JP2018177317A - Bag-in-box inner bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bag-in-box inner bag which has sufficient heat seal energy without damaging the taste or flavor of the contents.SOLUTION: The bag-in-box inner bag of the present invention includes a polyester sealant at the inmost layer, and the heat seal energy when the polyester sealants are sealed with each other at 140°C for one second is 0.10 J/15 mm to 0.5 J/15 mm.SELECTED DRAWING: None

Description

  The present invention relates to an inner bag for bag-in-box. In particular, the present invention relates to a bag-in-box inner bag having a polyester-based sealant in the innermost layer so as not to impair the flavor of food and drink such as liquor and fruit juice beverages and seasonings.

  Conventionally, gallon cans, drums, plastic tanks, etc. have been used to fill, store and transport fluids such as liquids and powders. However, from the viewpoint of waste disposal and volume reduction after use, a container called a bag-in-box, which is made of a plastic inner bag and a cardboard outer bag, is used. The bag-in-box has a volume of about 1 L to 20 L, and is used not only for business but also for general consumers as a container for food and drink and medicine.

  As the inner bag of the bag-in-box, a bag is used in which a blow-molded plastic or plastic film or sheet is heat sealed or the like. In the case of forming a bag by heat sealing a plastic film or sheet, it is necessary to seal the films of the innermost layer, and in Patent Document 1, for example, an olefin based sealant is used. However, when an olefin-based sealant is used in the innermost layer, there is a problem that the low molecular weight component of the olefin-based plastic is eluted in the content. In particular, when the contents are food and drink, the taste and taste of the contents are impaired (so-called poly odor). Further, when the content contains an aroma component such as limonene, it is adsorbed by the olefin sealant in the innermost layer, so that the flavor is also impaired.

  On the other hand, Patent Document 2 discloses a bag-in-box in which the material of the inner layer of the bag-like container main body with which the contents are in contact and the material of the pouring plug are polyethylene terephthalate. When polyethylene phthalate is used as in Patent Document 2, the smell of polyethylene phthalate is transferred to fruit juice beverage as compared with the conventional bag-in-box bag-like container whose content contact surface is polyethylene, limonene for fruit juice beverage It is stated that the polyethylene terephthalate is not adsorbed to polyethylene terephthalate, and the change in odor and taste of the contents is very small.

  Further, Patent Document 3 discloses a film including a seal portion to which heat sealability is imparted by irradiating a predetermined region of a biaxially oriented polyester surface with a laser beam, and a packaging bag using the same.

Patent No. 4931062 gazette Japanese Utility Model Application Publication No. 6-61760 Unexamined-Japanese-Patent No. 2017-19894

  However, in the case of polyethylene terephthalate, heat seal energy is insufficient, and it can not sufficiently withstand impact due to dropping from a high place, for example, about 3 m. In addition, it has been found that when the heat seal strength is improved as in Patent Document 3 described above, the heat seal energy is insufficient when the contents are liquid as in the bag-in-box, and the same problem as described above occurs.

  This invention is made in view of the said situation, The objective is to provide the bag-in-box inner bag which has sufficient heat seal energy, without impairing the taste and flavor of a content.

The inventors of the present invention have made studies to provide an inner bag for a bag-in-box that can sufficiently withstand, in particular, an impact due to transportation or dropping. As a result, it has been found that when a bag-in-box inner bag having a predetermined heat-sealing energy is used, the impact due to drop etc. is remarkably improved as compared to the bag-in-box inner bag which only enhances the heat seal strength. , Completed the present invention.
The constitution of the present invention is as follows.
1. A polyester-based sealant is provided in the innermost layer, and the heat sealing energy when the polyester-based sealants are sealed at 140 ° C. and one second is 0.10 J / 15 mm to 0.5 J / 15 mm. Inner bag for bag-in-box.
2. The inner bag for a bag-in-box according to the above 1, wherein the heat seal strength when sealing the polyester-based sealants at 140 ° C. for 1 second is 5 N / 15 mm or more and 30 N / 15 mm or less.
3. The inner bag for a bag-in-box according to the above 1 or 2, wherein the heat seal elongation is 10 mm or more and 30 mm or less when the polyester sealants are sealed at 140 ° C. for 1 second.
4. The polyester according to any one of the above 1 to 3, which comprises at least one selected from the group consisting of neopentyl glycol, 1,4-cyclohexanedimethanol, isophthalic acid and diethylene glycol as a polyester component constituting the polyester-based sealant. Inner bag for bag in box.
5. The inner bag for bag-in-box according to any one of the above 1 to 4, wherein the polyester component of the polyester-based sealant further comprises 1,4-butanediol.
6. The inner bag for bag-in-box according to any one of the above 1 to 5, wherein the thickness of the polyester-based sealant is 9 μm to 120 μm.
7. The inner bag for bag-in-box according to any one of the above 1 to 6, wherein at least one layer of a polyamide-based film is laminated on the outside of the polyester-based sealant.
8. The inner bag for bag-in-box according to any one of the above 1 to 7, further comprising a gas barrier film on the outside of the polyester-based sealant.
9. A polyester film for the innermost layer of a bag-in-box inner bag, which has a heat seal energy of 0.10 J / 15 mm or more and 0.5 J / 15 mm or less when polyester-based sealants are sealed at 140 ° C. for 1 second.

  Since the bag-in-box inner bag of the present invention has a predetermined polyester-based sealant in the innermost layer, an inner bag having high heat sealing energy can be obtained without impairing the taste and flavor of the contents. Therefore, it is possible to endure impact due to falling from a very high level and the like, and transport under extremely severe conditions can be realized with certainty.

1 shows the polyester film No. 1 in Table 2. It is a figure which shows the calculation method of heat seal energy in 1, heat seal strength, and heat seal elongation. 2 shows the polyester film No. 1 in Table 2. It is a figure which shows the heat seal test result in 5. FIG. FIG. 3 is a schematic cross-sectional view of the bag-in-box inner bag of the present invention. FIG. 4 is a sectional view of the laminated structure in which the heat seal portion 3 is enlarged along the broken line 4 in FIG.

  The bag-in-box inner bag according to the present invention has a polyester-based sealant in the innermost layer, and the heat-sealing energy is 0.10 J / 15 mm or more when the polyester-based sealants are sealed at 140 ° C. for 1 second. .5 J / 15 mm or less.

1. Properties of Polyester-Based Sealant First, the properties necessary for the polyester-based sealant used in the bag-in-box of the present invention will be described.

1.1 Heat Sealing Energy The above-mentioned polyester sealants satisfy heat sealing energy of 0.10 J / 15 mm or more and 0.5 J / 15 mm or less when the polyester sealants are heat sealed at a temperature of 140 ° C. and a sealing time of 1 second. .

  Here, heat seal energy is a value indicating the area of a heat seal curve (integrated value of heat seal elongation and heat seal strength) obtained by bonding polyester-based sealants under the above conditions in terms of energy per 15 mm. It means the absorbed energy until the heat seal part breaks (or yields). For reference, polyester film No. 1 in Table 2 described later in FIG. The heat seal curve in 1, and the calculation method of heat seal energy, heat seal strength, and heat seal elongation are shown. The start point and the end point of the heat seal elongation used for the calculation of the area were set to 5% of the maximum value of the heat seal strength. Detailed measurement conditions of the heat seal energy are described in the section of Examples described later.

  If the heat seal energy is less than 0.10 J / 15 mm, the seal portion is easily peeled off, so the bag is broken in the drop bag evaluation test described later, and the contents can not be stored stably. . The heat seal energy is preferably 0.15 J / 15 mm or more, more preferably 0.2 J / 15 mm or more. The heat seal energy is preferably as large as possible, but the upper limit obtained at present is about 0.5 J / 15 mm. If the heat sealing energy is 0.5 J / 15 mm, it can sufficiently withstand the impact and the like when transporting the bag-in-box.

1.2 Heat Sealing Strength The polyester sealant preferably has a heat sealing strength of 5 N / 15 mm to 30 N / 15 mm when heat sealing polyester-based sealants at a temperature of 140 ° C. and a sealing time of 1 second. As described above, in the present invention, the heat seal energy represented by the product of the heat seal strength and the heat seal elongation is defined within a predetermined range, and it has a certain level of heat seal strength if the heat seal energy is satisfied. The heat seal energy and / or the heat seal elongation, which will be described later, increase as the heat seal energy increases, which is preferable as a bag-in-box inner bag. The heat seal strength is preferably 7 N / 15 mm or more, more preferably 9 N / 15 mm or more. The larger the heat seal strength, the better, but the upper limit obtained at present is about 30 N / 15 mm.

1.3 Heat Seal Elongation The polyester sealant preferably has a heat seal elongation of 10 mm or more and 30 mm or less when the polyester sealants are heat sealed at a temperature of 140 ° C. and a sealing time of 1 second. The heat seal elongation is more preferably 15 mm or more, further preferably 20 mm or more. The larger the heat seal elongation, the better, but the upper limit obtained at present is about 30 mm.

1.4 Haze The polyester-based sealant preferably has a haze of 1% or more and 15% or less. When the haze exceeds 15%, the transparency of the film is deteriorated, and therefore, the visibility of the contents is deteriorated when used as a packaging material such as a bag. The upper limit of the haze is more preferably 13% or less, and still more preferably 11% or less. The lower the haze, the higher the transparency and the better. However, the lower limit is 1% according to the current state of the art, and 2% or more is sufficient for practical use.

1.5 Thickness unevenness in the longitudinal direction The polyester sealant preferably has a thickness unevenness of 18% or less when the measurement length is 10 m in the longitudinal direction. If the thickness unevenness in the longitudinal direction exceeds 18%, the thickness accuracy of the sealant will be extremely deteriorated, and not only the heat seal energy will vary, but also problems such as uneven thickness and slack in the roll wound up as a product Occurs. Furthermore, when laminating with another film, unevenness in lamination (variation in the amount of applied adhesive, etc.) occurs. The thickness unevenness in the longitudinal direction is more preferably 16% or less, and still more preferably 14% or less. The smaller the thickness unevenness in the longitudinal direction, the better, but the lower limit is considered to be about 1% from the performance of the film forming apparatus.

1.6 Thickness unevenness in the width direction The polyester sealant preferably has a thickness unevenness of 18% or less when the measurement length is 1 m in the width direction. If the thickness unevenness in the width direction exceeds 18%, the same problem as the thickness unevenness in the longitudinal direction described above occurs. The thickness unevenness in the width direction is more preferably 16% or less, and still more preferably 14% or less. The thickness unevenness in the width direction is preferably as close to 0% as possible, but the lower limit is considered to be 1% from the performance of the film forming apparatus and the ease of production.

1.7 Thickness The thickness of the polyester-based sealant is not particularly limited, but is preferably 9 μm or more and 120 μm or less. If the thickness of the sealant is smaller than 9 μm, the heat seal energy and the heat seal strength may be insufficient. From the above point of view, although the thickness of the sealant may be thicker than 120 μm, the use weight of the sealant increases and the chemical cost becomes high. The thickness of the sealant is more preferably 12 μm or more and 100 μm or less, and still more preferably 15 μm or more and 80 μm or less.

2. Film-forming conditions of polyester-based sealant The polyester-based sealant used for the bag-in-box inner bag of the present invention is obtained by melt-extruding the polyester raw material described below with an extruder to form a non-oriented film, be able to. The sealant may adopt any stretching method such as non-stretching, uniaxial stretching, or biaxial stretching, but in order to keep the heat seal energy high, it is non-stretching or when stretching it is a stretching ratio (biaxial stretching In this case, it is preferable to make the area magnification factor of integrating the first axis and the second axis 3 times or less. The polyester is obtained by containing an appropriate amount of a monomer that can be an amorphous component. Moreover, 2 or more types of chip-like polyester can be mixed and used as a raw material of a sealant.

2.1 Polyester raw material The polyester which is a raw material of the polyester-based sealant used for the innermost layer in the bag-in-box inner bag of the present invention contains an ethylene terephthalate component and an amorphous component. Furthermore, the above-mentioned polyester may contain components other than these.

(Ethylene terephthalate)
The polyester raw material used in the present invention contains an ethylene terephthalate unit as a main component. Here, "include as main component" means that 50% by mole or more of ethylene terephthalate units is contained in 100% by mole of all ester units. 55 mol% or more is preferable and 60 mol% or more of an ethylene terephthalate unit is preferable. The upper limit of the ethylene terephthalate unit is preferably 85 mol% or less, more preferably 80 mol% or less, and still more preferably 75 mol% or less.

  If the ethylene terephthalate unit is less than 50 mol%, the mechanical strength and heat resistance of the sealant may be insufficient. On the other hand, when the content of the ethylene terephthalate unit is more than 85 mol%, the content of the amorphous component relatively decreases, and the heat seal energy decreases.

(Amorphous component)
The polyester raw material used in the present invention contains an amorphous component (amorphous alcohol component and an amorphous acid component). The presence of the amorphous component improves the heat seal energy of the polyester-based sealant.

  Examples of the monomer of the amorphous acid component (carboxylic acid component) include isophthalic acid, 1,4-cyclohexanedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid.

  Further, as a monomer of the amorphous alcohol component (diol component), for example, neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol, 2,2-diethyl 1,3-propanediol, 2-n-butyl-2- Ethyl 1,3-propanediol, 2,2-isopropyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, hexanediol and the like can be mentioned.

  Among the above amorphous components, it is preferable to use any one or more of isophthalic acid, neopentyl glycol, 1,4-cyclohexanedimethanol, and diethylene glycol, thereby further enhancing the non-crystallinity of the polyester-based sealant. Thus, the heat sealing energy of the polyester sealant can be easily secured to a predetermined level (0.10 J / 15 mm or more). It is more preferable to use any one or more of neopentyl glycol and 1,4-cyclohexanedimethanol among the above, and it is particularly preferable to use neopentyl glycol.

  1 mol% or more is preferable and, as for the ratio of the said amorphous component, 2 mol% or more is more preferable. When the proportion of the amorphous component is less than 1 mol%, the sealant is difficult to soften or melt during heat sealing, and it becomes difficult to make the heat seal energy 0.10 J / 15 mm or more. On the other hand, the upper limit of the proportion of the amorphous component is not particularly limited from the above viewpoint, but is preferably 30 mol% or less. If the proportion of the amorphous component is too large, heat sealing of the sealant can be easily performed, but the heat resistance of the sealant decreases, so that the periphery of the seal portion is blocked during heat sealing (heat conduction from the heating member As a result, the phenomenon of being sealed in a wider range than the intended range is made, and appropriate heat sealing becomes difficult.

(Components other than ethylene terephthalate and amorphous component)
The polyester raw material used in the present invention may further contain components other than the above-mentioned ethylene terephthalate and amorphous components. For example, examples of the dicarboxylic acid component constituting the polyester include aromatic dicarboxylic acids such as orthophthalic acid; aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid and the like; alicyclic dicarboxylic acids and the like. However, since the tensile strength at break is reduced when a trivalent or higher polyvalent carboxylic acid (for example, trimellitic acid, pyromellitic acid, anhydrides thereof, etc.) is contained, it is preferable not to contain it in polyester.

  Moreover, as diol components other than ethylene glycol which comprises polyester, For example, long-chain diols, such as a 1, 4- butanediol; Aliphatic diols, such as hexanediol; Aromatic system diols, such as bisphenol A, etc. are mentioned. However, tensile fracture strength decreases when containing a diol having 8 or more carbon atoms (for example, octanediol etc.) or a polyhydric alcohol having 3 or more valences (for example trimethylolpropane, trimethylolethane, glycerin, diglycerin etc.) It is preferable not to contain in polyester because

  It is preferable to use 1, 4- butanediol among components other than the ethylene terephthalate mentioned above and an amorphous component. This is because 1,4-butanediol is very useful for lowering the melting point of polyester-based sealants to raise the level of heat seal energy to the desired level of 0.10 J / 15 mm or more. The preferred content of 1,4-butanediol in the total alcohol component and the total acid component is 5 mol% or more and 30 mol% or less, more preferably 8 mol% or more and 27 mol% or less.

  The polyester raw material used for this invention can add various additives as needed. The additive is not particularly limited, and known additives such as waxes, antioxidants, antistatic agents, crystal nucleating agents, viscosity reducing agents, heat stabilizers, coloring pigments, coloring inhibitors, UV absorbers, etc. Can be mentioned.

  Further, in order to improve the slipperiness of the film, it is preferable to add fine particles acting as a lubricant at least on the surface layer of the polyester film. As microparticles | fine-particles, both inorganic type microparticles | fine-particles and organic type microparticles | fine-particles can be selected arbitrarily. For example, as the inorganic fine particles, silica, alumina, titanium dioxide, calcium carbonate, kaolin, barium sulfate and the like can be mentioned. Further, as the organic fine particles, acrylic resin particles, melamine resin particles, silicone resin particles, crosslinked polystyrene particles and the like can be mentioned. It is preferable that the average particle diameter of the said microparticles | fine-particles exists in the range of about 0.05-3.0 micrometers when it measures with a Coulter counter.

  The method for blending the above-mentioned fine particles in the polyester-based sealant is not particularly limited. For example, although it can be added at any stage of producing a polyester-based resin, polycondensation is performed after the esterification stage or transesterification reaction completion. It is preferable to add as a slurry dispersed in ethylene glycol or the like at the stage before the start of the reaction to advance the polycondensation reaction. In addition, a method of blending a slurry of particles dispersed in ethylene glycol, water, or other solvent with a polyester resin material using a vented kneading extruder, or kneading extrusion of dried particles and polyester resin material There is also a method of blending using a machine.

2.2 Film-forming conditions A polyester-based sealant is formed into a film as follows using the above-mentioned polyester raw material. In order to keep the heat seal energy high, no stretching, or a stretching ratio in the case of stretching (in the case of uniaxial stretching, this is the stretching ratio at the time of stretching; in the case of biaxial stretching, the uniaxial and biaxial axes were integrated It is preferable to control the area magnification factor to 3 times or less. In order to keep the heat seal energy higher, it is more preferable to be non-stretching.

2.2 (a) Melt extrusion When melt-extruding the raw material resin, it is preferable to dry the polyester raw material of each layer using a dryer such as a hopper dryer or paddle dryer, or a vacuum dryer. Thus, after drying the polyester raw material of each layer, it fuse | melts at temperature of 200-300 degreeC using an extruder, and extrudes as laminated | multilayer film. The extrusion can adopt any existing method such as a T-die method or a tubular method.

  Thereafter, by quenching the extruded film, a non-oriented film can be obtained. In addition, as a method of quenching the molten resin, preferably employed is a method of obtaining a substantially non-oriented resin sheet by casting the molten resin from a die onto a rotating drum and rapidly solidifying it. As described above, the sealant may be unstretched, or in the longitudinal (longitudinal) direction, in the lateral (width) direction, or in one of these biaxial directions within a range that satisfies a predetermined heat sealing energy. It may be stretched.

  In the following, although sequential biaxial stretching by transverse stretching-longitudinal stretching in which transverse stretching is performed first and then longitudinal stretching will be described, it is not limited to this, and longitudinal stretching-transverse stretching in which the order is reversed Also, it can be adopted because only the main orientation direction changes. Alternatively, simultaneous biaxial stretching can also be employed. When secondary stretching is performed, it is preferable to control the area magnification (the sum of the first and second axes) to be 3 times or less as described above, whereby the heat seal energy can be improved. The area magnification is more preferably 2.8 times or less. The lower limit is not particularly limited, but in consideration of improvement in productivity by stretching, etc., it is preferably about 1.1 times or more.

2.2 (b) Transverse Stretching First, stretching in the transverse direction is performed. Stretching in the transverse direction is preferably performed at 65 to 100 ° C. in a state in which both ends of the film in the width direction are gripped by clips in a tenter (first tenter). If the stretching temperature is lower than 65 ° C., oriented crystallization of the film by transverse stretching is promoted, so there is a possibility that the film may be easily broken not only in transverse stretching but also in longitudinal stretching in a later step. On the other hand, if the transverse stretching temperature is higher than 100 ° C., roll contamination may occur at an early stage in continuous production. The lateral stretching ratio in biaxial stretching is not particularly limited as long as the area ratio is controlled to be 3 times or less, but it is preferably about 1.1 to 2.8.

  It is preferable to perform preheating before stretching in the transverse direction, and it is preferable to perform preheating until the film surface temperature reaches 60 ° C. to 100 ° C.

2.2 (c) Longitudinal Stretching Subsequently, longitudinal stretching is performed. In the longitudinal stretching step, first, a laterally uniaxially stretched film is introduced into a longitudinal stretcher in which a plurality of roll groups are continuously disposed. In longitudinal stretching, it is preferable to preheat the film temperature to 65 to 110 ° C. with a preheating roll. When the film temperature is lower than 65 ° C., the film tends to be difficult to be stretched (that is, it is likely to be broken) when stretched in the longitudinal direction. On the other hand, if the temperature is higher than 110 ° C., the film is likely to adhere to the roll, and there is a possibility that the occurrence of roll contamination due to continuous production may occur early.

When the film temperature reaches the above range, longitudinal stretching is performed. Longitudinal stretching is performed by the difference in speed of rolls. The longitudinal stretching ratio in biaxial stretching is not particularly limited as long as the area ratio is controlled to be 3 times or less, but it is preferably about 1.1 to 2.8 times.
It is preferable to once cool a film after longitudinal stretching, and it is preferable to cool with a cooling roll whose surface temperature is 20-40 degreeC.

2.2 (d) Heat treatment Next, the film after transverse and longitudinal stretching is introduced into a second tenter to perform final heat treatment. The final heat treatment is a preferred embodiment because it can adjust the shrinkage factor in the stretched direction. The heat treatment temperature is preferably 65 to 250 ° C. When the heat treatment temperature is lower than 65 ° C., the shrinkage factor of the film does not change and remains high. The heat treatment temperature is preferably as high as possible because the shrinkage rate of the film can be reduced. However, when the heat treatment temperature exceeds 250 ° C., the film is crystallized and the heat seal energy is unfavorably lowered.
In addition, during the final heat treatment, it is also possible to reduce the clip interval in the lateral direction at an arbitrary magnification (relaxation treatment). Similar to the above-mentioned final heat treatment, the relaxation treatment is also a preferred embodiment because it can adjust the contraction rate in the stretched direction. The relaxation rate is preferably 0.1 to 20%.
In addition, although the example of transverse stretch-longitudinal stretch is demonstrated here, in the case of longitudinal stretch-transverse stretch which reverses order, the film after longitudinal stretch and transverse stretch is finally heat-treated. The heat treatment may be carried out in the same tenter immediately after stretching, if it is carried out after the transverse stretching.

  Finally, the polyester film roll is obtained by winding the film while cutting and removing both ends of the film.

3. Bag-in-box inner bag Generally, a bag-in-box inner bag is roughly divided into an inner layer for storing and protecting contents and an outer layer that resists external impact and the like. The bag-in-box inner bag of the present invention has the polyester-based sealant of the above 1 in the innermost layer. The polyester-based sealant may be subjected to coating treatment, flame treatment, etc. in order to improve the adhesion of the film surface, and the polyester-based sealant thus surface-treated is also optional without departing from the function of the present invention. Can be provided.

3.1 Layers Other than Polyester-Based Sealant The inner bag for bag-in-box of the present invention has, for example, the outer side of the polyester-based sealant for the purpose of improving the tensile strength, impact strength, flex resistance and the like of the bag. It is preferable to provide the layers described and to stack them. The following layers may have one or more layers.

  The kind of film used for layers other than a polyester type | system | group sealant is not specifically limited, Arbitrary films, such as a polyamide type, polyester type, polyolefin type, etc. are mentioned. Among these, in order to improve the strength of the bag-in-box, it is preferable to use a polyester film and a polyamide film, and it is more preferable to use one or more layers of a polyamide film which is further excellent in strength and the like. It is very useful to provide a polyamide-based film, particularly in the outer layer where impact strength and the like are required. Moreover, in order to join the inner layer and outer layer of a bag by adhesion | attachment means, such as a heat seal, use of an olefin type film is preferable.

  Here, as a raw material of the polyamide-based film, for example, polycapramide (nylon 6), polyhexamethylene adipamide (nylon 66), caprolactam / lauryl lactam copolymer (nylon 6/12), caprolactam / hexamethylene diammonium Adipate copolymer (nylon 6/66), ethylene ammonium adipate / hexamethylene diammonium adipate / hexamethylene diammonium sebacate copolymer (nylon 6/66/610), polymer of metaxylylene diamine and adipic acid ( MXD-6), 1 type of resin chosen from hexamethylene isophthalamide / terephthalamide copolymer (amorphous nylon), or mixed resin etc. which mixed 2 or more types of these, etc. are mentioned. In addition, an adhesion modifying layer can be provided on the surface of the film made of the above-described resin. The material of the adhesion modifying layer may, for example, be an acrylic resin, a water-soluble or water-dispersible polyester resin, or a hydrophobic polyester resin obtained by graft copolymerizing an acrylic resin.

  Moreover, as a raw material of a polyester-type film, in addition to the polyester raw material as described in said 2.1, a polyethylene terephthalate can be used preferably.

  Moreover, as a raw material of a polyolefin film, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), an ethylene alpha olefin copolymer etc. are mentioned, for example. Ethylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1 etc. can be used as an alpha-olefin monomer at the time of obtaining an ethylene alpha olefin copolymer.

  The polyamide-based film and the polyolefin-based film described above can be produced by extruding these raw materials by a T-die method or an inflation method, and using any method of non-stretching, uniaxial stretching, and biaxial stretching.

  A polyester film can produce these raw materials according to the film forming conditions described in the above 2.2.

3.2 Stacking Configuration of Bag-In-Box Inner Bag A schematic cross-sectional view of a preferable embodiment of the bag-in-box inner bag of the present invention is shown in FIG. The bag-in-box inner bag shown in FIG. 3 is composed of an outer layer 1 resistant to external impact and the like, and an inner layer 2 protecting the contents. The outer layer 1 and the inner layer 2 and the inner layer 2 are adhered to each other by a heat seal portion 3. Although the number of layers may be two, that is, the outer layer 1 and the inner layer 2 as shown in FIG. 3, three or more intermediate layers other than the outer layer and the inner layer may be provided. However, if the total number is 3 or more, the weight of the film used for the inner bag will increase, so two layers are sufficient.

  FIG. 4 is an enlarged view of a cross section taken along the broken line 4 in FIG. The outer layer 1 is composed of 1a and 1b in order from the outside, and the inner layer 2 is composed of 2a, 2b and 2c in order from the outside. 2c is the innermost layer, and the innermost layers 2c are adhered to each other by the heat seal part 3. However, the laminated structure of the bag-in-box inner bag according to the present invention is not limited to FIG. 4. For example, the outer layer 1 may have two or more layers, and the inner layer 2 may have three or more layers.

  Here, it is preferable to use the polyamide-based film or the polyester-based film described in the above-mentioned 3.1 for the outermost layer 1a, in order to withstand stimulation such as external impact, rubbing, bending and the like. Use is more preferred. Moreover, it is preferable to use the film of the kind which can adhere | attach an outer layer and an inner layer to the outer layer 1b and the inner layer 2a. Although the kind of said film is not specifically limited, For example, it is preferable to use the polyolefin-type film as described in said 3.1.

  The inner layer 2b is provided to bond the inner layer 2a and the inner layer 2c, and is preferably an adhesive resin layer formed by extrusion lamination or dry lamination. In the case of extrusion lamination, it is preferable to use a polyolefin film as the resin of the inner layer 2b as in the case of the inner layer 2a. Of the inner layer 2, the innermost layer 2c in direct contact with the contents is made of the polyester-based sealant of the present invention. As a result, it is possible to prevent the deterioration of taste and flavor as well as the prevention of deterioration and adsorption of contents.

  Furthermore, in the bag-in-box inner bag of the present invention, it is preferable to provide a gas barrier layer when the content is required to have a gas permeation preventing function such as oxygen or water vapor. The gas barrier layer may be provided on any layer outside of the polyester-based sealant located in the innermost layer, but if it is provided on the outer layer 1, for example, it is provided on the outer layer 1a (outermost layer) and the inner layer 2 If it exists, it can be suitably provided in the further outer side etc. of the inner layer 2a. As the oxygen barrier layer or the water vapor barrier layer, for example, a deposited layer of metal or nonmetal such as ethylene vinyl alcohol, polyvinylidene fluoride, metaxylylene adipamide, aluminum, or a nanocomposite-containing layer can be suitably used. .

3.3 Laminating Method of Film In the inner bag for bag-in-box shown in FIG. 4, dry laminating and extrusion laminating are preferable as a method of bonding adjacent films such as the outer layers 1a and 1b and the inner layers 2a and 2b. .

  In the case of dry lamination, a commercially available dry lamination adhesive can be used. As a representative example, Dick Dry (registered trademark) LX-703VL manufactured by DIC, KR-90 manufactured by DIC, Takenate (registered trademark) A-4 manufactured by Mitsui Chemicals, Takerack (registered trademark) A-905 manufactured by Mitsui Chemicals Etc.

  In the case of extrusion lamination, polyethylene or the like is melted and adhered between layers or layers and other layers, but it is also preferable to laminate an anchor coat layer in order to enhance the adhesion of the surface of the layer etc. . Representative examples of resins used for extrusion lamination include Novatec (registered trademark) LC600A manufactured by Japan Polyethylene Corporation, Sumikasen (registered trademark) L405-H manufactured by Sumitomo Chemical Co., Ltd., Petrocene (registered trademark) 225 manufactured by Tosoh Corporation, and the like.

3.4 Method of producing bag-in-box inner bag In the bag-in-box inner bag shown in FIG. 4, it is preferable that the outer layer 1 and the inner layer 2 and the inner layer 2c be bonded by heat sealing. The heat sealing method is not particularly limited, and a conventional method such as heat sealing with a heat bar (or heat jaw) or impulse sealing can be used.

  The step of forming the inner bag for bag-in-box is not particularly limited, and the film may be formed according to a conventional method such as a four-way seal, a three-way seal, a pillow bag (glued paste), an envelope paste, and a gusset paste method. it can. The bag-in-box inner bag of the present invention can also be fitted with an openable / closable plug that pierces through the cardboard wall disposed outside in order to facilitate the filling and removal of the contents. The material of the plug may be metal or plastic, but in the bag-in-box of the present invention, it is preferable that the material of the plug is also polyester because it uses a polyester sealant for the innermost layer.

  EXAMPLES Next, the present invention will be specifically described using Examples and Comparative Examples, but the present invention is not limited to the aspect of the Examples in any way, and can be suitably modified without departing from the scope of the present invention. Is possible.

The evaluation method of the film is as follows.
<Evaluation method of polyester film>
Polyester film No. 1 described in Table 2 to be described later. The following characteristics were evaluated about 1-6.

[Heat seal energy, heat seal strength, heat seal elongation]
In accordance with JIS Z1707, the heat seal strength was measured when polyester-based films were sealed at 140 ° C. for 1 second.
Specifically, first, a sample cut out so as to have a seal width of 15 mm was prepared, and heat seal surfaces were adhered to each other with a heat sealer. The heat seal energy was measured at a tensile speed of 200 mm / min using a universal tensile tester “DSS-100” (manufactured by Shimadzu Corporation) to determine the heat seal strength. At this time, the integrated value of the heat seal elongation and the heat seal strength was calculated, and the energy per 15 mm (J / 15 mm) was shown.
Here, “heat seal strength” is the maximum value of the above heat seal curve, and “heat seal elongation” is between 5% (the start point and the end point) of the heat seal strength maximum value. It is a distance.

[Haze]
According to JIS-K-7136, it measured using a haze meter (made by Nippon Denshoku Industries Co., Ltd., 300A). The measurement was performed twice and the average value was calculated.

[Uneven thickness in the longitudinal direction]
A polyester film is sampled in a roll of 11 m in the longitudinal direction and 40 mm in the width direction, and continuously measured along the longitudinal direction of the film at a measurement speed of 5 m / min using a continuous contact thickness meter manufactured by Micron Measuring Instruments Co., Ltd. The thickness was measured (measurement length is 10 m). Assuming that the maximum thickness at the time of measurement is Tmax, the minimum thickness is Tmin, and the average thickness is Tave, thickness unevenness in the longitudinal direction of the film was calculated based on the following equation.
Thickness unevenness in the longitudinal direction = {(Tmax−Tmin) / Tave} × 100

[Uneven thickness in the width direction]
A polyester film is sampled in a wide band of 40 mm in length and 1.2 m in width, and is measured along the width direction of the film sample at a measurement speed of 5 m / min using a continuous contact thickness meter manufactured by Micron Measuring Instruments Co., Ltd. The thickness was measured continuously (measurement length is 1 m). Assuming that the maximum thickness at the time of measurement is Tmax, the minimum thickness is Tmin, and the average thickness is Tave, thickness unevenness in the width direction of the film is calculated based on the above equation.

<Evaluation method of inner bag for bag in box>
[Taste evaluation]
Using the laminated film described in Table 4 to be described later, the taste of the mineral water (product name "Irohasu", manufactured by Nippon Coca-Cola Co., Ltd.) was sensory-evaluated. The details of the evaluation method are as follows.

  First, the laminated film was cut into a square of 50 cm × 50 cm, the mass was measured, and three sides of the laminated film were heat sealed. 20 L of mineral water was put into the bag from one side which was not heat-sealed (the bag could be opened), and the last empty side was sealed by heat-sealing. The distance measured inside the seal line was 45 cm × 45 cm.

After storing a bag of mineral water for one week at a temperature of 5 ° C and a relative humidity of 30%, pour the mineral water from the bag into a glass cup and have it drink on a total of 16 people. The following criteria were used to determine The breakdown of the monitors was 4 in their 20's, 4 in their 30's, 4 in their 40's and 4 in their 50's, and the ratio of men and women was half and half in each age.
○: 0 to 1 number of people who felt a poly-odor out of 16 、: 2 to 5 people who felt a poly-odor on 16 people ×: 6 to 16 people who felt a poly-odor on 16 people

[Adsorption evaluation]
The adsorptivity of limonene (manufactured by Nacalai Tesque, Inc.) or menthol (manufactured by Nacalai Tesque, Inc.) was evaluated using the laminated film described in Table 4. The details of the evaluation method are as follows.

  First, the laminated film was cut into a square of 50 cm × 50 cm, the mass was measured, and three sides of the laminated film were heat sealed. 20 L of a diluted solution of limonene or menthol was put into the bag from one side which was not heat-sealed (the bag can be opened), and the last empty side was sealed by heat-sealing. The distance measured inside the seal line was 45 cm × 45 cm. In addition, limonene and menthol were prepared by adding ethanol so that the mass concentration would be 30%.

After storing the bag containing the contents for one week at room temperature, the contents were taken out and the inside of the bag was washed with pure water, and then dried in a room at a temperature of 23 ° C. and a relative humidity of 60% for 1 day. The mass of the bag before and after drying was measured, and the adsorption amount of limonene or menthol was calculated based on the following equation.
Adsorption amount = (weight of bag after drying)-(weight of bag before drying)

The amount of adsorption was determined based on the following criteria.
○: 0 mg or more and 100 mg or less Δ: more than 100 mg, 300 mg or less ×: more than 300 mg

[Dump bag evaluation]
Using the laminated film described in Table 4, tap water was placed therein to prepare a dropper sample.

  Specifically, a plurality of samples in which the laminated film was cut into a square of 50 cm × 50 cm were prepared, the mass was measured, and three sides of the laminated film were heat sealed. 20 L of tap water was put into the bag from one side which was not heat-sealed (the bag could be opened), and the last vacant side was sealed by heat-sealing. The distance measured inside the seal line was 45 cm × 45 cm.

Five sheets were randomly taken out of the prepared samples, and the bag dropping test was performed. First, one film surface of the sample was directed to the floor and dropped once from a height of 3.0 m, then the sample was collected, and the film surface on the opposite side was dropped to a floor again with a height of 3.0 m . The bag dropping test was performed twice for one sample. The number of times until the bag was broken was scored according to the following criteria, and the sum after 5 tests was calculated as the drop bag score (maximum 2 points × 5 times = 10 points full marks). A dropout score of 6 or more is regarded as pass (○), and 5 or less is regarded as rejection (x). In the above evaluation method, the height at the drop bag test is as high as 3.0 m, so it can be said that this evaluation test is more severe than the general drop bag test.
1st torn bag: 0 points 2nd torn bags: 1 point No torn bags: 2 points

<Synthesis of polyester raw material>
[Synthesis of Polyester Raw Material A]
100 mol% of dimethyl terephthalate (DMT) as a dicarboxylic acid component and 100 mol% of ethylene glycol (EG) as a polyhydric alcohol component in a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux condenser Charge ethylene glycol to be 2.2 times the molar ratio of dimethyl terephthalate, add 0.05 mol% (relative to acid component) of zinc acetate as transesterification catalyst, and remove methanol formed out of system Transesterification was carried out while leaving. Thereafter, 0.225 mol% (relative to the acid component) of antimony trioxide is added as a polycondensation catalyst, and a polycondensation reaction is performed under a reduced pressure condition of 26.7 Pa at 280 ° C., and the intrinsic viscosity is 0.75 dl / g Polyester raw material A was obtained. The polyester raw material A is polyethylene terephthalate. The composition of the monomer component of polyester raw material A is shown in Table 1. In Table 1, TPA is terephthalic acid, IPA is isophthalic acid, BD is 1,4-butanediol, NPG is neopentyl glycol, CHDM is 1,4-cyclohexanedimethanol, and DEG is diethylene glycol. In Table 1, in the column of "dicarboxylic acid component", the content of each monomer component in 100 mol% of all carboxylic acid components, in the column of "diol component", each monomer component in 100 mol% of all diol components Indicates the content of

[Synthesis of Polyester Raw Materials B to F]
Based on the procedure similar to the said polyester raw material A, polyester raw material BF from which a monomer component differs was obtained. The polyester raw material F was manufactured by adding SiO ₂ (Pyrcia 266 manufactured by Fuji Silysia) as a lubricant at a ratio of 7,000 ppm with respect to the polyester. Each polyester was suitably chipped. The compositions of these monomer components are shown in Table 1. The intrinsic viscosity of each polyester raw material was B: 0.78 dl / g, C: 0.73 dl / g, D: 0.73 dl / g, E: 0.80 dl / g, F: 0.75 dl / g .

  Using the above polyester raw materials A to F, polyester film No. 1 described in Table 2 was used. 1 to 6 was formed.

(Film formation of polyester film No. 1)
As shown in Table 2, polyester raw material A, polyester raw material B, polyester raw material D, polyester raw material E, and polyester raw material F are mixed at a mass ratio of 79: 10: 3: 3: 5 and introduced into a twin screw extruder. After extruding from a T-die melted at 270 ° C., a non-stretched single-layer polyester film No. 1 was extruded by cooling on a chill roll set to a surface temperature of 30 ° C. I got one.

(Film formation of polyester film No. 2)
Polyester film No. A non-stretched single layer film was obtained in the same manner using the same raw material as in 1.
Next, the unstretched single-layer film is introduced into a tenter and transversely stretched at 82 ° C. and 1.5 times in the transverse stretching zone, and then introduced into the final heat treatment zone of the same tenter, for 8 seconds at a temperature of 83 ° C. While heat treatment is carried out, the width of the clip of the tenter is reduced and relaxation is carried out by 5% to obtain a laterally uniaxially stretched polyester film No. 1 I got two.

(Film formation of polyester film No. 3 and 4)
The above-mentioned polyester film No. No. 1 above except that the blending ratio of the polyester raw materials was changed as shown in Table 2. Non-stretched single-layer polyester film No. 1 I got three and four.

(Film formation of polyester film No. 5)
The above-mentioned polyester film No. In the same manner as in 4, a non-stretched single layer film was obtained.
Next, the unstretched single layer film is led to the first tenter and transversely stretched at 82 ° C., 3.8 times in the transverse stretching zone, and then the transversely stretched film is taken as a group of rolls including low speed and high speed rolls. It was led to a longitudinally arranged longitudinal stretcher, preheated on a preheating roll until the film temperature reached 70 ° C., and then longitudinally stretched so that the draw ratio would be 2.8 times on a low speed, high speed roll. Thereafter, the longitudinally stretched film was forcibly cooled by a cooling roll set to a surface temperature of 25 ° C.
Then, the cooled film is guided to a second tenter, heat-treated in a second tenter at 93 ° C. for 10 seconds, and relaxed in 17% transverse direction (film width direction), and then cooled, both edges By cutting and removing the part, a polyester film 5 having a thickness of about 30 μm was obtained. The above No. The area ratio of transverse stretching and longitudinal stretching at 5 is 10.6 times (倍 3.8 times × 2.8 times).

(Film formation of polyester film No. 6)
The above-mentioned polyester film No. No. 5, except that the blending ratio of polyester raw materials, transverse stretching, longitudinal stretching, and final heat treatment conditions were changed as shown in Table 2. In the same manner as in 5, a polyester film 6 was formed. The above No. The area magnifications of the transverse stretching and the longitudinal stretching in No. 6 are the same as in the above-mentioned No. Similar to 5, it is 10.6 times.

  The polyester film No. 1 obtained in this manner. The characteristics of 1 to 6 were measured by the method described above. The results are shown in Table 2. For the sake of reference, FIGS. The result of the heat seal curve obtained in 1, 5 is shown, respectively.

(Preparation of laminated film)
The above polyester-based film was used as the innermost layer, and the film described in Table 3 was laminated on the outer side to produce a bag-in-box inner bag described in Table 4.
The details of the films described in Table 3 are as follows.
・ NY: biaxially stretched polyamide film (Toyobo Co., Ltd. Toyobo Harden (registered trademark) film NAP 02, thickness 15 μm)
VMNY: A film obtained by providing a barrier film on the above-mentioned NY film (Ecosial (registered trademark) film VN130, 15 μm thick, manufactured by Toyobo Co., Ltd.)
LLDPE (1): Low density linear polyethylene film (Toyobo Co., Ltd. Toyobo Lix (registered trademark) film L4103; thickness 30 μm, 50 μm, 60 μm)
LLDPE (2): Low density linear polyethylene film (Toyobo Co., Ltd. Toyobo Lix (registered trademark) film L4182, thickness 80 μm)

Example 1
Polyester film No. 1 described in Table 2 1 roll out, No. 1 in Table 3 on one side. A film of 4 (50 μm) was adhered by extrusion lamination. The adhesive resin is adhered to a thickness of 20 μm using a polyethylene resin for extrusion lamination (Novatec (registered trademark) LC600A made by Japan Polyethylene), and polyester film No. 1 is sequentially laminated from the innermost layer side. An inner layer film consisting of three layers of 1 (20 μm) / adhesive resin (PE) (20 μm) / low density linear polyethylene film (LLDPE, 50 μm) was produced.

  Aside from the inner layer film described above, No. 1 in Table 3 No. 1 film (15 μm) and No. 1 in Table 3 Biaxially stretched polyamide film (NY, 15 μm) / low density linear polyethylene by laminating the film No. 5 (60 μm) with an adhesive for dry lamination (Takelac (registered trademark) A-950 manufactured by Mitsui Chemicals, Inc.) An outer layer film consisting of two layers of film (LLDPE, 60 μm) was produced.

  Next, low density linear polyethylene films of the outer layer film and the inner layer film described above are superimposed (outer layer: biaxially stretched polyamide film (NY, 15 μm) / low density linear polyethylene film (LLDPE, 60 μm) / Inner layer: Two low density linear polyethylene films (LLDPE, 50 μm) / adhesive resin (PE, 20 μm) / polyester film No. 1 (30 μm) were prepared. 1) It piled up so that each other might become the innermost layer. The one-side lamination thickness at this time was 165 μm.

  The laminated film laminated as described above was cut into a square of 50 cm × 50 cm, and four sides of the laminated film were heat-sealed to produce an inner bag for bag-in-box of Example 1. At this time, the distance measured inside the seal line was 45 cm × 45 cm.

[Examples 2 and 3]
The bag-in-box inner bags of Examples 2 and 3 were produced in the same manner as in Example 1 except that the types of films used for the inner layer and the outer layer in Example 1 were changed as shown in Table 4A. .

Example 4
Polyester film No. 1 described in Table 2 Roll out No. 4 and use No. 4 of Table 3 on one side using an adhesive for dry lamination (Takelac (registered trademark) A-950 manufactured by Mitsui Chemicals, Inc.). The film (50 μm) of No. 4 was adhered, and polyester film No. 1 was sequentially attached from the innermost layer side. An inner layer film consisting of two layers of 4 (30 μm) / low density linear polyethylene film (LLDPE, 50 μm) was prepared.

  Aside from the above inner layer film, an outer layer film composed of two layers of biaxially stretched polyamide film (NY, 15 μm) / low density linear polyethylene film (LLDPE, 60 μm) was produced in the same manner as in Example 1 above.

  Next, low density linear polyethylene films of the outer layer film and the inner layer film described above are superimposed (outer layer: biaxially stretched polyamide film (NY, 15 μm) / low density linear polyethylene film (LLDPE, 60 μm) / Inner layer: Two low density linear polyethylene films (LLDPE, 50 μm) / polyester film No. 3 (60 μm) are prepared. 4 was piled up so as to be the innermost layer. The one-side lamination thickness at this time was 155 μm.

  The above laminated film was cut into a square of 50 cm × 50 cm, and four sides of the laminated film were heat sealed. At this time, the distance measured inside the seal line was 45 cm × 45 cm, and the remaining laminated film outside the seal line was cut off leaving 1 cm from the outside of the seal line.

[Examples 5, 6]
The bag-in-box inner bags of Examples 5 and 6 were produced in the same manner as in Example 1 except that the types of films used for the inner layer and the outer layer in Example 4 were changed as shown in Table 4A. .

Comparative Examples 1 to 3
The bag-in-box inner bags of Comparative Examples 1 and 2 were produced in the same manner as in Example 1 except that the types of films used for the inner layer and the outer layer in Example 1 were changed as shown in Table 4B. . Also in Comparative Example 3, an attempt was made to manufacture an inner bag for a bag-in-box in the same procedure, but no bag could be manufactured. Specifically, in Comparative Example 3, polyester-based film No. 1 in Table 2 in which the heat seal energy is zero in the innermost layer. Since No. 6 was used, the innermost layers could not be bonded by heat sealing.

  The characteristics of each bag-in-box inner bag obtained in this manner are shown in Tables 4A and 4B.

[Evaluation result of film]
The bags of Examples 1 to 6 are excellent in various properties as shown in Table 4A, and are suitably used as an inner bag for bag-in-box.

On the other hand, in Comparative Example 1, as the innermost layer, polyester-based film No. 1 in Table 2 in Table 2 having the largest heat seal strength but low heat seal energy and heat seal elongation. Since 5 was used, dropout evaluation was 3 and lower compared with the said Example, and the use as a bag-in-box inner bag was unsuitable.
Moreover, although the bag of the comparative example 2 is excellent in drop-bag evaluation, No. 1 of Table 3 to an innermost layer. Since the low density linear polyethylene film of 4 was used, taste evaluation and adsorption evaluation of limonene and menthol were lowered.

Claims (9)

  A polyester-based sealant is provided in the innermost layer, and the heat sealing energy when the polyester-based sealants are sealed at 140 ° C. and one second is 0.10 J / 15 mm to 0.5 J / 15 mm. Inner bag for bag-in-box.   The inner bag for a bag-in-box according to claim 1, wherein the heat seal strength when the polyester sealants are sealed at 140 ° C for 1 second is 5 N / 15 mm or more and 30 N / 15 mm or less.   The inner bag for a bag-in-box according to claim 1 or 2, wherein the heat seal elongation is 10 mm or more and 30 mm or less when the polyester-based sealants are sealed at 140 ° C for 1 second.   The polyester component according to any one of claims 1 to 3, which contains at least one selected from the group consisting of neopentyl glycol, 1,4-cyclohexanedimethanol, isophthalic acid, and diethylene glycol as a polyester component constituting the polyester-based sealant. Bag for bag-in-box.   The bag-in-box inner bag according to any one of claims 1 to 4, wherein the polyester component of the polyester-based sealant further comprises 1,4-butanediol.   The thickness of the said polyester type sealant is 9 micrometers or more and 120 micrometers or less, The inner bag for bag in boxes in any one of Claims 1-5.   The bag-in-box inner bag according to any one of claims 1 to 6, wherein at least one layer of a polyamide-based film is laminated on the outside of the polyester-based sealant.   The bag-in-box inner bag according to any one of claims 1 to 7, wherein a gas barrier film is provided on the outside of the polyester-based sealant.   A polyester film for the innermost layer of a bag-in-box inner bag, which has a heat seal energy of 0.10 J / 15 mm or more and 0.5 J / 15 mm or less when polyester-based sealants are sealed at 140 ° C. for 1 second.

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