Patent Publication Number: US-2012033899-A1

Title: Zipper tape and zipper-tape-equipped bag

Description:
TECHNICAL FIELD 
     The present invention relates to a zipper tape and a zipper-tape-equipped bag. 
     BACKGROUND ART 
     A bag that can be freely opened and closed by providing, at its opening portion, a belt-shaped biting tool (zipper tape) comprising a male member and a female member is used principally in the food industry. Such a bag is also used as a bag for bedding or clothing. 
     Patent document 1 has disclosed a zipper having a male member  10  and a female member  20  that bite each other, wherein pinch valves  25  and  26  are provided between claw members  22  and  24  of the female member  20 , as shown in  FIG. 6 . When biting, the pinch valves  25  and  26  pinch and lift a head  12  of the male member  10  so that the male member  10  and the female member  20  are kept in close contact. 
     However, the sealing performance of this zipper is inadequate because the male and female members are not in surface contact. 
     Patent document 2 has disclosed a zipper comprising a male member  30  and a female member  40  as shown in  FIG. 7 . In this zipper, a head  32  of the male member  30  comes into surface contact with a part of the inner side surface of a claw member  42  of the female member  40  and a part of the inner side surface of a claw member  44  of the female member  40 , and the claw members  42  and  44  clamp and seal in the head  32 . 
     This zipper is improved in sealing performance because the male and female members are in surface contact, but this zipper has the following various problems. 
     As the head of the male member is clamped by the tips of the claw members located apart from the base portion of the female member, clamping force is weak. If a load is applied to the tips of the claw members of the female member, the distance between the claw members increases, and the sealing performance may be impaired. When the claw members of the female member are so long as to touch the shaft of the male member, the claw members of the female member tend to be expanded at the boundary (the expanded claw members of the female member) of a fitted portion and an unfitted portion if the zipper is kept open for a long time, so that the sealing performance may decrease. The head of the male member is arc-shaped, which makes it difficult to align and fit the male and female members. If the zipper deforms at a side seal during the production of a bag, the sealing performance may be impaired, so that an advanced bag production technique is required during the bag production.
     [Patent document 1] Japanese Patent Publication Laid-open No. 63-96040   [Patent document 2] Japanese Patent Publication Laid-open No. 7-309351   

     DISCLOSURE OF THE INVENTION 
     A zipper tape having high sealing performance is provided. 
     According to the present invention, a zipper tape and a zipper-tape-equipped bag below are provided. 
     1. A zipper tape includes a male member and a female member that bite each other, 
     the male member having a head, a projection at the tip of the head, and a recess located at a connecting portion between the projection and the tip of the head, 
     the female member having first and second claw members facing each other, a valley between the first and second claw members, and a pair of protrusions located at the top of the valley, 
     wherein when the male member and the female member bite each other, at least a part of the inner surface of the first claw member of the female member and at least a part of the inner surface of the second claw member of the female member come into surface contact with at least a part of the surface of the head of the male member, and 
     the valley of the female member receives the projection of the male member, and the protrusions of the female member fit into the recess of the male member. 
     2. The zipper tape according to 1, wherein the width of the projection of the male member is greater than the distance between the pair of protrusions of the female member, and smaller than the distance between the tiptops of the first and second claw members of the female member. 
     3. The zipper tape according to 1 or 2, wherein the female member has clasps projecting from the tips of the first and second claw members so as to face each other, and the length of the clasp is equal to or less than half the length of a clasp reception formed by the rear surface of the head. 
     4. A bag equipped with the zipper tape according to any one of 1 to 3. 
     According to the present invention, a zipper tape having high sealing performance can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing a zipper tape comprising a male member and a female member according to one embodiment of the present invention; 
         FIG. 2  is a diagram showing how the male member and the female member of  FIG. 1  bite each other; 
         FIG. 3  is a diagram showing the dimensions of parts of the male member of  FIG. 1 ; 
         FIG. 4  is a diagram showing the dimensions of parts of the female member of  FIG. 1 ; 
         FIG. 5  is a photograph of a zipper tape manufactured in Example 1; 
         FIG. 6  is a diagram showing a conventional zipper tape comprising a male member and a female member; 
         FIG. 7  is a diagram showing another conventional zipper tape comprising a male member and a female member; 
         FIG. 8  is a diagram showing the dimensions of parts of a male member used in Comparative example 1; 
         FIG. 9  is a diagram showing the dimensions of parts of a female member used in Comparative example 1; 
         FIG. 10  is a diagram showing the dimensions of parts of a male member used in Comparative example 2; and 
         FIG. 11  is a diagram showing the dimensions of parts of a female member used in Comparative example 2. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, an embodiment(s) of the present invention will be described with reference to the drawings. However, the embodiment(s) is illustrative only, and the present invention is not limited to the embodiment(s). 
     A zipper tape according to one embodiment of the present invention is shown in  FIG. 1 . This zipper tape comprises a male member  100  and a female member  200  that bite each other. 
     The male member  100  includes a base  110 , a head  120 , and a rod-like coupling portion  130  that couples the head  120  to the base  110 . The head  120  is substantially semispherical, and has a tip  122  and a rear surface  124 . The substantially semispherical shape not only includes a semispherical shape but also includes, for example, a heart shape and an arrowhead shape. 
     The rear surface  124  of the head  120  is greater than the section of the coupling portion  130 , and the coupling portion couples to substantially the center of the rear surface of the head. A part of the rear surface  124  of the head that is not coupled to the coupling portion  130  forms clasp receptions  124 . 
     The tip  122  of the male member  100  has a projection  126 . A recess  128  is present in a connecting portion between the tip  122  and the projection  126 , that is, at the base of the projection  126 . 
     The female member  200  includes a base  210 , arc-shaped first and second claw members  220  and  230  facing each other, and clasps  222  and  232  projecting from the tips of the first and second claw members  220  and  230  so as to face each other. The clasps  222  and  232  are smaller in length than the clasp receptions  124  of the male member. A valley  240  for receiving the projection  126  at the tip of the male member is present between the first and second claw members  220  and  230 . A pair of protrusions  242  are present at the top of the valley  240 , that is, at the bases of the claw members  220  and  230 . 
     As shown in  FIG. 2 , if the male member  100  is inserted into the female member  200 , the projection  126  at the tip of the female member comes into the valley  240  between the first and second claw members, and the pair of protrusions  242  of the female member fit into the recesses  128  of the male member. Further, at least a part of the inner surface of the first claw member  220  of the female member and at least a part of the inner surface of the second claw member  230  of the female member, that face each other, come into surface contact with at least a part of the surface of the head  120  of the male member. In this condition, sealing performance is enhanced. 
     Furthermore, clamping force for clamping the projection  126  at the head of the male member is strong in the valley  240  in the female member. 
     Moreover, in the male member  30  shown in  FIG. 7 , the tip of the head  32  is in a flat arc shape, and may therefore come out of position and out of track. In contrast, according to the present embodiment, the projection  126  is formed at the tip  122 , and the clasps  222  and  233  guide this projection  126 , so that the male member  100  and the female member  200  can be easily aligned. 
     When the male member  100  and the female member  200  bite each other, the clasps  222  and  232  of the female member come into contact, preferably, surface contact with the rear surface  124  of the male member. This further enhances sealing performance. 
     In the present embodiment, the width a of the projection of the male member is preferably greater than the distance A of the protrusions of the female member (see  FIGS. 3 and 4 ). If the width a is greater than the distance A, the female member lifts the male member, and contact pressure between the protrusions  242  and the recesses  128  and contact pressure between the clasps  222  and  232  and the clasp receptions  124  increase. 
     The width a of the projection of the male member is preferably smaller than a distance E between the tiptops of the claw members of the female member (see  FIGS. 3 and 4 ). If the width a is smaller than the distance E, the male and female members are easily aligned when fitted together, and is easily fitted together. 
     The length c from the rear end of the male member to the front end of the male member is preferably greater than the length C from the top of the valley of the female member to the base of the clasp (see  FIGS. 3 and 4 ). If the length c is greater than the length C, the head lifts the clasps of the claw members, and contact pressure between the clasps and the clasp receptions increases. 
     Here, c is not easily recognized in the case of a curve shown in  FIG. 5 , inflection points of R of the projection and R of the recess are defined as ends. 
     The length D from the clasp of the female member is preferably equal to or less than half the length d of the clasp reception of the male member (see  FIGS. 3 and 4 ). If the clasp is shorter than the clasp reception, the claw members of the female member do not tend to be expanded and the sealing performance does not deteriorate even if the zipper is kept open for a long time. 
     In the configuration described above, dotted circular marks in  FIG. 2  indicate surface contact, and solid circular marks indicate contact pressure. 
     Here, if the width b of the head of the male member is greater than the distance B of the inner surfaces of the claw members of the female member (see  FIGS. 3 and 4 ), the contact pressure of surface contact between the claw members of the female member and the head of the male member preferably increases. 
     The zipper tape according to the present invention may include the arrangement of pairs of male and female zippers. 
     The material of the zipper tape may be selected from materials that have heretofore been used for zipper tapes, for example, low-density polyethylene, straight-chain low-density polyethylene, ethylene-vinyl acetate copolymer, and polypropylene. For a high-sealing zipper, a soft resin such as polyethylene or ethylene copolymer is particularly preferable. 
     The configuration described above allows the zipper tape according to the present embodiment to maintain sealing performance in various conditions in which the zipper tape is used. As long as the protrusions  242  are in contact with the projection  126  or the recesses  128 , this zipper tape maintains sealing performance, and is therefore easily squashed. 
     A bag according to the present invention is equipped with the zipper tape described above. 
     EXAMPLES 
     Example 1 
     A zipper tape provided with two biting portions shown in  FIGS. 1 to 4  was manufactured from low-density polyethylene (density 926 kg/m 3 ). 
     The dimensions of parts of the biting portions were as follows: a=0.63 mm, A=0.55 mm, b=1.24 mm, B=1.07 mm, c=0.45 mm, C=0.44 mm, d=0.36 mm, D=0.17 mm, and E=1.07 mm. 
     A bag was manufactured by a general three-way bag making machine using a two-layer laminated film that includes a 15 μm biaxial stretched nylon film (G-100 manufactured by Idemitsu Unitech Corporation) and a 50 μm straight-chain low-density polyethylene film (LS-711C manufactured by Idemitsu Unitech Corporation) and also using the zipper tape described above. Thus, a zipper-tape-equipped bag was manufactured. 
     Comparative Example 1 
     A zipper-tape-equipped bag was manufactured in similar fashion to Example 1 except that biting portions shown in  FIGS. 8 and 9  were manufactured as biting portions. 
     The dimensions of parts of the biting portions were as follows: b=1.24 mm, B=1.07 mm, c=0.77 mm, C=0.78 mm, d=0.36 mm, D=0.30 mm, and E=1.07 mm. 
     Comparative Example 2 
     A zipper-tape-equipped bag was manufactured in similar fashion to Example 1 except that biting portions shown in  FIGS. 10 and 11  were manufactured as biting portions. 
     The dimensions of parts of the biting portions were as follows: A=0.34 mm, b=0.72 mm, B=0.87 mm, c=0.58 mm, C=0.57 mm, d=0.22 mm, D=0.33 mm, and E=1.07 mm. 
     Evaluation Example 1 
     The zipper-tape-equipped bags manufactured in Example 1, and Comparative examples 1 and 2 were evaluated as below. The results are shown in Table 1. 
     [Evaluation Method] 
     (1) Sealing Performance after Opening/Closing 
     After the zippers were opened and closed ten times in succession, a pinhole checker (manufactured by Mitsubishi Gas Chemical Corporation) was enclosed in the bags to find out whether there is any leakage from the zippers. 
     (2) Sealing Performance after the Zippers were Kept Open 
     After the zippers were kept open up to half the width of the bags for 24 hours, the zippers were again fitted, and the pinhole checker was enclosed in the bags to find out whether there is any leakage from the zippers. 
     [Evaluation Criteria] 
     ◯: No leakage after 24 hours 
     Δ: Leakage found after 24 hours 
     x: Leakage found after one hour 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Evaluation results 
                   
               
            
           
           
               
               
               
               
            
               
                   
                 After opening/ 
                 After zippers 
                 Comprehensive 
               
               
                   
                 closing 
                 were kept open 
                 evaluation 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                 Example 1 
                 ∘ 
                 ∘ 
                 ∘ 
               
               
                 Comparative 
                 ∘ 
                 x 
                 x 
               
               
                 example 1 
               
               
                 Comparative 
                 Δ 
                 x 
                 x 
               
               
                 example 2 
               
               
                   
               
            
           
         
       
     
     INDUSTRIAL APPLICABILITY 
     A zipper tape and a zipper-tape-equipped bag according to the present invention are used for a bag to pack, for example, food, clothing or bedding in a sealed condition. 
     While several embodiments and/or examples of the present invention have been described above in detail, it will readily occur to a person skilled in the art that modifications may be made to the exemplary embodiments and/or examples substantially without departing from the novel teachings and advantages of the present invention. Accordingly, such modifications fall within the scope of the present invention. 
     The entire disclosures of the documents described in this specification are incorporated herein by reference.