JP3823967B2 - Easy tear packaging bag - Google Patents

Description

  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 are molecularly oriented. In particular, the present invention relates to a packaging bag having easy tearability without substantially damaging the packaging material or the like, and further without reducing the sealing strength or impact strength of the sealing portion.

  In recent years, as a packaging bag for storing foods and other small products, plastic bags or laminated bags made of paper, metal foil, etc., have been widely used. After filling the product, it can be easily sealed by heat sealing, and also has an advantage of excellent airtightness and bag breaking strength.

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

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

  However, in this type of easily tearable packaging bag, the seal width of the notched portion is naturally reduced, and it is inevitable that the strength of this portion of the bag is reduced. Therefore, it is necessary to ensure a sufficiently large seal width at the seal edge portion and to ensure a sufficient remaining width of the seal portion at the notch forming portion. For this reason, there is a problem that the amount of packaging material used increases. Further, it is a problem that notch is generated along with the formation of the notch, and special removal means and monitoring means are required so that the notch is not mixed into the product.

  In order to eliminate the above-mentioned drawbacks 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 small bag formed by three-sided, gluing, and sealing at both ends, a large number of scars are provided substantially densely on the edge line in the fused portion of the sheet constituting the bag. A sealed sachet is described. It is also known to provide a large number of fine holes instead of the scratches.

  Instead of weakening the opening start portion, it is already known that an opening line is formed by a laser or the like in a scheduled tearing portion of the bag. An opening line forming method for a liquid paper container is described in which a carbon dioxide laser is irradiated in a substantially horizontal direction from the surface layer side to the entire upper end side of the section to form an opening line made of a thin groove having a width of about 1 mm. Has been.

  Further, Patent Document 3 below is a packaging bag having heat fusion portions at both end edges, and the respective edges of the tear guide grooves formed at positions corresponding to each other on both the front and back surfaces of the packaging bag, An easily tearable packaging bag is described which is positioned at a distance of about 1 mm or more from the side edge of the heat-sealed portion, and it is also described that the guide groove is formed by a laser.

Japanese Examined Patent Publication No. 61-39228 Japanese Patent Laid-Open No. 62-222835 JP-A-4-327139

  However, the conventional means for forming the weakened portion at the opening start portion or the portion to be cut is often faced with the fact that it is often difficult to balance the strength and easy tearability of the packaging material. That is, the characteristic required for an easy tearing packaging bag is to easily introduce a cut for tearing, but means for weakening the opening start portion with the above-mentioned blade or the like, or means for forming a groove or the like with a laser However, there is a problem that even if the tearability is improved, the stress is concentrated on the weakened portion at the same time, the material strength required for processing and handling is impaired, and the strength against dropping and other impacts is simultaneously reduced. .

  Moreover, in these processing methods, there is a problem that control of processing is very difficult and processing waste is generated. For example, in a processing method using a blade, processing is performed by pressing a blade with a large number of fine and sharp blades or a single blade against the packaging material, but there is a problem in that the cutting thickness varies greatly depending on the pressing force. In order to solve this problem, it is necessary to increase the mechanical accuracy of the processing machine. However, there is a problem that the productivity is lowered and the apparatus cost is increased. Furthermore, due to cutting and wear, there is a problem that many fine powders of the packaging material are generated and mixed into the product.

  Furthermore, in the laser processing method, the laser light is condensed on a spot of about 0.2 mm on the surface of the packaging material by a plano convex lens or the like, and the plastic on the surface of the packaging material is volatilized, thereby forming a groove or a line. However, even if the packaging material position slightly fluctuates up and down, the packaging material may be completely or excessively cut, and in order to make the processing state constant, the accuracy of the processing machine is greatly increased. There is a problem that productivity is lowered and apparatus cost is increased. Further, there is a problem that part of the packaging material sublimes at a high temperature, fumes are generated, and adheres to the packaging material. In order to prevent this, it is necessary to exhaust the fumes.

  The present inventors use a laminate made of a thermoplastic resin in which at least the outer surface layer and / or the intermediate layer are molecularly oriented as a packaging bag, over a range where the width across the opening direction is larger than 1 mm. A laser beam having such an intensity that the outer surface resin layer and / or the intermediate resin layer is melted but does not substantially scatter is irradiated continuously or discontinuously along the surface. It was found that by forming a melt-weakening resin layer, an easily tearable weakened portion free from defects of the conventional method described above can be formed.

  That is, the object of the present invention is to provide easy tearing, that is, easy tearing, without substantially damaging the packaging material and without lowering the seal strength and impact strength of the seal portion. The present invention provides a packaging bag and a manufacturing method thereof.

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

According to the present invention, at least an outer surface layer and / or an intermediate layer are formed by stacking and stacking a laminate made of a thermoplastic resin having molecular orientation, and at least a tear start 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 indefinitely over a range where the width across the opening direction is greater than 1 mm. A melt weakening resin layer continuously distributed in the plane direction is formed , and (2) the water content according to JIS K 0068 is 0.1% in the outer surface resin layer and / or the intermediate resin layer in the vicinity of the tear start portion or its vicinity. There is provided an easily tearable packaging bag characterized by being a thermoplastic resin having a weight percentage of at least or more and forming a weakened resin layer by foaming .

According to the present invention, at least an outer surface layer and / or an intermediate layer is formed by stacking and stacking a laminate made of a thermoplastic resin having molecular orientation, and at least the tear start portion or its vicinity is weakened. In the easily tearable packaging bag, (1) at least the tear start portion or the outer surface resin layer and / or the intermediate resin layer in the vicinity thereof continuously over a range in which the width across the opening direction is larger than 1 mm or Forming a melt-weakening resin layer that is discontinuously distributed in the surface direction; (2) the melt-weakening resin layer has a thickness of the outer surface resin layer and / or the intermediate resin layer substantially reduced by laser beam irradiation; It is one that is formed without has a relaxed to a layer which is weakened by the disappearance of the molecular orientation, and (3) the molten weakened resin layer was substantially regularly arranged Easy-tear packaging bag, characterized in that it is provided in the form of the shape of fine dots like or stripe or solid which is continuous in the plane direction, is provided.
In this case, it is desirable that the dot-like or stripe-like melt weakening resin layer has a pitch of 20 to 5000 μm.

In the easily tearable packaging bag of the above two aspects of the present invention,
1. The weakening resin layer is formed by irradiating a laser beam through a kaleidoscope;
2 . The outer surface layer or intermediate layer of the laminate is composed of a polyester, polyamide or olefin resin film stretched at least in a uniaxial direction.
3 . The laminate is a laminate having a layer configuration of thermoplastic polyester / metal foil / olefin resin in order from the surface;
4 . The laminate is preferably a laminate having a layer structure of thermoplastic polyester / nylon / metal foil / olefin resin in order from the surface.

  According to the present invention, the advantage is that the thermoplastic resin layer is molecularly oriented by forming the molten resin weakening layer using the molecular orientation of the outer surface layer and / or the intermediate layer of the laminate. While maintaining, it is possible to selectively form a weakened portion against tearing with respect to the molten portion.

  Further, for melting by performing melting weakening in the tear starting portion or in the vicinity thereof so that the width in the direction crossing the opening direction is continuously or discontinuously distributed in the plane direction over a range larger than 1 mm. It is possible to disperse the heat over a range wider than 1 mm, thereby avoiding fusing due to local heating and transpiration of the resin. In addition to increasing the tolerance for displacement of the tearing start position, enabling easy tearing and improving easy tearability, and further distributing the stress applied to the melt-weakening resin layer to cause accidental breakage due to impact, etc. It is also possible to prevent the bag. In addition, even if there is a slight deviation between the position of the molten resin weakened layer provided on the laminate on the front side and the position of the molten resin weakened layer provided on the back side, the width is larger than 1 mm, so And can be opened by smooth and reliable tearing.

  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, it is weakened by foaming of moisture in the resin as well as orientational relaxation by melting. And weakening of the resin layer occurs more effectively.

  According to a preferred embodiment of the present invention, when a weak dot-like or stripe-like weakened resin layer arranged almost regularly is formed at least on the outer surface resin layer and / or the intermediate resin layer in the vicinity of the tear start portion, In such a resin melt weakened 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 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 depends on the mechanical strength and resistance of the laminate. This is because impact properties, gas barrier properties, heat resistance, transparency and the like are enhanced. Furthermore, the uniaxial orientation of the thermoplastic resin also has an effect of improving tearability in the orientation direction.

  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 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 the molecular orientation, it is possible to selectively form a weakened portion against tearing with respect to the melted 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 0068, it is weakened by foaming of moisture in the resin as well as orientational relaxation by melting. And weakening of the resin layer occurs more effectively.

  In the present invention, it is also important that the melt weakening in the tear start portion or in the vicinity thereof is performed by continuously or discontinuously distributing in the surface direction over a range where the width across the opening direction is larger than 1 mm. is there. That is, by dissipating heat for melting over a range wider than 1 mm, it becomes possible not only to avoid fusing by local heating and transpiration of the resin, but also tolerability to displacement of the tear start position Can be increased to facilitate tearing to improve easy tearability and further to disperse the stress applied to the melt-weakened resin layer 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 laminate on the front side and the position of the molten resin weakened layer provided on the back side, the width is larger than 1 mm, so And can be opened by smooth and reliable tearing.

  In the present invention, it is particularly preferable that at least the tear starting portion or the outer surface resin layer and / or the intermediate resin layer in the vicinity thereof is composed of a fine dot-like or stripe-like weakening resin layer arranged almost regularly. This is because in such a resin melt weakened 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 a form passing through dots or stripes. In addition, it is preferable that the dot-like or stripe-like weakening resin layer has a pitch of 20 to 5000 μm in order to provide easy tearing without reducing the bag breaking strength.

  Furthermore, it is preferable that the outer surface layer or the intermediate layer of the laminate is made of a film of polyester, polyamide or olefin resin stretched at least in a uniaxial direction. This is because these resins can be easily uniaxially or biaxially oriented, have a great improvement in physical properties due to the orientation, and can easily relax or disappear the orientation due to melting. In addition, polyester and polyamide can be expected to promote weakening due to foaming when melted.

  In the method of the present invention, it is important to form the melt weakened portion by laser irradiation. That is, by irradiating the tear starting portion or the vicinity of the outer surface resin layer and / or the intermediate resin layer with a laser beam over a range in which the width across the opening direction is larger than 1 mm, the outer surface resin layer and / or the intermediate resin layer It is possible to perform heating to such an extent that the resin layer melts but does not substantially scatter, thereby preventing loss of the resin material and without excessive loss of strength of this part. It becomes possible to form an easily tearable weakened resin layer. In the present invention, the tear start portion is generally an opening start portion, but includes a tear start portion that is different from the opening start portion.

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

  Examples of stretched plastic films include 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) film 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) etc. Can be mentioned. These films may be blends or multilayers, and may be uniaxially stretched or biaxially stretched. The thickness is desirably in the range of generally 3 to 50 μm, particularly 5 to 40 μm.

  On the other hand, as heat-sealable resin films, generally, low-, medium-, high-density polyethylene (PE), linear low density polyethylene, isotactic polypropylene (PP), propylene-ethylene copolymer, ethylene-acetic acid Vinyl copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ion-crosslinked olefin copolymers (ionomers), olefin resins graft-modified with ethylenically unsaturated carboxylic acids or their anhydrides, etc. A modified olefinic resin; a polyamide or copolyamide resin having a relatively low melting point to a low softening point; a polyester or copolyester resin having a relatively low melting point to a low softening point; Is done. These films should have a thickness of 15 to 100 μm.

  On the other hand, as the metal foil used for imparting gas barrier properties, various surface-treated steel foils and light metal foils such as aluminum (Al) are used. As surface-treated steel foil, one or more kinds of surface treatment such as galvanization, tin plating, nickel plating, electrolytic chromic acid treatment, chromic acid treatment, etc. applied to cold-rolled steel foil, or prior to final rolling The 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 thermoforming is used. As the most suitable example of the gas barrier resin, there can be mentioned an ethylene-vinyl alcohol copolymer (EVOH). For example, an ethylene-containing resin 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 weight ratio of phenol: water in a mixed solvent. / g or more, especially 0.05
It is desirable to have a viscosity of dL / g or higher.

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

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

  Appropriate examples of laminates are layer structures from the inside to the outside, olefin resin heat seal layer / uniaxially stretched polypropylene film, olefin resin heat seal layer / biaxially stretched nylon film, olefin resin heat seal layer / two layers. 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 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 showing an example of a laminate suitably used in the present invention, this laminate 1 is composed of, in order from the surface, an outer layer 2 made of thermoplastic polyester (PET) / an intermediate layer 3 made of metal foil / an olefin resin. The heat seal inner layer 4 has a layer structure. In FIG. 2, which shows another example of a suitable laminate, this laminate 1 comprises an outer layer 2 made of thermoplastic polyester / second intermediate layer 5 made of nylon / first intermediate layer 3 made of metal foil / olefin. It has the layer structure of the inner layer 4 for heat sealing 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 lowered, and it becomes difficult to selectively form the melt-weakening layer of the outer surface layer and / or the intermediate layer of the laminate in the thickness direction. The flexibility as a bag is lost, and it is difficult to impart tearability.

  The laminate can be produced by any means known per se, such as dry lamination, sandwich lamination, extrusion coating, and coextrusion. When sufficient adhesiveness is not 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 sandwich lamination, any resin is extruded between films or between a film and a resin-coated metal foil. In extrusion coating, any resin is extruded onto a film or metal foil. Done. As the resin to be extruded, 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 copolymers, ethylene-methyl methacrylate copolymers, ion-crosslinked olefin copolymers (ionomers), olefin resins graft-modified with ethylenically unsaturated carboxylic acids or anhydrides; relatively low melting point to low A softening point polyamide or copolyamide resin; a relatively low melting point or low softening point polyester or copolyester resin; a blend resin comprising one or more of the above-described resins and / or a known filler; Layer extrusion or coextrusion is used. An anchoring agent such as urethane or titanate can be applied to the surface to which the extruded resin layer is applied.

[Packaging Bag and Method for Producing the Same] The easy-tearable packaging bag of the present invention is formed by stacking the above laminates so that the heat-sealable resin layers face each other and bag-making them by heat sealing or the like. .

  In FIG. 3 which shows an example (three-way heat seal pouch) of the packaging bag of the present invention, this easily tearable packaging bag 10 has a folded portion 11 on one side and edge heat seal portions 12a, 12b and 12c on three sides. In addition, a melt weakening portion 13 is formed in at least a part of the folded-back portions 11, preferably the three edge heat seal portions 12 a, 12 b, and 12 c. This melt weakening part 13 becomes an opening start part. This type of packaging bag is manufactured by stacking a single laminate and heat-sealing three sides. The heat sealing is performed under a temperature condition in which the heat-sealable resin is melted but the outer surface and / or the molecularly oriented resin layer of the intermediate layer is not substantially melted. 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 which shows the other example (four-way heat seal pouch) of the packaging bag of this invention, this easily tearable packaging bag 10 has edge heat-sealing part 12a, 12b, 12c, 12d in four directions, A melt weakening portion 13 is formed in at least a part of the edge heat seal portions 12a, 12b, 12c, and 12d. This melt weakening portion 13 also becomes an opening start portion.

  In FIG. 5 showing still another example (pillow packaging pouch) of the packaging bag of the present invention, this easy tearing packaging bag 10 is composed of a heat-sealing joint 14 extending in the center by heat sealing, and folded portions on both sides parallel to the joint-pasting. 11a and 11b, and edge heat seal portions 12a and 12b in a direction perpendicular to the palm attachment, and these folded portions 11a and 11b are preferably the palm attachment 14 or the two edge heat seal portions 12a and 12b. A melt weakening portion 13 is formed in at least a part of the above. This melt weakening portion 13 also becomes an opening start portion.

  In the packaging bag of this invention, it is preferable that the heat seal width | variety in an edge heat-sealing part and joint-pasting exists in the range of 3 thru | or 15 mm from a viewpoint of bag breakage prevention and the reduction of the material to be used. In the present invention, by utilizing the fact that the outer surface layer and / or the intermediate layer of the laminate of these heat seal portions maintain the molecular orientation substantially as it is, formation of the melt weakening resin layer, that is, the tear start portion Is possible.

  In the pillow packaging pouch according to the present invention, when the weakened portion 13 is provided along the intersection of the joint-pasting 14 and the edge seal portion 12, the joint-pasting 14 is used as a grip portion, and the pouch device wall along the joint-pasting 14 is torn. As the scheduled portion, it is possible to open along the palm-pasting 14, which is convenient. Further, when the edge seal portion 12 is an easily peelable seal and the second weakened portion 13a is provided in the vicinity of the end portion of the seal portion, the palm attachment 14 serves as a grip portion, and the valley fold portion of the palm attachment 14 By using the tear-off portion 11a in the vicinity of the folded portion 11a, the weakened portion 13 as the opening start portion, and the weakened portion 13a as the tear-starting portion in the vicinity of the folded portion 11a. It is convenient because it can be opened.

[Melt weakening resin layer and its formation]
In the present invention, the melt starting weakness in the tear start portion or in the vicinity thereof is a surface direction continuously or discontinuously over a range where the width across the opening direction is larger than 1 mm, preferably 2 mm to the bag length. It is important that it is carried out in a distributed manner.

  That is, when this width is 1 mm or less, the laminated body is likely to be blown out by local heating and the vaporization of the resin tends to occur, and there is a tendency that smooth tearing becomes difficult due to a slight shift in the tearing start position. Furthermore, stress concentration tends to occur in the melt-weakened resin layer, and the tendency for accidental bag breakage due to impact or the like increases.

  The dimension in the opening direction of the melt weakened part is not particularly limited as long as the tear start part is formed, but it is generally preferably 0.5 mm or more, particularly 2 to 10 mm. If this dimension is too small, it may be difficult to form a tear start sufficient to continue tearing.

Further, the shape of the melt weakening portion may be any shape such as a triangle, a square, a rectangle, a rhombus, a hexagon, a circle, an ellipse, a semicircle, and an indeterminate shape, and its area corresponds to the dimensions described above. In general, it is in the range of 1 to 300 mm ² .

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

The fact that the molecular orientation disappears or relaxes in the melt-weakened part of the outer surface layer and / or intermediate layer of the laminate is known per se, for example, birefringence method, X-ray diffraction method, fluorescence birefringence It can be confirmed by law.

  In the present invention, the melt weakening 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 almost regularly.

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

  In the example of FIG. 6A, the alignment resin layer 21 exists outside the tear start portion 20, but the melt weakening resin layer 13 exists only inside the tear start portion 20, and no alignment resin layer exists. 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 are also present inside the tear start portion 20. And alternately exist. In the example of FIG. 6C, the orientation resin layer 21 exists outside the tear start portion 20, and the melt resin layer 13 is formed in the tear start portion 20 in the sea of the orientation resin layer 21 in the sea. It exists in the state.

  In the present invention, the melt weakening resin layer 13 is preferably present as a large number of dots or stripes at the tear start portion 20, and particularly preferably present as a large number of dots. In such a melt weakened resin layer, as already pointed out, the molecular orientation portion and the melt portion of the thermoplastic resin coexist and the advantages of both are achieved in combination.

  In addition, the melt weakening resin layer has a pitch of 20 to 5000 μm, particularly 50 to 2000 μm, regardless of the ratio of the dot-like or stripe-like melt weakening resin layer and the unmelted portion, thereby reducing the bag breaking strength. It is preferable in order to impart easy tearability. The dot diameter or stripe width is preferably in the range of 20 to 5000 μm, particularly 50 to 2000 μm.

  In the present invention, the formation of the melt weakened portion is not particularly limited, but it is preferably formed by laser irradiation. That is, by irradiating the tear starting portion or the vicinity of the outer surface resin layer and / or the intermediate resin layer with a laser beam over a range in which the width across the opening direction is larger than 1 mm, the outer surface resin layer and / or the intermediate resin layer It is possible to perform heating to such an extent that the resin layer melts but does not substantially scatter, thereby preventing loss of the resin material and without excessive loss of strength of this part. It becomes possible to form an easily tearable weakened resin layer.

  In the present invention, the molten resin layer may be in an amorphous state or a low crystallized state, or may be in a thermally crystallized state. A limited portion of the oriented and crystallized resin from the surface to the middle in the thickness direction is rapidly heated to a temperature higher than the melting point within a short time and rapidly cooled to a temperature lower than the crystallization temperature when heating is stopped. As a result, the molten resin layer becomes amorphous or low crystallized. In such an amorphous or low-crystallized state, the impact resistance of the processed part is maintained at a high level. On the other hand, when the time for the molten resin layer to pass through the crystallization temperature region is long, the molten resin layer tends to be thermally crystallized. 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, as in the case of hot filling or retort sterilization. When the molten resin is thermally crystallized, it becomes somewhat brittle as a property and brings 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, and in this case, the output of the laser beam and irradiation time or scanning speed are changed. Thus, the thickness and temperature of the molten layer can be controlled. Further, the width can be controlled by changing the laser beam diameter. The laser output is appropriately selected depending on the type of the constituent substrate and the material of the ink layer. Conversely, when 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 collected by a plano-convex lens (a lens having one flat surface and the other surface is convex), and is irradiated in a defocused state on the laminate. If necessary, scanning irradiation is performed in order to secure a predetermined irradiation area.

In FIG. 7 for explaining this aspect, the laser beam 30 is condensed by a plano-convex lens 31 (flat surface 32, convex surface 33) and defocused on the laminate 1, that is, from the focus distance f. Further, irradiation is performed with only the defocus distance f ₀ being made.

Considering the case of irradiating a laser beam normally, it is normal to focus on the position of the laminate (f). In this case, the intensity distribution of the laser beam is a steep Gaussian as shown by the curve a in FIG. Distribution. Therefore, the width is narrow (half-value width H ₀ ), the strength at the center is high, and the surface temperature of the laminate becomes high. On the other hand, in this invention, as shown in FIG. 7, a focus position is shifted (defocused) and it irradiates to a laminated body. By doing so, the intensity distribution of the laser beam becomes a smooth Gaussian distribution (half-value width H ₁ , H ₁ >> H ₀ ) as shown by a curve b in FIG. Therefore, the central portion does not become high temperature, no fume is generated, and a wide weakened portion is processed. As the condensing lens, a known lens such as a meniscus lens, a non-curved surface lens, a double-sided convex lens can be arbitrarily used in addition to a plano-convex lens.

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

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

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

  In FIG. 10 for explaining the kaleidoscope, this kaleidoscope 36 is a metal rectangular parallelepiped cylinder, a hole 37 having various shapes in the vicinity of the center is opened, and the inner surface 38 has a high reflectivity. Gold plating etc. are given. The light overlaps at the portion where the wavelength of the laser light reflected by the inner surface 38 is shifted by an integral multiple, and the light is canceled out at the portion where the wavelength is shifted by half wavelength, so that a fine interference pattern 40 is formed.

  When the laser beam 30 is condensed on the cavity entrance 37 of the kaleidoscope 36 by the plano-convex 31, the laser beam at the exit of the kaleidoscope 36 has a square cross section as shown in FIG. A point-like aggregate beam. By scanning this beam, a large number of striped scanning beams as shown in FIG. 12 are formed. Thereby, the strength of the packaging material is not reduced and the tearability is not reduced.

  In the pointed aggregate beam from the kaleidoscope, the interval and size of each point is the distance from the exit of the kaleidoscope to the laminate (the distance increases and the strength decreases, but the cross-section increases) Varies depending on the dimensions of the kaleidoscope.

  It is also possible to change the size of the entrance and exit of the cavity portion of the kaleidoscope, which has the advantage that a very large weakened portion can be processed. 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 pointed aggregate beam is about 5 mm × 20 mm. . Further, the pattern of the point-like collective beam is as shown in FIG.

  Further, when the kaleidoscope is tilted from the optical axis of the plano-convex lens as shown in FIG. 14A, as shown in FIG.

  Furthermore, as shown in FIG. 15, the shape of the entrance 37 of the cavity portion of the calloscope can be a triangle, a hexagon, or the like in addition to the quadrangle. In this case, if the hollow portion is a triangular prism or hexagonal prism, a triangular or hexagonal resin melt weakened portion interspersed with a large number of dot-shaped resin melted portions can be obtained.

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

  In the present invention, a carbon dioxide laser is used as the laser beam. In general, the output is preferably in the range of 10 W to 1.2 kW, but of course not limited thereto.

  In the present invention, an infrared lamp or a hot plate can be used as the heat source in addition to 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. . Thereby, an infrared beam 47 having a substantially square area as shown in FIG. 17B can be formed.

  The processing method using a laser beam or an infrared lamp can process the laminated body without contact, so the application is very simple. However, when using a hot plate, the position to be processed in the weakened part of the laminated material In addition, 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 to the processed surface of the laminate, such as a polytetrafluoroethylene coating, is desirable. A cartridge heater 52 is incorporated in the main body of the heat bar 50, the temperature is detected by a thermocouple 53 inserted therein, the power supplied to the heater 52 is adjusted, and the tip temperature of the heat bar is 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.

  In the present invention, the weakened layer can be formed by melting the resin before bag making, during bag making, or after bag making. For example, a laser beam or an infrared beam is irradiated to a molecular orientation film to be an arbitrary stage for manufacturing a laminate, that is, a surface layer before lamination, during lamination, or after lamination, or an intermediate layer. A melt weakened portion of the pattern can be formed.

  In FIG. 19 which shows an example of the laminated body which should be attached | subjected to bag making, this laminated body 1 has the part 15 which should be folded | backed by the sheet | seat parts 17a and 17b which oppose, and three parts 16a, 16b and 16c which should be heat-sealed The melt weakening layer 13 is formed at the edge of the upper sealing portion 16b of both the sheet portions 17a and 17b. In this case, since the melt weakening layer 13 is formed over a width of 1 mm or more, the distance L1 from the portion 15 to be folded back to the melt weakening layer 13 of one sheet 17a and the other sheet 17b from the portion 15 to be folded back. The distance L2 to the melt weakening layer 13 does not exactly coincide with each other, and even if there is some deviation between them, the packaging bag can be torn and opened smoothly.

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

  The invention is illustrated in 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 adhesion interface by sandwich lamination, and the PET / Al adhesion surface is coated with a urethane anchor as required. Further, the symbol “·” in the table indicates an adhesive interface dry-laminated using a urethane-based adhesive.
Note 2) The numbers 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 mirror P-60) with a laminate surface printed.
PA-1: Biaxially stretched nylon 6 film (Unitika Emblem RT).
PA-2: Biaxially stretched nylon 6 film (Kojin Bonil RX) with printing on the laminate surface.
Al: Aluminum foil.
EVOH: Biaxially stretched ethylene vinyl alcohol copolymer film (Kuraray EF-XL).
UOPP: Rolled uniaxially stretched polypropylene film (Nisshi Barilla PG) with printing on the laminate surface.
CPP: Polypropylene cast film.
LDPE: Low density polyethylene layer for extrusion coating.
LLDPE: Linear low density polyethylene film.
HDPE: High-density polyethylene laterally stretched film (Toyo Kagaku Karaliyan Y).

[Examples 1-1, 2, and 3 and Comparative Examples 1, 2, and 3]
Using the laminates 1, 3, and 5 having a width of 100 mm, a pouch having a weakening portion for opening initiation at the edge heat seal portions 12a and 12c having a width of 4 mm of the three-way heat seal pouch shown in FIG. Created using. In addition, the weakening part unwinded the laminated body intermittently using the photoelectric mark from the roll, and processed it into the PET surface of the outer layer with the laser. As shown in FIG. 19, the processing places were provided at two places so as to be located at the same position on the front and back of the pouch when folded at the folded portion 15 of the laminate 1. As shown in FIG. 14, the carbon dioxide laser beam was converted into a point-like collective beam with a kaleidoscope through a planoconvex as shown in FIG. 14 and the laser output was 60 W and the irradiation time was 60 msec. The focal length of the plano convex lens was 2.5 inches, the length of the kaleidoscope was 138 mm, the entrance to the cavity was a 3 mm × 6 mm rectangle, and the exit was a 6 mm × 6 mm rectangle. 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 created in this way have a large number of dot-like weakened portions, and have a pitch of about 0.3 mm, 6 mm in the longitudinal direction of the heat seal portion, and 3 mm in the width direction. It was scattered in 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 disappeared. None of these pouches broke from the melt-weakened part even when the contents were filled with liquid soup or the like. In addition, the melt weakened portion between the front and back of the pouch is approximately 1.2 mm in the longitudinal direction of the edge heat seal portion 12, and the melt weakened portion can be easily torn without a notch from the portion where the melt weakened portion overlaps the front and back. I was able to. Similarly, in the pouches of Comparative Examples 1, 2, and 3 that were prepared using the laminates 1, 3, and 5 without being subjected to laser processing, they could not be torn from the edge heat seal part 12.

[Comparative Examples 4, 5, 6]
In the same manner as in Examples 1-1, 2, and 3, a three-way heat seal pouch having a weakening portion for opening initiation using the laminates 1, 3, and 5 was prepared. However, the weakened part continuously unwound the laminate from the roll, and processed it intermittently with a laser at a fixed position on the PET surface of the outer layer using a photoelectric mark. The laser processing was performed by condensing a carbon dioxide laser beam with a plano-convex lens, positioning the laminate at a focal length of approximately 2.5 inches, and a laser output of 3 W and an irradiation time of about 60 msec. During processing, the outer surface PET layer sublimated, a large amount of fume was generated, and the lens became dirty. When the weakened portion was observed, the PET layer was completely removed, and the length was 3 mm and the 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 liquid soup or the like, in Comparative Example 5 using the laminate 3, the remaining base material in the weakened portion was thin, so that there was a bag breakage in a conveyance test or the like. Moreover, although the shift | offset | difference of the weakening part in the front and back of a pouch was about 1.2 mm in the longitudinal direction of the edge heat seal part 12 similarly to Examples 1-1, 2, and 3, the base material is in a process part. In Comparative Examples 4 and 6 using the laminates 1 and 5 that remained thick, they could not be easily torn.

[Examples 1-4, 5, 6]
Similar to Comparative Examples 4, 5, and 6, a three-way heat seal pouch having a weakening portion for opening initiation using the laminates 1, 3, and 5 was prepared. However, the laminated body was processed at a laser output of 75 W at a position defocused 12 mm downward from the focal point. In Examples 1-4, 5 and 6, no fume was generated during processing, and the outer PET layer was melted and not sublimated. In the weakened portion, the orientation of the outer surface PET layer was relaxed or disappeared. The length of the melt weakened portion was 3 mm and the width was about 1.1 mm. None of these pouches broke from the melt-weakened part even when the contents were filled with liquid soup or the like. Further, 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 heat seal portion as in Examples 1-1, 2 and 3, and the same as in Examples 1-1, 2 and 3. Even if there was no notch, it could be easily torn from the melt weakened part.

[Examples 1-7, 8, 9] [Comparative Examples 1, 2, 3]
In the same manner as in Examples 1-1, 2, and 3, three-way heat seal pouches using laminates 1, 3, and 5 were prepared. However, the laser output is performed while continuously unwinding the laminate from the roll so that the opening-start weakening portion is positioned at the folded-back portion 11 of the pouch shown in FIG. 3, that is, the folded portion 15 in FIG. It was provided in a strip shape at 80W. The pouches of Examples 1-7 to 9 had a melt weakened portion in which approximately 20 stripe-like orientations were relaxed or disappeared. The pitch was about 0.3 mm, and the total processing width was 6 mm. None of these pouches broke from the melt-weakened part even when the contents were filled with liquid soup or the like. Further, the deviation of the center of the melt weakened portion with respect to the folded portion 11 is about 1.4 mm, and the melt weakened portion sufficiently overlaps the folded portion 11, so that the melt-weakened portion crosses the belt-shaped melt weakened portion from anywhere in the folded portion. That is, it was able to tear in parallel with the edge heat seal part 12. In addition, in the pouches of Comparative Examples 1, 2, and 3 prepared without performing laser processing, it was not possible to tear from anywhere in the folded portion 11.

[Examples 1-10 to 15]
The laser output was changed every 10 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 power and tear initiation were investigated. The weakened part of the pouch produced in this way was almost the same stripe shape as in Examples 1-7, 8, and 9. As a result of observation with a scanning electron microscope, a melt weakening line having a width of about 150 μm and an unmelted line portion having a thickness of about 150 μm were alternately present from 90 W to 120 W. Under the conditions of 130 W and 140 W, the width of the melt weakening line widened and the surface 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 condition, as in Examples 1-7, 8, and 9, there is no breakage from the melt weakening part even if the contents are filled with liquid soup or the like, and tearing starts from anywhere in the folded part 11 I was able to. The initiation of tearing was more excellent as the laser output was larger. This is considered to be due to the promotion of orientation relaxation or foaming of the nylon layer.

[Examples 1-16, 17]
Three-way heat seal pouches were prepared using laminates 2 and 4 in exactly the same manner as in Examples 1-7, 8 and 9 using laminates 1, 3 and 5. The pouches of Examples 1-16 and 17 had stripe-like melt weakening portions almost the same as those of Examples 1-7, 8, and 9. When 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 large as the nylon layer. Although not, foaming was observed. On the other hand, in Example 1-16 using the laminate 2, although the orientation relaxation of the outer surface UOPP layer was observed, no foaming was observed. None of these pouches broke from the melt-weakened part even when the contents were filled with liquid soup or the like. Moreover, it could be easily torn from anywhere in the folded portion 11 in the direction crossing the melt weakened portion.

[Examples 1-18, 19, 20]
Similar to Examples 1-7, 8, and 9, three-way heat seal pouches using laminates 1, 3, and 5 were prepared. However, in the laser processing, as shown in FIG. 9, a cylindrical lens was used, and the laminate was processed at a laser output of 100 W with 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. None of these pouches broke from the melt-weakened part even when the contents were filled with liquid soup or the like. Further, the center shift of the melt weakened portion with respect to the folded portion 11 was about 1.3 mm, and it could be easily torn from anywhere in the folded portion in the direction across the melt weakened zone. In addition, the water content measured by the method prescribed | regulated by JISK 0068 of the single-piece | unit PET film stored on the same conditions as these laminated bodies was 0.1 weight%.

[Examples 1-21, 22, 23]
Similar to Examples 1-7, 8, and 9, three-way heat seal pouches using laminates 1, 3, and 5 were prepared. However, the weakened portion was formed by the infrared lamp condensing method shown in FIG. The infrared lamp used was 500 W, the focal length of the parabolic mirror was 90 mm, and the focused spot was 2 mm. In addition, the kaleidoscope used in Examples 1-1, 2 and 3 was used. The pouches of Examples 1-21, 22 and 23 created in this way had a belt-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 connected without being cut at the edge heat seal portions 12a and 12c. The plurality of pouches created in this way can be straight along the edge heat seal portions 12a and 12c easily from the laser processing portion of the connecting portion 9 even if the connecting portion 9 is not perforated. Torn and could be divided into individual pouches. In addition, when the laser processing was not performed, the connection part 9 could not be torn. Moreover, the pouches separated individually could be easily torn from anywhere in the folded-back portion 11 in the direction crossing the belt-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 used suitably for this invention. It is sectional drawing which shows the other example of the laminated body used suitably for this invention. It is a top view which shows an example (three-way heat seal pouch) of the packaging bag of this invention. It is a top view which shows the other example (four-way heat seal pouch) of the packaging bag of this invention. It is a top view which shows other 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 melt weakening, Comprising: A is an example in which the tear start part is formed of a solid melt weakening resin layer, B and B 'are melt weakenings in which the tear start part is a stripe shape The example formed with the resin layer, C shows the example where the tear start part is formed with a dot-like melt weakening resin layer. It is explanatory drawing which shows the example which condenses a laser beam with a plano convex lens according to one aspect of this invention, and irradiates in the defocused state to a laminated body. It is a graph which shows the intensity distribution of the laser beam in the example of FIG. It is explanatory drawing which shows the example which condenses a laser beam with a cylindrical lens and irradiates a laminated body under scanning according to the other aspect of this 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 the further another suitable 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 exit. It is explanatory drawing which shows a linear beam at the time of scanning using the kaleidoscope of FIG. It is explanatory drawing which shows the dimensional relationship of the entrance and exit of a kaleidoscope, and the linear beam formed. It is explanatory drawing which shows the relationship between the aspect which disposes a kaleidoscope from the optical axis, and the dotted | punctate aggregate beam formed by this. 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 this invention. It is explanatory drawing which shows the example which uses a heat bar according to another aspect of this invention. It is a front view which shows an example of the laminated body which should be attached | subjected to bag making. It is the top view and sectional drawing which copied the result of having observed the foaming of the weakening part in Example 1-14 with the scanning electron microscope. It is a top view which shows the three-way heat seal pouch which connected the some pouch created in Example 1-24.

Explanation of symbols

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

Claims (7)

  An easily tearable packaging bag formed by stacking a laminate made of a thermoplastic resin in which at least an outer surface layer and / or an intermediate layer are molecularly oriented, and having at least a tear start portion or its vicinity weakened (1) At least the tear start part or the outer surface resin layer and / or the intermediate resin layer in the vicinity thereof in the surface direction continuously or discontinuously over a range where the width across the opening direction is larger than 1 mm. (2) Thermoplastic having a moisture content of 0.1% by weight or more according to JIS K 0068, wherein a distributed melt weakening resin layer is formed, and (2) the outer surface resin layer and / or the intermediate resin layer in the vicinity of the tear start portion An easily tearable packaging bag which is a resin and has a weakened resin layer by foaming. An easily tearable packaging bag formed by stacking a laminate made of a thermoplastic resin in which at least an outer surface layer and / or an intermediate layer are molecularly oriented, and having at least a tear start portion or its vicinity weakened (1) Melting weakening in which at least the outer surface resin layer and / or the intermediate resin layer in the vicinity of the tear start portion or its vicinity are discontinuously distributed in the surface direction over a range in which the width across the opening direction is larger than 1 mm. (2) The melt weakening resin layer is formed without substantially reducing the thickness of the outer surface resin layer and / or the intermediate resin layer by irradiation with a laser beam, and the molecular orientation form of relaxation or has a weakened layer by the disappearance, and (3) the molten weakened resin layer, a fine dot-like or stripe which is substantially regularly arranged Or an easy tearable packaging bag, characterized in that it is provided a solid shape in the surface direction continuous.   The easily tearable packaging bag according to claim 2, wherein the dot-like or stripe-like melt weakening resin layer has a pitch of 20 to 5000 µm.   The easily tearable packaging bag according to any one of claims 1 to 3, wherein the melt-weakening resin layer is formed by irradiating a laser beam through a kaleidoscope.   The easily tearable packaging bag according to any one of claims 1 to 4, wherein an outer surface layer or an intermediate layer of the laminate is formed of a film of polyester, polyamide, or olefin resin stretched at least in a uniaxial direction.   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 / metal foil / olefin resin in order from the surface. 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