Sealant film, laminate and packaging bag

Abstract

To provide a polyester-based sealant film which is excellent in seal strength and impact resistance.SOLUTION: A sealant film contains (A) a base polyester resin using an acid component containing a terephthalic acid and a diol component containing ethylene glycol, and (B) a polyester elastomer resin incompatible with (A) the base polyester resin, wherein (B) the polyester elastomer resin is a resin using an acid component containing an aromatic dicarboxylic acid and a diol component containing 1,4-butanediol and polyoxyalkylene glycol, and has a tensile elastic modulus at 23°C in at least one of a longitudinal direction and a width direction of 300-1,000 N / mm2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a sealant film, a laminate, and a packaging bag. [Background technology]

[0002] As part of efforts to address environmental issues, flexible packaging bags made of plastic film are becoming increasingly popular as a replacement for bottles and cans. In particular, self-standing packaging bags, or so-called standing pouches, are known as packaging bags that excel in terms of self-standing ability and large capacity, and are widely used as refill pouches for foods such as liquid soups and toiletries.

[0003] To accommodate larger capacity, polyolefin films such as polyethylene and polypropylene, which have excellent sealing properties and impact resistance, are generally used for the innermost sealant layer of packaging bags. However, polyolefin films have the disadvantage of absorbing the active ingredients and aroma components of the chemical products contained in them. Furthermore, because polyolefin films are flexible, they tend to bend when the contents are used and the volume is reduced, resulting in poor storage properties.

[0004] On the other hand, polyester films are known as sealant films that have low content adsorption and excellent rigidity. While polyester films have these excellent properties, they have the disadvantage of inferior sealing strength compared to polyolefin films. In response to this, Patent Document 1 attempts to obtain high sealing strength by controlling the heat capacity of crystalline fusion through the type and ratio of amorphous monomers used in the polyester film and film formation conditions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-188668 Summary of the Invention [Problem to be solved by the invention]

[0006] However, even with the method described in Patent Document 1, the seal strength of polyester films is still not sufficient, and their applications are limited to applications requiring relatively low levels of seal strength and impact resistance, such as lid materials for plastic containers and packaging bags for patch medicines.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide a polyester sealant film having excellent sealing strength and impact resistance, as well as a laminate and a packaging bag using the same. [Means for solving the problem]

[0008] In order to achieve the above object, the present disclosure provides a polyester elastomer resin (A) that contains an acid component containing terephthalic acid and a diol component containing ethylene glycol, and a polyester elastomer resin (B) that is incompatible with the base polyester resin (A), wherein the polyester elastomer resin (B) is a resin that contains an acid component containing an aromatic dicarboxylic acid and a diol component containing 1,4-butanediol and polyoxyalkylene glycol, and has a tensile modulus of elasticity of 300 to 1000 N / mm at 23°C in at least one of the longitudinal direction and the width direction. 2 The present invention provides a sealant film comprising:

[0009] The (B) polyester elastomer resin has a hard segment composed of an acid component containing an aromatic dicarboxylic acid and a diol component containing 1,4-butanediol, and a soft segment composed of a polyoxyalkylene glycol. The use of such a (B) polyester elastomer resin can improve the flexibility and impact resistance of the sealant film. Furthermore, since the (B) polyester elastomer resin having the specific structure is incompatible with the (A) base polyester resin, the sealant film can possess both the sealing performance of the (A) base polyester resin and the flexibility and impact resistance of the (B) polyester elastomer resin. If the (B) polyester elastomer resin is compatible with the (A) base polyester resin, the functions of each component are impaired, making it difficult to achieve both sealing performance and impact resistance. Furthermore, the sealant film has a tensile modulus of elasticity of 300 to 1,000 N / mm² at 23°C in at least one of the longitudinal and transverse directions. 2 By using the above-described structure, it is possible to obtain even better impact resistance. That is, according to the sealant film of the present disclosure, by containing the polyester elastomer resin (B) having the above-described specific structure in an incompatible state with the base polyester resin (A) and by adjusting the tensile modulus of elasticity to fall within a specific range, it is possible to achieve both excellent seal strength and excellent impact resistance. Furthermore, because the sealant film of the present disclosure is a polyester film, it can also be used for packaging bags that are self-supporting and have a large capacity, such as standing pouches.

[0010] In the sealant film, the diol component constituting the base polyester resin (A) may further contain at least one selected from the group consisting of aliphatic glycols other than ethylene glycol and alicyclic glycols, thereby further improving the seal strength of the sealant film.

[0011] In the sealant film, the content of the 1,4-butanediol constituting the (B) polyester elastomer resin may be 80 mol % or more based on the total amount of diol components in the (B) polyester elastomer resin, which facilitates increasing the incompatibility of the (B) polyester elastomer resin with the (A) base polyester resin and facilitates achieving both excellent seal strength and excellent impact resistance in the sealant film.

[0012] In the sealant film, the acid component constituting the polyester elastomer resin (B) may include at least one selected from the group consisting of terephthalic acid and isophthalic acid, thereby further improving the impact resistance of the sealant film.

[0013] In the sealant film, the content of the polyoxyalkylene glycol constituting the (B) polyester elastomer resin may be 35 to 55 mass % based on the total amount of the (B) polyester elastomer resin, which allows the sealant film to exhibit good film-forming properties and further improve flexibility and impact resistance.

[0014] The sealant film may satisfy at least one of the following conditions (1) and (2) when subjected to differential scanning calorimetry in the range of 20° C. to 250° C. This allows the sealant film to be sealed at the same temperature and with the same equipment as existing polyolefin-based films. (1) The glass transition temperature is 50°C or higher and 90°C or lower. (2) The melting peak temperature showing a heat of fusion of 0.5 J / g or more is 140°C or more and 180°C or less.

[0015] In the sealant film, the content of the (B) polyester elastomer resin may be 5 to 60% by mass based on the total mass of the sealant film, thereby further improving the flexibility and impact resistance of the sealant film.

[0016] The present disclosure also provides a laminate comprising a substrate layer and the sealant film, which can achieve excellent seal strength and excellent impact resistance.

[0017] In the laminate, the substrate layer may include a layer made of a polyester resin using an acid component containing terephthalic acid and a diol component containing ethylene glycol.

[0018] In the laminate, the substrate layer may include a vapor-deposited layer containing an inorganic oxide.

[0019] The present disclosure also provides a packaging bag obtained by laminating the sealant films of the laminate together, which has excellent sealing strength and excellent impact resistance.

[0020] The packaging bag may be self-supporting. [Effects of the Invention]

[0021] According to the present disclosure, it is possible to provide a polyester sealant film having excellent sealing strength and impact resistance, as well as a laminate and a packaging bag using the same. The sealant film and laminate of the present disclosure can also be used for packaging bags that are self-supporting and have a large capacity, such as standing pouches. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 shows a schematic cross-sectional view of a laminate according to one embodiment. [Figure 2] FIG. 2 shows a front view of a self-standing packaging pouch according to one embodiment. [Figure 3] FIG. 3 shows a cross-sectional view of the self-standing packaging bag taken along dashed line C in FIG. [Figure 4] FIG. 4 shows a schematic cross-sectional view of a sealant film according to one embodiment. [Figure 5]FIG. 5 shows atomic force microscope photographs of the cross sections of the sealant films obtained in Example 3 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present disclosure will be described in detail, with reference to the drawings as needed. However, the present disclosure is not limited to the following embodiments.

[0024] <Sealant film> The sealant film according to this embodiment is a polyester-based sealant film containing (A) a base polyester resin and (B) a polyester elastomer resin that is incompatible with (A) the base polyester resin.

[0025] The (A) base polyester resin is a resin using an acid component containing terephthalic acid and a diol component containing ethylene glycol. The acid component constituting the (A) base polyester resin preferably contains terephthalic acid as the main component. The diol component constituting the (A) base polyester resin preferably contains ethylene glycol as the main component. Here, the term "main component" refers to a component that accounts for 50 mol% or more of the total amount of the acid component or the total amount of the diol component.

[0026] (B) The polyester elastomer resin is a resin using an acid component containing an aromatic dicarboxylic acid and a diol component containing 1,4-butanediol and polyoxyalkylene glycol.

[0027] The sealant film is composed of an amorphous portion or an amorphous portion and a crystalline portion, and exhibits sealing strength due to the flow of the amorphous portion when heated above the glass transition temperature and the flow of the crystalline portion when heated above the melting point. The lower the glass transition temperature and melting point, the lower the sealing and bag-making process can be performed at a lower temperature or at a higher speed. The sealant film may have a glass transition temperature of 50 to 90°C and a melting point of 140 to 180°C. This allows the sealant film to be sealed at the same temperature and with the same equipment as existing polyolefin films.

[0028] Examples of means for controlling the glass transition temperature and melting point of the sealant film include a method of using 50 to 95 mol % of terephthalic acid and 50 to 5 mol % of other acid components (dicarboxylic acids) than terephthalic acid, based on the total amount of acid components constituting the (A) base polyester resin, and a method of using 50 to 95 mol % of ethylene glycol and 50 to 5 mol % of other diol components (diols) than ethylene glycol, based on the total amount of diol components constituting the (A) base polyester resin.These other components may be used for both the acid component and the diol component, or for either one of them.

[0029] Examples of dicarboxylic acids other than terephthalic acid used in the (A) base polyester resin include isophthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. These compounds may be used alone or in combination of two or more. In order to control the glass transition temperature and melting point of the sealant film within appropriate ranges, it is preferable to make the (A) base polyester resin amorphous. From this perspective, it is preferable to use terephthalic acid and isophthalic acid as dicarboxylic acids, with the content of isophthalic acid being in the range of 5 to 50 mol% based on the total amount of acid components. On the other hand, from the perspective of further improving the impact resistance of the sealant film, it is preferable to use only terephthalic acid as the acid component.

[0030] Examples of diols other than ethylene glycol used in the (A) base polyester resin include aliphatic glycols and alicyclic glycols. Specific examples of other diols include diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, and 1,4-cyclohexanedimethanol. These compounds may be used alone or in combination of two or more. Biomass-derived ethylene glycol and 2,2-dimethyl-1,3-propanediol may also be used. In order to control the glass transition temperature and melting point of the sealant film within appropriate ranges, it is preferable to make the (A) base polyester resin amorphous. From this viewpoint, it is preferable to use ethylene glycol and 1,4-cyclohexanedimethanol or 2,2-dimethyl-1,3-propanediol as diols, and to set the content of 1,4-cyclohexanedimethanol or 2,2-dimethyl-1,3-propanediol in the range of 15 to 50 mol % based on the total amount of diol components.

[0031] The base polyester resin (A) can be obtained by esterifying the acid component and diol component through dehydration condensation. The base polyester resin (A) does not contain an elastomer component and does not contain the polyoxyalkylene glycol used in the polyester elastomer resin (B).

[0032] Examples of aromatic dicarboxylic acids constituting the hard segments of the (B) polyester elastomer resin include terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. Examples of diol components (diols) constituting the hard segments of the (B) polyester elastomer resin include ethylene glycol, diethylene glycol, 1,4-butanediol, and 2,2-dimethyl-1,3-propanediol. These compounds may be used alone or in combination of two or more. The diols include at least 1,4-butanediol. The use of 1,4-butanediol ensures incompatibility with the (A) base polyester resin and improves the impact resistance of the sealant film. To further enhance incompatibility with the (A) base polyester resin, the content of 1,4-butanediol units may be 80 mol% or more based on the total amount of diol components in the (B) polyester elastomer resin. Furthermore, from the viewpoint of controlling the melting point of the sealant film within an appropriate range and enabling sealing at temperatures and with equipment similar to those of existing polyolefin-based films, it is preferable to combine terephthalic acid and isophthalic acid as aromatic dicarboxylic acids, and set the content of isophthalic acid in the range of 10 to 40 mol% based on the total amount of acid components.

[0033] Polyoxyalkylene glycol is used as a component constituting the soft segment of (B) polyester elastomer resin. Examples of polyoxyalkylene glycol include polyoxytrimethylene glycol and polyoxytetramethylene glycol. In particular, the use of polyoxytetramethylene glycol can further improve the incompatibility with (A) base polyester resin, as well as the seal strength and impact resistance.

[0034] From the viewpoint of further increasing the impact resistance of the sealant film, the number average molecular weight of the polyoxyalkylene glycol may be 500 to 3000 or 1000 to 2000. The number average molecular weight is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0035] The content of polyoxyalkylene glycol is preferably 35 to 55% by mass, more preferably 40 to 50% by mass, based on the total amount of (B) polyester elastomer resin. If this content is 35% by mass or more, the melting point of the sealant film tends to be easily lowered and flexibility and impact resistance tend to be further improved, while if it is 55% by mass or less, stickiness of the sealant film tends to be reduced and film formability tend to be improved.

[0036] The polyester elastomer resin (B) can be obtained by esterifying the acid component, diol component, and soft segment component through dehydration condensation. When synthesizing the polyester elastomer resin (B) through a transesterification reaction, the aromatic dicarboxylic acid can be used in the form of an aromatic dicarboxylic acid ester.

[0037] The content of (B) polyester elastomer resin in the sealant film is preferably 60% by mass or less, and more preferably 40% by mass or less, based on the total amount of the sealant film. A content of 60% by mass or less tends to easily prevent a decrease in transparency of the sealant film due to dispersion of the elastomer component, sticking of the sealant film to a cooling roll during extrusion, and fusion of films together. From the viewpoints of sealability, flexibility, and impact resistance, the content of (B) polyester elastomer resin is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more.

[0038] The degree of crystallization of the sealant film, or the so-called degree of crystallization, can be adjusted by changing the types and ratios of the components constituting the (A) base polyester resin and the (B) polyester elastomer resin, as well as the cooling temperature during film formation, to obtain different degrees of crystallinity even for the same material. Furthermore, the degree of crystallinity can also be adjusted by subjecting the formed sealant film to heat treatment or stretching treatment.

[0039] The (A) base polyester resin and (B) polyester elastomer resin used in the sealant film are incompatible. This incompatibility allows for the production of a sealant film that combines the sealing performance of the (A) base polyester resin with the flexibility and impact resistance of the (B) polyester elastomer resin. Conversely, if the two resins are highly compatible, the (B) polyester elastomer resin will interfere with the sealing of the (A) base polyester resin, resulting in a decrease in seal strength, and / or the (A) base polyester resin will interfere with the flexibility and impact resistance imparted to the sealant film by the (B) polyester elastomer resin, resulting in a decrease in flexibility and impact resistance.

[0040] Here, "incompatible" refers to a so-called sea-island structure in which one material exists as a dispersed phase in the matrix of the other main material, or a layered structure in which two types of materials each form a continuous phase.

[0041] FIG. 4 shows a schematic cross-sectional view of a sealant film according to one embodiment. "Incompatible" means that the other material is dispersed in a matrix of the main material in a sea-island structure with a maximum island diameter of 100 nm or more, or in a layered structure regardless of size. In addition, in differential scanning calorimetry (DSC), immiscibility can be determined when baseline shifts and / or peaks attributable to the respective resins are observed in the glass transition temperature (Tg) and / or melting point (Tm). In the sealant film 100 shown in FIG. 4, (B) polyester elastomer resin is dispersed in an incompatible state in a matrix of (A) base polyester resin 101.

[0042] The sealant film may contain components other than the (A) base polyester resin and the (B) polyester elastomer resin, provided that the effects of the present disclosure are not impaired. Examples of such components include resins other than the (A) base polyester resin and the (B) polyester elastomer resin, antistatic agents, UV absorbers, heat stabilizers, light stabilizers, release agents, antioxidants, lubricants, antiblocking agents, plasticizers, pigments, and dyes. The total content of these components may be 3% by mass or less, based on the total mass of the sealant film. In other words, the total content of the (A) base polyester resin and the (B) polyester elastomer resin in the sealant film may be 97% by mass or more, or even 100% by mass.

[0043] The sealant film according to this embodiment has a tensile modulus of elasticity at 23°C in at least one of the longitudinal direction and the width direction of 300 to 1000 N / mm 2 The tensile modulus is 1000N / mm 2 By keeping the tensile modulus at or below 300 N / mm, the flexibility and impact resistance of the sealant film are further improved, and the risk of the bag breaking when dropped can be further reduced. From the above perspective, a lower tensile modulus is desirable, but the lower limit currently available is 300 N / mm 2 In order to obtain the above effects more fully, the tensile modulus is set to 300 to 900 N / mm 2 300 to 600N / mm 2 300 to 500N / mm 2 may be.

[0044] The longitudinal direction of the sealant film refers to the flow direction during film formation, and the width direction refers to the direction perpendicular to the flow direction.

[0045] The sealant film according to this embodiment is attached to a polyethylene terephthalate film having a thickness of 12 to 50 μm, and the sealant films are heat-sealed at a sealing temperature of 200°C, a sealing time of 5 seconds, and a sealing pressure of 0.5 MPa. The seal strength is preferably 30 to 80 N / 15 mm, more preferably 35 to 80 N / 15 mm, and even more preferably 40 to 80 N / 15 mm. A seal strength of 30 N / 15 mm or greater reduces the risk of the seal retracting due to an impact from being dropped, resulting in leakage of the contents. While a higher seal strength is desirable, the upper limit currently achievable is approximately 80 N / 15 mm.

[0046] When differential scanning calorimetry (DSC) is performed on the sealant film according to this embodiment at temperatures between 20°C and 250°C, the sealant film preferably has a glass transition temperature of 50 to 90°C, more preferably 60 to 85°C, and even more preferably 70 to 80°C. A lower glass transition temperature is preferable, as it allows sealing at lower temperatures. However, at temperatures below 50°C, the amorphous portion begins to flow due to the glass transition, which can lead to blocking in the sealant film roll. Furthermore, when the base polyester resin (A) is primarily composed of ethylene terephthalate units, the upper limit of the glass transition temperature currently available is approximately 90°C.

[0047] When differential scanning calorimetry (DSC) is performed on the sealant film according to this embodiment from 20°C to 250°C, the melting peak temperature exhibiting a heat of fusion of 0.5 J / g or more is preferably 120°C to 190°C, more preferably 140°C to 180°C, and even more preferably 140°C to 170°C. By setting the melting peak temperature to 190°C or less, sealing can be performed at the same temperature and with the same equipment as existing polyolefin films. A lower melting peak temperature is desirable, but if it is 90°C or less, blocking or fusion in the sealant film roll may occur.

[0048] The tensile modulus, seal strength, glass transition temperature, and melting peak temperature can be controlled by the composition of the (A) base polyester resin, the composition of the (B) polyester elastomer resin, the compatibility between the (A) base polyester resin and the (B) polyester elastomer resin, the mixing ratio between the (A) base polyester resin and the (B) polyester elastomer resin, the crystallinity of the sealant film, etc. The tensile modulus, seal strength, glass transition temperature, and melting peak temperature can be specifically measured by the methods shown in the examples.

[0049] The sealant film can be formed by known methods such as a casting method or an inflation method. If the glass transition temperature is low, in the casting method, the molten resin may stick to the cooling roll that it first comes into contact with, causing transport problems. In addition, in the inflation method, the film folded at the pinch roll section may stick to itself and become inseparable. To prevent these problems from occurring, the glass transition temperature is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher.

[0050] The sealant film may be composed of a single layer or may contain two or more layers. When it contains two or more layers, it is sufficient that at least one of the outermost layers contains the above-mentioned (A) base polyester resin and (B) polyester elastomer resin, and all layers may contain the (A) base polyester resin and (B) polyester elastomer resin.

[0051] The thickness of the sealant film can be, for example, 5 to 200 μm, or may be 20 to 100 μm, from the viewpoint of obtaining excellent sealing strength and excellent impact resistance. When the sealant film includes two or more layers, the total thickness thereof may be within the above range.

[0052] <Laminate> 1 is a schematic cross-sectional view of a laminate according to one embodiment. A laminate 10 according to one embodiment includes a base layer 1, an adhesive layer 2, and a sealant film 3 in this order.

[0053] (base material layer) The substrate layer is a film (base film) that serves as a support. When the (A) base polyester resin used in the sealant film according to this embodiment has ethylene terephthalate units as its main constituent component, it is preferable that the substrate layer used in the laminate also has ethylene terephthalate units as its main constituent component. This makes the laminate closer to a single material, improving recyclability. From the viewpoint of improving recyclability, it is also preferable that the proportion of (B) polyester elastomer resin in the sealant film is low, and its content may be 20 mass% or less based on the total amount of the sealant film.

[0054] The substrate layer may be a single layer or multiple layers, but preferably includes at least a layer made of a polyester resin using an acid component containing terephthalic acid and a diol component containing ethylene glycol. The acid component preferably contains terephthalic acid as the main component, and the diol component preferably contains ethylene glycol as the main component. Here, the main component means a component that is contained in an amount of 50 mol% or more based on the total amount of the acid component or the total amount of the diol component.

[0055] The base layer may contain recycled polyester from the viewpoint of reducing the environmental load. Examples of recycled polyester include chemically recycled polyester obtained by chemically recycling a container made of polyester mainly composed of ethylene terephthalate units, and mechanically recycled polyester obtained by mechanically recycling a container made of polyester mainly composed of ethylene terephthalate units.

[0056] The substrate layer may be a gas barrier film having a vapor-deposited layer containing an inorganic oxide on at least one surface, for example, to improve gas barrier properties against water vapor and oxygen. By using a vapor-deposited layer of an inorganic oxide, high barrier properties can be achieved with a very thin layer that does not affect the recyclability of the laminate. Examples of inorganic oxides include aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. From the viewpoint of transparency and barrier properties, the inorganic oxide may be selected from the group consisting of aluminum oxide, silicon oxide, and magnesium oxide. The thickness of the vapor-deposited layer containing an inorganic oxide can be, for example, 5 nm to 100 nm, or 10 nm to 50 nm. A thickness of 5 nm or more facilitates the exertion of good barrier properties, while a thickness of 100 nm or less facilitates the maintenance of flexibility of the laminate. The vapor-deposited layer can be formed, for example, by physical vapor deposition, chemical vapor deposition, or the like.

[0057] When the substrate layer includes a plurality of film layers, the films may be the same or different. When the substrate layer includes a plurality of polyester film layers, at least one of the polyester films may have a vapor-deposited layer containing an inorganic oxide on its surface.

[0058] The thickness of the substrate layer can be, for example, 5 μm to 1 mm, or may be 5 to 800 μm, or may be 5 to 500 μm. When the substrate layer includes a plurality of the above films, the total thickness thereof may be within the above range.

[0059] (adhesive layer) Examples of adhesive components of the adhesive layer include two-component curing polyurethane adhesives in which a base agent such as polyester polyol, polyether polyol, or acrylic polyol is reacted with an aromatic or aliphatic isocyanate compound with two or more functional groups as a curing agent.

[0060] The adhesive layer can be formed by coating the adhesive component onto the substrate layer and then drying. When a polyurethane adhesive is used, aging the coating for at least 4 days at 40°C promotes the reaction between the hydroxyl groups of the base material and the isocyanate groups of the curing agent, resulting in strong adhesion.

[0061] The thickness of the adhesive layer can be set to 1 to 50 μm, and may be 1 to 20 μm, from the viewpoints of adhesiveness, followability, processability, and the like.

[0062] The laminate can be obtained by laminating the above-described base layer and sealant film via an adhesive layer by dry lamination, etc. When the base layer has a vapor deposition layer, the surface of the base layer facing the vapor deposition layer can be bonded to the sealant film via the adhesive layer.

[0063] <Packaging bag> The laminate according to this embodiment can be suitably used to form a packaging bag for packaging contents, such as liquids such as liquid seasonings, toiletries, soups, and liquid detergents, solids such as simmered dishes, and solid-liquid mixtures of liquids and solids such as curry.

[0064] Examples of packaging bags include flat pouch-shaped packaging bags and self-standing packaging bags (standing pouches).

[0065] The flat pouch-shaped packaging bag may be formed by folding one of the above laminates in half so that the sealant films face each other, and then heat-sealing three sides to form a bag shape, or by stacking two of the above laminates on top of each other so that the sealant films face each other, and then heat-sealing four sides to form a bag shape.

[0066] FIG. 2 is a front view of a self-standing packaging bag according to one embodiment, and FIG. 3 is a cross-sectional view of the self-standing packaging bag taken along dashed line C in FIG. 2. The self-standing packaging bag 20 includes a body portion 4 and a fold-in portion 5, which are sealed by a longitudinal edge portion 6, a boat-bottom-shaped bottom portion 7, and an upper seal portion 8. The self-standing packaging bag 20 is formed by arranging the sealant films of the two films 41, 42 that form the body portion 4 so that they face each other, inserting a film 51 that forms the fold-in portion 5 between the films 41, 42 while folding it in half with the sealant film facing outward, and then applying heat and pressure to the longitudinal edge portion 6, the boat-bottom-shaped bottom portion 7, and the upper seal portion 8. The laminate according to the present embodiment described above may be used for the films 41 and / or 42 in the body portion 4, or may be used for the film 51 in the fold-in portion 5. From the viewpoint of improving impact resistance, it is preferable to use the laminate for both the body portion 4 and the fold-in portion 5. [Example]

[0067] The present disclosure will be described in more detail with reference to the following examples, but the present disclosure is not limited to these examples.

[0068] Furthermore, with regard to the synthesized base polyester resins and polyester elastomer resins, the intrinsic viscosity was measured by dissolving a resin sample in a mixed solvent of phenol:tetrachloroethane = 60:40 (mass ratio) and then using an automatic viscosity measuring device (manufactured by Sun Electronics Industries, Ltd., product name: ALC-6C) equipped with an Ubbelohde viscometer temperature-controlled at 20°C, and the glass transition temperature and melting point were measured by differential scanning calorimetry (DSC).

[0069] [Synthesis of base polyester resin] 100 mol parts of terephthalic acid as the acid component, 94 mol parts of ethylene glycol and 35 mol parts of 2,2-dimethyl-1,3-propanediol as the diol components, were charged into a slurry preparation tank equipped with a stirrer and slurried at room temperature. The resulting slurry was transferred to an esterification reaction tank equipped with a rectification column and a stirrer, where an esterification reaction was carried out at 250°C. The water distilled during the reaction was removed from the system, thereby advancing the esterification reaction and obtaining an ester oligomer. The resulting ester oligomer was then added with 0.035 mol parts of triethyl phosphate as a thermal stabilizer and 0.027 mol parts of germanium dioxide as a polymerization catalyst, and transferred to a polycondensation reaction tank equipped with a pressure reducing device. After reducing the pressure inside the reaction tank over 1 hour, a polycondensation reaction was carried out at 280°C under a reduced pressure of 100 Pa or less until the desired melt viscosity was reached, yielding a base polyester resin with an intrinsic viscosity of 0.83 dL / g and a glass transition temperature of 73°C.

[0070] [Synthesis of polyester elastomer resin] <Elastomer A> 75 mol parts of dimethyl terephthalate and 25 mol parts of dimethyl isophthalate as acid components, 115 mol parts of 1,4-butanediol and 80 mol parts of ethylene glycol as diol components, were charged into a raw material preparation tank equipped with a stirrer and melted at 150° C. The resulting melt was sent to an esterification reaction tank equipped with a distillation column and a stirrer, and polyoxytetramethylene glycol with a number average molecular weight of 1500 as a soft segment was added so that the content was 40 mass% based on the total amount of the resulting polyester elastomer resin. Furthermore, 0.0005 mass parts of a hindered phenol-based antioxidant (trade name: AO-60, manufactured by ADEKA Corporation) based on the total amount of the resulting polyester elastomer resin, and 0.034 mol parts of tetrabutyl titanate as a transesterification catalyst were added, and a transesterification reaction was carried out while the produced methanol was distilled out of the system. After adding 0.086 mol of tetrabutyl titanate as a polycondensation catalyst, the mixture was transferred to a polycondensation reactor equipped with a pressure-reducing device. After reducing the pressure inside the reactor for 1.5 hours, the polycondensation reaction was carried out at 240°C under reduced pressure of 100 Pa or less until the desired melt viscosity was reached. This yielded a polyester elastomer resin (Elastomer A) with an intrinsic viscosity of 1.36 dL / g and a melting point of 154°C. The 1,4-butanediol content of Elastomer A was 82 mol% based on the total amount of diol components (including polyoxytetramethylene glycol). Note that some of the diol components were dispersed outside the reaction system during the polycondensation reaction; ethylene glycol dispersed more than 1,4-butanediol due to its lower boiling point.

[0071] <Elastomer B> A transesterification reaction and polycondensation reaction were carried out in the same manner as in the synthesis of Elastomer A, except that 195 parts by mole of 1,4-butanediol alone was charged as the diol component, to obtain a polyester elastomer resin (Elastomer B) with an intrinsic viscosity of 1.43 dL / g and a melting point of 164°C. The content of 1,4-butanediol constituting Elastomer B was 91 mol% based on the total amount of the diol components.

[0072] <Elastomer C> A polyester elastomer resin (Elastomer C) with an intrinsic viscosity of 1.35 dL / g and a melting point of 190°C was obtained by carrying out the transesterification reaction and polycondensation reaction in the same manner as in the synthesis of Elastomer B, except that 85 parts by mole of dimethyl terephthalate and 15 parts by mole of dimethyl isophthalate were added as the acid components, and polyoxytetramethylene glycol with a number average molecular weight of 1500 was added as the soft segment so that the content was 30% by mass based on the total amount of the resulting polyester elastomer resin. The content of 1,4-butanediol constituting Elastomer C was 94% by mole based on the total amount of the diol components.

[0073] <Elastomer D> A polyester elastomer resin (Elastomer D) with an intrinsic viscosity of 1.33 dL / g and a melting point of 175°C was obtained by carrying out the transesterification reaction and polycondensation reaction in the same manner as in the synthesis of Elastomer B, except that polyoxytetramethylene glycol with a number average molecular weight of 1500 was added as a soft segment so that the content was 30 mass% based on the total amount of the resulting polyester elastomer resin. The content of 1,4-butanediol constituting Elastomer D was 94 mol% based on the total amount of diol components.

[0074] <Elastomer E> A polyester elastomer resin (Elastomer E) with an intrinsic viscosity of 1.66 dL / g and a melting point of 155°C was obtained by carrying out the transesterification reaction and polycondensation reaction in the same manner as in the synthesis of Elastomer B, except that polyoxytetramethylene glycol with a number average molecular weight of 1500 was added as a soft segment so that the content was 50 mass% based on the total amount of the resulting polyester elastomer resin. The content of 1,4-butanediol constituting Elastomer E was 87 mol% based on the total amount of diol components.

[0075] <Elastomer F> A polyester elastomer resin (Elastomer F) with an intrinsic viscosity of 1.88 dL / g and a melting point of 142°C was obtained by carrying out the transesterification reaction and polycondensation reaction in the same manner as in the synthesis of Elastomer B, except that polyoxytetramethylene glycol with a number average molecular weight of 1500 was added as a soft segment so that the content was 60 mass% based on the total amount of the resulting polyester elastomer resin. The content of 1,4-butanediol constituting Elastomer F was 81 mol% based on the total amount of diol components.

[0076] <Elastomer G> 100 mol parts of terephthalic acid as the acid component and 112 mol parts of ethylene glycol as the diol component were charged into a slurry preparation tank equipped with a stirrer and slurried at room temperature. The resulting slurry was transferred to an esterification reaction tank equipped with a rectification column and a stirrer, where an esterification reaction was carried out at 250 °C. The water distilled during the reaction was removed from the system, thereby advancing the esterification reaction and obtaining an ester oligomer. Subsequently, 0.017 mol parts of triethyl phosphate as a thermal stabilizer was added to the resulting ester oligomer. A polyester polyol (trade name: Priplast 3199, manufactured by Croda) with a number average molecular weight of 2200 and composed of hydrogenated dimer acid and 1,4-butanediol as a soft segment was added so that the content based on the total amount of the resulting polyester elastomer resin was 30 mass%. Furthermore, 0.03 mol parts of tetrabutyl titanate was added as a polymerization catalyst, and the resulting mixture was transferred to a polycondensation reaction tank equipped with a pressure reducing device. After reducing the pressure inside the reactor for 1 hour, the polycondensation reaction was carried out at 265°C under a reduced pressure of 100 Pa or less until the specified melt viscosity was reached, yielding a polyester elastomer resin (Elastomer G) with an intrinsic viscosity of 0.75 dL / g and a melting point of 188°C. The content of 1,4-butanediol constituting Elastomer G was 3 mol% based on the total amount of diol components. 1,4-butanediol is also contained in Priplast 3199.

[0077] <Elastomer H> 70 mol parts of terephthalic acid as the acid component, 30 mol parts of sebacic acid as the soft segment, and 112 mol parts of ethylene glycol as the diol component were charged into a slurry preparation tank equipped with a stirrer and slurried at room temperature. The resulting slurry was transferred to an esterification reaction tank equipped with a rectification column and a stirrer, where the esterification reaction was carried out at 250 °C. The water distilled during the reaction was removed from the system, allowing the esterification reaction to proceed to yield an ester oligomer. The resulting ester oligomer was then added with 0.017 mol parts of triethyl phosphate as a thermal stabilizer and 0.03 mol parts of tetrabutyl titanate as a polymerization catalyst, and transferred to a polycondensation tank equipped with a pressure reducing device. After reducing the pressure inside the reaction tank for 1 hour, the polycondensation reaction was carried out at 265 °C under a reduced pressure of 100 Pa or less until the desired melt viscosity was reached, yielding a polyester elastomer resin (Elastomer H) with an intrinsic viscosity of 0.88 dL / g and a melting point of 173 °C.

[0078] [Production of sealant film, laminate and standing pouch] Example 1 90 parts by mass of base polyester resin pellets and 10 parts by mass of elastomer A pellets were dry blended and charged into a cast film-forming machine. The mixture was then extruded at 6 kg / h at 240°C using a single-screw extruder and quickly cooled on a 30°C cooling roll to produce an unstretched film. This produced a sealant film with a thickness of 50 μm.

[0079] A 50 μm thick stretched PET film, a crystalline polyester film, was prepared as the base layer of the laminate, and the above sealant film was attached to it by dry lamination to obtain a laminate. A general urethane resin adhesive was used as the adhesive for dry lamination. The amount of the urethane resin adhesive applied after drying was 3 g / m. 2 The thickness was adjusted to 3 μm.

[0080] The resulting laminate was used to form a body and a fold-in portion, yielding a stand-up pouch with the structure shown in Figure 2. The width (W in Figure 2) of the stand-up pouch was 130 mm, the height (H in Figure 2) was 220 mm, and the fold-in amount (distance between ab in Figure 2) was 40 mm. The sealing conditions during bag production were a sealing temperature of 200°C, a sealing time of 5 seconds, and a sealing pressure of 0.5 MPa.

[0081] Example 2 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 1, except that the blending amount of the base polyester resin pellets was 80 parts by mass and the blending amount of the elastomer A pellets was 20 parts by mass.

[0082] Example 3 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 1, except that the blending amount of the base polyester resin pellets was 60 parts by mass and the blending amount of the elastomer A pellets was 40 parts by mass.

[0083] Example 4 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 1, except that the blending amount of the base polyester resin pellets was 40 parts by mass and the blending amount of the elastomer A pellets was 60 parts by mass.

[0084] Example 5 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 2, except that elastomer A was changed to elastomer B.

[0085] Example 6 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 5, except that the blending amount of the base polyester resin pellets was 60 parts by mass and the blending amount of the elastomer B pellets was 40 parts by mass.

[0086] Example 7 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 2, except that Elastomer A was changed to Elastomer C.

[0087] Example 8 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 2, except that elastomer A was changed to elastomer D.

[0088] Example 9 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 2, except that Elastomer A was changed to Elastomer E.

[0089] Example 10 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 2, except that Elastomer A was changed to Elastomer F.

[0090] Example 11 A barrier film was prepared by forming a 10 nm thick silica vapor-deposited film as a barrier layer on one surface of a 12 μm thick stretched PET film, a crystalline polyester film. A 38 μm thick stretched PET film was attached to the non-silica vapor-deposited side of this barrier film using the dry lamination method. A general urethane resin adhesive was used as the adhesive for dry lamination, and the coating amount after drying was 3 g / m. 2 (thickness 3 μm). As a result, a base layer having a laminated structure of a 38 μm-thick stretched PET film / a 12 μm-thick stretched PET film / silica vapor deposition film was obtained. A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 2, except that a sealant film was attached to the silica vapor deposition surface of this base layer by dry lamination.

[0091] (Comparative Example 1) A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 2, except that Elastomer A was changed to Elastomer G.

[0092] (Comparative Example 2) A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 2, except that Elastomer A was changed to Elastomer H.

[0093] (Comparative Example 3) A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Comparative Example 2, except that the blending amount of the base polyester resin pellets was 60 parts by mass and the blending amount of the Elastomer H pellets was 40 parts by mass.

[0094] Comparative Example 4 A sealant film, a laminate, and a standing pouch were obtained in the same manner as in Example 1, except that the blending amount of the base polyester resin pellets was 100 parts by mass and the elastomer A pellets were not used.

[0095] [Evaluation method] The sealant film, laminate, and standing pouch obtained above were evaluated as follows. The results are shown in Tables 1 and 2.

[0096] (Film forming property) The state of the sealant film during cast film formation was evaluated according to the following criteria. A: There is no sticking to the cooling roll or fusion between films (blocking), so the film can be transported without any problems and has good film-forming properties. B: The film sticks to the cooling roll and fuses together (blocking), making it difficult to transport and resulting in poor film-forming properties.

[0097] (incompatibility) The sealant film obtained above was cooled to -120°C and then cut, and the resulting cross section was observed with an atomic force microscope (AFM). The observation results were evaluated according to the following criteria. A: As shown in the example in FIG. 4, the region where the polyester elastomer resin exists is observed separately from the region where the base polyester resin exists, and the base polyester resin and the polyester elastomer resin are in an incompatible state. B: No area where polyester elastomer resin is present is observed, and the base polyester resin and polyester elastomer resin are in a compatible state.

[0098] Figure 5(a) shows an atomic force microscope photograph of the cross section of the sealant film obtained in Example 3, and Figure 5(b) shows an atomic force microscope photograph of the cross section of the sealant film obtained in Comparative Example 1. The dark (black) parts in Figure 5(a) are (B) polyester elastomer resin 102, and the light parts are base polyester resin 101, and it can be seen that the two exist in an immiscible state in Figure 5(a). On the other hand, in Figure 5(b), it is indistinguishable between the dark and light parts, and it can be seen that the two are miscible.

[0099] (tensile modulus) The tensile modulus of elasticity in the machine direction (MD) and width direction (TD) of the sealant film was measured in accordance with JIS K 7127. The test piece width was 15 mm, the initial distance between the chucks was 100 mm, and the test speed was 300 mm / min. The data obtained by measurement in an environment of 23°C was linearly approximated between loads of 2 N and 10 N, and the slope of this line was taken as the tensile modulus of elasticity.

[0100] (Differential scanning calorimetry (DSC)) Differential scanning calorimetry (DSC) was performed on the sealant film in accordance with JIS K7121-1987. The film was heated from 20°C to 250°C at a temperature increase rate of 10°C / min, and the glass transition temperature and peak melting temperature were read from the resulting curve. If the heat of fusion was less than 0.5 J / g, the peak melting temperature could not be read.

[0101] (transparency) The haze of the sealant film was measured in accordance with JIS K7105 using a haze meter (product name: NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) The measured values ​​were evaluated according to the following criteria. A: Haze less than 20% B: Haze 20% or more

[0102] (Seal strength) The sealant films of the laminate were placed facing each other and heat-sealed at a sealing temperature of 200°C, a sealing time of 5 seconds, a sealing pressure of 0.5 MPa, and a sealing width of 10 mm. The heat-sealed film was then cut into a 15 mm wide x 100 mm test piece. This test piece was subjected to T-peel testing at a tensile speed of 300 mm / min in an environment of 23°C using a tensile tester (Shimadzu Corporation), and the seal strength of the heat-sealed portion was measured.

[0103] (Drop bag test) The standing pouches prepared in the Examples and Comparative Examples were filled with 100 mL or 150 mL of water as the contents, and the top of the pouch was heat-sealed under conditions of a sealing temperature of 200°C, a sealing time of 5 seconds, and a sealing pressure of 0.5 MPa to obtain a standing pouch containing the contents. The contents-filled standing pouches were then stored in a 5°C environment for 24 hours, after which they were dropped vertically from a height of 1 m with the folded portion facing downwards, and the number of times they were dropped was counted until they broke. Breakage mainly occurred near the boundary between the heat-sealed and non-heat-sealed portions. However, in some pouches with low seal strength, breakage occurred due to peeling of the heat-sealed portion. Twenty samples were evaluated under the same conditions and evaluated according to the following criteria. A: The pouch survival rate (the percentage of pouches remaining without breaking) after 20 drops is 90% or more. B: Pouch remaining rate after 20 drops is 50% or more but less than 90% C: Less than 50% of the pouch remains after 20 drops

[0104] [Table 1]

[0105] [Table 2] [Industrial Applicability]

[0106] The sealant film according to the present disclosure makes it possible to obtain laminates and packaging bags using polyester resins that have excellent sealing strength and impact resistance. Furthermore, it is also possible for the films constituting the laminate to be substantially all polyester films. Such laminates can be considered as mono-material packaging materials, and are expected to have excellent recyclability. [Explanation of symbols]

[0107] 1...base material layer, 2...adhesive layer, 3...sealant film, 4...body portion, 5...folded portion, 6...longitudinal edge portion, 7...bottom, 8...top seal portion, 10...laminated body, 20...self-standing packaging bag, 41, 42, 51...film, 100...sealant film, 101...(A) base polyester resin, 102...(B) polyester elastomer resin.

Claims

1. (A) a base polyester resin using an acid component containing terephthalic acid and a diol component containing ethylene glycol; (B) a polyester elastomer resin that is incompatible with the (A) base polyester resin; Contains the polyester elastomer resin (B) is a resin using an acid component containing an aromatic dicarboxylic acid and a diol component containing 1,4-butanediol and a polyoxyalkylene glycol, the acid component constituting the polyester elastomer resin (B) contains terephthalic acid and isophthalic acid, the content of the isophthalic acid constituting the (B) polyester elastomer resin is 10 to 40 mol% based on the total amount of acid components of the (B) polyester elastomer resin, Tensile modulus at 23°C in at least one of the longitudinal and transverse directions is 300 to 1000 N / mm ２ That is, sealant film.

2. 2. The sealant film according to claim 1, wherein the diol component constituting the base polyester resin (A) further contains at least one selected from the group consisting of aliphatic glycols other than ethylene glycol and alicyclic glycols.

3. The sealant film according to claim 1 or 2, wherein the content of the 1,4-butanediol constituting the polyester elastomer resin (B) is 80 mol% or more based on the total amount of diol components in the polyester elastomer resin (B).

4. The sealant film according to any one of claims 1 to 3, wherein the content of the polyoxyalkylene glycol constituting the (B) polyester elastomer resin is 35 to 55 mass% based on the total amount of the (B) polyester elastomer resin.

5. The sealant film according to any one of claims 1 to 4, which satisfies at least one of the following conditions (1) and (2) when subjected to differential scanning calorimetry in the range of 20 ° C to 250 ° C. (1) The glass transition temperature is 50°C or higher and 90°C or lower. (2) The melting peak temperature showing a heat of fusion of 0.5 J / g or more is 140°C or more and 180°C or less.

6. The sealant film according to any one of claims 1 to 5, wherein the content of the polyester elastomer resin (B) is 5 to 60 mass% based on the total amount of the sealant film.

7. A laminate comprising a substrate layer and the sealant film according to any one of claims 1 to 6.

8. The laminate according to claim 7 , wherein the substrate layer comprises a layer made of a polyester resin using an acid component containing terephthalic acid and a diol component containing ethylene glycol.

9. The laminate according to claim 7 or 8, wherein the substrate layer comprises a vapor-deposited layer containing an inorganic oxide.

10. A packaging bag obtained by bonding together the sealant films of the laminate according to any one of claims 7 to 9.

11. The packaging bag according to claim 10, which is self-supporting.

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