WO2016136962A1 - Easily peelable sealant film and easily peelable packaging bag using same - Google Patents

Abstract

Provide is an easily peelable sealant film for a laminate material, the film being characterized by having a layer to be laminated and a heat seal layer, and by being uniaxially drawn in the manufacturing process, wherein the layer to be laminated contains, as a main component, a polyester resin having crystallinity, and the heat seal layer contains a first dicarboxylic acid component and a first diol component as main components and also contains, with respect to the total mass of the heat seal layer, 50 mass% or more of an amorphous copolymerized polyester resin including at least one component from among a second dicarboxylic acid component and a second diol component.

Description

Sealant film having easy peelability and easy peel packaging bag using the same

The present invention relates to a sealant film having excellent low adsorptivity and easy peelability, and a packaging bag using the same.

The packaging bag manufactured by heat-sealing the sealant film which has easy peel property can peel off a heat seal part easily, and can take out the contents easily. Therefore, it is widely used in the fields of food, cosmetics, medicines, etc.

Many conventional easy peel sealant films are based on polyethylene resin. It has been practiced to impart easy peelability to polyethylene resins by blending or polymer alloying incompatible components such as polypropylene resins and polystyrene resins.

However, polyethylene resins have the property of easily adsorbing aroma components and medicinal components. Therefore, there is a problem that the amount of components of the contents is reduced. Therefore, easy peel sealant films based on polyester resins have been developed. Polyester-based resins such as polyethylene terephthalate resin are difficult to adsorb aroma components and medicinal components, and are well known as low adsorptive materials. For example, JP-A-5-229050 discloses a heat sealing layer formed of a mixture of a low crystalline polyester resin and an olefin thermoplastic elastomer and optionally a polyester thermoplastic elastomer, and a polybutylene terephthalate. Disclosed is an easily peelable packaging material comprising a resin layer. In JP-A-5-229050, when a polyester resin is used as the heat sealing resin, it is low in crystallinity to solve the problem that a large force is necessary for opening since it does not have easy peelability. An olefin-based thermoplastic elastomer is mixed with a polyester resin. However, since the olefin-based thermoplastic elastomer inhibits low adsorptivity, the easily peelable packaging material of Japanese Patent Laid-Open No. 5-229050 does not have low adsorptivity even though it is excellent in easy peelability.

Japanese Patent No. 5182183 discloses an easily openable laminated film having a three-layer structure of a heat seal layer, an adhesive resin layer and a base material layer. In Japanese Patent No. 5182183, the heat seal layer is mainly composed of a mixture of a non-crystalline polyethylene terephthalate resin and a polybutylene terephthalate copolymer or a single resin, and the adhesive resin layer is mainly composed of an acid-modified polyolefin layer. The base layer is mainly composed of polyolefin. In Japanese Patent No. 5182183, the main component of the adhesive resin layer is made of an acid-modified polyolefin resin in order to realize delamination between the heat seal layer and the adhesive resin layer at the time of opening. However, by using a maleic anhydride modified polyolefin resin, it is unclear whether the low adsorptivity is excellent, and there is also a problem that the cost is increased by using a laminated structure.

As described above, when a component different from the polyester resin is contained in order to impart easy peelability to the sealant film, there is a problem that the low adsorption is inhibited. Therefore, development of a sealant film in which low adsorptivity and easy peelability are compatible is desired.

Unexamined-Japanese-Patent No. 5-229050 Patent No. 5182183 gazette

In view of the above problems, it is an object of the present invention to provide a sealant film having excellent properties for both low adsorptivity and easy peelability, and an easy peel packaging bag using the same.

One embodiment of the present invention is a sealant film having easy peelability for a laminate material, which has a layer to be laminated and a heat seal layer, and the layer to be laminated is made of a polyester resin having crystallinity as a main component. The heat seal layer comprises a non-crystalline co-crystal comprising a first dicarboxylic acid component and a first diol component as main components, and further comprising at least one of a second dicarboxylic acid component and a second diol component. Provided are a sealant film comprising a polymerized polyester resin in an amount of 50% by mass or more of the total mass of the heat seal layer, and uniaxially stretched in a manufacturing process, and a packaging bag using the sealant film.

According to the present invention, an easy peel packaging bag having excellent low adsorptivity and easy peelability by using a sealant film having excellent properties for both low absorbency and easy peelability and using the sealant film Can be provided.

FIG. 1 is a schematic cross-sectional view of the sealant film of the present invention. FIG. 2 is a schematic cross-sectional view of a laminate using the sealant film of the present invention. FIG. 3 is a partial sectional schematic view of the easy peel packaging bag of the present invention. FIG. 4 is a schematic plan view of the easy peel packaging bag of the invention. FIG. 5 is a schematic view of a peeling direction test sample using the sealant film of the present invention. FIG. 6 is a schematic view showing a method of measuring the peel strength. FIG. 7 is a schematic view showing the state of the test sample after measurement of peel strength. FIG. 8 is a graph showing the relationship between peel strength and tensile distance when measuring peel strength. FIG. 9 is a schematic cross-sectional view showing the state of the heat seal layer after peeling.

Hereinafter, the configuration of the present invention will be described in detail.

The cross-sectional schematic diagram of the sealant film 1 concerning this invention is shown in FIG. As shown in FIG. 1, the sealant film 1 of the present invention has a layer to be laminated 3 and a heat seal layer 5 laminated on the layer to be laminated 3. The sealant film 1 of the present invention is produced by uniaxially stretching a laminated film obtained by laminating a heat seal layer on a layer to be laminated.

<Laminated layer>
In the present invention, the layer to be laminated is made of a polyester resin having crystallinity as a main component. The term "mainly" means that the polyester resin having crystallinity is 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, particularly preferably 99% by mass or more Represents that. Further, having crystallinity means that a peak (melting point) associated with melting of crystals is observed in the range of 20 to 300 ° C. (heating rate: 10 ° C./min.) In differential scanning calorimetry (DSC). .

The to-be-laminated layer which has a polyester resin which has crystallinity as a main component can be oriented and crystallized by extending | stretching.

The layer to be laminated may contain other resins as long as it can be oriented and crystallized by drawing, but it is preferable that the layer to be laminated is made only of polyester resin.

Examples of crystalline polyester resins include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate.

In a preferred embodiment, the crystalline polyester resin is polyethylene terephthalate resin (PET). PET is excellent in heat resistance and moldability, and is used in large amounts for films and bottles. Moreover, since it is cheap and can procure resin, since it is a resin very economically reasonable, it can be used conveniently.

The polyester resin having crystallinity which is a main component of the layer to be laminated may contain plural kinds of dicarboxylic acid components as long as the layer to be laminated has crystallinity.
Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, (anhydride) phthalic acid and 2,6-naphthalenedicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid and dodecane Aliphatic dicarboxylic acids such as dicarboxylic acids, dimer acids having 20 to 60 carbon atoms, (maleic anhydride), maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, hexahydrophthalic acid (anhydride), hexahydroterephthalic acid, etc. Hydroxycarboxylic acids such as alicyclic dicarboxylic acid, p-hydroxybenzoic acid, lactic acid, β-hydroxybutyric acid, ε-caprolactone, and polyfunctional carboxylic acids such as (anhydride) trimellitic acid, trimesic acid (anhydride) and the like An acid can be mentioned.

The polyester resin having crystallinity which is a main component of the layer to be laminated may contain plural kinds of diol components as long as the layer to be laminated has crystallinity.
Examples of the diol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, and the like. Aliphatic diols such as 6-hexanediol, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, alicyclic diols such as 1,4-cyclohexanedimethanol and 1,4-cyclohexanediethanol, ethylene oxide of bisphenol A and bisphenol S, Alternatively, aromatic diols such as propylene oxide adducts, and polyfunctional alcohols such as trimethylolpropane, glycerin and pentaerythritol can be mentioned.

The layer to be laminated may be, if necessary, commonly used additives such as antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, flame retardants, inorganic fine particles, organic fine particles, coloring agents, etc. It may contain an additive.

<Heat seal layer>
In the present invention, the heat seal layer contains a non-crystalline copolyester resin. Here, “non-crystalline” means that even after the sealant film is stretched in the manufacturing process, the crystal is in the range of 20 to 300 ° C. (heating rate: 10 ° C./min.) In differential scanning calorimetry (DSC). It says that the peak (melting point) accompanying melting is not seen. Such a polyester resin has good heat sealability because oriented crystallization does not occur by stretching. The heat seal layer contains a copolymerized polyester resin having non-crystallinity as a main component, and specifically, the copolymerized polyester resin having non-crystallinity in a proportion of 50% by mass or more of the total mass of the heat seal layer Including.

The non-crystalline copolyester resin comprises the first dicarboxylic acid component and the first diol component as main components, and further comprises at least one component of the second dicarboxylic acid component and the second diol component. Specifically, the second dicarboxylic acid component is contained in a range of 10 mol% to 50 mol%, preferably 20 mol% to 40 mol%, based on the total dicarboxylic acid component. The second diol component is contained in a range of 10 to 50 mol%, preferably 20 to 40 mol%, based on the total diol components. The total content of the second acid component and the second diol component is preferably contained in the range of 40 mol% or less.

By including at least one component of the second dicarboxylic acid component and the second diol component within the above range, it is possible to form a non-crystalline heat seal layer in which oriented crystallization does not occur due to stretching.

As the first and second dicarboxylic acid components, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, (phthalic anhydride), 2,6-naphthalenedicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacine Acid, azelaic acid, dodecanedicarboxylic acid, dimer acid having 20 to 60 carbon atoms, (anhydride) maleic acid, fumaric acid, itaconic acid, citraconic acid, aliphatic dicarboxylic acids such as mesaconic acid, (anhydride) hexahydrophthalic acid, Alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hydroxycarboxylic acids such as p-hydroxybenzoic acid, lactic acid, β-hydroxybutyric acid, ε-caprolactone, and the like (anhydride) trimellitic acid, trimesic acid, (anhydride) pyromellitic acid Mention may be made of polyfunctional carboxylic acids such as acids.

As the first and second diol components, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,4-butanediol, 1,5 -Aliphatic diols such as pentanediol, 1,6-hexanediol, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, alicyclic diols such as 1,4-cyclohexanedimethanol and 1,4-cyclohexanediethanol, bisphenol A And aromatic diols such as ethylene oxide or propylene oxide adducts of bisphenol S, and polyfunctional alcohols such as trimethylolpropane, glycerin and pentaerythritol. In a particularly preferred embodiment, ethylene glycol is used as the first diol component, and neopentyl glycol component or 1,4-cyclohexanedimethanol is used as the second diol component.

In one embodiment, the non-crystalline copolyester resin comprises terephthalic acid as the dicarboxylic acid component, non-crystalline comprising ethylene glycol as the first diol component, and neopentyl glycol component as the second diol component. Preferred are copolyethylene terephthalate resins. This resin is referred to as neopentyl glycol copolymerized polyethylene terephthalate resin (NPG copolymerized PET).

In NPG copolymerized PET, NPG is preferably contained in a range of 20 mol% or more and 40 mol% or less based on all diol components. When the content of NPG is less than 20 mol%, the crystallinity of the resin is generally strong. Therefore, the crystallinity of the heat seal layer becomes high after the sealant film is stretched, and the heat sealability can not be obtained. On the other hand, when the content of NPG exceeds 40 mol%, the polymerization time for producing the resin becomes long, and the productivity decreases, which is not preferable economically. The content of NPG in the NPG copolymerized PET is more preferably in the range of 25 to 35 mol% based on the total diol component. Within this range, better heat sealability can be obtained.

The NPG copolymerized PET may further contain other diols as well as ethylene glycol and NPG as diol components, and in this case, the content of the other diol components is in the range of less than 10% by mole based on the total diol components. Is preferred.

As described above, the heat seal layer contains 50% by mass or more, more preferably 90% by mass or more of the non-crystalline copolymerized polyethylene terephthalate resin, based on the total mass of the heat seal layer. When the content of the non-crystalline copolymerized polyethylene terephthalate resin is less than 50% by mass, the heat sealability is not stable. Furthermore, the heat seal start temperature rises.

The heat seal layer may, if necessary, be a commonly used additive, such as an antioxidant, a heat stabilizer, an antistatic agent, an ultraviolet light absorber, a flame retardant, inorganic fine particles, organic fine particles, a colorant, etc. It may contain an additive.

<Production method of sealant film>
The crystalline polyester resin constituting the layer to be laminated and the non-crystalline copolyester resin constituting the heat seal layer may be produced by a commonly used polyester resin production method, for example, a direct esterification method or the like. It can be produced by a transesterification method or the like.

The sealant film of the present invention can be produced by a known method used to produce a two-layer laminated film. For example, it can be produced by a coextrusion method. In the co-extrusion method, the resin forming the layer to be laminated and the resin forming the heat seal layer are respectively melted by an extruder, merged in a T-die mold equipped with a multi-manifold system and extruded, and rapidly cooled by a cooling roll. A laminated film is produced by cooling.

The sealant film 1 of the present invention is characterized in that the laminated film in which the heat seal layer is laminated on the layer to be laminated is further uniaxially stretched. By uniaxially stretching the laminated film, the crystalline polyester resin constituting the layer to be laminated 3 can be oriented and crystallized.

By the crystallization of the layer-to-be-laminated 3, the low adsorptivity of the layer-to-be-laminated 3 can be improved. As the crystallinity of the layer 3 to be laminated is higher, the low adsorptivity is improved.

Furthermore, the interlayer strength between the layer to be laminated 3 and the heat seal layer 5 can be reduced by the crystallization of the layer to be laminated 3. When the sealant film is stretched, the layer to be laminated 3 is oriented and crystallized, while the heat seal layer 5 is not oriented and crystallized. Thus, the interlayer strength between the layer to be laminated 3 and the heat seal layer 5 is reduced by the orientation crystallization of only the layer to be laminated 3, and the peeling between the layer to be laminated 3 and the heat seal layer 5 Improves the quality. This makes it possible to produce a sealant film having excellent easy peelability.

As described above, the sealant film 1 of the present invention is composed of the to-be-laminated layer mainly composed of the polyester resin having crystallinity and the heat seal layer mainly composed of the copolyester resin having non-crystallinity. As a result, it is possible to impart easy peelability while improving low adsorptivity. Therefore, both excellent low adsorptivity and easy peelability can be achieved.

<Stretch ratio>
As a method of uniaxially stretching the laminated film in which the heat seal layer is laminated on the layer to be laminated in the manufacturing process of the sealant film of the present invention, known methods such as a roll method and a tenter method can be used. It is more preferable to use a roll system, since the method of drawing by the circumferential speed difference between rolls is inexpensive as an apparatus. Stretching is preferably performed in a temperature range of 70 to 120 ° C.

The stretching ratio in uniaxially stretching the laminated film is preferably in the range of 3.0 to 5.0 times in the longitudinal direction. As the draw ratio is larger, the crystallinity of the layer to be laminated is higher, and the low adsorptivity is improved. In addition, the interlayer strength between the layer to be laminated and the heat seal layer is reduced, and the peeling becomes easy. When the draw ratio is less than 3.0 times, the interlayer strength between the layer to be laminated and the heat seal layer is not sufficiently reduced, and the releasability is not improved. In addition, the low adsorptivity is not sufficiently improved. On the other hand, when the draw ratio exceeds 5.0 times, the film may break when stretched, so the film forming property becomes unstable.

<Thickness of sealant film>
In the stretched sealant film, the thickness ratio of the layer to be laminated to the heat seal layer is preferably in the range of 3: 1 to 8: 1. If the ratio of the thickness of the layer to be laminated to the thickness of the heat seal layer is less than 3 times, the heat shrinkage behavior at the time of heat seal may be large, and thus a stable heat seal strength may not be obtained. A sealant film in which the thickness of the layer to be laminated exceeds eight times the thickness of the heat seal layer makes it difficult to prepare a production facility, and productivity is low. Therefore, the thickness ratio is preferably 8 times or less.

The thickness of the heat seal layer after stretching is preferably in the range of 1 μm to 5 μm. If the thickness of the heat seal layer is less than 1 μm, there is a problem that stable heat seal strength can not be maintained. On the other hand, when the thickness of the heat seal layer exceeds 5 μm, the peel strength at the initial stage of opening (initial opening strength) is increased, so the peelability may be reduced.
The thickness of the layer to be laminated is appropriately selected from the thickness of the heat seal layer and the ratio of the thickness of the layer to be laminated to the thickness of the heat seal layer.

<Laminated material>
According to the present invention, there is provided a laminate using the above-described sealant film. The cross-sectional schematic diagram of the laminate material 2 is shown in FIG.

As shown in FIG. 2, the laminate 2 has a base film layer 7 and a sealant film laminated on the base film layer.

Although the base film layer 7 is not limited to these, a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyamide film, a biaxially stretched polypropylene film, and the like are suitably used.

The sealant film is laminated such that the to-be-laminated layer 3 faces the base film layer 7. If necessary, a barrier layer may be provided between the layer to be laminated 3 and the base film layer 7. Although a barrier layer is not limited to these, Metal vapor deposition films, such as aluminum, a transparent silica vapor deposition film, aluminum foil, etc. are used suitably.

The sealant film, the substrate film layer and the barrier layer may each optionally be adhered using an adhesive. The adhesive can be a known adhesive that can be used to bond the resin film, and is appropriately selected depending on the components of the sealant film, the base film layer, and the barrier layer.

<Easy peel packaging bag>
In accordance with the present invention, there is provided an easy peel packaging bag using the above-described laminate material. FIG. 3 shows a partial cross-sectional schematic view of the easy peel packaging bag 10. As shown in FIG. 3, in the easy peel packaging bag 10, the first laminate material 2 and the second laminate material 2 'are laminated and heat sealed. The first laminate material 2 has a base film layer 7, a layer to be laminated 3, and a heat seal layer 5. The second laminate material 2 ′ has a base film layer 7 ′, a layer to be laminated 3 ′, and a heat seal layer 5 ′. The first laminate material 2 and the second laminate material 2 'are pasted together so that the heat seal layers 5 and 5' face each other.

The first laminate is a laminate produced using the sealant film according to the present invention. The second laminate material 2 ′ includes a to-be-laminated layer composed of a polyester resin having crystallinity as a main component, and a first dicarboxylic acid component and a first diol component as main components, and further a second dicarboxylic acid component And a non-crystalline copolyester resin containing at least one component of a second diol component, containing 50% by mass or more of the total mass of the heat seal layer, and a heat seal layer laminated on the layer to be laminated It is a laminating material containing the 2nd sealant film and the 2nd substrate film laminated so that the to-be-laminated layer of this 2nd sealant film may be opposed.

As the second laminate 2 ', a laminate produced using the sealant film of the present invention may be used. The second sealant film can be made into the sealant film of the present invention by uniaxially stretching in the manufacturing process. As described above, it is more preferable that both the first laminate material and the second laminate material be laminate materials using the sealant film according to the present invention because they are excellent in low adsorptivity.

When both of the first laminate material and the second laminate material are laminate materials using the sealant film according to the present invention, the same laminate materials may be used, but the types, amounts, etc. of the components differ. It may be a material.

The packaging bag of the present invention is characterized in that the easy peelability is developed only in the direction orthogonal to the direction in which the sealant film is stretched, and the easy peelability is not developed in the direction parallel to the stretched direction. Here, the “perpendicular direction” means a direction of about 90 ° with respect to the stretching direction of the sealant film, and does not strictly refer to the direction of 90 °. For example, it indicates a direction of 80 to 100 ° with respect to the stretching direction.

When each of the first laminate material and the second laminate material is a laminate material using the sealant film according to the present invention, the first sealant film stretches the first laminate material and the second laminate material. And the second direction is the same as the direction in which the second sealant film is stretched, and the opening direction of the packaging bag (ie, the peeling direction) is designed to be orthogonal to the direction in which the sealant film is stretched. Be done.

When the first laminate material uses the sealant film of the present invention and the second laminate material does not use the sealant film of the present invention, the first sealant film is uniaxially stretched in the opening direction. It is designed in the direction orthogonal to the vertical direction.

In addition to the fact that the interlaminar strength of the layer to be laminated and the heat seal layer is reduced by uniaxially stretching (longitudinal stretching) as a factor for developing easy peelability in the direction (lateral direction) orthogonal to the stretching direction of the sealant film, It is presumed that it is related that the sealant film is less likely to tear in the lateral direction. Moreover, when the sample after peeling was actually analyzed by FT-IR, it was found that delamination occurred between the layer to be laminated and the heat seal layer.

When both of the laminates of the two sheets use the sealant film according to the present invention, it is preferable that the draw ratio of the sealant film constituting each is different. As described above, the interlayer strength between the layer to be laminated and the heat seal layer decreases as the draw ratio increases. By making the draw ratio of the sealant film different between the first laminate material and the second laminate material, the interlayer strength of the sealant film of the first laminate material and the second laminate material is different. As a result, peeling occurs between the layer to be laminated of the sealant film and the heat seal layer in the laminate material having the lower interlayer strength at the time of peeling, so the surface after peeling becomes smooth without fuzzing.

The difference in draw ratio between the draw ratio of the first sealant film of the first laminate material and the draw ratio of the second sealant film of the second laminate material is more preferably 0.2 or more. For example, when the draw ratio in the second laminate material is 3.0, the draw ratio in the first laminate material is preferably 3.2 or more. When the sealant film is not stretched, the stretch ratio is considered to be 1.

When the stretching ratio difference of the sealant film is 0.2 or more, as described above, the surface after peeling becomes smooth without fuzzing. The reason is considered to be that delamination occurs in the sealant film in which the draw ratio is large, that is, the crystallinity of the layer to be laminated is high and the interlayer strength is low. The peel strength (heat seal strength) depends on the laminate material having a larger draw ratio. Therefore, the peel strength does not change even if the draw ratio of the smaller draw ratio is further reduced and the draw ratio difference is increased. Therefore, the upper limit of the difference in draw ratio is not particularly limited. However, since the higher the draw ratio is, the higher the low adsorptivity is, it is advantageous that the draw ratio difference is not too large, that is, one draw ratio is not too low.

In the packaging bag of the present invention, the peel strength at opening is preferably in the range of 3 to 15 N / 15 mm width, which is a standard required for the packaging bag. More preferably, the peel strength is in the range of 3 to 6 N / 15 mm width. The peel strength can be in the desired range by adjusting the draw ratio of either one of the laminates.

FIG. 4 is a schematic view showing an example of the easy peel packaging bag 10. In FIG. 4, the packaging bag has a rectangular shape, the upper portion of the drawing being an opening, and the lower portion of the drawing being a bottom surface. The bottom of the packaging bag is all heat sealed at the ends of the laminate. The side of the packaging material is heat-sealed to about half the length of the end of the laminate material. The opening is heat-sealed so as to form two sides of a triangle at the opening start point located inside from the end of the laminate and the opening start point and the end of the heat seal location on the side surface. The packaging bag of such a shape can be opened with a laminate material which is not heat-sealed at the opening, and since the heat-sealed area at the opening start point is small, the peeling strength at the initial stage of opening is small and the opening is easy. It has the advantage of being

The aspect of the packaging bag is not limited to that shown in FIG. 4 and, for example, the entire peripheral edge of the laminate may be heat sealed. Also, the shape may be arbitrarily selected.

As described above, in the present invention, a polyester film having crystallinity in the layer to be laminated is oriented and crystallized by stretching a sealant film using a polyethylene terephthalate resin for the layer to be laminated. As a result, it is possible to impart easy peelability to the sealant film and to further improve the low adsorptivity of the layer to be laminated. Therefore, it is possible to provide a sealant film in which low adsorptivity and easy peelability are compatible. Furthermore, stretching reduces the thickness of the sealant film, which is advantageous due to low adsorption. Therefore, according to the present invention, it is possible to provide a packaging bag in which the aroma component and the medicinal component are difficult to be adsorbed, and the contents can be easily taken out at the time of opening.

Moreover, the packaging bag manufactured using the sealant film of this invention is excellent in low adsorption property, since a sealant film consists of polyester system and it carries out the extending | stretching process. In addition, since easy peelability is simultaneously exhibited by the stretching treatment, it is suitably used for foods, cosmetics, and pharmaceuticals.

Example 1
<Production of First Sealant Film>
The sealant film was produced using the to-be-laminated layer which consists of a polyethylene terephthalate (PET) resin, and the heat seal layer which consists of neopentyl glycol copolymerized polyethylene terephthalate (NPG copolymerized PET) resin.

Co-extrusion of PET resin and NPG copolymerized PET resin at a temperature of 280 ° C. such that the ratio of the thickness of the layer to be laminated to the thickness of the heat seal layer is 6: 1 using a T-die mold The mixture was quickly cooled by a cooling roll to prepare a two-layered laminated film. The content of neopentyl glycol in the NPG copolymerized PET resin was 30 mol% with respect to the total amount of diol components.

Next, the laminated film was heated to a range of 90 to 120 ° C., and uniaxially stretched (longitudinal stretching) by a roll stretching method so that the total thickness of the film was 12 μm. The uniaxial stretching ratio was 4.2. After longitudinal stretching, the film forming process was completed by rapidly cooling with a cooling roll without performing so-called transverse stretching, performing corona treatment on the layer side to be laminated, and winding in a roll.

<Production of first laminate material>
The 1st laminate material was produced using the 1st sealant film produced above and the substrate film layer. Three-layer structure in which a 12 μm thick biaxially oriented polyester (PET) film, a 20 μm thick low density polyethylene (LDPE) film, and a 7 μm thick aluminum foil are laminated in this order as a base film layer Film was used. Here, an aluminum foil was used as a barrier layer. The base film layer is produced by laminating a PET film and an aluminum foil by extrusion lamination using LDPE.

Subsequently, the first surface of the aluminum foil to which nothing is bonded and the to-be-laminated layer of the first sealant film prepared above are dry-laminated using a two-component curing type isocyanate adhesive. The laminate material of

<Production of Second Sealant Film>
A second sealant film was produced in the same manner as the first sealant film except that the uniaxial stretching ratio was changed to 3.8 times.

<Production of second laminate material>
A second laminate was produced in the same manner as the first laminate except that the second sealant film was used instead of the first sealant film.

<Production of test sample>
A laminate was prepared by laminating the first laminate material prepared above and the second laminate material so that the stretching directions of the respective sealant films would be the same. In this laminate, one end in the direction perpendicular to the stretching direction of the sealant film and one end in the parallel direction of the stretching direction were heat sealed. The heat sealing was performed under the conditions of 150 ° C., 0.2 MPa and 1 second. A test sample was cut out from the heat-sealed laminate. The test sample has a strip-like shape with a width of 15 mm, and has a heat sealing point at one end in the longitudinal direction. As shown in FIG. 5, a test sample peeled off in the direction perpendicular to the drawing direction (also referred to as the transverse direction) is taken as sample (I), and a test sample peeled off in the direction parallel to the drawing direction (also referred to as the longitudinal direction) ).

[Examples 2 to 15]
In production of the first sealant film and the second sealant film, the content of neopentyl glycol in the NPG copolymerized PET resin, the ratio of the thickness of the layer to be laminated to the thickness of the heat seal layer, and the draw ratio are shown in Table 1 A sealant film, a laminate and a test sample were produced in the same manner as in Example 1 except that the values described in were changed.

Comparative Example 1
Test samples were produced in the same manner as in Example 1 except that a low density polyethylene (LDPE) film was used as the sealant film of the first and second laminates.

Comparative Example 2
As a sealant film, a linear low density polyethylene resin (LLDPE) and a modified polyethylene resin modified with maleic anhydride (modified PE) are used, and a three-layered structure of LLDPE / modified PE / NPG copolymerized PET is laminated in order The laminated film was produced by coextrusion molding using a T-die mold. Next, the LLDPE surface was subjected to a corona treatment and wound up in a roll to complete the film forming step. The layer to be laminated of this laminated film is LLDPE / modified PE, the ratio of the thickness of the sealant film to the thickness of the layer to be laminated, and the thickness of the heat seal layer is changed to the values described in Table 1, and a sealant film is produced. First and second laminates were produced in the same manner as in Example 1 except that stretching was not performed. The test sample was produced like Example 1 using the produced 1st and 2nd laminate material.

Comparative Example 3
The same laminate material as in Example 1 was used as the first laminate material. As the second laminate material, the same laminate material as the laminate material in Comparative Example 2 was used. Test samples were produced in the same manner as in Example 1 using these laminates.

[Comparative Examples 4 to 5]
In each of the production of the first sealant film and the second sealant film, the content of neopentyl glycol in the NPG copolymerized PET resin, the thickness of the sealant film, and the draw ratio were changed to the values described in Table 1 As in Example 1, a sealant film, a laminate, and a test sample were prepared.

Comparative Example 6
A sealant film and a laminate were produced in the same manner as in Example 1 except that the draw ratio was changed to the value described in Table 1 in the production of the first sealant film and the second sealant film. Test samples (I) and (II) of Comparative Example 6 were produced in the same manner as Example 1 using the produced laminate material.

Comparative Example 7
A sealant film and a laminate were produced in the same manner as in Example 1 except that the draw ratio was changed to the value described in Table 1 in the production of the first sealant film and the second sealant film. A test sample of Comparative Example 7 was produced in the same manner as Example 1 using the produced laminate material. However, in the test sample of Comparative Example 7, the first laminate material and the second laminate material were stacked and heat-sealed so that the stretching directions of the respective sealant films were orthogonal to each other. The stretching direction serving as the reference of the peeling direction of the test sample was based on the stretching direction of the first laminate material, that is, based on the stretching direction of the sealant film having a high stretching ratio, and this test sample was taken as (III).

<Evaluation of crystallinity after stretching of the layer to be laminated>
The crystallinity of the heat seal layer after stretching the sealant film was evaluated for Examples 1 to 15 and Comparative Examples 1 to 7. In the differential scanning calorimetry (DSC), if no peak (melting point) associated with the melting of the crystal originating from other than the layer to be laminated is found in the range of 20 to 300 ° C. (heating rate: 10 ° C./min.) It was evaluated as having no nature, and when a peak (melting point) associated with melting of crystals was observed, it was evaluated as having crystallinity.

The results are shown in Table 1. In Examples 1 to 15 and Comparative Examples 2 to 4, 6, 7, and 8, all of the heat seal layers in the first and second laminates were evaluated as having no crystallinity. On the other hand, the heat seal layers in the first and second laminate materials of Comparative Example 5 were all evaluated as having crystallinity.

<Openability evaluation>
Peelability and Peel Strength Peelability and peel strength were evaluated using the test samples produced in Examples 1 to 15 and Comparative Examples 1 to 7. The peel strength is also referred to as heat seal strength. Evaluation was performed based on the method of calculating | requiring the heat seal strength of JISZ-0238. Specifically, as shown in FIG. 6, with the heat seal portion of the test sample at the center, both ends of the test sample are attached to the upper and lower grips of the tensile tester. Thereafter, the lower part of the grip was moved at a constant speed to pull the heat seal portion, and the maximum load between them was taken as the peel strength of the test sample.

As evaluation of peelability, when the heat-sealed part was pulled by the above-mentioned method, as shown in FIG. 7 (A), it was regarded as peelable if the film could be completely separated without being torn. Such characteristics are characteristics necessary for producing an easy peelable packaging bag. An example of the change in peel strength at this time is shown in (A ′) of FIG. The test samples have almost the same peel strength from the start to the end regardless of the tensile distance.

On the other hand, when the heat-sealed portion was pulled, as shown in FIG. 7 (B), when the film was torn or broken, it was considered that there is no releasability. An example of the change in peel strength at this time is shown in FIG. 8 (B ′). In the test sample, the peel strength sharply increases after the start of tension, and after exceeding the peak, sharply decreases and is interrupted halfway. This indicates that the film has broken. Such properties make it impossible to produce an easy peel packaging bag.

Table 2 shows the test samples used and the evaluation of peelability and the results of peel strength. Here, the test sample used is defined by any of the following (I), (II) and (III) as described above.

(I) Test sample in which the peeling direction is perpendicular to the stretching direction (II) Test sample in which the peeling direction is parallel to the stretching direction (III) In the stretching direction of the sealant film in which the peeling direction is high Test samples parallel to each other (however, the stretching directions of the respective sealant films are orthogonal)
Examples 1 to 15 were all evaluated using the test sample of (I). Since Comparative Example 1 is not stretched, the peeling direction is not defined. Comparative Examples 2 to 5 were all evaluated using the test sample of (I). Comparative Example 6 was evaluated using the test sample of (II). Comparative Example 7 was evaluated using the test sample of (III). In Comparative Example 7, since the stretching directions of the first laminate material and the second laminate material are orthogonal to each other, the peeling direction is parallel to the stretching direction with respect to the first laminate material. For the laminate material of 2, the peeling direction is perpendicular to the stretching direction.

Examples 1 to 15 were shown to have peelability. The peel strength at this time was in the range of 3.2 to 11.0 N / 15 mm, and it was shown that the peel strength was suitable to impart easy peelability to the packaging bag. In Comparative Example 4, it was shown that the sealant film was not stretched, and in such a case, it did not have peelability. The peel strength at this time showed a high numerical value. In Comparative Example 5, since the heat seal layer is crystalline, heat seal can not be performed and evaluation can not be performed. Comparative Examples 6 and 7 used the test sample (II) and the test sample (III) and were shown to have no removability in such a case.

The test sample having the composition of the present invention is easy to peel because the sealant film does not break in the specific direction and the peelability is sufficient, and the peel strength is suitable for imparting easy peelability. It was shown to have excellent openability when

<Low adsorption evaluation>
Using the combination of laminates of Examples 1-15 and Comparative Examples 1-4, bag-like adsorptive test samples were prepared. Each package bag is first heat sealed on three sides so that the area of the bag excluding the heat seal portion is 5 cm square (contact area with the contents 50 cm ² ), and 500 mg of L-menthol is put from the opening. The opening was heat sealed and completely sealed to make an adsorptive test sample.

The adsorptive test samples were stored at 40 ° C. for 2 weeks. Thereafter, the adsorptive test sample was opened, L-menthol was removed from the bag, and physically attached L-menthol was completely removed by an air gun. Then, all of the adsorptive test samples were placed in a test tube, and 10 ml of methanol was used to extract L-menthol adsorbed on the sealant film. Each extract was subjected to gas chromatography analysis, and the adsorption amount of L-menthol adsorbed on the sealant film was calculated from a calibration curve prepared in advance. The calculated values were evaluated according to the following categories.

○: adsorption amount less than 1.0 mg / 50 cm ²
Δ: The adsorption amount is 1.0 mg or more / 50 cm ² , less than 3.0 mg / 50 cm ²
X: adsorption amount is 3.0 mg or more / 50 cm ²
The results are shown in Table 2. Examples 1-7, 10, 11, 13, 14 exhibited excellent low adsorption. Although Examples 8, 9 and 12 have low adsorptivity, the adsorption amount was larger than those of the other examples. This is considered to be due to the fact that the orientation crystallization of the layer to be laminated is insufficient and the amount of adsorption is large because it is a combination of relatively low draw ratios unlike the other examples. Example 15 is one in which the sealant film is not stretched in one of the laminate films. Therefore, although having low adsorptivity, the amount of adsorption was larger than in the other examples.

It is shown that Comparative Examples 1 to 3 have a large amount of adsorption and do not have low adsorption.

<Fuzz evaluation>
Using the test samples of Examples 1 to 15 and Comparative Examples 1 to 4, the state of the peeled surface after peeling was evaluated. The evaluation was carried out by visually observing the surface condition of the peeled surface, and the evaluation of fuzz was evaluated according to the following criteria.

:: no fuzzing, surface condition is fair :: some fuzzing occurs x: fuzzing on the entire surface The results are shown in Table 2. In Examples 10 to 12 in which the difference in draw ratio of the first and second sealant films is 0.1 or less, fuzz derived from the heat seal layer was slightly confirmed in the peeling surface. The cause is that the interlayer strength between the layer to be laminated and the heat seal layer is equal in the first and second sealant films, as shown in FIG. 9D, between the first sealant film and the second sealant film. At the same time, delamination occurs randomly, and at the same time, the heat seal layer also exfoliates while stretching.

On the other hand, in Examples 1 to 9 and 13 to 15 having a difference in draw ratio of 0.2 or more, as shown in FIG. 9C, selection is made in a sealant film having a higher draw ratio, that is, lower interlayer strength. Since delamination occurs in the heat seal layer, fuzzing of the heat seal layer does not occur, and a smooth release surface is obtained.

Comparative Example 2 has peelability due to peeling between the modified PE of the layer to be laminated and the heat seal layer, and the interlayer strengths of the first and second sealant films are equal, so delamination occurs randomly, resulting in Fuzz was slightly confirmed.

Comparative Example 4 did not have peelability because the sealant film was not stretched, so fuzz was observed on the peel surface. Comparative Example 3 has a large difference in draw ratio because the sealant film is not stretched in one of the laminate films. Therefore, it is considered that fuzz did not occur.

<Evaluation of productivity>
The productivity of Examples 1 to 15 and Comparative Examples 1 to 4 was evaluated. Evaluation was performed according to the following criteria.

:: no particular problem in all of resin production process, film forming process and bag-making process x: problem in any of resin production process, film-forming process and bag-making process No particular problems were observed, and the product had excellent productivity. In Example 13, since the NPG content of the first sealant film exceeds 40 mol%, the polymerization time for producing the resin becomes long, and there is a problem in the resin production process. In Example 14, since the ratio of the thickness of the layer to be laminated to the thickness of the heat seal layer is less than 3 times, the heat shrinkage behavior at the time of heat seal becomes large, and there is a problem in the bag manufacturing process. In Example 15, the second sealant film is not stretched, and the film forming speed is relatively lower than that of the stretched film, so there is a problem in the film forming process.

Claims (8)

A sealant film having easy peelability for laminates, comprising:
Having a layer to be laminated and a heat seal layer,
The to-be-laminated layer is made of a polyester resin having crystallinity as a main component,
The heat seal layer comprises an amorphous copolymer comprising a first dicarboxylic acid component and a first diol component as main components, and further comprising at least one of a second dicarboxylic acid component and a second diol component. Containing 50% by mass or more of the total mass of the heat seal layer,
A sealant film characterized by being uniaxially stretched in a manufacturing process. The first dicarboxylic acid component is a terephthalic acid component, the first diol component is an ethylene glycol component, the second diol component is a neopentyl glycol component, and the content of the neopentyl glycol component is The sealant film according to claim 1, which is in the range of 20 to 40% by mole based on the total diol component in the copolyester resin. The uniaxial stretching in the manufacturing process is performed at a stretching ratio of 3 to 5 times, the thickness of the heat seal layer after stretching is in the range of 1 to 5 μm, and the thicknesses of the layer to be laminated and the heat seal layer The sealant film according to claim 1 or 2, characterized in that the ratio of is in the range of 3: 1 to 8: 1. A heat-sealed easy peel packaging bag in which a first laminate material and a second laminate material are laminated and
The first laminate material comprises a first sealant film according to any one of claims 1 to 3 and a first base laminated to face the laminate layer of the first sealant film. Material film and
The second laminate material includes a to-be-laminated layer composed of a polyester resin having crystallinity as a main component, a first dicarboxylic acid component and a first diol component as main components, and a second dicarboxylic acid component and A non-crystalline copolyester resin containing at least one component of the second diol component at 50% by mass or more of the total mass of the heat seal layer, and a heat seal layer laminated on the laminate layer A second sealant film, and a second base film laminated to face the laminated layer of the second sealant film,
The first laminate material is bonded such that the heat seal layer faces the heat seal layer of the second laminate material,
An easy peel packaging bag, wherein the first sealant film is opened in a direction orthogonal to the uniaxially stretched direction. The second sealant film is uniaxially stretched in the manufacturing process, and the direction in which the first sealant film is uniaxially stretched is the same as the direction in which the second sealant film is uniaxially stretched. The easy-peel packaging bag according to claim 4, wherein the easy-peel packaging bag is laminated. The easy peel packaging bag according to claim 5, wherein the peel strength at the time of opening the easy peel packaging bag is in the range of 3 to 15 N / 15 mm width. The easy peel packaging bag according to claim 5, wherein the peel strength at the time of opening the easy peel packaging bag is in the range of 3 to 6 N / 15 mm width. The difference of the draw ratio of the draw ratio of said 1st sealant film and the draw ratio of said 2nd sealant film is 0.2 or more, It is characterized by the above-mentioned, Easy peel packaging bag.

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