Laminates, packaging bags, and methods for manufacturing the same thing.

Abstract

DEPCT66 What was offered was a laminate that excels in heat-sealing properties and... Suitable for reuse, the laminate includes: a first layer with a melting point of Tm1 and another layer with... Only type I polyethylene is the resin; and the second layer has a melting point of Tm2 and has... The only type II polyethylene is the resin, in which: the first and second layers are arranged respectively as... The outermost surface of the laminate; and Tm1-Tm2 greater than or equal to 24.0 degrees Celsius are conformed. -----------------------------------------------------------

Description

Laminate, packaging bag and method of manufacturing same

[0001] The present invention relates to a laminate, a packaging bag, and a method for producing the same.

[0002] In Japan, PET bottles and plastic containers and packaging are subject to recycling from the perspective of environmental conservation. PET bottles are easy to recycle because they usually contain only PET (polyethylene terephthalate) as a resin, and horizontal recycling has been established. On the other hand, plastic containers and packaging usually contain multiple types of resin, making separation difficult and resulting recycled products of low value.

[0003] One method for improving the value of recycled plastic containers and packaging is to use only a single resin as the resin that constitutes the plastic container and packaging (mono-materialization). In this method, since the plastic container and packaging contains only a single resin, separation of each resin is not required, and recycling can be easily carried out. Furthermore, since the obtained recycled products have high purity, recycled products with high value can be provided.

[0004] On the other hand, packaging bags for liquid refill pouches and the like are typically formed from a laminate comprising a polyethylene layer, which is an adhesive layer for heat sealing, a nylon layer having heat resistance and pinhole resistance, and, if necessary, a PET layer having aroma barrier properties. The laminate specifically has a layer structure such as a polyethylene layer / nylon layer or a polyethylene layer / PET layer / nylon layer. The packaging bag can be produced, for example, by applying a seal bar to the nylon layer side of the laminate, raising the temperature of the seal bar to melt the polyethylene layer, and bonding the laminate together. Because the packaging bag falls under the category of plastic container packaging, it is recycled, but mono-materialization is desirable from the perspective of increasing the value of the recycled product, as mentioned above.

[0005] For example, Patent Documents 1 to 10 disclose laminates containing polyethylene as a resin.

[0006] Japanese Patent Laid-Open No. 64-51940 Japanese Patent Publication No. 6-77135 Japanese Patent Laid-Open No. 60-134852 Japanese Patent Laid-Open No. 2018-8456 Japanese Patent Laid-Open No. 2018-62072 Japanese Patent Laid-Open No. 2018-62073 Japanese Patent Laid-Open No. 2019-171860 Japanese Patent Laid-Open No. 2019-171861 Japanese Patent Laid-Open No. 2019-189333 Japanese Patent Laid-Open No. 2019-189334

[0007] From the viewpoint of mono-materialization, the present inventors produced packaging bags using a film consisting of only a polyethylene layer, instead of using a laminate in which a nylon layer or a PET layer is laminated to a polyethylene layer. However, when the temperature of the seal bar was increased during heat sealing, the seal bar fused to the surface of the polyethylene layer, making it impossible to perform heat sealing at a sufficiently high temperature, and sufficient seal strength could not be obtained at the sealed portion. Furthermore, because the seal bar fused to the surface of the polyethylene layer, the appearance of the packaging bag was poor.

[0008] An object of the present invention is to provide a laminate that has excellent heat-sealing properties and is suitable for reuse.

[0009] The laminate according to the present invention comprises a first layer containing only a first polyethylene as a resin and having a melting point Tm1, and a second layer containing only a second polyethylene as a resin and having a melting point Tm ２ and a second layer having Tm １ -Tm ２ ≧24.0°C.

[0010] The packaging bag according to the present invention includes the laminate according to the present invention.

[0011] The method for producing a packaging bag according to the present invention includes a step of heat-sealing the laminate according to the present invention.

[0012] According to the present invention, it is possible to provide a laminate that has excellent heat sealability and is suitable for reuse.

[0013] It is a schematic diagram showing an example of a refill pouch for liquid, which is an example of a packaging bag according to the present invention.

[0014] [Laminate] The laminate according to the present invention comprises a first layer containing only a first polyethylene as a resin and having a melting point Tm1, and a second layer containing only a second polyethylene as a resin and having a melting point Tm ２ The first layer and the second layer are disposed on the outermost surface of the laminate. That is, the first layer is the outermost surface layer on one side of the laminate, and the second layer is the outermost surface layer on the other side of the laminate. Here, the melting point Tm1 and the melting point Tm ２ is Tm １ -Tm ２ ≧24.0°C.

[0015] In the laminate of the present invention, two layers with a melting point difference of 24.0°C or more are laminated as the outermost layers. The first layer, which is a high-melting-point layer, has high heat resistance, so when a sealing bar is applied to the first layer for heat sealing, fusion with the sealing bar can be suppressed even when the temperature of the sealing bar is increased, allowing heat sealing to be performed at high temperatures. Furthermore, the second layer, which is a low-melting-point layer, melts at low temperatures, so it melts easily with heat transferred from the first layer, allowing for adhesion with sufficient sealing strength. Therefore, the laminate of the present invention has excellent heat-sealing properties. Furthermore, because the first and second layers contain only polyethylene as a resin, they are suitable for reuse, allowing for the provision of high-purity, high-value recycled products.

[0016] The laminate according to the present invention includes at least a first layer and a second layer, which are outermost layers, and may include other layers as intermediate layers. Examples of such other layers include functional layers such as a recycled layer, adhesive layer, easy-adhesion layer, printed layer, barrier layer, and easy-open layer. Each functional layer may have multiple functions. The laminate may include one or more of these layers.

[0017] To improve the purity of the recycled product when the laminate is reused, the mass ratio of polyethylene contained in the laminate to 100% by mass of all resins contained in the laminate is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 99% by mass or more, and particularly preferably 100% by mass, i.e., the laminate contains only polyethylene as a resin. The laminate may not contain nylon. Examples of nylon include nylon 6, nylon 6,6, nylon 11, and nylon 12.

[0018] The laminate may contain other components in addition to the resin, such as a thermosetting resin, a metal, a metal oxide, etc. However, from the viewpoint of improving the purity of the recycled product when the laminate is reused, the content of the other components relative to 100% by mass of the laminate is preferably 5% by mass or less, and more preferably 1% by mass or less.

[0019] The thickness of the entire laminate is preferably 10 to 500 μm, and more preferably 50 to 200 μm. The ratio of the total thickness of the first layer and the second layer to the total thickness of the laminate (100%) is preferably 1 to 100%, and more preferably 5 to 100%.

[0020] An example of the laminate according to the present invention is shown in Figure 1. The laminate shown in Figure 1 has a first layer 1 which is a first stretched polyethylene film, a second layer 2 which is a second unstretched polyethylene film, and an adhesive layer 3 which bonds the first layer 1 and the second layer 2. The melting point Tm of the first layer 1 is １ is the melting point Tm of the second layer 2 ２ From the viewpoint of improving the purity of the recycled product when the laminate is reused, it is preferable that the thickness of the adhesive layer 3 is thin, and when the first layer 1 and the second layer 2 can be directly bonded to each other, it is preferable to omit the adhesive layer 3.

[0021] Another example of the laminate according to the present invention is shown in Figure 2. The laminate shown in Figure 2 has a first layer 1 which is a first stretched polyethylene film, a second layer 2 which is a second unstretched polyethylene film, and a recycled layer 4 of the laminate. The laminate also has adhesive layers 3 between the first layer 1 and the recycled layer 4, and between the second layer 2 and the recycled layer 4. The melting point Tm of the first layer 1 １ is the melting point Tm of the second layer 2 ２ 1, the thickness of the adhesive layer 3 is preferably thin, and when the first layer 1 and the recycled layer 4, and the second layer 2 and the recycled layer 4 can be directly bonded, the adhesive layer 3 is preferably omitted. The laminate may have a plurality of recycled layers 4, and may further have other layers.

[0022] (First Layer) The first layer according to the present invention contains only the first polyethylene as a resin. That is, the resin contained in the first layer is entirely the first polyethylene, and the first layer does not contain any other resins than the first polyethylene. The first polyethylene may contain multiple types of polyethylene. In addition, in the present invention, the term "resin" refers to a thermoplastic resin that can be processed by melt extrusion molding.

[0023] Examples of the first polyethylene include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and ethylene-α-olefin copolymers. The first polyethylene may contain one or more of these polyethylenes. Among these, high-density polyethylene (HDPE) is preferred as the first polyethylene from the viewpoint of its high melting point. When the first polyethylene contains HDPE, the mass ratio of HDPE relative to 100% by mass of the first polyethylene is preferably 50% by mass or more, more preferably 70% by mass or more. The first polyethylene may be composed of HDPE or may be composed of HDPE and LLDPE. The first polyethylene may be derived from petroleum-derived materials, plant-derived materials, or a mixture thereof. It may also contain recycled materials.

[0024] The first layer is preferably a stretched film of a first polyethylene. Stretching the first polyethylene can increase the melting point of the first layer. Furthermore, stretching improves pinhole resistance (puncture strength), making the laminate particularly suitable for use in packaging bags for containing liquids. The stretching ratio is preferably 1.2 to 10 times, more preferably 2 to 6 times. Furthermore, the stretching may be uniaxial or biaxial.

[0025] Melting point Tm of the first layer １ is the melting point Tm of the second layer ２ The melting point difference (Tm １ -Tm ２ By making the difference between the melting points 24.0°C or higher, the heat resistance of the first layer can be improved while the second layer can be melted at a low temperature, thereby improving the heat sealability. The upper limit of the range of the melting point difference is not particularly limited, but it can be, for example, 50.0°C or lower. In the present invention, the melting points of the layers are values ​​measured by the DSC method at a heating rate of 10°C / min in accordance with JIS K7121-1987.

[0026] Melting point Tm of the first layer １ is the melting point Tm of the second layer ２ However, from the viewpoint of being able to perform heat sealing at a higher temperature, Tm １ is preferably 130.0°C or higher, more preferably 132.0°C or higher, and even more preferably 135.0°C or higher.

[0027] The thickness of the first layer is preferably 40 μm or less, more preferably 30 μm or less, from the viewpoint of improving thermal conductivity to the second layer during heat sealing. The lower limit of the thickness range of the first layer is not particularly limited, but it can be, for example, 1 μm or more. Furthermore, the ratio of the thickness of the first layer to the total thickness of the laminate (100%) is preferably 10 to 50%, more preferably 15 to 45%, and even more preferably 20 to 40%, from the viewpoint of improving thermal conductivity and adhesiveness to the second layer during heat sealing.

[0028] In addition to the first polyethylene, the first layer may contain, as components other than the resin, additives typically used in polyethylene films, such as lubricants, antioxidants, antiblocking agents, etc. However, the mass ratio of the first polyethylene to 100% by mass of the first layer is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more, and it is particularly preferable that it is 100% by mass, i.e., the first layer consists of the first polyethylene.

[0029] The surface of the first layer may be printed with ink that is removable during the recycling process.

[0030] (Second Layer) The second layer according to the present invention contains only the second polyethylene as a resin. That is, the resin contained in the second layer is entirely the second polyethylene, and the second layer does not contain any other resins than the second polyethylene. The second polyethylene may contain multiple types of polyethylene. Furthermore, the second polyethylene may be a different type of polyethylene from the first polyethylene, or may be the same type of polyethylene as the first polyethylene.

[0031] Examples of the second polyethylene include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and ethylene-α-olefin copolymers. The second polyethylene may contain one or more of these polyethylenes. Among these, linear low-density polyethylene (LLDPE) is preferred as the second polyethylene from the viewpoint of its low melting point. When the second polyethylene contains LLDPE, the mass ratio of LLDPE relative to 100% by mass of the second polyethylene is preferably 50% or more, more preferably 70% or more. Furthermore, the second polyethylene may consist of LLDPE, or may consist of LLDPE and LDPE. When the second polyethylene consists of LLDPE and LDPE, the mass ratio of LLDPE to LDPE is preferably LLDPE / LDPE = 50-90 / 50-10. The second polyethylene may contain LDPE in addition to LLDPE, thereby increasing melt tension and improving moldability. The second polyethylene may be derived from petroleum-derived materials, plant-derived materials, or a mixture thereof. It may also contain recycled materials.

[0032] The second layer is preferably a non-oriented film of a second polyethylene, since the second polyethylene is not oriented, the melting point of the second layer can be lowered.

[0033] Melting point Tm of the second layer ２ is the melting point Tm of the first layer １ However, from the viewpoint of being able to melt sufficiently at a lower temperature and obtain a high seal strength, Tm ２ is preferably 115.0°C or less, more preferably 110.0°C or less, and even more preferably 107.0°C or less.

[0034] The thickness of the second layer is preferably 50 μm or more, more preferably 60 μm or more, from the viewpoint of ensuring sufficient adhesion during heat sealing. The upper limit of the thickness range of the second layer is not particularly limited, but can be, for example, 400 μm or less. The ratio of the thickness of the second layer to the total thickness (100%) of the laminate is preferably 50 to 90%, more preferably 55 to 85%, and even more preferably 60 to 80%, from the viewpoint of improving thermal conductivity and adhesiveness to the second layer during heat sealing.

[0035] The ratio of the thickness of the second layer to the total thickness of the first layer and the second layer (100%) is preferably 50 to 90%, more preferably 55 to 85%, and even more preferably 60 to 80%, from the viewpoint of improving thermal conductivity and adhesiveness to the second layer during heat sealing.

[0036] In addition to the second polyethylene, the second layer may contain, as components other than the resin, additives typically used in polyethylene films, such as lubricants, antioxidants, antiblocking agents, etc. However, the mass ratio of the second polyethylene to 100% by mass of the second layer is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more, and it is particularly preferable that the mass ratio is 100% by mass, i.e., the second layer consists of the second polyethylene.

[0037] (Recycled Layer) From the viewpoint of environmental conservation, the laminate of the present invention preferably further comprises a recycled layer of the laminate of the present invention in addition to the first layer and the second layer. The recycled layer can be produced, for example, by crushing, cleaning, re-melting and extruding scraps or non-standard products generated during the production of the laminate of the present invention and packaging bags produced using the laminate, or used laminates or packaging bags distributed on the market, and molding them into a film.

[0038] From the viewpoint of improving the purity of the recycled product when reusing the laminate, the mass ratio of polyethylene contained in the recycled layer to 100% by mass of all resins contained in the recycled layer is preferably 90% by mass or more, and more preferably 99% by mass or more.

[0039] The thickness of the recycled layer is not particularly limited, but is preferably 2 to 400 μm, more preferably 10 to 200 μm. The ratio of the thickness of the recycled layer to the total thickness of the laminate (100%) is preferably 1 to 99%, more preferably 10 to 90%.

[0040] The fact that a layer included in the laminate is a recycled layer can be determined, for example, by having two or more glass transition temperatures or melting points, or by including an adhesive. The glass transition temperature and melting point can be confirmed by DSC (Differential Scanning Calorimetry). The presence or absence of an adhesive can be confirmed by chemical analysis such as IR (Infrared spectroscopy).

[0041] (Adhesive Layer) The laminate according to the present invention may optionally include an adhesive layer for adhering the layers constituting the laminate. For example, when the first layer is a stretched film, the film-like first layer and other layers can be adhered to each other via an adhesive layer. Examples of adhesives included in the adhesive layer include urethane-based, acid-modified polyolefin-based, polyester-based, polyether-based, and polyamide-based adhesives. The adhesive layer may include one type of these adhesives or two or more types.

[0042] The thickness of the adhesive layer is not particularly limited, but may be, for example, 0.1 to 10 μm. The ratio of the adhesive layer thickness to the total thickness of the laminate (100%) may be, for example, 0.01 to 10%. When the laminate has multiple adhesive layers, the ratio indicates the ratio of the total thickness of all adhesive layers to the total thickness of the laminate (100%). From the viewpoint of improving the purity of the recycled product when reusing the laminate, a thinner adhesive layer is preferable, and it is more preferable to not provide an adhesive layer.

[0043] (Physical properties of laminate) The laminate according to the present invention preferably has a puncture strength of 5 N or more, more preferably 6 N or more, and even more preferably 6.5 N or more. When the puncture strength is within the above range, pinhole resistance is high and liquid leakage can be sufficiently suppressed, particularly when the laminate is used to produce a packaging bag for containing liquid. The upper limit of the puncture strength range is not particularly limited. The puncture strength is measured in accordance with JIS Z1707 (1997), and the number of measurements, n = 3, is taken as the average value.

[0044] (Method for Producing Laminate) The method for producing the laminate according to the present invention is not particularly limited, and the laminate can be produced, for example, by co-extruding the material constituting the first layer, the material constituting the second layer, and, if necessary, the material of other layers such as recycled layers. Furthermore, when the first layer is a stretched film, the laminate can be produced, for example, by bonding the film of the first layer, the film of the second layer, and, if necessary, other layers such as recycled layers via the adhesive layer.

[0045] [Packaging Bag] The packaging bag of the present invention includes the laminate of the present invention. The packaging bag of the present invention may be made of the laminate of the present invention. The packaging bag of the present invention can be formed by heat-sealing the second layer of the laminate of the present invention as the adhesive surface, and has high seal strength because it can be heat-sealed at high temperatures. Therefore, even when a liquid is filled inside the packaging bag, leakage of the liquid can be suppressed. Furthermore, even when a seal bar is brought into contact with the surface of the first layer of the laminate and heat-sealed at high temperatures, melting of the surface is suppressed, resulting in a good appearance of the packaging bag. Furthermore, since the packaging bag is made of the laminate of the present invention, it is suitable for reuse. In particular, when the first layer is a stretched film, it has high pinhole resistance and is therefore suitable as a packaging bag for containing liquid.

[0046] FIG. 3 shows an example of a liquid refill pouch as an example of a packaging bag for containing liquid according to the present invention. The liquid refill pouch shown in FIG. 3 has a body 5 and a bottom 6. The body 5 is composed of two laminates according to the present invention, and the bottom 6 is composed of one laminate according to the present invention. Side seals 7 and a top seal 9 are formed by heat-sealing the two laminates that make up the body 5. A bottom seal 8 is formed by heat-sealing the two laminates that make up the body 5 to the single laminate that makes up the bottom 6. A nozzle 10 protruding upward is provided at one corner of the upper part of the body 5. A perforation line 11 is provided in the nozzle 10, and a tip 12 of the nozzle 10 is cut along the perforation line 11 to form a spout for extracting the contents. The spout can be inserted into the inlet of another container, such as a plastic bottle or a glass bottle, and the contents can be poured into the other container by tilting the refill pouch. Examples of contents of liquid refill pouches include detergent, bleach, fabric softener, laundry starch, shampoo, conditioner, cosmetics, deodorant, etc.

[0047] [Method for manufacturing packaging bag] The method for manufacturing a packaging bag according to the present invention includes a step of heat-sealing the laminate according to the present invention. Since the method produces a packaging bag using the laminate according to the present invention, a packaging bag having excellent heat-sealability and high seal strength at the sealed portion can be obtained. Furthermore, since melting of the surface can be suppressed during heat sealing, a packaging bag with good appearance can be obtained.

[0048] An example of a method for manufacturing a packaging bag according to the present invention is shown below. First, two laminates according to the present invention are prepared and stacked so that the second layers face each other. Next, a sealing bar set to a predetermined temperature is applied to the surface of the first layer corresponding to the sealing portion. The temperature at which the laminate is heat-sealed is set to the melting point Tm of the first layer. １Although it depends on the temperature, from the viewpoint of sufficiently melting the second layer and obtaining high seal strength, the temperature is preferably 130°C or higher, more preferably 145°C or higher, and even more preferably 160°C or higher. The sealed portion can be formed leaving one side for filling the contents. This results in a packaging bag. The contents are then filled from the remaining open side, and the remaining side is heat-sealed to obtain a packaging bag filled with the contents.

[0049] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. The melting points, upper seal temperature limits, seal strength, and puncture strength of the layers were measured by the following methods.

[0050] [Melting Point of Layers] The melting point of each layer was measured in accordance with JIS K7121-1987 using a DSC (manufactured by PerkinElmer) at a temperature rise rate of 10°C / min. When multiple peaks were observed, the main peak with the largest endothermic heat was taken as the melting point.

[0051] [Upper limit sealing temperature] Two laminates were stacked with the second layers facing each other, and a seal bar set at a predetermined temperature was applied to the first layer to perform heat sealing. The upper limit sealing temperature was the temperature limit at which the surface of the first layer could be sealed without melting. The presence or absence of melting of the surface of the first layer was confirmed visually.

[0052] [Seal Strength] The seal strength was measured in accordance with JIS Z 0238 (1998) using an autograph (manufactured by Shimadzu Corporation) at a pulling speed of 300 mm / min and a test piece width of 15 mm.

[0053] [Piercing Strength] The piercing strength of the laminate was measured in accordance with JIS Z1707 (1997). The number of measurements (n=3) was measured, and the average value was taken as the measured value.

[0054] Example 1 As shown in FIG. 1 , a laminate was produced in which a first layer 1 and a second layer 2 were bonded together by an adhesive layer 3. Specifically, a uniaxially oriented HDPE film (melting point: 139.0°C, thickness: 25 μm) was prepared as the first layer, and an unstretched LLDPE film (melting point: 107.0°C, thickness: 60 μm) was prepared as the second layer. The first layer and the second layer were bonded together using a urethane adhesive (coating amount: 3.5 g / m ２ The first and second layers were dry-laminated using a dry lamination machine to obtain a laminate. The melting points, upper seal temperature limits, seal strength, and puncture strength of the first and second layers were measured using the methods described above. The results are shown in Table 1.

[0055] [Example 2] A uniaxially stretched HDPE film (melting point: 132.2°C, thickness: 25 µm) was used as the first layer. Otherwise, a laminate was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0056] Example 3 A uniaxially stretched HDPE film (melting point: 132.2°C, thickness: 30 μm) was used as the first layer. Otherwise, a laminate was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0057] Example 4 A laminate was produced in which the first layer 1 and the recycled layer 4, and the second layer 2 and the recycled layer 4, as shown in FIG. 2, were bonded together by the adhesive layer 3. The packaging bag produced in Example 6, which will be described later, was crushed using a plastic crusher. The crushed material was fed to a twin-screw extruder (barrel set temperature: 240°C) equipped with a granulation system and re-pelletized. The re-pelletized material was further fed to a single-screw extruder (T-die and barrel set temperature: 255°C) equipped with a 300 mm wide T-die and film take-up system to produce a recycled film with a thickness of 30 μm.

[0058] Subsequently, blend pellets of LLDPE resin (MFR: 0.8 g / min) and LDPE resin (MFR: 2.0 g / min) mixed at a mass ratio of LLDPE / LDPE = 7 / 3 were fed into a single-screw extruder (T-die and barrel set temperature: 200°C) equipped with a 300 mm wide T-die and film take-up equipment to produce a 30 μm thick film for the second layer. The melting point of this film was 107.0°C.

[0059] Furthermore, a urethane adhesive (coating amount 3.5 g / m) was applied between the first layer used in Example 2 and the film that would become the second layer so that the recycled film would be sandwiched as a recycled layer. ２ These films were dry-laminated using a dry lamination machine to obtain a laminate.

[0060] Comparative Example 1 A non-stretched HDPE film (melting point: 130.6°C, thickness: 30 µm) was used as the first layer. Otherwise, a laminate was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0061] Comparative Example 2 A laminate was produced and evaluated in the same manner as in Example 1 except that an unstretched HDPE film (melting point: 128.9°C, thickness: 40 µm) was used as the first layer. The results are shown in Table 1.

[0062]

[0063] As shown in Table 1, the melting point Tm of the first layer １ and the melting point Tm of the second layer ２ Difference from (Tm １ -Tm ２ In Examples 1 to 4, where the melting point difference (Tm) was 24.0°C or higher, the upper seal temperature limit was high and the second layer was sufficiently melted during heat sealing, resulting in high seal strength. In addition, since a stretched film was used for the first layer, the puncture strength was high. １ -Tm ２ In Comparative Examples 1 and 2, where the upper limit sealing temperature was less than 24.0°C, the upper limit sealing temperature was lower and the seal strength was lower than in Examples 1 to 4. In addition, because an unstretched film was used for the first layer, the puncture strength was lower than in Examples 1 to 4. The resin type in the column for the type of the first layer and the second layer indicates the resin type contained as the main component.

[0064] Example 5 A packaging bag (130 mm x 213 mm) with one side open was produced using the laminate produced in Example 1. Specifically, two laminates produced in Example 1 were prepared and stacked so that the second layers faced each other. Next, a sealing bar set at 180°C was applied to the surface of the first layer corresponding to the sealed portion. The sealed portion was formed, leaving one side for filling the contents. This resulted in a packaging bag. 300 g of water was then filled as the contents through the remaining open side, and the other side was similarly heat-sealed at 180°C to produce a packaging bag filled with the contents. The packaging bag filled with the contents was dropped five times from a height of 100 cm in a position horizontal to the floor, and no breakage occurred.

[0065] [Example 6] A packaging bag filled with a content was produced in the same manner as in Example 5, except that the laminate produced in Example 2 was used as the laminate and the set temperature of the seal bar was changed to 155° C. The packaging bag filled with the content was dropped five times from a height of 100 cm in a position parallel to the floor, and no breakage occurred in the bag.

[0066] [Example 7] A packaging bag filled with a content was produced in the same manner as in Example 5, except that the laminate produced in Example 3 was used as the laminate and the set temperature of the seal bar was changed to 155° C. The packaging bag filled with the content was dropped five times from a height of 100 cm in a position parallel to the floor, and no breakage occurred in the bag.

[0067] [Example 8] A packaging bag filled with a content was produced in the same manner as in Example 5, except that the laminate produced in Example 4 was used as the laminate and the set temperature of the seal bar was changed to 155° C. The packaging bag filled with the content was dropped five times from a height of 100 cm in a position parallel to the floor, and no breakage occurred in the bag.

[0068] [Comparative Example 3] A packaging bag filled with contents was produced in the same manner as in Example 5, except that the laminate produced in Comparative Example 1 was used as the laminate and the set temperature of the seal bar was changed to 135° C. When the packaging bag filled with the contents was dropped from a height of 100 cm in a position parallel to the floor, the bag broke.

[0069] [Comparative Example 4] A packaging bag filled with contents was produced in the same manner as in Example 5, except that the laminate produced in Comparative Example 2 was used as the laminate and the set temperature of the seal bar was changed to 135° C. When the packaging bag filled with the contents was dropped from a height of 100 cm in a position parallel to the floor, the bag broke.

[0070] REFERENCE SIGNS LIST 1 First layer 2 Second layer 3 Adhesive layer 4 Recycled layer 5 Body 6 Bottom 7 Side seal 8 Bottom seal 9 Top seal 10 Nozzle 11 Perforation line 12 Tip

Claims

DEPCT661. A laminate composed of a first layer with a fused set Tm1 and containing only polyethylene type I as the resin; and a second layer with a fused set Tm2 and containing only polyethylene type II as the resin, where: the first and second layers are arranged respectively as the outermost surfaces of the laminate; and Tm1-Tm2 greater than or equal to 24.0 degrees Celsius are conformed.

2. A laminate according to claim 1, where the first layer is a stretched film of polyethylene type I.

3. A laminate 1. Laminate under claim 1 or 2, where the second layer is a non-stretchable film of polyethylene II.

4. Laminate under any of claims 1 to 3, where polyethylene I contains high-density polyethylene (HDPE).

5. Laminate under any of claims 1 to 4, where polyethylene II contains linear low-density polyethylene (LLDPE).

6. Laminate under any of claims 1 to 5, which is further incorporated with a recycled layer from the laminate. 7.

7. Laminates under any of the claims 1 through 6, where the second layer has a thickness ratio of 50 to 90% versus 100% for the total thickness of the first and second layers.

8. Laminates under any of the claims 1 through 7, where the mass ratio of polyethylene contained in the laminate is 90% by mass or more versus 100% by mass for all resins contained in the laminate.

9. Laminates under any of the claims 1 through 8, where the laminate does not contain nylon.

10. Packaging bags incorporating laminates under any of the claims 1 through 9.

11. Packaging bags under claim 10, for the storage of liquids.

12. Methods of manufacturing packaging bags, incorporating heat sealing of laminates under any of the claims 1 through 9.

13. Methods of manufacturing packaging bags under claim 12, where the temperature for heat sealing is 130 degrees Celsius or higher.