JP2004091052A - Easily tearable packaging bag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging bag to which easily tearing property, that is, the easily tearing property is given without causing the wear or the like of a packaging material substantially, and furthermore, without lowering sealing strength and impact strength resistance at a sealing portion. <P>SOLUTION: THe easily tearable packaging bag is provided in which an outer superficial layer and/or an intermediate layer are formed by overlapping a laminated body comprising a thermo-plastic resin of molecular orientation, and a tear starting portion or its neighboring thermo-plastic resin is weakened. The weakened resin layer is made by forming a resin layer weakened by fusion distributed in a face direction continuously or discontinuously over a range larger than 1 mm in width in a direction crossing an opening direction, and by foaming the thermo-plastic resin in which the tear starting portion or its neighboring outer superficial resin layer and/or the intermediate resin layer are higher than 0.1 wt.% in a moisture content based on the JIS K 0068. <P>COPYRIGHT: (C)2004,JPO

Description

TECHNICAL FIELD The present invention relates to an easily tearable packaging bag, and more specifically, is formed by stacking a laminate made of a thermoplastic resin in which at least an outer surface layer and / or an intermediate layer is molecularly oriented to form a bag. The present invention relates to a packaging bag provided with easy tearing properties without substantially causing abrasion or the like of the packaging material, and further without reducing the sealing strength and impact resistance of the sealing portion.

2. Description of the Related Art In recent years, as a packaging bag for storing foods and other small products, a plastic bag or a laminated bag formed by laminating paper, metal foil, and the like has been widely used. There is an advantage that after filling, the product can be easily sealed by heat sealing, and also has excellent airtightness and bag breaking strength.

However, the plastic film has a problem that the tear strength is high, and it is often difficult to tear by hand when taking out the contents.

た め For this reason, packaging bags provided with hand tearability, so-called easily tearable packaging bags, have been used for a long time. The most typical example of the easily tearable packaging bag has a notch called a notch at the edge of the heat seal, and stress concentration occurs at the tip of the notch, and the laminate is opened by tearing. It is relatively easy to do.

However, in this type of easily tearable packaging bag, the sealing width of the notched portion is naturally reduced, and the strength of this portion of the bag cannot be reduced. In addition, it is necessary to make the seal width of the seal edge sufficiently large and to sufficiently secure the residual width of the seal portion in the notch forming portion, and therefore, there is a problem that the amount of the packaging material used increases. Another problem is that notch chips are generated along with the formation of the notch, and special removing means and monitoring means are required so that the notch chips do not enter the product.

As a solution to the above-mentioned disadvantages of the notched packaging bag, it is already known to form a weakened portion other than the notch in the opening start portion of the packaging bag or in the vicinity thereof. In a plastic sealed subdivided bag formed by fusing a three-sided, jointed palm and sealing both end edge seal portions, a large number of scars are substantially densely provided on an edge line at a fusion portion of a sheet constituting the bag. A sealed dispensing bag is described. It is also known to provide a large number of fine holes instead of the above-mentioned scars.

It is also known that instead of weakening the opening start portion, an opening line is formed by a laser or the like in a portion to be cut of a bag by a laser or the like. A method for forming an opening line in a liquid paper container, characterized in that a carbon dioxide laser is irradiated in a substantially horizontal direction from the surface layer side to the entire periphery near the upper end side to form an opening line composed of a thin groove having a width of about 1 mm. Have been.

Patent Document 3 below discloses a packaging bag having a heat-sealed portion at both ends, wherein each of the edges of a tear guiding groove formed at a position corresponding to each other on both the front and back surfaces of the packaging bag, It describes an easily tearable packaging bag located at a distance of about 1 mm or more from the side edge of the heat-sealed portion, and also describes that the guide groove is formed by a laser.

JP-B-61-39228 JP-A-62-222835 JP-A-4-327139

However, with the conventional means for forming the weakened portion at the opening start portion or the portion to be torn, it is often difficult to achieve a good balance between the strength of the packaging material and the easy tearability. That is, the characteristic required for the easily tearable packaging bag is to easily introduce a break for tearing, but a means for weakening the opening start portion with the above-mentioned blade or the like, or a means for forming a groove or the like by laser. Then, although the tearing property is improved, at the same time, stress is concentrated on the weakened portion, and the material strength required for processing and handling is impaired, and the strength against drop and other impacts is also reduced at the same time. .

Further, in these processing methods, there is a problem that the control of the processing is very difficult, and processing chips are generated. For example, in the processing method using a cutting tool, a cutting tool in which a number of fine and sharp blades are arranged or a single cutting tool is pressed against a packaging material to perform the processing. However, there is a problem that the cutting thickness is greatly changed due to the pressing force. In order to solve this problem, it is necessary to increase the mechanical accuracy of the processing machine. However, there are problems that the productivity is reduced and the equipment cost is increased. Further, there is also a problem that a large number of fine powders of the packaging material are generated due to cutting or abrasion, and this is mixed into the product.

Furthermore, in the processing method using a laser, a laser beam is focused on a surface of the packaging material by a plano-convex lens or the like into a spot of about 0.2 mm to volatilize the plastic on the packaging material surface, thereby forming a groove or a line. However, even when the packaging material position slightly fluctuates up and down, the packaging material may be completely or excessively cut, and in order to keep the processing state constant, the accuracy of the processing machine is greatly increased. However, there is also a problem that the productivity is lowered and the cost of the apparatus is increased. Further, there is also a problem that a part of the packaging material sublimes at a high temperature, fumes are generated, and adhere to the packaging material. To prevent this, fume exhaust is required.

The present inventors use a laminate made of a thermoplastic resin in which at least the outer surface layer and / or the intermediate layer is molecularly oriented as a packaging bag, and a width in a direction crossing the opening direction is larger than 1 mm. A laser beam having an intensity such that the outer surface resin layer and / or the intermediate resin layer is melted but not substantially scattered is irradiated continuously or discontinuously along the surface. It has been found that by forming a melt-weakened resin layer on the base material, a flaw-less easily tearable portion free of the above-mentioned conventional method can be formed.

That is, an object of the present invention is to impart easy tearing property, that is, easy tearing property, without substantially causing wear and the like of the packaging material, and further without reducing the sealing strength and the impact strength of the sealing portion. And a method for producing the same.

Another object of the present invention is to provide a method for producing an easily tearable packaging bag, which can easily impart high tearability without requiring special troublesome control and with high productivity. It is in.

According to the present invention, at least the outer surface layer and / or the intermediate layer are formed by stacking a laminate made of a thermoplastic resin having molecular orientation, and the bag is formed, and at least the tear start portion or the vicinity thereof is weakened. In the easily tearable packaging bag, at least the outer surface resin layer and / or the intermediate resin layer at or near the tear start portion is continuously or discontinuously over a range in which the width in the direction crossing the opening direction is larger than 1 mm. An easily tearable packaging bag, wherein a melt-weakening resin layer distributed in a plane direction is formed.

According to the present invention, a laminate made of a thermoplastic resin in which at least the outer surface layer and / or the intermediate layer is molecularly oriented is stacked to form a bag, and at any stage of bag production, at least at the tear start portion or in the vicinity thereof. In the method of forming the weakened portion, at any stage of bag production, at least the opening start portion or the outer surface resin layer and / or the intermediate resin layer in the vicinity of the opening start portion over a range in which the width in the direction crossing the opening direction is larger than 1 mm. Irradiating a laser beam having an intensity such that the outer surface resin layer and / or the intermediate resin layer is melted but not substantially scattered, continuously or discontinuously along the surface, whereby the irradiation is performed. A method for producing an easily tearable packaging bag, characterized in that a melt-weakening resin layer is formed in a portion.

In the easily tearable packaging bag of the present invention,
1. At least the outer surface resin layer and / or the intermediate resin layer near the tear initiation portion or in the vicinity thereof is a weakened resin layer due to relaxation or disappearance of molecular orientation,
2. In some cases, in addition to this, at least the outer surface resin layer and / or the intermediate resin layer at or near the opening start portion may be JIS
K 0068 is a thermoplastic resin having a moisture content of 0.1% by weight or more and forms a weakened resin layer by foaming;
3. At least the tear start portion or the outer surface resin layer and / or the intermediate resin layer in the vicinity of the tear start portion are made of a fine dot-like or stripe-like weakened resin layer arranged almost regularly,
4. The dot-shaped or stripe-shaped weakened resin layer has a pitch of 20 to 5000 μm;
5. The outer surface layer or the intermediate layer of the laminate is made of at least a uniaxially stretched polyester, polyamide or olefin resin film,
6. The laminate is a laminate having a layer configuration of thermoplastic polyester / metal foil / olefin resin in order from the surface,
7. The laminate is a laminate having a layer structure of thermoplastic polyester / nylon / metal foil / olefin resin in order from the surface,
8. The weakened portion emits a laser beam having such an intensity that the outer surface resin layer and / or the intermediate resin layer is melted but substantially not scattered over a range having a width in a direction transverse to the opening direction larger than 1 mm. It is preferably formed by irradiating continuously or discontinuously along the surface.

In the method for producing an easily tearable packaging bag of the present invention,
1. 1. irradiate the laser beam through a kaleidoscope, or Irradiation of a laser beam is preferably performed through a cylindrical lens, and particularly preferably through a callide scope.

According to the present invention, the advantage that the thermoplastic resin layer is molecularly oriented by forming the molten resin weakened layer using the molecular orientation of the outer surface layer and / or the intermediate layer of the laminate is provided. While preserving, it is possible for this melted part to form a part that is weakened to tearing selectively.

In addition, the melting weakening of the tear start portion or the vicinity thereof is performed such that the width in the direction crossing the opening direction is larger than 1 mm and is distributed continuously or discontinuously in the plane direction, so that melting is performed. Can be dispersed over a range wider than 1 mm, whereby it is possible to avoid fusing due to local heating and evaporation of resin. Not only that, it also increases the tolerance for displacement of the tear start position, enables smooth tearing, improves easy tearing, and further disperses the stress applied to the melt-weakened resin layer, causing accidental breakage due to impact, etc. It is also possible to prevent bags. In addition, even if there is a slight deviation between the position of the molten resin weakened layer provided on the front side laminate and the position of the molten resin weakened layer provided on the back side, the width is larger than 1 mm, so that the two overlap. , And the opening by smooth and reliable tearing becomes possible.

Further, when the outer surface resin layer and / or the intermediate resin layer is a thermoplastic resin having a moisture content of 0.1% by weight or more according to JIS K 0068, the orientation is reduced by melting and the moisture is weakened by foaming of the resin. This also causes the resin layer to weaken more effectively.

According to a preferred embodiment of the present invention, at least a tear start portion or an outer surface resin layer and / or an intermediate resin layer in the vicinity of the tear start portion are formed with a finely dot-like or stripe-like weakened resin layer which is arranged substantially regularly, In such a resin melting weakened layer, the molecular orientation portion and the melting portion of the thermoplastic resin are mixed, and the advantages of both are achieved in combination.

In the present invention, the molecular orientation of the thermoplastic resin is used for the outer surface layer and / or the intermediate layer of the laminate used for bag making because the molecular orientation of the thermoplastic resin is higher than the mechanical strength and the resistance of the laminate. This is because impact resistance, gas barrier properties, heat resistance, transparency and the like are improved. Further, the uniaxial orientation of the thermoplastic resin also has an effect of improving tearability in the orientation direction.

で は In the present invention, the weakened layer is formed by utilizing the molecular orientation of the outer surface layer and / or the intermediate layer of the laminate. In the state where the thermoplastic resin layer is molecularly oriented, particularly in the state of being biaxially oriented, the tear initiation strength of the resin layer is naturally improved, but in the present invention, the outer surface layer and / or the intermediate layer of the laminate is melted, By relaxing or eliminating this molecular orientation, it becomes possible to form a portion which is selectively weakened against tearing in the molten portion.

Further, when the outer surface resin layer and / or the intermediate resin layer is a thermoplastic resin having a moisture content of 0.1% by weight or more according to JIS K 配 向 0068, the orientation is reduced by melting and the weakening is caused by foaming of moisture in the resin. This also causes the resin layer to weaken more effectively.

It is also important that the melt weakening in the tear initiation portion or the vicinity thereof in the present invention is performed continuously or discontinuously in the plane direction over a range where the width in the direction crossing the opening direction is larger than 1 mm. is there. That is, by dispersing the heat for melting over a range wider than 1 mm, it is possible not only to avoid fusing due to local heating and evaporation of the resin, but also tolerating the shift of the tearing start position. , The smooth tearing is enabled to improve the easy tearing property, and the stress applied to the melt-weakening resin layer is dispersed to prevent accidental bag breakage due to impact or the like. In addition, even if there is a slight deviation between the position of the molten resin weakened layer provided on the front side laminate and the position of the molten resin weakened layer provided on the back side, the width is larger than 1 mm, so that the two overlap. , And the opening by smooth and reliable tearing becomes possible.

In the present invention, it is particularly preferable that at least the outer surface resin layer and / or the intermediate resin layer in the vicinity of the tear initiation portion or in the vicinity thereof are composed of a weakly dot-like or stripe-like weakened resin layer that is arranged substantially regularly. This is because in such a resin melt-weakening layer, the molecular orientation portion and the melt portion of the thermoplastic resin are mixed, and the advantages of both are achieved in combination. In this case, the tearing is performed in such a manner as to pass through the dots or stripes. In addition, it is preferable that the dot-shaped or stripe-shaped weakened resin layer has a pitch of 20 to 5000 μm in order to impart easy tearability without lowering the bag breaking strength of the bag.

Further, it is preferable that the outer surface layer or the intermediate layer of the laminate is made of at least a uniaxially stretched film of polyester, polyamide or olefin resin. This is because these resins are easy to be uniaxially or biaxially oriented, have a large improvement in physical properties due to the orientation, and are easy to relax or lose the orientation due to melting. In the case of polyester and polyamide, promotion of weakening due to foaming during melting can also be expected.

に お い て In the method of the present invention, it is important to form the melt weakened portion by laser irradiation. That is, by performing laser irradiation on the outer surface resin layer and / or the intermediate resin layer in the vicinity of the tear initiation portion or in the vicinity thereof over a range where the width in the direction crossing the opening direction is larger than 1 mm, the outer surface resin layer and / or the intermediate Heating can be performed to such an extent that the resin layer is melted but does not substantially scatter, thereby preventing loss of the resin material and without excessively reducing the strength of this portion. This makes it possible to form an easily tearable melt-weakened resin layer. In the present invention, the tear start portion is generally an opening start portion, but also includes a tear start portion different from the opening start portion.

[Laminate] In the present invention, the flexible laminate constituting the container wall of the packaging bag includes a stretched plastic film for imparting mechanical strength and heat resistance, an olefin resin for imparting heat sealability, Alternatively, a metal foil or a gas-barrier resin or the like for imparting a gas-barrier property to oxygen or the like is used in a laminate form in a plurality of combinations.

As the stretched plastic film, polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, ethylene terephthalate / isophthalate copolymer: nylon 6, nylon 6, 6, nylon 11, nylon 12, nylon 6 / Polyamide (Ny) films such as nylon 6,6 copolymer and aromatic nylon: propylene polymer film (PP): polyvinyl chloride film: polyvinylidene chloride film: ethylene vinyl alcohol copolymer film (EVOH) Can be mentioned. These films may be a blend or a multilayer, and may be uniaxially stretched or biaxially stretched. It is desirable that the thickness is generally in the range of 3 to 50 μm, particularly 5 to 40 μm.

On the other hand, heat-sealing resin films generally include low-, medium-, and high-density polyethylene (PE), linear low-density polyethylene, isotactic polypropylene (PP), propylene-ethylene copolymer, ethylene-acetic acid. Vinyl copolymer, ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ion-crosslinked olefin copolymer (ionomer), olefin resin graft-modified with ethylenically unsaturated carboxylic acid or anhydride thereof, etc. A modified olefin resin; a polyamide or copolyamide resin having a relatively low melting point or low softening point; or a polyester or copolyester resin having a relatively low melting point or low softening point; Is done. These films preferably have a thickness of 15 to 100 μm.

On the other hand, as metal foil used for imparting gas barrier properties, various surface-treated steel foils and light metal foils such as aluminum (Al) are used. As the surface-treated steel foil, one or two or more kinds of surface treatment such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment are performed on cold-rolled steel foil, or prior to final rolling. Then, a surface-treated steel foil obtained by performing the plating treatment and then performing the cold rolling treatment can be used. As the light metal foil, aluminum alloy foil is used in addition to so-called pure aluminum. These metal foils have a thickness of 150 μm or less, particularly 5 to 120 μm.

As the gas barrier resin, a thermoplastic resin having a low oxygen permeability coefficient and being thermoformable is used. The most suitable example of the gas barrier resin is an ethylene-vinyl alcohol copolymer (EVOH). For example, ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 60 mol%, particularly 25 to 50 mol%. A saponified copolymer obtained by saponifying a vinyl acetate copolymer so as to have a saponification degree of 96 mol% or more, particularly 99 mol% or more is used. The saponified ethylene-vinyl alcohol copolymer should have a molecular weight sufficient to form a film and is generally 0.01 dL measured at 30 ° C. in a 85:15 phenol: water mixture by weight. / g or more, especially 0.05
It is desirable to have a viscosity of dL / g or more.

Other examples of the gas barrier resin having the above-mentioned properties include polyamides having an amide group number of 5 to 50, particularly 6 to 20, per 100 carbon atoms; for example, nylon 6, nylon 6,6, nylon 6 / 6,6 copolymer, meta-xylylene adipamide, nylon 6,10, nylon 11, nylon 12, nylon 13, hexamethylene terephthalamide / isophthalamide copolymer, or a blend thereof Things etc. are used. These polyamides should also have a molecular weight sufficient to form a film and have a relative viscosity (ηrel) measured at a concentration of 1.0 g / dl in concentrated sulfuric acid at a temperature of 30 ° C. of 1.1.
It is desirable that it is 1.5 or more.

These gas barrier resins are used in a thickness of 3 to 50 μm, especially 5 to 30 μm.

Suitable examples of the laminate have a layer structure from the inside to the outside, and include an olefin resin heat seal layer / uniaxially stretched polypropylene film, an olefin resin heat seal layer / biaxially stretched nylon film, and an olefin resin heat seal layer / 2. Axial stretched polyethylene terephthalate film, olefin resin heat seal layer / aluminum foil / biaxially stretched polypropylene film, olefin resin heat seal layer / aluminum foil / biaxially stretched nylon film, olefin resin heat seal layer / aluminum foil / biaxial Stretched polyethylene terephthalate film, olefin resin heat seal layer / ethylene vinyl alcohol copolymer / biaxially stretched polyester film, olefin resin heat seal layer / amorphous aromatic polyamide / biaxially stretched polyethylene Emissions terephthalate film, but an olefinic resin heat seal layer / metallized biaxially oriented polyethylene terephthalate film or the like, not limited to this example. For example, a paper layer can be provided as the outermost layer or a layer below the outermost layer.

In FIG. 1, which shows an example of a laminate preferably used in the present invention, the laminate 1 has an outer layer 2 made of thermoplastic polyester (PET), an intermediate layer 3 made of metal foil, and an olefin resin in order from the surface. Of the inner layer 4 for heat sealing. In FIG. 2 which shows another example of a suitable laminate, this laminate 1 comprises an outer layer 2 of thermoplastic polyester / a second intermediate layer 5 of nylon / a first intermediate layer 3 of metal foil / olefin. It has a layer structure of a heat sealing inner layer 4 of a system resin.

The total thickness of the laminate 1 is preferably in the range of 20 to 200 µm, particularly 30 to 150 µm. When the thickness is smaller than the above range, the bag breaking strength is reduced, and it is difficult to selectively form a melt-weakening layer of the outer surface layer and / or the intermediate layer of the laminate in the thickness direction. In addition, the flexibility of the bag is lost, and it is difficult to impart tearability.

The production of the laminate can be carried out by any known means such as dry lamination, sandwich lamination, extrusion coating, coextrusion and the like. When sufficient adhesiveness cannot be obtained between the layers, an adhesive resin such as a urethane-based adhesive, an epoxy-based adhesive, and an acid-modified olefin-based resin adhesive can be used.

In addition, in sandwich lamination, it is performed by extruding an arbitrary resin between the films or between the film and the resin-coated metal foil, and in extrusion coating, extruding an arbitrary resin on the film or the metal foil. Done. Extruded resins are generally low-, medium-, high-density polyethylene, linear low-density polyethylene, isotactic polypropylene, propylene-ethylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer. Modified olefin resins such as coalesced copolymers, ethylene-methyl methacrylate copolymers, ion-crosslinked olefin copolymers (ionomers), and olefin resins graft-modified with ethylenically unsaturated carboxylic acids or anhydrides; Polyester or copolyamide resin having a softening point; polyester or copolyester resin having a relatively low melting point or low softening point; a blend resin comprising one or more of the above resins and / or a known filler; Layer extrusion or coextrusion is used. A urethane-based or titanate-based anchor agent can be applied to the surface on which the extruded resin layer is to be formed.

[Packaging bag and manufacturing method thereof] The easily tearable packaging bag of the present invention is formed by stacking the above-mentioned laminates so that the heat-sealable resin layers face each other, and forming the bag by heat sealing or the like. .

In FIG. 3 showing an example of the packaging bag of the present invention (three-side heat seal pouch), this easily tearable packaging bag 10 has a folded part 11 on one side and edge heat seal parts 12a, 12b, 12c on three sides. A melt-weakened portion 13 is formed on at least a part of the folded portion 11, preferably, at least three edge heat-seal portions 12a, 12b, and 12c. This melting weakened part 13 becomes an opening start part. This type of packaging bag is manufactured by stacking one laminate and heat-sealing the three sides. The heat sealing is performed under a temperature condition in which the heat-sealing resin is melted but the outer surface and / or the resin layer having the molecular orientation of the intermediate layer is not substantially melted, and the same applies to the following examples. The formation of the melt weakened portion 13 is performed by a method described later.

In FIG. 4 showing another example of the packaging bag of the present invention (four-side heat seal pouch), this easily tearable packaging bag 10 has edge heat seal portions 12a, 12b, 12c, and 12d on four sides. At least a part of the edge heat seal portions 12a, 12b, 12c, and 12d has a melt weakening portion 13 formed therein. The melt-weakened portion 13 is also the opening start portion.

In FIG. 5, which shows still another example of the packaging bag of the present invention (pillow packaging pouch), this easily tearable packaging bag 10 is formed by a heat-sealed apod 14 extending to the center and folded portions on both sides parallel to the apod. 11a and 11b, and edge heat seal portions 12a and 12b in a direction perpendicular to the palm joint, and these folded portions 11a and 11b are preferably folded together 14 or two edge heat seal portions 12a and 12b. Is formed with a melt weakening portion 13 in at least a part thereof. The melt-weakened portion 13 is also the opening start portion.

包装 In the packaging bag of the present invention, the width of the heat seal in the edge heat seal portion and the gas seal bonding is preferably in the range of 3 to 15 mm from the viewpoint of prevention of bag breakage and reduction of materials used. In the present invention, utilizing the fact that the outer surface layer and / or the intermediate layer of the laminate of these heat seal portions maintains the molecular orientation substantially as it is, the formation of the melt-weakened resin layer, that is, the tear initiation portion Is formed.

In the pillow packaging pouch of the present invention, when the weakening portion 13 is provided along the intersection of the palm joint 14 and the edge seal portion 12, the palm joint 14 is used as a grip portion, and the pouch wall along the joint palm 14 is torn. This is convenient because the scheduled portion can be unsealed along the palm joint 14. Further, when the edge seal portion 12 is made of an easily peelable seal and a second weakened portion 13a is provided near the end portion of the seal portion, the palm joint 14 serves as a grip portion, and the valley fold portion of the joint palm 14 serves as a grip portion. The tear along the palm joint 14 and the peeling of the edge seal portion 12 are performed by setting the vicinity of the folded portion 11a as a scheduled tear portion, the weakened portion 13 as an opening start portion, and the weakened portion 13a as a tear start portion near the folded portion 11a. This is convenient because opening is possible.

[Melt weakened resin layer and its formation]
In the present invention, the melting weakening of the tear start portion or the vicinity thereof is continuously or discontinuously performed in a range in which the width in the direction transverse to the opening direction is larger than 1 mm, preferably 2 mm to the length of the bag. It is important that the distribution is carried out.

That is, when the width is 1 mm or less, the melting of the laminate and the evaporation of the resin due to local heating are likely to occur, and a slight shift in the tearing start position tends to make smooth tearing difficult. Further, stress concentration tends to occur in the melt-weakened resin layer, and the tendency of accidental bag breakage due to impact or the like increases.

寸 法 The size of the melt-weakened portion in the opening direction is not particularly limited as long as the tear initiation portion is formed, and is generally 0.5 mm or more, particularly preferably in the range of 2 to 10 mm. If this dimension is too small, it tends to be difficult to form a tear initiation sufficient to continue the tear.

Further, the shape of the fusion weakened portion may be any shape such as a triangle, a square, a rectangle, a diamond, a hexagon, a circle, an ellipse, a semicircle, an irregular shape, and the area thereof corresponds to the dimensions described above. , Generally in the range of 1 to 300 mm ² .

Further, the depth at which the melt-weakened portion is to be formed may extend over the entire outer surface layer and / or the intermediate layer of the laminate, at least 30% or more of the thickness of the outer surface layer and / or the intermediate layer of the laminate, In particular, it is preferably over 50%.

The fact that the molecular orientation has disappeared or relaxed in the melt-weakened portion of the outer surface layer and / or the intermediate layer of the laminate can be measured by known measurement means such as a birefringence method, an X-ray diffraction method, and a fluorescent birefringence method. It can be confirmed by law.

In the present invention, the melt-weakened portion can be provided in a so-called solid state that is continuous in the surface direction, or can be provided in the form of fine dots or stripes arranged substantially regularly.

In FIG. 6 showing the surface state of the tear start portion due to melt weakening, A shows an example in which the tear start portion 20 is formed of a solid melt weakened resin layer 13, and B and B ′ show the tear start portion 20. Indicates an example in which the stripe-shaped melt-weakened resin layer 13 is formed, and C indicates an example in which the tear start portion 20 is formed of the dot-shaped melt-weakened resin layer 13.

ＡIn the example of FIG. 6A, the alignment resin layer 21 exists outside the tear start portion 20, but the melt weakening resin layer 13 only exists inside the tear start portion 20, and the alignment resin layer does not exist. In the example of FIG. 6B, the alignment resin layer 21 exists outside the tear start portion 20, and the stripe-shaped melt-weakening resin layer 13 and the stripe alignment resin layer 21 also exist inside the tear start portion 20. Exist alternately and repeatedly. In the example of FIG. 6C, the alignment resin layer 21 exists outside the tear start portion 20, and the molten resin layer 13 is located inside the sea of the alignment resin layer 21 inside the tear start portion 20. It exists in a state of becoming.

に お い て In the present invention, the melt-weakening resin layer 13 preferably exists as a large number of dots or stripes at the tear start portion 20, and particularly preferably as a large number of dots. It has already been pointed out that in such a melt-weakened resin layer, the molecular orientation portion and the melt portion of the thermoplastic resin are mixed and the advantages of both are achieved in combination.

Further, regardless of the ratio between the dot-shaped or striped melt-weakened resin layer and the unmelted portion, the melt-weakened resin layer has a pitch of 20 to 5000 μm, especially 50 to 2000 μm, which lowers the breaking strength of the bag. It is preferable for imparting easy tearability without performing the above. Further, it is preferable that the dot diameter or the stripe width is in the range of 20 to 5000 μm, particularly 50 to 2000 μm.

で は In the present invention, the formation of the melt-weakened portion is not particularly limited, but is preferably formed by laser irradiation. That is, by performing laser irradiation on the outer surface resin layer and / or the intermediate resin layer in the vicinity of the tear initiation portion or in the vicinity thereof over a range where the width in the direction crossing the opening direction is larger than 1 mm, the outer surface resin layer and / or the intermediate Heating can be performed to such an extent that the resin layer is melted but does not substantially scatter, thereby preventing loss of the resin material and without excessively reducing the strength of this portion. This makes it possible to form an easily tearable melt-weakened resin layer.

に お い て In the present invention, the molten resin layer may be in an amorphous or low crystallized state, or may be in a thermally crystallized state. A very limited part of the oriented crystallized resin from the surface to the middle in the thickness direction is rapidly heated to a temperature higher than the melting point in a short time, and rapidly cooled to a temperature lower than the crystallization temperature when the heating is stopped. As a result, the molten resin layer is in an amorphous state or a low-crystal state. In the case of the amorphous portion or the low crystallization portion, the impact resistance of the processed portion is maintained at a high level. On the other hand, if the time during which the molten resin layer passes through the crystallization temperature region is long, the tendency of the molten resin layer to thermally crystallize increases. Thermal crystallization of the molten resin layer also occurs when the heat treatment temperature range of the packaging bag and the crystallization temperature range of the outer layer or intermediate layer resin overlap, such as in hot filling or retort sterilization. When the molten resin is thermally crystallized, it becomes somewhat brittle in nature, providing the advantage of improved tearability. For such limited rapid heating and rapid cooling, for example, instantaneous irradiation or scanning irradiation of a carbon dioxide laser beam can be used. In this case, the output of the laser beam and the irradiation time or scanning speed are changed. Thereby, the thickness and temperature of the molten layer can be controlled. Further, the width can be controlled by changing the diameter of the laser beam. The laser output is appropriately selected depending on the type of the constituent base material and the material of the ink layer. Conversely, if the degree of processing is increased, a material having a large infrared absorption is selected.

In one embodiment of the present invention, a laser beam is condensed by a planoconvex lens (a lens whose one surface is flat and the other surface is convex) and is irradiated in a state where it is defocused on the laminate. If necessary, scanning irradiation is performed to secure a predetermined irradiation area.

In FIG. 7 for explaining this embodiment, a laser beam 30 is condensed by a plano-convex lens 31 (flat surface 32, convex surface 33) and defocused on the laminated body 1, that is, from the focus distance f. Irradiation is performed with only the defocus distance f _{0 set} .

Considering the case of normally irradiating a laser beam, it is usual to focus on the position of the laminated body (f). In this case, the intensity distribution of the laser beam has a steep Gaussian like a curve a in FIG. Distribution. Therefore, the width is narrow (half width H ₀ ), the strength at the center is high, and the surface temperature of the laminate is high. On the other hand, in the present invention, as shown in FIG. 7, the focal point is shifted (defocused) and the laminate is irradiated. By doing so, as shown in the curve b in FIG. 8, intensity distribution of the laser beam becomes a smooth Gaussian distribution (half width _{H 1, H 1 >> H 0} ). Therefore, the central portion does not become hot, there is no fume generation, and a wide weakened portion is machined. As the condensing lens, a known lens such as a meniscus lens, a non-curved lens, or a biconvex lens can be arbitrarily used in addition to the planoconvex lens.

In another preferred embodiment of the present invention, the laser beam is condensed by a cylindrical lens (a semi-cylindrical lens, one surface of which is flat, the other surface of which is convex and extends in the longitudinal direction), and is scanned in the processing direction. Irradiation is performed.

In FIG. 9 for explaining this embodiment, a laser beam 30 is condensed by a cylindrical lens 34 (flat surface 32, convex surface 35) and is irradiated onto the laminate 1 while scanning in the processing direction X. In this case, the laser beam is focused on a line, and a broad focused beam in a direction parallel to the curved surface has an almost uniform intensity distribution.By scanning this focused beam in a direction perpendicular to the line beam, The weakened portion 13 having a substantially quadrangular shape and a solid shape can be machined. Further, the stripe-shaped weakened portion can be processed by irradiating it through one or several masking slits parallel to the scanning direction.

In the most preferred embodiment of the present invention, the laminate is irradiated with a laser beam through a kaleidoscope onto the laminate. If necessary, scanning irradiation is performed to secure a predetermined irradiation area.

In FIG. 10 for explaining the kaleidoscope, the kaleidoscope 36 is a rectangular parallelepiped cylinder made of metal, and has holes 37 of various shapes in the vicinity of the center, and the inner surface 38 has a high reflectance. It is gold plated or the like. In a portion where the wavelength of the laser light reflected by the inner surface 38 is shifted by an integral multiple, the light overlaps, and in a portion where the wavelength is shifted by a half wavelength, the light cancels out, and a fine interference pattern 40 is formed.

When the laser beam 30 is condensed by the planoconvex 31 at the cavity entrance 37 of the kaleidoscope 36, the laser beam at the exit of the kaleidoscope 36 has a rectangular cross section as shown in FIG. It becomes a point-like aggregate beam. By scanning this beam, a large number of stripe-shaped scanning beams as shown in FIG. 12 are formed. As a result, the strength of the packaging material does not decrease, and the tearability does not decrease.

In the point-like collective beam from the kaleidoscope, the distance and size of each point are determined by the distance from the outlet of the kaleidoscope to the laminate (the distance increases as the distance increases, but the intensity decreases) and the cross section. And the length of the kaleidoscope.

It is also possible to change the size of the entrance and the size of the exit of the cavity of the kaleidoscope, which has the advantage that a very large weakened portion can be machined. For example, as shown in FIG. 13A, if the entrance has a size of 5 mm × 3 mm and the exit has a size of 18 mm × 3 mm, the size of the point-like aggregate beam is about 5 mm × 20 mm. . Further, the pattern of the point-like aggregate beam is as shown in FIG.

Further, when the kaleidoscope is tilted from the optical axis of the planoconvex lens as shown in FIG. 14A, the interval between the points of the point beam increases in the tilted direction as shown in FIG. 14B.

Furthermore, as shown in FIG. 15, the shape of the entrance 37 of the cavity of the kaleidoscope may be a triangle, a hexagon, or the like, in addition to a square. In this case, if the hollow portion is a triangular prism or a hexagonal prism, a triangular or hexagonal resin melting weakened portion in which a number of dot-shaped resin melting portions are scattered is obtained.

FIG. 16 shows the result of observing a processing pattern when a workpiece is irradiated with a laser beam for a short time when the shape and dimensions of the cavity entrance of the kaleidoscope are 5 mm × 5 mm. The surface of the workpiece is melted to form a fine uneven pattern. The pitch between the points was about 0.3 mm.

炭 酸 In the present invention, a carbon dioxide laser is used as the laser beam, and generally, the output of the laser beam is preferably in the range of 10 W to 1.2 kW, but is not limited to this.

In addition, in the present invention, an infrared lamp or a hot plate can be used as a heat source other than the laser.

For example, as shown in FIG. 17A, an infrared lamp 46 is installed at the focal point of a parabolic mirror 45 whose inner surface is gold-plated, and a kaleidoscope 36 is installed at the other focal point of the parabolic mirror 45. . As a result, an infrared beam 47 having a substantially square area and a large area as shown in FIG. 17B can be formed.

The processing method using a laser beam or an infrared lamp can process the laminate without contact, so the application is very simple.However, when using a hot plate, the position to be processed at the weakened part of the laminate material Then, it is necessary to press the hot plate for a certain period of time.

FIG. 18 shows a schematic diagram of the heat bar. The tip of the heat bar 50 has a substantially square shape, and is provided with a fine mesh ceramic coating 51. A coating that does not stick even when it comes into contact with the processed surface of the laminate, such as a coating of polytetrafluoroethylene, is desirable. A cartridge heater 52 is incorporated in the main body of the heat bar 50, and the temperature is detected by a thermocouple 53 inserted therein, the power supplied to the heater 52 is adjusted, and the temperature of the tip of the heat bar is kept constant. It is controlled to become. By pressing the tip of the heat bar against the laminated material, it can be processed into a weakened portion as shown in FIG. 18B.

In the present invention, the formation of the weakened layer by melting the resin can be performed before, during or after bag making. For example, a laser beam or an infrared beam is irradiated on a molecular orientation film to be a surface layer before, during lamination, or after lamination, or an intermediate layer at an arbitrary stage for manufacturing a laminate, and Melt weakened portions of the pattern can be formed.

In FIG. 19, which shows an example of a laminate to be applied to bag making, the laminate 1 has a portion 15 to be folded back to opposed sheet portions 17a and 17b, and three portions 16a, 16b and 16c to be heat-sealed. The weakened layer 13 is formed at the edge of the upper sealing portion 16b of both sheet portions 17a, 17b. In this case, since the melt-weakened layer 13 is formed over a width of 1 mm or more, the distance L1 from the portion 15 to be folded to the melt-weakened layer 13 of one sheet 17a and the distance L1 from the portion 15 to be folded to the other sheet 17b Even if the distance L2 to the melt-weakened layer 13 does not exactly match and there is some deviation between the two, the packaging bag can be smoothly torn and opened by hand.

In the packaging bag of the present invention, a slit or the like for guiding the tearing of the laminate may be provided by a means known per se, but after the slit formation or in the slit inspection step, the formation of the melt-weakened layer is performed. May be performed. Further, in the unwinding step of the laminate in the bag making step, or after the bag making, a melt-weakening layer can be formed at a predetermined position of the packaging bag, and before or after filling the contents into the packaging bag. The formation of a melt weakened layer can be performed.

The present invention will be specifically described with the following examples. Seven types of laminates shown in Table 1 were prepared.

注１） 表中の／記号はサンドイッチラミネーションによる接着界面を示し、PETとAlの接着面には必要に応じてウレタン系のアンカー剤をコーティングした。また、表中の記号・はウレタン系接着剤を用いてドライラミネーションした接着界面を示す。
注２） 表中の（　）内の数値は各基材の厚さを示す。
注３）表中、略号で示した基材はそれぞれ以下のものを示す。
PET：ラミネート面に印刷を施した二軸延伸ポリエチレンテレフタレートフィルム（東レ　ルミラー　Ｐ−６０）。
PA-1：二軸延伸ナイロン６フィルム（ユニチカ　エンブレム　ＲＴ）。
PA-2：ラミネート面に印刷を施した二軸延伸ナイロン６フィルム（興人　ボニール　ＲＸ）。
Al：アルミニウム箔。
EVOH：二軸延伸エチレンビニルアルコール共重合体フィルム（クラレ　ＥＦ−ＸＬ）。
UOPP：ラミネート面に印刷を施した圧延による一軸延伸ポリプロピレンフィルム（日石　バリーラ　ＰＧ）。
CPP：ポリプロピレンのキャストフィルム。
LDPE：押出コート用低密度ポリエチレン層。
LLDPE：線状低密度ポリエチレンフィルム。
HDPE：高密度ポリエチレン横延伸フィルム（東洋化学　カラリヤンＹ）。

Note 1) The symbol “/” in the table indicates the bonding interface by sandwich lamination, and the bonding surface between PET and Al was coated with a urethane-based anchor agent as necessary. In addition, the symbol “・” in the table indicates an adhesive interface dry-laminated using a urethane-based adhesive.
Note 2) The values in parentheses in the table indicate the thickness of each substrate.
Note 3) In the table, the base materials indicated by abbreviations are as follows.
PET: Biaxially stretched polyethylene terephthalate film (Toray Miller P-60) printed on the laminate surface.
PA-1: Biaxially stretched nylon 6 film (Unitika Emblem RT).
PA-2: A biaxially stretched nylon 6 film having a printed surface on the laminate surface (Kojin Bonyl RX).
Al: aluminum foil.
EVOH: Biaxially stretched ethylene vinyl alcohol copolymer film (Kuraray EF-XL).
UOPP: Rolled uniaxially stretched polypropylene film (Nisseki Vallilla PG) printed on the laminate surface.
CPP: Cast film of polypropylene.
LDPE: Low density polyethylene layer for extrusion coating.
LLDPE: Linear low density polyethylene film.
HDPE: high-density polyethylene laterally stretched film (Toyo Kagaku Karalyan Y).

[Examples 1-1, 2, 3 and Comparative Examples 1, 2, 3]
Using the laminates 1, 3, and 5 having a width of 100 mm, a pouch having a 4-mm width edge heat seal portions 12a and 12c of the three-way heat seal pouch shown in FIG. Created using The weakened portion was obtained by intermittently unwinding the laminate from a roll using a photoelectric mark, and processing the PET surface of the outer layer by laser. As shown in FIG. 19, two processing places were provided at the same position on the front and back of the pouch when bent at the folded portion 15 of the laminate 1. The processing was performed as shown in FIG. 14 using a carbon dioxide laser beam through a planoconvex to form a point-like aggregate beam with a kaleidoscope at a laser output of 60 W and an irradiation time of 60 msec. The focal length of the planoconvex lens was 2.5 inches, the length of the kaleidoscope was 138 mm, the entrance of the cavity was a rectangle of 3 mm × 6 mm, and the exit was a rectangle of 6 mm × 6 mm. Further, the distance between the exit surface of the kaleidoscope and the laminate was adjusted to 8 mm. The pouches of Examples 1-1, 2, and 3 thus prepared have a large number of dot-shaped weakened portions, a pitch of about 0.3 mm, a length of 6 mm in the longitudinal direction of the heat seal portion, and a width of 3 mm in the width direction. Was scattered throughout the range. When a section was cut out from this portion and observed with a polarizing microscope, the outer surface PET was melted by laser processing in the weakened portion, and the orientation was relaxed or lost. In these pouches, even when the contents were filled with liquid soup or the like, there was nothing that broke from the melt-weakened part. In addition, the displacement of the melt-weakened portion on the front and back of the pouch is about 1.2 mm in the longitudinal direction of the edge heat-sealed portion 12, and the melt-weakened portion easily tears from the overlapping portion on both sides without a notch. I was able to. Similarly, in the pouches of Comparative Examples 1, 2, and 3, which were prepared using the laminates 1, 3, and 5 without performing laser processing, the pouches could not be torn from the edge heat seal portion 12.

[Comparative Examples 4, 5, 6]
In the same manner as in Examples 1-1, 2, and 3, three-sided heat seal pouches having a weakened portion for opening start using the laminates 1, 3, and 5 were prepared. However, the weakened portion was formed by unwinding the laminate continuously from a roll and using a photoelectric mark to intermittently process the fixed position on the PET surface of the outer layer with a laser. The laser processing was performed by condensing a carbon dioxide laser beam with a planoconvex lens, positioning the laminated body at a focal length of approximately 2.5 inches, with a laser output of 3 W and an irradiation time of about 60 msec. During processing, the outer PET layer sublimated, a large amount of fume was generated, and the lens was soiled. Observation of the weakened portion showed that the PET layer had completely disappeared, its length was 3 mm and its width was about 0.2 mm. In the pouches of Comparative Examples 5 and 6 using the laminates 3 and 5, the aluminum foil was exposed on the outer surface. When these pouches were filled with a liquid soup or the like, in Comparative Example 5 using the laminate 3, there was a case in which the bag was broken in a transport test or the like because the remaining base material in the weakened portion was thin. Also, the displacement of the weakened portion on the front and back of the pouch was approximately 1.2 mm in the longitudinal direction of the edge heat-seal portion 12 as in Examples 1-1, 2, and 3, but the base material was not In Comparative Examples 4 and 6 using the laminates 1 and 5 remaining thick, tearing could not be easily performed.

[Examples 1-4, 5, 6]
Similarly to Comparative Examples 4, 5, and 6, three-sided heat seal pouches having a weakened portion for opening start using the laminates 1, 3, and 5 were prepared. However, the laminated body was processed at a laser output of 75 W at a position defocused by 12 mm below the focal point. In Examples 1-4, 5, and 6, no fume was generated at the time of processing, and the PET layer on the outer surface did not sublime but only melted. In the weakened portion, the orientation of the outer PET layer was relaxed or disappeared. Further, the length of the melt-weakened portion was 3 mm and the width was about 1.1 mm. In these pouches, even when the contents were filled with liquid soup or the like, there was nothing that broke from the melt-weakened part. In addition, the displacement of the melt-weakened portion on the front and back of the pouch was approximately 1.2 mm in the longitudinal direction of the heat-sealed portion, as in Examples 1-1, 2, and 3, and was similar to Examples 1-1, 2, and 3. Even without a notch, it could be easily torn from the melt weakened portion.

[Examples 1-7, 8, 9] [Comparative Examples 1, 2, 3]
In the same manner as in Examples 1-1, 2, and 3, three-side heat seal pouches using the laminates 1, 3, and 5 were produced. However, the laser output is continuously output from the roll so that the weakened portion for opening the opening is located at the folded portion 11 of the pouch shown in FIG. 3, that is, overlaps with the folded portion 15 in FIG. It was provided in a band at 80 W. The pouches of Examples 1-7 to 9 had a melt-weakened portion in which about 20 stripe-like orientations were relaxed or eliminated. In addition, the pitch was about 0.3 mm, and the total processing width was 6 mm. In these pouches, even when the contents were filled with liquid soup or the like, there was nothing that broke from the melt-weakened part. The displacement of the center of the fusion weakened portion with respect to the folded portion 11 is about 1.4 mm, and the molten weakened portion sufficiently overlaps with the folded portion 11, and from any part of the folded portion, in a direction crossing the band-shaped molten weakened portion. That is, it could be torn in parallel with the edge heat seal portion 12. In addition, in the pouches of Comparative Examples 1, 2, and 3 made without performing laser processing, the pouches could not be torn from any of the folded portions 11.

[Examples 1-10 to 15]
The laser output was changed every 90 W from 90 W to 140 W, and a three-way heat seal pouch was prepared using the laminate 6 in exactly the same manner as in Examples 1-7, 8, and 9 using the laminates 1, 3, and 5. The laser output and tear initiation were examined. The weakened portion of the pouch thus produced was almost the same stripe shape as in Examples 1-7, 8, and 9. As a result of observation with a scanning electron microscope, from 90 W to 120 W, a melt weakened line having a width of about 150 μm and an unmelted line portion also having a width of about 150 μm were alternately present. Under the conditions of 130 W and 140 W, the width of the melt weakening line was widened and the nylon (PA-2) layer on the surface was foamed as shown in the surface observation A and the cross-sectional observation B (FIG. 20) of the unmelted portion. Under any conditions, as in Examples 1-7, 8, and 9, even if the contents are filled with a liquid soup or the like, nothing breaks from the melt-weakened portion, and tearing starts from anywhere in the folded portion 11. I was able to. Note that the initiation of tearing was better as the laser output was larger, but this is probably due to the promotion of relaxation of the orientation of the nylon layer or foaming.

[Examples 1-16 and 17]
Three-sided heat seal pouches were prepared using the laminates 2 and 4, in exactly the same manner as in Examples 1-7, 8, and 9 using the laminates 1, 3, and 5, respectively. The pouches of Examples 1-16 and 17 had substantially the same stripe-shaped melt-weakened portions as those of Examples 1-7, 8, and 9. Observing the cross section of the melt-weakened portion, in Example 1-17 using the laminate 4, a large amount of foaming was observed in the intermediate nylon (PA-1) layer, and the outer PET layer was as thick as the nylon layer. Not, but foaming was observed. On the other hand, in Example 1-16 using the laminated body 2, the orientation of the outer surface UOPP layer was relaxed, but no foaming was observed. In these pouches, even when the contents were filled with liquid soup or the like, there was nothing that broke from the melt-weakened part. In addition, it could be easily torn from any part of the folded portion 11 in a direction crossing the melt weakened portion.

[Examples 1-18, 19, and 20]
In the same manner as in Examples 1-7, 8, and 9, three-side heat seal pouches using the laminates 1, 3, and 5 were produced. However, the laser processing was performed with a laser output of 100 W using a cylindrical lens as shown in FIG. 9 and positioning the laminate at a focal length of 3.5 inches. The pouches of Examples 1-18, 19 and 20 had a band-shaped melt-weakened portion having a width of 3 mm, and a large number of foams were observed on the surface of the weakened portion. However, there was no portion where the aluminum foil was exposed on the outer surface. In these pouches, even when the contents were filled with liquid soup or the like, there was nothing that broke from the melt-weakened part. Also, the deviation of the center of the melt-weakened portion from the folded portion 11 was about 1.3 mm, and it could be easily torn from any of the folded portions in the direction across the melt-weakened zone. The water content of a single PET film stored under the same conditions as those of the laminates was 0.1% by weight as measured by the method specified by JIS K0068.

[Examples 1-21, 22, 23]
In the same manner as in Examples 1-7, 8, and 9, three-side heat seal pouches using the laminates 1, 3, and 5 were produced. However, the formation of the weakened portion was performed by the infrared lamp condensing method shown in FIG. The infrared lamp used had a power of 500 W, and the parabolic mirror had a focal length of 90 mm and a focused spot of 2 mm. The kaleidoscope used in Examples 1-1, 2, and 3 was used. The pouches of Examples 1-21, 22 and 23 thus prepared had a band-like melt-weakened portion having a width of about 5 mm, and the same effects as those of Examples 1-7, 8 and 9 were obtained. However, no foaming was observed on the surface of the weakened portion.

[Example 1-24]
A three-way heat seal pouch was prepared using the laminate 7 in the same manner as in Examples 1-7, 8, and 9. However, as shown in FIG. 21, a plurality of three-way heat seal pouches were obtained without being cut by the edge heat seal portions 12a and 12c, but were connected. The plurality of pouches formed in this manner can be easily straightened along the edge heat seal portions 12a and 12c from the laser processing portion of the connection portion 9 even if the connection portion 9 is not perforated. Tears and could be split into individual pouches. When the laser processing was not performed, the connecting portion 9 could not be torn. Further, the pouches separated individually could be easily torn from any part of the folded portion 11 in a direction crossing the band-shaped melt-weakened portion.

The packaging bag of the present invention can be used for storing foods and other products.

It is sectional drawing which shows an example of the laminated body suitably used for this invention. It is sectional drawing which shows the other example of the laminated body suitably used for this invention. It is a top view which shows an example (three-side heat seal pouch) of the packaging bag of this invention. It is a top view which shows the other example (four-side heat seal pouch) of the packaging bag of this invention. It is a top view which shows another example (pillow packaging pouch) of the packaging bag of this invention. It is explanatory drawing which shows the surface state of the tear start part by fusion weakening, A is an example in which a tear start part is formed by the solid fusion weakening resin layer, B, B 'is the tear weakening whose tear start part is striped. In the example formed of a resin layer, C indicates an example in which the tear start portion is formed of a dot-shaped melt-weakening resin layer. FIG. 3 is an explanatory diagram showing an example in which a laser beam is condensed by a planoconvex lens and irradiated onto a laminate in a defocused state, according to one embodiment of the present invention. 8 is a graph showing an intensity distribution of a laser beam in the example of FIG. FIG. 13 is an explanatory diagram showing an example in which a laser beam is condensed by a cylindrical lens and irradiated on a laminate under scanning according to another embodiment of the present invention. It is explanatory drawing which shows the example which guide | induces a laser beam to a kaleidoscope and irradiates a laminated body according to another preferable aspect of this invention. It is explanatory drawing for demonstrating the point-like collective beam at the time of using the kaleidoscope which has a square entrance and an exit. FIG. 12 is an explanatory diagram showing a linear beam when scanning is performed using the kaleidoscope of FIG. 11. It is explanatory drawing which shows the dimension relationship of the entrance and exit of a kaleidoscope, and the linear beam formed. FIG. 4 is an explanatory diagram showing a relationship between a mode in which a kaleidoscope is displaced from an optical axis and a point-like aggregate beam formed thereby. It is explanatory drawing which shows several examples of the shape of the entrance of a kaleidoscope. It is a front view which shows an example of the structure | tissue of the molten resin weakening part formed by the method of FIG. It is explanatory drawing which shows the example which irradiates infrared rays to a laminated body using an infrared lamp and a kaleidoscope according to another aspect of the present invention. FIG. 4 is an explanatory view showing an example of using a heat bar according to still another embodiment of the present invention. It is a front view showing an example of a layered product to be attached to bag making. It is the top view and sectional view which copied the result of having observed the foaming of the weakening part in Example 1-14 with a scanning electron microscope. It is a top view showing the three-way heat seal pouch which connected a plurality of pouches created in Example 1-24.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Laminated body 2 Outer layer 3 Intermediate layer 4 Inner layer for heat sealing 5 Second intermediate layer

Claims (7)

At least an outer surface layer and / or an intermediate layer are formed by laminating a laminate made of a thermoplastic resin having molecular orientation, and at least the tear initiation portion or its vicinity is weakened. (1) at least the outer surface resin layer and / or the intermediate resin layer in the vicinity of the tear start portion or in the vicinity thereof are continuously or discontinuously extended in the plane direction over a range in which the width in the direction crossing the opening direction is larger than 1 mm. (2) thermoplastic resin having a moisture content of 0.1% by weight or more according to JIS K 0068, wherein a distributed melt-weakened resin layer is formed, and (2) the outer surface resin layer and / or the intermediate resin layer at or near the tear initiation portion An easily tearable packaging bag, characterized by being a resin and forming a weakened resin layer by foaming. At least an outer surface layer and / or an intermediate layer are formed by laminating a laminate made of a thermoplastic resin having molecular orientation, and at least the tear initiation portion or its vicinity is weakened. (1) Melt weakening in which at least the outer surface resin layer and / or the intermediate resin layer at or near the tear start portion is discontinuously distributed in the plane direction over a range in which the width in the direction crossing the opening direction is larger than 1 mm. A resin layer is formed, (2) the tear start portion or the outer surface resin layer and / or intermediate resin layer in the vicinity thereof is a weakened resin layer due to relaxation or disappearance of molecular orientation, and (3) the tear start The outer surface resin layer and / or the intermediate resin layer in the portion or in the vicinity thereof is composed of a fine dot-shaped or stripe-shaped weakened resin layer arranged almost regularly. Easy-tear resistant packaging bag and features. 3. The easily tearable packaging bag according to claim 2, wherein the dot-shaped or stripe-shaped weakened resin layer has a pitch of 20 to 5000 μm. 4. The easily tearable packaging bag according to claim 1, wherein the weakened resin layer is formed by irradiating a laser beam through a kaleidoscope. (5) The easily tearable packaging bag according to any one of (1) to (4), wherein the outer surface layer or the intermediate layer of the laminate is formed of a polyester, polyamide or olefin resin film stretched in at least one axial direction. (5) The easily tearable packaging bag according to any one of (1) to (4), wherein the laminate is a laminate having a layer structure of thermoplastic polyester / metal foil / olefin resin in order from the surface. 易 The easily tearable packaging bag according to any one of claims 1 to 4, wherein the laminate is a laminate having a layer structure of thermoplastic polyester / nylon / metal foil / olefin resin in order from the surface.

Images