Laminate and packaging container

Abstract

To provide a laminate suitable for recycling, from which it is possible to manufacture a film for a heat seal layer similar to a film for a heat seal layer in the laminate of the present invention, by using a recycled resin from a packaging container or the like comprising the laminate of the present invention.SOLUTION: Provided is a laminate including a base material layer having a melting point Tm1 in at least an outer layer, and a heat seal layer having a melting point Tm2 in an inner layer, characterized by 24°C≤Tm1-Tm2≤152°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate and a packaging bag. [Background technology]

[0002] Conventionally, polyethylene terephthalate (hereinafter referred to as "PET") bottles and plastic containers and packaging have been subject to the Container and Packaging Recycling Law, and because ordinary PET bottles contain only PET resin as the resin, they are easy to recycle, and horizontal recycling has been established. On the other hand, plastic containers and packaging usually contain multiple types of resin, and because it is difficult to separate these multiple types of resin, various problems arise when recycling them.

[0003] One example of such plastic container packaging is a packaging bag that uses a laminate produced by using a PET film for the base film and a polyethylene film for the heat-seal layer, molding the two films separately, and then dry-laminating them with a urethane adhesive or the like (see, for example, Patent Document 1). Here, the polyethylene film used for the heat-seal layer uses low-density polyethylene or linear low-density polyethylene as the main resin, and its melting point is generally about 110°C, although it depends on the product grade. The melting point of the PET used for the base film is generally about 260°C, although it also depends on the product grade.

[0004] Therefore, when the recycled resin obtained by crushing the packaging bags is reused to produce a heat-sealable film similar to the heat-sealable film in the laminate, the molding temperature for the film must be set to approximately 280°C, slightly higher than the melting point of PET, because the recycled resin contains PET. However, molding the film at approximately 280°C is too high for the low-melting-point decomposition products contained in the polyethylene film, such as paraffin oil and low-molecular-weight compounds, and can result in problems such as carbonization of the low-melting-point decomposition products, the generation of large amounts of oily smoke during molding, contamination of the extrusion rolls, and an increase in molding pressure during extrusion. Therefore, if the molding temperature is set lower than 280°C, the PET will not melt sufficiently, resulting in problems such as fisheyes and pinholes, which can lead to a decrease in film quality.

[0005] Additionally, laminates for packaging containers that use polyamide as a base material and have excellent pinhole resistance are also known (see, for example, Patent Document 2). However, polyamide may be a contraindicated substance when chemical recycling is performed, and therefore, in consideration of recycling in general, it is thought that its use in such laminates should be avoided as much as possible. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-154135 [Patent Document 2] Japanese Patent Publication No. 2022-163548 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above circumstances, an object of the present invention is to provide a laminate suitable for re-recycling, which can be used to produce a film for a heat seal layer similar to the film for a heat seal layer in the laminate of the present invention using resin recycled from packaging containers, etc. made of the laminate of the present invention. It is still another object of the present invention to provide a packaging container formed using the above laminate suitable for recyclability. Here, re-recycling means manufacturing the "packaging containers, etc. manufactured using recycled resin" again using recycled resin made from "packaging containers, etc. manufactured using recycled resin." [Means for solving the problem]

[0008] According to the present invention, there is provided a laminate comprising at least an outer substrate layer having a melting point Tm1 and an inner heat seal layer having a melting point Tm2, ​​wherein 24°C≦Tm1−Tm2≦152°C.

[0009] The sealant film of the present invention preferably employs the following aspects. (1) The heat seal layer is composed of at least three layers, with a recycled layer between two layers made of virgin polyolefin. (2) The recycled layer has a melting point Tm3, and Tm3≦250°C. (3) The substrate layer is made of a stretched polybutylene terephthalate film. (4) The virgin polyolefin in the heat seal layer is polyethylene, and all three layers in the heat seal layer are unstretched films. (5) A vapor-deposited layer using an inorganic substance or an inorganic oxide is provided between the substrate layer and the heat seal layer. (6) At least one of the two layers made of virgin polyolefin is a colored layer. (7) The base layer and the heat seal layer are laminated together using an adhesive. (8) The laminate does not contain polyethylene terephthalate and polyamide. (9) A packaging container using the laminate. [Effects of the Invention]

[0010] The laminate of the present invention comprises at least an outer substrate layer having a melting point Tm1 and an inner heat-seal layer having a melting point Tm2, ​​wherein 24°C ≦ Tm1 - Tm2 ≦ 152°C, and a film for a heat-seal layer similar to that in the laminate can be produced using resin recycled from packaging containers, etc., comprising the laminate, making the laminate suitable for recyclability. By keeping the difference between the melting points Tm1 and Tm2 within the above numerical range, the molding temperature during recycling can be set low, thereby preventing problems such as carbonization of low-melting-point decomposition products contained in the polyethylene film, generation of oily smoke, contamination of extrusion molding rolls, and increased molding pressure during extrusion.

[0011] Furthermore, in the laminate of the present invention having the layer structure described above, by utilizing this layer structure and forming a vapor-deposited layer using an inorganic substance or inorganic oxide between the base layer and the heat-sealable layer, the gas barrier properties of the laminate can be improved. Also, by making at least one of the two layers made of virgin polyolefin a colored layer, the appearance characteristics can be improved. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional side view showing the layer structure of a first embodiment of the laminate of the present invention. [Figure 2] FIG. 3 is a schematic cross-sectional side view showing the layer structure of a second embodiment of the laminate of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional side view showing the layer structure of a third embodiment of the laminate of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional side view showing the layer structure of a fourth embodiment of the laminate of the present invention. [Figure 5] 1 is a schematic diagram showing an example of a liquid refill pouch, which is an example of a packaging container according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments. Note that, since the laminate of the present invention is used in a heat-sealed packaging container, in the packaging container, the heat-seal layer side is the inner layer and the base layer side is the outer layer.

[0014] <Laminate> FIG. 1 is a schematic cross-sectional side view showing the layer structure of a first embodiment of the laminate of the present invention. The laminate 100 is composed of three layers: a heat-seal layer 4 consisting of two virgin polyolefin layers 2 and a recycled layer 3 sandwiched between them; and the heat-seal layer 4 and a base layer 1 are dry-laminated with an adhesive layer 5. The thickness of the base layer 1 is preferably 40 μm or less, more preferably 30 μm or less, from the viewpoint of improving thermal conductivity to the heat-seal layer 4 during heat-sealing. While the lower limit of the thickness is not particularly limited, it is preferably, for example, 1 μm or more. Furthermore, the thickness of the heat-seal layer 4 is preferably 50 μm or more, more preferably 60 μm or more, from the viewpoint of ensuring sufficient adhesion during heat-sealing. While the upper limit of the thickness of the heat-seal layer 4 is not particularly limited, it is preferably, for example, 500 μm or less, more preferably 400 μm or less. The thickness of the recycled layer 3 is not particularly limited, but is preferably 2 to 400 μm, more preferably 10 to 200 μm. The thickness of the adhesive layer 5 is not particularly limited, but is preferably set to, for example, 0.1 to 30 μm.

[0015] The virgin polyolefin layer 2 is produced using virgin polyolefin. The virgin polyolefin is not particularly limited as long as it is a virgin polyolefin having heat-sealability. However, it is preferable to use polyethylene selected from low-density polyethylene (LDPE) or linear low-density polyethylene (LLDPE), or unstretched polypropylene (CPP), and it is more preferable to use polyethylene. Different polyolefins may also be used in combination, such as a mixture of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE). The polyolefin may be derived from petroleum-derived materials, plant-derived materials, or a mixture thereof. It is also preferable that all three layers in the heat-sealable layer 4 are unstretched films, as this provides excellent heat-sealability.

[0016] The recycled layer 3 contains a so-called recycled resin obtained by subjecting recovered used plastic packaging containers or waste materials recovered during the manufacture of plastic packaging containers to various processes, such as crushing, washing with alkali, filtration in a molten state, and extraction with an organic solvent. The recycled resin preferably does not contain PET to lower the molding temperature during film formation, and preferably contains almost no polyamide, which may be a contraindication substance during chemical recycling. Since the resin used is known, it is preferable to use a recycled resin made from waste materials or products recovered during the manufacture of the laminate of the present invention, and it is even more preferable to use a recycled resin made from waste materials recovered during the manufacture of the virgin polyolefin layer 2. Here, "almost free of polyamide" means that the recycled resin does not contain any polyamide, or even if it does contain any polyamide, the amount is 5% by mass or less relative to the total amount of the recycled resin.

[0017] The heat seal layer 4 contains a recycled resin in the recycled layer 3, but as the proportion of recycled resin used increases, the amount of virgin polyolefin used in the heat seal layer 4 etc. decreases relatively, resulting in a significant deterioration in heat sealability and other physical properties. Therefore, from the viewpoint of avoiding such deterioration in physical properties, the recycled resin content in the heat seal layer 4 is preferably 15 to 90 mass %, more preferably 15 to 60 mass %.

[0018] Furthermore, in order to more reliably avoid a decrease in the heat sealability of the heat seal layer 4, it is preferable that, for example, when the thickness of the recycled layer 3 is 100 μm, the thickness of the virgin polyolefin layers 2 on both the upper and lower sides be set to approximately 10 to 60 μm (10 to 60% of the thickness of the heat seal layer 4).

[0019] Furthermore, the recycled layer 3 may be formed solely of recycled resin, but preferably contains virgin polyolefin. Assuming that the recycled resin content in the heat-seal layer 4 satisfies the aforementioned numerical range and the thickness ratio between the recycled layer 3 and the upper and lower virgin polyolefin layers 2, the mass ratio of recycled resin to virgin polyolefin is preferably within the range of 99:1 to 25:75. A 50:50 ratio indicates a two-fold dilution, and a 25:75 ratio indicates a four-fold dilution. The recycled layer 3 is formed by co-extrusion molding recycled resin-containing pellets and virgin polyolefin pellets. Furthermore, the melting point Tm3 of the recycled layer 3 is preferably Tm3≦250°C, more preferably Tm3≦240°C, and particularly preferably Tm3≦230°C, because polyolefins deteriorate at molding temperatures above 250°C. Furthermore, the virgin polyolefin used in the recycled layer 3 is preferably the same as the virgin polyolefin used in the virgin polyolefin layer 2, but may be different. Furthermore, since the recycled layer 3 contains components such as polyester resin, adhesive, and colorant, an ester decomposition inhibitor such as a carbodiimide compound may be added to suppress a decrease in strength due to a decrease in molecular weight caused by these components, and a compatibilizer may also be added to improve dispersibility. The polar group of the compatibilizer may include an organic isocyanate group, a carboxylic acid anhydride group, a carboxylic acid group, an amino group, a hydroxyl group, an epoxy group, or an acrylic ester group, and acid-modified olefin resins or imine-modified olefin resins, acrylic ester-glycidyl methacrylate copolymer olefin resins, and saponified ethylene-vinyl acetate copolymers are preferred. Other additives that may be added include lubricants, ultraviolet absorbers, plasticizers, crystal nucleating agents, fillers, hydrolysis inhibitors, flame retardants, antistatic agents, anti-fogging agents, and anti-blocking agents, as long as they do not impair the physical properties.

[0020] The base layer 1 has a melting point Tm1, and a resin having a melting point Tm1 lower than the melting point of PET, which is approximately 260°C, can be used. Examples of such resins include polybutylene terephthalate (melting point 230°C), high-density polyethylene (melting point 130 to 150°C), oriented polypropylene (OPP, melting point 165°C), polystyrene (melting point 240°C), polyvinylidene chloride (melting point 210°C), polychlorotrifluoroethylene (melting point 220°C), acetylcellulose (melting point 230°C), polysulfone (melting point 200°C), polycarbonate (melting point 150°C), polyacetal (melting point 181°C), ethylene-vinyl alcohol copolymer (melting point 160 to 183°C), and polyvinyl alcohol (melting point 200°C). Among these, polybutylene terephthalate, polystyrene, polyvinylidene chloride, polychlorotrifluoroethylene, and acetylcellulose, which have melting points in the range of 210 to 240° C., are preferred, and polybutylene terephthalate is more preferred. These may be used alone or in combination.

[0021] The present invention is characterized by a laminate including at least an outer substrate layer having a melting point Tm1 and an inner heat-seal layer having a melting point Tm2, ​​wherein Tm1-Tm2 satisfies 24°C≦Tm1-Tm2≦152°C. For example, when uniaxially oriented high-density polyethylene (melting point Tm1: 134°C) is used for the substrate layer and unoriented low-density polyethylene (melting point Tm2: 110°C) is used for the heat-seal layer, Tm1-Tm2 is 24 (134-110=24)°C. When the substrate layer is replaced with polybutylene terephthalate (melting point Tm1: 225°C), Tm1-Tm2 is 120 (225-110=115)°C. The melting points were measured using a differential scanning calorimeter (DSC).

[0022] Furthermore, it is more preferable that Tm1-Tm2 satisfies the relationship 51° C.≦Tm1-Tm2≦125° C. For example, when oriented polypropylene (melting point Tm1: 165° C.) is used for the base layer and unoriented low-density polyethylene (melting point Tm2: 110° C.) is used for the heat-sealable layer, Tm1-Tm2 is 55 (165-110=55)° C.

[0023] The heat seal layer 4 is produced by cast film production using three or five extruders to produce a laminate consisting of two virgin polyolefin layers 2 and two recycled layers 3, or a three-type, five-type laminate as shown in Figure 4 below. The components are dry-blended and fed into the extruders for melt-kneading, co-extruded into a film from a T-die, and the extruded two-type, three-layer, or three-type, five-layer film is solidified by contacting it with a cooling roll and wound up. The components may be added in the form of film-like fragments, pellets, granules, or liquid. The film-like fragments may be film scraps generated during the implementation of the present invention. In inflation molding, which is typically used to extrude bag-shaped films to produce heat sealant films, the presence of incompatible foreign matter in the polyolefin tends to result in holes and thickness variations. Passing the material through a fine-mesh filter to remove the foreign matter significantly reduces production speed. In contrast, cast film production makes it easy to obtain high-quality films with no holes and little thickness deviation, and since there is no need to pass the film through a fine-mesh filter, it is possible to suppress a decrease in production speed. Here, the heat-seal layer 4 is not limited to the two-kind three-layer or three-kind five-layer configuration, and any number of types and layers can be used as needed, but since it includes the recycled layer 3, it is preferably composed of at least three layers.

[0024] The base material layer 1 is formed by a known means or method using an extruder or the like, separately from the heat seal layer 4. Since it is used as an outer layer and therefore requires improved film strength, thermal properties, etc., the base material layer 1 is preferably a stretched film, and the stretching may be either uniaxial or biaxial, but biaxial stretching is more preferred since it further improves the film strength, etc.

[0025] The base material layer 1 and the heat seal layer 4 are laminated using an adhesive layer 5 made of an adhesive. Examples of the adhesive include known adhesives such as urethane-based, epoxy-based, acid-modified polyolefin-based, polyester-based, polyether-based, and polyamide-based adhesives. The adhesive layer 5 may contain one or more of these adhesives. It is preferable that the adhesive layer 5 contains a urethane-based adhesive because it is flexible and impact-resistant.

[0026] FIG. 2 is a schematic cross-sectional side view showing the layer structure of a second embodiment of the laminate of the present invention, and shows a laminate 200 having, in addition to the layer structure of the first embodiment shown in FIG. 1, a vapor-deposited layer 6 using an inorganic substance or inorganic oxide on the surface of the base layer 1 facing the heat seal layer 4.

[0027] The inorganic substance may be silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), or the like, but aluminum (Al) is preferred as it is suitable for packaging containers.

[0028] The inorganic oxides include SiO X , AlO X MO etc. X(wherein, M represents an inorganic element, and the value of X varies depending on the inorganic element.) Here, the value of X can range from 0 to 2 for silicon (Si), 0 to 1.5 for aluminum (Al), 0 to 1.5 for magnesium (Mg), 0 to 1 for calcium (Ca), 0 to 1 for potassium (K), 0 to 0.5 for tin (Sn), 0 to 2 for sodium (Na), 0 to 0.5 for boron (B), 0 to 1.5 for titanium (Ti), 0 to 2 for lead (Pb), 0 to 1 for zirconium (Zr), and 0 to 1.5 for yttrium (Y). However, in the above, when X = 0, it is completely inorganic, not an inorganic oxide, and is therefore excluded. Silicon oxide or aluminum oxide is preferred as a material suitable for packaging containers, and SiO2 or AlO2 is particularly preferred due to their transparent appearance.

[0029] The vapor-deposited layer 6 is formed using a known technique such as plasma CVD, and has the effect and function of improving the gas barrier properties of the laminate and concealing coloration caused by recycled resins when the laminate 200 is used as a packaging container. Such a vapor-deposited layer 6 is a thin layer having a thickness of about 0.001 to 1 μm. To further improve the gas barrier properties, the thin layer may contain a coating film formed by a crosslinking reaction between carboxylic acid and metal, or a coating film in which metal oxide is dispersed.

[0030] FIG. 3 is a schematic cross-sectional side view showing the layer structure of a third embodiment of the laminate of the present invention. This structure is similar to that of the first embodiment shown in FIG. 1 , but the heat-seal layer 4 is composed of three layers: two colored virgin polyolefin layers 7 containing a coloring pigment, and a recycled layer 8 containing a recycled resin obtained from packaging containers made from the laminate of the present invention. The heat-seal layer 4 and the base layer 1 are dry-laminated with an adhesive layer 5 to form a laminate 300. Here, except that the colored virgin polyolefin layer 7 contains a coloring pigment, and the recycled layer 8 contains a recycled resin obtained from packaging containers made from the laminate of the present invention, the thickness and material composition can be the same as those of the virgin polyolefin layer 2 and the recycled layer 3, respectively. The colored virgin polyolefin layer 7 has the effect and function of concealing the coloring caused by the recycled resin when the laminate 300 is used for packaging containers. Furthermore, the laminate 300 has colored virgin polyolefin layers 7 on both sides of the recycled layer 8, but a virgin polyolefin layer 3 that does not contain a coloring pigment may be used on one side. In this case, in order to exert the above-mentioned effects and functions, it is preferable that the outer layer side of the recycled layer 8 be the colored virgin polyolefin layer 7 and the inner layer side be the virgin polyolefin layer 3.

[0031] The color pigment contained in the colored virgin polyolefin layer 7 may be any known color pigment, such as white pigments such as titanium oxide, zinc white, calcium carbonate, etc., black pigments such as carbon black, iron black, etc., red pigments such as red iron oxide, cadmium red, molybdenum orange, etc., blue pigments such as cobalt aluminate, Prussian blue, etc., and yellow pigments such as cadmium yellow, etc. When a printed layer containing a trade name, pattern, etc. is provided on either side of the base layer 1, it is preferable to use a white pigment, considering that the colored virgin polyolefin layer 7 serves as a printing base layer.

[0032] FIG. 4 is a schematic cross-sectional side view showing the layer structure of a fourth embodiment of the laminate of the present invention. The laminate 400 includes a base layer 1 having a printed layer (not shown) on its bottom surface, a base layer 1 having a vapor-deposited layer 6 on its top surface, and a heat-seal layer 4 dry-laminated with two adhesive layers 5. The heat-seal layer 4 includes two virgin polyolefin layers 2, two recycled white virgin polyolefin layers 9 containing a recycled resin made from a packaging container formed from the laminate of the present invention and a white pigment, and a further recycled layer 10 containing the recycled resin contained in the recycled layer 3, a recycled resin made from a packaging container formed from the laminate of the present invention, and a virgin polyolefin. Regarding the recycled white virgin polyolefin layer 9, if the recycled resin is highly colored, the appearance of the laminate 400 may be impaired. To avoid this problem, if the recycled resin is highly colored, the recycled white virgin polyolefin layer 9 may contain only a white pigment without the recycled resin.

[0033] The laminates 100 to 400 of the first to fourth embodiments are not limited to the respective embodiments, and the layers can be combined as needed. For example, the vapor-deposited layer 6 of the laminate 200 can be combined with the laminate 300, the colored virgin polyolefin layer 7 of the laminate 300 can be combined in place of the virgin polyolefin layer 2 of the laminates 100 and 200, and the heat-seal layer 4 of the laminate 400 can be combined in place of the heat-seal layer 4 of the laminates 100 to 300.

[0034] In the laminate of the present invention having the above-described layer structure, each layer may contain, as a component other than the resin, known additives that are used in ordinary resins, such as deodorants, antioxidants, lubricants, modifiers, and antiblocking agents.

[0035] <Packaging container> FIG. 5 is a schematic diagram showing an example of a liquid refill pouch, which is an example of a packaging container according to the present invention. The liquid refill pouch has a body 11 and a bottom 12. The body 11 is composed of two laminates according to the present invention, and the bottom 12 is composed of one laminate according to the present invention or a laminate made of virgin material. Side seals 13 and a top seal 15 are formed by heat-sealing the two laminates that make up the body 11. A bottom seal 14 is formed by heat-sealing the two laminates that make up the body 11 and the single laminate that makes up the bottom 12. A nozzle 16 protruding upward is provided at one corner of the upper part of the body 11. A perforation line 17 is provided in the nozzle 16, and a tip 18 of the nozzle 16 is cut along the perforation line 17 to form a spout for dispensing the contents. The contents can be poured into another container by inserting the spout into the injection port of the other container, such as a plastic bottle or a glass bottle, and tilting the refill pouch. Examples of contents of liquid refill pouches include detergent, bleach, fabric softener, laundry starch, shampoo, conditioner, cosmetics, deodorant, etc.

[0036] 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. Since the laminate according to the present invention is used to produce a packaging container in this production method, the resulting packaging container has excellent heat-sealing properties and high sealing strength at the sealed portion. Furthermore, since melting of the surface during heat sealing can be suppressed, the resulting packaging container has a good appearance.

[0037] An example of a method for manufacturing a packaging container according to the present invention is described below. First, two laminates according to the present invention are prepared and stacked so that the heat-sealable layers face each other. Next, a sealing bar set to a predetermined temperature is applied to the surface of the base layer corresponding to the seal portion. The temperature when heat-sealing the laminate depends on the melting point Tm1 of the base layer, but from the viewpoint of sufficiently melting the heat-sealable layer and obtaining high seal strength, it is preferably 130°C or higher, more preferably 145°C or higher, and even more preferably 160°C or higher. The seal portion can be formed leaving one side for filling the contents. This results in a packaging container. The contents are then filled through the remaining open side, and the side is heat-sealed to obtain a packaging container filled with the contents. [Example]

[0038] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0039] <Resin used> Base resin A: Polybutylene terephthalate, melting point 225°C Base resin B: Polyethylene terephthalate, melting point 260°C Heat sealant resin C: Linear low-density polyethylene (LLDPE) melting point 107°C

[0040] The difference (Tm1-Tm2) between the melting point (Tm1) of the base resin A and the melting point (Tm2) of the heat sealant resin C is calculated to be 118°C (225-107=118), and the difference (Tm1-Tm2) between the melting point (Tm1) of the base resin B and the melting point (Tm2) of the heat sealant resin C is calculated to be 153°C (260-107=153).

[0041] <Extrusion test> Under the extrusion conditions shown in Table 1, a twin-screw kneading extruder ULTnano manufactured by Technovel Corporation was used to extrude a mixture of pellets of base resin A or B and pellets of heat sealant resin C as the raw resin. The change in resin pressure over time was measured using a sensor installed in the die, and the change in resin pressure over time in an extrusion test using only pellets of heat sealant resin C was used as a control for evaluation. The wire mesh was 120 mesh / 40 mesh from the upstream side. C1 to C5 in Table 1 indicate the heater setting temperatures for each section of the screw, from C1 near the hopper to C5 near the die. The die temperature is the molding temperature.

[0042] [Table 1]

[0043] (Control experiment) An extrusion test was conducted using pellets of heat sealant resin C alone under extrusion condition (1), and the change in resin pressure was recorded every 10 minutes for 40 minutes, as shown in Table 2. There was no particular increase in resin pressure.

[0044] Example 1 An extrusion test was carried out under extrusion condition (1) using a mixed resin prepared by pre-mixing pellets of base resin A and heat sealant resin C at a weight ratio of 20 / 80. The change in resin pressure was recorded for 40 minutes and is shown in Table 2. As with the control experiment, there was no particular increase in resin pressure.

[0045] (Comparative Example 1) An extrusion test was conducted under extrusion condition (1) using a mixed resin prepared by pre-mixing pellets of base resin B and heat sealant resin C at a weight ratio of 20 / 80. The change in resin pressure was recorded for 40 minutes and is shown in Table 2. Unlike the control experiment, after 30 minutes, as the resin pressure increased, surging occurred, causing the amount of resin extruded from the extruder to become unstable. This was thought to be due to the molding temperature of the mixed resin being too low for base resin B.

[0046] (Comparative Example 2) An extrusion test was conducted under extrusion condition (2) using a pre-mixed resin of base resin B and heat sealant resin C at a weight ratio of 20 / 80. Changes in resin pressure were recorded, but the test was interrupted before 10 minutes had elapsed due to a large amount of oily smoke emerging from the tip of the extruder. This was thought to be due to the molding temperature of the above mixed resin being too high for heat sealant resin C.

[0047] [Table 2]

[0048] The results of Example 1 and Comparative Example 1 show that when the difference between the melting point (Tm1) of base resin A and the melting point (Tm2) of heat sealant resin C, "Tm1 - Tm2," is 118°C, the mixed resin of base resin and heat sealant resin can be extruded under the same extrusion conditions as when the heat sealant resin is used alone. However, when "Tm1 - Tm2" is 153°C, it is difficult to extrude the mixed resin of base resin and heat sealant resin under the same extrusion conditions as when the heat sealant resin is used alone. [Explanation of symbols]

[0049] 1: Base material layer 2: Virgin polyolefin layer 3: Recycled layer 4: Heat seal layer 5: Adhesive layer 6: Vapor deposition layer 7: Colored virgin polyolefin layer 8: Recycled layer 9: Recycled white virgin polyolefin layer 10: Mixed recycled layer 10 11: Torso 12: Bottom 13: Side seal 14: Bottom seal 15: Top seal 16: Nozzle section 17:Cut line 18:Tip part 100: First form laminate 200: Second form laminate 300: Third form laminate 400: Fourth form laminate

Claims

1. At least the outer layer has a melting point Tm １ The base layer has a melting point Tm ２ A laminate comprising a heat seal layer having a temperature of 24° C.≦Tm １ -Tm ２ ≦152° C.

2. 2. The laminate according to claim 1, wherein the heat seal layer comprises at least three layers, the recycled layer being sandwiched between two layers of virgin polyolefin.

3. The recycled layer has a melting point Tm ３ and Tm ３ 3. The laminate of claim 2, wherein the temperature is ≦250° C.

4. 3. The laminate according to claim 1, wherein the substrate layer comprises a stretched film of polybutylene terephthalate.

5. 3. The laminate of claim 2, wherein the virgin polyolefin of said heat seal layer is polyethylene and all three layers in said heat seal layer are unoriented films.

6. 3. The laminate according to claim 1, further comprising a vapor-deposited layer using an inorganic substance or an inorganic oxide between the base layer and the heat seal layer.

7. 3. The laminate according to claim 2, wherein at least one of the two layers made of virgin polyolefin is a colored layer.

8. The laminate according to claim 1 or 2, wherein the base layer and the heat seal layer are laminated together using an adhesive.

9. 3. The laminate of claim 1 or 2, wherein the laminate is free of polyethylene terephthalate and polyamide.

10. A packaging container using the laminate according to claim 1 or 2.

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