JP7124285B2 - Laminate and bag composed of the laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminate and a bag composed of the laminate.

BACKGROUND ART Conventionally, many bags made of plastic laminates filled and sealed with cooked or semi-cooked liquids, viscous substances, or mixtures of liquids and solids have been on the market. In the bag, the non-sealed portion where the laminated bodies are not joined constitutes the storage portion in which the contents are stored. Moreover, the sealing portion where the stacked bodies are joined together seals the accommodating portion. The contents are, for example, cooked foods such as curries, stews, soups, or semi-cooked foods that are cooked by being heated. Heating is performed, for example, by boiling the contents together with the bag.

A laminate that constitutes a bag is required to have various properties such as heat resistance to withstand heat treatment and impact resistance to withstand impact when the bag is dropped. In consideration of these points, Patent Document 1, for example, proposes using a laminate comprising a polybutylene terephthalate layer/deposited film/adhesive layer/sealant layer in this order from the outer surface side to the inner surface side. there is Note that "/" represents a boundary between layers. The adhesive layer is a layer for laminating two films. For example, a PBT film forming a polybutylene terephthalate (hereinafter also referred to as PBT) layer and provided with a deposited film and a sealant film forming a sealant layer are laminated by a dry lamination method via an adhesive layer. there is

JP 2014-15233 A

As described above, the laminate described in Document 1 has a two-layer structure including two films, a base layer and a sealant layer. When the laminate has a two-layer structure, there is a problem that the bag is easily broken when dropped.

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

The present invention is a laminate,
substrate/adhesive layer/sealant layer,
substrate/printing layer/adhesive layer/sealant layer,
Substrate/transparent gas barrier layer/printing layer/adhesive layer/sealant layer, or substrate/transparent gas barrier layer/adhesive layer/sealant layer,
The base material contains 51% by mass or more of polybutylene terephthalate,
The laminate has an impact strength of 800 kJ/m or more.

In the laminate according to the present invention, the substrate may contain 60% by mass or more of polybutylene terephthalate.

In the laminate according to the present invention, the puncture strength of the laminate is preferably 11 N or more.

In the laminate according to the present invention, the sealant layer may contain 90% by mass or more of polypropylene. Further, the sealant layer may contain a propylene/ethylene block copolymer.

In the laminate according to the present invention, the sealant layer may contain polyethylene having a melting point of 100° C. or higher.

In the laminate according to the present invention, the adhesive layer is a cured product of a polyol and an aliphatic isocyanate compound, and the molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxy groups of the polyol is 3.5 or more. may

In the laminate according to the present invention, the substrate may have a multilayer structure containing 10 or more layers. Alternatively, the substrate may consist of a single layer structure having an IV value of 1.10 dl/g or more and 1.35 dl/g or less.

In the laminate according to the present invention, the sealant layer may contain a thermoplastic elastomer.

The present invention is a bag comprising:
a laminate comprising an outer surface and an inner surface;
and a sealing portion that joins the inner surfaces of the laminate,
The laminate comprises, in order from the outer surface side to the inner surface side, a substrate/adhesive layer/sealant layer,
substrate/printing layer/adhesive layer/sealant layer,
Substrate/transparent gas barrier layer/printing layer/adhesive layer/sealant layer, or substrate/transparent gas barrier layer/adhesive layer/sealant layer,
The base material contains 51% by mass or more of polybutylene terephthalate,
In the bag, the laminate has an impact strength of 800 kJ/m or more.

ADVANTAGE OF THE INVENTION According to this invention, the laminated body which is the laminated|stacked body which laminated|stacked two films, Comprising: The laminated body which has the outstanding impact resistance can be provided.

It is a front view showing a bag in an embodiment of the invention. FIG. 2 is an exploded view showing a film that constitutes the bag shown in FIG. 1; FIG. 2 is a cross-sectional view showing an example of the layer structure of a laminate that constitutes a bag; FIG. 4 is a cross-sectional view showing an example of a layer structure of a first film of a laminate; FIG. 10 is a cross-sectional view showing another example of the layer structure of the laminate that constitutes the bag; FIG. 4 is a front view showing a bag with its top sealed; It is a front view which shows the bag in the example of a changed completely type of embodiment of this invention. FIG. 2 is a plan view showing a test piece for evaluating impact strength; FIG. 9 is a cross-sectional view of the test piece shown in FIG. 8; It is a figure which shows an example of the measuring method of impact strength. It is a figure which shows an example of the measuring method of a puncture strength. FIG. 5 is a diagram showing evaluation results of Examples 1 to 5 and Comparative Examples 1 to 3;

An embodiment of the present invention will be described with reference to FIGS. 1 to 6. FIG. In addition, in the drawings attached to this specification, for convenience of illustration and easy understanding, the scale, the ratio of length and width, etc. are appropriately changed and exaggerated from those of the real thing.

In addition, the terms such as "parallel", "perpendicular", "same" and the like, length and angle values, etc. that specify shapes and geometric conditions and their degrees used in this specification are strictly It shall be interpreted to include the extent to which similar functions can be expected without being bound by the meaning.

FIG. 1 is a front view showing a bag 10 according to this embodiment. 2 is an exploded view showing a film that constitutes the bag shown in FIG. 1. As shown in FIG. The bag 10 includes a containing portion 17 containing contents. Note that FIG. 1 shows the bag 10 in a state in which no contents are contained therein. The bag 10 according to this embodiment is configured to be able to undergo retort treatment. The configuration of the bag 10 will be described below.

Bag In the present embodiment, the bag 10 is a gusseted bag that can stand on its own. The bag 10 includes an upper portion 11, a lower portion 12 and side portions 13 and has a generally rectangular profile in front view. The terms "upper", "lower" and "side", as well as terms such as "upper" and "lower" are based on the bag 10 standing on its own with the gussets down. It is merely a relative representation of the positions and directions of 10 and its components. The posture of the bag 10 during transportation and use is not limited by the names and terms used in this specification.

As shown in FIGS. 1 and 2, the bag 10 includes a surface film 14 that forms the front surface, a back film 15 that forms the back surface, and a lower film 16 that forms the lower portion 12 . The lower film 16 is arranged between the surface film 14 and the back film 15 while being folded back at the folding portion 16f.

The terms "surface film", "back surface film", and "lower film" described above merely refer to sections of each film according to their positional relationship, and the method of providing the films when manufacturing the bag 10 is as follows: Do not be limited by the above terms. For example, the bag 10 may be manufactured using one film in which the surface film 14, the back film 15, and the bottom film 16 are continuously provided, or one film in which the surface film 14 and the bottom film 16 are continuously provided. It may be manufactured using a total of two films, a film and a backing film 15, or a total of three films, one fronting film 14, one backing film 15, and one bottom film 16. may be manufactured using

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

As shown in FIG. 1, the seal has an outer edge seal extending along the outer edge of bag 10 . The outer edge seal portion includes a lower seal portion 12 a extending over the lower portion 12 and a pair of side seal portions 13 a extending along the pair of side portions 13 . As shown in FIG. 1, in the bag 10 before it is filled with the content (the state where the content is not filled), the upper portion 11 of the bag 10 is an opening 11b. After the contents are contained in the bag 10, the inner surface of the surface film 14 and the inner surface of the back film 15 are joined at the upper portion 11 to form an upper sealing portion and seal the bag 10. As shown in FIG.

The side seal portion 13a and the upper seal portion, which will be described later, are seal portions formed by joining the inner surface of the surface film 14 and the inner surface of the back film 15 together. On the other hand, the lower seal portion 12a is formed by joining the inner surface of the front film 14 and the inner surface of the lower film 16 together, and by joining the inner surface of the back film 15 and the inner surface of the lower film 16 together. including a configured seal.

As long as the opposing films can be joined together to seal the bag 10, the method for forming the seal portion is not particularly limited. For example, the inner surface of the film may be melted by heating and the inner surfaces may be welded to each other, that is, by heat sealing to form the sealed portion. Alternatively, the sealing portion may be formed by bonding the inner surfaces of the films facing each other using an adhesive or the like.

Easy Open Means The front film 14 and the back film 15 may be provided with an easy open means 25 for tearing the front film 14 and the back film 15 to open the bag 10 . For example, as shown in FIG. 1, the easy-opening means 25 may include a notch 26 formed in the side seal portion 13a of the bag 10 to serve as a starting point for tearing. In addition, a half-cut line formed by laser processing, a cutter, or the like may be provided as the easy-to-open means 25 on the portion that becomes the path for tearing the bag 10 .

Moreover, although not shown, the easy-opening means 25 may include cuts or scars formed in the areas of the surface film 14 and the back film 15 where the seal portions are formed. The scar group may include, for example, a plurality of through holes formed through the front film 14 and/or the back film 15 . Alternatively, the scars may include a plurality of holes formed in the outer surface of the top film 14 and/or the back film 15 so as not to penetrate the top film 14 and/or the back film 15 .

Layer Structure of Front Film and Back Film Next, the layer structure of the front film 14 and the back film 15 will be described. FIG. 3 is a cross-sectional view showing a laminate 30 forming the surface film 14 and the back film 15. As shown in FIG.

As shown in FIG. 3 , the laminate 30 includes a first film 40 and a second film 50 laminated on the first film 40 with an adhesive layer 60 interposed therebetween. The first film 40 is positioned on the outer surface 30y side, and the second film 50 is positioned on the inner surface 30x side opposite to the outer surface 30y. The inner surface 30x is a surface of the bag 10 configured by the laminate 30 facing the accommodating portion 17 side, and the outer surface 30y is a surface located on the opposite side of the inner surface 30x.

The first film 40 includes at least a substrate 41 . Also, the first film 40 may further include a printed layer 42 provided on the inner surface 30x side of the substrate 41 . The second film 50 also includes a sealant layer 51 . Therefore, it can be said that the laminate 30 according to the present embodiment comprises a substrate/printing layer/adhesive layer/sealant layer in order from the outer surface side to the inner surface side. Note that "/" represents a boundary between layers.

Each of the first film 40, the second film 50 and the adhesive layer 60 will be described in detail below.

(First film)
The first film 40 includes at least a base material 41 forming the outer surface 30y of the laminate 30 . As shown in FIG. 3 , the first film 40 may further include a printed layer 42 provided on the inner surface 30x side of the substrate 41 .

〔Base material〕
The base material 41 contains polybutylene terephthalate (hereinafter also referred to as PBT) as a main component. For example, the base material 41 contains 51% by mass or more of PBT. Advantages of the base material 41 containing PBT will be described below.

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

Moreover, PBT is excellent in heat resistance. Therefore, deformation of the base material 41 and reduction in strength of the base material 41 can be suppressed when the bag 10 is subjected to boiling treatment or retort treatment. The retort treatment is a treatment in which the contents are filled into the bag 10, the bag 10 is sealed, and then the bag 10 is heated 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 contents into the bag 10, sealing the bag 10, and then boiling the bag 10 in hot water under atmospheric pressure. The boiling treatment temperature is, for example, 90° C. or higher and 100° C. or lower.

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

In addition, PBT has the characteristic of being less likely to absorb moisture than nylon. Therefore, even when the base material 41 containing PBT is arranged on the outer surface 30y of the laminate 30, it is possible to prevent the base material 41 from absorbing moisture and lowering the laminate strength of the laminate 30. can be done.

The configuration of the base material 41 containing PBT will be described in detail below. As the configuration of the base material 41 containing PBT in the present embodiment, either the following first configuration or second configuration may be employed.

[First configuration of base material]
The content of PBT in the substrate 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 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.

PBT used as a main component preferably contains 90 mol% or more, more preferably 95 mol% or more, still more preferably 98 mol% or more, and most preferably 100% terephthalic acid as a dicarboxylic acid component. in mol %. 1,4-Butanediol is preferably 90 mol % or more, more preferably 95 mol % or more, still more preferably 97 mol % or more, and most preferably 1,4-butanediol as a glycol component during polymerization. It does not contain anything other than by-products produced by the ether bond of butanediol.

The base material 41 may contain a polyester resin other than PBT. This makes it possible to adjust the film formability and the mechanical properties of the base material 41 when the film base material 41 is biaxially stretched, for example.
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, naphthalenedicarboxylic acid, and biphenyldicarboxylic acid. , PBT resins 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 obtained by copolymerizing diol components such as -pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, and polycarbonate diol.

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

The base material 41 may contain, as an additive, a polyester-based or polyamide-based elastomer obtained by copolymerizing at least one of a flexible polyether component, polycarbonate component, and polyester component. This can improve pinhole resistance when bent. The additive amount is, for example, 20% by mass. If the additive amount exceeds 20% by mass, the effect of the additive may be saturated, or the transparency of the base material 41 may be reduced.

An example of a method for producing the film-shaped base material 41 according to the first configuration will be described. Here, a method of producing the film-like base material 41 by a casting method will be described. More specifically, a method of casting multiple layers of resin having the same composition at the time of casting will be described.

Since PBT has a high crystallization speed, crystallization proceeds even during casting. At this time, if a single layer is cast without multilayering, there is no barrier that can suppress the growth of crystals, so the crystals grow to a large size, resulting in an unstretched raw roll. yield stress is higher. For this reason, it becomes easy to break when biaxially stretching an unstretched raw fabric. Moreover, 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 multi-layered 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 base material 41 is produced by casting a multilayered resin, as shown in FIG. 4, the base material 41 of the first film 40 is composed of a multi-layer structure including a plurality of layers 41a. Each of the multiple layers 41a contains PBT as a main component. For example, each of the layers 41a preferably contains 51% by mass or more of PBT, more preferably 60% by mass or more of PBT. In the plurality of layers 41a, the n+1th layer 41a is directly laminated on the nth layer 41a. That is, no adhesive layer or bonding layer is interposed between the 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 resin compositions are the same, interfaces between layers exist, and the interfaces accelerate crystallization. On the other hand, the growth of large crystals beyond the thickness of the layer is suppressed. For this reason, it is considered 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 multi-manifold, etc.) can be used. For example, a method of laminating thermoplastic resins fed from different flow paths using two or more extruders into multiple layers using a feed block, a static mixer, a multi-manifold die, or the like can be used. In the case of multilayering resins of the same composition, it is also possible to use only one extruder and introduce the multilayering device described above into the melt line from the extruder to the die.

The base material 41 is composed of a multi-layer structure including at least 10 layers or more, 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 the spherulites in the unstretched original PBT can be reduced, and the subsequent biaxial stretching can be stably carried out. Moreover, the yield stress of PBT in the state of a biaxially stretched film can be reduced. Preferably, the diameter of the spherulites in the unstretched raw PBT is 500 nm or less.

When a biaxially stretched film is produced by biaxially stretching an unstretched raw PBT film, the stretching temperature (hereinafter also referred to as MD stretching temperature) in the longitudinal stretching direction (hereinafter, MD) is preferably 40 ° C. or higher. and more preferably 45° C. or higher. By setting the MD stretching temperature to 40° C. or higher, it is possible to suppress the occurrence of breakage of the film. Also, 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 the orientation of the biaxially stretched film does not occur.

The draw ratio in MD (hereinafter also referred to as MD draw 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 draw ratio is, for example, 5 times or less.

The stretching temperature (hereinafter also referred to as TD stretching temperature) in the lateral 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 suppress the occurrence of breakage of the film. Moreover, the TD stretching temperature is preferably 100° C. or lower. By setting the TD stretching temperature to 100° C. or lower, it is possible to suppress the phenomenon that the biaxially stretched film is not oriented.

The draw ratio in TD (hereinafter also referred to as TD draw 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 draw 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 film of PBT. Also, the TD relaxation rate is preferably 10% or less. As a result, it is possible to suppress the occurrence of unevenness in thickness due to sagging or the like in the biaxially stretched PBT film.

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

[Second configuration of base material]
The base material 41 according to the second configuration is composed of a single-layer film containing polyester having butylene terephthalate as a main repeating unit. For example, the base material 41 is mainly composed of 1,4-butanediol as a glycol component or an ester-forming derivative thereof, and terephthalic acid as a dibasic acid component or an ester-forming derivative thereof. including homo- or copolymer-type polyesters obtained by The content of PBT in the substrate 41 according to the second configuration is preferably 51% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, further preferably 80% by mass or more, and most preferably. is 90% by mass or more. Moreover, it is preferable that the base material 41 according to the second configuration is composed only of polybutylene terephthalate and an additive.

In order to impart mechanical strength to the base material 41, PBT having 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 is preferred. 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 that makes up substrate 41 . IV values can be calculated based on JIS K 7367-5:2000.

The base material 41 according to the second configuration may contain a polyester resin other than PBT, such as PET, within a range of 30% by mass or less. By including PET in addition to PBT in the base material 41, crystallization of PBT can be suppressed, and stretchability of the PBT film can be improved. As the PET mixed with the PBT of the base material 41, a polyester having ethylene terephthalate as a main repeating unit can be used. For example, a homotype containing ethylene glycol as a glycol component and terephthalic acid as a dibasic acid component as main components can be preferably used. In order to impart good mechanical strength properties, PET preferably has 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 preferable.
By setting the amount of PET to be 30% by mass or less, it is possible to prevent the stiffness of the unstretched raw fabric and stretched film from becoming too high. As a result, it is possible to prevent the stretched film from becoming brittle and the pressure resistance, impact strength, puncture strength, etc. of the stretched film from deteriorating. In addition, it is possible to suppress the occurrence of stretching failure when stretching an unstretched raw material.

The base material 41 optionally contains a lubricant, an antiblocking agent, an inorganic extender, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a plasticizer, a coloring agent, a crystallization inhibitor, and a crystallization accelerator. It may contain additives such as In addition, the polyester resin pellets used as the raw material of the base material 41 have a moisture content of 0.05% by weight or less, preferably 0.01% by weight or less before being heated and melted, in order to avoid a decrease in viscosity due to hydrolysis during heating and melting. It is preferable to use it after pre-drying sufficiently so that it becomes

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

In order to stably produce a film of the base material 41 having the structure described above, it is important to suppress the growth of crystals in the state of the unstretched original sheet. Specifically, when the 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 original fabric cooling rate is an important factor. The raw fabric cooling rate is, for example, 200° C./second or higher, preferably 250° C./second or higher, and particularly preferably 350° C./second or higher. Since the unstretched raw material film-formed at a high cooling rate maintains a low crystallinity, the stability of bubbles during stretching is improved. Furthermore, film formation at high speed becomes possible, so the productivity of the film is also improved. If the cooling rate is less than 200° C./second, it is conceivable that the crystallinity of the obtained unstretched raw material is high and the stretchability is lowered. In extreme cases, the stretching bubble may burst and the stretching may not continue.

The unstretched raw sheet containing PBT as a main component is preferably conveyed to a space for biaxial stretching while maintaining the ambient temperature at 25°C or lower, preferably 20°C or lower. As a result, even when the residence time is long, the crystallinity of the unstretched raw sheet immediately after film formation can be maintained.

A biaxial stretching method for stretching an unstretched raw fabric to obtain a stretched film is not particularly limited. For example, the longitudinal direction and the transverse direction may be stretched simultaneously, or the longitudinal direction and the transverse direction may be successively stretched by a tubular method or a tenter method. Among these methods, the tubular method is particularly preferably employed because it is possible to obtain a stretched film having a good balance of physical properties in the circumferential direction.

In the tubular method, an unstretched raw material introduced into a stretching space is passed between a pair of low-speed nip rolls and then heated by a stretching heater while air is forced therein. After the stretching is finished, air is blown to the stretched film by a cooling shoulder air ring. The draw ratio is preferably 2.7 times or more and 4.5 times or less in MD and TD, respectively, in consideration of the stretching stability, strength properties, transparency, and thickness uniformity of the stretched film. By setting the stretching ratio to 2.7 times or more, it is possible to sufficiently secure the tensile modulus and impact strength of the stretched film. In addition, by setting the draw ratio to 4.5 times or less, it is possible to suppress the occurrence of excessive strain of the molecular chain due to stretching, and it is possible to suppress the occurrence of breakage and puncture during the stretching process, so the stretched film can be stabilized. can be made.

The stretching temperature is preferably 40° C. or higher and 80° C. or lower, and particularly preferably 45° C. or higher and 65° C. or lower. Since the unstretched raw fabric produced at the above-described high cooling rate has low crystallinity, the unstretched raw fabric can be stably stretched even when the stretching temperature is relatively low. Further, by setting the stretching temperature to 80° C. or lower, it is possible to suppress the shaking of the stretching bubble and obtain a stretched film with good thickness accuracy. In addition, by setting the stretching temperature to 40° C. or higher, it is possible to suppress the occurrence of excessive stretching orientation crystallization due to low-temperature stretching, thereby preventing whitening of the film.

The substrate 41 manufactured as described above is composed of, for example, a single layer containing polyester having butylene terephthalate as a main repeating unit. According to the production method described above, since the unstretched raw fabric is formed into a film at a high cooling rate, even when the unstretched raw fabric is composed of a single layer, it is possible to maintain a low crystalline state, Therefore, the unstretched raw fabric can be stably stretched.

[Print layer]
The printed layer 42 is a layer printed on the base material 41 in order to indicate product information on the bag 10 and to give it an aesthetic appearance. The print layer 42 expresses characters, numbers, symbols, graphics, patterns, and the like. As a material forming the printing layer 42, ink for gravure printing or ink for flexographic printing can be used.

The ink forming the printing layer 42 contains a binder and a pigment. The binder includes, for example, polyurethane or the like, similar to the adhesive layer 60 described below. Polyurethane is a cured product produced by reacting a polyol as a main agent with an isocyanate compound as a curing agent. Details of the polyol and isocyanate compounds are described in the adhesive layer 60 paragraph.

The pigments of the printed layer 42 are colored powders and are present in the binder at a predetermined distribution density. The color exhibited by the pigment is not particularly limited, and various pigments such as red, blue, green, white, and black can be used. For example, the average particle size of the pigment may be 0.1 μm or more and 1 μm or less, or 0.5 μm or more and 1 μm or less. It should be noted that white pigments generally have larger dimensions than pigments of other colors. For example, the white pigment has an average particle size of 0.5 μm or more and 1 μm or less. The average particle size of pigments can be measured by a dynamic light scattering method.

The print layer 42 may consist of a single layer or may include multiple layers. For example, the printed layer 42 may include a first layer containing a pigment exhibiting a first color and a second layer containing a pigment exhibiting a second color different from the first color. . The thickness of one layer of the printed layer 42 is, for example, 0.5 μm or more and 3 μm or less.

[Gas barrier layer]
FIG. 5 is a cross-sectional view showing another example of the layer structure of the laminate 30. As shown in FIG. As shown in FIG. 5, the first film 40 of the laminate 30 may further include a transparent gas barrier layer 43 located on the inner surface 30x side of the substrate 41 and having transparency. In this case, the printed layer 42 is positioned on the inner surface 30 x side of the transparent gas barrier layer 43 . It can be said that the laminate 30 in the example shown in FIG. 5 comprises a substrate/transparent gas barrier layer/printing layer/adhesive layer/sealant layer in order from the outer surface side to the inner surface side.

The transparent gas barrier layer 43 will be described below. The transparent gas barrier layer 43 is formed on the inner surface 30x side of the base material 41 and includes at least a transparent deposition layer 43a made of a transparent inorganic material. The transparent gas barrier layer 43 may further include a transparent gas barrier coating film 43b formed on the inner surface 30x side of the transparent deposition layer 43a. In this case, it can be said that the laminate 30 is provided with substrate/transparent deposition layer/transparent gas barrier coating film/printing layer/adhesive layer/sealant layer in order from the outer surface side to the inner surface side.

The transparent deposited layer 43a functions as a layer having a gas barrier function to block permeation of oxygen gas and water vapor. Two or more layers of the transparent deposition layer 43a may be provided. When there are two or more transparent deposition layers 43a, they may have the same composition or may have different compositions. Examples of the method for forming the transparent deposition layer 43a include physical vapor deposition methods (physical vapor deposition method, PVD method) such as vacuum deposition method, sputtering method, and ion plating method, plasma chemical vapor deposition method, Chemical vapor deposition methods (Chemical Vapor Deposition method, CVD method) such as thermal chemical vapor deposition method and photochemical vapor deposition method can be used. Specifically, a vapor deposition layer can be formed on a film forming roller using a roller type vapor deposition film forming apparatus.

The transparent deposition layer 43a is made of a transparent inorganic substance such as aluminum oxide (aluminum oxide) or silicon oxide. It is preferable to use an amorphous thin film of aluminum oxide as the transparent deposition layer 43a. Specifically, the transparent deposited layer 43a is an amorphous thin film of aluminum oxide represented by the formula AlO _x (wherein X represents a number in the range of 0.5 to 1.5). . For the transparent deposition layer 43a, an amorphous aluminum oxide thin film can be used in which the value of X decreases in the depth direction from the film surface toward the inner surface. The amorphous thin film of aluminum oxide is represented by the formula AlO _x (wherein X represents a number in the range of 0.5 to 1.5), and the depth direction from the thin film surface to the inner surface is It is preferred that the value of X increases in the direction. As for the value of X in the above formula, basically X=0.5 or more can be used. It is preferable to use one with X=1.0 or more because it is inferior in the properties. Moreover, since the one with X=1.5 is in a state in which Al is completely oxidized, the upper limit of X=1.5 can be used. In addition, when the value of X in the above formula is 0, it is a complete inorganic simple substance (pure substance) and is not transparent.

The rate of decrease in the value of X can be determined, for example, by using a surface analysis device such as Xray Photoelectron Spectroscopy (XPS) or Secondary Ion Mass Spectroscopy (SIMS) in the depth direction. This can be confirmed by performing an elemental analysis of the transparent deposition layer 43a using a method of performing analysis such as ion etching.

The transparent deposition layer 43a 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 deposition layer 43a is 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 may indicate the presence of bonding, and may have transparency and gas barrier properties to prevent 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 deposition layer 43a and the substrate 41 . For example, when the transparent deposition layer 43a contains aluminum oxide, covalent bonds between aluminum atoms and carbon atoms can be formed at the interface between the substrate 41 and the transparent deposition layer 43a. A covalent bond can be detected by measurement by X-ray photoelectron spectroscopy (hereinafter abbreviated as “XPS measurement”).

In the transparent deposition layer 43a, the existence ratio of covalent bonds between aluminum atoms and carbon atoms is the total bond including carbon atoms observed when the interface between the transparent deposition layer 43a and the substrate 41 is measured by XPS measurement. of 0.3% or more and 30% or less. As a result, the adhesiveness between the transparent deposited layer 43a and the substrate 41 is strengthened, the transparency is excellent, and a well-balanced performance as a gas barrier deposited film can be obtained.

If the abundance ratio of covalent bonds between aluminum atoms and carbon atoms is less than 0.3%, the adhesion of the transparent deposited layer 43a is insufficiently improved, making it difficult to stably maintain barrier properties.

Furthermore, the AL (aluminum)/O (oxygen) ratio of the transparent vapor deposition layer 43a containing aluminum oxide as a main component is the transparent vapor deposition on the side opposite to the substrate 41 from the interface between the substrate 41 and the transparent vapor deposition layer 43a. It is preferably 1.0 or less within a range up to 3 nm toward the surface of layer 43a.
If the AL/O ratio exceeds 1.0 in the range from the interface between the transparent vapor deposition layer 43a and the base material 41 toward the surface of the transparent vapor deposition layer 43a opposite to the base material 41, the base material 41 and The adhesion with the transparent vapor deposition layer 43a becomes insufficient, and the proportion of aluminum increases, reducing the transparency of the transparent vapor deposition layer 43a.

The thickness of the transparent deposition layer 43a is, for example, 30 Å or more and 150 Å or less. If it is less than 30 Å, the gas barrier property may be insufficient even when the transparent gas barrier coating film 43b is used together. 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 deposition layer 43a exceeds 150 Å, the flexibility of the laminate 30 decreases, and when the laminate 30 is used for the bag 10, a part of the transparent vapor deposition layer 43a cracks or cracks. It is thought that pinholes are generated and the gas barrier property is lowered. The thickness of the transparent deposited layer 43a 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 deposited layer 43a can be measured by a fundamental parameter method using, for example, a fluorescent X-ray analyzer (trade name: RIX2000, manufactured by Rigaku Corporation). As a means for changing the thickness of the transparent vapor deposition layer 43a, a method of changing the deposition speed of the transparent vapor deposition layer 43a, a method of changing the vapor deposition speed, or the like can be used.

When forming the transparent deposition layer 43a on the inner surface 30x side of the base material 41, the surface of the inner surface 30x side of the base material 41 may be subjected to pretreatment such as corona discharge treatment, flame treatment, or plasma treatment in advance. good. In particular, when forming a covalent bond between a metal atom and a carbon atom at the interface between the transparent deposition layer 43a and the base material 41, the surface of the base material 41 on which the transparent deposition layer 43a is to be formed is pretreated. is preferred. When the pretreatment is plasma treatment, the pretreatment apparatus supplies plasma to the surface of the base material 41 under a reduced pressure environment of 0.1 Pa or more and 100 Pa or less. Plasma is generated by using an inert gas such as argon alone or a mixed gas of oxygen, nitrogen, carbon dioxide, and one or more of these gases as a plasma raw material gas, and the plasma raw material gas is excited by a potential difference due to a high frequency voltage or the like. can be generated by

The pretreatment can confine the plasma near the surface of the substrate 41 . As a result, the shape of the surface of the base material 41, the chemical bonding state, and the functional groups can be changed, and the chemical properties of the surface of the base material 41 can be changed. This makes it possible to improve the adhesion between the base material 41 and the transparent deposition layer 43a.

The transparent gas barrier coating film 43b is a layer that functions as a layer that suppresses permeation of oxygen gas and water vapor. The transparent gas barrier coating film 43b has the 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 at least one or more alkoxides represented by the above polyvinyl alcohol- A transparent gas barrier composition that contains a sol-based resin and/or an ethylene-vinyl alcohol copolymer, and is polycondensed by the sol-gel method in the presence of a sol-gel catalyst, acid, water, and an organic solvent. can get.

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

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

Further, in the alkoxide represented by the general formula R ¹ _n M(OR ² ) _m , specific examples of the organic group represented by R ¹ include a methyl group, an ethyl group, an n-propyl group, i -propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-hexyl group, n-octyl group, and the like. Further, in the alkoxide represented by the general formula R ¹ _n M(OR ² ) _m , specific examples of the organic group represented by R ² include a methyl group, an ethyl group, an n-propyl group, i -propyl group, n-butyl group, sec-butyl group, and the like. These alkyl groups may be the same or different in the same molecule.

For example, a silane coupling agent or the like may be added when preparing the transparent gas barrier composition. Known organic reactive group-containing organoalkoxysilanes can be used as the silane coupling agent. In particular, organoalkoxysilanes having an epoxy group are preferably used, and specific examples include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, or β-(3, 4-epoxycyclohexyl)ethyltrimethoxysilane and the like can be used. The above silane coupling agents may be used singly or in combination of two or more.

(Second film)
The second film 50 includes at least a sealant layer 51 forming the inner surface 30x of the laminate 30. As shown in FIG. As a material for forming the sealant layer 51, one or more resins selected from polyethylene such as low-density polyethylene, linear low-density polyethylene, and polypropylene can be used. The sealant layer 51 may be a single layer or multiple layers. Moreover, the sealant layer 51 is preferably made of an unstretched film. The term "unstretched" is a concept including not only films that are not stretched at all but also films that are slightly stretched due to the tension applied during film formation.

As described above, the bag 10 composed of the laminate 30 is subjected to sterilization treatment such as boiling treatment and retort treatment at a high temperature. Therefore, the sealant layer 51 used has heat resistance to withstand these high-temperature treatments.

The melting point of the material forming the sealant layer 51 is preferably 150° C. or higher, more preferably 160° C. or higher. By increasing the melting point of the sealant layer 51, the bag 10 can be retorted at a high temperature, thereby shortening the time required for the retort treatment. The melting point of the material forming the sealant layer 51 is lower than the melting point of the resin forming the base material 41 .

From the viewpoint of retort treatment, a material containing propylene as a main component can be used as the material forming the sealant layer 51 . Here, the material "mainly composed of propylene" means a material having a propylene content of 90% by mass or more. Specific examples of materials containing propylene as a main component include polypropylenes such as propylene/ethylene block copolymers, propylene/ethylene random copolymers, and homopolypropylenes, and mixtures of polypropylene and polyethylene. can be done. Here, "propylene/ethylene block copolymer" means a material having a structural formula shown in formula (I) below. Further, the “propylene/ethylene random copolymer” means a material having the structural formula shown in formula (II) below. Further, "homopolypropylene" means a material having a structural formula shown in formula (III) below.

When a mixture of polypropylene and polyethylene is used as the propylene-based material, 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 region in which polypropylene is continuous.

From the viewpoint of boiling treatment, examples of the material forming the sealant layer 51 include polyethylene, polypropylene, or a combination thereof. Examples of polyethylene include medium density polyethylene, linear low density polyethylene, or combinations thereof. For example, it is also possible to use the materials listed as the materials constituting the sealant layer from the viewpoint of the retort treatment described above. The material constituting the sealant layer has a melting point of, for example, 100° C. or higher, more preferably 105° C. or higher, and even 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 polyethylene has a density of 0.920 g/cm ³ or higher. Specific examples of the sealant film for constructing 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 Unitech. Specific examples of the sealant film for constructing the sealant layer having a melting point of 105° C. or higher include NB-1 manufactured by Tamapoly. Specific examples of the sealant film for constructing the sealant layer having a melting point of 110° C. or higher include LS760C manufactured by Idemitsu Unitech and TUX-HZ manufactured by Mitsui Chemicals Tohcello.

Preferably, sealant layer 51 comprises a propylene-ethylene block copolymer. For example, the second film 50 including the sealant layer 51 is an unstretched film whose main component is a propylene/ethylene block copolymer. By using the propylene/ethylene block copolymer, the impact resistance of the laminate 30 including the second film 50 can be enhanced, thereby suppressing the bag 10 from breaking due to impact when dropped. can do. In addition, the stab resistance of the laminate 30 can be enhanced.

Moreover, the sealant layer 51 may further contain a thermoplastic elastomer. By using a thermoplastic elastomer, the impact resistance and puncture resistance of the second film 50 can be further enhanced.

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. . The thermoplastic elastomer may also be an ethylene/α-olefin elastomer. Ethylene/α-olefin elastomers are low-crystalline or amorphous copolymer elastomers, and are random copolymers of 50 to 90% by mass of ethylene as a main component and α-olefin as a copolymerization monomer. be.

The content of the propylene/ethylene block copolymer in the sealant layer 51 is, for example, 80% by mass or more, preferably 90% by mass or more.

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

The thickness of the sealant layer 51 is preferably 30 μm or more, more preferably 40 μm or more. Also, the thickness of the sealant layer 51 is preferably 100 μm or less, more preferably 80 μm or less.

(adhesive layer)
The adhesive layer 60 contains an adhesive for bonding the first film 40 and the second film 50 together. The adhesive constituting the adhesive layer 60 is produced from an adhesive composition prepared by mixing a first composition containing a main agent and a solvent and a second composition containing a curing agent and a solvent. Specifically, the adhesive includes a cured product produced by reacting the main agent and solvent in the adhesive composition.

Examples of adhesives include ether-based two-component reactive adhesives and ester-based two-component reactive adhesives. Examples of the ether-based two-liquid reactive adhesive include polyether polyurethane. A polyether polyurethane is a cured product produced by reacting a polyether polyol as a main agent with an isocyanate compound as a curing agent. Examples of ester-based two-liquid reactive adhesives include polyester polyurethane and polyester. A polyester polyurethane is a cured product produced by reacting a polyester polyol as a main agent with an isocyanate compound as a curing agent.

As isocyanate compounds that react with polyols such as polyether polyols and polyester polyols to form cured products, there are aromatic isocyanate compounds and aliphatic isocyanate compounds. Among them, the aromatic isocyanate compound elutes components that cannot be used for food under a high-temperature environment such as during heat sterilization (retort treatment). By the way, the adhesive layer 60 is in contact with the second film 50 forming the inner surface 30x of the laminate 30, as shown in FIGS. Therefore, when the adhesive layer 60 contains an aromatic isocyanate compound, a component eluted from the aromatic isocyanate compound may adhere to the contents of the bag 10 configured by the laminate 30.

In consideration of such problems, as the adhesive constituting the adhesive layer 60, a cured product produced by reacting a polyol as a main agent and an aliphatic isocyanate compound as a curing agent is used. As a result, it is possible to prevent components that cannot be used for food from adhering to the contents due to the adhesive layer 60 . Aliphatic isocyanates include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and the like.

As shown in Examples described later, the impact resistance can be enhanced by increasing the molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxyl groups of the polyol. For example, the molar ratio of the curing agent (aliphatic isocyanate compound) to the hydroxyl group of the main agent (polyol) is conventionally about 3. In the present embodiment, the molar ratio of the isocyanate group of the aliphatic isocyanate compound to the hydroxy group of the polyol is preferably 3.5 or more, more preferably 4 or more, and 4.5 or more. is more preferred. More preferably, the molar ratio of isocyanate groups of the aliphatic isocyanate compound to hydroxy groups of the polyol is greater than five.

On the other hand, the aliphatic isocyanate compound is expensive, and increasing the amount of the aliphatic isocyanate compound is not preferable in terms of production cost. Also, the higher the molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxy groups of the polyol, the higher the temperature or the longer the time required to cure the adhesive composition. Considering these points, the molar ratio of aliphatic isocyanate groups to hydroxy groups is preferably 7 or less, more preferably 6 or less.

The adhesive layer 60 is formed by applying an adhesive composition to the first film 40 or the second film 50, then drying the adhesive composition, and reacting the main agent and solvent in the adhesive composition. It is formed by curing the adhesive composition. In the present embodiment, the weight per unit area of the adhesive composition after drying is preferably 2 g/m ² or more and 5 g/m ² or less, and preferably 3 g/m ² or more and 4 g/m ² or more. More preferably: The thickness of the adhesive layer 60 is preferably 2 μm or more and 5 μm or less, more preferably 3 μm or more and 4 μm or less.

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

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

Method for Manufacturing 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, the film-like substrate 41 is produced by extruding the resin material by a melt extrusion method such as a casting method or a tubular method. Subsequently, an inorganic material such as aluminum oxide may be vapor-deposited on the film-like substrate 41 to form the transparent vapor-deposited layer 43a. Subsequently, a transparent gas barrier composition may be applied onto the transparent deposition layer 43a to form a transparent gas barrier coating film 43b. After that, the printed layer 42 is formed on the substrate 41 or the transparent gas barrier coating film 43b. Thus, the first film 40 comprising the base material 41 and the printed layer 42, or the base material 41, the transparent gas barrier layer 43 including the transparent deposition layer 43a and the transparent gas barrier coating film 43b, and the printed layer 42 It is possible to obtain the first film 40 comprising

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

First, a first composition containing a main agent and a solvent is mixed with a second composition containing a curing agent and a solvent to prepare an adhesive composition. An adhesive composition is then applied to the first film 40 or the second film 50 . For example, it is applied onto the printed layer 42 of the first film 40 . Subsequently, the applied adhesive composition is dried to volatilize the solvent. Thereafter, the first film 40 and the second film 50 are laminated via the dried adhesive composition. Subsequently, the laminate is heated, for example, in an environment of 20° C. or higher for 24 hours or longer. Thereby, the adhesive composition is cured to obtain an adhesive containing a cured product of the polyol and the aliphatic isocyanate compound. Thus, the laminate 30 including the first film 40 and the second film 50 can be obtained.

Bag Manufacturing Method A surface film 14 and a back film 15 comprising the laminate 30 described above are prepared. In addition, the folded lower film 16 is inserted between the surface film 14 and the back film 15 . Subsequently, the inner surfaces of the films are heat-sealed to form seal portions such as the lower seal portion 12a and the side seal portions 13a. Also, the films bonded together by heat sealing are cut into a suitable shape to obtain the bag 10 shown in FIG. Subsequently, the content 18 is filled into the bag 10 through the opening 11b of the upper portion 11. As shown in FIG. Contents 18 are, for example, cooked foods containing water, such as curry, stew, and soup. After that, the upper portion 11 is heat-sealed to form an upper seal portion 11a. In this way, as shown in FIG. 6, the sealed bag 10 containing the contents 18 can be obtained.

(Effect of this embodiment)
According to the present embodiment, since the laminate 30 constituting the surface film 14 and the back film 15 includes the base material 41 containing PBT as a main component, the following effects can be obtained.
First, PBT is excellent in printability. Therefore, as in the case of polyethylene terephthalate (hereinafter also referred to as PET), the printed layer 42 can be provided on the base material 41 containing PBT.
Moreover, PBT is excellent in heat resistance. Therefore, deformation of the base material 41 and reduction in strength of the base material 41 can be suppressed when the bag 10 is subjected to boiling treatment or retort treatment.
PBT also has high strength. For this reason, the bag 10 can be provided with piercing resistance as in the case where the laminate constituting the bag 10 contains nylon. The puncture strength of the laminate constituting the bag 10 is preferably 11 N or more, more preferably 13 N or more, and even more preferably 15 N or more. A method for measuring the puncture strength will be described in Example 1 below.
In addition, PBT has the characteristic of being less likely to absorb moisture than nylon. Therefore, even when the base material 41 containing PBT is arranged on the outer surface 30y of the laminate 30, it is possible to prevent the base material 41 from absorbing moisture and lowering the laminate strength of the laminate 30. can be done.

Further, in the present embodiment, the sealant layer 51 of the second film 50 contains a propylene/ethylene block copolymer. Therefore, the impact resistance of the second film 50 and the laminate 30 including the second film 50 can be enhanced. Therefore, even when the bag 10 is constructed using the laminate 30 having a two-layer structure, it is possible to prevent the bag 10 from breaking due to impact such as dropping.

Moreover, in the present embodiment, the adhesive layer 60 for joining the first film 40 and the second film 50 contains a larger amount of curing agent than conventionally. For example, the molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxyl groups of the polyol in the adhesive layer 60 is 3.5 or more. Therefore, the impact resistance of the laminate 30 having a two-layer configuration including the first film 40 and the second film 50 can be enhanced. Therefore, even when the bag 10 is constructed using the two-layer laminate 30, it is possible to prevent the bag 10 from breaking due to impact such as dropping.

Various modifications can be made to the above-described embodiment. 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 the corresponding portions in the above-described embodiment are used for the portions that can be configured in the same manner as in the above-described embodiment, Duplicate explanations are omitted. Further, when 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.

(Modification of bag)
In the present embodiment described above, an example in which the bag 10 is a gusseted bag has been shown, but the specific configuration of the bag 10 is not particularly limited. For example, as shown in FIG. 7, the bag 10 is a so-called four-sided seal formed by joining the inner surfaces of the surface film 14 and the back film 15 of the laminate 30 at the upper portion 11, the lower portion 12 and the side portions 13. It may be a bag.

Moreover, in the present embodiment described above, an example in which the first film 40 of the laminate 30 constituting the bag 10 has the printed layer 42 in addition to the base material 41 is shown. However, it is not limited to this, and the first film 40 may not have the printed layer 42 . Therefore, as the layer structure of the laminate 30, the following arrangement is also possible in order from the outer surface side to the inner surface side.
Base material/adhesive layer/sealant layer Base material/transparent gas barrier layer/adhesive layer/sealant layer

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the description of the Examples below as long as it does not exceed the gist thereof.

(Example 1)
[Production of laminate]
A film-like base material 41 including a plurality of layers 41a described in the above-described first configuration and produced by a casting method was prepared. The content of PBT in each layer 41a was 80%, the number of layers 41a was 1024, and the thickness of the substrate 41 was 15 μm. Subsequently, a printed layer 42 was formed on the film-like substrate 41 by gravure printing. As the ink for forming the printed layer 42, white ink Lamic FB manufactured by Dainichiseika Kogyo Co., Ltd. was used. Thus, the first film 40 having the substrate 41 and the printed layer 42 was produced. The thickness of the printed layer 42 was 1 μm.

Next, an adhesive composition was prepared by mixing a first composition containing a main agent and a solvent and a second composition containing a curing agent and a solvent. RU-40 manufactured by Rock Paint Co., Ltd. was used as the first composition containing a main agent and a solvent. RU-40 contains a polyester polyol. H-4 manufactured by Rock Paint Co., Ltd. was used as the second composition containing a curing agent and a solvent. H-4 contains an aliphatic isocyanate compound. The weight ratio of the second composition to the first composition was 0.15. In addition, the molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxyl groups of the polyol in the adhesive composition was 4.5.

The adhesive composition was then applied onto the printed layer 42 of the first film 40 . Subsequently, the adhesive composition applied on the first film 40 was dried to volatilize the solvent. Thereafter, the first film 40 and the second film 50 were laminated via the dried adhesive composition. Subsequently, the laminate was heated in an environment of 40° C. for 96 hours. Thereby, the adhesive composition was cured to obtain an adhesive layer 60 containing a cured product of a polyol and an aliphatic isocyanate compound. The thickness of the adhesive layer 60 was 3 μm.

Next, a second film 50 including a sealant layer 51 was prepared. As the sealant layer 51, an unstretched polypropylene film ZK93FM manufactured by Toray Advanced Film Co., Ltd. was used. The thickness of the sealant layer 51 was 70 μm.

[Evaluation of impact resistance]
Subsequently, the two laminates 30 were stacked and heated at 190° C. for 1 second to heat-seal the inner surfaces 30x of the laminates 30 . Next, the two heat-sealed laminates 30 were cut into a width of 15 mm to prepare a test piece 90 . 8 is a plan view showing the test piece 90, and FIG. 9 is a cross-sectional view of the test piece 90 of FIG. The test piece 90 has a width W3 of 15 mm and a length W4 of 50 mm. A seal portion is not formed. Subsequently, as shown in FIG. 14, the unsealed portion of one laminate 30 and the unsealed portion of the other laminate 30 are placed in opposite directions in a direction orthogonal to the surface direction of the seal portion 91 . , that is, to form a T-shape, the end of the unsealed portion of one laminate 30 and the end of the unsealed portion of the other laminate 30 are attached to jigs 92, respectively. , 93. At this time, the distance T between the jigs 92 and 93 in the direction orthogonal to the plane direction of the seal portion 91 was set to 40 mm. Subsequently, one jig 92 is struck with a hammer 94 from the first film 40 side of one laminate 30, and the impact when one laminate 30 and the other laminate 30 are separated. Strength was measured. As a measuring device, a digital impact tester manufactured by Toyo Seiki Seisakusho Co., Ltd. was used for evaluation. A 2J hammer was used for applying impact to the test piece 90 . As a result, the impact strength was 1056 kJ/m.

Subsequently, the puncture strength of the laminate 30 was measured according to JIS Z1707 7.4. As a measuring instrument, a Tensilon universal material testing machine RTC-1310 manufactured by A&D was used. Specifically, as shown in FIG. 11, a semicircular needle 100 having a diameter of 1.0 mm and a tip shape radius of 0.5 mm is applied to the test piece of the laminated body 30 in a fixed state from the outer surface 30y side. was pierced at a speed of 50 mm/min (50 mm per minute), and the maximum value of stress until the needle 100 penetrated the laminate 30 was measured. The maximum value of stress was measured for five or more test pieces, and the average value was defined as the puncture strength of the laminate 30 . The environment during the measurement was a temperature of 23° C. and a relative humidity of 50%. As a result, the puncture strength was 15N.

[Evaluation of drop strength]
Subsequently, the two laminates 30 were stacked and heated at 190° C. for 1 second to heat-seal the inner surfaces 30x of the laminates 30, and 200 g of water was filled as the content 18, as shown in FIG. A four-sided seal bag 10 was produced. The bag 10 had a height S1 of 180 mm and a width S2 of 130 mm.

After storing the bag 10 containing water overnight in an environment of 3° C., the bag 10 held so that the surface film 14 and the back film 15 are horizontal was dropped from a height of 120 cm, It was inspected whether or not the bag 10 would break. The bag 10 was repeatedly dropped five times, but no breakage was observed.

(Example 2)
A laminate 30 was produced in the same manner as in Example 1, except that the weight ratio of the second composition to the first composition was 0.2 when producing the adhesive composition. The molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxy groups of the polyol in the adhesive composition was 6.

Further, in the same manner as in Example 1, the inner surfaces 30x of the two laminates 30 were heat-sealed to prepare a test piece 90, and the impact strength was measured. As a result, the impact strength was 1137 kJ/m. Moreover, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 15N. Moreover, in the same manner as in Example 1, the drop strength of the bag 10 constructed using the laminate 30 was evaluated. The bag 10 was repeatedly dropped five times, but no breakage was observed.

(Example 3)
A laminate 30 was produced in the same manner as in Example 1, except that the substrate 41 having a PBT content of 70% in each layer 41a was used. Further, in the same manner as in Example 1, the inner surfaces 30x of the two laminates 30 were heat-sealed to prepare a test piece 90, and the impact strength was measured. As a result, the impact strength was 912 kJ/m. Moreover, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 13N. Moreover, in the same manner as in Example 1, the drop strength of the bag 10 constructed using the laminate 30 was evaluated. The bag 10 was repeatedly dropped five times, but no breakage was observed.

(Comparative example 1)
A laminate 30 was produced in the same manner as in Example 1, except that the weight ratio of the second composition to the first composition was 0.1 when producing the adhesive composition. The molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxy groups of the polyol in the adhesive composition was 3.

Further, in the same manner as in Example 1, the inner surfaces 30x of the two laminates 30 were heat-sealed to prepare a test piece 90, and the impact strength was measured. As a result, the impact strength was 758 kJ/m. Moreover, in the same manner as in Example 1, the drop strength of the bag 10 constructed using the laminate 30 was evaluated. As a result, the bag 10 broke at the fourth drop.

(Example 4)
A laminated body 30 was produced, which includes the substrate 41/adhesive layer 60/sealant layer 51 in order from the outer surface side to the inner surface side. As the base material 41, a film-like base material 41 including a plurality of layers 41a and produced by a casting method, as in the case of the first embodiment, was used. As the adhesive composition for forming the adhesive layer 60, as in Example 1, the first composition containing RU-40 and the second composition containing H-4 were used. was used. The weight ratio of the second composition to the first composition was 0.10 as in Comparative Example 1. The molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxy groups of the polyol in the adhesive composition was 3. As the sealant layer 51, unstretched polypropylene film ZK500 manufactured by Toray Advanced Film Co., Ltd. was used. ZK500 comprises the propylene-ethylene block copolymer and elastomer described above. The thickness of the sealant layer 51 was 70 μm.
It can be said that the laminate 30 of Example 4 is obtained by removing the print layer 42 from the laminate 30 of Comparative Example 1 and replacing the sealant layer 51 with ZK500.

In the same manner as in Example 1, the inner surfaces 30x of the two laminates 30 were heat-sealed to prepare a test piece 90, and the impact strength was measured. As a result, the impact strength was 946 kJ/m. Moreover, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 15N. Moreover, in the same manner as in Example 1, the drop strength of the bag 10 constructed using the laminate 30 was evaluated. The bag 10 was repeatedly dropped five times, but no breakage was observed.

(Example 5)
A laminate 30 was produced in the same manner as in Example 4 except that a film-like substrate 41 containing PBT and produced by a tubular method was used as the substrate 41 . The base material 41 was a single-layer film composed only of PBT and additives, and the thickness of the base material 41 was 15 μm.

In the same manner as in Example 1, the inner surfaces 30x of the two laminates 30 were heat-sealed to prepare a test piece 90, and the impact strength was measured. As a result, the impact strength was 838 kJ/m. Moreover, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 15N. Moreover, in the same manner as in Example 1, the drop strength of the bag 10 constructed using the laminate 30 was evaluated. The bag 10 was repeatedly dropped five times, but no breakage was observed.

(Comparative example 2)
A laminate 30 was produced in the same manner as in Example 5, except that an unstretched polypropylene film ZK93FM manufactured by Toray Advanced Film Co., Ltd. was used as the sealant layer 51 . The thickness of the sealant layer 51 was 70 μm.

In the same manner as in Example 1, the inner surfaces 30x of the two laminates 30 were heat-sealed to prepare a test piece 90, and the impact strength was measured. As a result, the impact strength was 502 kJ/m. Moreover, in the same manner as in Example 1, the drop strength of the bag 10 constructed using the laminate 30 was evaluated. As a result, the bag 10 broke at the fourth drop.

(Comparative Example 3)
A laminate 30 was produced in the same manner as in Comparative Example 2 except that a PET film E5100 (thickness: 12 μm) manufactured by Toyobo Co., Ltd. was used as the base material 41 . Further, in the same manner as in Example 1, the inner surfaces 30x of the two laminates 30 were heat-sealed to prepare a test piece 90, and the impact strength was measured. As a result, the impact strength was 537 kJ/m. Moreover, in the same manner as in Example 1, the drop strength of the bag 10 constructed using the laminate 30 was evaluated. As a result, the bag 10 broke at the fourth drop.

In the same manner as in Example 1, the inner surfaces 30x of the two laminates 30 were heat-sealed to prepare a test piece 90, and the impact strength was measured. As a result, the impact strength was 502 kJ/m. Moreover, in the same manner as in Example 1, the drop strength of the bag 10 constructed using the laminate 30 was evaluated. As a result, the bag 10 broke at the fourth drop. Moreover, the puncture strength of the laminate 30 was measured in the same manner as in Example 1. As a result, the puncture strength was 10N.

The layer structures and evaluation results of the laminates 30 of Examples 1 to 5 and Comparative Examples 1 to 3 are collectively shown in FIG. As can be seen from the comparison between Examples 1 to 5 and Comparative Examples 1 to 3, by constructing the bag 10 using the laminate 30 having an impact strength of 800 kJ/m or more, the bag 10 does not break even after being dropped five times. The bag 10 was able to have a drop strength of .

As can be seen from the comparison between Examples 4 and 5 and Comparative Examples 1 and 2, in order to increase the impact strength of the laminate 30, it is necessary for the sealant layer 61 to contain a propylene/ethylene block copolymer or an elastomer. is preferable. Further, as can be seen from the comparison between Examples 1 and 2 and Comparative Example 1, in order to increase the impact strength of the laminate 30, the ratio of the isocyanate group of the aliphatic isocyanate compound to the hydroxy group of the polyol in the adhesive composition is It can be said that a high molar ratio is preferable.

As shown in Comparative Example 3, when the substrate 41 was made of a PET film, the laminate 30 had a puncture strength of 10 N or less. On the other hand, as shown in Examples 1 to 5, when the substrate 41 is made of a film containing PBT as a main component, the puncture strength of the laminate 30 can be 11 N or more, more specifically 13 N or more. We were able to.

10 Bag 11 Upper portion 11a Upper seal portion 12 Lower portion 12a Lower seal portion 13 Side portion 13a Side seal portion 14 Surface film 15 Back film 16 Lower film 17 Storage portion 18 Contents 25 Easy-to-open means 26 Notch 30 Laminate 40 First Film 41 Base material 41a Layer 42 Printed layer 43 Transparent gas barrier layer 43a Transparent deposition layer 43b Transparent gas barrier coating film 50 Second film 51 Sealant layer 60 Adhesive layer

Claims (9)

A laminate,
substrate/adhesive layer/sealant layer,
substrate/printing layer/adhesive layer/sealant layer,
Substrate/transparent gas barrier layer/printing layer/adhesive layer/sealant layer, or
Consisting of base material/transparent gas barrier layer/adhesive layer/sealant layer,
The base material contains 51% by mass or more of polybutylene terephthalate,
The sealant layer comprises an unstretched polypropylene film,
The unstretched polypropylene film contains a propylene/ethylene block copolymer.fruit,
Requirement (A), (B) or (C) below is met,
(A) The adhesive layer contains a cured product of a polyol and an aliphatic isocyanate compound, and the molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxyl groups of the polyol is 3.5 or more. ,
(B) the sealant layer comprises the propylene/ethylene block copolymer and an elastomer;
(C) the laminate has an impact strength of 800 kJ/m or more;
laminate. The laminate according to claim 1, wherein the substrate contains 60% by mass or more of polybutylene terephthalate. The laminate according to claim 1 or 2, wherein the laminate has a puncture strength of 11 N or more. The laminate according to any one of claims 1 to 3, wherein the sealant layer contains 90% by mass or more of polypropylene. Claims 1 to 4, wherein the adhesive layer is a cured product of a polyol and an aliphatic isocyanate compound, and the molar ratio of the isocyanate group of the aliphatic isocyanate compound to the hydroxy group of the polyol is 3.5 or more. The laminate according to any one of the items. 6. The laminate according to any one of claims 1 to 5, wherein the base material has a multilayer structure containing 10 or more layers. 6. The laminate according to any one of claims 1 to 5, wherein the base material has a single layer structure having an IV value of 1.10 dl/g or more and 1.35 dl/g or less. 8. Laminate according to any one of the preceding claims, wherein the sealant layer comprises a thermoplastic elastomer. is a bag,
a laminate comprising an outer surface and an inner surface;
and a sealing portion that joins the inner surfaces of the laminate,
The laminate is sequentially formed from the outer surface side to the inner surface side.
substrate/adhesive layer/sealant layer,
substrate/printing layer/adhesive layer/sealant layer,
Substrate/transparent gas barrier layer/printing layer/adhesive layer/sealant layer, or
Consisting of base material/transparent gas barrier layer/adhesive layer/sealant layer,
The base material contains 51% by mass or more of polybutylene terephthalate,
The sealant layer comprises an unstretched polypropylene film,
The unstretched polypropylene film contains a propylene/ethylene block copolymer.fruit,
Requirement (A), (B) or (C) below is met,
(A) The adhesive layer contains a cured product of a polyol and an aliphatic isocyanate compound, and the molar ratio of the isocyanate groups of the aliphatic isocyanate compound to the hydroxyl groups of the polyol is 3.5 or more. ,
(B) the sealant layer comprises the propylene/ethylene block copolymer and an elastomer;
(C) the laminate has an impact strength of 800 kJ/m or more; bag.

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