JP6727956B2 - Packaging films and bags - Google Patents

Description

The present invention relates to a packaging film and a packaging bag that can suppress the diffusion of odors.

When an object is wrapped with a polyethylene film, the aroma retaining property of the film itself is not sufficient, and when the object wrapped with the film has a strong odor, the odor leaks through the film. On the other hand, the polyester film has a fragrance-retaining property, and odor does not easily pass through the film.

For example, Patent Document 1 discloses a polyethylene terephthalate film having a reduced film density. An object can be placed in the center of the film, the film can be wrapped around the film, and the film can be kept twisted for a certain period of time after being twisted (hereinafter referred to as twist holding property).

However, the polyester film of Patent Document 1 has room for improvement in heat resistance and durability against impact from the outside (impact resistance), and if a bag produced using this film is repeatedly used, it will be part of the bag. There are problems such as tearing.

In order to make up for such a drawback of the polyester film, for example, Patent Document 2 discloses a laminated film in which a polyamide film is attached to at least one surface of the polyester film. The laminated film of Patent Document 2 has an advantage that heat resistance and impact resistance can be enhanced as compared with the case of using a polyester film alone.

However, in the case of the laminated film of Patent Document 2, the impact resistance and the heat resistance can be improved, but there is a problem that the twist holding property is deteriorated.

Further, although the impact resistance of the laminated film can be increased by increasing the thickness of the polyester film or the polyamide film, there is a problem that the twist holding property is deteriorated.

Japanese Patent No. 4308662 Japanese Patent No. 5256754

The present invention is a package in which an object is placed at the center of a film, the film is wrapped around the film, the film is twisted, and the twisted state is maintained even after standing for a certain period of time, and the fragrance and impact resistance are excellent. The issue is to provide a film for use.

The first packaging film of the present invention is a packaging film containing a first layer made of a resin composition and a second layer made of the same or different material as the first layer, wherein the packaging film is The first layer and the second layer are bonded to each other, and the twist holding angle is 270 degrees or more.

In the first packaging film of the present invention, the second layer is preferably made of a material different from that of the first layer, and the first layer preferably contains a polyester resin.

The second packaging film of the present invention includes a first layer made of a resin composition, a second layer made of a material different from the first layer, and a third layer made of a material different from the second layer. A packaging film, the second layer is located between the first layer and the third layer, the packaging film, the first layer and the second layer are adhered to each other, It is characterized in that the two layers and the third layer are adhered, and the twist holding angle is 270 degrees or more.

In the second packaging film of the present invention, the first layer and the third layer preferably contain a polyester resin, and the first layer and the third layer are preferably made of the same resin composition.

In any packaging film, the impact strength is preferably 0.5 to 3.0 J, the second layer preferably contains a nylon resin or a polypropylene resin, the first layer, A polyester resin containing an ethylene terephthalate unit and an amorphous unit is preferably contained, and the thickness of the packaging film is preferably 10 to 100 μm.

The present invention also includes a packaging bag obtained by heat-sealing the packaging film.

The packaging film of the present invention has a twist holding angle of 270 degrees or more as measured by the twist holding evaluation method described below, and has sufficient twist holding property. In addition, the packaging film of the present invention is excellent in aroma retaining property and impact resistance of the film itself. Therefore, even when a strong odor object is packaged with the film of the present invention, the odor does not leak, and it is useful as a packaging film having excellent durability against external impact. In addition, since the packaging film of the present invention has a heat-sealing property, when the object to be wrapped with the film is relatively large, the film itself can be heat-sealed to be used as a bag.

It is a figure showing the measuring method of the folding holding angle of a film.

The packaging film according to the present invention is a laminated film in which a sheet-shaped second layer is laminated on the first layer, and nothing is laminated on the second layer (the surface on which the first layer is not laminated). In some cases, the third layer may be further laminated on the second layer (the surface on which the first layer is not laminated). Hereinafter, the packaging film may be referred to as a laminated film.

(First layer)
The first layer of the present invention is composed of a resin composition, and the resin composition forming the first layer (hereinafter, also referred to as a first film) preferably contains a polyester resin. The polyester resin preferably contains ethylene terephthalate unit as a main constituent component. The term "mainly" means that the content of the ethylene terephthalate unit is more than 50 mol% based on 100 mol% of all constituent units of the polyester. The ethylene terephthalate unit content is more preferably 55 mol% or more, still more preferably 60 mol% or more. In addition, in the present specification, the “unit” is a repeating unit constituting a polymer derived from one polyhydric alcohol molecule and one polycarboxylic acid molecule, and in the case of ε-caprolactone, The structural unit obtained by opening the lactone ring is shown.

The polyester resin preferably contains a unit derived from a polyhydric alcohol other than ethylene glycol and/or a unit derived from a polyvalent carboxylic acid other than terephthalic acid.

Examples of polyhydric alcohols other than ethylene glycol include propylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2- Aliphatic diols such as methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9-nonanediol and 1,10-decanediol; 1,4-cyclohexanedimethanol. A cycloaliphatic diol such as 4-cyclohexanediethanol; an aliphatic polyhydric alcohol such as trimethylolpropane and pentaerythritol;

Examples of polycarboxylic acids other than terephthalic acid include isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, 5-sodium sulfoisophthalic acid, 4,4'-diphenyldicarboxylic acid and diphenyl. Aromatic dicarboxylic acids such as sulfodicarboxylic acids; glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, succinic acid, etc., and aliphatic dicarboxylic acids usually called dimer acids; trimellitic acid, pyromellitic acid and Aromatic polycarboxylic acids such as acid anhydrides thereof; and the like.

From the viewpoint of improving the twist holding property, in the resin composition forming the first layer, it is preferable that the polyester unit contains an amorphous unit (the crystallinity of the first layer is not 100%), More preferably, the first layer contains a polyester resin containing an ethylene terephthalate unit and an amorphous unit. Specifically, the total amount of units derived from polyhydric alcohols other than ethylene glycol and units derived from polyvalent carboxylic acids other than terephthalic acid is preferably 10 mol% or more in 100 mol% of all the constituent units. , 13 mol% or more is more preferable.

A unit derived from a polyhydric alcohol other than ethylene glycol and/or a unit derived from a polyhydric carboxylic acid other than terephthalic acid can be an amorphous component. For that purpose, it is preferable to use diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol as the polyhydric alcohol, and it is preferable to use neopentyl glycol and/or 1,4-cyclohexanedimethanol. Isophthalic acid is preferably used as the carboxylic acid. Examples of the amorphous unit include a monomer unit composed of isophthalic acid and ethylene glycol, a monomer unit composed of terephthalic acid and neopentyl glycol, a monomer unit composed of terephthalic acid and 1,4-cyclohexanedimethanol, and isophthalic acid and butane. Examples thereof include a monomer unit composed of a diol.

The total amount of units derived from polyhydric alcohols other than ethylene glycol and units derived from polyvalent carboxylic acids other than terephthalic acid is preferably 30 mol% or less, and 27 mol% or less, in 100 mol% of all the constituent units. Is more preferable. If the total amount of units derived from polyhydric alcohol other than ethylene glycol and units derived from polyvalent carboxylic acid other than terephthalic acid exceeds 30 mol %, the resulting film may have insufficient impact resistance, or the film may have insufficient impact resistance. The tear resistance may be reduced.

Here, the interpretation of the above-mentioned "may be an amorphous component" will be described in detail.

In the present specification, the “amorphous polymer” composed of an amorphous unit specifically refers to a polymer having no endothermic peak due to melting as measured by a DSC differential scanning calorimeter. An amorphous polymer is a polymer in which crystallization has not substantially progressed and cannot be in a crystalline state, or a polymer having an extremely low crystallinity even when crystallized.

Further, in the present specification, the “crystalline polymer” refers to a polymer that is not the above “amorphous polymer”, that is, a polymer having an endothermic peak due to melting as measured by a DSC differential scanning calorimeter. A crystalline polymer is a polymer having crystallizable properties that can be crystallized upon heating, or a polymer that has already crystallized.

Generally, for polymers in which a large number of monomer units are bonded, the stereoregularity of the polymer is low, the symmetry of the polymer is poor, the side chains of the polymer are large, the branching of the polymer is large, the intermolecular between the polymers When it has various conditions such as a low cohesive force, it becomes an amorphous polymer. However, depending on the presence state of a polymer in which a large number of monomer units are bonded, crystallization of the polymer may proceed sufficiently to give a crystalline polymer. For example, even if the polymer has a large side chain, when the polymer is composed of a single monomer unit, the crystallization of the polymer may be sufficiently advanced to be crystalline. Therefore, even if a polymer is produced by using the same monomer unit, it may be a crystalline polymer or an amorphous polymer in some cases, and therefore, the expression “can be an amorphous component” in the present invention. Is used.

In the resin composition forming the first layer of the present invention, if necessary, various additives such as waxes, antioxidants, antistatic agents, crystal nucleating agents, viscosity reducing agents, and heat stabilizers. , A coloring pigment, an anti-coloring agent, an ultraviolet absorber and the like can be added. Further, it is preferable to add fine particles as a lubricant for improving the workability (sliding property) of the film. As the fine particles, any one can be selected, for example, as the inorganic fine particles, silica, alumina, titanium dioxide, calcium carbonate, kaolin, barium sulfate, etc., and as the organic fine particles, for example, acrylic resin. Examples thereof include particles, melamine resin particles, silicone resin particles and crosslinked polystyrene particles. The average particle size of the fine particles is within the range of 0.05 to 3.0 μm (when measured with a Coulter counter) and can be appropriately selected as necessary.

As a method of blending the particles in the resin composition forming the first layer, for example, the particles can be added at any stage of producing a polyester resin, but the esterification stage or the end of the transesterification reaction After that, it is preferable to add it as a slurry dispersed in ethylene glycol or the like at the stage before the start of the polycondensation reaction to proceed the polycondensation reaction. Further, a method of blending a slurry of particles dispersed in ethylene glycol or water with a polyester resin raw material using a kneading extruder with a vent, or using a kneading extruder, dried particles and a polyester resin raw material It is also preferable to carry out by a method of blending with.

Further, the first film may be subjected to corona treatment, coating treatment, flame treatment or the like in order to improve the adhesiveness of the film surface.

Next, the physical properties of the first film of the present invention will be described.

The twist holding angle of the first film is preferably 270 degrees or more, more preferably 300 degrees or more, and further preferably 360 degrees or more. When the twist holding angle of the first film is less than 270 degrees, when a strong odor object is wrapped with the laminated film, the odor may leak from the twist portion. The method for measuring the twist holding angle will be described later.

The first film preferably has a folding holding angle (hereinafter, simply referred to as a folding holding angle) of 20 degrees or more and 75 degrees or less, and more preferably 45 degrees or less, after being stored for 1 day in an environment of 20°C. It is more preferably 40 degrees or less, and most preferably 35 degrees or less. When the folding holding angle of the first film is 75 degrees or less, even when the laminated film is folded, it can be held in the folded state. Therefore, by folding the film, it is possible to suppress the odor from leaking from the folding mouth. it can. Further, by twisting and folding the laminated film, it is possible to more reliably suppress the leakage of odor. In addition, the smaller the folding holding angle of the first film, the smaller the folding holding angle of the laminated film. Therefore, the smaller the folding holding angle of the first film is, the more preferable it is. It doesn't matter. The method for measuring the folding holding angle will be described later.

The thickness of the first film is preferably 3 μm or more and 200 μm or less. The thinner the first film is, the larger the twist holding angle is, but if it is thinner than 3 μm, the processing may be difficult. If the thickness of the first film is thicker than 200 μm, the twist retention of the laminated film may be deteriorated. The thickness of the first film is more preferably 5 μm or more and 100 μm or less, and further preferably 7 μm or more and 40 μm or less. Since the twist holding angle of the laminated film tends to decrease as the thickness of the first film decreases, the thickness is more preferably 35 μm or less, and further preferably 30 μm or less.

In the case of a transparent type film, the first film of the present invention preferably has a haze of 0.5% or more and 15% or less. When the haze exceeds 15%, the transparency is lowered, so that use in applications where transparency is required may be limited. On the other hand, when the haze value is less than 0.5%, scratches and the like are likely to be conspicuous and productivity may be reduced.

The haze is measured by the following measuring method. Haze (%) was measured using a haze meter (“NDH2000” manufactured by Nippon Denshoku Co., Ltd.) by a method according to JIS-K-7105 for three different places of the obtained first film, and an average value thereof was obtained. Is the haze value of the first film.

On the other hand, in applications such as disposal of used diapers and waste, there is a demand for a semitransparent or opaque film, and for example, a film having a white or pearly appearance or a frosted glass appearance may be used. In the case of such a film, the total light transmittance is preferably 40% or less, more preferably 30% or less. In order to improve the hiding power of the film, it is preferable to include fine voids inside the film. For example, a foaming material may be mixed and extruded, but a preferable method is to obtain a cavity by mixing a thermoplastic resin which is incompatible with polyester into polyester and stretching the mixture in at least one axial direction. .. The thermoplastic resin which is incompatible with the polyester used in the present invention is optional and is not particularly limited as long as it is incompatible with the polyester. Specific examples include polystyrene resins, polyolefin resins, polyacrylic resins, polycarbonate resins, polysulfone resins, and cellulose resins. In particular, a polystyrene resin or a polyolefin resin such as polymethylpentene or polypropylene is preferable from the viewpoint of forming voids.

Polystyrene-based resin refers to a thermoplastic resin containing a polystyrene structure as a basic constituent, homopolymers such as atactic polystyrene, syndiotactic polystyrene, isotactic polystyrene, and other components grafted or block copolymerized. It includes a modified resin such as a high impact polystyrene resin or a modified polyphenylene ether resin, or a mixture of a thermoplastic resin compatible with these polystyrene resins, such as polyphenylene ether.

The polymethylpentene-based resin is a polymer having a unit derived from 4-methylpentene-1 in an amount of 80 mol% or more, preferably 90 mol% or more, and as other components, ethylene, propylene, butene-1, Examples are units derived from 3-methylbutene-1 and the like. The melt flow rate of such polymethylpentene is preferably 200 g/10 minutes or less, more preferably 30 g/10 minutes or less. This is because when the melt flow rate exceeds 200 g/10 minutes, it becomes difficult to obtain the effect of reducing the specific gravity of the film.

The polypropylene resin as a thermoplastic resin that is incompatible with polyester includes homopolymers such as atactic polystyrene and syndiotactic polystyrene, as well as modified resins obtained by grafting or block copolymerizing other components.

The thermoplastic resin which is incompatible with the polyester is present in the form of being dispersed in the polyester in various shapes such as a spherical shape, an elliptic spherical shape, or a thread shape. As described above, various additives and the like can be added to the mixture of the polyester and the thermoplastic resin incompatible with the polyester, if necessary. Further, it is preferable to add fine particles as a lubricant for improving the workability (sliding property) of the film and fine particles as a hiding aid for reducing the total light transmittance (increasing the haze). Any particles can be selected as the particles, and examples thereof include the inorganic particles described above and the organic particles described above. The average particle size of the fine particles is within the range of 0.05 to 3.0 μm (when measured with a Coulter counter) and can be appropriately selected as necessary. The same method as described above can be adopted for the method of blending the above particles in the resin forming the polyester film.

In the case of a transparent type film, the first film of the present invention preferably has a density of 1.29 g/cm ³ or more and 1.33 g/cm ³ or less. When the density is more than 1.33 g/cm ³ , the film may have poor twist retention and thickness uniformity.

On the other hand, when the first film of the present invention is a semitransparent or opaque film having a cavity inside, the density is 0.95 g/cm ³ or more and 1.25 g/cm ³ or less. preferable. When the density is more than 1.25 g/cm ³ , the film may have poor twist holding property and uneven thickness. When the density is less than 0.95 g/cm ³ , the number of cavities increases and the strength of the film may decrease, which is not preferable.

The density is measured by the following measuring method. Using a density gradient tube containing a liquid (calcium nitrate aqueous solution) having a continuous density gradient in the tube, the sample was placed in the liquid for 24 hours, and then the density of the sample was changed from a stationary equilibrium position in the liquid. Measure by reading.

The first film of the present invention is obtained by melt-extruding the above-mentioned polyester raw material with an extruder to form an unstretched film, and uniaxially or biaxially stretching the unstretched film by the following predetermined method. You can The polyester can be obtained by polycondensing the above-mentioned suitable dicarboxylic acid component and polyhydric alcohol component by a known method. Further, two or more kinds of chip-shaped polyester can be mixed and used as a raw material for a film.

When the raw material resin is melt-extruded, it is preferable to dry the polyester raw material using a dryer such as a hopper dryer and a paddle dryer, or a vacuum dryer. After drying the polyester raw material in this way, it is melted at a temperature of 200 to 300° C. and extruded into a film using an extruder. For extrusion, any existing method such as a T-die method or a tubular method can be adopted.

Then, an unstretched film can be obtained by rapidly cooling the sheet-shaped molten resin after extrusion. As a method of rapidly cooling the molten resin, a method of obtaining a substantially unoriented resin sheet by casting the molten resin from a die onto a rotating drum and rapidly solidifying it can be suitably adopted. A preferred manufacturing method is as follows.

In order to achieve the object of the present invention, the main shrinkage direction of the first film of the present invention may be either the longitudinal (longitudinal) direction or the lateral (width) direction of the film, and may be the longitudinal and lateral balanced shrinkage type. In the following, a lateral stretching-longitudinal stretching method in which transverse stretching is first performed and then longitudinal stretching is performed will be described. However, longitudinal stretching-horizontal stretching in which the order is reversed may only change the main shrinkage direction. ..

First, stretching in the lateral direction is performed. Stretching in the transverse direction is preferably carried out at 65° C. to 85° C. for about 3.5 to 5 times in a state where the widthwise ends of the film are held by clips in the tenter (first tenter). Prior to the stretching in the transverse direction, preheating is preferably performed, and preheating may be performed until the film surface temperature reaches 70°C to 100°C.

After transverse stretching, the film is preferably passed through an intermediate zone in which no positive heating operation is performed. When there is a temperature difference between the transverse stretching zone of the first tenter and the intermediate heat treatment zone, the heat of the intermediate heat treatment zone (hot air itself or radiant heat) flows into the transverse stretching process, and the temperature of the transverse stretching zone is not stable, so the film quality is stable. Since it may not occur, it is preferable to carry out the intermediate heat treatment after passing the film after transverse stretching and before the intermediate heat treatment through the intermediate zone for a predetermined time. In this intermediate zone, when a strip-shaped piece of paper is hung down without passing through the film, the accompanying flow accompanying the running of the film, the transverse stretching zone and the middle part are formed so that the piece of paper hangs almost completely in the vertical direction. When the hot air from the heat treatment zone is shut off, a stable quality film is obtained. A transit time of about 1 to 5 seconds is sufficient for passing through the intermediate zone. If it is shorter than 1 second, the length of the intermediate zone becomes insufficient, and the heat blocking effect becomes insufficient. Further, it is preferable that the intermediate zone is long, but if it is too long, the equipment becomes large, so about 5 seconds is sufficient.

After passing through the intermediate zone, either intermediate heat treatment before longitudinal stretching or no intermediate heat treatment may be performed. However, if the temperature of the intermediate heat treatment after the transverse stretching is increased, the molecular orientation that contributes to the foldability is relaxed and crystallization proceeds, so the foldability becomes slightly worse. In addition, the uniformity of the thickness also deteriorates. From this viewpoint, the intermediate heat treatment is preferably performed at 140° C. or lower. The transit time through the intermediate heat treatment zone is preferably 20 seconds or less. It is preferable that the intermediate heat treatment zone is long, but about 20 seconds is sufficient. This gives a horizontally uniaxially stretched film.

In the present invention, longitudinal stretching may or may not be carried out subsequently, but it is preferable to carry out longitudinal stretching because the tensile fracture strength of the first film is improved. Therefore, it is advisable to introduce the laterally uniaxially stretched film into a longitudinal stretching machine in which a plurality of roll groups are continuously arranged. In longitudinal stretching, it is preferable to preheat by a preheating roll until the film temperature reaches 65°C to 110°C. When the film temperature is lower than 65° C., it becomes difficult to stretch in the longitudinal direction (that is, breakage easily occurs), which is not preferable. On the other hand, if the film temperature is higher than 110° C., the film is likely to stick to the roll, and the roll is liable to become dirty during continuous production, which is not preferable.

When the temperature of the first film falls within the above range, longitudinal stretching is performed. The longitudinal stretching ratio differs depending on whether the main shrinkage direction is the longitudinal direction or the transverse direction. From the viewpoint of improving the tensile breaking strength, when the main shrinkage direction is the longitudinal direction, the longitudinal stretching ratio is preferably 2 to 5 times. On the other hand, from the viewpoint of improving the tensile fracture strength, when the main shrinkage direction is the transverse direction, the longitudinal stretching ratio is preferably 1.2 to 1.8 times.

After the longitudinal stretching, it is preferable to cool the film once, and it is preferable to cool it with a cooling roll having a surface temperature of 20 to 40° C. before the final heat treatment. Rapid cooling after longitudinal stretching stabilizes the molecular orientation of the film and reduces the natural shrinkage rate of the film after it is made into a product, which is preferable.

Next, the film after longitudinal stretching and cooling is introduced into a second tenter for heat treatment (relaxation treatment), and heat treatment (relaxation treatment) is performed. The relaxation treatment is a step of slackening the film at a relaxation rate of 0% to 30% while holding both ends of the film in the width direction with clips. The relaxation rate can change the lateral contraction rate. When the relaxation rate is increased, the contraction rate in the longitudinal direction does not change so much, but the contraction rate in the lateral direction is decreased. The lower limit of the relaxation rate is 0%, and the upper limit thereof is 99%. However, if the relaxation rate is high, there is a demerit that the film product width is shortened, which is not preferable. Therefore, the upper limit of the relaxation rate is preferably about 30%.

It is preferable that the first film is subjected to heat treatment to reduce the heat shrinkage rate of the first film within a range in which the twist holding property is not extremely impaired. Specifically, the heat treatment (relaxation) temperature is preferably 65°C to 140°C. If the heat treatment temperature is lower than 65°C, the heat treatment does not make sense. On the other hand, when the heat treatment temperature is higher than 140° C., the film is crystallized, and in the case of a transparent type film, the density tends to increase to more than 1.33 g/cm ³ , and the twist holding property and the thickness uniformity are poor. It may become a film.

After that, the film is wound while cutting and removing both ends of the film to obtain a polyester film roll made of the first film.

(Second layer)
The second layer is preferably made of a material different from that of the first layer, but may be a layer made of a resin composition or a layer made of a material other than the resin composition. By using various sheet-like materials as the second layer by taking advantage of the good twist-holding property of the first layer, a laminated film having excellent twist-holding property can be provided.

Examples of the layer made of a material other than the resin composition include aluminum foil and gold foil. By including aluminum foil or gold foil as the second layer, it is possible to easily provide a silver or gold packaging film. When an aluminum foil is used as the second layer, the second layer may have better twist retention than the first layer, and the heat shrinkage rate is small, which is a particularly preferred embodiment. Further, although the transparency of the laminated film is lowered, it is also possible to use paper as the second layer. Furthermore, even when the first layer and the second layer are made of the same resin composition, if a usage method in which the first layer and the second layer are not brought close to a hot object can be observed, a very preferable laminated film in terms of twist holding property. Is obtained. For example, the ink may be sandwiched between the first layer and the second layer made of the same resin composition as the first layer (the ink layer may be provided between the first layer and the second layer). Thus, it is possible to provide a packaging film having extremely excellent twist retention.

Next, a case where the second layer is made of a material different from that of the first layer will be described. Examples of the resin contained in the second layer include nylon resin, polypropylene resin, polyethylene resin, polystyrene resin, and the like, and nylon resin and polypropylene resin are preferable. As the resin contained in the second layer, only one kind may be used, or two or more kinds may be appropriately mixed and used. Further, although the transparency of the laminated film is lowered, it is possible to use paper as the second layer instead of the resin film.

Even if the second layer is made of the same resin composition as the first layer, even if it is made of a resin composition different from the first layer, aluminum foil, gold foil, paper, etc. which is not a resin layer Even in such a case, the twist holding angle of the second layer is preferably 270 degrees or more, more preferably 300 degrees or more, further preferably 330 degrees or more, and particularly preferably 360 degrees or more. If the twist holding angle of the second layer is less than 270 degrees, when a strong odor object is wrapped with the laminated film, the odor may leak from the twist portion.

In order to improve the twist holding property of the laminated film, it is preferable that the twist holding angle is as large as possible in the second layer as well, but it is also possible to use a second layer having a twist holding angle of less than 270 degrees. is there. The second layer is also not particularly limited to a transparent film, and a translucent film or an opaque film, a pearly gloss film, a frosted glass-like film, a colored film such as white, etc. can be selected depending on the application as desired. It is possible.

The thickness of the second layer is preferably 3 μm or more and 200 μm or less. If the thickness of the second layer is less than 3 μm, processing such as printing may be difficult. Further, the thickness of the second layer may be thicker than 200 μm, but since the used mass of the second layer increases, the cost increases. The thickness of the second layer is more preferably 7 μm or more and 100 μm or less, further preferably 10 μm or more and 70 μm or less.

A commercially available product may be used as the second layer, and examples of the commercially available product include Haden (registered trademark) films N1102, N1200 and N1202 manufactured by Toyobo Co., Ltd., Pyrene (registered trademark) films P2261 and P2161 manufactured by Toyobo Co., Ltd. And so on.

(Third layer)
The third layer of the present invention is preferably made of a resin composition, and the resin composition forming the third layer preferably contains a polyester resin. The preferred composition, physical properties, manufacturing method, and the like of the third layer of the present invention are the same as those described for the first layer, and therefore description thereof is omitted. Further, the third layer may be a layer made of the same resin composition as the first layer or a layer made of a different resin composition, but is preferably a layer made of the same resin composition as the first layer.

(Laminated film)
The laminated film according to the present invention has a structure including a first layer and a second layer made of the same material as or different from the first layer, or the first layer and the first layer made of a material different from the first layer. It includes two layers and a third layer made of a material different from that of the second layer, and the second layer is located between the first layer and the third layer. With such a configuration, the twist holding angle of the laminated film can be increased even when the twist holding angle of the second layer is small.

The thickness of the laminated film according to the present invention is preferably 10 to 100 μm, more preferably 20 to 80 μm.

The twist holding angle of the laminated film according to the present invention is 270 degrees or more, preferably 300 degrees or more, more preferably 330 degrees or more, and further preferably 360 degrees or more. When the twist holding angle of the laminated film is less than 270 degrees, when a highly odorous object is wrapped with the laminated film, the odor may leak from the twisted portion.

The folding retention angle of the laminated film according to the present invention is preferably 150 degrees or less, more preferably 120 degrees or less, further preferably 100 degrees or less, particularly preferably 90 degrees or less, and most preferably 70 degrees or less. .. When it exceeds 150 degrees, the folds are opened when the laminated film is folded, and a beautiful appearance cannot be obtained, which is not preferable. Further, the smaller the folding holding angle is, the more preferable, but the lower limit is currently about 30 degrees.

The laminated film according to the present invention preferably has an impact strength of 0.5 J or more, more preferably 0.6 J or more, still more preferably 0.8 J or more. When the impact strength is less than 0.5 J, if a bag produced by using this laminated film is repeatedly used, a part of the bag may be broken. Further, the higher the impact strength, the more preferable, but at present, the upper limit is about 3.0J. The method of measuring the impact strength will be described later.

The first layer, the second layer, and the third layer may be laminated in a plurality of layers, respectively, as long as the twist retention is not hindered, between the first layer and the second layer, and between the second layer and the third layer. Other layers may be provided between them. Examples of other layers include a first layer, a second layer, and a third layer, and it is also possible to laminate a plurality of first, second, and third layers. Further, the other layer may be a layer made of a material different from the first, second and third layers. Further, paper, aluminum foil, gold foil, an adhesive for dry lamination, an anchor coat layer for extrusion lamination, a polyethylene adhesive layer, etc. can be provided as other layers.

(Adhesion between adjacent layers)
When producing a laminated film according to the present invention, adjacent films are bonded to each other by dry lamination or extrusion lamination (for example, a first layer and a second layer are bonded, a second layer and a third layer are bonded together). (Bonding) is preferable. In the case of dry lamination, a commercially available adhesive for dry lamination can be used. As typical examples, DIC's Dick Dry (registered trademark) LX-703VL, DIC's KR-90, Mitsui Chemicals' Takenate (registered trademark) A-4, and Mitsui Chemicals' Takelac (registered trademark) A-905. And so on. In the case of extrusion lamination, polyethylene or the like is melted and adhered between layers or between a layer and another layer, but it is also preferable to laminate an anchor coat layer in order to enhance the adhesiveness of the surface of the layer or the like.

(Use)
The laminated film according to the present invention can be used for packaging a substance, and in particular, it can be used for packaging a strong odor substance such as a diaper after use, human sewage, vomiting substance, kimchi, and a comb. You can A strong odor substance can be placed in the center of the film, and the odor can be prevented from spreading to the surroundings simply by twisting the film so that the entire substance is wrapped in the film. Further, since the film of the present invention having twist holding property can be folded or knotted, it is possible to suppress the odor of a strongly odorous substance from diffusing to the surroundings by a method other than twisting the film. ..

Further, the strong odorous substance can be packaged by using a packaging bag obtained by heat-sealing the laminated film according to the present invention. In addition, it is also possible to make a diaper set in which a plurality of the above-mentioned packaging bags and a diaper are set.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples and is appropriately modified and implemented within a range compatible with the gist of the above and the following. It is also possible that they are all included in the technical scope of the present invention.

The methods for measuring the physical properties of the single layer film and the laminated films obtained in each of the examples and comparative examples are as follows.

(Twistability)
Cut the film into 30 cm x 30 cm squares, place the tennis ball with a diameter of 6.6 cm in the center of the film, with the first layer as the upper surface, lightly fix the toothpick on the twisted part with commercial cellophane tape before twisting, then the tennis ball And was twisted 1.5 times (540 degrees) clockwise (twist-wrapped). After left for 1 hour in an environment of 23° C. and 50% RH, the angle before the toothpick rotated clockwise was measured as a twist angle (twist holding angle).
The twist packaging was performed three times, the twist holding angle was measured, the average value thereof was calculated, and the following criteria were evaluated.
◯: Twist holding angle is 270° or more ×: Twist holding angle is less than 270°

(Aroma retention evaluation (odor control effect))
Using the laminated film, the inner layers of the film were heat-sealed (three-sided seal) so that the inner dimension of the bag was 50 mm×50 mm, and a bag having the first layer as the outer layer was produced. In the bag, absorbent cotton impregnated with 0.2 cc of each test flavor shown below was inserted and hermetically sealed. This bag was then placed in a 100 ml glass bottle, which was then covered and sealed. This glass bottle was allowed to stand at room temperature at 25° C., and evaluation was performed by the time until the smell started to be leaked. In the odor sensory test, the same panelists carried out sensory evaluations on the following three levels regarding presence or absence of perfume scent detection.
○: 2 weeks or more until the smell begins to leak △: 3 days or more and less than 2 weeks until the smell begins to leak ×: 3 days or less until the smell begins to leak As tofu, tomato juice, Salonpas (registered trademark), limonene, and Using menthol, the odor control effect was evaluated for each.

(Folding angle)
The film is left for 24 hours in a thermostatic chamber at 20° C. and 50% RH environment. Immediately thereafter, the film was cut into a 10 cm×10 cm square in a 20° C. 65% RH environment, lightly folded in four (a state in which 2.5 cm×2.5 cm squares were overlapped), and a load of 0.5 kg was applied with a test sealer. It took 1 second. Then, as shown in FIG. 1, the four corners of the sample 1 are in contact with the glass plate 2 or located in the vicinity of the glass plate 2 (where the fold vertices (the central portion of the sample 1 before folding in four) are separated from the glass plate 2). Sample 1 which is folded in four as shown in FIG. 2) is placed on the glass plate 2 and after 1 minute, the angle 3 at which the folded film is opened (completely folded state is 0 degree) is measured. The folding holding angle was calculated. The first layer was folded in four so that it was on the front side (mountain folding surface). Further, the folding holding angles in both the film longitudinal direction and the lateral direction were measured, and the larger value was used as the folding holding angle. In the measurement of the folding holding angle, in the case of a film sample in which the film longitudinal direction and the lateral direction are unclear, one direction is provisionally defined as the longitudinal direction, and the direction orthogonal to the temporary longitudinal direction is defined as the provisional lateral direction. .. Further, the folding holding angle of "x" indicates that the folding state could not be maintained after 1 second even though the folding was performed.

(Impact strength)
Using a film impact tester manufactured by Toyo Seiki Seisaku-sho, Ltd., the impact strength was measured under the environment of a temperature of 23° C. and a relative humidity of 65%.

(Polyester film No. 1 film formation)
Polyesters A to D are polyesters obtained by reacting the acid component and the polyhydric alcohol component shown in Table 1 below by a known method, and the lubricant contained in the polyester D is Fuji Silysia Syria ( Registered trademark) 266. Polyester film No. 1 using the above polyesters A to D. 1 was produced. The film forming method will be described below.

The above polyesters A to D were mixed in a mass ratio of 5:66:24:5 and charged into an extruder. Thereafter, the mixed resin was melted at 280° C., extruded from a T die, wound around a rotating metal roll cooled to a surface temperature of 30° C., and rapidly cooled to obtain an unstretched film having a thickness of 240 μm. At this time, the take-up speed of the unstretched film (the rotation speed of the metal roll) was about 20 m/min. After that, the unstretched film was led to a tenter (first tenter) in which a transverse stretching zone, an intermediate zone and an intermediate heat treatment zone were continuously provided. In the intermediate zone, when a strip-shaped paper piece is hung in a state where the film is not passed, so that the paper piece hangs almost completely in the vertical direction, hot air from the lateral stretching zone and the intermediate heat treatment zone Hot air is shut off.

Then, the unstretched film guided to the tenter is preheated until the film temperature reaches 80° C., then stretched 4 times in the transverse direction at 70° C. in the transverse direction, and after passing through the intermediate zone (passage) (Time=about 1.2 seconds), the film was introduced into an intermediate heat treatment zone and heat-treated at a temperature of 80° C. for 8 seconds to obtain a transversely uniaxially stretched film having a thickness of 60 μm.

Further, the laterally stretched film was introduced into a longitudinal stretching machine in which a plurality of roll groups were continuously arranged, preheated on a preheating roll until the film temperature reached 70° C., and then stretched 3 times. Then, 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 tenter (second tenter), heat-treated in an atmosphere of 90° C. for 10 seconds in the second tenter, and then cooled, and both edges are cut and removed. A biaxially stretched film of about 20 μm was continuously formed over a predetermined length to form a polyester film No. 1 (hereinafter referred to as film No. 1) was obtained. Film No. The folding holding angle, the twist holding angle, and the impact strength of No. 1 were measured, and the results are shown in Table 2.
Film No. The resin composition forming 1 is made of polyester resin. In addition, the film No. 1, the total amount of units derived from polyhydric alcohols other than ethylene glycol and units derived from polyvalent carboxylic acids other than terephthalic acid is 20 mol% in 100 mol% of all constituent units, and neopentyl glycol and diethylene glycol are included. Film No. 1 contains an amorphous component. In addition, the film No. The density of 1 is 1.32 g/cm ³ .

In addition to the above films, a Pyrene (registered trademark) film P2261 manufactured by Toyobo Co., Ltd. which is an OPP (biaxially oriented polypropylene) film, and a Harden (registered trademark) film N1200 manufactured by Toyobo Co., Ltd. which is an ONY (biaxially oriented polyamide) film are used. The folding holding angle, the twist holding angle, and the impact strength of each film were measured, and the results are summarized in Table 2.

(Example 1)
Film No. with a thickness of 20 μm 1 and a N1200 film having a thickness of 25 μm were laminated with an adhesive (Takelac (registered trademark) A-950 manufactured by Mitsui Chemicals, Inc.) to obtain a two-layer film. The folding holding angle, the twist holding angle, the impact strength, and the odor suppressing effect of the obtained two-layer film were measured, and the results are shown in Table 3.

(Example 2)
Film No. with a thickness of 20 μm 1 and a N1200 film having a thickness of 25 μm were laminated using an adhesive (Takelac (registered trademark) A-950 manufactured by Mitsui Chemicals, Inc.), and a film No. No. 1 having a thickness of 20 μm is formed on the surface on which No. 1 is laminated. 1 was bonded using an adhesive (Takelac (registered trademark) A-950 manufactured by Mitsui Chemicals, Inc.) to obtain a three-layer film. The folding holding angle, the twist holding angle, the impact strength, and the odor suppressing effect of the obtained three-layer film were measured, and the results are shown in Table 3.

(Example 3)
A three-layer film was obtained in the same manner as in Example 2 except that the N1200 film having a thickness of 25 μm was replaced with the P2261 film having a thickness of 20 μm. The folding holding angle, the twist holding angle, the impact strength, and the odor suppressing effect of the obtained three-layer film were measured, and the results are shown in Table 3.

(Comparative Example 1)
20 μm thick P2261 film and 20 μm thick film No. 1 and 1 were laminated using an adhesive (Takelac (registered trademark) A-950 manufactured by Mitsui Chemicals, Inc.), and the film No. A P2261 film having a thickness of 20 μm was adhered to the surface on which the P2261 film of No. 1 was not laminated with an adhesive (Takelac (registered trademark) A-950 manufactured by Mitsui Chemicals, Inc.) to obtain a three-layer film. .. The folding holding angle, the twist holding angle, the impact strength, and the odor suppressing effect of the obtained three-layer film were measured, and the results are shown in Table 3.

(Comparative example 2)
A three-layer film was obtained in the same manner as in Comparative Example 1 except that the P2261 film having a thickness of 20 μm was replaced with the N1200 film having a thickness of 25 μm. The folding holding angle, the twist holding angle, the impact strength, and the odor suppressing effect of the obtained three-layer film were measured, and the results are shown in Table 3.

The packaging film of the present invention has a twist holding angle measured by the above method of 270 degrees or more, and has sufficient twist holding property. Therefore, even when a strong odor object is packaged with the film of the present invention, the odor does not leak, and it is useful as a packaging film. The film of the present invention can be used for packaging a strong odor substance such as a diaper after use, filth of livestock, vomiting, kimchi, kusaya, etc. to suppress the diffusion of odor.

Claims (8)

A first layer comprising a resin composition and a packaging film comprising a second layer comprising the same or different material as the first layer,
The first layer contains a polyester resin,
The resin contained in the second layer is at least one selected from the group consisting of a polyamide resin and a polypropylene resin,
The packaging film is obtained by adhering the first layer and the second layer together, and has a twist holding angle of 270 degrees or more. Packaging film of the second layer according to claim 1 comprising a material different from the above first layer. A first layer comprising a resin composition, a second layer comprising a material different from the first layer, and a packaging film comprising a third layer comprising a material different from the second layer,
The first layer and the third layer contains a polyester resin,
The resin contained in the second layer is at least one selected from the group consisting of a polyamide resin and a polypropylene resin,
The second layer is located between the first layer and the third layer,
The packaging film is obtained by adhering the first layer and the second layer, and adhering the second layer and the third layer, and has a twist holding angle of 270 degrees or more. And packaging film. Packaging film according to claim 3 consisting of the same resin composition as the first layer and the third layer. The packaging film according to any one of claims 1 to 5 , wherein the packaging film has an impact strength of 0.5 to 3.0J. Above the first layer, the packaging film according to any one of claims 1 to 5, the polyester resin is contained comprising ethylene terephthalate units and amorphous units. Packaging film according to any one of claims 1 to 6 the thickness of the packaging film is 10 to 100 [mu] m. Packaging bag bag making by heat sealing the packaging film according to any one of claims 1-7.

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