JP2572499B2 - Manufacturing method for self-standing bags - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a self-supporting bag which is excellent in stability and shape retention when it is self-standing.

[0002]

2. Description of the Related Art Conventionally, a self-supporting bag made of plastic film has been known which can stand up without falling down when contents are put therein. These self-supporting bags include a body film called a doipack and a film constituting the bottom surface.
A double-folded and rounded (circular) seal, or a bottom film folded at the portion forming the bottom of two opposing body films so that they are angled and integrated so as to be integrated. (For example, Japanese Unexamined Patent Publication No. 57-46750) or a film having a bottom portion folded into a W-shape to have an angle and seal the side surfaces to form a bottom surface. Are made to be self-supporting so that they become square (for example, Japanese Patent Application Laid-Open No. 56-123255), or ones that have a gusset-folded portion to become the side wall surface of the bag to provide self-supporting (for example, 54-80
No. 72, JP-A-60-172656 and the like. Of these, the Doypack format is used to fill the liquid material as content and give it independence.
Or, those having a square bottom are usually used, and those obtained by gusset-folding the side wall have been mainly used in combination with a paper box, or have been mainly used for powdery materials. However, the conventional free-standing bag has the same width at the bottom and the top, and the rigidity is insufficient toward the top, so it cannot be said that the bag has excellent stability and shape retention. It was difficult to handle when discharging things.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the conventional self-standing bag, and is stable and self-supporting when contents, especially liquid materials or substances having fluidity, are charged. It is an object of the present invention to provide a method for producing a self-standing bag that can maintain the shape of the bag.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a film for manufacturing a self-standing bag composed of a long plastic film having a trunk component and a bottom component. When the bottom component is bent in a mountain fold in the longitudinal direction, the trunk component is overlapped with the bottom component so that the bottom component can be substantially W-shaped.
In the state where the bag is folded in the shape of a letter, it has an inclined portion where the width of the bag is continuously narrowed so that the width of the upper self-standing bag is 80% or less of the width of the self-standing bag at the bent portion, and It has been found that the above-mentioned object is achieved by applying a heat seal wire forming a bag side portion having a constricted portion at an intermediate portion of the height of the bag, and the present invention has been completed.

That is, according to the present invention, a body constituting a body portion of a self-standing bag made of a long plastic film is provided at both ends in the width direction of a bottom constituting portion constituting a bottom portion of a self-standing bag made of a long plastic film. A step of superposing the trunk component on the bottom component so that the bottom component of the self-standing bag manufacturing film having the component can be substantially W-shaped when the bottom component is bent in a mountain fold in the longitudinal direction ( 1),
The width of the top of the self-standing bag is reduced to 80% or less of the width of the self-standing bag at the bent portion. A step (2) of applying a heat seal wire having a continuously narrowed inclined portion and forming a bag side portion having a constricted portion at an intermediate portion of 30 to 80% of the height of the bag when self-standing. The present invention provides a method for producing a self-standing bag, comprising the steps of: (3) punching out the bag with a heat seal line.

Hereinafter, the present invention will be described in detail. In the method for manufacturing a self-standing bag according to the present invention, the body of the self-standing bag made of a long plastic film is formed at both ends in the width direction of the bottom constituting part constituting the bottom of the self-standing bag made of a long plastic film. The body component is superimposed on the bottom component so that the bottom component of the self-standing bag manufacturing film having each of the body components can be substantially W-shaped when it is bent in a mountain fold in the longitudinal direction. Step (1) is required. The self-standing bag manufacturing film used in the present invention is a film comprising a trunk component and a bottom component, and the self-standing bag production film is composed of separate plastic films of the film of the trunk component and the film of the bottom component. May be used, or they may be bonded together.
They may be stacked on one another, or they may be folded on a cylindrical plastic film and stacked on two sheets.

[0007] When the film for producing a self-supporting bag used in the present invention comprises one film, a method for preparing a film for producing a self-standing bag can be carried out by various methods. For example, when the long trunk component and the long bottom component are made of different plastic films, the width direction of the two long trunk components at both ends of the width method of the long bottom component is used. Or a method in which the ends of two long plastic films in the width direction are bonded to each other, and a portion near the bonded portion is used as a bottom component. When the self-standing bag manufacturing film is obtained by folding one plastic film and stacking the two films, the vicinity of the folded portion may be used as the bottom component, or the discontinuous ends may be connected to each other. A method of bonding to form a bottom component near the end, or bonding a bottom component composed of a long plastic film separately prepared to the widthwise end of a trunk component composed of a long plastic film. There are ways to do that. Also,
When the self-standing bag manufacturing film is obtained by folding a tubular plastic film and stacking the two films, the vicinity of the folded portion can be used as the bottom component. The bonding of the bottom component can be performed by various bonding methods.
Adhesion by heat sealing is preferred. The heat-sealing of the bottom component to the body component is performed by the step (2) of the present invention.
May be performed at the same time as the heat sealing. In the present invention, the term “heat seal” includes not only heat seal in a narrow sense but also welding by ultrasonic waves and adhesion by heating of an adhesive, but heat seal in a narrow sense is preferable.

As described above, a film for producing a self-standing bag can be prepared by various methods, but it is preferable that the bottom component and the body component are prepared from different plastic films. When the self-standing bag manufacturing film is prepared by bonding the widthwise ends of the long body component to the widthwise ends of the long bottom component at an appropriate width, the bonded portion becomes freestanding. When the bag is free standing, it can also serve as a reinforcement around the entire bottom that comes into contact with the floor, and the reinforcement can increase the rigidity of the bottom. Also, if the bottom component and the trunk component are prepared from separate plastic films,
Since the thickness and type of each plastic film can be changed, it is possible to respond variously according to required characteristics. The width of this bonded part is usually 2mm to 10mm
Is preferred. It should be noted that, even when another film is used as a film for producing a self-standing bag, it is preferable to provide the above-mentioned adhesive portion all around the bottom of the self-standing bag. The self-standing bag manufacturing film may have one long bottom component, or may have two long bottom components at both ends in the width direction of the long trunk component. Although good, it is preferable to have two, because two self-standing bags can be punched in the width direction, and a self-standing bag can be efficiently manufactured.

As the material of the plastic film, various plastics can be used. For example, polyethylene, polypropylene, polyvinyl chloride, polyurethane, polyester, polyamide such as nylon, polycarbonate, ethylene-vinyl acetate copolymer, ethylene -Acrylic acid copolymers, ionomers, etc., and these substances may be used alone or in combination of two or more. When the body part and the bottom part of the bag are composed of different plastic films, each plastic film may be of the same type of plastic or different plastics. This is preferable because the material easily adheres. Further, the plastic film may be a single layer or a multilayer structure having two or more layers.

As a multilayer plastic film having two or more layers, a laminated film of various plastic films such as the above-mentioned plastic film can be used, but a multilayer plastic film obtained by laminating plastic films having different melting points is preferable. When heat-sealing a multi-layer plastic film with a difference in melting point at a temperature slightly higher than the melting point of a plastic film with a lower melting point, do not heat seal even if the plastic films with a higher melting point are in contact with each other. There is an advantage that a portion in contact with the plastic film can be selectively heat-sealed. In this case,
One or more small holes are made in the heat-sealed part of the multilayer plastic film, and the low-melting point plastic film is melted, and the low-melting point plastic penetrates into the interface of the high-melting point plastic film from the hole to form the high-melting point plastic. It is possible to heat seal the films. By providing such holes at appropriate positions, the contact surfaces between the plastic films having a high melting point can be selectively heat-sealed. The melting point is not particularly limited, but preferably has a difference of 10 ° C. or more, particularly preferably has a difference of 20 ° C. or more, and more preferably has a difference of 30 ° C. or more.

Examples of the plastic film having a low melting point include polyolefin films such as polyethylene and polypropylene, and examples of the plastic film having a high melting point include engineering plastic films such as stretched nylon 6-6 and stretched polyethylene terephthalate. Can be Also, in order to impart a barrier property to the plastic film, an aluminum foil, a saponified copolymer of ethylene and vinyl acetate (EVAL), or a plastic film using a film such as vinylidene chloride is used for the intermediate layer. be able to. Also, a flexible laminated film in which a film of a material other than plastic such as aluminum or paper is laminated on a plastic film can be used. The thickness of the plastic film of the present invention is not particularly limited, but usually 10 μm to 1000 μm is used, preferably 30 μm to 500 μm, and particularly preferably 30 μm to 300 μm.

In the step (1) of the present invention, the bottom component is formed into a substantially W-shape when the bottom component of the film for producing a self-standing bag is bent in a mountain fold in the longitudinal direction. It is necessary to overlap the components. In this superposition, the superimposed state is almost W
It does not need to be in the shape of a letter, and it is only necessary that the bottom component be substantially W-shaped when it is bent in a mountain fold in the longitudinal direction.
That is, the trunk component may be folded and overlapped without bending the bottom component, or the trunk component may be overlapped with the bottom component bent. As described above, when the long trunk component is superimposed on the long bottom component, respectively, two separate long components are separated from a bent portion when the long bottom component is bent in the longitudinal direction. Are overlapped with the bottom component. In this case, when the bottom component and the trunk component are composed of different films, the bottom component and the trunk component may not be joined, but may be joined. If the bottom component and the body component are not joined in step (1), they may be joined by heat sealing or the like in a step after step (1).

The bottom component can be formed into various bottom shapes by performing various types of heat sealing in a state where the body components are overlapped with each other. It is preferable to apply a heat sealing portion obliquely from the bent portion when the bottom component is bent in the longitudinal direction toward the bottom end. The diagonal heat seal portion is formed from the bent portion toward the bottom end. The diagonal heat seal portion forms a substantially hexagonal bottom portion when the self-supporting portion stands. That is, the diagonal heat seal is performed so as to form four sides of a substantially hexagonal shape. The shape of the oblique heat seal portion is usually a straight line, but it is not necessarily required to be a straight line, and may be a curved line. The angle of the oblique heat seal portion may be determined by appropriately selecting various angles, but is preferably in the range of 30 to 60 degrees. The oblique heat sealing portion may be performed without bending the bottom component, or may be performed by bending the bottom component.

In the present invention, the width of the upper part of the self-standing bag is 8 times larger than the width of the self-standing bag in the bent part when the bottom component is overlapped in a W-shape.
A heat having a slope portion where the bag width is continuously narrowed so as to be 0% or less, and forming a bag side portion having a vertical middle portion or a constricted portion at the upper portion thereof when the bag is self-standing. A step (2) of applying a seal wire is required. In order to form the self-standing bag of the present invention, it is necessary to bond the sides of the bag by heat sealing, and the heat sealing wire is formed in the above-described shape. That is, the side part shape of the self-standing bag can be formed by applying the heat seal line in a state where the bottom constituent parts made of a long plastic film are overlapped in a W shape.

[0015] The shape of the heat seal wire must have an inclined portion where the width of the bag is continuously narrowed so that the width of the upper part of the self-standing bag is 80% or less of the width of the self-standing bag at the bent portion. It is. Here, the width of the bag is the length between the inner ends of the two heat-sealing lines forming the sides of the self-standing bag when the self-standing bag is folded flat, and is parallel to the bottom end. Means the length in the direction. The slope portion where the width of the bag is continuously narrowed may be the entire heat seal line constituting the side portion of the bag, or may be a part of the heat seal line instead of the entire heat seal line. It is preferably at a portion above 30% of the height of the object, and more preferably at an upper portion of at least 40%. It is preferable that the width of the bag is substantially the same from the bottom of the bag to the height at which the inclined portion starts, but the bag may have an inclined portion where the width of the bag is enlarged. And the width of the upper part of the bag is 80% of the width of the bent part.
Must be less than or equal to 70%,
In particular, it is preferably at most 60%. Further, when there is a mouth at the upper end of the self-standing bag, the width of the upper portion of the bag is particularly preferably 60 to 20%.

The term “continuous” has not only a continuous meaning in a narrow sense but also an intermittent meaning, but continuous in a narrow sense is preferable. Further, the inclined portion may have a linear shape, a substantially linear shape, a polygonal line shape, a curved shape, or a combination thereof. The width of the heat seal line is usually selected in the range of 2 mm to 10 mm in order to have rigidity, but is preferably 3 to 7 mm. The rigidity of the self-standing bag can be increased by providing an inclined portion in which the width of the bag is continuously narrowed. In addition,
The mouth of the self-standing bag does not necessarily need to be provided at the upper end of the self-standing bag, and may be provided at the side wall of the self-standing bag, but is preferably provided at the upper end of the self-standing bag. The mouth of the self-standing bag can be sealed by attaching a stopper with a cap.

The heat seal wire constituting the side portion of the self-standing bag of the present invention needs to have a constricted portion at an intermediate portion of the height of the self-standing bag. The constricted portion in the present invention is a constricted portion that can be cut into the inside of the bag when the self-standing bag is filled with the contents to form a concave portion, and the width of the bag in the constricted portion is the upper and lower sides of the constricted portion. A heat seal line portion which is shorter than the width of the bag in at least one of the heat seal line portions connected to the heat seal line portion, and wherein the inner end of the heat seal line of the constricted portion is connected above and below the constricted portion. A line that is shifted to the inside of the bag rather than a straight line connecting the inside ends of the line portions. The magnitude of this deviation refers to the length between the straight line and the inner end of the heat seal line portion in the direction perpendicular to the straight line, but is not particularly limited, and is usually in the range of 1 mm to 20 mm, Preferably 1 mm to 10
mm range. At least one constricted portion may be provided for each heat seal wire, but two or more constricted portions may be provided. In addition, it is preferable to provide both heat seal wires symmetrically.

The position where the constricted portion is provided is an intermediate portion of the height of the self-standing bag. Here, the middle part is 30 heights of the self-standing bag.
% To 80%, preferably 40% to 70%, particularly preferably 40% to 60%. Further, the constricted portion is preferably provided at a position where the inclined portion starts, but may be provided at other positions. The shape of the constricted portion is not particularly limited, and may be various shapes such as a shape obtained by bending a straight line, a curved shape such as an arc, and the like, and a V shape is preferable as shown in FIG. This constricted portion can form a concave portion when the content is filled in the bag, because the constricted portion bites into the inside of the bag. By providing the constricted portion, the rigidity of the self-standing bag can be further increased, the shape retention of the self-standing bag can be improved, and the self-standing bag can be easily held by holding the constricted portion by hand. it can.

In the present invention, it is necessary to provide a step (3) of punching the self-standing bag with the heat seal line. Punching may be performed with a cutting blade or with a fusing blade. It is efficient and preferable to perform the punching at a time for the entire shape of the bag. In addition, it is preferable to perform the punching so as to take two self-standing bags in the width direction of the two long plastic films forming the body constituting portion. In other words, when using a self-standing bag manufacturing film in which both ends in the width direction of two superposed long plastic films are the bottom components of the self-standing bag, the two self-standing bags are opposed to each other. The shape can be punched.
The height and width of the self-supporting bag of the present invention are not particularly limited, and various sizes can be selected according to required characteristics. Excellent in nature.

The above steps (1) and (2) may be performed simultaneously or sequentially. Further, the steps (2) and (3) may be performed simultaneously or sequentially. In particular, when the method for producing a self-standing bag of the present invention is performed using a multilayer film of a plastic film having a different melting point, the heat seal required for forming the bag is as follows.
Since it can be performed at once, a self-standing bag can be efficiently manufactured. Each step of the present invention may be performed in the same place, or each step may be performed in another place. When each step is performed in another place, each step can be performed by sequentially and intermittently or continuously feeding a long plastic film each time each step is completed. Heat sealing and punching in the present invention may be performed intermittently by a vertically moving heat seal bar and punching blade,
A heat seal bar and a punching blade may be attached to the surface of the rotating roll, and the roll may be continuously rotated to continuously perform heat sealing and punching. In the present invention, self-standing bags can be continuously and efficiently manufactured by sequentially repeating the above steps (1) to (3).

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings of embodiments. The present invention is not limited by these examples. FIG. 1 shows an embodiment of a self-standing bag according to the present invention, in which two long plastic films are overlapped on a body part composed of long plastic films, and a long plastic film is placed on both ends in the width direction of the body part. FIG. 2 is a cross-sectional view showing a state in which the bottom component of the self-standing bag is adhered with a heat seal line having a width of 5 mm. FIG. 2 is a plan view of the film for producing a self-standing bag in FIG. FIG. 3 is a cross-sectional view showing a state in which the bottom component of the self-standing bag manufacturing film of one embodiment of the present invention is folded in a W shape and overlapped, and two long body components are overlapped. . FIG. 4 is a plan view showing a state in which the two superposed plastic films of FIG. 3 are heat-sealed to form two self-standing bags in the width direction thereof. FIG. 5 is a plan view of a self-standing bag according to one embodiment of the present invention.

In FIG. 1, two long multilayer plastic films having the same width (constitution: multilayer film of 100 μm thick polypropylene film and 15 μm thick stretched nylon 6-6 film, thickness: 120 μm) The body constituting part 1 is overlapped, the both ends in the width direction are opened, and the bottom part composed of a long multilayer plastic film (constitution: the same multilayer film as the film of the body constituting part, thickness: 120 μm) at both ends. 2 were heat-sealed at 180 ° C. with the polypropylene layer as the heat-sealing surface using a heat-sealing bar, and joined by a heat-sealing wire 3 having a width of 5 mm. Since the heat seal wire 3 is arranged around the bottom when the self-standing bag is self-standing, the rigidity of the bottom of the self-standing bag can be increased.

In FIG. 2, the bottom component 2 is provided with heat seal wires 3 at both ends in the width direction, and the bottom component 2 is so formed that the bottom of the self-standing bag becomes substantially hexagonal. A heat seal line 4 at a 45 ° angle from the bent portion 5 (broken line) when bent in the longitudinal direction toward the bottom end is 180 ° C.
Is applied by a heat seal bar. Note that the oblique heat seal wire 4 does not have to be linear, and the heat seal wire 4 surrounded by the heat seal wire 4 and the heat seal wire 3 at the bottom is not required.
The outer portion of the square may be formed in a shape that can be heat-sealed. Thereby, the rigidity of the bottom can be further increased. Further, the heat seal wire 3 and the heat seal wire 4 may be heat sealed at the same time.

In FIG. 3, in the tubular self-standing bag manufacturing film composed of the trunk component 1 with the bottom component 2 shown in FIG.
All the body parts 1 are superimposed from one end to the other to form a plane. The length between the bent portion 5 and the bottom end may be appropriately selected according to the required characteristics of the self-standing bag, but is preferably 10 to 40% of the width of the self-standing bag.

In FIG. 4, a vertical heat-seal bar at 180.degree. C. is pressed against the planar body component 1 shown in FIG. 3 to form a heat-seal wire 6 forming a side portion of the self-standing bag. Since the stacked body components have a polypropylene film having a low melting point on the inside, they can be easily fused by a heat seal bar at 180 ° C. The heat-sealing line 6 has a width of 5 mm, has a constricted portion in the middle part in the vertical direction of the self-standing bag, and the width of the bag is continuously reduced from the constricted portion toward the upper part of the self-standing bag. . On the other hand, the bottom part folded in a W-shape is heat-sealed on the surface where the polypropylene films are in contact with each other, and the heat-sealing wire 6 is applied. The innermost layer is a stretched nylon 6-6 film having a high melting point. Since heat sealing cannot be performed with a heat seal bar at 180 ° C., a large number of small holes are formed at the position of the heat seal line 6 in the bottom part before heat sealing, and then heat sealing is performed. The polypropylene melted from the hole by heat sealing with a bar is impregnated into the interface between the stretched nylon 6-6 films and joined. In addition, the heat sealing wire on the surface where the stretched nylon 6-6 films are in contact with each other may not be continuously heat sealed.
In FIG. 4, when the heat seal wire 6 is applied, the heat seal wire 3 and the heat seal wire 4 can be applied simultaneously. The heat sealing wire 3 and the heat sealing 4 can be performed by pressing a heat sealing bar on the multilayer plastic film. In this case, the surface where the polypropylene films with low melting points are in contact with each other is
Heat-sealed but stretched nylon 6-6 with high melting point
Since the surfaces where the films are in contact with each other are not heat-sealed, the heat seals 3, 4, and 6 can be performed efficiently. A mouth is provided at the upper end of the self-standing bag, and the width of the mouth is about 50% of the width of the bent portion at the bottom.
The plastic film 1 provided with the heat seal wire 6
The self-standing bag can be manufactured by punching the outside of the heat seal wire 6 with a punching blade. The construction and punching of the heat seal wire 6 may be performed simultaneously. The remaining long multilayer plastic film from which the self-standing bag was punched was wound on a roll (not shown).

FIG. 5 shows a self-standing bag in which a cap with a cap is attached to a punched self-standing bag. The heat seal line 6 on the side of the self-standing bag has a constricted portion sandwiched between points B and C at an intermediate portion thereof. At point A of the constricted portion, the width of the bag is narrower than point C, and point A is shifted inside the bag from the straight line connecting point B and point C.
4 mm. Also, the portion of the oblique heat seal wire 4 is
The portion surrounded by the heat seal wire 4 and the bottom heat seal wire 3 is heat sealed leaving an oval and a circle, and the rigidity of the bottom is further enhanced. In addition, the size of the self-standing bag is 26 cm in height, the width of the self-standing bag is 14 cm at the bent part 5, the width of the mouth at the upper end of the self-standing bag is 8 cm, and Length between ends is 4
cm.

[0027]

According to the present invention, a self-standing bag excellent in self-standing stability and shape retention and easy to handle can be efficiently produced.

[0028]

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a film for manufacturing a self-standing bag according to an embodiment of the present invention, in which a body constituted by two long plastic films is overlapped, and a width direction of the body constituted; FIG. 4 is a cross-sectional view showing a state in which a bottom component made of a long plastic film is formed at both end portions of FIG.

[0029]

FIG. 2 is a plan view of the self-standing bag of FIG. 1 when viewed from the bottom.

[0030]

FIG. 3 is a view showing a state in which a bottom component for manufacturing a self-standing bag according to an embodiment of the present invention is folded in a W shape and overlapped, and two long body components are overlapped. FIG.

[0031]

FIG. 4 is a plan view showing a state where two superposed body components of FIG. 3 are heat-sealed to form two self-standing bags in the width direction thereof.

[0032]

FIG. 5 is a plan view of a self-standing bag according to an embodiment of the present invention.

[0033]

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body part 2 Bottom part 3 Heat seal line 4 Heat seal line 5 Bending part 6 Heat seal line 7 Constriction part 8 Cap 9 Plug

Claims (4)

(57) [Claims] 1. A body constituting part of a body of a self-standing bag made of a long plastic film is provided at both ends in a width direction of a bottom part constituting a bottom part of a self-standing bag made of a long plastic film. A step (1) of superimposing a body component on the bottom component so that the bottom component of the self-standing bag manufacturing film can be substantially W-shaped when it is bent in a mountain fold in the longitudinal direction. The width of the upper part of the self-standing bag relative to the width of the self-standing bag of the bent part is 80 to the self-standing bag manufacturing film in a state where the bottom constituent parts are overlapped in a substantially W shape.
% Heat seal forming a bag side portion having an inclined portion where the bag width is continuously narrowed so as to be less than or equal to 30%, and having a constricted portion at an intermediate portion of 30 to 80% of the height of the bag when self-standing. A method for producing a self-standing bag, comprising: a step (2) of applying a wire; and a step (3) of punching the bag with the heat seal wire. 2. The self-standing bag manufacturing film according to claim 1, wherein the widthwise ends of the elongated body component are prepared by heat sealing at both ends of the elongated bottom component in the widthwise direction. Production method. 3. The self-standing bag according to claim 1, wherein the film for producing a self-standing bag has bottom portions at both ends in the width direction of the long trunk portion, and two self-standing bags are punched in the width direction. Production method. 4. In the step (1), when the body constituting part is overlapped with the bottom constituting part, and the bottom constituting part is bent in the longitudinal direction so that the bottom part becomes self-supporting in a substantially hexagonal shape. 2. The method for producing a self-standing bag according to claim 1, wherein a heat sealing portion is provided obliquely from the bent portion toward the bottom end.