JP2024009168A - bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bag having a puncture resistance and a heat resistance.

SOLUTION: A laminate constituting a bag having a steam release mechanism includes at least a first base material, a printed layer, a second base material, and a sealant layer in this order. The laminate includes a transparent vapor deposition layer provided on the first base material or the second base material between the first base material and the second base material, and a transparent gas barrier coating film provided on the transparent vapor deposition layer. One of the first base material and the second base material contains polyethylene terephthalate, and the other contains polybutylene terephthalate. Of the first base material and the second base material, the base material containing polybutylene terephthalate has a single-layer structure. The sealant layer is a single layer, the sealant layer includes polypropylene and polyethylene, polypropylene includes a propylene-ethylene block copolymer, and polyethylene is low density polyethylene or linear low density polyethylene. The puncture strength of the laminate is 13 N or higher.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a bag equipped with a steam release mechanism.

Conventionally, many bags made of plastic laminates are filled and sealed with cooked or semi-cooked liquid, viscous, or a mixture of liquid and solid contents on the market. In the bag, a non-sealed portion in which the laminates are not joined constitutes a storage portion in which the contents are stored. Further, the seal portion where the laminates are joined together seals the housing portion. The contents are, for example, cooked foods such as curry, stew, and soup. The contents are heated in the bag using a microwave oven or the like.

By the way, when the contents housed in a sealed bag are heated using a microwave oven, water contained in the contents evaporates as the contents are heated, increasing the pressure in the container. If the pressure in the bag storage area increases, there is a risk that the bag will burst and the contents will scatter, contaminating the inside of the microwave oven. In consideration of such issues, Patent Documents 1 to 3, for example, propose to provide a steam release mechanism that automatically connects the housing part with the outside and releases steam inside the housing part to the outside when the pressure in the housing part increases. is suggesting.

Japanese Patent Application Publication No. 10-95472 Japanese Patent Application Publication No. 2003-182780 Japanese Patent Application Publication No. 2008-308183

Laminated bodies for constructing bags are required to have so-called puncture resistance, which is a property that prevents the bag from tearing even when a sharp member with a pointed tip comes into contact with the bag. For this reason, conventional laminates include a film containing nylon having high puncture resistance, as disclosed in Patent Documents 1 and 2, for example. On the other hand, nylon easily absorbs moisture and has poor heat resistance. For example, as raised as a problem in Patent Document 3, when a bag made of a laminate including a nylon layer in the middle is heated in a microwave oven, holes may be formed in the nylon layer. In order to solve such problems, Patent Document 3 proposes that both the surface layer and the intermediate layer be made of polyethylene terephthalate (hereinafter also referred to as PET). However, it may be difficult to achieve sufficient puncture resistance with some PET.

An object of the present invention is to provide a bag that can effectively solve these problems.

The present invention provides a bag having a steam release mechanism, wherein the laminate forming the bag includes at least a first base material, a printed layer, a second base material, and a sealant layer in this order, and the laminate includes: A transparent vapor deposited layer provided on the first base material or the second base material between the first base material and the second base material, and a transparent gas barrier coating film provided on the transparent vapor deposited layer. , one of the first base material and the second base material contains 51% by mass or more of polyethylene terephthalate, and the other contains 51% by mass or more of polybutylene terephthalate, and the first base material The base material containing polybutyre terephthalate among the material and the second base material has a single layer structure, the sealant layer is a single layer, the sealant layer contains polypropylene and polyethylene, and the base material containing polybutyre terephthalate has a is a bag containing a propylene/ethylene block copolymer, the polyethylene being low density polyethylene or linear low density polyethylene, and the puncture strength of the laminate being 13N or more.

In the bag according to the present invention, the one of the first base material and the second base material that contains polybutylene terephthalate may contain 51% by mass or more of polybutylene terephthalate and polyethylene terephthalate. .

In the bag according to the present invention, the first base material may contain polyethylene terephthalate, and the second base material may contain polybutylene terephthalate. Alternatively, the first base material may contain polybutylene terephthalate, and the second base material may contain polyethylene terephthalate.

In the bag according to the present invention, the sealant layer may contain 80% by mass or more of polypropylene.

In the bag according to the present invention, the laminate further includes a first adhesive layer located between the first base material and the second base material and containing a cured product of a polyol and an aliphatic isocyanate compound. You can.

In the bag according to the present invention, the laminate may further include a second adhesive layer located between the second base material and the sealant layer and containing a cured product of a polyol and an aliphatic isocyanate compound. good.

According to the present invention, the bag can have puncture resistance and heat resistance.

It is a front view showing a bag in an embodiment of the present invention. FIG. 2 is a sectional view showing the bag shown in FIG. 1 taken along line II-II. It is a sectional view showing an example of the layer composition of the layered product which constitutes a bag. FIG. 3 is a cross-sectional view showing an example of the layer structure of the first film of the laminate. It is a figure which shows an example of the measuring method of puncture strength. 1 is a diagram showing the layer structure and evaluation results of Examples 1 to 4 and Comparative Examples 1 and 2. FIG. FIG. 7 is a cross-sectional view showing a modified example of the layer structure of the laminate. FIG. 7 is a cross-sectional view showing a modified example of the layer structure of the laminate.

An embodiment of the present invention will be described with reference to FIGS. 1 to 4. In addition, in the drawings attached to this specification, for convenience of illustration and ease of understanding, the scale and the vertical and horizontal dimension ratios are appropriately changed and exaggerated from those of the actual drawings.

In addition, terms such as "parallel," "orthogonal," and "identical" and values of length and angle used in this specification that specify shapes, geometric conditions, and their degrees must be strictly The term shall be interpreted to include the extent to which similar functions can be expected, without being bound by meaning.

FIG. 1 is a front view showing a bag 10 according to this embodiment. The bag 10 includes a storage section 17 that stores the contents. In addition, in FIG. 1, the bag 10 is shown in a state before it is filled with contents. The bag 10 according to this embodiment is configured so that it can be suitably used as a microwave pouch whose contents are heated in a microwave oven.

As shown in FIG. 1, the bag 10 according to the present embodiment includes a steam release mechanism 20 for releasing steam generated when heating the contents stored in the bag 10 to the outside. The steam venting mechanism 20 communicates the inside and outside of the bag 10 to release steam when the pressure of steam exceeds a predetermined value, and suppresses steam venting from locations other than the steam venting mechanism 20. So, it's configured. The configuration of the bag 10 will be described below.

Bag In this embodiment, the bag 10 is a gusset-type bag configured to be self-supporting. The bag 10 includes an upper part 11, a lower part 12, and a side part 13, and has a generally rectangular outline in a front view. In addition, names such as "upper part", "lower part", and "side part", and terms such as "upper part" and "lower part" are based on the state in which the bag 10 stands on its own with the gusset part facing down. It is merely a relative representation of the positions and directions of 10 and its constituent elements. The posture of the bag 10 during transportation or use is not limited by the names or terms used in this specification.

As shown in FIG. 1, the bag 10 includes a front film 14 constituting the front surface, a back film 15 constituting the back surface, and a lower film 16 constituting the lower part 12. The lower film 16 is placed between the front film 14 and the back film 15 in a folded state at the folded portion 16f.

Note that the terms "front film", "back film", and "lower film" mentioned above are merely divisions of each film according to the positional relationship, and the method of providing the film when manufacturing the bag 10 is It is not intended to be limited by the above terms. For example, the bag 10 may be manufactured using one film in which the front film 14, the back film 15, and the lower film 16 are arranged in series, or the bag 10 may be manufactured using one film in which the front film 14 and the lower film 16 are arranged in series. It may be manufactured using a total of two films, a film and one back film 15, or a total of three films, one front film 14, one back film 15, and one bottom film 16. It may be manufactured using

The inner surfaces of the front film 14, the back film 15, and the lower film 16 are joined to each other by a seal portion. In a plan view of the bag 10 such as in FIG. 1, the seal portion is hatched.

As shown in FIG. 1, the seal portion includes an outer edge seal portion extending along the outer edge of the bag 10 and a steam release seal portion 20a that constitutes the steam release mechanism 20. The outer edge seal portion includes a lower seal portion 12 a extending to the lower portion 12 and a pair of side seal portions 13 a extending along the pair of side portions 13 . In addition, in the bag 10 in a state before it is filled with contents, as shown in FIG. 1, the upper part 11 of the bag 10 is an opening 11b. After the contents are stored in the bag 10, the inner surface of the front film 14 and the inner surface of the back film 15 are joined at the upper portion 11, thereby forming an upper seal portion and sealing the bag 10.

The side seal portion 13a, the steam release seal portion 20a, and the upper seal portion are seal portions formed by joining the inner surface of the front film 14 and the inner surface of the back film 15.
On the other hand, the lower seal part 12a is formed by joining the inner surface of the front film 14 and the inner surface of the lower film 16, and by joining the inner surface of the back film 15 and the inner surface of the lower film 16. It includes a seal portion configured.

As long as the bag 10 can be sealed by joining opposing films together, there are no particular limitations on the method for forming the seal portion. For example, the sealed portion may be formed by melting the inner surfaces of the film by heating and welding the inner surfaces together, that is, by heat sealing. Alternatively, the seal portion may be formed by bonding the inner surfaces of opposing films together using an adhesive or the like.

Steam Venting Mechanism The configuration of the steam venting mechanism 20 will be described below. FIG. 2 is a sectional view showing the steam release mechanism 20 of the bag 10 shown in FIG. 1, taken along line II-II.

The steam venting seal portion 20a of the steam venting mechanism 20 has a shape that is easily peeled off as the pressure in the housing portion 17 increases. For example, the steam release seal portion 20a has a shape that protrudes toward the inside of the bag 10 from the side seal portion 13a. Thereby, the force applied to the steam release seal part 20a when the pressure in the accommodating part 17 increases can be made larger than the force applied to the side seal part 13a. Further, the width of the steam release seal portion 20a is smaller than the width of the side seal portion 13a. Further, as shown in FIGS. 1 and 2, a non-sealed portion 20b is formed between the steam release sealed portion 20a and the outer edge of the side portion 13. Thereby, communication between the accommodating portion 17 and the outside due to peeling of the seal portion can be made easier to occur in the steam release seal portion 20a than in the side seal portion 13a.

Layer structure of the front film and back film Next, the layer structure of the front film 14 and the back film 15 will be explained. FIG. 3 is a cross-sectional view showing a laminate 30 that constitutes the front film 14 and the back film 15.

As shown in FIG. 3, the laminate 30 includes at least a first film 40, a second film 50, and a third film 60 in this order. The first film 40 is located on the outer surface 30y side, and the third film 60 is located on the inner surface 30x side opposite to the outer surface 30y. The inner surface 30x is a surface located on the accommodating portion 17 side.

The first film 40 includes at least a first base material 41. Further, the first film 40 may further include a printed layer 42 located between the first base material 41 and the second base material 51. For example, the first film 40 may further include a printed layer 42 provided on the first base material 41. The second film 50 includes at least a second base material 51. The third film 60 includes at least a sealant layer 61. Further, the first film 40 and the second film 50 are bonded together by a first adhesive layer 45, and the second film 50 and the third film 60 are bonded by a second adhesive layer 55. Therefore, the laminate 30 according to the present embodiment includes, in order from the outer surface side to the inner surface side, a first base material / a printed layer / a first adhesive layer / a second base material / a second adhesive layer / a sealant layer. , it can be said. Note that "/" represents the boundary between layers.

The first film 40, first adhesive layer 45, second film 50, second adhesive layer 55, and third film 60 will be described in detail below.

(1st film)
In the example shown in FIG. 3, the first film 40 includes a first base material 41 that constitutes the outer surface 30y of the laminate 30, and a printed layer 42 provided on the inner surface 30x side of the first base material 41. The printed layer 42 is a layer printed on the first base material 41 in order to show product information or give aesthetic appearance to the bag 10. The printing layer 42 expresses characters, numbers, symbols, figures, patterns, etc. As the material constituting the printing layer 42, ink for gravure printing or ink for flexographic printing can be used. A specific example of the ink for gravure printing is Finart manufactured by DIC Graphics Corporation.

The first base material 41 contains polybutylene terephthalate (hereinafter also referred to as PBT) as a main component. For example, the first base material 41 contains 51% by mass or more of PBT. Hereinafter, the advantages of the first base material 41 containing PBT will be explained.

PBT has excellent dimensional stability and therefore excellent printability. Therefore, similarly to the case of polyethylene terephthalate (hereinafter also referred to as PET), the printing layer 42 can be provided on the first base material 41 containing PBT.

Furthermore, PBT has excellent heat resistance. Therefore, when the bag 10 is subjected to sterilization treatment such as boiling treatment or retort treatment, deformation of the first base material 41 or reduction in the strength of the first base material 41 can be suppressed. Retort processing is a process of filling the bag 10 with contents, sealing the bag 10, and then heating the bag 10 under pressure using steam or heated hot water. The temperature of the retort treatment is, for example, 120° C. or higher. The boiling process is a process of filling the bag 10 with contents, sealing the bag 10, and then boiling the bag 10 in hot water under atmospheric pressure. The temperature of the boiling treatment is, for example, 90°C or higher and 100°C or lower.
Moreover, since PBT has heat resistance, it is possible to suppress the first base material 41 from being stretched due to the pressure generated in the storage section 17 when the consumer heats the bag 10. Thereby, the pressure generated in the accommodating portion 17 can be effectively used as a force for peeling off the steam venting seal portion 20a of the steam venting mechanism 20. Therefore, during heating, the steam inside the housing section 17 can be released to the outside via the steam venting mechanism 20.

PBT also has high strength. For this reason, the bag 10 can be provided with puncture resistance, as in the case where the laminate forming the bag 10 includes nylon.

Furthermore, PBT has the property of being less likely to absorb moisture than nylon. Therefore, it is possible to prevent the first base material 41 from absorbing moisture and reducing the laminate strength of the laminate 30.

Hereinafter, the structure of the first base material 41 containing PBT will be described in detail. In this embodiment, as the configuration of the first base material 41 containing PBT, either the following first configuration or second configuration may be adopted.

[First configuration of first base material]
The content of PBT in the first base material 41 according to the first configuration is preferably 51% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 75% by mass or more, and most preferably Preferably it is 80% by mass or more. By setting the PBT content to 51% by mass or more, the first film 40 can have excellent impact strength and pinhole resistance.

The dicarboxylic acid component of PBT used as a main component is preferably 90 mol% or more of terephthalic acid, more preferably 95 mol% or more, still more preferably 98 mol% or more, and most preferably 100 mol% or more. It is mole%. The glycol component preferably contains 1,4-butanediol in an amount of 90 mol% or more, more preferably 95 mol% or more, even more preferably 97 mol% or more, and most preferably 1,4-butanediol during polymerization. No by-products other than those produced by the ether bond of butanediol are included.

The first base material 41 may contain polyester resin other than PBT. Thereby, for example, film formability when biaxially stretching the film-like first base material 41 and mechanical properties of the first base material 41 can be adjusted.
Examples of polyester resins other than PBT include polyester resins such as PET, polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and polypropylene terephthalate (PPT), as well as isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, and biphenyl dicarboxylic acid. , PBT resin copolymerized with dicarboxylic acids such as cyclohexanedicarboxylic acid, adipic acid, azelaic acid, and sebacic acid, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5 Examples include PBT resins in which diol components such as -pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, and polycarbonate diol are copolymerized.

The amount of polyester resin other than PBT added is preferably 49% by mass or less, more preferably 40% by mass or less. If the amount of polyester resin other than PBT exceeds 49% by mass, the mechanical properties of PBT may be impaired, and impact strength, pinhole resistance, and drawing formability may become insufficient.

The first base material 41 may contain, as an additive, a polyester-based or polyamide-based elastomer copolymerized with at least one of a flexible polyether component, polycarbonate component, and polyester component. Thereby, pinhole resistance during bending can be improved. The amount of additive added is, for example, 20% by mass. If the amount of the additive exceeds 20% by mass, the effect of the additive may be saturated or the transparency of the first base material 41 may decrease.

An example of a method for producing the film-like first base material 41 according to the first configuration will be described.
Here, a method for producing the film-like first base material 41 by a casting method will be described. More specifically, a method will be described in which resins having the same composition are formed into multiple layers during casting.

Since PBT has a fast crystallization speed, crystallization progresses even during casting. At this time, if a single layer is cast without multilayering, the crystals will grow to a large size because there is no barrier that can suppress crystal growth, and the resulting unstretched original fabric will be yield stress increases. For this reason, when biaxially stretching the unstretched original fabric, it becomes easy to break. Further, it is conceivable that the yield stress of the obtained biaxially stretched film becomes high and the formability of the biaxially stretched film becomes insufficient.
On the other hand, if the same resin is multilayered during casting, the stretching stress of the unstretched sheet can be reduced. Therefore, stable biaxial stretching becomes possible, and the yield stress of the obtained biaxially stretched film becomes low. This makes it possible to obtain a film that is flexible and has high breaking strength.

FIG. 4 is a cross-sectional view showing an example of the layer structure of the first film. When the first base material 41 is produced by multilayering and casting a resin, as shown in FIG. . Each of the plurality of layers 41a contains PBT as a main component. For example, each of the plurality of layers 41a preferably contains 51% by mass or more of PBT, more preferably 60% by mass or more of PBT. Note that among the plurality of layers 41a, the (n+1)th layer 41a is directly stacked on the nth layer 41a. That is, no adhesive layer or bonding layer is interposed between the plurality of layers 41a.

The reason why the properties of the PBT film are improved by multilayering is presumed as follows. When resins are laminated, even if the compositions of the resins are the same, interfaces between the layers exist, and crystallization is accelerated by the interfaces. On the other hand, the growth of large crystals beyond the layer thickness is suppressed.
Therefore, it is thought that the size of the crystals (spherulites) becomes smaller.

As a specific method for reducing the size of spherulites by multilayering, a general multilayering device (multilayer feed block, static mixer, multilayer multimanifold, etc.) can be used. For example, a method can be used in which thermoplastic resins sent out from different channels using two or more extruders are laminated in multiple layers using a feed block, static mixer, multi-manifold die, etc. . In addition, when multilayering resins of the same composition, it is also possible to use only one extruder and introduce the above-mentioned multilayering device into the melt line from the extruder to the die.

The first base material 41 has a multilayer structure including at least 10 layers 41a, preferably 60 layers or more, more preferably 250 layers or more, still more preferably 1000 layers or more. By increasing the number of layers, the size of spherulites in the unstretched original PBT can be reduced, and subsequent biaxial stretching can be stably performed. Furthermore, the yield stress of PBT in the form of a biaxially stretched film can be reduced. Preferably, the diameter of spherulites in the unstretched original PBT is 500 nm or less.

When biaxially stretching an unstretched PBT film to produce a biaxially stretched film, the stretching temperature (hereinafter also referred to as MD stretching temperature) in the longitudinal stretching direction (hereinafter referred to as MD) is preferably 40°C or higher. The temperature is more preferably 45°C or higher. By setting the MD stretching temperature to 40° C. or higher, it is possible to suppress the film from breaking. Further, the MD stretching temperature is preferably 100°C or lower, more preferably 95°C or lower. By setting the MD stretching temperature to 100° C. or lower, it is possible to suppress the phenomenon that orientation of the biaxially stretched film does not occur.

The stretching ratio in MD (hereinafter also referred to as MD stretching ratio) is preferably 2.5 times or more. This makes it possible to orient the biaxially stretched film and achieve good mechanical properties and a uniform thickness. The MD stretching ratio is, for example, 5 times or less.

The stretching temperature (hereinafter also referred to as TD stretching temperature) in the transverse stretching direction (hereinafter also referred to as TD) is preferably 40° C. or higher. By setting the TD stretching temperature to 40° C. or higher, it is possible to prevent the film from breaking. Further, the TD stretching temperature is preferably 100°C or less. By setting the TD stretching temperature to 100° C. or lower, it is possible to suppress the phenomenon that orientation of the biaxially stretched film does not occur.

The stretching ratio in TD (hereinafter also referred to as TD stretching ratio) is preferably 2.5 times or more. This makes it possible to orient the biaxially stretched film and achieve good mechanical properties and a uniform thickness. The MD stretching ratio is, for example, 5 times or less.

The TD relaxation rate is preferably 0.5% or more. Thereby, it is possible to suppress the occurrence of breakage during heat setting of the biaxially stretched PBT film. Further, the TD relaxation rate is preferably 10% or less. Thereby, it is possible to suppress the occurrence of thickness unevenness due to sagging in the biaxially stretched PBT film.

The thickness of the layer 41a of the first base material 41 shown in FIG. 4 is preferably 3 nm or more, more preferably 10 nm or more. Further, the thickness of the layer 41a is preferably 200 nm or less, more preferably 100 nm or less.
Moreover, the thickness of the first base material 41 is preferably 9 μm or more, more preferably 12 μm or more. Moreover, the thickness of the first base material 41 is preferably 25 μm or less, more preferably 20 μm or less. By setting the thickness of the first base material 41 to 9 μm or more, the first base material 41 has sufficient strength. Further, by setting the thickness of the first base material 41 to 25 μm or less, the first base material 41 exhibits excellent moldability. Therefore, the process of manufacturing the bag 10 by processing the laminate 30 including the first base material 41 can be efficiently carried out.

[Second configuration of first base material]
The first base material 41 according to the second configuration is made of a single layer film containing polyester whose main repeating unit is butylene terephthalate. For example, the first base material 41 mainly contains 1,4-butanediol or its ester-forming derivative as a glycol component, and terephthalic acid or its ester-forming derivative as a dibasic acid component. Contains homo- or copolymer-type polyesters obtained by condensation. The content of PBT in the first base material 41 according to the second configuration is preferably 51% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, Most preferably it is 90% by mass or more. Moreover, it is preferable that the first base material 41 according to the second configuration is composed of only polybutylene terephthalate and additives.

In order to impart mechanical strength to the first base material 41, PBT must have a melting point of 200° C. or more and 250° C. or less, and an IV value (intrinsic viscosity) of 1.10 dl/g or more and 1.35 dl/g or less. Preferably. Furthermore, those having a melting point of 215° C. or more and 225° C. or less and an IV value of 1.15 dl/g or more and 1.30 dl/g or less are particularly preferable. These IV values may be satisfied by the entire material constituting the first base material 41. The IV value can be calculated based on JIS K 7367-5:2000.

The first base material 41 according to the second configuration may contain a polyester resin other than PBT, such as PET, in a range of 30% by mass or less. When the first base material 41 contains PET in addition to PBT, PBT crystallization can be suppressed and the stretching processability of the PBT film can be improved. As the PET to be mixed with the PBT of the first base material 41, polyester having ethylene terephthalate as a main repeating unit can be used. For example, a homotype mainly composed of ethylene glycol as a glycol component and terephthalic acid as a dibasic acid component can be preferably used. In order to impart good mechanical strength properties, it is preferable to use PET with a melting point of 240° C. or more and 265° C. or less, and an IV value of 0.55 dl/g or more and 0.90 dl/g or less. Furthermore, those having a melting point of 245° C. or more and 260° C. or less and an IV value of 0.60 dl/g or more and 0.80 dl/g or less are particularly preferred.
By controlling the blending amount of PET to 30% by mass or less, it is possible to prevent the rigidity of the unstretched original fabric and the stretched film from becoming too high. This can prevent the stretched film from becoming brittle and reducing its pressure strength, impact strength, puncture strength, etc. Moreover, it is possible to suppress the occurrence of stretching failures when stretching an unstretched original fabric.

The first base material 41 may include a lubricant, an anti-blocking agent, an inorganic filler, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a plasticizer, a coloring agent, a crystallization inhibitor, and a crystallization inhibitor, as necessary. It may also contain additives such as accelerators. In addition, the polyester resin pellets used as the raw material for the first base material 41 have a moisture content of 0.05% by weight or less, preferably 0.01% by weight, before heating and melting, in order to avoid a decrease in viscosity due to hydrolysis during heating and melting. % or less before use.

An example of a method for producing the film-like first base material 41 according to the second configuration will be described.

In order to stably produce the film of the first base material 41 having the above-mentioned structure, it is important to suppress the growth of crystals in the state of the unstretched original film. Specifically, when an extruded PBT-based melt is cooled to form a film, the crystallization temperature range of the polymer is cooled at a certain rate or higher, that is, the cooling rate of the original fabric becomes an important factor. The cooling rate of the original fabric is, for example, 200° C./second or more, preferably 250° C./second or more, particularly preferably 350° C./second or more. Since the unstretched original fabric formed at a high cooling rate maintains a low crystalline state, the stability of bubbles during stretching is improved. Furthermore, since high-speed film formation becomes possible, film productivity also improves. When the cooling rate is less than 200° C./sec, it is thought that the crystallinity of the obtained unstretched original fabric becomes high and the drawability decreases. Furthermore, in extreme cases, the stretching bubble may burst and the stretching may not continue.

The unstretched original fabric containing PBT as a main component is preferably transported to a space where biaxial stretching is performed while maintaining the ambient temperature at 25° C. or lower, preferably at 20° C. or lower. Thereby, even if the residence time becomes long, the crystallinity of the unstretched original fabric immediately after film formation can be maintained.

The biaxial stretching method for obtaining a stretched film by stretching an unstretched original film is not particularly limited. For example, by tubular method or tenter method, the longitudinal direction and the transverse direction may be stretched simultaneously, or the longitudinal direction and the transverse direction may be stretched sequentially. Among these, the tubular method is particularly preferably employed because it can produce a stretched film with good balance of physical properties in the circumferential direction.

In the tubular method, an unstretched original fabric introduced into a stretching space is passed between a pair of low-speed nip rolls, and then heated with a stretching heater while forcing air into the roll. After the stretching is completed, air is blown onto the stretched film by a cooling shoulder air ring. In consideration of stretching stability, strength properties, transparency, and thickness uniformity of the stretched film, the stretching ratio is preferably 2.7 times or more and 4.5 times or less in MD and TD, respectively. By setting the stretching ratio to 2.7 times or more, sufficient tensile modulus and impact strength of the stretched film can be ensured. In addition, by setting the stretching ratio to 4.5 times or less, it is possible to suppress the occurrence of excessive strain on the molecular chains due to stretching, and to suppress the occurrence of breaks and punctures during the stretching process, thereby stabilizing the stretched film. It can be made into

The stretching temperature is preferably 40°C or higher and 80°C or lower, particularly preferably 45°C or higher and 65°C or lower. Since the unstretched original fabric produced at the above-mentioned high cooling rate has low crystallinity, the unstretched original fabric can be stably stretched even if the stretching temperature is relatively low. Further, by setting the stretching temperature to 80° C. or lower, shaking of the stretching bubbles can be suppressed and a stretched film with good thickness accuracy can be obtained. Further, by setting the stretching temperature to 40° C. or higher, it is possible to suppress occurrence of excessive stretching orientation crystallization due to low-temperature stretching and prevent whitening of the film.

The first base material 41 produced as described above is composed of, for example, a single layer containing polyester whose main repeating unit is butylene terephthalate. According to the above-mentioned production method, since the unstretched original fabric is formed into a film at a high cooling rate, even when the unstretched original fabric is composed of a single layer, a low crystalline state can be maintained. Therefore, the unstretched original fabric can be stretched stably.

(First adhesive layer)
The first adhesive layer 45 includes a first adhesive for bonding the first film 40 and the second film 50 together. Examples of the first adhesive include ether-based two-component reactive adhesives, ester-based two-component reactive adhesives, and the like.

Examples of the ether-based two-component reactive adhesive include polyether polyurethane. Polyether polyurethane is a cured product produced by the reaction of a polyether polyol as a main ingredient and an isocyanate compound as a curing agent. Isocyanate compounds include aromatic isocyanate compounds such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), etc. or adducts or multimers of the various isocyanate compounds mentioned above can be used.

Examples of the ester-based two-part reactive adhesive include polyester polyurethane and polyester. Polyester polyurethane is a cured product produced by the reaction of a polyester polyol as a main ingredient and an isocyanate compound as a curing agent. Examples of the isocyanate compound are the same as those for the ether-based two-component reactive adhesive described above.

(Second film)
The second film 50 includes at least a second base material 51. The second base material 51 contains PET as a main component. For example, the second base material 51 contains 51% by mass or more of PET. Since the second base material 51 contains PET, the second base material 51 can have heat resistance. For example, the melting point of the second base material 51 is higher and the hygroscopicity of the second base material 51 is lower than when the second base material 51 contains nylon. Thereby, when the bag 10 is heated in a microwave oven, it is possible to suppress holes from forming in the second base material 51 due to overheated water or the like. Further, the heat resistance of PET is higher than that of PBT. Therefore, according to this embodiment, the heat resistance of the laminate 30 can be improved even compared to the case where the second base material 51 is made of PBT. Thereby, for example, when the bag 10 is heated in a microwave oven and the temperature of the contents becomes high, it is possible to prevent the laminate 30 from being damaged and the performance of the laminate 30 from decreasing.

The thickness of the second base material 51 is preferably 9 μm or more, more preferably 12 μm or more. Further, the thickness of the second base material 51 is preferably 25 μm or less, more preferably 20 μm or less. By setting the thickness of the second base material 51 to 9 μm or more, the second base material 51 has sufficient strength. Further, by setting the thickness of the second base material 51 to 25 μm or less, the second base material 51 exhibits excellent moldability. Therefore, the process of manufacturing the bag 10 by processing the laminate 30 can be carried out efficiently.

(Second adhesive layer)
The second adhesive layer 55 includes a second adhesive for bonding the second film 50 and the third film 60 together. An example of the second adhesive is an ether-based two-component reactive adhesive. Examples of the ether-based two-component reactive adhesive include polyurethane, as in the case of the first adhesive. Polyurethane is a cured product produced by the reaction of a polyol as a main ingredient and an isocyanate compound as a curing agent. Note that as the polyol, polyether polyols and polyester polyols can be used, but it is preferable to use polyester polyols.

As the isocyanate compound, as mentioned above, there are aromatic isocyanate compounds and aliphatic isocyanate compounds. Among these, aromatic isocyanate compounds elute components that cannot be used in food applications in high-temperature environments such as heat sterilization. By the way, the second adhesive layer 55 is in contact with the third film 60, as shown in FIG. Therefore, when the second adhesive layer 55 contains an aromatic isocyanate compound, components eluted from the aromatic isocyanate compound may adhere to the contents of the bag 10 configured by the laminate 30.

In consideration of these issues, the second adhesive constituting the second adhesive layer 55 is a cured product produced by the reaction of a polyol as a main ingredient and an aliphatic isocyanate compound as a curing agent. I suggest using it. This can prevent components that cannot be used in food applications due to the second adhesive layer 55 from adhering to the contents.

In addition, in the case where the second film 50 does not have barrier properties such as gas barrier properties, and in the case where the first adhesive layer 45 described above contains an aromatic isocyanate compound, eluted from the aromatic isocyanate compound. It is also possible that the components adhere to the contents. In this case, as in the case of the second adhesive layer 55, as the first adhesive constituting the first adhesive layer 45, the polyol as the main ingredient and the aliphatic isocyanate compound as the curing agent react with each other. It is preferable to use a cured product produced by.

(3rd film)
The third film 60 includes at least a sealant layer 61 that constitutes the inner surface 30x of the laminate 30. As the material constituting the sealant layer 61, one or more resins selected from polyethylene such as low-density polyethylene, linear low-density polyethylene, and polypropylene can be used. The sealant layer 61 may be a single layer or a multilayer. Further, the sealant layer 61 is preferably made of an unstretched film. Note that "unstretched" is a concept that includes not only a film that has not been stretched at all, but also a film that has been slightly stretched due to the tension applied during film formation.

As described above, the bag 10 made of the laminate 30 is subjected to sterilization treatment such as boiling treatment or retort treatment at high temperature. Therefore, the sealant layer 61 used has heat resistance that can withstand these high-temperature treatments.

The melting point of the material constituting the sealant layer 61 is preferably 150°C or higher, more preferably 160°C or higher. By increasing the melting point of the sealant layer 61, the bag 10 can be retorted at a high temperature, and therefore the time required for the retort treatment can be shortened. Note that the melting point of the material constituting the sealant layer 61 is lower than the melting point of the resin constituting the first base material 41 and the melting point of the resin constituting the second base material 51.

When considering from the viewpoint of retort processing, a material containing propylene as a main component can be used as the material constituting the sealant layer 61. Here, the material "having propylene as a main component" means a material having a propylene content of 90% by mass or more. Specific examples of materials containing propylene as a main component include polypropylene such as propylene/ethylene block copolymer, propylene/ethylene random copolymer, homopolypropylene, or a mixture of polypropylene and polyethylene. Can be done. Here, "propylene/ethylene block copolymer" means a material having the structural formula shown in the following formula (I). Moreover, "propylene/ethylene random copolymer" means a material having a structural formula shown in the following formula (II). Moreover, "homopolypropylene" means a material having a structural formula shown in the following formula (III).

When a mixture of polypropylene and polyethylene is used as the material whose main component is propylene, the material may have a sea-island structure. Here, the "sea-island structure" refers to a structure in which polyethylene is discontinuously dispersed within a continuous region of polypropylene.

When considering from the viewpoint of boiling processing, examples of the material constituting the sealant layer 61 include polyethylene, polypropylene, or a combination thereof. Examples of polyethylene include medium density polyethylene, linear low density polyethylene, and combinations thereof. For example, it is also possible to use the materials mentioned above as materials constituting the sealant layer from the viewpoint of the above-mentioned retort processing. The material constituting the sealant layer has a melting point of, for example, 100°C or higher, more preferably 105°C or higher, and still more preferably 110°C or higher. When polyethylene is used as the material constituting the sealant layer, a melting point of 100° C. or higher can be achieved, for example, when the density of the polyethylene is 0.920 g/cm ³ or higher. Further, specific examples of the sealant film for forming the sealant layer having a melting point of 100° C. or higher include TUX-HC manufactured by Mitsui Chemicals Tohcello, L6101 manufactured by Toyobo, and LS700C manufactured by Idemitsu Unitec. A specific example of a sealant film for forming a sealant layer having a melting point of 105° C. or higher includes NB-1 manufactured by Tamapori. Specific examples of the sealant film for constituting the sealant layer having a melting point of 110° C. or higher include LS760C manufactured by Idemitsu Unitec and TUX-HZ manufactured by Mitsui Chemicals Tohcello.

Preferably, sealant layer 61 includes a propylene-ethylene block copolymer. For example, the third film 60 including the sealant layer 61 is an unstretched film containing a propylene/ethylene block copolymer as a main component. By using the propylene/ethylene block copolymer, the impact resistance of the third film 60 can be increased, and thereby the bag 10 can be prevented from being torn due to impact when dropped. Further, the puncture resistance of the laminate 30 can be improved.

Moreover, the sealant layer 61 may further contain a thermoplastic elastomer. By using a thermoplastic elastomer, the impact resistance and puncture resistance of the third film 60 can be further improved.

The thermoplastic elastomer is, for example, a hydrogenated styrene thermoplastic elastomer. The hydrogenated styrenic thermoplastic elastomer has a structure consisting of a polymer block A mainly composed of at least one vinyl aromatic compound and a polymer block B mainly composed of at least one hydrogenated conjugated diene compound. . Further, the thermoplastic elastomer may be an ethylene/α-olefin elastomer. Ethylene/α-olefin elastomer is a low-crystalline or amorphous copolymer elastomer, and is a random copolymer of 50 to 90% by mass of ethylene as the main component and α-olefin as a comonomer. be.

The content of the propylene/ethylene block copolymer in the sealant layer 61 is, for example, 80% by mass or more, and preferably 90% by mass or more.

A method for producing a propylene/ethylene block copolymer includes a method of polymerizing raw materials such as propylene and ethylene using a catalyst. As the catalyst, a Ziegler-Natta type catalyst, a metallocene catalyst, or the like can be used.

The thickness of the sealant layer 61 is preferably 30 μm or more, more preferably 40 μm or more. Further, the thickness of the sealant layer 61 is preferably 100 μm or less, more preferably 80 μm or less.

Layer Structure of Lower Film Next, the layer structure of the lower film 16 will be explained.

The layer structure of the lower film 16 is arbitrary as long as it has an inner surface that can be joined to the inner surface of the front film 14 and the inner surface of the back film 15. For example, similarly to the front film 14 and the back film 15, the above-mentioned laminate 30 may be used as the lower film 16. Alternatively, a film whose inner surface is composed of a sealant layer and whose structure is different from that of the laminate 30 may be used as the lower film 16.

Method for manufacturing the first film Next, an example of a method for manufacturing the first film 40 will be described.

First, a resin material containing PBT as a main component is prepared. Subsequently, a film-like first base material 41 is produced by extruding the resin material by a melt extrusion method such as a casting method or a tubular method. Subsequently, a printing layer 42 is formed on the first base material 41. In this way, the first film 40 including the first base material 41 and the printed layer 42 can be obtained.

Method for manufacturing a laminate Next, an example of a method for manufacturing the laminate 30 will be described.

First, the above-described first film 40 and second film 50 are prepared. Subsequently, the first film 40 and the second film 50 are laminated with the first adhesive layer 45 interposed therebetween by a dry lamination method. Thereafter, a laminate including the first film 40 and the second film 50 and the third film 60 are laminated with the second adhesive layer 55 interposed therebetween by a dry lamination method. Thereby, a laminate 30 including the first film 40, the second film 50, and the third film 60 can be obtained.

Alternatively, first the second film 50 and the third film 60 are laminated via the second adhesive layer 55, and then the first film 40 and the laminate including the second film 50 and the third film 60 are laminated together. The laminate 30 may be manufactured by laminating one adhesive layer 45 in between.

Method for manufacturing a bag A front film 14 and a back film 15 made of the above-described laminate 30 are prepared. Further, a folded lower film 16 is inserted between the front film 14 and the back film 15. Subsequently, the inner surfaces of each film are heat-sealed to form seal parts such as the lower seal part 12a and the side seal part 13a. Further, the films bonded together by heat sealing are cut into an appropriate shape to obtain the bag 10 shown in FIG. 1. Subsequently, the contents 18 are filled into the bag 10 through the opening 11b of the upper part 11. The content 18 is, for example, a cooked food containing water, such as curry, stew, or soup. In addition to foods, the bag 10 can also contain items that can be heated by boiling water or the like. Thereafter, the upper portion 11 is heat-sealed to form an upper sealed portion. In this way, a sealed bag 10 containing the contents 18 can be obtained.

Method for heating the contents Next, an example of a method for heating the contents 18 contained in the bag 10 will be described.

First, the bag 10 is placed inside a microwave oven with the lower part 12 facing down and the bag 10 standing on its own. Next, heat the contents using a microwave oven. As a result, the temperature of the contents 18 increases, and accordingly, the water contained in the contents 18 evaporates, and the pressure in the storage section 17 increases. When the pressure in the accommodating part 17 increases, the front film 14 and the back film 15 swell outward due to the force received from the accommodating part 17. In this embodiment, the laminate 30 that constitutes the front film 14 and the back film 15 includes a first base material 41 containing PBT as a main component. Therefore, the rigidity of the first base material 41 is high, and as a result, when the front film 14 and the back film 15 receive force, the first base material 41 in the front film 14 and the back film 15 is prevented from stretching. Can be suppressed. Thereby, the force generated due to the pressure generated in the housing section 17 can be mainly used as a force for peeling off the steam release seal section 20a, rather than as a force for stretching the front film 14 and back film 15. can. Therefore, the force applied to the steam release seal portion 20a can be increased. As a result, the steam release seal portion 20a is easily peeled off during heating, and the steam in the accommodating portion 17 can be released to the outside via the steam release mechanism 20.

In addition, the following effects can be achieved by the laminate 30 that constitutes the front film 14 and the back film 15 of the bag 10 including the first base material 41 whose main component is PBT.
First, PBT has excellent printability. Therefore, similarly to the case of polyethylene terephthalate (hereinafter also referred to as PET), the printing layer 42 can be provided on the first base material 41 containing PBT.
Furthermore, PBT has excellent heat resistance. Therefore, when the bag 10 is subjected to boiling treatment or retort treatment, it is possible to prevent the first base material 41 from being deformed or the strength of the first base material 41 from decreasing.
PBT also has high strength. Therefore, the puncture strength of the laminate 30 and the bag 10 can be increased, as in the case where the laminate forming the bag 10 includes nylon. The puncture strength of the laminate 30 is preferably 13N or more, more preferably 15N or more, and even more preferably 17N or more. The method for measuring puncture strength will be described in Example 1 below. PBT also has a property of being less likely to absorb moisture than nylon. Therefore, even if the first base material 41 containing PBT is placed on the outer surface 30y of the laminate 30, the first base material 41 absorbs moisture and the laminate strength of the laminate 30 decreases. can be suppressed.

Furthermore, since the laminate 30 constituting the front film 14 and the back film 15 of the bag 10 includes the second base material 51 mainly composed of PET, compared to the case where the second base material 51 is made of PBT, The heat resistance of the laminate 30 can be improved. This prevents the surface film 14 and the back film 15 from being damaged and the performance of the front film 14 and the back film 15 from decreasing when the temperature of the contents increases, for example, by heating the bag 10 in a microwave oven. can do.

Further, according to this embodiment, the sealant layer 61 of the laminate 30 that constitutes the front film 14 and the back film 15 of the bag 10 contains a propylene-ethylene block copolymer.
Therefore, the impact resistance and puncture resistance of the bag 10 can be improved.

Note that various changes can be made to the embodiments described above. Modifications will be described below with reference to the drawings as necessary. In the following description and the drawings used in the following description, the same reference numerals as those used for corresponding parts in the above-described embodiment are used for parts that can be configured similarly to the above-described embodiment, Omit duplicate explanations. Furthermore, if it is clear that the effects obtained in the above-described embodiment can also be obtained in the modified example, the explanation thereof may be omitted.

(Modified example of layer structure)
In the present embodiment described above, the first base material 41 contains 51% by mass or more of PBT, and the second base material 51 contains 51% by mass or more of PET, thereby improving the puncture resistance and heat resistance of the laminate 30. An example of how to increase the However, the invention is not limited to this, and the first base material 41 contains 51% by mass or more of PET, and the second base material 51 contains 51% by mass or more of PBT, thereby improving the puncture resistance and heat resistance of the laminate 30. You can increase your sexuality. As the PBT of the second base material 51, PBT according to the first configuration or PBT according to the second configuration described in connection with the first base material 41 described above can be used.

The fact that the second base material 51 contains 51% by mass or more of PBT and the first base material 41 contains 51% by mass or more of PET also contributes to improving the dimensional stability and printability of the laminate 30.

Further, both the first base material 41 and the second base material 51 may contain 51% by mass or more of PBT. As the PBT in this case, the PBT according to the first configuration or the PBT according to the second configuration explained in connection with the first base material 41 described above can be used.

Examples of combinations of materials constituting the first base material 41 and the second base material 51 are summarized in Table 1. In Table 1, the expression "PBT" means that 51% by mass or more of PBT is contained in the resin constituting the film of the first base material 41 or the second base material 51. Moreover, in Table 1, the notation "PET" means that 51% by mass or more of PET is contained in the resin constituting the film of the first base material 41 or the second base material 51.

Further, in the present embodiment described above, an example is shown in which the printed layer 42 is provided on the inner surface 30x side of the first base material 41, but the present invention is not limited to this, and the printed layer 42 is provided on the outer surface 30y side of the first base material 41. A printed layer 42 may be provided on the surface. Furthermore, the first base material 41 does not need to be provided with the printing layer 42 .

Further, a transparent vapor deposition layer 36 made of a transparent inorganic material is provided on the first base material 41 and/or the second base material 51 at a position between the first base material 41 and the second base material 51. You can leave it there. The transparent vapor deposition layer 36 may be provided on the inner surface 30x side of the first base material 41, as shown in FIG. 7, and on the outer surface 30y side of the second base material 51, as shown in FIG. may be provided. Further, a transparent gas barrier coating film 37 may be provided on the transparent vapor deposition layer 36.

The transparent vapor deposition layer 36 functions as a layer having a gas barrier function that prevents permeation of oxygen gas, water vapor, and the like. Note that two or more transparent vapor deposition layers 36 may be provided. When there are two or more transparent vapor deposited layers 36, they may have the same composition or different compositions. Examples of the method for forming the transparent vapor deposition layer 36 include a physical vapor deposition method (PVD method) such as a vacuum evaporation method, a sputtering method, and an ion plating method, or a plasma chemical vapor deposition method. Examples include chemical vapor deposition methods (CVD methods) such as thermal chemical vapor deposition methods and photochemical vapor deposition methods. Specifically, a vapor deposition layer can be formed on a film forming roller using a roller type vapor deposition film forming apparatus.

The transparent vapor deposition layer 36 is made of a transparent inorganic material such as aluminum oxide (aluminum oxide) or silicon oxide. As the transparent vapor deposition layer 36, it is preferable to use an amorphous thin film of aluminum oxide. Specifically, the transparent vapor deposition layer 36 is an amorphous thin film of aluminum oxide represented by the formula AlOX (where X represents a number in the range of 0.5 to 1.5). The transparent vapor deposition layer 36 can be an amorphous thin film of aluminum oxide in which the value of X decreases in the depth direction from the film surface toward the inner surface. An amorphous thin film of aluminum oxide is represented by the formula AlOX (wherein, It is preferable that the value of X increases. In addition, as the value of X in the above formula, a value of X = 0.5 or more can be used, but if Since the properties are poor, it is preferable to use one with X=1.0 or more. Moreover, since the material with X=1.5 is in a state where Al and oxygen are completely oxidized, the material up to the upper limit of X=1.5 can be used. Note that when the value of X in the above formula is 0, it is a complete inorganic substance (pure substance) and is not transparent.

Note that the rate of decrease in the value of This can be confirmed by performing elemental analysis of the transparent vapor deposited layer 36 using an analysis method such as ion etching.

The transparent vapor deposition layer 36 may be a layer made of a mixture of inorganic compounds containing covalent bonds between aluminum atoms and carbon atoms. In this case, the transparent vapor deposited layer 36 has a peak measured by ion etching in the depth direction using an X-ray photoelectron spectrometer (measurement conditions: X-ray source AlKα, X-ray output 120 W). It shows the presence of a bond, and may also have transparency and gas barrier properties that prevent the permeation of oxygen, water vapor, and the like.

A covalent bond between a metal atom and a carbon atom may be formed at the interface between the transparent vapor deposition layer 36 and the first base material 41 or the second base material 51. For example, when the transparent vapor deposition layer 36 contains aluminum oxide, covalent bonds between aluminum atoms and carbon atoms are formed at the interface between the first base material 41 or the second base material 51 and the transparent vapor deposition layer 36. can do. A covalent bond can be detected by measurement using X-ray photoelectron spectroscopy (hereinafter abbreviated as "XPS measurement").

In addition, in the transparent vapor deposition layer 36, the abundance ratio of covalent bonds between aluminum atoms and carbon atoms is observed when the interface between the transparent vapor deposition layer 36 and the first base material 41 or the second base material 51 is measured by XPS measurement. It is preferable that the amount is in the range of 0.3% or more and 30% or less of the total bonds containing carbon atoms. This strengthens the adhesion between the transparent vapor deposited layer 36 and the first base material 41 or the second base material 51, provides excellent transparency, and provides a gas barrier vapor deposited film with well-balanced performance.

If the abundance ratio of covalent bonds between aluminum atoms and carbon atoms is less than 0.3%, the adhesion of the transparent vapor deposition layer 36 will be insufficiently improved, making it difficult to maintain stable barrier properties.

Furthermore, the AL (aluminum)/O (oxygen) ratio of the transparent vapor deposited layer 36 containing aluminum oxide as a main component is lower than the first base material 41 or the second base material 51 and the transparent vapor deposited layer 36 It is preferably 1.0 or less within a range of up to 3 nm toward the surface of the transparent vapor deposition layer 36 on the side opposite to the base material 41 or the second base material 51.
Within the range from the interface between the transparent vapor deposited layer 36 and the first base material 41 or the second base material 51 to the surface of the transparent vapor deposited layer 36 on the opposite side to the first base material 41 or the second base material 51, the AL When the ratio of transparency is reduced.

The thickness of the transparent vapor deposition layer 36 is, for example, 30 Å or more and 150 Å. If it is less than 30 Å, gas barrier properties may become insufficient even when the transparent gas barrier coating film 37 is used in combination. On the other hand, if it exceeds 150 Å, the gas barrier performance of the laminate 30 may not be maintained. Although the reason for this is not clear, when the thickness of the transparent vapor deposited layer 36 exceeds 150 Å, the flexibility of the laminate 30 decreases, and when the laminate 30 is used for the bag 10, a portion of the transparent vapor deposited layer 36 may crack or It is thought that pinholes are generated and the gas barrier properties are deteriorated. The thickness of the transparent vapor deposition layer 36 is preferably 40 Å or more and 130 Å or less, more preferably 50 Å or more and 120 Å or less. The thickness of the transparent vapor deposition layer 36 can be measured by a fundamental parameter method using, for example, a fluorescent X-ray analyzer (product name: RIX2000 model, manufactured by Rigaku Corporation). Further, the thickness of the transparent vapor deposition layer 36 can be changed by changing the deposition rate of the transparent vapor deposition layer 36, by changing the vapor deposition rate, or the like.

When forming the transparent vapor deposition layer 36 on the first base material 41 or the second base material 51, the surface of the first base material 41 or the second base material 51 is subjected to pretreatment such as corona discharge treatment, flame treatment, plasma treatment, etc. You can also apply it. In particular, when forming a covalent bond between a metal atom and a carbon atom at the interface between the transparent vapor deposition layer 36 and the first base material 41 or the second base material 51, the first base material on which the transparent vapor deposition layer 36 is to be formed is Preferably, the surface of the material 41 or the second base material 51 is subjected to pretreatment. When the pretreatment is plasma treatment, the pretreatment device supplies plasma to the surface of the first base material 41 or the second base material 51 in a reduced pressure environment of 0.1 Pa or more and 100 Pa or less. Plasma uses an inert gas such as argon alone or a mixture of oxygen, nitrogen, carbon dioxide, or one or more of these gases as a plasma source gas, and the plasma source gas is excited by a potential difference caused by a high-frequency voltage or the like. It can be generated by doing this.

The pretreatment allows plasma to be confined near the surface of the first base material 41 or the second base material 51. As a result, the surface shape, chemical bonding state, and functional groups of the first base material 41 or the second base material 51 are changed, and the chemical properties of the surface of the first base material 41 or the second base material 51 are changed. It can be changed. This makes it possible to improve the adhesion between the first base material 41 or the second base material 51 and the transparent vapor deposition layer 36.

The transparent gas barrier coating film 37 is a layer that functions as a layer that suppresses permeation of oxygen gas, water vapor, and the like. The transparent gas barrier coating film 37 has a general formula R ¹ _n M(OR ² ) _m (wherein, R ¹ and R ² represent an organic group having 1 to 8 carbon atoms, and M represents a metal atom. , n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the valence of M.) and polyvinyl alcohol as described above. A transparent gas barrier composition containing a sol-based resin and/or an ethylene-vinyl alcohol copolymer, and further polycondensed by a sol-gel method in the presence of a sol-gel method catalyst, an acid, water, and an organic solvent. can get.

As the alkoxide represented by the above general formula R ¹ _n M(OR ² ) _m , at least one of a partial hydrolyzate of an alkoxide and a condensate of hydrolysis of an alkoxide can be used. In addition, the partial hydrolyzate of the alkoxide described above does not necessarily have to have all the alkoxy groups hydrolyzed, and may be one in which one or more alkoxy groups have been hydrolyzed, or a mixture thereof. As the condensate of alkoxide hydrolysis, a dimer or more of partially hydrolyzed alkoxide, specifically a dimer to hexamer, is used.

In the alkoxide represented by the above general formula R ¹ _n M(OR ² ) _m , silicon, zirconium, titanium, aluminum, and the like can be used as the metal atom represented by M. Preferred metals include, for example, silicon and titanium. Furthermore, in the present invention, alkoxides can be used alone or in combination of two or more alkoxides of different metal atoms in the same solution.

Further, in the alkoxide represented by the above general formula R ¹ _n M (OR ² ) _m , specific examples of the organic group represented by R ¹ include, for example, a methyl group, an ethyl group, an n-propyl group, an i Examples include alkyl groups such as -propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-hexyl group, n-octyl group, and others. Further, in the alkoxide represented by the above general formula R ¹ _n M(OR ² ) _m , specific examples of the organic group represented by R ² include, for example, a methyl group, an ethyl group, an n-propyl group, an i -propyl group, n-butyl group, sec-butyl group, and others. Note that these alkyl groups in the same molecule may be the same or different.

When preparing the above transparent gas barrier composition, for example, a silane coupling agent or the like may be added. As the silane coupling agent, known organoalkoxysilanes containing organic reactive groups can be used. In particular, organoalkoxysilanes having epoxy groups are preferably used, specifically, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, or β-(3, 4-epoxycyclohexyl)ethyltrimethoxysilane and the like can be used. The above silane coupling agents may be used alone or in combination of two or more.

(Modified example of bag)
In the present embodiment described above, an example was shown in which the bag 10 is a gusset type bag, but the specific configuration of the bag 10 is not particularly limited. For example, the bag 10 may be a so-called pillow bag, which is produced by forming a seal on the back so that one laminate has a cylindrical shape. Furthermore, the bag 10 may be a four-sided sealed bag or a three-sided sealed bag.

Furthermore, in the present embodiment described above, an example is shown in which the steam venting mechanism 20 is configured by the steam venting seal portion 20a having a shape protruding toward the inside of the bag 10 from the side seal portion 13a. However, the specific configuration of the steam venting mechanism 20 is not particularly limited as long as the steam in the storage section 17 can be appropriately discharged to the outside. For example, when the bag 10 is a pillow bag, the steam release mechanism 20 may be configured by a part of the back sticker, as in the case of Patent Document 1 mentioned above.

(Other aspects)
Another aspect of the present invention is a bag having a steam release mechanism, wherein the laminate constituting the bag includes at least a first base material, a second base material, and a sealant layer in this order, and the first base material Of the material and the second base material, one contains polyethylene terephthalate, the other contains polybutylene terephthalate, and the other of the first base material and the second base material contains 51% by mass or more of polyester. Contains butylene terephthalate and has a multilayer structure containing 10 or more layers, or has a single layer structure, and the IV value of polybutylene terephthalate is 1.10 dl/g or more and 1.35 dl/g or less , is a bag.

In the bag according to the present invention, preferably the laminate has a puncture strength of 13N or more.

In the bag according to the present invention, the laminate includes a transparent vapor deposited layer provided on the first base material or the second base material between the first base material and the second base material; It may further include a transparent gas barrier coating film provided on the vapor deposition layer. In this case, the transparent vapor deposition layer may contain aluminum oxide, and a covalent bond between an aluminum atom and a carbon atom may be formed at an interface between the first base material or the second base material and the transparent vapor deposition layer. .

In the bag according to the present invention, the laminate may further include a printed layer located between the first base material and the second base material.

In the bag according to the present invention, the first base material includes polyethylene terephthalate,
The second base material may contain polybutylene terephthalate. Alternatively, the first base material may contain polybutylene terephthalate, and the second base material may contain polyethylene terephthalate.

In the bag according to the present invention, the sealant layer may contain 90% by mass or more of polypropylene.

In the bag according to the present invention, the laminate further includes a first adhesive layer located between the first base material and the second base material and containing a cured product of a polyol and an aliphatic isocyanate compound. You can.

In the bag according to the present invention, the laminate may further include a second adhesive layer located between the second base material and the sealant layer and containing a cured product of a polyol and an aliphatic isocyanate compound. good.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist thereof.

(Example 1)
A film-like first base material 41 including the plurality of layers 41a and manufactured by a casting method as described in the above-described first configuration was prepared. The content of PBT in each layer 41a was 80%, the number of layers 41a was 1024, and the thickness of the first base material 41 was 15 μm. Subsequently, a printing layer 42 was formed on the film-like first base material 41 using Finart manufactured by DIC Graphics Corporation.

Further, a second film 50 in the form of a film including a second base material 51 was prepared. As the second base material 51, one containing 100% by mass of PET was used. The thickness of the second base material 51 was 12 μm.

Further, a film-like third film 60 including a sealant layer 61 was prepared. As the sealant layer 61, unstretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. was used. The thickness of the sealant layer 61 was 60 μm.

Next, the first film 40 and the second film 50 were laminated via the first adhesive layer 45 by a dry lamination method. As the first adhesive layer 45, a two-component polyurethane adhesive (base resin: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. RU-40 includes polyester polyol. H-4 contains an aliphatic isocyanate compound. The thickness of the first adhesive layer 45 was 3 μm.

Next, the laminate of the first film 40 and the second film 50 and the third film 60 were laminated by a dry lamination method to obtain a laminate 30. As the second adhesive layer 55, similarly to the first adhesive layer 45, a two-component polyurethane adhesive (base material: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. The thickness of the second adhesive layer 55 was 3 μm.

Subsequently, the puncture strength of the laminate 30 was measured in accordance with JIS Z1707 7.4. As a measuring instrument, Tensilon universal material testing machine RTC-1310 manufactured by A&D was used.
Specifically, as shown in FIG. 5, a semicircular needle 70 with a diameter of 1.0 mm and a tip radius of 0.5 mm is inserted from the outer surface 30y side into a test piece of the laminate 30 in a fixed state. was pierced at a speed of 50 mm/min (50 mm per minute), and the maximum value of stress until the needle 70 penetrated the laminate 30 was measured. The maximum value of stress was measured for five or more test pieces, and the average value was taken as the puncture strength of the laminate 30. The environment during measurement was a temperature of 23° C. and a relative humidity of 50%. As a result, the puncture strength was 17N.

Subsequently, a bag 10 was produced using the laminate 30, and the vapor permeability of the bag 10 was evaluated. Specifically, first, the bag 10 shown in FIG. 1 was produced using the laminate 30. The length S1 of the bag 10 was 145 mm, and the length S2 was 140 mm. Thereafter, 100 g of water was filled inside the bag 10, and the upper part 11 was heat-sealed to form an upper sealed part. Subsequently, the contents were heated for 1 minute using a microwave oven with an output of 1600 W, and it was determined whether holes were formed in the laminate 30 and whether the steam vent seal portion 20a of the steam vent mechanism 20 was properly peeled off. I checked to see if it was. As a result, no holes were formed in the laminate 30. Further, the steam release seal portion 20a was peeled off, and the steam inside the housing portion 17 was able to escape to the outside. That is, the evaluation results of both heat resistance and vapor permeability were good.

(Example 2)
The first base material 41 of the first film 40 contains 100% by mass of PBT, as described in the second configuration above, has a melting point of PBT of 224° C., an IV value of 1.26 dl/g, and is a tubular material. A laminate 30 was produced in the same manner as in Example 1, except that a single layer film produced by the method was used. The first base material 41 was a single layer film composed of only PBT and additives, and the thickness of the first base material 41 was 15 μm.

Subsequently, in the same manner as in Example 1, the puncture strength of the laminate 30 was measured. As a result, the puncture strength was 17N. Further, in the same manner as in Example 1, the heat resistance and vapor permeability of the bag 10 produced using the laminate 30 were evaluated. As a result, both the evaluation results of heat resistance and vapor permeability were good.

(Example 3)
Example 1 except that PBT constituting the first base material 41 of Example 1 was used as the second base material 51 and PET constituting the second base material 51 of Example 1 was used as the first base material 41. A laminate 30 was produced in the same manner as in Example 1.

Subsequently, in the same manner as in Example 1, the puncture strength of the laminate 30 was measured. As a result, the puncture strength was 17N. Further, in the same manner as in Example 1, the heat resistance and vapor permeability of the bag 10 produced using the laminate 30 were evaluated. As a result, both the evaluation results of heat resistance and vapor permeability were good.

(Example 4)
Example 2 except that PBT constituting the first base material 41 of Example 2 was used as the second base material 51 and PET constituting the second base material 51 of Example 2 was used as the first base material 41. A laminate 30 was produced in the same manner as in Example 1.

Subsequently, in the same manner as in Example 1, the puncture strength of the laminate 30 was measured. As a result, the puncture strength was 17N. Further, in the same manner as in Example 1, the heat resistance and vapor permeability of the bag 10 produced using the laminate 30 were evaluated. As a result, both the evaluation results of heat resistance and vapor permeability were good.

(Comparative example 1)
A laminate 30 was produced in the same manner as in Example 1, except that a base material containing 100% by mass of PET was used as the first base material 41 of the first film 40. The thickness of the first base material 41 was 12 μm.

Subsequently, in the same manner as in Example 1, the puncture strength of the laminate 30 was measured. As a result, the puncture strength was 12N. Further, in the same manner as in Example 1, the heat resistance and vapor permeability of the bag 10 produced using the laminate 30 were evaluated. As a result, both the heat resistance and vapor permeability evaluation results were good.

(Comparative example 2)
A laminate 30 was produced in the same manner as in Comparative Example 1, except that a 15 μm thick nylon film (Bonyl W manufactured by Kojin Holdings Co., Ltd.) was used as the second base material 51 of the second film 50. .

Subsequently, in the same manner as in Example 1, the puncture strength of the laminate 30 was measured. As a result, the puncture strength was 17N. Further, in the same manner as in Example 1, the heat resistance and vapor permeability of the bag 10 produced using the laminate 30 were evaluated. As a result, holes were formed in the laminate 30.
Further, it was not possible to peel off the steam vent seal portion of the steam vent mechanism. That is, the evaluation results of both heat resistance and vapor permeability were bad.

The layer structures and evaluation results of the laminates of Examples 1 to 4 and Comparative Examples 1 and 2 are collectively shown in FIG. In FIG. 6, in the "layer structure" column, the constituent elements of the laminate excluding the adhesive layer are listed in order from the top, starting from the outer layer. As can be seen from the comparison between Examples 1 to 4 and Comparative Example 1, since the first base material 41 or the second base material 51 contains PBT, both the first base material 41 and the second base material 51 contain PET. It was possible to achieve higher puncture strength than in the case where it was included. Further, as can be seen from the comparison between Examples 1 to 4 and Comparative Example 2, by using a material other than nylon as the second base material 51, specifically PBT or PET, the second base material 51 contains nylon. It was possible to achieve better heat resistance and vapor permeability than in the case of the conventional method.

10 Bag 11 Upper part 11a Upper sealed part 12 Lower part 12a Lower sealed part 13 Side part 13a Side sealed part 14 Front film 15 Back film 16 Lower film 17 Storage part 18 Contents 20 Steam venting mechanism 20a Steam venting sealed part 20b Non-sealed part 30 Laminate 40 First film 41 First base material 41a Layer 42 Print layer 45 First adhesive layer 50 Second film 51 Second base material 55 Second adhesive layer 60 Third film 61 Sealant layer 70 Needle

Claims (7)

A bag having a steam release mechanism,
The laminate constituting the bag includes at least a first base material, a printed layer, a second base material, and a sealant layer in this order,
The laminate includes a transparent vapor deposited layer provided on the first base material or the second base material between the first base material and the second base material, and a transparent vapor deposited layer provided on the transparent vapor deposited layer. Further comprising a gas barrier coating film,
One of the first base material and the second base material contains 51% by mass or more of polyethylene terephthalate, and the other contains 51% by mass or more of polybutylene terephthalate,
Of the first base material and the second base material, the base material containing polybutyreterephthalate has a single layer structure,
The sealant layer is a single layer,
The sealant layer includes polypropylene and polyethylene,
The polypropylene includes a propylene/ethylene block copolymer,
The polyethylene is low density polyethylene or linear low density polyethylene,
A bag, wherein the laminate has a puncture strength of 13N or more. The bag according to claim 1, wherein the one of the first base material and the second base material that contains polybutylene terephthalate contains 51% by mass or more of polybutylene terephthalate and polyethylene terephthalate. The first base material contains 51% by mass or more of polyethylene terephthalate,
The bag according to claim 1 or 2, wherein the second base material contains 51% by mass or more of polybutylene terephthalate. The first base material contains 51% by mass or more of polybutylene terephthalate,
The bag according to claim 1 or 2, wherein the second base material contains 51% by mass or more of polyethylene terephthalate. The bag according to any one of claims 1 to 4, wherein the sealant layer contains 80% by mass or more of polypropylene. The laminate further comprises a first adhesive layer located between the first base material and the second base material and containing a cured product of a polyol and an aliphatic isocyanate compound. The bag described in any one of the items. Any one of claims 1 to 6, wherein the laminate further comprises a second adhesive layer located between the second base material and the sealant layer and containing a cured product of a polyol and an aliphatic isocyanate compound. The bag described in paragraph 1.