JPH10287361A - Easy-to-open wrapping material and packaging bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wrapping material and a packaging bag wherein they themselves are excellent in preservation for contents, while easiness in unsealing, that is easiness in starting a tear and easiness in guiding the tear is applied without substantially causing wear-out or the like of the wrapping material and further without dropping sealing strength and resistance against impact of a machined part. SOLUTION: The wrapping material is formed of a laminate comprising at least one layer of a molecule-oriented thermoplastic resin layer 2 and a heat-sealing thermoplastic resin layer inward with respect to the resin layer 2. A fusion weakened part 7 having a cross section comprising at least one valley or recess 7 and peaks or protrusions 8a, 8b on both sides of the valley or the recess 7 is formed on a side of the resin layer 2, wherein where an average thickness of the molecule-oriented thermoplastic resin layer 2 is t0 , a thickness of the thinnest part of the valley or the recess 7 is t1 , and a thickness of a summit of the peak or protrusions 8a, 8b is t2 , a value of t1 /t0 is 0.9 to 0.1, and a value of t2 /t0 is 1.05 to 2.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily-openable packaging material and an easily-openable packaging bag using the same, and more particularly, to an outer surface layer made of a molecularly oriented thermoplastic resin, It is composed of a laminate consisting of an inner surface layer made of a sealing thermoplastic resin, and has excellent storage stability and substantially reduces the seal strength and impact strength of the seal portion without substantially causing wear and tear of the packaging material. The present invention relates to a packaging material provided with easy-opening properties without being made, and a packaging bag using the same.

[0002]

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

[0003] However, the plastic film has a problem that the tearing strength is large and it is often difficult to tear by hand when taking out the contents.

[0004] For this reason, packaging bags provided with hand tearability, so-called easy-open packaging bags, have been used for a long time. The most typical example of the easy-open packaging bag has a notch called a notch at the edge of the heat seal, and stress concentration occurs at the tip of the notch, and the opening due to tearing of the laminated body is difficult. It is relatively easy to do.

[0005] However, in this type of easy-open packaging bag, the seal width of the notched portion is naturally reduced, and the strength of this portion of the bag cannot be prevented from decreasing, which is prevented. For this purpose, it is necessary to make the seal width at the seal edge sufficiently large to secure a sufficient residual width of the seal portion at the notch forming portion, and therefore, there is a problem that the amount of packaging material used increases. . Another problem is that notch chips are generated along with the formation of the notch, and special removing means and monitoring means are required so that the notch chips do not enter the product.

[0006] In addition, a packaging bag provided with tearability by hand on the bag itself, a so-called easy-open packaging bag has been used for a long time. The most typical example of the easily-openable packaging bag uses a laminated sheet in which a uniaxially stretched film provided with a 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.

[0007] The easily openable packaging bag using the above-mentioned laminated sheet has no problem in terms of bag breaking strength and easy tearability. It was necessary to attach a uniaxially oriented film to the entire surface of the sheet, which increased the cost of the easy-open packaging bag and wasted valuable resources. Also, the tear was limited to a straight one.

[0008] 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.

As a solution to the above-mentioned drawbacks of the notched packaging bag, it is already known to form a weakened portion other than the notch at or near the opening start portion of the packaging bag, for example, Japanese Patent Publication No. 61-39228. Publication contains at least 3
On the other hand, in a plastic sealed subdivided bag formed by sticking together a palm and sealing both end edge seal portions, a large number of scars are densely provided substantially on the edge line at the fused portion of the sheet constituting the bag. A sealed dispensing bag is described. It is also known to provide a large number of fine holes instead of the above-mentioned scars.

It is already known to form an opening line at a portion of a bag to be torn by a laser or the like.
No. 222,835 discloses that after blank forming of a liquid paper container, a carbon dioxide gas laser is radiated in a substantially horizontal direction from the surface layer side to the entire periphery near the upper end of the vertical portion of the outer rank to have a width of 1 mm.
A method for forming an opening line of a liquid paper container characterized by forming an opening line composed of a thin groove of not more than mm is described.

Japanese Unexamined Patent Publication No. Hei 4-327139 discloses a packaging bag having heat-sealed portions at both end edges, wherein tearing guide grooves formed at positions corresponding to each other on both sides of the packaging bag. About one edge from the side edge of the heat-sealed portion.
It describes an easy-open packaging bag that is positioned at an interval of at least mm, and also describes that the guide groove is formed by a laser.

[0012]

However, it is often difficult to achieve a good balance between the strength of the packaging material and the ease of opening by the conventional means for forming the weakened portion at the opening start portion or the portion to be torn. Face the facts. That is, the characteristics required for the easily-openable packaging bag are to easily introduce a cut for tearing and to correctly guide the tear along the line to be opened. In the means for weakening the starting portion or the means for forming grooves or the like by laser, although the tearing property is improved, the stress is simultaneously concentrated on the weakened portion, and the strength against dropping and other impacts is also reduced at the same time. There is a problem.

[0013] Further, in these machining methods, there is a problem that it is very difficult to control the machining, and that machining chips are generated. For example, in the processing method using a blade, a blade with a large number of fine and sharp blades or a single blade is pressed against the packaging material,
Processing is performed, but there is a problem that the thickness of the cut changes 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 are problems that the productivity is reduced and the equipment cost is increased. Further, there is also a problem that a large number of fine powders of the packaging material are generated due to cutting or abrasion, and this is mixed into the product.

Further, in the processing method using a laser, the laser light is focused on a spot of about 0.2 mm on the surface of the packaging material by a planoconvex lens or the like to volatilize the plastic on the surface of the packaging material. Although the line is formed, even if the packaging material position slightly fluctuates up and down, the packaging material may be completely or excessively cut. It is necessary to increase it very much, and there are also problems that productivity is reduced and equipment cost is increased. Further, there is also a problem that a part of the packaging material sublimes at a high temperature to generate fume and adhere to the packaging material. To prevent this, it is necessary to exhaust the fume. Further, even if the narrow groove on the front and back of the bag is slightly displaced, tearing becomes difficult, and the tear comes off from the narrow groove. 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. Furthermore, in the case where a thin score-shaped groove is provided, this portion is easily bent locally,
There is a problem in that the foil becomes fatigued during distribution and breaks linearly.

The present inventors have proposed a laminate for a packaging bag,
Using a laminate of at least one molecularly oriented thermoplastic resin layer and a heat sealable thermoplastic resin layer inside the molecularly oriented thermoplastic resin, so that the peaks and valleys described below have a specific relationship, It has been found that when irradiating with a laser beam, an easily-openable packaging material and a packaging bag which are excellent in preservability of contents and impact resistance and excellent in tear initiation property and tear guiding property can be obtained.

That is, an object of the present invention is not only to provide excellent preservability of the content itself, but also to substantially reduce the seal strength and the impact strength of the processed portion without substantially causing the wear and the like of the packaging material. An object of the present invention is to provide a packaging material and a packaging bag provided with easy-opening properties, that is, easy tearing startability and easy tear guideability without lowering.

Another object of the present invention is to provide an easy-open packaging material and a packaging bag which can easily impart tear resistance without special troublesome control and with high productivity. To provide.

[0018]

According to the present invention, there is provided a laminate comprising at least one molecularly oriented thermoplastic resin layer and a heat-sealable thermoplastic resin layer inside the molecularly oriented thermoplastic resin layer. A melting weakening portion having at least one valley or concave portion and a ridge or convex portion on both sides of the valley or concave portion formed on the side of the molecularly oriented thermoplastic resin layer. When the thickness of the molecularly oriented thermoplastic resin layer is t ₀ , the thickness of the thinnest portion of the valley or the concave portion is t ₁ , and the thickness of the peak portion or the top of the convex portion is t ₂ , t ₁ / t ₀ is satisfied. Characterized in that the value is from 0.9 to 0.1, especially from 0.8 to 0.5, and the value of t ₂ / t ₀ is from 1.05 to 2.0, especially from 1.1 to 1.8. An easy-open packaging material is provided.

According to the present invention, the wrapping material is formed such that the heat-sealing thermoplastic resin layer is superimposed on the wrapping material, and the melt-weakened portion is formed as a tear initiation portion or a tear guide portion. An easily openable packaging bag is provided.

The melting weakening portion in the present invention may be provided at a place where the packaging bag is torn, and may be formed at, for example, a tear start portion or a tear guide portion.
Further, in the packaging bag, it is preferable that the melt-weakened portion is provided on both sides of the facing laminate in an overlapping positional relationship.

In the packaging material and the packaging bag of the present invention, in the cross section passing through the thinnest portion, the distance between the crest and the top of the protrusion and the top of the crest and the top of the protrusion facing each other is 10 to 3000 μm.
m, particularly preferably 30 to 1500 μm.

In the melt-weakened portion, the valleys or recesses may be provided in a relation of a dispersed phase and the ridges or protrusions may be provided in a continuous phase, or the valleys or recesses and the ridges or protrusions may be provided in a relationship of a continuous phase. It may be formed linearly or perforated.
Further, the valleys or the recesses may be formed in a stripe shape or a stripe shape intermittent in the length direction, with the ridges or the protrusions interposed therebetween at a minute interval. To 3000 μm, especially 50 to 200
It is preferably in the range of 0 μm.

Further, as a preferred example, the melt-weakened portion has high peaks or projections (A) on both sides and a plurality of valleys or depressions (Alternately formed between the peaks or projections (A)) alternately. B) and a plurality of low peaks or projections (C).

In the laminate used in the present invention: 1. The molecularly oriented thermoplastic resin layer is made of a polyester, polyamide or olefin resin film stretched in at least one direction. 2. The molecularly oriented thermoplastic resin layer is composed of at least two layers, and a printing ink layer is formed between the layers. It is preferable that a metal foil is provided between the molecular orientation thermoplastic resin layer and the heat-sealing thermoplastic resin layer.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a laminate comprising at least one molecularly oriented thermoplastic resin layer and a heat sealing thermoplastic resin layer inside the molecularly oriented thermoplastic resin layer is used as a packaging material. .

In the present invention, the molecularly oriented thermoplastic resin is used because the molecular orientation of the thermoplastic resin enhances the mechanical strength, impact resistance, gas barrier property, heat resistance, transparency, etc. of the laminate. Because. Further, the uniaxial orientation of the thermoplastic resin also has an effect of improving tearability in the orientation direction. The heat sealing resin layer provided on the inner side of the molecularly oriented thermoplastic resin is for imparting heat sealing property to the packaging material.

In the present invention, the melt-weakening layer is formed utilizing the molecular orientation of the resin layer provided outside 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,
In the present invention, the resin layer located outside the laminate is melted,
By relaxing or eliminating this molecular orientation, it becomes possible to form a portion which is selectively weakened against tearing in the molten portion.

In FIG. 1 (enlarged sectional view) for describing the melt-weakened portion and the dimensional relationship thereof in the present invention, a melt-weakened portion 6 is formed on the surface of the molecularly oriented thermoplastic resin layer 2. The fusion weakened portion 6 has at least one valley or concave portion 7 in cross section and ridges or convex portions 8a and 8b on both sides of the valley or concave portion.

A valley or a recess 7 in the melt weakened portion 6
The formation of the peaks and the projections 8a and 8b is performed only when the molecularly oriented thermoplastic resin layer is irradiated with a laser beam having an energy intensity enough to cause substantially no volatilization of the resin but melting of the resin. It is a specific phenomenon that occurs, and it is still unknown how this phenomenon occurs. However, the resin that is irradiated and melted by the beam is pulled by the oriented resin in the vicinity (a type of shrinkage occurs). ), Valleys or depressions 7 and peaks or projections 8a, 8b.

In the valleys and recesses 7 in the melt-weakened portion 6, the resin is melted, the orientation is lost, and the thickness is reduced, so that the resin is easily torn. The portions or protrusions 8a and 8b have resistance to tearing due to some remaining orientation and an increase in thickness. For this reason, tearing is performed through the valleys or the concave portions 7, and the peaks or the convex portions 8 are formed.
a and 8b prevent the propagation of the tear to portions other than the melt weakened portion 6.

In the present invention, the thickness of the molecularly oriented thermoplastic resin layer 2 at a position other than the tear start portion or the tear guide portion is t ₀ , and the thickness of the thinnest portion of the valley portion or the concave portion in the tear start portion or the tear guide portion is t t _1, when the thickness of the crest or protrusion top was t _2, the value of t ₁ / t ₀ is 0.
9 to 0.1, especially 0.8 to 0.5 and t ₂ /
When the value of t ₀ is 1.05 to 2.0, particularly 1.1 to 1.8
It is also important that

That is, when the value of t ₁ / t ₀ is larger than the above range, tear initiation and tear guiding properties are insufficient. On the other hand, when this value is smaller than the above range, the bag breaking strength and the impact resistance of the melt-weakened portion are considerably reduced as compared with those in the above range, and the protection of the metal foil becomes insufficient. Absent. When the value of t ₂ / t ₀ is lower than the above range, the protection effect of the melt-weakened portion is lost, the toughness in the direction perpendicular to the melt-weakened portion is reduced, and the bag breaking strength is reduced. At the same time, the guideability of the tear tends to decrease. On the other hand, if this value exceeds the above range, stress concentration to valleys or recesses tends to occur, and processing becomes difficult, which is not practical.

In the present invention, in FIG. 2, the cross-sectional area of a peak or a convex portion is S ₁ and the cross-sectional area of a valley or a concave portion is S _2.
In this case, it is preferable that the ratio of S ₁ / S ₂ is in the range of 0.5 to 1.5 in order to improve tearability while maintaining sufficient strength. In a laser beam having a high energy density, such as a focus beam, the peaks or protrusions increase due to a large thermal effect, and the cross-sectional area S _1.
Is usually larger than the cross-sectional area S ₂ of the valley or the recess,
Their area ratio S ₁ / S ₂ is greater than 1.5.
On the other hand, with a laser beam from a kaleidoscope or a laser beam from a cylindrical lens, the thermal effect on the hills and projections is reduced, and the area ratio S ₁ /
S ₂ takes a value of 0.5 to 1.5.

The actual measured values are shown below. Laser light source Cross-sectional area ratio S ₁ / S ₂ Focus beam 5W 1.78 Focus beam 10W 1.91 Defocus beam 10W 0.90 Callide 100W6mmGAP 1.25 0.38 Callide 100W1mmGAP 0.81 0.65 Callide 120W1mmGAP 1.29 1.19 0.91

In the present invention, the melting weakening at the tear start portion or the tear guide portion is performed by continuously or discontinuously distributing in the plane direction over a range where the width d in the direction crossing the tear direction is larger than 1 mm. Is preferred. That is, by dispersing the heat for melting over a range wider than 1 mm, it is possible not only to avoid the fusing and the evaporation of the resin due to local heating, but also to shift the tearing start position and the guide position. To increase the tolerance of the resin, improve the ease of opening by enabling smooth tearing, and disperse the stress applied to the melt-weakening resin layer to prevent accidental bag breakage due to impact or the like. . Also, 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 opening by tearing is possible. When the melt weakening is performed over a range wider than 1 mm, when there is only one processing line, the distance between the peak or the convex top and the opposing peak or the convex top is larger than 1 mm. When a plurality of stripes are processed, the larger the number of stripes, the smaller the distance between the ridges or the ridges and the opposing ridges. However, if the distance is smaller than 10 μm, the effect of tearing is reduced.

In the present invention, the outer surface resin layer of the tear start portion or the tear guide portion is processed so as to be a finely dot-like or stripe-like melt-weakening resin portion which is arranged substantially regularly. Is particularly preferred. This is because in such a resin melt 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 this case, the tearing is performed in such a manner as to pass through the dots or stripes. Also,
It is preferable that the dot-shaped or stripe-shaped weakened resin layer has a pitch of 20 to 3000 μm in order to impart easy tearability without lowering the bag breaking strength of the bag.

In FIG. 3, which shows a preferred cross-sectional structure of the tear start portion and the tear guide portion in the present invention, the melt weakening portion 6 has high ridges or protrusions 8a, 8b (A) on both sides.
And a plurality of valleys or recesses 9 (B) and a plurality of low ridges or protrusions 10 (C) alternately formed between the ridges or protrusions 8a and 8b (A). The melt-weakened portion 6 of this shape is also essentially the same as that shown in FIG. 1, but a plurality of valleys or recesses 9 (B) are further included in the valleys or recesses 7 shown in FIG. And a plurality of low peaks or projections 10
The feature is that (C) is formed alternately. Of course,
Also in this case, the ridges or protrusions 8 (A) and the valleys or recesses 9 are formed.
(B) must satisfy the above-mentioned condition with respect to the thickness, and a valley or a concave portion 9 (B) is melted. It is substantially not melted, or even if partially melted, the degree of melting is low (partial). It should be understood that the valleys or the recesses B may be stripes continuous in a direction perpendicular to the figure, or may be dots intermittent in this direction. It is.

In the present invention, the melt-weakened portion is preferably formed by laser irradiation, particularly by a laser beam from a kaleidoscope or a laser beam from a cylindrical lens. That is, by performing laser irradiation on the outer surface resin layer of the tear start portion or the tear guide portion over a range in which the width in the direction crossing the opening direction is larger than 1 mm, the outer surface resin layer is melted, but its scattering is substantially reduced. It is possible to perform heating to such an extent that it does not occur in a natural manner, thereby forming an easily tearable melt-weakened resin layer without preventing loss of the resin material and without excessively reducing the strength of this portion. It is possible to do.

In the packaging material of the present invention, it is preferable to use a metal foil as an intermediate layer between the molecularly oriented thermoplastic resin layer and the heat-sealing thermoplastic resin layer. This is because the metal foil has a gas barrier property, gives the packaging material excellent preservation of contents, and gives the packaging material an appropriate rigidity (form retention) as well as flexibility. In the present invention, the use of a metal foil achieves particular advantages in relation to laser beam irradiation. In other words, the metal foil is an excellent reflector for laser light, and prevents the laser beam from reaching the heat-sealing resin layer, thereby preventing defects in the heat seal of the packaging material and preventing the laser light from being generated. Is effectively absorbed by the molecular alignment resin layer.

[Laminate (Packaging Material)] In the present invention, the flexible laminate (packaging material) constituting the container wall of the packaging bag is stretched (molecular) for imparting mechanical strength, heat resistance and the like. Orientation)
A plastic film, an olefin resin for providing heat sealing properties, or a metal foil for further providing a gas barrier property against oxygen and the like are used in combination and in the form of a laminate.

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 1
Polyamide (Ny) films such as 1, nylon 12, nylon 6 / nylon 6,6 copolymer: propylene-based polymer film (PP): polyvinyl chloride film: polyvinylidene chloride film: ethylene vinyl alcohol copolymer film ( EVOH) and the like. These films 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, as a heat-sealing resin film, low-, medium-, and high-density polyethylene (P
E), linear low-density polyethylene, isotactic polypropylene (PP), propylene-ethylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ion Cross-linked olefin copolymer (ionomer),
A modified olefin resin such as an olefin resin graft-modified with an ethylenically unsaturated carboxylic acid or an anhydride thereof;
A polyamide or copolyamide resin having a relatively low melting point or low softening point; a polyester or copolyester resin having a relatively low melting point or low softening point, or a combination of two or more thereof is used. These films are 15
It preferably has a thickness of 100 to 100 μm.

On the other hand, as a 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, chromic acid treatment, etc. are performed on 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, an aluminum alloy foil is used in addition to so-called pure aluminum. These metal foils have a thickness of 150
A film having a thickness of not more than μm, particularly 5 to 120 μm is used. In order to impart gas barrier properties, a gas barrier resin such as an ethylene vinyl alcohol copolymer, a nylon resin, or a cyclic olefin copolymer may be used alone or in combination of two or more kinds instead of metal foil. it can.

Suitable examples of the laminate include a layer structure from the inside to the outside, and include an olefin resin heat seal layer / aluminum foil / uniaxially stretched polypropylene film, an olefin resin heat seal layer / aluminum foil / biaxially stretched nylon film. , Olefin resin heat seal layer /
Aluminum foil / biaxially oriented polypropylene film, olefin resin heat seal layer / aluminum foil / biaxially oriented nylon film, olefin resin heat seal layer / aluminum foil / biaxially oriented polyethylene terephthalate film, olefin resin heat seal layer / two Examples include an axially stretched nylon film / aluminum foil / a biaxially stretched polyethylene terephthalate film, but are 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. 4, 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 / It has a layer structure of an inner layer 4 for heat sealing of an olefin resin. In FIG. 5, which shows another example of a suitable laminate, the 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 an inner layer 4 for heat sealing of a system resin.

The overall thickness of the laminate 1 is 30 to 2
It is preferably in the range of 00 μm, especially 40 to 150 μm. If 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 on the outer surface layer of the laminate in the thickness direction. Flexibility is lost, and it becomes difficult to impart tearability.

The laminate is manufactured by dry lamination,
It can be carried out by any means known per se, such as 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, sandwich lamination is performed by extruding an arbitrary resin between films or between a film and a resin-coated metal foil. In extrusion coating, an arbitrary resin is put on a film or a metal foil. This is done by extruding. 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), olefin resins graft-modified with ethylenically unsaturated carboxylic acids or anhydrides; A polyamide or copolyamide resin having a softening point; a polyester or copolyester resin having a relatively low melting point or a 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 anchoring agent can be applied to the surface on which the extruded resin layer is to be applied.

[Melted-Weakened Resin Layer and Its Formation] In the present invention, a laser beam is applied to the molecularly oriented thermoplastic resin layer of the above-mentioned packaging material (laminate), and the above-mentioned valley portion is applied to the irradiated portion of this resin layer. Or a melt-weakened portion composed of a concave portion and a peak portion or a convex portion. In order to form the valleys or depressions and the ridges or projections having the above-mentioned dimensional relationship, it is essential that the resin layer to be irradiated be molecularly oriented as described above. It is necessary that the energy intensity per unit area is within a certain range. The energy intensity can be adjusted by adjusting the input to the laser light source, but it is generally appropriate to increase the laser beam irradiation area or further adjust the intensity distribution.

In the present invention, the irradiation width in the direction transverse to the opening direction is more than 1 mm, preferably 1.5 to 10 m, in the tear start portion or the tear guide portion.
It is preferable to perform the heating over the range of m in order to avoid local excessive heating. In other words, 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 it is difficult to smoothly tear due to a slight shift of the tearing start position and the tearing guide part. 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 melt-weakened portion in the molecularly oriented thermoplastic resin layer may be provided at the tearing start portion of the packaging material, may be provided at the tearing guide portion of the packaging material, or may be provided so as to serve as both. Good. When the melt-weakened portion is provided at the tearing start portion, the size of the melt-weakened portion in the opening direction is not particularly limited as long as the cut easily enters the end of the packaging bag, but is generally not less than 0.5 mm. Preferably, it is in the range of 2 to 10 mm. If this dimension is too small, it tends to be difficult to form a tear initiation sufficient to continue the tear. In addition, the contour shape in the plane of the fusion weakening portion at the tearing start portion is a triangle, square, rectangle, rhombus, hexagon, circle, ellipse,
The shape may be an arbitrary shape such as a semicircle, an irregular shape, etc., and its area is generally 1 to 300 mm, corresponding to the dimensions described above.
It is in the range of ² . When the melting weakening portion is provided in the tearing guide portion, the dimension of the melting weakening portion in the opening direction is generally provided over the entire length in the tearing direction, but the range in which the opening by the tearing is substantially performed, for example, 2 mm of the full length. It may be provided partially over about a percentage or more.

In the melt-weakened portion of the outer surface layer of the laminate,
The fact that the molecular orientation has disappeared or relaxed can be confirmed by a measuring means known per se, for example, a birefringence method, an X-ray diffraction method, a fluorescence birefringence method, or the like.

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

In FIG. 6 showing the form of distribution of the surface of the melt-weakened portion at the tear start portion, A shows an example in which the tear-start portion 11 is formed by a solid melt-weakened portion (valley or recess) 7. B shows an example in which the tear start portion 11 is formed of a stripe-shaped melt-weakened portion (valley or concave portion) 9, and C shows the tear start portion 11.
Are formed by dot-shaped melt-weakened portions (valleys or recesses) 9. In the example of FIG. 6A, although the alignment resin layer 12 exists outside the tear initiation portion 11,
Only the melt-weakened resin 7 exists inside the tearing start portion 11, and no oriented resin in the original state exists. Of course, the ridges or protrusions 8 shown in FIG. FIG.
In the example B, the alignment resin layer 12 exists outside the tear start portion 11 via the ridges or protrusions 8, and the stripe-shaped melt-weakening resin portion ( A valley or a concave portion 9 and a stripe-shaped low ridge or a convex portion (oriented or low-oriented resin portion) 10 are alternately repeated. In the example of FIG. 6C, the tear start portion 11
Is located outside, and a low mountain (oriented or low-oriented resin) is provided inside the tear initiation portion 11.
The concave portions 9 of the molten resin are present in a dispersed phase in the 10 continuous phases.

In FIG. 7 showing the form of distribution of the surface of the melt-weakened portion in the tear guide portion 13, the distribution of the melt-weakened portion 9 is essentially the structure of FIG. Is not different from that of FIG.

In the present invention, the formation of the melt-weakened portion is not particularly limited, but it is preferable to form the portion by laser beam irradiation, in particular, a laser beam by a kaleidoscope or a laser beam by a cylindrical lens. That is, in a preferred embodiment of the present invention, since the laminate uses a metal foil that is an excellent reflector for laser, even when the energy density per unit area is low,
The heating of the molecular alignment resin layer is performed efficiently, and the melting weakening of the resin layer proceeds smoothly. Further, the laser irradiation on the outer surface resin layer of the laser beam tearing start portion or the tearing guide portion is performed when the width in the direction crossing the opening direction is 1 mm.
By performing the heating over a range larger than mm, it becomes possible to perform heating to such an extent that the outer surface resin layer is melted but does not substantially scatter, thereby preventing loss of the resin material, and It is possible to form the easily tearable melt-weakened resin layer described above without excessively losing the strength of the portion.

In the present invention, the molten resin portion 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 within a short time, and rapidly cooled to a temperature lower than the crystallization temperature when the heating is stopped. By doing so, the molten resin layer is in an amorphous state or a low crystallized 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, a linear or curved scanning irradiation of a carbon dioxide laser beam can be used. In this case, the output and the scanning speed of the laser beam are changed. Thereby, the thickness and the temperature of the molten layer can be controlled. Also, the width can be controlled by changing the laser beam diameter. The laser output is appropriately selected depending on the type of the constituent base material and the material of the ink layer. Conversely, when the degree of processing is increased, a material having a large laser absorption can be used.

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 the laminate is defocused. If necessary, scanning irradiation is performed to secure a predetermined irradiation area.

In FIG. 8 for explaining this embodiment,
The laser beam 30 is directed to a plano convex lens 31.
(Flat surface 32, Convex surface 33)
Irradiation is performed in a defocused state, that is, in a state where the defocus distance f0 is longer than the focus distance f.

Considering the case where the laser beam is normally irradiated, it is usual to focus on the position of the laminated body (f). In this case, the intensity distribution of the laser beam is as shown by a curve a in FIG. A steep Gaussian distribution results. Therefore,
The width is narrow (half width H0), 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. 8, the stacked body is irradiated with the focal position shifted (defocused). By doing this,
As shown by the curve b in FIG. 9, the intensity distribution of the laser beam has a smooth Gaussian distribution (half-width H1, H1 >> H0).
become. Therefore, the central portion does not become hot, no fume is generated, and a wide weakened portion is processed. 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 having a flat surface on one side and a convex surface on the other side and extending in the longitudinal direction) and extends in the processing direction. Irradiation is performed while scanning.

In FIG. 10 for explaining this embodiment, a laser beam 30 is applied to a cylindrical lens 34.
(Flat surface 32, Convex surface 35)
Irradiation is performed 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.This focused beam is scanned in a direction perpendicular to the line beam. In addition, it is possible to process a weakened portion that is substantially quadrangular and solid.
Of course, if the light is irradiated through one or several masking slits parallel to the scanning direction, several stripe-shaped weakened portions can be processed.

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

FIG. 11 for explaining the callide scope
In this case, the kaleidoscope 36 is a rectangular parallelepiped tube made of metal, has holes 37 of various shapes in the vicinity of the center thereof, and the inner surface 38 is plated with gold having high reflectivity. . Light overlaps at a portion where the wavelength of the laser light reflected by the inner surface 38 is shifted by an integer multiple, and light cancels out at a portion where the wavelength is shifted by a half wavelength, so that a fine interference pattern 40 is formed.

The cavity entrance 37 of the kaleidoscope 36
When the laser beam 30 is condensed by the planoconvex 31, the laser beam at the exit of the kaleidoscope 36 becomes a point-like aggregate beam as shown in FIG. 12 if the cross section of the cavity is rectangular. By scanning this beam, a number of stripe-shaped scanning beams as shown in FIG. 13 are formed. Thereby, the strength of the packaging material does not decrease, and the tearability does not decrease.

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

It is also possible to change the size of the entrance and the size of the exit of the cavity of the kaleidoscope, which has the advantage that a very large weakened portion can be machined. For example, as shown in FIG. 14A, the entrance is 5 mm × 3 mm.
If the outlet is 18 mm × 3 mm in size, the size of the point-like aggregate beam is about 20 mm × 5 mm. The pattern of the point-like aggregate beam is shown in FIG.
It becomes like B of.

When the kaleidoscope is tilted from the optical axis of the plano-convex lens as shown in FIG. 15A, as shown in FIG. spread.

Further, as shown in FIG. 16, the shape of the entrance 37 of the cavity of the kaleidoscope is not limited to a square,
Triangular and hexagonal shapes are also possible.

FIG. 17 shows a processing pattern when a workpiece is irradiated with a laser beam for a short time when the shape and dimensions of the cavity entrance of the kaleidoscope are 5 mm × 3 mm. The surface of the workpiece is melted to form a fine valley convex pattern. The pitch between the points was about 0.3 mm.

In the present invention, the laser beam is
A carbon dioxide laser is used, but its output is generally
Those in the range of 10 W to 1.2 kW are suitable, but of course are not limited to this.

In the present invention, the formation of the weakened layer by melting the resin can be carried out before, during or after bag making. For example, an arbitrary stage for manufacturing a laminate, that is, a laser beam is irradiated on a molecular orientation film to be a surface layer before lamination, during lamination, or after lamination to form a melt-weakened portion having a predetermined pattern. Can be done.

[Packaging Bag and Method for Producing the Same] The easily-openable packaging bag of the present invention is obtained by laminating the above-mentioned laminates so that the heat-sealable resin layers face each other, and making the laminate by heat sealing or the like. It is formed.

FIG. 18 shows an example of a packaging bag of the present invention (a three-sided heat-sealing pouch).
No. 0 has a folded portion 21 on one side and edge heat seal portions 22a, 22b and 22c on three sides, and these folded portions 21 or three edge heat seal portions 22a and 22a,
At least a part of 2b, 22c is provided with a tear start portion 11 formed of a melt-weakened portion, and a tear guide portion 13 extending from the tear start portion 11 in the tear direction. still,
The tear start portion 11 and the tear guide portion 13 may be formed by different processes, or may be formed by a single process at the same time. In the latter case, the end of the melt weakened portion 13 starts to tear. Department. This type of packaging bag is manufactured by stacking one laminate and heat-sealing 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 is not substantially melted, and the same is applied to the following examples. The formation of the melt weakened portion 13 is performed by a method described later.

In FIG. 19, which shows another example (four-side heat seal pouch) of the packaging bag of the present invention, this easily openable packaging bag 20 has four edge heat-seal portions 22a, 22b,
2c, 22d, and four-sided edge heat seal portions 22
At least a part of a, 22b, 22c, and 22d is provided with a tear initiation portion 11 due to melting weakening of the molecular alignment resin and a tear guide portion 13 extending in the tear direction from the tear initiation portion.

FIG. 20 shows still another example (pillow packaging pouch) of the packaging bag of the present invention.
0 denotes a gasket stick 24 extending to the center by heat sealing
And the folded portions 21a and 21b on both sides parallel to the attachment of the palms.
And the edge heat seal portion 22 in a direction perpendicular to the joint palm
a, 22b, and the folded portion 21, the palm joint 24, or the two edge heat seal portions 22a, 22b.
Is formed at least in part with a tear initiation portion 11 due to the weakening of the molecular alignment resin by melting and a tear guide portion 13 extending in the tearing direction from this.

In the packaging bag of the present invention, the width of the heat seal at the edge heat seal portion and at the joint between the palms is preferably in the range of 3 to 15 mm from the viewpoint of preventing the breakage of the bag and reducing the material used. In the present invention, it is possible to form a melt-weakened resin layer, that is, to form a tear initiation portion, by utilizing the fact that the outer surface layer of the laminate of these heat seal portions substantially maintains the molecular orientation as it is. Is what you do.

In the pillow packaging pouch of the present invention, when the weakened portion 11 is provided along the intersection of the palm joint 24 and the edge sealing portion 22, the pouch 24 is used as a grip portion, and the pouch device along the joint palm 24 is provided. This is convenient because the wall can be used as a tear guide so that it can be opened along the palm joint 24.

In FIG. 21, which shows an example of a laminate (packaging material) to be applied to bag making, this laminate 1 has a portion 25 to be folded back into opposing sheet portions 27a and 27b, and a three-way to be heat-sealed. Parts 26a, 26b and 2
6c, and the portion 11 to start tearing due to fusion weakening is formed so as to straddle the respective edges of the upper sealing portions 26a, 26b of both sheet portions 27a, 27b. Further, the tear guiding portion 13 extending in the tearing direction from this is also formed by melting and weakening the molecular alignment resin. In this case, since the melt-weakened layers 11 and 13 are formed over a width of 1 mm or more,
The distance L1 from the part 25 to be folded back to the melt-weakened layer 11, 13 of one sheet 27a, and the distance L1 from the part 25 to be folded back to the melt-weakened layer 11, ₁ of the other sheet 27b.
And the distance L ₂ to 3 do not match exactly, even if there is some deviation between the two, it is possible to smoothly open hand tearability of the packaging bag.

Further, in the present invention, 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 step or after the bag production. Before or after the filling of the contents, the formation of the melt-weakened layer can be performed.

[0082]

The present invention will be described more specifically with reference to the following examples.

[0083] Three types of laminates shown in Table 1 were prepared.

[Table 1] Note 1) The symbol in the table indicates an adhesive interface that was dry-laminated using a urethane-based adhesive. Further, the symbol / indicates a bonding interface by sandwich lamination, and the bonding surface was coated with a urethane-based anchor agent as needed. Note 2) The values in parentheses in the table indicate the thickness of each substrate.
The unit is μm. Note 3) In the table, base materials indicated by abbreviations indicate the following, respectively. PET: Biaxially stretched polyethylene terephthalate film printed on the laminate surface (Toray Miller P-6)
0). PA: Biaxially stretched nylon 6 film (Kojin Boneal
RX). Al: aluminum foil. UOPP: Rolled uniaxially stretched polypropylene film (Nisseki Vallilla PG) printed on the laminate surface. CPP: 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.

Further, five types shown in Table 2 were prepared as callidescopes, and a planoconvex lens having a focal length of 2.5 inches and a cylindrical lens having a 3.5 inches were prepared.

[Table 2]

The drop test and the 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 a height of 120 cm, in a state of upright and inverted, and in a horizontal state, and evaluated for the presence or absence of bag breakage. did. [Tensile test (measurement of material strength in laser processing part)] A 15 mm wide strip is cut out from the laser processing part perpendicularly to the processing direction, and placed at the center of the part where the processing part is extended.
The film was stretched using a tensile tester. The initial sample length of the stretched portion was 20 mm, and the tensile speed was 50 mm / min.

Embodiments 1 to 3 As shown in FIG. 11, a carbon dioxide laser beam is converted into a point-like aggregate beam by a planoconvex lens, and a speed of 13 m / min. The weakened zone was machined with. Note that the distance between the exit surface of the kaleidoscope and the laminate was adjusted to 8 mm. Also,
The laser output was set to three conditions of 190 W (Example 1), 210 W (Example 2), and 230 W (Example 3). The surface state of the laminate thus obtained was observed with a scanning electron microscope. Under all conditions, the total width of the weakened zone is about 6
mm, and the melt weakened line portion having a width of about 150 μm and the unmelted line portion also having a width of about 150 μm were alternately present.
When the cross section was observed, the central portion of each of the melt-weakening lines of the PET layer was slightly thinner than the original thickness, and the edges were in a raised state. Using this laminate, a four-way heat seal pouch was prepared, filled with 160 g of meat sauce, and sealed by heat seal. 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. After performing the retort sterilization at 121 ° C for 20 minutes,
A drop test was performed. Neither condition broke the bag as did the raw pouch. 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. The higher the laser power, the better the tearing property,
This is probably due to the promotion of relaxation of the molecular orientation of the layer. In addition, although the torn portion is visually linear, when observed with a scanning electron microscope, it is torn mainly along one melting weakening line, and the tear is displaced in the middle and the adjacent melting weakening line Some parts have moved. As described above, the straight-line tearing property was stably maintained by arranging a plurality of melt weakening lines in parallel at minute intervals.
In addition, the deviation of the melt weakening line portion on the front and back is almost 1 mm.
Within about 1.5 mm, there was no effect on the tearability. The pouch under each condition was subjected to a storage test at 35 ° C. for one month. After saving,
Examination of the contents revealed no abnormalities.

Comparative Examples 1 to 3 As shown in FIG. 8, a carbon dioxide laser beam was condensed by a plano convex lens, and the PET of the laminate 1 used in Example 1 was used.
A weakened line was formed on the surface at a speed of 13 m / min in the roll direction of the laminate. At this time, the distance between the lens and the laminate was adjusted to match the focal length. The laser output is 5W
(Comparative Example 1), 15 W (Comparative Example 2), and 25 W (Comparative Example 3) were used. At an output of 15 W or more, the PET 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 by a scanning electron microscope showed that under the condition of 5 W, the remaining thickness of the PET layer in the concave portion formed by laser processing was 95% 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 is 0.6 mm or less, and the outer surface PE
The T layer completely disappeared and was broken. Using this laminate, a four-way heat seal pouch was prepared in the same manner as in Example 1, filled with a meat sauce, sealed, and subjected to a retort treatment. In addition, it was difficult to position the laser-processed portion at the same position on the front and back of the pouch, as compared with Example 1, because the width of the processed portion was narrow. After performing retort sterilization at 121 ° C. for 20 minutes, a drop test was performed in the same manner as in Example 1.
At 15 W or more, 3 to 4 bags broke out of 50 bags. Also, when tearing from the end of the laser processing part,
Under the condition of W, it could not be torn. Under the condition of 15 W or more, tearing was possible, but three out of ten bags were torn off the weakening line in the middle. A detailed examination showed that those whose tears did not deviate from the line of weakness had a deviation of the weakened line on the front and back within 0.2 mm, while those which did not deviate were approximately 0.5 mm. As described above, the tearability of the pouches of Comparative Examples 2 and 3 showed an extremely strong dependence on the positional relationship between the weakened lines on the front and back, and the allowable range of the displacement on the front and back for good tearing was about 0.2 mm. When a pouch under 15 W or more conditions (Comparative Examples 2 and 3) was subjected to the same storage test as in Example 1, after storage, the contents had changed from reddish brown to brown to dark brown. Cut off the peripheral heat seal part of the pouch,
After washing off the contents, the side wall of the pouch was exposed to light and found that the aluminum foil was broken in the laser-processed portion.

With respect to each of the laminates prepared in Examples 1 to 3 and Comparative Examples 2 and 3, the material strength of the laser-processed portion was measured. Table 3 shows the results.

[Table 3] As shown in Table 1, Examples 1 to 3 exhibited higher yield point strength and yield point strain than Comparative Examples 2 and 3. Others
In the pouches of Comparative Examples 2 and 3, the aluminum foil was easily broken not only by tension but also by bending.

Example 4 A standing pouch was prepared using Kaleidoscope B under the same conditions as in Example 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 formed, a 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 processing part, and the pouch could be easily torn in two to the last.

Example 5 A four-way heat seal 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 processing part, and the pouch could be easily torn in two to the last.

Example 6 A four-way heat seal 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 as shown in FIG. 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 3 mm was formed. This pouch was torn linearly along the laser processing part, and the pouch could be easily torn in two to the last.

Example 7 A four-way heat seal pouch was prepared under the same conditions as in Example 1 except that the laminated body 2 was used and the laser output was 190 W.
The pouch was easily torn from the opening notch and linearly along the processed portion, and the pouch could be easily torn into two pieces.

Example 8 A four-way heat seal pouch was prepared under the same conditions as in Example 1 except that the laminated body 3 was used and the output was 230 W. The pouch was easily torn from the opening notch and linearly along the processed portion, and the pouch could be easily torn into two pieces.

In Examples 1 to 8 and Comparative Examples 2 and 3, the original film thickness t ₀ , the thickness t ₁ of the thinnest portion in the valley-shaped thinned portion, and the thickness of the mountain-shaped thickened portion Table 4 shows the average values of t ₂ , values of these ratios t ₁ / t ₀ and t ₂ / t ₀ , the distance d between the opposing peaks, and the pitch P between adjacent valleys.

[Table 4]

Example 9 Using the laminated body 1 having a width of 100 mm, a pouch having a weakened portion for starting opening at one position of the bent portion 21 of the three-way heat seal pouch shown in FIG. 18 and near the edge seal portion was manufactured. It was created using a bag-type filling machine. The weakened portion was obtained by intermittently unwinding the laminate from a roll using a photoelectric mark, and processing the PET surface of the outer layer with a laser. Processing is shown in FIG.
As described above, a carbon dioxide laser beam was converted into a point-like aggregate beam using a kaleidoscope C via a planoconvex, and the laser output was 30 W and the irradiation time was about 60 msec. The distance between the exit surface of the kaleidoscope and the laminate was adjusted to 8 mm. The pouch of Example 1 thus created has a large number of dot-shaped weakened portions in a range of 3 mm in the longitudinal direction and 3 mm in the width direction of the laminate at a pitch of about 0.35 mm in the bent portion 21. Was. When a section was cut out from this part and observed with a polarizing microscope, the PET layer on the outer surface was melted by laser processing in the weakened part, and the orientation was relaxed or lost. In addition, the vicinity of the center of the fused portion was thinned like a valley, and conversely, the periphery was thickened like a mountain. In these pouches, even when the contents were filled with liquid soup or the like, there was nothing that broke the bag from the melt-weakened part. Also, this pouch could be easily torn from the processed part without any notch.

Example 10 A pouch was made in the same manner as in Example 9 except that Kaleidoscope D was used. This pouch had the same melting weakened portion as the pouch of Example 1, and showed the same performance.

Example 11 A pouch was made in the same manner as in Example 9 except that Kaleidoscope E was used. This pouch had the same melting weakened portion as the pouch of Example 1, and showed the same performance.

Comparative Example 4 A pouch was made in the same manner as in Example 1 except that laser processing was not performed. This pouch could not be torn from any part of the bent part 21.

[0099] For Examples 9-11, the original film thickness t ₀ and the thickness of the thinnest portion in the thinned portion in trough t _1, the thickness t ₂ of the thickened portion like a mountain, these ratios Table 5 shows the values t ₁ / t ₀ and t ₂ / t ₀ and the pitch P between adjacent valley portions.

[Table 5]

Examples 12 to 15 As shown in FIG. 11, a carbon dioxide laser beam was converted into a point-like aggregate beam by a planoconvex lens.
Through the laminate PA-1 (15) · LLDPE (13
A weakened zone was formed on the nylon surface of 0) along the roll direction at a speed of 13 m / min. Note that the distance between the exit surface of the kaleidoscope and the laminate was adjusted to 8 mm. The laser output was from 160 W (Example 12) to 220 W (Example 15).
(Examples 12, 13, 1)
4, 15). 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 is about 6 mm, and the width of the weakened zone is 15 mm.
A melt weakened line portion of about 0 μm and an unmelted line portion of about 150 μm width 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 end portions were in a raised state. 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 of the nylon layer, but it did not lead to penetration. A Doypack-type standing pouch was prepared using the two-layer laminate, filled with 500 ml of a liquid detergent, and sealed by heat sealing. 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. In addition, V is applied to the edge seal portion serving as the tearing start portion.
Notch carved. 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. The tearing property was better as the laser output was larger, but this is probably due to the promotion of relaxation of the molecular orientation of the nylon layer or the foaming. In addition, although the torn portion is visually linear, when observed with a scanning electron microscope, it is torn mainly along one melting weakening line, and the tear is displaced in the middle and the adjacent melting weakening line Some parts have moved. As described above, the straight-line tearing property was stably maintained by arranging a plurality of melt weakening lines in parallel at minute intervals. In addition, the displacement of the melt weakening line portion on the front and back was almost 1 mm or less, and some were about 1.5 mm. In addition, tear strength of any condition,
It was about 0.7 kgf. Incidentally, the nylon film layer of the laminate was peeled off, and the water content measured by the method specified by JIS K 0068 was 1.5.
% By weight.

[0101]

According to the present invention, the outer surface thermoplastic resin layer is molecularly oriented by forming a melt weakened portion in the molecular orientation resin layer by utilizing the molecular orientation of the outer surface layer of the laminate. While maintaining the advantage of the above, it is possible to form a portion which is weakened to tear selectively with respect to the molten portion.

Further, it is possible to form a valley or a concave portion in which the resin is melted and a ridge or a valley portion on both sides thereof in the melt-weakened portion. In addition to being relaxed or disappearing, the reduced thickness facilitates tearing, while the ridges and projections have some residual orientation and increased thickness. It is resistant to tearing. For this reason, the tearing is easily performed through the valleys or the concave portions, and the ridges or the convexities prevent the propagation of the tears to portions other than the melting weakened portion.

Further, by making the width in the direction perpendicular to the tearing direction of the melt-weakened portion larger than 1 mm, it is possible to form a smooth melt-weakened portion while avoiding evaporation of resin. Increases the tolerance for deviation of the tearing start position, enables smooth tearing and improves easy-openability, and further disperses stress applied to the melt-weakened resin layer to prevent accidental bag breakage due to impact or the like. It is also possible. Also, 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 opening by tearing is possible.

According to a preferred embodiment of the present invention, when at least the tearing start portion or the outer surface resin layer of the tearing guide portion is formed with a weakly weakened resin layer in the form of fine dots or stripes arranged in a substantially regular manner, 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.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view for explaining a fusion weakened portion and a dimensional relationship thereof in the present invention. )

FIG. 2 is a cross-sectional area S _{1 of a} peak portion or a convex portion in a melting weakened portion.
And is an explanatory view illustrating the cross-sectional area S ₂ of the valley to the recess.

FIG. 3 is an enlarged cross-sectional view illustrating a weakened portion in a preferred embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating an example of a laminate suitably used in the present invention.

FIG. 5 is a cross-sectional view showing another example of a laminate suitably used in the present invention.

FIG. 6 is an explanatory diagram showing a surface state of a tear start portion due to melt weakening, where A is an example in which the tear start portion is formed of a solid melt-weakened resin layer, and B is a stripe-like molten portion in which the tear start portion is formed. In the example formed of the weakened resin layer, C indicates an example in which the tearing start portion is formed of the dot-shaped melt weakened resin layer.

FIG. 7 is an explanatory view showing an example of a surface state of a tear guide portion due to melting weakening.

FIG. 8 is an explanatory diagram showing an example in which a laser beam is condensed by a plano-convex lens and irradiated onto the laminate in a defocused state according to one embodiment of the present invention.

FIG. 9 is a graph showing an intensity distribution of a laser beam in the example of FIG.

FIG. 10 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.

FIG. 11 is an explanatory view showing an example in which a laser beam is guided to a kaleidoscope to irradiate a laminated body according to still another preferred embodiment of the present invention.

FIG. 12 is an explanatory diagram for explaining a point-like aggregate beam when a kaleidoscope having a square entrance and an exit is used.

FIG. 13 is an explanatory diagram showing a linear beam when scanning is performed using the kaleidoscope of FIG. 12;

FIG. 14 is an explanatory diagram showing a dimensional relationship between an inlet and an outlet of a kaleidoscope and a linear beam formed.

FIG. 15 is an explanatory diagram showing a relationship between a mode in which the kaleidoscope is displaced from the optical axis and a point-like aggregate beam formed thereby.

FIG. 16 is an explanatory diagram showing several examples of the relationship between the shape of the entrance of the kaleidoscope and the formed point-like aggregate beam.

FIG. 17 is a front view showing an example of a structure of a molten resin weakened portion formed by the method of FIG. 11;

FIG. 18 is a plan view showing an example (a three-side heat seal pouch) of the packaging bag of the present invention.

FIG. 19 is a plan view showing another example (a four-sided heat seal pouch) of the packaging bag of the present invention.

FIG. 20 is a plan view showing still another example (pillow packaging pouch) of the packaging bag of the present invention.

FIG. 21 is a front view showing an example of a laminate (packaging material) to be attached to bag making.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated body 2 Outer layer 3 Intermediate layer 4 Inner layer 5 2nd intermediate layer 6 Melt weakening part 7 Melt weakening part (valley part-concave part) 8 Peak part-convex part 9 Melt weakening part (valley part-concave part) 10 Mountain part- Convex portion (oriented or low-oriented resin portion) 11 Tear start portion 12 Oriented resin layer 13 Tear guide portion 20 Easy-open packaging bag 21 Folded portion 22 Edge heat seal portion 24 Attached joint 25 Part to be folded 26 Heat sealed To-be-suited part 27 Sheet part 30 Laser beam 31 Plano convex 32 Flat surface 33 Convex surface 34 Cylindrical lens 35 Convex surface 36 Callidescope 37 Cavity entrance 38 Inner surface 40 Interference pattern

Claims (6)

[Claims] 1. A packaging material formed from a laminate comprising at least one molecularly oriented thermoplastic resin layer and a heat-sealable thermoplastic resin layer inside the molecularly oriented thermoplastic resin layer. On the side of the oriented thermoplastic resin layer, a melt-weakened portion having a cross section including at least one valley or concave portion and ridges or convex portions on both sides of the valley or concave portion is formed, and the molecularly oriented thermoplastic resin layer is formed. Is the average thickness of t ₀ , the thickness of the thinnest portion of the valley or the concave portion is t ₁ , and the thickness of the peak portion or the top of the convex portion is t
When a _2, easily openable packing material values of t ₁ / value of t ₀ is 0.9 to 0.1 and t ₂ / t ₀ is characterized in that 1.05 to 2.0 . 2. The easy-open packaging material according to claim 1, wherein the melt-weakened portion is formed by irradiating a laser beam passing through a kaleidoscope. 3. The easy-opening packaging material according to claim 1, wherein said melt-weakened portion is formed by irradiation with a laser beam passed through a cylindrical lens. 4. The packaging material according to any one of claims 1 to 3, wherein the packaging material is overlapped so that the heat-sealable thermoplastic resin layer faces each other, and the melt-weakened portion serves as a tear start portion or a tear guide portion. Easy-to-open packaging bag made from a bag. 5. The easily-openable packaging bag according to claim 4, wherein the melt-weakened portions are provided on both sides of the facing laminate in an overlapping positional relationship. 6. A metal foil is provided between the molecular orientation thermoplastic resin layer and the heat-sealing thermoplastic resin layer.
6. The easily openable packaging bag according to any one of claims 1 to 5.