JP2004136980A - Easily tearable packaging bag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging bag having easy-to-tear property without using a special material, without substantially generating damage, abrasion and the like and without reducing a sealing strength, an impact resistant strength and the like of a seal portion. <P>SOLUTION: The packaging bag is formed by laminating laminates in each of which at least an outer surface layer and/or an intermediate layer are made of a molecular oriented synthetic resin, and linear portions to be torn of the upper sheet and the lower sheet are at least partly weakened. The outer surface resin layer and/or the intermediate resin layer of the linear portion to be torn form a transversely continuous or discontinuous molten weakened resin layer having width of larger than 1mm in a transverse direction of a tearing direction. The weakened resin layer of the outer surface resin layer and/or the intermediate resin layer is made by foaming a thermoplastic resin containing not less than 0.1 wt.% of water according to Japanese Industrial Standards K0068. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an easily tearable packaging bag and a method for producing the same, and more particularly, to form a bag by laminating a laminate made of a thermoplastic resin in which at least an outer surface layer and / or an intermediate layer is molecularly oriented. In the packaging bag formed by the above, imparting easy tearing property or easy opening property without substantially causing abrasion of the packaging material or the like, and further without reducing the sealing strength or the impact strength of the sealing portion. And a method for producing the same.

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.

プ ラ ス チ ッ ク However, the plastic film has a high tear strength, and there is a problem that it is often difficult to tear by hand when taking out the contents. Also, the tear is split in different directions on the front and back of the bag, resulting in a so-called tear-like shape, which cannot be completely torn. Alternatively, there is a problem that the contents protrude when the tear is increased.

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 uses a laminated sheet in which a uniaxially stretched film provided with molecular orientation is bonded so that the molecular orientation direction and the tearing direction of the bag coincide with each other. It utilizes the property that the stretched film is easily torn in the stretching direction.

The easy-opening packaging bag using the laminated sheet has no problem in terms of bag breaking strength and easy tearing property, but simply imparts easy tearing property to the linear tearing scheduled portion, and the entire surface of the bag making sheet is used. It was necessary to attach a uniaxially oriented film to the film, so that the cost of the easily-openable packaging bag was increased, and valuable resources were wasted. Also, the tear was limited to a straight one.

易 Easy-open packaging bags for retort foods are very common today, but with their spread, there is a strict demand for material saving and cost reduction.

It is already known that an opening line is formed by a laser or the like at a portion to be cut of a bag by laser or the like. A method of forming an opening line for a liquid paper container, which comprises irradiating a carbon dioxide gas laser in a substantially horizontal direction over the entire circumference of the container to form an opening line formed of a thin groove having a width of 1 mm or less.

Patent Document 2 below discloses a packaging bag having heat-sealed portions at both end edges, wherein each edge 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 easy-open packaging bag which is 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 laser.

JP-A-62-222835 JP-A-4-327139

However, with the conventional means for forming the weakened portion in the portion to be torn, it is often difficult to achieve a good balance between the strength of the packaging material and the ease of tearing. That is, the property required for the easily tearable packaging bag is to correctly guide the tear along the linear tearing scheduled portion, but in the means for forming a groove or the like by the laser described above, the tearability is improved. However, at the same time, there is a problem that the stress is concentrated on the weakened portion, and the strength against a drop or other impact is also reduced at the same time.

In the processing method using a laser, a laser beam is condensed by a plano convex lens or the like on a spot of about 0.2 mm on the surface of the packaging material to volatilize the plastic on the surface of the packaging material, 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. Further, even if the narrow grooves on the front and back of the bag are slightly displaced, tearing becomes difficult, and tears may be dislodged from the narrow grooves. Further, in the case of a laminate using a metal foil, there is a problem that the foil is exposed and the corrosion resistance on the outer surface side is significantly impaired. Further, in the case of providing a thin score-shaped groove, this portion is easily bent locally, and there is a problem that the foil is fatigued and broken linearly during distribution.

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 tear direction is larger than 1 mm. The outer surface resin layer and / or the intermediate resin layer is continuously irradiated along the linear tearing portion with a laser beam having an intensity enough to melt but not substantially scatter the resin layer, thereby irradiating the irradiated portion. It has been found that by forming the melt-weakened resin layer, it is possible to form the easily tearable weakened portion without the defect of the conventional method described above.

That is, the object of the present invention is to use a special material for imparting easy tearing property, and to substantially reduce wear and the like of the packaging material, and further to improve the sealing strength and impact strength of the sealing portion. An object of the present invention is to provide a packaging bag provided with easy tearing, that is, easy opening without lowering, and a method for producing the same.

Another object of the present invention is to provide a method of manufacturing an easily tearable packaging bag which can easily impart tear resistance 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 are formed into a bag. Wherein the outer surface resin layer and / or the intermediate resin layer of the portion to be linearly torn is over a range in which the width in the direction transverse to the tearing direction is larger than 1 mm. An easily tearable packaging bag, wherein a melt-weakening resin layer is formed continuously in the transverse direction or intermittently in the transverse direction.

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 and formed into a bag, and the weakened portion is formed at an arbitrary stage of bag production at a portion to be linearly torn. In a method of forming a bag, the outer surface resin layer and / or the intermediate resin layer of the portion to be linearly torn at an arbitrary stage in the production of the bag, the width of the outer surface resin layer and / or the intermediate resin layer in the direction transverse to the torn tearing direction is larger than 1 mm. A laser beam having an intensity that causes melting of the surface resin layer and / or the intermediate resin layer but does not substantially scatter the laser beam is continuously or intermittently applied in the transverse direction, and the laser beam is irradiated in the intended tearing direction. Scanning, thereby forming a linear melt-weakened resin layer on the irradiated portion.

In the easily tearable packaging bag of the present invention,
1. That the outer surface resin layer and / or the intermediate resin layer at the linear tear initiation portion is a weakened resin layer due to relaxation or disappearance of molecular orientation;
2. In some cases, in addition to this, the outer surface resin layer and / or the intermediate resin layer at the portion to be linearly torn may be JIS
A thermoplastic resin having a moisture content of 0.1% by weight or more according to K0068, and a weakened resin layer formed by foaming;
3. The outer surface resin layer and / or the intermediate resin layer of the portion to be linearly torn is composed of a finely striped weakened resin layer arranged substantially regularly;
4. The striped 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 where the width in the direction crossing the tearing direction is larger than 1 mm. It is preferably formed by irradiating continuously or discontinuously along the surface.

Further, 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 melt weakening of the linear tear portion or the vicinity thereof is performed so that the width in the direction crossing the tear direction is larger than 1 mm, and is continuously or discontinuously distributed in the plane direction. 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 deviation of the tearing 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 smooth and reliable tearing is 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, a weakly dotted resin or stripe-like weakened resin layer is formed in at least the outer surface resin layer and / or the intermediate resin layer at or near the linear tear portion. In such a resin weakened layer, the molecular orientation part and the molten part 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 a state where the thermoplastic resin layer is molecularly oriented, particularly in a biaxially oriented state, the tear 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, and By relaxing or eliminating the molecular orientation, it is 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 K0068, the orientation is reduced by melting, and the weakening due to foaming of moisture in the resin is also achieved. This weakens the resin layer more effectively.

溶 融 It is also important that the melt weakening of the portion to be linearly torn in the present invention is continuously distributed over a range in which the width in the direction crossing the tearing direction is larger than 1 mm. In other words, by dispersing the heat for melting over a range wider than 1 mm, it is possible not only to prevent the resin layer from being melted or evacuated and dissipated due to local heating, but also to enable smooth tearing. To improve the easy tearing property. Further, the stress applied to the melt-weakened resin layer can be 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 smooth and reliable tearing is possible.

に お い て In the present invention, it is particularly preferable that at least the outer surface resin layer and / or the intermediate resin layer at the portion to be linearly torn is formed of a finely striped weakened resin layer 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 a stripe-shaped fusion zone. Further, it is preferable that the striped weakened resin layer has a pitch of 20 to 5000 μm in order to impart easy tearability without reducing the bag breaking strength.

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 polyamide or polyester, promotion of weakening due to foaming at the time of 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 of the portion to be linearly torn over a range where the width in the direction crossing the tearing direction is larger than 1 mm, the outer surface resin layer and / or the intermediate resin layer is irradiated. Heating can be performed to such an extent that the layer melts but does not substantially cause its scattering, thereby preventing loss of the resin material and without excessively reducing the strength of this portion. It becomes possible to form an easily tearable melt-weakened resin layer. The portion to be torn in the present invention is not limited to a portion that is torn for opening, but also includes, for example, a portion that is torn to divide a connecting bag formed by heat sealing a plurality of small bags into individual small bags.

[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 (LLDPE), linear ultra-low-density polyethylene (LVLDPE), and isotactic polypropylene ( i-PP), syndiotactic polypropylene (s-PP), propylene-ethylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ion-crosslinked olefin Modified olefin resins such as copolymers (ionomers), olefin resins graft-modified with ethylenically unsaturated carboxylic acids or anhydrides; polyamides or copolyamide resins having a relatively low melting point or low softening point; relatively low melting points Or a polyester or copolyester resin having a low softening point; Or those of two or more thereof are used. 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 or more, especially 1.5
It is desirable that this is the case.

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 its manufacturing method] The easily tearable packaging bag of the present invention is formed by stacking the above-mentioned laminate 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. are doing. Along the folded portion 11 or any one of the three edge heat seal portions 12a, 12b, and 12c, a linear tearing scheduled portion 13 including a melt-weakened portion having a width of at least 1 mm is formed. Notches or other tear initiation portions 14 which are not generally required, but are known per se, may be provided at one end of the linear tear portion 13. It is to be understood that although only those of the top sheet with linear tear portions 13 are shown, similar linear tear portions 14 are also formed on the bottom sheet. By starting the tearing from one end of the linear tearing scheduled portion 13, the tearing proceeds stably while being guided by the linear tearing scheduled portion 13. 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 molecularly oriented resin layer of the outer surface layer and / or 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 (four-side heat seal pouch) of the packaging bag of the present invention, this easy-open packaging bag 10 has edge heat seal portions 12a, 12b, 12c, and 12d on four sides, and A linear tear to be formed at a small distance from and along the inner edge of any one of the edge heat-sealed portions 12a, 12b, 12c, 12d, comprising a melt-weakened portion having a width of at least 1 mm. The part 13 is formed. The initiation and progress of the tear is the same as in FIG.

In FIG. 5, which shows still another example (pillow packaging pouch) of the packaging bag of the present invention, this easily-openable packaging bag 10 has a palm joint 15 extending to the center by heat sealing, and folded portions on both sides parallel to the joint palm. 11a and 11b, and edge heat seal portions 12a and 12b in a direction perpendicular to the jointed palm. A linear tear consisting of a melt-weakened portion of 1 mm or more is provided at a small distance from and along the folded portion 11, the palm joint 15 or the two edge heat seal portions 12a and 12b. A part 13 is provided.

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, the formation of a melt-weakened resin layer, that is, linear tearing, is performed by utilizing the fact that the outer surface layer and / or the intermediate layer of these heat-sealed laminates maintain the molecular orientation substantially intact. This enables the formation of the scheduled portion.

In the pillow packaging pouch of the present invention, when a pair of linear tearing scheduled portions 13 and 13 is provided along the base of the palm joint 14, the tear is guided along the palm joint 15, and the tear is guided along the joint palm 15. This is convenient because opening along the paste 14 becomes possible.

[Melt-Weakened Resin Layer and Formation Thereof] In the present invention, the melt-weakening of the portion to be linearly torn is performed over a range where the width in a direction crossing the tearing direction is larger than 1 mm, preferably 2 to 10 mm. is important.

That is, when the width is 1 mm or less, melting of the laminated body due to local heating and evaporation of the resin 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.

The dimension of the melt-weakened portion in the tearing direction is generally provided over the entire length in the tearing direction, but is provided in a range where the tearing is substantially performed, for example, partially provided over about one-tenth of the total length. Is also good.

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 stripes arranged almost regularly. Further, it may be provided in a minute dot shape which is arranged substantially regularly.

In FIG. 6 showing a cross section (cross section in the width direction) of a portion to be linearly torn due to melt weakening, A shows an example in which the torn linear tear portion 13 is formed of a solid melt-weakened resin layer 20; Shows an example in which the linear tearing scheduled portion 13 is formed by a large number of fine stripe-shaped melt-weakening resin layers 20a. When the resin is melted, the stress applied to the resin is relaxed and the surface is distorted.

In the example of FIG. 6A, the alignment resin layer 21 exists outside the solid melt-weakened resin layer 20, but only the melt-weakened resin layer 20 exists inside the linear tearing scheduled portion 13 and the alignment resin layer 20 There are no layers. In the example of FIG. 6B, the alignment resin layer 21 exists outside the linear tearing scheduled portion 13, and the stripe-shaped melt-weakening resin layer 20 a and the striped melting weakened resin layer 20 a also exist inside the linear tearing scheduled portion 13. The alignment resin layer 21 is alternately repeated.

に お い て In the present invention, it is preferable that the melt-weakening resin layer 20 exists as a large number of stripes in the linear tearing scheduled portion 13. It has already been pointed out that 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. Further, in this case, even if the tearing deviates from one stripe, the tearing is carried out to the next stripe, so that there is an advantage that the tearing is excellent in guiding property.

Also, the stripe-shaped melt-weakened resin layer has a pitch of 20 to 5000 μm, especially 50 to 2000 μm, regardless of the ratio of the melt-weakened resin layer to the unmelted portion, without reducing the bag breaking strength. It is preferable for imparting easy tearability. Further, the width of the stripe is preferably in the range of 10 to 5000 μm, particularly 30 to 2000 μm.

で は In the present invention, the formation of the melt weakened portion is preferably performed by laser irradiation. That is, by performing laser irradiation on the outer surface resin layer and / or the intermediate resin layer of the portion to be linearly torn over a range where the width in the direction crossing the tearing direction is larger than 1 mm, the outer surface resin layer and / or the intermediate resin layer is irradiated. Heating can be performed to such an extent that the layer melts but does not substantially cause its scattering, thereby preventing loss of the resin material and without excessively reducing the strength of this portion. It becomes 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, linear or curved scanning irradiation of a carbon dioxide laser beam can be used.In this case, by changing the output and scanning speed of the laser beam, 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. Of course, scanning irradiation is performed in order to secure a predetermined length of the predetermined linear tearing portion.

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 further performed with the defocus distance f ₀ .

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 menikas lens, a non-curved lens, or a biconvex lens can be used as necessary, in addition to a 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 width of 1 mm or more and having a solid shape can be machined. Of course, if the light is irradiated through one or several masking skets parallel to the scanning direction, several stripe-shaped weakened portions can be processed.

In the most preferred embodiment of the present invention, the laminated body is irradiated with a laser beam through a kaleidoscope (tubular optical interference system). Of course, scanning irradiation is performed in order to secure the required length of the portion to be linearly torn.

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. Thereby, the strength of the packaging material does not decrease, and the tearability does not decrease.

That is, as shown in the Examples and Comparative Examples, a nylon (15 μm) / linear low-density polyethylene (130 μm) laminated film has a yield point strength in the direction perpendicular to the score of 2.5 to 3. When the processing is performed to 1 kgf, the elongation (strain) is reduced to 10% or less, and the toughness (tenacity) of the processed part is significantly reduced. Elongation of 20% or more can be maintained by the processing with the point strength, and the toughness of the processed portion can be maintained twice or more. This effect is not limited to this laminated film but can be similarly obtained with various other films. For example, in the case of polyethylene terephthalate (12 μm) / aluminum foil (7 μm) / polypropylene (25 μm), toughness of 1.5 to 2 times in yield point strength and about 2 times in yield point strain is obtained as compared with scoring. Can be

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 wide 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 becomes about 20 mm × 5 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.

Further, 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 large number of dot-like resin melting weakened portions can be obtained.

FIG. 16 shows a processing pattern when a laser beam is scanned and irradiated when the shape and dimensions of the cavity entrance of the kaleidoscope are 5 mm × 3 mm. The surface of the workpiece is melted to form a fine uneven pattern. Further, as shown in FIG. 16B, when the laser output is increased, the width of the melted portion is increased, and conversely, the unmelted portion is narrowed. The pitch between the stripes 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 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 may be scanned and radiated on a molecular orientation film to be a surface layer before, during, or after lamination, or an intermediate layer at any stage for producing a laminate, and linear tearing may be performed. It is possible to form a melt-weakened portion having a predetermined length to be a scheduled portion.

In FIG. 17, which shows an example of a laminate to be applied to bag making, the laminate 1 has a portion 18 to be folded back into opposing sheet portions 17a, 17b, and three portions 19a, 19b, and 19c to be heat-sealed. The linear tearing portion 13 due to the fusion weakening is formed at a small distance from and along the inner edge of the sealing portion 19c of the two sheet portions 17a and 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 18 to be folded to the melt-weakened layer 13 of one sheet 17a and the distance L1 from the portion 18 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 tearing of the packaging bag by hand can be performed smoothly.

Further, the packaging bag of the present invention may be provided with a tear start portion or the like serving as a tear start portion of the laminate by means known per se, but after the formation of the tear start portion or inspection of the tear start portion. In the step, a melt-weakening layer serving as a tear guide may be formed. 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 described more specifically with the following examples. Five 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、・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。単位はμｍ。
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：ラミネート面に印刷を施した二軸延伸ナイロンフィルム（興人　ボニールＲＸ）。
PA-2：二軸延伸ナイロン６フィルム（興人　ボニール　ＲＸ）。
Al：アルミニウム箔。
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ＰＧＴ)。
BPP：エチレンとのブロックコポリマーからなるポリプロピレンの無延伸フィルム（東レ合成フィルム　トレファン３７０１）。
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。
　また、カライドスコープとして次の２種類を、さらに焦点距離２．５インチのプラノコンベックスレンズおよび３．５インチのシリンドリカルレンズを準備した。カライドスコープＡ：長さ１３８ｍｍ、空洞部の入り口寸法３ｍｍ×６ｍｍの矩形、出口寸法６ｍｍ×６ｍｍの矩形。カライドスコープＢ：長さ１３８ｍｍ、空洞部の入り口寸法５ｍｍ×３ｍｍの矩形、出口寸法１８ｍｍ×３ｍｍの矩形。(図１３のＡ参照) また、落下試験、引裂強度測定、引張試験は以下の方法で行った。

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. The symbol “・” 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. The unit is μm.
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: A biaxially stretched nylon film (Kohjin Bonil RX) with a print on the laminate surface.
PA-2: Biaxially stretched nylon 6 film (Kojin Boneal RX).
Al: aluminum foil.
UOPP: Rolled uniaxially stretched polypropylene film (Nisseki Barilla PGT) with printing on the laminate surface.
BPP: An unstretched polypropylene film made of a block copolymer with ethylene (Toray Synthetic Film Trefan 3701).
LDPE: Low density polyethylene layer for extrusion coating.
LLDPE: Linear low density polyethylene film.
In addition, the following two types of callidescopes were prepared, and a planoconvex lens having a focal length of 2.5 inches and a cylindrical lens having a 3.5 inches were prepared. Callidescope A: a rectangle having a length of 138 mm, an entrance dimension of the cavity of 3 mm × 6 mm, and an exit dimension of 6 mm × 6 mm. Callidescope B: 138 mm in length, rectangle of 5 mm × 3 mm at entrance of cavity, rectangle of 18 mm × 3 mm at exit. (See FIG. 13A) The drop test, tear strength measurement, and tensile test were performed by the following methods.

[Drop test] At 5 ° C, the pouch was dropped on a concrete surface 10 times each from three heights, upright and inverted, and sideways, from a height of 120 cm to evaluate the presence or absence of bag breakage. did.

[Measurement of Tear Strength] After slightly tearing the laser-processed portion, the two portions were sandwiched between upper and lower chucks, respectively, and were torn using a tensile tester. The tearing speed was 300 mm / min, and the portion not torn was pressed by hand so as to be horizontal.

[Measurement of Material Strength in Laser Processing Section] A strip having a width of 15 mm was cut out perpendicular to the laser processing section, placed at the center of the portion where the laser processing section was to be stretched, and stretched using a tensile tester. The initial sample length of the stretched portion was 20 mm, and the tensile speed was 50 mm / min.

[Examples 1-1 to 4]
As shown in FIG. 10, a carbon dioxide laser beam was converted into a point-like aggregate beam by a planoconvex lens, and a weakened zone was processed at a speed of 13 m / min along the roll direction on the nylon surface of the laminate 5 through a kaleidoscope A. In addition, the distance between the exit surface of the kaleidoscope and the laminate was adjusted to 8 mm. The laser output was changed from 160 W to 220 W every 20 W (Examples 1 to 4). The surface state of the laminate thus obtained was observed with a scanning electron microscope. Under the conditions of 160 W and 180 W, the entire width of the weakened zone was about 6 mm, and the molten weakened line portion having a width of approximately 150 μm and the unmelted line portion also having a width of approximately 150 μm were alternately present. When the cross section was observed, the central portion of each melt-weakening line portion of the nylon layer was slightly thinner than the original thickness, and the edges were swelled. Further, under the conditions of 200 W and 220 W, the width of the melt weakening line was widened, and foaming was observed in a part of the melt weakening line portion of the nylon layer, but it did not lead to penetration. A Doypack-type standing pouch was prepared using the two-layer laminate, and 500 ml of a liquid detergent was filled and sealed. The laser-processed portions were positioned on the front and back of the pouch in parallel with the heat seal portion on the filling port side of the pouch and 15 mm below the top of the pouch. Also, a V-notch was cut in the edge heat-sealed portion serving as a tearing start portion. When a drop test was performed on these pouches, none of the pouches broke like the unprocessed pouch under any conditions. In addition, when the laser beam was torn from the laser-processed portion, each was torn linearly along the weakened zone and could be completely torn. Although the tearing property was better as the laser output was larger, it is considered that this was due to promotion of relaxation of molecular orientation of the nylon layer or foaming. Also, although the torn portion is visually linear, when observed with a scanning electron microscope, it is mainly torn along one melt-weakened line, and the tear is displaced in the middle and the adjacent melt-weakened line is Some parts have moved. As described above, the straight tearability was stably maintained by arranging a plurality of melt weakening lines in parallel at minute intervals. In addition, the displacement of the melt-weakened line portion on the front and back was almost within 1 mm, but was sometimes about 1.5 mm. Further, the tear strength was about 0.7 kgf under any condition. The nylon film layer of the laminate was peeled off, and the water content measured by the method specified in JIS K 0068 was 1.5% by weight.

[Comparative Examples 1 to 5]
As shown in FIG. 7, a carbon dioxide laser beam was condensed by a plano convex lens, and a line of weakening was processed on the nylon surface of the laminate 5 used in Example 1-1 at a speed of 13 m / min in the roll direction of the laminate. At this time, adjustment was performed so that the distance between the lens and the laminated body coincided with the focal length. Further, the laser output was changed every 5 W from 5 W to 25 W. (Comparative Examples 1 to 5) At an output of 10 W or more, the nylon layer sublimated during processing, a large amount of fume was generated, and the lens was soiled. Observation of the surface state of the thus obtained laminate with a scanning electron microscope showed that under the condition of 5 W, the remaining thickness of the nylon layer in the concave portion formed by laser processing was 80% of the original thickness in a thin portion. %, And almost no weakening line was formed. Further, under the condition of 15 W or more, the width of the weakened line was 1 mm or less, and the nylon layer on the outer surface completely disappeared and was broken. The condition of 10 W is an intermediate state between the conditions of 5 W and 15 W. In some cases, the formation of the weakening line is insufficient as in 5 W, and in some cases, the weakening line is broken like 15 W, and the remaining portion is broken. Had a slight nylon layer remaining. Using this two-layer laminate, a standing pouch was prepared in the same manner as in Example 1-1, and 500 ml of a liquid detergent was filled and sealed. In addition, it was considerably difficult to position the laser processing part at the same position on the front and back of the pouch, as compared with Example 1-1, because the width of the processing part was narrow. Furthermore, it was also difficult to cut the V-notch for starting tearing at an appropriate position. When a drop test was performed in the same manner as in Example 1-1, none was broken under the conditions of 5 W and 10 W, but 3 or 4 bags out of 50 were broken at 15 W or more. . Further, when the film was torn from the laser-processed portion, under the conditions of 5 W and 10 W, the tear largely deviated from the processed portion. Under conditions of 15 W or more, if the film was torn with caution, it was torn linearly along the line of weakness, but rarely slipped off the line of weakness. When the pouch under the condition of 15 W or more (Comparative Examples 3 to 5) was examined in detail, when the tear did not deviate from the line of weakness, the deviation of the line of weakness on the front and back was within 0.2 mm, but it did come off. Thickness was about 0.5 mm. Also, when the tear strength was measured, those with a deviation of the weakening line within 0.2 mm were about 0.7 kgf, while those with a deviation of 0.5 mm showed a value of 1.3 kgf or more. When it deviated from the line, a value of 4 kgf or more was shown. As described above, the tearability of the pouch of Comparative Example 1 showed an extremely strong dependence on the positional relationship between the weakened lines on the front and back, and the allowable range of the shift on the front and back for good tearing was about 0.2 mm.

　表２のように、実施例１−１〜４は比較例１〜５よりも、降伏点強度では僅かに高い値を示し、降伏点ひずみでは３倍程度大きい値を示した。これは、比較例ではレーザ加工部の深さに関係なく、一本しかない溶融弱化線部に応力が集中し局所的に変形したのに対し、実施例では多数の溶融弱化線部に応力が分散し、蛇腹状に大変形したことによる。 The material strength of the laser-processed portion was measured for each of the laminates prepared in Examples 1-1 to 4 and Comparative Examples 1 to 5. Table 2 shows the results.

As shown in Table 2, Examples 1-1 to 4 showed slightly higher values in yield point strength and about three times larger values in yield point strain than Comparative Examples 1 to 5. This is because, in the comparative example, the stress was concentrated on only one melt-weakened line portion and locally deformed irrespective of the depth of the laser processing portion, whereas in the example, the stress was applied on many melt-weakened line portions. This is due to dispersion and large deformation in the form of bellows.

[Example 1-5]
A standing pouch was prepared using Kaleidoscope B under the same conditions as in Example 1-1 except that the laser output was 300 W and the scanning speed was 60 m / min. The scanning direction was made to coincide with the longitudinal direction of the exit of the kaleidoscope. In the laser-processed portion of the pouch thus produced, a melt weakened line portion having a width of about 50 μm and an unmelted line portion having a width of about 300 μm were alternately present in a stripe shape with a width of 3 mm. This pouch was torn linearly along the laser-processed portion, and the pouch was easily torn in two to the last.

[Example 1-6]
A standing pouch was prepared under the same conditions as in Comparative Example 1 except that the distance between the lens and the laminate was 12 mm defocused and the laser output was 35 W. No fume was generated during processing. In the laser-processed portion of the pouch thus formed, a weakened zone consisting of one melting weakened line having a width of about 1.1 mm was formed. This pouch was torn linearly along the laser-processed portion, and the pouch was easily torn in two to the last.

[Example 1-7]
As shown in FIG. 9, a standing pouch was prepared under the same conditions as in Example 1 except that a cylindrical lens was used and the laser output was 120 W. In addition, the laminated body was positioned at a focal length of 3.5 inches, and scanned in a direction in which the processed portion became wide. In the laser-processed portion of the pouch thus formed, a weakened zone consisting of one melting weakened line having a width of about 6 mm was formed. This pouch was torn linearly along the laser-processed portion, and the pouch was easily torn in two to the last.

[Example 1-8]
Laser processing was performed on the PET surface of the laminate 1 using the same optical system as in Example 1-1, and a four-way heat seal pouch shown in FIG. 4 was created. Also, a V-notch was cut in the edge heat-sealed portion serving as a tearing start portion. The laser processing was performed at an output of 210 W and a speed of 13 m / min by scanning a laser beam. In the laser-processed portion of the pouch prepared in this manner, a melt weakened line portion having a width of about 150 μm and an unmelted line portion also having a width of about 150 μm were alternately present in a stripe shape with a width of 6 mm. A section was cut out from this portion and observed with a polarizing microscope. As a result, the outer PET layer was melted by laser processing at the melting weakened line portion, and the orientation was relaxed or lost. In addition, foaming was observed in a part of the fusion zone. The pouch was easily torn from the tear notch and linearly along the processed portion, and the pouch could be easily split into two pieces. In addition, the PET film layer of the laminate was peeled off, and the water content measured by the method specified in JIS K 0068 was 0.1% by weight.

[Example 1-9]
A four-way heat seal pouch was prepared under the same conditions as in Example 8, except that the laminate was adjusted using a vacuum dryer for 2 days. The laser-processed portion was almost the same as in Example 8, but no foaming was observed in the melt-weakened line portion. The PET film layer of the laminate was peeled off, and the water content measured by the method specified in JIS K 0068 was 0.05% by weight.

[Example 1-10]
A four-way heat seal pouch was prepared using the laminate 4 under the same conditions as in Example 1-8 except that the laser output was 190 W. The laser-processed portion was almost the same as in Example 1-8, and foaming was partially observed. The PET film layer of the laminate was peeled off, and the water content measured by the method specified in JIS K 0068 was 0.12% by weight. The pouch was easily torn from the tear notch and linearly along the processed portion, and the pouch could be easily split into two pieces. Also, 160 g of meat sauce was filled and sealed in 10 bags of this pouch, and subjected to retort sterilization at 121 ° C. for 20 minutes. Thereafter, a storage test at 35 ° C. for one month was performed. After storage, the contents were examined, but no abnormalities were found.

[Comparative Example 6]
A four-way heat seal pouch was prepared under the same conditions as in Example 10 except that the same optical system as in Comparative Example 1 was used and the laser output was set to 20 W. During processing, the PET layer sublimated, a large amount of fume was generated, and the lens was soiled. When the surface state of the thus obtained laminate was observed with a scanning electron microscope, the width of the weakened line was 0.4 mm, and the PET layer on the outer surface had completely disappeared and was broken. When a storage test similar to that of Example 1-10 was performed on 10 bags of this pouch, after storage, the contents changed from reddish brown to brown to dark brown, and all of them were altered. After cutting off the peripheral heat-sealed portion of the pouch and washing off the contents, when the pouch side wall was grooved with light, the aluminum foil was broken in the laser-processed portion.

[Example 1-11]
A four-way heat seal pouch was prepared under the same conditions as in Example 1-8, except that the laminate 3 was used. The laser-processed portion was almost the same as in Example 1-8, but a lot of foaming was observed in the nylon layer located below the PET layer. The pouch was easily torn from the tear notch and linearly along the processed portion, and the pouch could be easily split into two pieces. When a storage test similar to that of Example 1-10 was performed on 10 bags of this pouch, no abnormality was found.

[Comparative Example 7]
A four-way heat seal pouch was prepared under the same conditions as in Comparative Example 6, except that the laminate 3 was used. During processing, the PET layer or the nylon layer sublimated, a large amount of fume was generated, and the lens was soiled. In the laser-processed portion, similarly to Comparative Example 6, the width of the weakened line was 0.4 mm, and the outer layer from the PET layer to the nylon layer completely disappeared and was broken. When a storage test similar to that of Example 1-10 was performed on 10 bags of this pouch, the contents were discolored and all of them were altered, similarly to Comparative Example 6. The cause was due to the rupture of the aluminum foil.

[Example 1-12]
A four-way heat seal pouch was prepared under the same conditions as in Example 1-8, except that the output was 230 W using the laminate 2. The laser-processed portion was almost the same as in Example 1-8, but no foaming was observed in the melt weakened line portion. The stretched PP film layer of the laminate is peeled off and subjected to JIS
The water content as measured by the method specified by K0068 was 0.01% by weight or less. The pouch was easily torn from the tear notch and linearly along the processed portion, and the pouch could be easily split into two pieces.

包装 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 linear tearing scheduled part by fusion weakening, A is an example in which the linear tearing scheduled part is formed by the solid fusion weakening resin layer, B is the linear tearing scheduled part. C shows an example in which the portion to be linearly torn is formed of a dot-shaped melt-weakened 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 relationship between the shape of the entrance of a kaleidoscope, and the point-like aggregate beam formed. 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.

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 stacking a laminate made of a thermoplastic resin having molecular orientation, and the upper sheet and the lower sheet are at least partially weakened to be linearly torn. (1) the outer surface resin layer and / or the intermediate resin layer of the portion to be linearly torn is crossed over a range in which the width in the direction crossing the tearing direction is larger than 1 mm. (2) the outer surface resin layer and / or the intermediate resin layer of the portion to be linearly torn has a water content according to JIS K0068, which is continuous in the direction or intermittently in the transverse direction. An easily tearable packaging bag comprising 0.1% by weight or more of a thermoplastic resin, which forms a weakened resin layer by foaming of the resin. At least an outer surface layer and / or an intermediate layer are formed by stacking a laminate made of a thermoplastic resin having molecular orientation, and the upper sheet and the lower sheet are at least partially weakened to be linearly torn. (1) the outer surface resin layer and / or the intermediate resin layer of the portion to be linearly torn is crossed over a range in which the width in the direction crossing the tearing direction is larger than 1 mm. (2) the outer surface resin layer and / or the intermediate resin layer of the portion to be linearly torn is a weakened resin layer due to relaxation or disappearance of molecular orientation; and (3) The outer surface resin layer and / or the intermediate resin layer of the portion to be linearly torn is composed of a finely striped weakened resin layer arranged almost regularly. Easy-tear of the packaging bag to be. 3. The easily tearable packaging bag according to claim 2, wherein the 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 made of a film of polyester, polyamide or olefin resin stretched in at least one axis 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. (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 / nylon / metal foil / olefin resin in order from the surface.

Images