JP2018034425A - Easily-openable stretched film and easily-openable laminate material prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily-openable stretched film that has excellent easily-openable and poorly-adsorbable properties.SOLUTION: An easily-openable stretched film contains a substrate layer containing a crystalline polyethylene terephthalate resin, and a seal layer provided on the substrate layer and containing an amorphous polyester resin having a glass transition temperature of 105°C-120°C.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an easy-open stretched film and an easy-open laminate material using the same.

  Containers made of polyester resins are widely used to store food, sundries and the like. When these containers need to be sealed, a laminate material having a container and a heat-sealing seal layer as a lowermost layer is used as a cover material, the container opening is covered with such a cover material, and the cover material is used as a container. Heat seal to the flange. The sealing container obtained in this way needs to peel off the lid when taking out the contents. For this reason, in addition to having a container and heat-sealability, the laminate material used as a lid | cover material is requested | required to have easy-open property (easy peel property).

  Patent Document 1 discloses an easy-open laminate film for a polyester resin container, which has a three-layer structure including a seal layer / a first base layer / a second base layer. In Patent Document 1, the seal layer is mainly composed of a mixture of a crystalline polyester having a glass transition temperature of 40 ° C. or lower and an amorphous polyester having a glass transition temperature of 45 ° C. to 75 ° C. The layer has acid-modified polyolefin as a main component, and the second base material layer has unmodified polyolefin as a main component. When the easy-open laminate film of Patent Document 1 is heat-sealed with another material and then peeled off from the other material, delamination occurs between the seal layer and the first base material layer, thereby making it easy to open. It is expressed.

  Patent Document 2 discloses an easy-open laminated film for a polyester resin container, which has a three-layer structure composed of a seal layer / adhesive resin layer / base material layer. In Patent Document 2, the seal layer is made of a mixture of an amorphous polyethylene terephthalate polymer (a1) and a polybutylene terephthalate homopolymer (a2), or an amorphous polyethylene terephthalate polymer (a1) and a polybutylene terephthalate system. A mixture with the copolymer (a3) or a single resin of (a3) is the main component, the adhesive resin layer is mainly composed of acid-modified polyolefin, and the base material layer is composed mainly of polyolefin. When the easy-open laminated film of Patent Document 2 is heat-sealed with another material and then peeled off from the other material, delamination occurs between the seal layer and the adhesive resin layer, thereby exhibiting easy-opening properties. Yes.

  In Patent Document 3, a sealing layer formed of a mixture obtained by adding an olefinic thermoplastic elastomer to a low crystalline polyester resin, and a base material layer made of polybutylene terephthalate resin, is easy for a polyester resin container. An openable laminated film is disclosed. In Patent Document 3, when the seal layer is composed of only a low crystalline polyester resin, a large opening strength is required at the time of opening. Therefore, by adding an olefin-based thermoplastic elastomer to the seal layer, easy opening is expressed. Yes.

  In this way, the conventional easy-open film for polyester resin containers is provided with a polyolefin resin layer as a layer adjacent to a seal layer made of polyester resin, or a polyolefin resin is added to the polyester resin layer of the seal layer In other words, easy opening was realized.

Japanese Patent No. 4601768 Japanese Patent No. 5182183 JP-A-5-229050

  When the present inventors use an easy-open film containing a polyolefin-based resin as a lid for a container that encloses a content containing a volatile fragrance component or a medicinal component, the easy-open film volatilizes over time. A problem has been found that the adsorbing of the sexual component reduces the content of the aromatic component or the medicinal component in the container.

  Therefore, an object of the present invention is to provide an easy-open film excellent in easy-openability and low adsorptivity, and an easy-open laminate material using the easy-open film.

According to one aspect of the invention,
A base material layer containing crystalline polyethylene terephthalate resin;
There is provided an easy-open stretched film that is provided on the base material layer and includes a sealing layer containing an amorphous polyester resin having a glass transition temperature of 105 ° C to 120 ° C.

According to another aspect of the invention,
The easy-open stretched film;
There is provided an easy-open laminate material including a base film provided on the base layer side of the easy-open stretched film.

  ADVANTAGE OF THE INVENTION According to this invention, the easily openable stretched film excellent in easy openability and low adsorptivity, and an easily openable laminate material using the same can be provided.

FIG. 1 is a schematic cross-sectional view of an easy-open stretched film of the present invention. FIG. 2 is a schematic cross-sectional view of a laminate material using the easy-open stretched film of the present invention. FIG. 3 is a schematic diagram showing how to evaluate peelability. FIG. 4 is a schematic cross-sectional view showing a sealed state of a container with a lid containing the laminate material of the present invention as a lid material. FIG. 5 is a schematic cross-sectional view showing an opened state of a container with a lid containing the laminate material of the present invention as a lid material. FIG. 6 is a schematic cross-sectional view showing an unsealed state of a lidded container including the comparative laminate material as a lid.

  The present invention will be described in detail below, but the following description is intended to explain the present invention in detail and is not intended to limit the present invention.

The easy-open stretched film of the present invention is
A base material layer containing crystalline polyethylene terephthalate resin;
A sealing layer provided on the base material layer and including an amorphous polyester resin having a glass transition temperature of 105 ° C. to 120 ° C.

The easy-open laminate material of the present invention is
An easy-open stretched film of the present invention;
And a base film provided on the base layer side of the easy-open stretched film.

  In a preferred embodiment, the easy-open laminate material of the present invention is used as a container lid. Specifically, the easy-open laminate material of the present invention can be heat-sealed with the upper end of the opening of the container body through a seal layer to form a sealed container. When such a sealed container is opened, delamination occurs between the seal layer and the base material layer, whereby easy-openability can be realized.

<Easily openable stretched film>
In FIG. 1, the cross-sectional schematic diagram of the easily openable stretched film 1 of this invention is shown. As shown in FIG. 1, the easy-open stretched film 1 of the present invention has a base material layer 3 and a seal layer 5 provided on the base material layer 3. The easy-open stretched film 1 of the present invention is produced by stretching a laminated film obtained by laminating a seal layer on a base material layer.

<Base material layer>
In the present invention, the base material layer contains a crystalline polyethylene terephthalate resin. Preferably, the base material layer contains a crystalline polyethylene terephthalate resin as a main component. Here, “comprising as a main component” means that the base material layer contains crystalline polyethylene terephthalate resin in an amount of 60 to 100% by weight, preferably 70 to 100% by weight, more preferably, based on the total weight of the base material layer. 80 to 100% by mass, more preferably 90 to 100% by mass, particularly preferably 99 to 100% by mass. “Crystallinity” means that, in differential scanning calorimetry (DSC), a peak (melting point) associated with crystal melting is observed in the range of 20 to 300 ° C. (temperature increase rate: 10 ° C./min.). Say. Polyethylene terephthalate resin having such crystallinity can be oriented and crystallized by stretching.

  The crystalline polyethylene terephthalate resin may be a non-modified crystalline polyethylene terephthalate resin or a modified crystalline polyethylene terephthalate resin. The modified crystalline polyethylene terephthalate resin is, for example, a modified crystalline polyethylene terephthalate resin having a modification rate of 10 mol% or less, and typically an isophthalic acid modified crystalline polyethylene having an isophthalic acid modification rate of 10 mol% or less. It is a terephthalate resin.

  The modified crystalline polyethylene terephthalate resin has a modification rate of, for example, 10 mol% or less, preferably 1 to 10 mol%. When the modified component is a dicarboxylic acid component, the “modified rate” refers to the mole percentage occupied by the modified component among all the dicarboxylic acid components contained in the crystalline polyethylene terephthalate resin. Similarly, when the modifying component is a diol component, the “modification rate” refers to the mole percentage occupied by the modifying component among all the diol components contained in the crystalline polyethylene terephthalate resin.

  In a preferred embodiment, the crystalline polyethylene terephthalate resin is an unmodified crystalline polyethylene terephthalate resin. In another preferred embodiment, the crystalline polyethylene terephthalate resin is an isophthalic acid modified crystalline polyethylene terephthalate resin having an isophthalic acid modification rate of 10 mol% or less, generally 1 to 10 mol%.

  Since a modifying component such as isophthalic acid lowers the melting point of the crystalline polyethylene terephthalate resin, the crystalline polyethylene terephthalate resin preferably contains a modifying component from the viewpoint of film forming property. However, when the modification rate is high, the crystallinity is lowered and the low adsorptivity is adversely affected. Therefore, it is preferable not to exceed 10 mol%. Moreover, the modified crystalline polyethylene terephthalate resin having such a low modification rate is excellent in economy because it is used in a large amount for general purposes including PET bottles.

  On the other hand, non-modified crystalline polyethylene terephthalate resin has the advantages of high crystallinity and excellent low adsorptivity compared to modified crystalline polyethylene terephthalate resin containing a modifying component such as isophthalic acid.

  From the above, since both the modified crystalline polyethylene terephthalate resin and the unmodified crystalline polyethylene terephthalate resin having a modification rate of 10 mol% or less have high crystallinity, they can be oriented and crystallized by stretching, and have low adsorptivity. Is excellent.

  In the easy-open stretched film of the present invention, the crystalline polyethylene terephthalate resin contained in the base material layer is oriented and crystallized by stretching, and the interlayer strength between the base material layer and the adjacent seal layer made of the amorphous polyester resin is increased. Reduce. Thereby, delamination occurs between the base material layer and the seal layer, and easy-openability is exhibited.

  The base material layer contains other resins as long as the crystalline polyethylene terephthalate resin is oriented and crystallized by stretching, and the interlaminar strength between the base material layer and the seal layer is lowered. Also good. The other resin is preferably a polyester-based resin from the viewpoint of low adsorptivity and film forming property of the easy-open stretched film.

  In addition, the base material layer is formed by using commonly used additives such as antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, flame retardants, inorganic fine particles, organic fine particles, and colorants as required An additive such as may be included.

<Sealing layer>
In the present invention, the seal layer contains an amorphous polyester resin having a glass transition temperature of 105 ° C to 120 ° C. Preferably, the sealing layer contains an amorphous polyester resin having a glass transition temperature of 105 ° C. to 120 ° C. as a main component. Here, “containing as a main component” means that the sealing layer has an amorphous polyester resin having a glass transition temperature of 105 ° C. to 120 ° C., preferably 50 to 100% by mass, preferably based on the total mass of the sealing layer. It represents that it contains in the quantity of 50-90 mass%, More preferably, it is 65-90 mass%, More preferably, it is 80-90 mass%. The term “amorphous” means that the crystal is in the range of 20 to 300 ° C. (temperature increase rate: 10 ° C./min.) In differential scanning calorimetry (DSC) even after the laminated film is stretched in the film forming process. This means that no peak (melting point) associated with melting is observed. Such an amorphous polyester resin does not cause orientation crystallization due to stretching, and thus has heat-sealing properties even after stretching.

  As the amorphous polyester resin contained in the sealing layer, any amorphous polyester resin can be used as long as it has a glass transition temperature of 105 ° C. to 120 ° C., for example, spiroglycol, isosorbide, or An amorphous polyester resin modified with a diol component such as TMCD (2,2,4,4-tetramethyl-1,3-cyclobutanediol) can be used.

  The amorphous polyester resin having a glass transition temperature of 105 ° C. to 120 ° C. is, for example, an amorphous polyethylene terephthalate resin modified with a diol component such as spiroglycol, isosorbide, or TMCD. Here, the amorphous polyethylene terephthalate resin modified with the diol component may contain an additional diol component such as 1,4-CHDM (1,4-cyclohexanedimethanol). Alternatively, an amorphous polyester resin having a glass transition temperature of 105 ° C. to 120 ° C. is obtained by, for example, amorphous poly-1,4-cyclohexylenedimethylene terephthalate modified with a diol component such as spiroglycol, isosorbide, or TMCD. Resin. Here, the amorphous poly-1,4-cyclohexylenedimethylene terephthalate resin modified with the diol component may contain an additional diol component such as ethylene glycol.

  If the glass transition temperature of the amorphous polyester resin is less than 105 ° C., delamination between the base material layer and the seal layer cannot be achieved, which is not preferable. Moreover, when the glass transition temperature of an amorphous polyester resin exceeds 120 degreeC, the temperature required for extending | stretching will become high and is not preferable at the point of film forming property. In addition, if the glass transition temperature of the amorphous polyester resin exceeds 120 ° C., it is necessary to increase the temperature at the time of heat sealing, and there is a possibility that the object to be heat-sheathed (for example, a polyester resin container) is deformed. Therefore, it is not preferable.

  More specifically, as the amorphous polyester resin, an amorphous polyester resin having a glass transition temperature of 105 to 120 ° C. prepared using any dicarboxylic acid component and any diol component can be used. Here, for the glass transition temperature of the resin, for example, an alicyclic diol component such as spiroglycol, isosorbide, TMCD (2,2,4,4-tetramethyl-1,3-cyclobutanediol) is used as a modifying component. Can be improved by. That is, the amorphous polyester resin can contain the above-described modifying component in such an amount that the resin can have a glass transition temperature of 105 to 120 ° C., for example, if it is a spiro glycol-modified polyethylene terephthalate resin, 35 Spiroglycol can be included at a modification rate of ˜50 mol%. Here, the “modification rate” refers to the mole percentage occupied by the modification component among all the diol components contained in the amorphous polyester resin. Thus, an amorphous polyester resin having a glass transition temperature of 105 to 120 ° C. can be prepared and used.

  Alternatively, as the amorphous polyester resin, a commercially available amorphous polyester resin having a glass transition temperature of 105 to 120 ° C. may be used. As such an amorphous polyester resin, for example, trade name: “ALTERSTER” (manufactured by Mitsubishi Gas Chemical Co., Ltd., spiroglycol-modified polyester resin), trade name: “ECOZEN” (manufactured by SK Chemical Co., Ltd., isosorbide) Modified polyester resin) and trade name: “TRITAN” (manufactured by EASTMAN Chemical Co., Ltd., TMCD modified polyester resin).

  In a preferred embodiment, the amorphous polyester resin contained in the seal layer has a glass transition temperature of 105 to 120 ° C., a spiroglycol modified amorphous polyester resin, an isosorbide modified amorphous polyester resin, or a TMCD modified amorphous polyester. Polyester resin. In a more preferred embodiment, the amorphous polyester resin contained in the seal layer is a spiro glycol-modified amorphous polyethylene terephthalate resin, isosorbide-modified amorphous polyethylene terephthalate resin, or TMCD-modified having a glass transition temperature of 105 to 120 ° C. Amorphous polyethylene terephthalate resin. Here, the amorphous polyethylene terephthalate resin modified with the diol component may contain an additional diol component such as 1,4-CHDM (1,4-cyclohexanedimethanol). Alternatively, in a more preferred embodiment, the amorphous polyester resin contained in the seal layer is a spiro glycol-modified amorphous poly-1,4-cyclohexylene dimethylene terephthalate resin or isosorbide having a glass transition temperature of 105 to 120 ° C. Modified amorphous poly-1,4-cyclohexylene dimethylene terephthalate resin or TMCD modified amorphous poly-1,4-cyclohexylene dimethylene terephthalate resin. Here, the amorphous poly-1,4-cyclohexylenedimethylene terephthalate resin modified with the diol component may contain an additional diol component such as ethylene glycol.

  In another preferred embodiment, the amorphous polyester resin contained in the sealing layer is an amorphous polyester resin having a glass transition temperature of 105 ° C to 115 ° C. In a more preferred embodiment, the amorphous polyester resin having a glass transition temperature of 105 ° C. to 115 ° C. is a spiro glycol-modified amorphous polyester resin, isosorbide-modified amorphous polyester resin, or TMCD-modified amorphous polyester resin. . In a more preferred embodiment, the amorphous polyester resin having a glass transition temperature of 105 ° C. to 115 ° C. is a spiro glycol-modified amorphous polyethylene terephthalate resin, an isosorbide-modified amorphous polyethylene terephthalate resin, or a TMCD-modified amorphous polyethylene terephthalate. Resin. Here, the amorphous polyethylene terephthalate resin modified with the diol component may contain an additional diol component such as 1,4-CHDM (1,4-cyclohexanedimethanol). Alternatively, in a further preferred embodiment, the amorphous polyester resin having a glass transition temperature of 105 ° C. to 115 ° C. is a spiro glycol-modified amorphous poly-1,4-cyclohexylenedimethylene terephthalate resin, isosorbide-modified amorphous poly 1,4-cyclohexylenedimethylene terephthalate resin or TMCD-modified amorphous poly-1,4-cyclohexylenedimethylene terephthalate resin. Here, the amorphous poly-1,4-cyclohexylenedimethylene terephthalate resin modified with the diol component may contain an additional diol component such as ethylene glycol.

  In another preferred embodiment, the amorphous polyester resin contained in the sealing layer is an amorphous polyester resin having a glass transition temperature of 110 ° C to 120 ° C. In a more preferred embodiment, the amorphous polyester resin having a glass transition temperature of 110 ° C. to 120 ° C. is a spiro glycol-modified amorphous polyester resin, an isosorbide-modified amorphous polyester resin, or a TMCD-modified amorphous polyester resin. . In a more preferred embodiment, the amorphous polyester resin having a glass transition temperature of 110 ° C. to 120 ° C. is a spiro glycol-modified amorphous polyethylene terephthalate resin, an isosorbide-modified amorphous polyethylene terephthalate resin, or a TMCD-modified amorphous polyethylene terephthalate. Resin. Here, the amorphous polyethylene terephthalate resin modified with the diol component may contain an additional diol component such as 1,4-CHDM (1,4-cyclohexanedimethanol). Alternatively, in a further preferred embodiment, the amorphous polyester resin having a glass transition temperature of 110 ° C. to 120 ° C. is a spiro glycol-modified amorphous poly-1,4-cyclohexylenedimethylene terephthalate resin, isosorbide-modified amorphous poly 1,4-cyclohexylenedimethylene terephthalate resin or TMCD-modified amorphous poly-1,4-cyclohexylenedimethylene terephthalate resin. Here, the amorphous poly-1,4-cyclohexylenedimethylene terephthalate resin modified with the diol component may contain an additional diol component such as ethylene glycol.

  The seal layer may contain other resins as long as easy-openability can be expressed. The other resin is preferably a polyester resin from the viewpoint of low adsorptivity and film forming property. As another resin, for example, a polyester resin having high compatibility with an amorphous polyester resin (main component) having a glass transition temperature of 105 ° C. to 120 ° C. and having a glass transition temperature lower than that of the main component can be used. As a result, the glass transition temperature can be lowered, and the stretchability and the low-temperature sealability can be improved.

  If necessary, the seal layer may be added with commonly used additives such as antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, flame retardants, inorganic fine particles, organic fine particles, and coloring agents. An agent may be included.

<Method for producing easy-open stretched film>
The crystalline polyethylene terephthalate resin constituting the base material layer and the non-crystalline polyester resin constituting the seal layer are commonly used polyester resin production methods such as direct esterification and transesterification. Can be manufactured by.

  The easy-open stretched film of the present invention can be produced by a known method. Specifically, the easy-open stretched film of the present invention can be produced by producing a laminated film having a two-layer structure and stretching the obtained laminated film.

  The laminated film can be produced, for example, by a coextrusion method. In the co-extrusion method, the resin that forms the base layer and the resin that forms the seal layer are melted in an extruder, merged and extruded in a T-die mold equipped with a multi-manifold system, and quickly cooled by a cooling roll. By doing so, a laminated film is manufactured. The obtained laminated film consists of a base material layer and a sealing layer laminated adjacent to the base material layer.

  Next, the obtained laminated film can be stretched to produce the easy-open stretched film of the present invention. The stretching may be uniaxial stretching or biaxial stretching. By stretching the laminated film, the crystalline polyethylene terephthalate resin of the base material layer is oriented and crystallized, so that the interlayer strength between the base material layer and the adjacent seal layer is reduced, and easy opening due to delamination can be expressed. . Moreover, low adsorptivity improves by extending | stretching.

<Stretching method and stretch ratio>
The easy-open stretched film of the present invention can be produced by any method of uniaxial stretching and biaxial stretching. The stretching is preferably performed in a temperature range of 110 to 130 ° C.

  In the production process of the easy-open stretched film of the present invention, a well-known method such as a roll method or a tenter method can be used as a method for uniaxially stretching a laminated film composed of a base material layer and a seal layer. Since the method of stretching due to the difference in peripheral speed between rolls is inexpensive as an apparatus, longitudinal uniaxial stretching by a roll method is more preferable. Longitudinal uniaxial stretching by a roll method is preferably performed in a temperature range of 110 to 130 ° C.

  Moreover, as a method of biaxially stretching a laminated film composed of a base material layer and a seal layer, any of sequential biaxial stretching and simultaneous biaxial stretching can be used. For example, a roll method and a tenter method are used. A combined sequential biaxial stretching method can be used. In sequential biaxial stretching, the film may be stretched in the longitudinal direction (MD) first and then in the transverse direction (TD), or may be stretched in the transverse direction and then stretched in the longitudinal direction. The sequential biaxial stretching is also preferably performed in a temperature range of 110 to 130 ° C.

  It is preferable that the draw ratio at the time of uniaxially stretching the laminated film is in the range of 2.0 to 5.0 times. The stretching ratio when biaxially stretching the laminated film is in the range of 2.0 to 5.0 times in the main stretching direction and in the range of 1.1 to 5.0 times in the direction orthogonal to the main stretching direction. It is preferable. Here, the main stretching direction refers to the higher stretching direction in the stretching ratio in the longitudinal direction and the transverse direction.

  The larger the draw ratio, the higher the crystallinity of the base material layer and the lower the adsorptivity. Moreover, the larger the draw ratio, the lower the interlayer strength between the base material layer and the seal layer, and the easier the opening. When the draw ratio is too low (for example, when the draw ratio of uniaxial stretching is less than 2.0 times), the interlayer strength between the base material layer and the seal layer is not sufficiently lowered, and the opening strength is increased. In addition, delamination may not occur stably, which is not preferable. On the other hand, when the stretch ratio is too high (for example, when the stretch ratio of uniaxial stretching exceeds 5.0 times), the interlayer strength between the base material layer and the seal layer is too low, and the opening strength is lowered. When used as a sealant film for a lid of a polyester resin container, there is a possibility that the sealing performance may be insufficient, which is not preferable.

<Thickness of easy-open stretched film>
In the easy-open stretched film of the present invention, the thickness of the seal layer is preferably in the range of 1 μm to 10 μm. When the thickness of the seal layer is less than 1 μm, stable heat seal strength may not be maintained. On the other hand, if the thickness of the seal layer exceeds 10 μm, the peel strength at the initial stage of opening (initial opening strength) increases, and it may be difficult to stably open the seal layer.

  The thickness of the easy-open stretched film is preferably in the range of 10 μm to 50 μm. When the thickness of the easy-open stretched film is less than 10 μm, it is easy to break during stretching and it is difficult to stably form a film. On the other hand, when the thickness of the easy-open stretched film exceeds 50 μm, in addition to being inferior in economic efficiency, the film may be stiff and handling properties may be deteriorated when the laminate material is processed.

<Laminate and lid material>
According to the present invention, a laminate material using the easy-open stretched film described above is provided. In FIG. 2, the cross-sectional schematic diagram of the laminate material 2 of this invention is shown. As shown in FIG. 2, the laminate material 2 includes a base film 7 and an easy-open stretched film 1 provided on the base film 7. In FIG. 2, the easy-open stretched film 1 has a base material layer 3 and a seal layer 5 provided on the base material layer 3.

  Although the base film 7 is not limited to these, a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyamide film, a biaxially stretched polypropylene film, or the like is preferably used.

  The base film 7 is laminated so as to face the base layer 3 of the easy-open stretched film 1. A barrier layer may be provided between the base film 7 and the base layer 3 as necessary. 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.

  Each of the easy-open stretched film, the base film and the barrier layer can be optionally bonded using an adhesive. As the adhesive, a known adhesive that can be used for adhesion of the resin film can be used, and it is appropriately selected depending on the components of the easy-open stretched film, the base film layer, and the barrier layer.

  In a preferred embodiment, the laminate material of the present invention is used as a container lid and an easy-open pouch. When a laminate material is used as a container lid (hereinafter also simply referred to as a lid), an appropriate shape can be selected in accordance with the shape of the container body, and processing such as punching and cutting can be performed. For example, when the shape of the container main body is a bottomed cylindrical shape, the lid member can be circular corresponding to the shape of the opening of the container main body. Such a circular lid member may have a knob portion protruding outward from the edge of the circular portion. Moreover, when using a laminate material as a cover material, you may have further a printing layer or a protective layer in the base film side of the laminate material.

  The lid material preferably has an opening strength (also referred to as peel strength) in the range of 3 to 15 N / 15 mm width, which is a standard for easy opening. More preferably, the peel strength is in the range of 8 to 13 N / 15 mm width. The peel strength can be set to a desired range by adjusting the stretch ratio of the easy-open stretched film.

  A container main body is comprised from arbitrary materials, for example, is comprised from a polyester-type resin. The container body has an arbitrary shape, for example, a bottomed cylinder or a bottomed rectangular tube.

  The container can be sealed by storing the contents in the container body and then heat-sealing the sealing layer of the laminate material of the present invention with the upper end of the opening of the container body. An example of a container with a lid containing the laminate material of the present invention as a lid material is shown in FIGS. FIG. 4 shows a sealed state of the lidded container, and FIG. 5 shows an opened state of the lidded container shown in FIG.

  In FIG. 4, the circular laminate material 2 covers the opening of the bottomed cylindrical container body 9 and functions as a lid material. The laminate material 2 has a knob portion 2a protruding outward from the edge of the circular portion. The laminate material 2 has a three-layer structure including a base film 7 / base material layer 3 / sealing layer 5. As shown in FIG. 4, the container main body 9 has a flange portion 9 a at the opening, and the seal layer 5 of the laminate material 2 is heat-sealed with the flange portion 9 a to seal the container.

  As shown in FIG. 5, when the user opens the container, if the user picks the tab 2a of the laminate material 2 and pulls the laminate material 2 upward, only the seal layer 5 is broken first, and then the seal layer 5 and the substrate Delamination occurs between the layers 3 and finally only the sealing layer 5 is broken again, whereby the container is opened.

  As described above, according to the present invention, easy-open stretch including a base material layer containing a crystalline polyethylene terephthalate resin and a seal layer containing an amorphous polyester resin having a glass transition temperature of 105 ° C. to 120 ° C. A film is provided. In the easy-open stretched film of the present invention, the crystalline polyethylene terephthalate resin of the base material layer is oriented and crystallized by stretching, so that the interlayer strength between the base material layer and the adjacent seal layer is lowered. As a result, easy-openability due to delamination between the base material layer and the seal layer can be expressed. In addition, the conventional easy-open film uses an acid-modified polyolefin-based resin in a layer adjacent to a sealing layer made of a polyester-based resin, whereas the easy-open stretched film of the present invention uses only a polyester-based resin. And since the easy-open property by delamination can be expressed, it is excellent in low adsorptivity.

  Therefore, the easy-open stretched film of the present invention has an effect that the contents can be easily taken out due to the easy-open property and an effect that it is difficult to adsorb the aromatic component and the medicinal component due to the low adsorptivity. Because of these effects, the laminate material produced using the easy-open stretched film of the present invention can be suitably used as a lid material for containers for housing foods, cosmetics, pharmaceuticals and the like.

1. Preparation of sealant film [Example 1]
Resin constituting a sealing layer using a copolymerized polyethylene terephthalate resin (Bell Polyester Products, Belpet PIFG5) (hereinafter referred to as IPET5) having a 5 mol% isophthalic acid modification rate as a resin constituting the base layer As a copolymer, a copolymerized polyethylene terephthalate resin (Mitsubishi Gas Chemical Co., Ltd., ALTERSTER S4500, glass transition temperature 110 ° C.) (hereinafter referred to as SPET45) having a spiro glycol modification rate of 45 mol% was used.

  IPET5 and SPET45 are coextruded at a temperature of 270 ° C. using a T-die mold so that the thickness of the base layer and the thickness of the seal layer are 48 μm and 12 μm, respectively, and quickly cooled by a cooling roll. Then, a two-layer laminated film was produced.

  Subsequently, the laminated film was heated to 120 ° C. and uniaxially stretched (longitudinal stretching) by a roll stretching method so that the total thickness of the film became 20 μm. The uniaxial stretching ratio was 3.0 times. After the longitudinal stretching, the film forming process was completed by quickly cooling with a cooling roll without performing so-called lateral stretching, performing corona treatment on the base material layer side, and winding it into a roll. This obtained the sealant film. The thickness of the base material layer and the seal layer of the obtained sealant film was 16 μm and 4 μm, respectively.

[Comparative Example 1]
A copolymer polyethylene terephthalate resin (IPET5) having an isophthalic acid modification rate of 5 mol% is used as the resin constituting the base layer, and a copolymer polyethylene terephthalate resin having a spiro glycol modification rate of 10 mol% is used as the resin constituting the seal layer. A sealant film was obtained under the same conditions as in Example 1 except that (Mitsubishi Gas Chemical Co., Ltd., ALTERSTER S1000, glass transition temperature 86 ° C.) (hereinafter, SPET10) was used.

[Comparative Example 2]
A copolymer polyethylene terephthalate resin (IPET5) having an isophthalic acid modification rate of 5 mol% is used as the resin constituting the base layer, and a copolymer polyethylene terephthalate resin having a spiro glycol modification rate of 20 mol% is used as the resin constituting the seal layer. A sealant film was obtained under the same conditions as in Example 1 except that Mitsubishi Gas Chemical Co., Ltd. (ALTERSTER S2000, glass transition temperature 95 ° C.) (hereinafter, SPET20) was used.

[Comparative Example 3]
A copolymer polyethylene terephthalate resin (IPET5) having an isophthalic acid modification rate of 5 mol% is used as the resin constituting the base layer, and a copolymer polyethylene terephthalate resin having a spiro glycol modification rate of 30 mol% is used as the resin constituting the seal layer. A sealant film was obtained under the same conditions as in Example 1 except that (Mitsubishi Gas Chemical Co., Ltd., ALTERSTER S3000, glass transition temperature 100 ° C.) (hereinafter, SPET30) was used.

[Comparative Example 4]
Polyethylene resin (Evolue SP2320, manufactured by Prime Polymer Co., Ltd.) (hereinafter referred to as PE) is used as the resin constituting the base material layer, and acid modification is used as the resin constituting the intermediate layer between the base material layer and the seal layer. Polyethylene resin (manufactured by Mitsui Chemicals, Admer SF725) (hereinafter referred to as M-PE) is used as a resin constituting the sealing layer, and a copolymerized polyethylene terephthalate resin (SK Chemical (30 mol%) having a cyclohexanedimethanol modification rate is used. Co., Ltd., Skygreen S2008) (hereinafter PETG) 55% by mass and isophthalic modification rate 30 mol% copolymer polybutylene terephthalate resin (Wintech Polymer Co., Ltd., Juranex 600LP) (hereinafter IBT30) 45% by mass (Hereinafter, PETG / IBT30).

  PE, M-PE, and PETG / IBT30 were coextruded using a T-die mold so that the base layer, intermediate layer, and seal layer had thicknesses of 15 μm, 10 μm, and 5 μm, respectively. It cooled with the cooling roll, the corona treatment was given to the base material layer side, it wound up in roll shape, and produced the three-layer sealant film.

  The sealant film of Comparative Example 4 corresponds to the easy-open laminated film described in Japanese Patent No. 5182183 described in the Background Art section.

2. Production of Laminate Material A laminate material was produced using each sealant film produced in Example 1 and Comparative Examples 1 to 4. Specifically, first, a biaxially stretched polyester (PET) film having a thickness of 12 μm and an aluminum foil having a thickness of 9 μm are dry-laminated using a two-component curable isocyanate adhesive to produce a base film. did. Next, the obtained base film and each sealant film are two-component curable isocyanate adhesives so that the surface of the base film on the aluminum foil side and the surface of the sealant film on the base material layer side face each other. The laminate was prepared by dry lamination using

3. Evaluation method
[Evaluation of peelability and measurement of peel strength]
The A-PET sheet having a thickness of 300 μm was made to face the sealing layer of the produced laminate material, and the A-PET sheet and the laminate material were heat-sealed at 180 ° C. for 1 second and allowed to cool. Thereafter, the obtained test sample was cut into a strip shape having a width of 15 mm to obtain a test sample piece.

  FIG. 3 schematically shows a method for evaluating peelability. As shown in FIG. 3, the test sample piece comprised from the laminate material 2 and the A-PET sheet 11 was attached to the grip portion 12 positioned above and below the tensile tester. In FIG. 3, the heat seal portion is shown as 5a. The test sample piece was pulled in the tensile direction indicated by the arrow in FIG. 3 with a tensile tester, and the laminate material 2 was peeled from the A-PET sheet 11.

  While peelability was evaluated according to the following criteria, peel strength was measured.

  When the laminate material 2 could be peeled off from the A-PET sheet 11 in the heat seal part 5a without breaking the sealant film, the evaluation result of peelability was evaluated as ◯. On the other hand, when the sealant film was broken at the start of peeling or in the middle of peeling, the evaluation result of peelability was taken as x. The fact that the sealant film breaks during peeling means that the sealant film cannot be used as a lid sealant film.

[Evaluation of adsorptivity]
Each sealant film produced in Example 1 and Comparative Example 4 was pasted with a two-component curable isocyanate adhesive so that the aluminum foil having a thickness of 20 μm and the base material layer of the sealant film and the aluminum foil faced each other. Combined. The obtained laminate film was cut into a 5 cm square, and the obtained film piece was sealed in a container containing 100 mg of L-menthol so that the film piece and menthol were not in direct contact. After storage at a temperature of 40 ° C. for 2 weeks, the amount of L-menthol adsorbed on the film piece (adsorption amount) was determined by the following formula.
Adsorption amount [g / m ² ] = {(mass of film piece after storage [g]) − (mass of film piece before storage [g])} × 400

4). Evaluation Results Table 1 shows the evaluation results of peelability and the measurement results of peel strength.

  In Example 1, the peelability of the laminate material with respect to the A-PET sheet was good, and it was confirmed that delamination occurred between the base material layer and the seal layer in the heat seal portion (peel portion). In Comparative Examples 1 to 3, the sealant film was broken during peeling.

  From these results, it can be seen that a sealant film including a base material layer containing a crystalline polyethylene terephthalate resin and a seal layer containing an amorphous polyester resin having a high glass transition temperature can realize good peelability.

  When the laminate material of Example 1 is used as a cover material of a container (for example, a polyester resin container), as shown in FIG. 5, excellent openability is exhibited when the container is opened. Specifically, as shown in FIG. 5, since the sealing layer 5 of the laminate material of Example 1 is completely bonded to the container body 9 by heat sealing, only the sealing layer 5 is first broken when the container is opened. Next, delamination occurs between the seal layer 5 and the base material layer 3, and finally only the seal layer 5 is broken again, whereby the container is opened and the contents can be taken out.

  On the other hand, the opening state of the container at the time of using the laminated material of Comparative Examples 1-3 as a cover material of a container (polyester-type resin container) is shown in FIG. As shown in FIG. 6, in the case of the laminate materials of Comparative Examples 1 to 3, since the base material layer 3 and the seal layer 5 are first broken simultaneously when the container is opened, the sealant film (reference numerals 3 and 5) Can't take out the contents that remain on top.

  Next, Table 2 shows the evaluation results of the adsorptivity.

  The sealant film of Example 1 had less L-menthol adsorption than the sealant film of Comparative Example 4. Since the sealant film of Example 1 is composed of only a polyester resin and does not use a polyolefin-based resin, it is presumed that the sealant film exhibited excellent low adsorptivity.

  DESCRIPTION OF SYMBOLS 1 ... Easy-open stretched film, 2 ... Laminate material, 2a ... Pick part, 3 ... Base material layer, 5 ... Seal layer, 5a ... Heat seal part, 7 ... Base film, 9 ... Container body, 9a ... Flange part DESCRIPTION OF SYMBOLS 10 ... Container with a lid, 11 ... A-PET sheet, 12 ... Grab part.

Claims (11)

A base material layer containing crystalline polyethylene terephthalate resin;
An easy-open stretched film including a sealing layer provided on the base material layer and containing an amorphous polyester resin having a glass transition temperature of 105 ° C to 120 ° C.   The easily openable stretched film according to claim 1, wherein the amorphous polyester resin is a spiro glycol-modified amorphous polyethylene terephthalate resin.   The easily openable stretched film according to claim 1 or 2, wherein the crystalline polyethylene terephthalate resin is a non-modified crystalline polyethylene terephthalate resin.   The easily openable stretched film according to claim 1 or 2, wherein the crystalline polyethylene terephthalate resin is an isophthalic acid-modified crystalline polyethylene terephthalate resin having an isophthalic acid modification rate of 10 mol% or less.   The easily openable stretched film according to any one of claims 1 to 4, wherein the easily openable stretched film is a uniaxially stretched film.   The easily openable stretched film according to claim 5, wherein the uniaxially stretched film is a film stretched at a stretch ratio of 2 to 5 times.   The easy-open stretched film according to any one of claims 1 to 6, wherein the seal layer has a thickness of 1 to 10 µm.   The easily openable stretched film according to any one of claims 1 to 7, wherein the easily openable stretched film has a thickness of 10 to 50 µm. The easy-open stretched film according to any one of claims 1 to 8,
An easy-open laminate material comprising a base film provided on the base layer side of the easy-open stretched film.   The easy-open laminate material according to claim 9, further comprising a barrier layer between the base material layer and the base material film.   The easy-open laminate material according to claim 9 or 10, which is a container lid.