature via a retort sterilization process. The retort sterilization process includes a high-retort sterilization, performed at 125° C. or more, a standard retort sterilization, performed at 121° C., a semi-retort sterilization, performed around 110° C., and the like. In addition to the retort sterilization process, there are used various methods, such as a heating sterilization of sterilizing with heat of 100° C. or less for a predetermined period of time, a hot-filling in which contents are sterilized at a high temperature and sealed in a container, or the like. Further, non-sterilization is performed on products which do not need sterilizing. 
     In order to preserve food sterilized through the above processes or non-sterilized for a long time, a food storage container has a high oxygen barrier performance. Conventionally, in order to have a high oxygen barrier performance, a film having a high barrier performance is in-molded on an outside of the container, but a portion, such as a corner of the container, may not be in-molded to reduce oxygen barrier performance. 
     Further, a method of providing oxygen barrier performance to a container using injection resin having a high barrier performance is used, but the injection resin is expensive, and oxygen barrier performance decreases when the resin having the high barrier performance is not uniformed distributed. 
     In addition, there are more methods, such as a method that a high barrier performance sheet is thermally molded into a container shape and inserted into an injection container, a method of inserting a film into an inside of a container and injecting, a method of thermally molding a high barrier performance sheet of ethylene vinyl alcohol (EVOH) or meta-xylylene diamine (MXD-6), or the like. 
     In the method that the high barrier performance sheet is thermally molded into the container shape and inserted into the injection container, thermally molding the high barrier performance sheet and injection are separately performed to bring about a complicated process, and an entire thickness of the container becomes thick due to the thermally molded sheet. 
     In the method of inserting the film into the inside of the container and injecting, the film has a complicated structure so that a vacuum is not formed when the film is attached to the container, and thus a manufacturing process is difficult. Moreover, since the film is shaped in advance and inserted, an additional manufacturing process is needed. 
     In the thermally molded container of EVOH or MXD-6, oxygen barrier performance decreases in a sterilization process and is not uniform depending on a difference in thickness of the container to reduce an expiration data. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is to provide a food storage container in which a film to be attached to an inside of the container is divided into two sheets and attached, so that a conventional complicated film structure is improved, a process of shaping the film is not necessary, and manufacturing costs are reduced. 
     Further, an aspect of the present invention is to provide a food storage container in which a film forms a first overlapping part and a second overlapping part to be closely attached to an inside of the container although the film is divided into two sheets, so that oxygen barrier performance is improved to preserve food in the container for a long time. 
     According to an aspect of the present invention, there is provided a food storage container including a container body including a bottom part and a lateral part to form an interior space, a bottom film attached to the bottom part, and a lateral film forming a first overlapping part where the lateral film overlaps with the bottom film and a second overlapping part where an end portion overlaps with another end portion, and being attached to the lateral part. 
     The container body may be integrated with the respective films by insert molding. 
     The bottom film and the lateral film each may include a lower layer formed of polypropylene (PP), at least one oxygen barrier resin layer disposed on the lower layer, and an upper layer disposed on the oxygen barrier resin layer and formed of PP. 
     The oxygen barrier resin layer may include polyethylene terephthalate (PET). 
     The bottom film and the lateral film each may further include an ivory white layer disposed between the lower layer and the oxygen barrier resin layer and formed of ivory white PP or ivory white PET. 
     The container body may further include a flange extending outwards from an upper portion of the lateral part, the lateral film may be attached to an upper surface of the flange as well as to the lateral part, and the food storage container may further include a lead film attached to the lateral film on the upper surface of the flange. 
     The lead film may include a lower layer formed of PP, at least one oxygen barrier resin layer disposed on the lower layer, and an upper layer disposed on the oxygen barrier resin layer and formed of PP. 
     The oxygen barrier resin layer may include PET. 
     The oxygen barrier resin layer may have an oxygen transmission rate of 0.07 cc/m 2 ·day·atm to 0.09 cc/m 2 ·day·atm. 
     Display information may be printed on a lower surface of the ivory white layer. 
     As described above, exemplary embodiments of the present invention provides a food storage container in which a film to be attached to an inside of the container is divided into two sheets and attached, so that a conventional complicated film structure is improved, a process of shaping the film is not necessary, and manufacturing costs are reduced. 
     Further, exemplary embodiments of the present invention provide a food storage container in which a film forms a first overlapping part and a second overlapping part to be closely attached to an inside of the container although the film is divided into two sheets, so that oxygen barrier performance is improved to preserve food in the container for a long time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention. 
         FIG. 1  is a cross-sectional view of a food storage container according to an exemplary embodiment of the present invention; 
         FIG. 2A  is an enlarged view of a part A of  FIG. 1 ; 
         FIG. 2B  illustrates a first overlapping part; 
         FIGS. 3A and 3B  illustrate a second overlapping part; 
         FIG. 4  is a cross-sectional view of a bottom film and a lateral film; and 
         FIG. 5  is a cross-sectional view of the food storage container further including a flange. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. 
     Hereinafter, the present invention will be described in detail with reference to the accompanying drawings illustrating a food storage container according to exemplary embodiments. 
       FIG. 1  is a cross-sectional view of a food storage container according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , the food storage container according to the present embodiment includes a container body  10 , a bottom film  21 , and a lateral film  22 . 
     The container body  10  forms an interior space  16  in which preserved food is put, and includes a bottom part  12  and a lateral part  14  to form the interior space  16  which is open upwards. 
     The bottom part  12  may be formed in a plate shape and may be slightly modified, for example, bent, grooved, or the like. 
     The lateral part  14  is formed to extend upwards from an edge of the bottom part  12  and functions to close a lateral side of the container body  10 . 
     The bottom film  21  is attached to the bottom part  12  on an upper side of the bottom part  12 , as shown in  FIG. 1 . 
     The lateral film  22  is attached to the lateral part  14  on an internal side of the lateral part  14 , as shown in  FIG. 1 . 
     The bottom film  21  and the lateral film  22  form a first overlapping part and a second overlapping part to eliminate a portion where the films are not attached in the container body  10 . 
     The container body  10  may be formed of synthetic resins, such as transparent plastic, and is integrated with the bottom film  21  and the lateral film  22  by a film insert molding. 
     The film insert molding is a process that by inserting a preformed film into a mold before injection molding, the film and a molded part are integrated into a product, simultaneously with injection. 
       FIG. 2A  is an enlarged view of a part A of  FIG. 1 ,  FIG. 2B  illustrates the first overlapping part, and  FIGS. 3A and 3B  illustrate the second overlapping part. Hereinafter, the first overlapping part  31  and the second overlapping part  32  are described further with reference to  FIGS. 2A to 3B . 
     First, the first overlapping part  31  is a portion where the lateral film  22  overlaps with the bottom film  21  and is formed to eliminate a vacuum, where the film is not attached, formed between the lateral film  22  and the bottom film  21 . 
     Referring to  FIG. 2A , the lateral film  22  is disposed over the bottom film  21 , but the lateral film  22  may be disposed under the bottom film  21 . 
     In  FIG. 2A , a space formed between the bottom film  21  and the lateral part  14  is exaggerated for clarity. Practically, each film is considerably thin and is thermally attached to the inside of the container body  10 , and thus the space due to the first overlapping part  31  is greatly small or the space may not exist. 
     Further, in  FIGS. 2A and 2B , the first overlapping part  31  is formed on the lateral part  14  but may be formed in different positions, such as around a corner between the bottom part  12  and the lateral part  14 , on the bottom part  12 , or the like. 
     The second overlapping part  32  is a portion where the lateral film  22  overlaps with itself, that is, a portion where one end portion  221  of the lateral film  22  overlaps with another end portion  222 . 
     The second overlapping part  32  is formed to closely cover the entire lateral part  14  without a vacuum being formed when the lateral film  22  is attached to the lateral side  14 . 
     The first overlapping part  31  and the second overlapping part  32  are attached by heat in an injection molding process, wherein the bottom film  21  is thermally attached to the lateral film  22  in the first overlapping part  31 , and the one end portion  221  is thermally attached to the other end portion  222  in the second overlapping part  32 . 
     Thus, a film to be attached to the inside of the container body  10  is divided into two sheets to be attached to the bottom part  12  and the lateral part  14 , respectively, thereby improving a conventional complicated film structure, not involving a manufacturing process of shaping a film, and reducing manufacturing costs. 
     Further, although the film is divided into two sheets, the first overlapping part  31  and the second overlapping part  32  are formed so that the film is closely attached to the inside of the container body  10 . Accordingly, oxygen barrier performance is enhanced to preserve food in the container for a long time. 
     Although  FIGS. 2B and 3B  show the respective overlapping parts  31  and  32  being formed straightly and having a regular width, a size and a shape of the respective overlapping parts  31  and  32  may be changed depending on a size and a shape of the respective films  21  and  22 , a size and a shape of the container body  10 , or the like. 
       FIG. 4  is a cross-sectional view of the bottom film and the lateral film. 
     Referring to  FIG. 4 , in the food storage container according to the exemplary embodiment, the bottom film  21  and the lateral film  22  each include a lower layer  51 , an oxygen barrier resin layer  53 , and an upper layer  54  which are sequentially disposed. 
     Further, the respective films  21  and  22  may further include an ivory white layer  52  disposed between the lower layer  51  and the oxygen barrier resin layer  53 . The ivory white layer  52 , which is ivory white, is included to prevent a color of food in the container from being seen from the outside. The ivory white layer  52  may be formed of ivory white polypropylene (PP) or ivory white polyethylene terephthalate (PET). 
     Display information may be printed on a lower surface of the ivory white layer  52 . The display information printed on the lower surface of the ivory white layer  52  includes pictures and forms including patterns, designs, and characters, such as flowers and butterflies, product related information, such as barcodes and labels, letters, or the like, but is not limited thereto. 
     The display information is printed on an inside of a film to be insert-molded and is exposed to the outside through the container body  10 , and thus damage which may occur when a sticker or label is attached to an outside of the container is prevented in designing the container. 
     Here, the lower layer  51  and the upper layer  54  may be formed of PP. 
     Further, the oxygen barrier resin layer  53  may be formed of PET. A plurality of oxygen barrier resin layers  53  may be included in the respective films  21  and  22  to improve oxygen barrier performance, and an oxygen transmission rate (OTR) may be 0.07 cc/m 2 ·day·atm to 0.09 cc/m 2 ·day·atm. 
     An OTR is measured on the container of the present invention and other containers using an oxygen permeation rate tester (OX-TRAN, a registered trademark, manufactured by MOCON, Inc.). 
     Experimental objects: A container of the present invention, a container having a general barrier film in-molded on an outside, a thermally molded container of ethylene vinyl alcohol (EVOH), and a thermally molded container of meta-xylylene diamine (MXD-6). 
     Experimental conditions: Contents (food) are put in an object container and retort-sterilized, after which an OTR is measured at 23° C. and a relative humidity (RH) of 0% within 6 hours. 
     An OTR is measured as follows (cc/pkg/24 h·atm). 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Container of 
                 General barrier 
                   
                   
               
               
                   
                 the present 
                 film in-molded 
                 EVOH 
                 MXD-6 
               
               
                   
                 invention 
                 container 
                 container 
                 container 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Before retort 
                 0.002 
                 0.8 
                 0.004 
                 0.005 
               
               
                 sterilization 
               
               
                 After retort 
                 0.003 
                 1.0 
                 0.12 
                 0.03 
               
               
                 sterilization 
               
               
                   
               
            
           
         
       
     
     As shown in Table 1, the container of the present invention has a lower OTR before retort sterilization than the other containers. 
     Further, the other containers have a considerably increased OTR after retort sterilization, while the container of the present invention has a slightly increased OTR after retort sterilization. 
     Thus, the container of the present invention has an OTR before retort sterilization slightly different from the other containers, but has an OTR after retort sterilization considerably different from the other containers. 
     Accordingly, the container of the present invention still has a superior oxygen barrier performance after retort sterilization as compared with the other containers. 
       FIG. 5  is a cross-sectional view of the food storage container further including a flange. 
     Referring to  FIG. 5 , the container body  10  further includes a flange  18  extending outwards from an upper end portion of the lateral part  14 . 
     The lateral film  22  is attached to an upper surface of the flange  18  as well as to the lateral part  14 . That is, the lateral film  22  covering the lateral part  14  extends to the flange  18  to cover the upper surface of the flange  18 . Here, the lateral film  22  may form the second overlapping part  32  on the upper surface of the flange  18  to closely cover the upper surface of the flange  18 . 
     Thus, a lead film  60  is thermally attached to the lateral film  2 , so that food in the container is thoroughly blocked from the outside due to the film having a high oxygen barrier performance. 
     The lead film  60  functions to seal the interior space of the container body  10  and is attached to the lateral film  22  disposed on the upper surface of the flange  18 . 
     The lead film  60  may have the same configuration as the respective films  21  and  22  in order to prevent oxygen from permeating the container. 
     That is, the lead film  60  includes a lower layer  51  and an upper layer  54  which are formed of PP, and an oxygen barrier resin layer  53  disposed between the lower layer  51  and the upper layer  54 . 
     Further, the oxygen barrier resin layer  53  may be formed of PET, and a plurality of oxygen barrier resin layers  53  may be included to improve oxygen barrier performance. 
     While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.