Abstract:
The present invention relates to a food packaging material for packing food, more particularly to a food packaging material having a uniform coating of oil, a method of manufacturing the same, and a mold for manufacturing the same. The food packaging material includes a plurality of grooves formed on one surface of the food packaging material; and an oil layer uniformly applied to the one surface of the food packaging material, being put into the grooves. According to the present invention, there are provided a food packaging material which continuously maintains a uniform coating of oil and thus minimizes sticking of contents to a surface of the packaging material, a method of manufacturing the same, and a mold for manufacturing the same.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is divisional application of U.S. application Ser. No. 14/344,215 filed Mar. 11, 2014, which is a national stage of International Application No. PCT/KR2011/008064, filed Oct. 27, 2011, which claims the benefit of Korean Application No. 10-2011-0095170, filed Sep. 21, 2011, in the Korean Intellectual Property Office. All disclosures of the document(s) named above are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a food packaging material for packing food, more particularly to a food packaging material having a uniform coating of oil, a method of manufacturing the same, and a mold for manufacturing the same. 
         [0004]    2. Description of the Related Art 
         [0005]    Food packaging materials are used to package food. Food packaging materials have been improved to enhance stability of food storage, whereas a problem that contents stick to a food packaging material is not solved. 
         [0006]    For example, as to a food packaging material used as a top of a spoonable fermented milk product, when a consumer buys a fermented milk product and pulls the food packaging material, some contents stick to the food packaging material. In this case, consumers mostly give up the contents on the packaging material. The same problem occurs with respect to a food packaging material for packaging high-viscosity retort food, such as retort curry. 
         [0007]      FIG. 1  illustrates a conventional food packaging material. In order to solve the above problem, there is a try at coating the surface of a food packaging material  10  with edible oil. 
         [0008]    In this case, however, as shown in  FIG. 1 , force caused by surface extension of oil acts in arrow directions, so that the edible oil forms a plurality of agglomerated oil drops  20 . When the edible oil is not uniformly applied, contents are not prevented from sticking to the packaging material. 
       SUMMARY OF THE INVENTION 
     Technical Problem 
       [0009]    The present invention is directed to solve problems mentioned above and provides a food packaging material which continuously maintains a uniform coating of oil and thus minimizes sticking of contents to a surface of the packaging material, a method of manufacturing the same, and a mold for manufacturing the same. 
       Solution to Problem 
       [0010]    In accordance with an aspect of the present invention, a method of manufacturing a food packaging material having a uniform coating of oil includes (a) preparing a mold including a plurality of prism bodies and (b) forming a plurality of grooves on one surface of a food packaging material corresponding to the prism bodies by pressing the mold to the food packaging material. 
         [0011]    The method may further include (c) applying an oil layer to the one surface of the food packaging material on which the grooves are formed. 
         [0012]    The preparing the mold (a) may include (a-1) preparing a first metal layer, (a-2) depositing a photoresist layer on the first metal layer, (a-3) forming a plurality of photoresist holes disposed at predetermined intervals by patterning the photoresist layer, and (a-4) forming the prism bodies on the first metal layer. 
         [0013]    The photoresist holes may have a cylindrical shape or a polygonal prism shape and are arranged in a grid pattern. 
         [0014]    The prism bodies may be formed on the first metal layer by galvanoplasty. 
         [0015]    The prism bodies may be formed on the first metal layer disposed in the photoresist holes. 
         [0016]    The first metal layer may be deposited on a silicon layer disposed under the first metal layer. 
         [0017]    The first metal layer may include titanium. 
         [0018]    The prism bodies may include nickel or gold. 
         [0019]    In accordance with another aspect of the present invention, a mold for manufacturing a food packaging material having a uniform coating of oil includes a first metal layer, a photoresist layer formed on the first metal layer and including a plurality of photoresist holes disposed at predetermined intervals, and a plurality of prism bodies formed on the first metal layer disposed in the photoresist holes. 
         [0020]    The prism bodies may have a cylindrical shape or a polygonal prism shape and are arranged in a grid pattern. 
         [0021]    The first metal layer may be deposited on a silicon layer disposed under the first metal layer. 
         [0022]    The first metal layer may include titanium. 
         [0023]    The prism bodies may include nickel or gold. 
         [0024]    In accordance with still another aspect of the present invention, a food packaging material having a uniform coating of oil to package food includes a plurality of grooves formed on one surface of the food packaging material and an oil layer uniformly applied to the one surface of the food packaging material, being put into the grooves. 
         [0025]    The grooves may be arranged at predetermined intervals in a grid pattern. 
         [0026]    The grooves may have a cylindrical shape or a polygonal prism shape. 
       ADVANTAGEOUS EFFECTS OF INVENTION 
       [0027]    As described above, the present invention provides a food packaging material which continuously maintains a uniform coating of oil and thus minimizes sticking of contents to a surface of the packaging material, a method of manufacturing the same, and a mold for manufacturing the same. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0029]      FIG. 1  illustrates a conventional food packaging material; 
           [0030]      FIG. 2 a    is a perspective view of a food packaging material having a uniform coating of oil according to an exemplary embodiment of the present invention; 
           [0031]      FIG. 2 b    is a cross-sectional view of the food packaging material of  FIG. 2 , taken along line A 2 -B 2 ; 
           [0032]      FIGS. 3 a  to 3 d    illustrate a method of manufacturing the food packaging material of  FIG. 2 ; and 
           [0033]      FIGS. 4 a  to 7 b    illustrate a process of manufacturing a mold used in a method of manufacturing a food packaging material. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0034]    Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 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. 
         [0035]    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. Description of unnecessary parts or elements may be omitted for clarity and conciseness, and like reference numerals in the drawings refer to like elements. 
         [0036]    Hereinafter, a food packaging material having a uniform coating of oil, a method of manufacturing the same, and a mold for manufacturing the same according to exemplary embodiments of the present invention will be described with reference to the accompanying drawings. 
         [0037]      FIG. 2 a    is a perspective view of a food packaging material having a uniform coating of oil according to an exemplary embodiment of the present invention, and  FIG. 2 b    is a cross-sectional view of the food packaging material of  FIG. 2 , taken along line A 2 -B 2 . 
         [0038]    Referring to  FIGS. 2 a  and 2 b   , the food packaging material having the uniform coating of oil (hereinafter, “food packaging material”)  100  according to the exemplary embodiment of the present invention is used to package food, for example, used as a top for a fermented milk product or a packaging material for retort food. The food packaging material  100  includes a plurality of grooves  110  which are formed on one side thereof for a uniform coating of oil and an oil layer  120 . 
         [0039]    The grooves  110  may be formed in a minute size by microelectromechanical systems (MEMS), which will be described in detail. 
         [0040]    The oil layer  120  is applied to a surface of the food packaging material  100  having the grooves  110  in order to prevent food from sticking to the surface of the food packaging material  100 . 
         [0041]    In particular, the oil layer  120  is put into the respective grooves  110  to relieve force due to surface tension of oil, described with reference to  FIG. 1 , and thus the oil layer  120  is not separately dispersed as agglomerated oil drops but is uniformed applied. 
         [0042]    Further, as compared with the packaging material of  FIG. 1 , a coating of the oil layer  120  is stably maintained for a long time, and the oil layer  120  in the grooves  110  functions to push water or food, so that the food does not stick to the packaging material. Accordingly, a minimum amount of food sticks to the packaging material. 
         [0043]    Also, the uniformly applied oil layer  120  prevents the food packaging material  100  from being in direct contact with food, thereby avoiding harmful effects transmitted from the food packaging  100 . 
         [0044]    Here, the grooves  101  may be arranged at predetermined intervals in a grid pattern in order to uniformly form the oil layer  120 , shown in  FIG. 2   a.    
         [0045]    Further, the grooves  110  may have a cylindrical shape or various polygonal prism shapes, such as a triangular prism, a rectangular prism, a hexagonal prism, etc., and may have the same height. 
         [0046]      FIGS. 3 a  to 3 d    illustrate a method of manufacturing the food packaging material of  FIG. 2   a.    
         [0047]    Referring to  FIGS. 3 a  to 3 d   , the method of manufacturing the food packaging material according to the present embodiment includes (a) preparing a mold and (b) forming grooves, and may further include (c) applying an oil layer. 
         [0048]    Referring to  FIG. 3 a   , in the preparing the mold (a), a mold  200  having a plurality of prism bodies  210  and a food packaging material  100  are prepared. 
         [0049]    Here, the grooves  110  are not yet formed in the food packaging material  100 , which is formed of synthetic resins, such as polypropylene (PP) and polyethylene terephthalate (PET). 
         [0050]    Further, the prism bodies  210  are provided to form the grooves  110  and formed in a corresponding shape to the grooves  110 . Thus, the prism bodies  210  may have a cylindrical or polygonal prism shape and be arranged in a grid pattern. 
         [0051]    Referring to  FIG. 3 b   , in the forming the grooves (b), the food packaging material  100  and the mold  200  are arranged, and then the mold  200  is pressed to the food packaging material  100 , thereby forming a plurality of grooves  110  on one surface of the food packaging material  100  corresponding to the prism bodies  210 . 
         [0052]    That is, when the mold  200  is joined to the food packaging material  100  using heat and pressure, parts of the food packaging material  100  corresponding to the prism bodies  210  are pressed by the prism bodies  210 , thereby forming the grooves  110 . 
         [0053]    These grooves  110  are formed based on a shape of the prism bodies  210 . Thus, when the prism bodies  210  have a cylindrical shape, the grooves  110  are formed in a cylindrical shape. When the prism bodies  210  have a polygonal prism shape, the grooves  110  are formed in a polygonal prism shape. 
         [0054]    Referring to  FIGS. 3 c  and 3 d   , in the applying the oil layer (c), the mold  200  bonded to the food packaging material  100  is removed, and then the oil layer  120  is applied to the one surface of the food packaging material  100  on which the grooves  110  are formed. 
         [0055]      FIGS. 4 a  to 7 b    illustrate a process of manufacturing a mold used in a method of manufacturing a food packaging material. With reference to  FIGS. 4 a  to 7 b   , the method of manufacturing the food packaging material is described in detail. 
         [0056]    According to an exemplary embodiment of the present invention, (a) preparing a mold includes (a-1) preparing a first metal layer, (a-2) depositing a photoresist layer, (a-3) forming photoresist holes, and (a-4) forming prism bodies. 
         [0057]      FIG. 4 a    illustrates the preparing the first metal layer (a-1), and  FIG. 4 b    is a cross-sectional view of  FIG. 4 a   , taken along line A 4 -B 4 . 
         [0058]    Referring to  FIGS. 4 a  and 4 b   , in the preparing the first metal layer (a-1), a silicon layer  300  is prepared, and a first metal  310  is formed on the silicon layer  300 . 
         [0059]    Here, The first metal layer  310  may be formed on a silicon layer  300  in order to uniformly form the first metal layer  310 . 
         [0060]    Further, the first metal layer  310  may include titanium and may also include other metals. 
         [0061]      FIG. 5 a    illustrates the depositing the photoresist layer (a-2), and  FIG. 5 b    is a cross-sectional view of  FIG. 5 a   , taken along line A 5 -B 5 . 
         [0062]    Referring to  FIGS. 5 a  and 5 b   , in the depositing the photoresist layer (a-2), a photoresist layer  320  is deposited on the first metal layer  310 . 
         [0063]    Here, the photoresist layer  320  may include a positive photoresist or a negative photoresist. For example, AZ9260 may be used as a positive photoresist, and SU-8 may be used as a negative photoresist. 
         [0064]      FIG. 6 a    illustrates the forming the photoresist holes (a-3), and  FIG. 6 b    is a cross-sectional view of  FIG. 6 a   , taken along line A 6 -B 6 . 
         [0065]    Referring to  FIGS. 6 a  and 6 b   , in the forming the photoresist holes (a-3), the photoresist layer  320  deposited on the first metal layer  310  is patterned. Thus, a plurality of photoresist holes  330  disposed at predetermined intervals are formed in the photoresist layer  320 . 
         [0066]    That is, the photoresist holes  330  may be formed in the photoresist layer  320  by exposing and developing processes of photolithography. 
         [0067]    Here, the photoresist holes  330  may have a cylindrical shape or a polygonal prism shape and be arranged in a grid pattern. The first metal layer  310  under the photoresist holes  330  is exposed to the outside. 
         [0068]      FIG. 7 a    illustrates the forming the prism bodies (a-4), and  FIG. 7 b    is a cross-sectional view of  FIG. 7 a   , taken along line A 7 -B 7 . 
         [0069]    Referring to  FIGS. 7 a  and 7 b   , in the forming the prism bodies (a-4), prism bodies  210  are formed in the photoresist holes  330 . As the first metal layer  310  is exposed to the outside through the photoresist holes  330 , the prism bodies  210  are formed on the first metal layer  310 . Thus, the mold  200  including the prism bodies  210  is completely formed. 
         [0070]    Here, the prism bodies  210  may be formed by galvanoplasty. Thus, the prism bodies  210  may be formed on the first metal layer  310  and disposed in the photoresist holes  300 . 
         [0071]    In this case, since the photoresist layer  320  is nonconductive, the prism bodies  210  of a metal material grows only on the first metal layer  310  having conductivity. 
         [0072]    To this end, the prism bodies  210  may be formed of nickel (Ni) or gold (Au) or may also include other metals. 
         [0073]    Using MEMS, a plurality of prism bodies  210  having a considerably minute size may be formed on the mold  200 , and accordingly the food packaging material  100  may also be formed with considerably minute grooves  110 . 
         [0074]    The mold  200  to manufacture the food packaging material according to the embodiment of the present invention may be manufactured by the above described process, and thus the mold  200  includes the first metal layer  310 , the photoresist layer  320 , and the prism bodies  210  (see  FIGS. 7 a  and 7 b   ). 
         [0075]    The first metal layer  310  may be formed on a silicon layer  300 , and the photoresist layer  320  having the plurality of photoresist holes  330  is disposed on the first metal layer  310 . 
         [0076]    The prism bodies  210  are formed on the first metal layer  310  disposed in the photoresist holes  330  to be exposed to the outside. 
         [0077]    The mold  200  thus manufactured facilitates formation of the minute grooves  110  in the food packaging material  100 , so that each food packaging material  100  is not involved in a complicated process including photolithography. Thus, costs, time, and labor force involved in manufacture may be reduced. 
         [0078]    Although the spirit of the present invention was described in detail with reference to the preferred embodiments, it should be understood that the embodiments are provided only for explaining the present invention and the present invention is not limited thereto. Further, it should be understood that the present invention may be modified in various ways by those skilled in the art, without departing from the scope of the present invention. The scope of the present invention described above is determined by the following claims and not limited to the detailed description described herein, and equivalent changes and modifications within claims are included in the spirit and scope of the present invention.