Patent Publication Number: US-2010122436-A1

Title: Closure and band of connected closures

Description:
TECHNICAL FIELD 
     The present invention relates to a closure for closing and binding the neck of a bag containing food, agricultural products or the like, and to a band of connected closures that are connected directly to one another. 
     BACKGROUND ART 
     Conventional closures are disclosed for example in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4 and Patent Document 5. 
     These conventional closures are generally formed from plastic resin. For example, Patent Document 4 discloses a sheet consisting of an elastic synthetic resin material such as polypropylene, polyethylene, polyvinyl chloride, nylon or the like (see Patent Document 4, paragraph [0006]). 
     When such a closure has connection parts, fragments may break off when the closure is detached, and may cause contamination. This can also cause burr, which has been known to damage the hands. 
     The material used in the present invention is thick paper or paperboard, which is gentler on the hands of the user (consumer), and which may also reduce environmental load when the paper is made of plant material. Using thick paper also allows for the use of recycled pulp. It is also possible to inhibit the occurrence of fragments when a band of connected closures is cut apart. 
     Continuous closing machines are generally used for the actual closing, and the closures used in this case are in the form of a band of connected closures connected in a line. 
     Such a band of connected closures connected in a line is rolled and loaded into a compartment in the closing machine, and the closures are fed one by one from the compartment during closing. The closures being fed from the machine are detached at roughly the same time as they are clipped around an object to be closed. 
     That is, in the case of closing using an existing continuous closing machine, the connection parts need to be strong enough that they do not break even if pull force is applied in the feed direction of the closures, but must also be easy to detach when closing an object to be closed. 
     Patent Document 1: Japanese Patent Application Laid-open No. 2001-80654 
     Patent Document 2: Japanese Patent Application Laid-open No. 2000-179510 
     Patent Document 3: Japanese Patent Application Laid-open No. 2001-2092 
     Patent Document 4: Japanese Patent Application Laid-open No. H10-59334
 
Patent Document 5: Japanese Patent Application Laid-open No. S57-96954
 
     DISCLOSURE OF THE INVENTION 
     Problems that the Invention is to Solve 
     It is an object of the present invention to provide a closure which is gentle on the hands of the user (consumer), and which can be easily reused. 
     Another object is to provide a closure that is made moisture-resistant by lamination of synthetic resin and/or biodegradable resin, giving it excellent storability and machine operability in a continuous closing machine. 
     Another object is to provide a closure whereby occurrence of paper dust can be suppressed by laminating a synthetic resin and/or biodegradable resin. 
     Still another object is to provide a closure that has a smaller environmental impact than conventional closures. 
     Means for Solving the Problems 
     (1) The present invention is a closure having a closing function and reclosability, which is formed of a single paper layer or a composite layer having at least a layer formed of paper, and which has a closure hole, provided substantially in a center part, for closing an object to be closed, and which is further formed with, at one end, an opening smaller than the closure hole, the opening communicating with the closure hole. 
     The raw material of the layer of paper that forms the principal layer of the present invention is plant fiber cellulose acetate or the like. Colorants; sizing agents, clay and other fillers can also be added thereto. 
     (2) The closure having a closing function and reclosability according to (1) above, having, on side faces of the closure, detachable connection parts that are connected to other closures adjacent thereto that are in a line with the closure, when the closure and the other closures are formed as a band of connected closures. 
     (3) The closure according to (1) or (2) above, wherein the closure is formed of a composite layer having at least a layer formed of paper, and wherein at least one of layer or layers other than the paper layer is formed from synthetic resin and/or biodegradable resin. 
     Synthetic resin here means a synthetic polymer substance such as a thermoplastic resin or thermosetting resin. Examples include polyvinyl chloride, polystyrene, polypropylene, polyethylene, methacrylic resin, polycarbonate, polyamide, phenol resin, unsaturated polyester resin; alkyd resin, epoxy resin and the like. 
     A biodegradable resin is a resin containing mainly biodegradable materials, which decompose by the action of microorganisms. 
     Examples of raw materials that are biodegradable include biodegradable resins having plant-derived components and biodegradable resins having petroleum-derived components. A mixture of a biodegradable resin having plant-derived components with a biodegradable resin having petroleum-derived components may also be used. 
     Examples of plant-derived components include polylactic acid, polycaprolactam, polyvinyl alcohol, casein, glycerin fatty acid esters, soft polylactic acid compounds compounded from polylactic acid and palm oil containing glycerin fatty acid esters, polylactic acid/diol-dicarboxylic acid copolymer, starch-polyester resin and the like. 
     Starch-polyester resin does not undergo blocking when molded and worked into a film, and also has a blocking-prevention effect when blended with other resins, as well as having good welding properties, printing properties and durability. 
     Examples of petroleum-derived components include PET (polyethylene terephthalate) and a polybutylene adipate/terephthalate copolymer resin which is an aliphatic-aromatic copolyester resin having a structure based on module units consisting of terephthalic acid/butanediol adipic acid. 
     In particular, a closure with low environmental impact can be provided by means of a composite layer that combines a paper layer with a layer mainly made of a biodegradable resin. 
     (4) The closure according to (3) above, wherein the layer formed from the synthetic resin and/or biodegradable resin includes an oriented film. 
     Examples of the oriented film here include uniaxially oriented films and biaxially oriented films. This is a polyethylene or other polymer material that has been physically stretched in order to improve the strength and heat resistance of the film. Uniaxially oriented films have the property of being difficult to stretch in either the vertical or horizontal direction. Biaxially oriented films are materials that are difficult to stretch both vertically or horizontally. 
     (5) The closure according to (3) or (4) above, wherein the closure is formed of a composite layer comprising layers made of paper that are laminated on both surfaces of the layer of synthetic resin and/or biodegradable resin. 
     The resin layer here may be a single layer or a composite of two or more layers. 
     (6) The closure according to (3) or (4) above, wherein the closure is formed of a composite layer comprising the layers of synthetic resin and/or biodegradable resin laminated on both sides of the layer of paper. 
     The layers of synthetic resin and/or biodegradable resin in this case may be each a single layer or a composite of two or more layers. 
     (7) The closure according to any one of (3) to (6) above, wherein the layer of synthetic resin and/or biodegradable resin is formed from any one of olefin resin, polyethylene terephthalate (PET), polystyrene (PS), acrylonitrile (AN) and PVA (polyvinyl alcohol). 
     (8) The closure according to any one of (1) to (7) above, wherein one or more notches are formed in the connection parts of the closure from one or both surfaces thereof towards an inner layer. 
     (9) The closure according to any one of (3) to (8) above, wherein only the layer made of paper in the connection parts of the closure is severed. 
     By severing the layer of paper and forming the connection part only from those layers consisting of synthetic resin and/or biodegradable resin, it is possible to provide a closure with reduced detachment strength, and to inhibit the occurrence of paper dust. 
     (10) The closure according to any one of (1) to (9) above, wherein the weight per unit area of the paper (hereunder, also called the “basis weight”) is 400 to 1000 g/m 2 . 
     If the weight per unit area of the paper is less than 400 g/m 2 , it will not be strong enough to function properly as a closure, while if the weight exceeds 1000 g/m 2  the narrow opening will be difficult to open, and may not be sufficiently reclosable. 
     (11) The closure according to any one of (1) to (9) above, wherein the average length of fibers making up the paper is 1.0 mm to 4.0 mm. 
     If the average of the fiber lengths making up the paper is less than 1.0 mm, it will not maintain sufficient stiffness to function as a closure, while if the fiber lengths exceed 4.0 mm, the connection part will be difficult to sever. 
     (12) The closure according to any one of (1) to (11) above, wherein ink or a coating material is printed or coated on the surface of the closure. 
     (13) A band of connected closures formed by connecting the closures according to any one of (2) to (12) above in a line by means of the adjacent connection parts of the closures. 
     (14) A package product wherein the object is closed using the closure according to any one of (1) to (12) above. 
     EFFECTS OF THE INVENTION 
     By adopting the constitution of the present invention it is possible to provide a closure having a closing function and reclosability that is easy for users and reusable. 
     Moreover, the effect of providing a closure that is resistant to the influences of humidity changes while having excellent machine operability in a continuous closing machine is achieved by laminating a synthetic resin and/or biodegradable resin. 
     Furthermore, the effect of suppressing the occurrence of paper dust is also achieved by laminating a synthetic resin and/or biodegradable resin. 
     Another effect is to provide a closure that has less of an environmental impact than conventional closures. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     One example of an embodiment of the closure of the present invention is given below. The embodiment shown below is an example of the present invention, and the present invention is not limited to the embodiment described below. 
       FIG. 1  is a plane view showing a closure of an embodiment according to the present invention.  FIG. 1  only illustrates an embodiment of a closure of the present invention, and the form of the present invention is not limited thereby. 
     The closure  1  of this embodiment is formed of a composite layer having one layer of thick paper. As shown in  FIG. 1 , the closure  1  of this embodiment has closure hole  2 , roughly in the center of the plane view, for closing a bag or other object to be closed. An opening  3 , which communicates with and is smaller than closure hole  2 , is formed at one end of the closure. The closure also has detachable connection parts  4 ,  4  . . . on the side faces, which connect the closure in a line to other adjacent closures when the closure and the other closures are connected as a band of connected closures. 
       FIG. 2  shows cross-sections along line II-II in  FIG. 1  illustrating the layered structure of the closure  1  of this embodiment. The layered structures shown here are illustrative, and the layered structure of the present invention is not limited thereby. 
     The closure  1  shown in  FIG. 2(   a ) has a three-layer structure comprising paper ( 11 ), synthetic resin ( 12 ) and paper ( 13 ) in that order from the top. The synthetic resin here is preferably polyethylene terephthalate or polyethylene. The closure  1  shown in  FIG. 2(   b ) has a three-layer structure comprising synthetic resin ( 14 ), paper ( 15 ) and synthetic resin ( 16 ) from top to bottom. The closure  1  shown in  FIG. 2(   c ) has a five-layer structure comprising polyethylene terephthalate ( 17 ), polyethylene ( 18 ), paper ( 19 ), polyethylene ( 20 ) and polyethylene terephthalate ( 21 ) from top to bottom. The closure  1  shown in  FIG. 2(   d ) has a four-layer structure comprising polyethylene terephthalate ( 22 ), polyethylene ( 23 ), paper ( 24 ) and polyethylene terephthalate ( 25 ) from top to bottom. The closure  1  shown in  FIG. 2(   e ) has a two-layer structure comprising polyethylene terephthalate ( 26 ) and paper ( 27 ) from top to bottom. The closure  1  shown in  FIG. 2(   f ) has a three-layer structure comprising polyethylene terephthalate ( 28 ), polyethylene ( 29 ) and paper ( 30 ) from top to bottom.  FIG. 2(   g ) is a cross-section of a closure with a single-layered structure of paper ( 30 ). 
     In this case, the paper material and synthetic resin material can be layered together by melting and solidifying the synthetic resin material on the surface of the paper material, or by first preparing the paper material and synthetic resin material separately and then sticking them together with an adhesive. 
       FIG. 3  is a plane view showing one example of a band of connected closures of an embodiment of the present invention. 
     In the band  36  of connected closures shown in  FIG. 3 , closures formed of a composite layer having one layer of thick paper are attached together. 
     Closure holes for closing a bag or other object to be closed are provided roughly in the center of closures,  31 ,  31  . . . of this embodiment in the plane view. An opening smaller than the closure hole and communicating with the closure hole is formed at one end of the closure. Each closure also has detachable connection parts  34 ,  34  . . . on the side faces for connecting the closure to other adjacent closures in a line when they are connected in a band of connected closures. 
     A band  36  of connected closures of this embodiment is formed with the aforementioned connection parts  34 ,  34  formed on the side faces of closures  31  connected to each other in a line. Notches  35 ,  35  . . . are formed extending towards the inner layer on the surfaces of the connection parts of each closure. 
     An example of the band of connected closures of the present invention is given below. However, the present invention is not limited by this example. 
     Example 1 
     For the comparative example, nine pieces of grey-colored paperboard (MARICOAT made by Hokuetsu Paper Mills, Ltd.) were prepared as closure samples (single-layer samples). 
     Next, closure samples (composite layer) were prepared with the five-layer structure shown in  FIG. 2(   c ) and they had a laminated structure of PET/PE/grey-colored paperboard (paper)/PE/PET. The paper and PE were bonded by melting the polyethylene. The PE and PET (biaxial orientation) were laminated using an ether adhesive. 
     The polyethylene terephthalate layer was 12 μm thick and the polyethylene layer was 60 μm thick. 
     The aforementioned closure samples were each cut into strips 2 mm wide by 100 mm long, which were modified under the following conditions. 
     (1) Samples left to dry for 12 hours or more in a thermostatic oven at 50° C. (humidity 20%): storage under dry conditions 
     (2) Samples left for 12 hours or more at room temperature (humidity 55 to 65%): storage under normal humidity conditions 
     (3) Samples immersed in water and left for 12 hours in a container maintained at high humidity (humidity 85%) or more: storage under moist conditions 
     Sets of three samples for the respective types of samples (single-layer samples and composite layer samples) were each kept under each of the above three types of conditions, and removed. One sample from each set was selected, and bending stress was applied by folding once the sample at a 90° angle to one surface of the sample (hereunder, “single fold”). Another sample was then selected, and bending stress was applied by first folding the sample at a 90° angle to one surface and then folding it at a 90° angle to the other surface for a total of two folds (hereunder, “double fold”). Samples applied with no stress are referred to as “no fold”. 
     Both ends of each sample were held with chucks so that the longitudinal direction of the strip-shaped sample is aligned up and down, and tensile tests were performed by moving the movable chuck upwards. The evaluation results are shown in Table 1 below. 
     [Measurement Conditions] 
     Measurement equipment: Tensile tester (Orientec Corp. TENSILON RTC-1210A) 
     Sample width: 2 mm 
     Chuck movement speed: 300 mm/min 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Storage conditions 
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Normal 
                   
               
               
                   
                 Dry 
                 humidity 
                 Moist 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 No fold 
                 Single-layer samples 
                 15.4 
                 15.4 
                 13.0 
               
               
                   
                   
                 Composite layer 
                 30.5 
                 27.1 
                 23.9 
               
               
                   
                   
                 samples 
               
               
                   
                 Single 
                 Single-layer samples 
                 12.0 
                 12.8 
                 10.3 
               
               
                   
                 fold 
                 Composite layer 
                 25.6 
                 25.9 
                 22.4 
               
               
                   
                   
                 samples 
               
               
                   
                 Double 
                 Single-layer samples 
                 6.1 
                 8.6 
                 10.4 
               
               
                   
                 fold 
                 Composite layer 
                 23.4 
                 24.2 
                 21.2 
               
               
                   
                   
                 samples 
               
               
                   
                   
               
               
                   
                 (Unit: N) 
               
            
           
         
       
     
     Table 2 below shows the evaluation results of Table 1 as percentages given the results for the “no fold” sample under each type of storage conditions as 100. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 Normal 
                   
               
               
                   
                 Dry 
                 humidity 
                 Moist 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 No fold 
                 Single-layer samples 
                 100 
                 100 
                 100 
               
               
                   
                   
                 Composite layer 
                 100 
                 100 
                 100 
               
               
                   
                   
                 samples 
               
               
                   
                 Single 
                 Single-layer samples 
                 78 
                 83 
                 79 
               
               
                   
                 fold 
                 Composite layer 
                 84 
                 96 
                 94 
               
               
                   
                   
                 samples 
               
               
                   
                 Double 
                 Single-layer samples 
                 40 
                 56 
                 80 
               
               
                   
                 fold 
                 Composite layer 
                 77 
                 89 
                 89 
               
               
                   
                   
                 samples 
               
               
                   
                   
               
               
                   
                 (Unit: %) 
               
            
           
         
       
     
     Ordinarily, paper has the property of becoming hard and fragile when left under dry conditions. Under moist conditions, it becomes soft. That is, under dry conditions it becomes strong with respect to tension but weak with respect to bending. Under moist conditions, on the other hand, it becomes weak with respect to tension but resists crease formation when folded, with little change in breakability. 
     It can be seen from the evaluation results of Table 1 and Table 2 above that the samples left under the dry, normal humidity or moist conditions all undergo a decrease in tensile strength when subjected to bending stress. It is also shown that the decrease is greater with a double fold than with a single fold. 
     Looking at the “moist, double fold” samples for example, there was roughly 20% deterioration in the case of the paper single-layer sample, but less deterioration (about 11%) in the case of the composite layer sample. Looking at the “dry, double fold” samples, there was about 60% deterioration in the case of the single-layer sample, but only about 23% in the case of the composite layer samples, indicating good effects under dry conditions. 
     From this it can be seen that a composite layer closure sample is more resistant to bending stress than a paper single-layer sample due to the layering of a highly flexible synthetic resin. Because the synthetic resin is also resistant to the influences of moisture, moreover, a composite layer closure sample is also much stronger than a single-layer closure sample. 
     Example 2 
     The same grey-colored paperboard (MARICOAT made by Hokuetsu Paper Mills, Ltd.) used in Example 1 was prepared. 
     60 μm-thick polyethylene resin was then prepared. 
     A composite layer consisting of 12 μm polyethylene terephthalate resin bonded to 60 μm polyethylene resin was also prepared. 
     Using these three kinds of samples, the pulled distance and tensile strength of the test samples were measured using the tensile tester of Example 1. 
       FIG. 4  is a graph showing the relationship between pulled distance and tensile strength of a single-layer sample (paper). 
       FIG. 5  is a graph showing the relationship between pulled distance and tensile strength of polyethylene resin. 
       FIG. 6  is a graph showing the relationship between pulled distance and tensile strength of a composite layer. 
       FIG. 7  is a graph showing the relationship between pulled distance and tensile strength of a composite layer of paper and polyethylene synthetic resin. 
       FIG. 8  is a graph showing the relationship between pulled distance and tensile strength of a composite layer of paper and synthetic resin. 
     As shown in  FIG. 4 , the single-layer sample exhibited maximum strength when pulled about 1 mm. It is thought that this was the point at which the sample tore. 
     As shown in  FIGS. 5 and 6 , a synthetic resin layer does not tear at about 1 mm in the same way as paper. Up to about 3 mm strength increases proportionally, after which the resin exhibits a stable strength value without tearing and then tears. The inclination angle of the curve and the displacement before tearing differ depending on the type of synthetic resin. 
       FIG. 7  shows results for 60 μm polyethylene resin laminated on both sides of paper, while  FIG. 8  shows results for a composite layer of 60 μm polyethylene resin and 12 μm polyethylene terephthalate resin laminated on both sides of paper. As shown in  FIG. 7 , the resulting graph is roughly what would result from combining the graphs for the single-layer samples of  FIGS. 4 and 5 . The graph obtained in  FIG. 8  is roughly what would result from combining the graphs of  FIGS. 4 and 6 . 
     Thus, it is possible to adjust the strength by changing the type of synthetic resin. Moreover, while the connection parts of the single-layer samples break when pulled about 1 mm, laminating a synthetic resin allows for stable transportation because breakage does not occur even when the connection parts are pulled with strong pull force. 
     The breaking strength of the connection parts can also be adjusted by adjusting the combination and thickness of the synthetic resin layers. 
     Example 3 
     Next, the amount of paper dust occurring when the paper is broken or cut was tested by visual observation. 
     350 μm-thick paper (basis weight 280 g/m 2 ) was prepared. 
     A composite layer was also prepared consisting of 60 μm-thick polyethylene resin (PE) attached to both sides of the aforementioned paper. 
     Each sample was cut into 30 mm width and 100 mm long strips, and a folding line was drawn across the width of each strip. Black sheets were prepared, and each strip was subjected several times to bending stress along the folding line atop the black sheet. Samples were torn along the fold line after five folds and after ten folds, and the amount of paper dust scattered on the black sheet was examined visually. 
     The results of observation are shown in Table 3. In the table, ◯ indicates no fallen fibers (paper dust), Δ indicates that fibers (paper dust) of less than 1 mm fell, and x indicates that fibers (paper dust) of 1 mm or more fell. 
     
       
         
           
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                 PE laminate on 
               
               
                 Times folded 
                 Paper only 
                 both sides 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 1 
                 ◯ 
                 ◯ 
               
               
                 5 
                 Δ 
                 ◯ 
               
               
                 10 
                 X 
                 Δ 
               
               
                   
               
            
           
         
       
     
     When bending stress is applied multiple times to the same site, the fibers at the folding site become loose. When this area is torn, paper dust is likely to occur. 
     As shown in Table 3 above, when the synthetic resin PE is laminated on both sides of paper, the fibers on the surface of the paper adhere to the polyethylene resin and are held by it even under repeated bending stress, resulting in very little paper dust. 
     Thus, it is possible by laminating synthetic resin on a layer formed from paper to prevent scattering of paper dust and suppress the problem of foreign matter contamination of the object to be closed. 
     Example 4 
     Two sheets (basis weight 600 g/m 2 ) of grey-colored paperboard (MARICOAT made by Hokuetsu Paper Mills, Ltd.) were prepared for each sample. 
     Closure samples were prepared with the layered structures shown in  FIGS. 9(   a ) to ( e ) using this grey-colored paperboard. The closure samples used in this example were bands of connected closures comprising multiple closures connected by their connection parts. 
     Sample 1: grey-colored paperboard ( 41 )/80 μm PE ( 42 )/grey-colored paperboard ( 41 ) 
     In the connection parts, the surface layers formed by paper on both sides are cut, leaving the closures attached by the synthetic resin layer ( FIG. 9(   a )). 
     Sample 2: grey-colored paperboard ( 41 )/40 μm PE ( 42 )/12 μm PET ( 43 )/40 μm PE ( 42 )/grey-colored paperboard ( 41 ) 
     In the connection parts, the surface layers formed by paper on both sides are cut, leaving the closures connected by the synthetic resin layers ( FIG. 9(   b )). 
     Sample 3: grey-colored paperboard ( 41 )/40 μm PE ( 42 )/12 μm PET ( 43 )/40 μm PE ( 42 )/grey-colored paperboard ( 41 ) 
     Notches are formed in the connection parts through about 2/3 of thickness of the surface of both surface layers formed from paper, leaving the closures connected by the synthetic resin layers and by thinned layer of paper ( FIG. 9(   c )). 
     Sample 4: grey-colored paperboard ( 41 )/40 μm PE ( 42 )/12 μm PET ( 43 )/40 μm PE ( 42 )/grey-colored paperboard ( 41 ) 
     In the connection parts, one of the surface layers formed of paper is cut, leaving the closures connected by a layer of synthetic resin and a single layer formed of paper ( FIG. 9(   d )). 
     Sample 5: grey-colored paperboard ( 41 )/40 μm PE ( 42 )/12 μm PET ( 43 )/40 μm PE ( 42 )/grey-colored paperboard ( 41 ) 
     No notches are formed in the connection parts ( FIG. 9(   e )). 
     A connection strength test was performed using the bands of connected closures described above. Connection strength was measured in two directions, i.e., in the direction of feed and in the direction of across-the-width. 
     Connection strength in the direction of feed was measured as shown in  FIG. 10  by securing closures  51  and  51  connected by connection parts  52  with chucks  55  and  56  disposed above and below the closures, exerting perpendicular pull, and measuring the strength at the time that the connection parts of the adjacent closures were detached. 
     Connection strength in the across-the-width direction was measured as shown in  FIG. 11  by securing closures  51  and  51  connected by connection parts  52  and  52  with chucks  55  and  56  disposed above and below the closures, exerting perpendicular pull, and measuring the strength at the time when the connection parts of the adjacent closures were detached. 
     The results are shown in Table 4. 
     
       
         
           
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                 Tensile strength in 
               
               
                 Sample 
                 Tensile strength in 
                 across-the-width 
               
               
                 No. 
                 direction of feed 
                 direction 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 1 
                 1.3 
                 1.2 
               
               
                 2 
                 4.8 
                 5.1 
               
               
                 3 
                 6.5 
                 7.3 
               
               
                 4 
                 9.7 
                 10.4 
               
               
                 5 
                 15.3 
                 16.2 
               
               
                   
               
               
                 (Unit: N) 
               
            
           
         
       
     
     As shown in Table 4 above, Sample No. 4 having notches formed on the surface of one side of the connection parts on the band of connected closures had less detachment strength in both the direction of feed and the across-the-width direction than Sample No. 5, which had no formed notches. 
     It can also be seen that Sample No. 3 having notches formed about 2/3 of the way towards the inner layer on both surfaces had less detachment strength than Sample No. 4. Samples No. 1 and No. 2 whose paper layers are severed in the connection parts had even less detachment strength, and Sample No. 1 in particular had particularly low detachment strength in the across-the-width direction. 
     When an actual package product is closed with a closure, the idea is that a band of connected closures is reeled out along guard rail  58  in the direction of the arrow as shown in  FIG. 12 , and open ends  55  of package products  54  which are being transported in the direction of the arrow by conveyor belt  52  or the like are inserted into the openings communicating with the closure holes at the center of closures  51  as hammer  57  is moved from the side of the closure in the direction of the arrow to hit the closure and detach it from the band. 
     In such a case, it is desirable that not only the tensile strength in the direction of feed but also the tensile strength in the across-the-width direction be somewhat low. 
     Example 5 
     One example of closures according to the present invention was manufactured and subjected to impact-resistance testing (drop test). 
     The closures prepared and used in this example were single-layer paper samples 22 mm long and 21 mm wide, with a basis weight of 280 g/m 2  (Sample 6), 440 g/m 2  (Sample 7), 560 g/m 2  (Sample 8), 840 g/m 2  (Sample 9) and 1100 g/m 2  (Sample 10), and a commercial plastic closure (polystyrene, 800 μm thick, Sample 11) was also prepared. 
     The impact resistance test was performed as follows. 
     First, a one-loaf bread bag was inflated with air, and the opening was closed with the closure. 
     Next, the closed bread bag was placed on a smooth floor. A square weight was then dropped towards the top of the bag from the specific heights shown in Table 5 below, in such a way that the bottom face of the weight remained level. 
     The degree of damage to the closure from the shock of the falling weight was observed visually. The results are shown in Table 5. 
     In Table 5, ◯ means no damage to the closure, and x means the closure tore or was detached from the opening of the bag. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 5 
               
             
            
               
                   
                   
               
               
                   
                 Drop height (mm) 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Sample 
                 30 
                 50 
                 100 
                 300 
                 600 
                 900 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 6 
                 X 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                 7 
                 ◯ 
                 ◯ 
                 X 
                 — 
                 — 
                 — 
               
               
                 8 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 X 
                 — 
               
               
                 9 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 X 
               
               
                 10 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
               
               
                 11 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 X 
                 — 
               
               
                   
               
            
           
         
       
     
     As shown above, in the case of Sample 6 with a basis weight of 280 g/m 2 , the closure was too soft and the binding strength insufficient. 
     Example 6 
     A bending strength test was performed using the closures prepared in Example 5. 
     The bending strength test was performed by the method shown in  FIG. 13  using a tensile tester (TENSILON RTC-1210A, made by Orientec Co.). 
     Using a closure shown in  FIG. 13(   a ), two strings  63  and  64  were tied to either side of opening  62  of closure  61  as shown in  FIG. 13(   b ), and secured to chucks  65  and  66  located above and below the closure. 
     In this state chucks  65  and  66  were moved up and down, respectively as shown in  FIG. 13(   c ), and the strength was measured when the opening reached 10 mm. The results are shown in Table 6. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 6 
               
               
                   
                   
               
               
                   
                 Sample No. 
                 Strength 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 6 
                 0.1 
               
               
                   
                 7 
                 0.7 
               
               
                   
                 8 
                 0.75 
               
               
                   
                 9 
                 2.0 
               
               
                   
                 10 
                 2.4 
               
               
                   
                 11 
                 1.25 
               
               
                   
                   
               
               
                   
                 (Unit: N) 
               
            
           
         
       
     
     It appears from looking at the results of Table 6 that Sample 6 with a basis weight of 280 g/m 2  could detach because it would not be able to withstand the rigidity of the bag. On the other hand, Sample 10 with a basis weight over 1000 g/m 2  was rigid itself and thus the closure was difficult to clip around the opening of a bag by fingers. 
     It was confirmed from the results of Table 5 and Table 6 that paper with a basis weight of 440 g/m 2  to 840 g/m 2  can be preferably used. 
     Example 7 
     Closures were prepared using food packaging paper with relatively long fibers (100% virgin pulp, no recycled paper) and a basis weight of 350 g/m 2 , with connection parts on the sides, to prepare a band of connected closures in which the adjacent connection parts were connected to each other in a line (Sample 12). 
     A band of connected closures was also prepared using the grey-colored paperboard (MARICOAT made by Hokuetsu Paper Mills, Ltd.) with relatively short fibers and a basis weight of 600 g/m 2 . Each closure was provided with connection parts on the side faces that were connected in a line to adjacent connection parts to prepare a band of connected closures (Sample 13). 
     A connection strength test was performed using these bands of connected closures. 
     As shown in  FIG. 11 , closures  51  and  51  connected by connection parts  52  and  52  were secured with chucks  55  and  56  arranged above and below the closures, perpendicular pull was exerted, and the strength was measured at the time that the connection parts of the closures were detached. 
     The results are shown in Table 7. 
     
       
         
           
               
               
               
             
               
                 TABLE 7 
               
               
                   
               
               
                 Sample 
                 Measurement 
                 600 g/m 2   
               
               
                 No. 
                 value 
                 conversion 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 12 
                 8.0 
                 13.7 
               
               
                 13 
                 9.2 
                 9.2 
               
               
                   
               
               
                 (Unit: N) 
               
            
           
         
       
     
     As shown in Table 7 above, Sample 13 with relatively short fibers had less connection strength than Sample 12 with relatively long fibers. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plane view showing one example of a closure of an embodiment of the present invention. 
       FIG. 2  is a cross-section along an arrow II-II showing a closure  1  of the embodiment shown in  FIG. 1 . 
       FIG. 3  is a plane view showing part of a band of connected closures of another embodiment of the present invention. 
       FIG. 4  is a graph showing the relationship between pulled distance and tensile strength for a single-layer sample (paper). 
       FIG. 5  is a graph showing the relationship between pulled distance and tensile strength for polyethylene. 
       FIG. 6  is a graph showing the relationship between pulled distance and tensile strength for a composite layer. 
       FIG. 7  is a graph showing the relationship between pulled distance and tensile strength for a composite layer of paper and polyethylene synthetic resin. 
       FIG. 8  is a graph showing the relationship between pulled distance and tensile strength for a composite layer of paper and synthetic resin. 
       FIG. 9  shows cross-sections of the closures of Example 4, which consist of layers of paper and synthetic resin. 
       FIG. 10  is an outline explaining a connection strength test in the direction of feed performed using the band of connected closures of Example 4. 
       FIG. 11  is an outline explaining a tensile strength test in the across-the-width direction using the bands of connected closures according to Examples 4 and 7. 
       FIG. 12  is an outline showing one example of a method for closing an object to be closed using a closure according to an embodiment of the present invention. 
       FIG. 13  is an outline explaining the bending strength test performed in Example 6. 
     EXPLANATION OF REFERENCE NUMERALS 
     
         
         
           
               1 ,  31 ,  51 ,  61  Closure 
               2  Closure hole 
               3 ,  62  Opening 
               4 ,  34 ,  52  Connection part 
               11 ,  13 ,  15 ,  19 ,  24 ,  27 ,  30 ,  41  Paper layer 
               12 ,  14 ,  16 ,  17 ,  18 ,  20 ,  21 ,  22 ,  23 ,  25 ,  26 ,  28 , 
               29 ,  42 ,  43  Synthetic resin layer 
               35  Notch 
               36  Band of connected closures