Method and machine for producing tape-sealed bags

Abstract: In an automatic filling and closing process for flexible package in which a film (18) is supplied while being longitudinally fused, and the respective steps of filling the longitudinally fused film (18) with the contents, laterally fusing the film (18) and cutting the laterally fused area are performed, a slit (5) or a hole (11) is intermittently formed in the supplied film (18) at a site from unwinding of the film (18) to the longitudinal fusing during interruption of the supply of the film (18) in the steps of lateral fusing and cutting, and an opening fusing tape (6) is placed over said slit (5) or hole (11) to weld around the circumference of said slit (5) or hole (11), thereby obtaining a tape-sealed bag easily openable in approximately parallel with the laterally fused area. According to the invention, the technique of opening the bag by means of the easily openable fusing tape (6) using the film (15) having a relatively low separation strength can be applied to the pillow type bag which can be efficiently produced by use of the automatic filling and closing machine for flexible package.

Description: FIELD OF THE INVENTION The present invention relates to a method for producing a pillow type bag sealed with a tape adhered to any portion of a surface of the bag, and easily openable by taking an end of the tape with fingers and pulling it, and to an automatically filling and closing machine for carrying out that method. BACKGROUND OF THE INVENTION In Japanese Unexamined Patent Publication No. 7-76354, the present inventor has proposed a bag in which both side portions of a film thermally fusible in both faces thereof are arranged close to each other and covered with a separation tape, which is fused with outer faces of both side portions of the film to form a cylindrical tube, and both end portions thereof are laterally fused. This bag can be easily opened by taking an end of the tape with fingers and pulling it. However, according to the above-mentioned technique, the resulting bag is longitudinally opened. Bags are preferably longitudinally opened in some cases, and preferably laterally opened in the other cases, depending on the contents thereof. When the lateral opening is preferred, the above-mentioned technique can not comply with it. In NL 83-011 28 A a tape-sealed bag is disclosed in which a hole sealed by means of a pressure sensitive adhesive is provided. Recently, automatic filling and closing machines for flexible package have prevailed. In particular, a film is supplied while being longitudinally fused, and the respective steps of filling the longitudinally fused film with the contents, laterally fusing the film and cutting the laterally fused area are performed in turn. There is one longitudinally fused area on the back of the resulting bag and no longitudinally fused area on a surface of the bag, both the upper and lower ends are laterally fused. This is a so-called pillow type bag, and has widely prevailed. If this pillow type bag can be opened at its upper portion in approximately parallel with the laterally fused area by pulling the tape, a bag having both the sealing performance and the opening easiness is obtained. However, it was difficult to produce such a bag even by the technique described in Japanese Unexamined Patent Publication No. 7-76354. From the US-A-4 420 080, a method for producing a re-sealable dispenser container is known. According to this document, a sheet is supplied from a role and guided to a punching machine for perforating or punching an opening into the sheets. Afterwards, a flap is removed from another sheet and disposed over the perforated line or the opening. Afterwards, the flap is fixed to the sheet at one end of the flap by a heat-sealer. Afterwards, a content is put on the sheet and the content is wrapped into the sheet. The longitudinal edges of the sheet are sealed by means of a further heat-sealer. Afterwards, the sheet is sealed in a transverse direction behind and in front of the content by means of a further heat sealer. Afterwards, the sheet is cut by a cutting machine. All the steps are carried out in a consecutively manner. Further, from the GB-A-1 030 642, a method for producing tetrahedral containers is known in which a carriage carrying a heater platen is moved in synchronism with the movement of a paper stock which is used for forming the container. Thus, no interruption for fusing a tape over a hole is provided. Moreover, for the contents, it is generally desirable to laterally open the sealed bag from one end thereof in the longitudinal direction in many cases. Accordingly, a bag has been desired which can be easily opened in parallel with a laterally fused area by pulling an opening fusing tape. SUMMARY OF THE INVENTION Such an object is solved by a method of claim 1 and a machine of claim 2. The present invention provides a method for producing a tape-sealed bag by an automatic filling and closing process for flexible package in which a film is supplied while being longitudinally fused, and the respective steps of filling the longitudinally fused film with the contents, laterally fusing the film and cutting the laterally fused area are performed, comprising intermittently forming a slit in the supplied film at a site from unwinding of the film to the longitudinal fusing during interruption of the supply of the film in the steps of lateral fusing and cutting, and placing an opening fusing tape over said slit or hole to weld around the circumference of said slit; and an easily openable tape-sealed bag produced by this method. That is to say, in a vertical type automatic filling and closing machine for flexible package used in the present invention, the bag forming speed is usually 40 to 45 bags/minute, and up to about 60 bags/minute, and the supply of the film is interrupted in the steps of lateral fusing and cutting. Utilizing this interruption, the slit is formed in the lateral direction of the film, and this opening portion is covered with the opening fusing tape to weld around the circumference thereof in the next interruption. The present inventor has confirmed that such processing can be performed for a short period of 1 second or less, thus completing the present invention. The film in which the slit is formed and with which the opening fusing tape covering the slit is fused is supplied as such to a usual automatic filling and closing machine for flexible package, thereby obtaining the tape-sealed bag of the present invention. The tape-sealed bag of the present invention is characterized by that the slit and the tape are provided in approximately parallel with the laterally fused area of the pillow type bag. Conventionally, a slit in parallel with a longitudinally fused area could be formed. In this case, however, a horizontal type automatic filling and closing machine for flexible package had to be used, resulting in poor efficiency. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1(a) is a plan view showing the surface of a sealed bag of the present invention; Fig. 1(b) is a plan view showing the back of the sealed bag of the present invention; Fig. 2 is a perspective view showing the sealed bag of Fig. 1 ; Fig. 3 is a plan view showing a bag in which a short slit is formed at a side portion thereof; Fig. 4 is cross sectional views showing a bag using an opening fusing tape containing an adhesive, wherein (a) shows the step of fusing the tape with a bag material, and (b) is a cross sectional view for illustrating a phenomenon that an adhesive layer is exposed when the tape is separated; Fig. 5 is a schematic view for illustrating a method for producing a sealed bag of the present invention; and DESCRIPTION OF THE PREFERRED EMBODIMENTS Base films used in the sealed bags of the present invention are films of various plastics such as polypropylene, polyesters, polyethylene and nylon, laminated products thereof and products thereof laminated with aluminum evaporation layers, paper or polyvinylidene chloride layers. These base films are provided on both sides thereof with heat fusible layers having a low melting point such as low-density polyethylene and ethylene-vinyl acetate copolymer layers. When the base films are films which are heat fusible themselves, such as polyethylene films and polypropylene films, they may be monolayer films having no heat fusible layers. The longitudinally fused area used in the present invention is a fused areas formed in a supplying direction of the film forming the bag, and the laterally fused area is a fused area formed in a direction crossing the supplying direction of the film forming the bag, independently of the ratio of lengths of the completed bag. The pillow type bag as used in the present invention is a bag produced with a vertical type automatic filling and closing machine for flexible package and having one longitudinally fused area 3 on the back 1 thereof, no longitudinally fused area 3 on the surface 2 thereof and laterally fused areas 4 at both the upper and lower ends thereof. Accordingly, bags fulfilling these conditions are all included in the scope of the present invention, and a gusset type bag having folds on both sides is also naturally included. In the present invention, an easily separable tape generally used for a cover material of a vessel for jelly and yoghurt so as to be openable by hand is employed as an opening fusing tape 6. The easily separable films are widely commercially available, and include, for example, VMX22RX manufactured by Mitsubishi Chemical Corporation, CMPS07C manufactured by Tosero Co. Ltd and TAF610C manufactured by Tosero Co. Ltd. The peal strength of the easily separable films is 100 g/15 mm to 1500 g/15 mm, and preferably 300 g/15 mm to 1000 g/15 mm, and the fused width thereof is generally 1 mm to 3 mm. The easily separable films are used by backing them with films of polyesters, nylon, polypropylene and the like, and cutting them to the tape form. They may be backed after cutting to the tape form. In the present invention, a slit 5 is formed in parallel with the laterally fused area 4 on the surface 2 of the bag. The slit 5 is not required to be accurately parallel, and may be slant to the laterally fused area. However, the parallel slit is generally easy to use. Although there is no limitation on its position, the upper or lower end is preferred, and a position close to the laterally fused area and not in contact therewith is preferred. The opening fusing tape 6 is placed on a bag material, covering this slit 5, to weld around the circumference of the slit with no clearance between the tape and the bag material. A tape-fused area 7 covering the slit is preferably in place in the surface of the bag. Further, the slit may be shortened so that only a part of the width of the surface of the bag opens, depending on the contents, fluid or solid. The opening fusing tape 6 is required to have a pick-up flap 8 not fused by a length which can be taken with fingers, outside the tape-fused area at at least one end thereof. At the end of pick-up flap 8, the opening fusing tape 6 is fused in a dot-like form, leaving the pick-up flap 8 not fused by a length which can be taken with fingers. In particular, it is preferred that the tape is fused in a dot-like form, leaving the pick-up flap 8 not fused by a length which can be taken with fingers, wherein the pick-up flap 8 is allowed to project from the surface of the bag and turned up to the back. In such a dot-like fused area 9, white dots remain after separation. Accordingly, even if a opened bag is placed so as to be confused with goods not opened with malicious intent, it can be immediately distinguished. Fig. 2 is a perspective view showing the sealed bag thus obtained. The slit 5 is not necessarily formed on the surface 2 of the bag, and may be formed short on a side portion 10 of the bag, namely a portion forming the boundary between the surface 2 and the back 1 where the film is folded, as shown in Fig. 3. The formation of the short slit 5 across the side portion 10 provides the advantage of easy handling when the bag contains the contents such as the solid, fluid or semifluid contents which are liable to be scattered about in taking out them at once. Further, two or more short slits can also be formed, making them cross or with ends thereof brought into contact with each other. Further, when adhesive force remains on a face of the opening fusing tape or a separation face of the bag after the bag is opened by pulling the tape, the opened bag can be sealed again, which is preferred from the viewpoint of keeping the airtightness of the contents after opening. In that case, as the opening fusing tape 6, a substrate layer 13 is laminated with an adhesive layer 14, a tearable layer 15 formed of a material which is torn in any directions by weak force and a heat fusible layer 16, as shown in Fig. 4. As the tearable layer 15, an aluminum foil, ordinary paper composed of staple fibers or a plastic film treated so as to be torn in all directions (for example, a film allowed to contain many bubbles) can be used. The slit is covered with this opening fusing tape 6, and the circumference around the slit is heat pressed with a heat sealer 17. As a result, a portion of the opening fusing tape corresponding to the heat sealer 17 is fused with the bag material (the surface 2 of the bag in Fig. 4(a)) to maintain the bag in the sealed state. When the opening fusing tape 6 is pulled at an end thereof, the adhesive layer 14 is separated because of strong heat fusion as shown in Fig. 4(b). The tearable layer 15 is approximately surely torn at an interfacial portion between a fused area and a non-fused area when the tape is separated. On the other hand, although the heat fusible layer 16 is not formed of a material torn only by pulling, it is laminated with the film layer such as the aluminum foil which is torn in all directions by weak force. Accordingly, the extendable characteristics disappear and the heat fusible layer is easily torn together with the tearable layer 15, resulting in exposure of the adhesive layer. Thus, the use of the opening fusing tape 6 containing the adhesive layer 14 permits the bag to be sealed again by its adhesive force after opening and the contents to be stored for a long period of time. Fig. 5 is a schematic view for illustrating a method for producing the sealed bag of the present invention. The reference numeral 18 designates a wound film, and 19 designates a winding core. The film unwound by a conventional method is supplied to an automatic filling and closing machine for flexible package. In the automatic filling and closing machine for flexible package, there are the steps of laterally fusing the film and cutting a central portion of the laterally fused area after termination of longitudinal fusion and filling. In these steps, the supply of the film is interrupted. At this moment, the slit 5 is formed in the film before it enters the automatic filling and closing machine for flexible package. That is to say, the slit 5 is formed before the unwound film is longitudinally fused. At the moment when the supply of the film is interrupted next, the tape is fused with the bag material. That is to say, the slit is covered with the opening fusing tape 6, which is fused with the bag material around the circumference of the opening portion. Then, using the conventional automatic filling and closing machine for flexible package, the pillow type bag can be efficiently produced by the conventional method. The technique of opening the bag by means of the easily openable fusing tape using the film having a relatively low separation strength can be applied to the pillow type bag which can be efficiently produced by use of the automatic filling and closing machine for flexible package. EXAMPLES Using a wound film 18 having a width of 340 mm in which both faces of a 15 µm thick nylon film were laminated with 40 µm thick linear low-density polyethylene films, a pillow type bag was produced with a conventional automatic filling and closing machine for flexible package, as shown in Fig. 5. In this embodiment, a slit 5 was formed in a direction crossing the film between unwinding of the film and winding thereof around a sailor of the automatic filling and closing machine for flexible package, as shown in Fig. 5. The slit was formed to a length of 132 mm in a central portion of the film. At the moment when the supply of the film is interrupted next, a opening fusing tape 6 was placed over the slit 5 to weld around the circumference of the slit 5. As the opening fusing tape 6, a 18 mm wide tape was used in which an inner face of a 16 µm thick polyester film was laminated with a 50 µm thick easily separable film. As the easily separable film, C M P S 0 1 7 C manufactured by Tosero Co. Ltd was used. Inner faces of both sides of the film were allowed to face each other and fused with each other (inner to inner) to form a cylindrical tube. The tube was filled with cookies as the contents supplied from a hopper, laterally fused and cut a central portion thereof. As a result, a sealed bag having the surface as shown in Fig. 1 was obtained. The sealed bag had a bag width of 160 mm, a bag length of 235 mm and a 15 mm wide laterally fused area. Further, when a 180 mm long opening fusing tape 6 was placed over the slit and fused, two dot-like fused areas 9 were each formed at upper ends of positions of 3 mm and 7 mm from both ends of the opening fusing tape 6. A bag produced therefrom was as shown on the left side of Fig. 1(b), and the opening fusing tape 6 was slightly out of the surface 2 of the bag. Two dot-like fused areas 9 were each formed at an upper end of a portion out of the surface. A lower portion of the dot-like fused areas 9 was left not fused to form a pick-up flap 8 which could first initiate to open the bag. When two dot-like fused areas 9 were vertically arranged as shown on the right side of Fig. 1(b), a pick-up flap 8 was formed on the left side of the dot-like fused areas 9. The fused portion of the opening fusing tape 6 turns white after separation, so that it can be distinguished at a glance that the tape is separated. As a result, when goods placed on show are opened and sealed again after insertion of poisonous substance with malicious intent, users can immediately distinguish them. This is therefore preferred in terms of the safety of goods.

Claims: A method for producing a tape-sealed bag by an automatic filling and closing process for flexible package in which a film (18) is supplied while being longitudinally fused, and the respective steps of filling the longitudinally fused film (18) with the contents, laterally fusing the film (18) and cutting the laterally fused area (4) are performed, comprising intermittently forming an opening in the supplied film (18) at a site from unwinding of the film (18) to the longitudinal fusing during an interruption of the supply of the film (18), and placing an opening fusing tape (6) over said opening and fusing it around the circumference of the opening during the next interruption of the supply of the film (18), characterized in that said steps of laterally fusing and cutting the film (18) are performed during one and the same interruption and at one and the same station when the opening is formed, and in that the steps of placing the opening fusing tape (6) and fusing it are performed during one and the same interruption, and at one and the same station and in that the opening is formed as a slit (5) in a direction crossing the direction of the film supply. Automatic filling and closing machine for carrying out the method of claim 1, comprising a winding core (19) for supplying the film (18), a sailor for longitudinally winding there around the film (18) supplied from the winding core (19) and for filling, a device for longitudinally fusing the film (18) parallel to its supplying direction, and a device for laterally fusing and a device for cutting the film (18) in a direction crossing the supplying direction while interrupting the supply of the film (18), a device, provided at a site between the winding core (19) and the device for longitudinally fusing the film (18), for forming the opening in the supplied film (18) during an interruption of the supply of the film (18) and a device, provided at a site between the winding core (19) and the device for longitudinally fusing the film (18), for placing and a device for fusing the opening fusing tape (6) having an easily separable tape inside around the circumference of said opening characterized in that said device for laterally fusing and said device for cutting the film (18) are integrated such that the laterally fusing and the cutting are performed during the interruption when the opening is formed, and in that said device for placing said opening fusing tape (6) over said opening and said device for fusing said opening fusing tape (6) are integrated such that the placing and fusing are performed during one and the same interruption, and in that said device for forming the opening is adapted to form a slit (5) in a direction crossing the direction of the film supply.

Inventors: TOSHIMA ISAO, TOSHIMA, ISAO
Applicants: HOSEKI PLANNING KK, SANWA AUTOMATIC MACHINERY CO L, KABUSHIKI KAISHA HOSEKI PLANNING, SANWA AUTOMATIC MACHINERY CO., LTD.
Application year: 1998
Main classification: B65B9
IPC codes: B65D75