Laminated body

Abstract

 The present invention addresses the problem of producing an environmentally friendly layered film comprising a base material film layer in which polyester resin recycled from PET bottles is used, and thereon, an inorganic thin film layer and a protective layer in this order, the layered film having excellent barrier properties and adhesiveness, and having excellent recyclability allowing the layered film and a sealant layer from a laminated layered body to be pulled apart readily. In order to solve the problem, the present invention has the following composition. The laminated layered body comprises a layered film having an inorganic thin film layer on one surface of a base material film, and a protective layer over the inorganic thin film layer, and a sealant layer layered on one surface of the layered film and is characterized in that the laminated layered body satisfies (a) to (d). (a) The base material film contains 10% by weight or more of a polyester resin recycled from PET bottles. (b) The protective layer of the layered film contains a urethane resin, and the surface free energy of the protective layer surface is 45 to 60 mN / m. (c) The laminated layered body has a lamination strength of 1.5 N / 15 mm or more, and after a 40 °C × 72 hours immersion in 1-methoxy-2-propanol, a lamination strength of 1.0 N / 15 mm or less. (d) The laminated layered body has a lamination strength of 1.5 N / 15 mm or more after a 90°C × 30 minutes boiling sterilization process.

Description

[Technical Field]

[0001] The present invention relates to a laminate film used in the packaging fields of foods, pharmaceuticals, industrial products, etc. More specifically, the present invention relates to a laminated film having a base film layer made of polyester resin recycled from PET bottles, a laminated film having an inorganic thin film layer and a protective layer in this order, and a sealant layer laminated thereon, the laminated film having excellent barrier properties and adhesiveness, and further having excellent recyclability because the film can be easily separated from the laminated film. [Background technology]

[0002] In recent years, regulations aimed at reducing the use of disposable plastics have been strengthened in Europe and other countries around the world. Behind this trend is growing international awareness of resource recycling and the worsening waste problems in emerging countries. As a result, there is a demand for environmentally friendly products that comply with the 3Rs (recycle, reuse, reduce) when it comes to plastic packaging materials for food, pharmaceuticals, etc.

[0003] The performance required for the aforementioned environmentally friendly packaging materials includes being made from recycled materials, having gas barrier properties that can block various gases and extend shelf life, and using materials that have a low environmental impact (for example, not using harmful organic solvents and using small amounts of materials).

[0004] A typical recycled material is polyester resin recycled from PET bottles, and there is a known technology for producing polyester film for body wrap labels that is less prone to static electricity problems without compromising productivity or quality from polyester resin derived from PET bottles, which has a low oligomer content (see, for example, Patent Document 1). Demand for such film applications is expected to expand due to future tightening of environmental regulations.

[0005] On the other hand, in food applications that require blocking various gases such as water vapor and oxygen, gas barrier laminates are generally used, in which a metal thin film made of aluminum or the like or an inorganic thin film made of an inorganic oxide such as silicon oxide or aluminum oxide is formed on the surface of a plastic substrate film. Among these, those formed with a thin film (inorganic thin film layer) of an inorganic oxide such as silicon oxide, aluminum oxide, or a mixture thereof are widely used because they do not require the use of aluminum foil and are transparent, allowing the contents to be confirmed.

[0006] Regarding the gas barrier film made of the aforementioned recycled material and inorganic thin film, a laminate film has been proposed that uses polyester resin recycled from PET bottles and has low heat shrinkage and small thickness unevenness, and when formed into a gas barrier laminate film with an inorganic thin film layer and a sealant layer, it exhibits good gas barrier properties (e.g., Patent Document 2). However, this conventional technology was insufficient for applications requiring higher barrier properties. Furthermore, there was no discussion of moist heat resistance or recyclability as a laminate.

[0007] As a means of maintaining barrier properties and adhesiveness even after moist heat treatment, it has been reported that a coating layer made of a water-soluble polymer containing an oxazoline group is provided between a substrate film and an inorganic thin film layer formed by, for example, a vapor deposition method (see, for example, Patent Document 3). Furthermore, attempts have been made to improve barrier performance by providing a protective layer with gas barrier properties on the inorganic thin film. For example, a method has been proposed in which a water-soluble polymer, an inorganic layered compound, and a metal alkoxide or a hydrolyzate thereof are coated on the inorganic thin film, and a composite of an inorganic material containing an inorganic layered compound and a water-soluble polymer is formed on the inorganic thin film by a sol-gel method; Examples include laminates coated with polyurethane (see, for example, Patent Document 4). By providing a coating layer, an inorganic thin film layer, and a protective layer in this way, it is possible to realize a gas barrier film that maintains its barrier properties and adhesiveness even after moist heat treatment.

[0008] However, when used as packaging bags for sterilization using moist heat treatment, in addition to barrier properties and adhesiveness, the film also requires heat resistance of the substrate itself, toughness (bag rupture resistance and pinhole resistance) depending on the contents, and high sealability. Therefore, gas barrier films alone cannot satisfy all of these requirements. Therefore, a two- or more-component structure is typically used, with a barrier polyester film on the outside of the bag, a polyamide film as an optional intermediate layer, and an olefin-based heat-sealable resin dry-laminated with an adhesive on the inside (contents side). These heterogeneous laminates have high adhesive strength sufficient for use, making them difficult to peel and separate when discarded after use. In this case, reuse as plastic (material recycling) is impossible, and traditionally, they have been disposed of by incineration as part of thermal recycling. However, with the recent growing awareness of environmental issues, there is a demand for laminates made from a single material, i.e., mono-material structures. For example, studies have been conducted to achieve both barrier and sealability in a single layer by applying an inorganic thin film to a polyester-based sealant (see, for example, Patent Document 5). However, with the current mono-material structure, it is difficult to meet all of the performance requirements for the sterilization bags mentioned above. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-91862 [Patent Document 2] Patent No. 6500629 [Patent Document 3] Patent No. 5560708 [Patent Document 4] Patent No. 4524463 [Patent Document 5] International Publication No. WO2019 / 187970 Summary of the Invention [Problem to be solved by the invention]

[0010] The above Patent Document 2 did not consider gas barrier properties or adhesive properties after severe moist heat treatment. The above Patent Documents 3 and 4 did not consider the recyclability of the laminated body after use. The above Patent Document 5 did not consider barrier properties or adhesive properties after moist heat treatment.

[0011] The present invention has been made in light of the problems with the prior art. That is, the object of the present invention is to provide a laminated product which is formed by laminating a sealant layer on an environmentally friendly laminated film having an inorganic thin film layer and a protective layer in that order on a base film layer made of polyester resin recycled from PET bottles, and which has excellent barrier properties and adhesiveness even after severe wet heat treatment, and which allows the laminated film to be easily separated, making it highly recyclable after use and disposal. [Means for solving the problem]

[0012] The inventors have discovered that by using a polyester resin derived from PET bottles, which has a low environmental impact, as a substrate and forming a structure with a specific barrier protection layer that is flexible and highly adhesive to the inorganic thin film layer, it is possible to improve the gas barrier performance before treatment and maintain the barrier properties and adhesion even after severe moist heat treatment. Furthermore, they have discovered that by utilizing the property of the protection layer that dissolves when immersed in a specific solvent, it is possible to easily peel the laminate film from the laminate, thereby completing the present invention.

[0013] That is, the present invention comprises the following configurations. (1) A laminated product comprising a base film having an inorganic thin film layer on at least one side thereof, a laminated film having a protective layer on the inorganic thin film layer, and a sealant layer on one side thereof, the laminated product being characterized in that the laminated product satisfies the following (a) to (d): (a) the base film contains 10% polyester resin recycled from PET bottles; Contains % by weight or more. (b) The protective layer of the laminated film contains a urethane resin, and the surface of the protective layer has a free surface area. The energy is 45 to 60 mN / m. (c) The laminate strength of the laminate is 1.5N / 15mm or more, and - The laminate strength after immersion in methoxy-2-propanol at 40°C for 72 hours is 1.0 N / 15 mm or less. (d) The laminate strength of the laminate after boiling sterilization at 90°C for 30 minutes is 1. 5N / 15mm or more. (2) The laminate according to (1), wherein the urethane resin contained in the protective layer contains an aromatic component or an aromatic aliphatic component as a constituent component. (3) A laminate according to either (1) or (2), which has a coating layer between the base film layer and the inorganic thin film layer, and the coating layer contains a resin having an oxazoline group or a carbodiimide group as a constituent component. (4) The laminate according to any one of (1) to (3), wherein the inorganic thin film layer is an aluminum oxide layer or a layer of a composite oxide of silicon oxide and aluminum oxide. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a laminated body that uses recycled materials and has excellent barrier properties and adhesiveness even after severe wet heat treatment, and it is also possible to provide a laminated body that has excellent recyclability and allows the laminated film to be easily peeled off from the laminated body. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in detail below. [Base film layer] In the present invention, as described below, a preferred embodiment uses recycled polyester resin recovered from PET bottles containing an isophthalic acid component as an acid component as the raw material for the substrate film. Therefore, the substrate film is a mixed resin of recycled polyester resin and virgin raw material, i.e., non-recycled resin, and the intrinsic viscosity of the resin constituting the film refers to the value obtained by measuring the intrinsic viscosity of the mixed resin constituting the film. The lower limit of the intrinsic viscosity of the resin constituting the film, as measured by the substrate film, is preferably 0.58 dL / g, more preferably 0.60 dL / g. If the intrinsic viscosity is less than 0.58 dL / g, many recycled resins from PET bottles have an intrinsic viscosity exceeding 0.68 dL / g. Reducing the viscosity when using such recycled resins to produce a film can result in thickness unevenness, which is undesirable. Furthermore, the film can become discolored, which is undesirable. The upper limit is preferably 0.70 dL / g, more preferably 0.68 dL / g. If the viscosity exceeds 0.70 dL / g, the resin becomes difficult to extrude from the extruder, which can reduce productivity, which is undesirable.

[0016] The lower limit of the thickness of the substrate film is preferably 8 μm, more preferably 10 μm. More preferably, it is 12 μm. If it is less than 8 μm, the strength of the film will be insufficient. The upper limit is preferably 200 μm, more preferably 50 μm. More preferably, it is 30 μm. If it exceeds 200 μm, it becomes too thick and processing becomes difficult. In addition, an increase in the thickness of the film is undesirable in terms of environmental load, and it is preferable to reduce the volume as much as possible.

[0017] The lower limit of the refractive index in the thickness direction of the substrate film is preferably 1.4930, more preferably 1.4940. If it is less than 1.4930, the orientation may be insufficient, and the laminate strength may not be obtained. The upper limit is preferably 1.4995, more preferably 1.4980. If it exceeds 1.4995, the surface orientation may be disrupted, and the mechanical properties may be insufficient, which is not preferable.

[0018] The lower limit of the heat shrinkage rate of the base film in the machine direction (sometimes referred to as MD) and the transverse direction (sometimes referred to as TD) when treated at 150°C for 30 minutes is preferably 0.1%, more preferably 0.3%. If it is less than 0.1%, the improvement effect will saturate and the film may become mechanically brittle, which is not preferable. The upper limit is preferably 3.0%, more preferably 2.5%. If it exceeds 3.0%, dimensional changes during processing such as printing may cause pitch deviation, which is not preferable. Furthermore, if it exceeds 3.0%, dimensional changes during processing such as printing may cause shrinkage in the width direction, which is not preferable.

[0019] As a raw material for the substrate film, it is preferable to use recycled polyester resin made from PET bottles containing an isophthalic acid component as an acid component. The crystallinity of the polyester used in PET bottles is controlled to improve the bottle's appearance, and as a result, polyesters containing 10 mol% or less of isophthalic acid are sometimes used. The inclusion of isophthalic acid disrupts the crystalline structure of the polyester, contributing to the flexibility of the substrate, and controlling this can create a surface that is easy to laminate an inorganic thin film on.

[0020] The lower limit of the amount of terephthalic acid component of all dicarboxylic acid components constituting the polyester resin contained in the base film is preferably 95.0 mol%, more preferably 96.0 mol%, even more preferably 96.5 mol%, and particularly preferably 97.0 mol%. A content of less than 95.0 mol% is not preferred because crystallinity decreases and the heat shrinkage rate may increase. Furthermore, the upper limit of the amount of terephthalic acid component of the polyester resin contained in the film is preferably 99.5 mol%, more preferably 99.0 mol%. Since recycled polyester resins made from PET bottles often contain dicarboxylic acid components other than terephthalic acid, such as isophthalic acid, it is not preferred for the terephthalic acid component constituting the polyester resin in the film to exceed 99.5 mol%, as this makes it difficult to produce polyester films with a high proportion of recycled resin.

[0021] In the present invention, controlling the amount of isophthalic acid component in the total dicarboxylic acid components constituting the polyester resin contained in the base film is important for imparting flexibility to exhibit barrier performance. The lower limit is preferably 0.5 mol%, more preferably 0.7 mol%, even more preferably 0.9 mol%, and particularly preferably 1.0 mol%. Some recycled polyester resins made of these materials contain a large amount of isophthalic acid components, so it is important that the isophthalic acid component constituting the polyester resin in the film is less than 0.5 mol%. This makes it difficult to produce a polyester film with a high proportion of recycled resin, which is undesirable. Furthermore, the flexibility of the surface is reduced, making the inorganic thin film layer more susceptible to stress loads when laminating the inorganic thin film layer, which may result in a deterioration in barrier performance. The upper limit of the amount of isophthalic acid component relative to all dicarboxylic acid components constituting the polyester resin contained in the film is preferably 5.0 mol%, more preferably 4.0 mol%, even more preferably 3.5 mol%, and particularly preferably 3.0 mol%. A content exceeding 5.0 mol% is undesirable because it reduces crystallinity and may increase the thermal shrinkage rate. Furthermore, if the substrate becomes too soft, the inorganic thin film may not be able to follow the changes, which may result in a deterioration in barrier performance. By setting the content of the isophthalic acid component within the above range, the softening effect of the substrate surface makes it easier for the inorganic thin film layer to deposit, resulting in the development of good barrier properties.

[0022] The upper limit of the intrinsic viscosity of the recycled resin from PET bottles is preferably 0.90 dL / g, more preferably 0.80 dL / g, even more preferably 0.77 dL / g, and particularly preferably 0.75 dL / g. If it exceeds 0.9 dL / g, it becomes difficult to extrude the resin from the extruder. This is not desirable as it can lead to a decrease in productivity.

[0023] The lower limit of the content of polyester resin recycled from PET bottles in the film is 10% by weight, preferably 50% by weight, more preferably 65% ​​by weight, and even more preferably 75% by weight. A content of less than 10% by weight results in a low content of recycled resin, which is undesirable in terms of contributing to environmental protection. Furthermore, the amount of isophthalic acid component decreases, which may prevent the development of the flexibility advantageous for laminating inorganic thin film layers. On the other hand, the upper limit of the content of polyester resin recycled from PET bottles is not particularly limited, but is preferably 95% by weight, more preferably 90% by weight, and even more preferably 85% by weight. A content exceeding 95% by weight is undesirable because it may be difficult to sufficiently add lubricants or additives such as inorganic particles to improve the film's functionality. Polyester resin recycled from PET bottles can also be used as a masterbatch (high-concentration resin) to add lubricants or additives such as inorganic particles to improve the film's functionality.

[0024] As the lubricant type, inorganic lubricants such as silica, calcium carbonate, and alumina are preferred, as well as organic lubricants, with silica and calcium carbonate being more preferred. These can provide transparency and lubricity. The average particle size of the lubricant particles is preferably within the range of 0.05 to 3.0 μm when measured with a Coulter counter.

[0025] The lower limit of the lubricant content in the base film is preferably 0.01% by weight, more preferably 0.015% by weight, and even more preferably 0.02% by weight. If it is less than 0.01% by weight, the lubrication The upper limit is preferably 1% by weight, more preferably 0.2% by weight, and even more preferably 0.1% by weight. If the content exceeds 1% by weight, the transparency may decrease, which is not preferable.

[0026] The method for producing the base film used in the laminated film of the present invention is not particularly limited, but the following production method is recommended, for example. The temperature setting for melting and extruding the resin in the extruder is important. The basic idea is as follows: (1) Polyester resin used in PET bottles Since the resin contains isophthalic acid, it is extruded at the lowest possible temperature to prevent deterioration, while (2) high temperatures and The reason is that it has a part that melts under high pressure. The inclusion of isophthalic acid components reduces the stereoregularity of the polyester, leading to a lower melting point. Therefore, extrusion at high temperatures causes a significant drop or deterioration in the melt viscosity due to heat, resulting in a decrease in mechanical strength and an increase in the amount of degraded foreign matter. Furthermore, simply lowering the extrusion temperature may not result in sufficient melt mixing, which can lead to problems such as an increase in thickness unevenness and foreign matter such as fish eyes. Based on the above, recommended manufacturing methods include, for example, using two extruders in tandem or increasing the pressure in the filter section. and a method in which a screw with a strong shearing force is used as part of the screw configuration.

[0027] The lower limit of the set temperature of the resin melting zone in the extruder (excluding the highest set temperature of the compression zone of the screw in the extruder) is preferably 270°C, and the upper limit is preferably 290°C. Extrusion is difficult, and temperatures above 290°C can cause resin deterioration, making this undesirable. stomach.

[0028] The lower limit of the maximum set temperature of the compression section of the screw in the extruder is preferably 295°C. The polyester resin used in plastic bottles often contains high-melting-point crystals (260°C to 290°C) for transparency reasons. In addition, additives and crystallization nucleating agents are added, which causes variations in the fine melting behavior within the resin material. If the temperature is below 295°C, these cannot be melted sufficiently. The upper limit of the maximum temperature setting for the compression section of the screw in the extruder is preferably 310°C. Temperatures above 310°C may cause deterioration of the resin, which is not desirable.

[0029] The lower limit of the time for the resin to pass through the highest set temperature zone of the compression section of the screw in the extruder is preferably 10 seconds, more preferably 15 seconds. If it is less than 10 seconds, the polyester resin used in the PET bottle will not be sufficiently melted, which is not preferred. The upper limit is preferably 60 seconds, more preferably 50 seconds. If it exceeds 60 seconds, the resin is more likely to deteriorate, which is not preferred. By setting the extruder within this range, it is possible to obtain a film with little thickness unevenness, foreign matter such as fisheyes, and coloration, while using a large amount of polyester resin recycled from PET bottles.

[0030] The molten resin is extruded onto a cooling roll in the form of a sheet and then biaxially stretched. Although simultaneous biaxial stretching may be used as the stretching method, sequential biaxial stretching is particularly preferred. This method makes it easier to achieve both the productivity and the quality required for the present invention.

[0031] In the present invention, the film stretching method is not particularly limited, but the following points are important. When stretching a resin having an intrinsic viscosity of 0.58 dl / g or more and containing an isophthalic acid component, the stretching ratio and temperature in the machine direction (MD) and transverse direction (TD) are important. If the MD stretching ratio and temperature are inappropriate, the stretching force will not be applied uniformly, resulting in insufficient molecular orientation, which may increase thickness unevenness and insufficient mechanical properties. Furthermore, in the subsequent TD stretching step, the film may break or experience extreme thickness unevenness. If the TD stretching ratio and temperature are inappropriate, the film may not be stretched uniformly, resulting in poor balance between the machine and transverse orientations and insufficient mechanical properties. Furthermore, if the film proceeds to the subsequent heat setting step with significant thickness unevenness or insufficient molecular chain orientation, uniform relaxation will not be achieved, leading to further thickness unevenness and insufficient mechanical properties. Therefore, it is basically recommended that in MD stretching, the temperature be controlled as described below to perform stretching in stages, and in TD stretching, stretching be performed at an appropriate temperature so as not to significantly impair the orientation balance. Although not limited to the following embodiment, an example will be described.

[0032] As a method for stretching in the machine direction (MD), a roll stretching method or an IR heating method is preferred.

[0033] The lower limit of the MD stretching temperature is preferably 100°C, more preferably 110°C, and even more preferably 120°C. If the temperature is less than 100°C, even if a polyester resin having an intrinsic viscosity of 0.58 dl / g or more is stretched and molecularly oriented in the machine direction, breakage of the film or extreme thickness defects may occur in the subsequent transverse stretching step, which is not preferable. The upper limit is preferably 140°C, and more preferably The temperature is preferably 135°C, and more preferably 130°C. If the temperature exceeds 140°C, the orientation of the molecular chains may deteriorate. This is not preferable because it may result in insufficient mechanical properties.

[0034] The lower limit of the MD stretching ratio is preferably 2.5 times, more preferably 3.5 times, and even more preferably 4 times. If it is less than 2.5 times, even if a polyester resin with an intrinsic viscosity of 0.58 dl / g or more is stretched and molecularly oriented in the machine direction, the film may break or have an extremely poor thickness in the subsequent transverse stretching step, which is not very preferable. The upper limit is preferably 5 times. More preferably, it is 4.8 times, and even more preferably, it is 4.5 times. The effect of improving thickness unevenness may become saturated, and there is little point in using it.

[0035] Although the MD stretching method may be the single-stage stretching described above, it is more preferable to divide the stretching into two or more stages, which allows for good stretching of polyester resins made from recycled resins containing isophthalic acid, which have a high intrinsic viscosity, and improves thickness unevenness, laminate strength, mechanical properties, etc.

[0036] The lower limit of the first-stage MD stretching temperature is preferably 110°C, more preferably 115°C. If the temperature is lower than 125°C, the film will not be sufficiently stretched in the longitudinal direction, resulting in poor flatness, which is undesirable. The upper limit of the first-stage MD stretching temperature is preferably 125°C, and more preferably 120°C. If the temperature exceeds 0°C, the molecular chain orientation becomes insufficient and the mechanical properties may deteriorate, which is not preferable.

[0037] The lower limit of the first-stage MD stretching ratio is preferably 1.1 times, and more preferably 1.3 times. When the stretching ratio is 2 or more, the polyester resin having an intrinsic viscosity of 0.58 dl / g or more can be finally stretched sufficiently in the longitudinal direction by the weak stretching in the first stage, and productivity can be improved. The upper limit of the MD stretching ratio in the first stage is preferably 2 times, and more preferably 1.6 times. When the stretching ratio exceeds 2 times, the molecular chain in the longitudinal direction is This is not preferable because the orientation of the film becomes too high, making it difficult to perform the second and subsequent stretching steps and resulting in a film with poor thickness uniformity.

[0038] The lower limit of the MD stretching temperature in the second stage (or final stage) is preferably 110°C, and more preferably The temperature is preferably 115°C. If the temperature is 110°C or higher, polyester resins having an intrinsic viscosity of 0.58 dl / g or higher can be sufficiently stretched longitudinally, and transverse stretching in the next step becomes possible, resulting in good thickness uniformity in the longitudinal and transverse directions. The upper limit is preferably 130°C, and more preferably 125°C. If the temperature exceeds 130°C, crystallization may occur. This is not preferable because it may accelerate the polymerization, make transverse stretching difficult, or cause large thickness variations.

[0039] The lower limit of the preferred second-stage (or final-stage) MD stretching ratio is preferably 2.1 times, The preferred ratio is 2.5 times. If the ratio is less than 2.1 times, even if a polyester resin having an intrinsic viscosity of 0.58 dl / g or more is stretched and molecularly oriented in the machine direction, the film may break or have an extremely poor thickness in the subsequent transverse stretching step, which is not very preferred. The upper limit is preferably 3.5 times. If the stretching ratio exceeds 3.5 times, the longitudinal orientation becomes too high, which is not preferable as it may become impossible to perform the second or subsequent stretching or the resulting film may have a large thickness unevenness.

[0040] The lower limit of the TD stretching temperature is preferably 110°C, more preferably 120°C, and even more preferably 125°C. If the temperature is less than 110°C, the stretching stress in the transverse direction increases, which may cause the film to break or the thickness unevenness to become extremely large, and this is not preferred. The upper limit is preferably 150°C, more preferably 145°C, and even more preferably 140°C. If the temperature exceeds 150°C, the orientation of the molecular chains does not increase, which may cause a decrease in mechanical properties, and this is not preferred.

[0041] The lower limit of the stretching ratio in the transverse direction (TD) is preferably 3.5 times, more preferably 3.9 times. If it is less than 3.5 times, the molecular orientation may be weak and the mechanical strength may be insufficient, which is not preferred. In addition, the orientation of the molecular chains in the longitudinal direction is large, and the longitudinal and lateral balance is poor, which results in large thickness unevenness, which is not very preferable. The upper limit is preferably 5.5 times, and more preferably The recommended thickness is 4.5 times or more. If the thickness exceeds 5.5 times, the material may break, which is not desirable.

[0042] To obtain a substrate film for use in the laminate film of the present invention, it is desirable to appropriately set the conditions for heat setting in the tenter following TD stretching and for cooling the film to room temperature. Polyester films containing recycled resins from PET bottles containing isophthalic acid have lower crystallinity, are more susceptible to micro-melting, and have lower mechanical strength than conventional polyethylene terephthalate films that do not contain isophthalic acid. Therefore, if the film is suddenly exposed to high temperatures under tension after stretching or if it is suddenly cooled under tension after high-temperature heat setting, the inevitable temperature difference across the film's width disrupts the tension balance in the width direction, resulting in thickness unevenness and poor mechanical properties. On the other hand, attempting to address this phenomenon by lowering the heat setting temperature may result in insufficient laminate strength. In the present invention, it is recommended that the film be subjected to heat setting 1 at a slightly lower temperature, heat setting 2 at a sufficiently higher temperature (or heat setting 3, if necessary), followed by a slow cooling step to cool the film to room temperature. However, this method is not limited to this, and examples thereof include a method of controlling the film tension in accordance with the hot air speed in the tenter and the temperature of each zone, a method of performing heat treatment at a relatively low temperature in an oven with a sufficient length after stretching, and a method of relaxing the film with a heated roll after heat setting.

[0043] As an example, a method of controlling the temperature of a tenter is shown below: Heat fixation zones 1, 2, and 3 are arranged in this order from the upstream side in the film flow direction in the heat fixation zone of the tenter.

[0044] The lower limit of the temperature for heat setting 1 is preferably 160°C, more preferably 170°C. If the temperature is less than this, the final heat shrinkage rate will be large, which may cause misalignment or shrinkage during processing, which is not preferable. The upper limit is preferably 215°C, and more preferably 210°C. If the temperature exceeds 215°C, high temperatures will be applied to the film suddenly, which will increase thickness unevenness. This is not desirable as it may cause damage or breakage.

[0045] The lower limit of the time for heat setting 1 is preferably 0.5 seconds, more preferably 2 seconds. If the time is less than 10 seconds, the temperature of the film may not rise sufficiently. The upper limit is preferably 10 seconds, and more preferably 8 seconds. If the time exceeds 10 seconds, the productivity may decrease, which is not preferable. stomach.

[0046] The lower limit of the temperature for heat setting 2 is preferably 220°C, more preferably 227°C. If the temperature is less than 240°C, the thermal shrinkage rate will be large, which may cause displacement or shrinkage during processing, which is not very preferable. The upper limit is preferably 240°C, more preferably 237°C. This is not desirable because the film may melt, or even if it does not melt, it may become brittle.

[0047] The lower limit of the time for heat setting 2 is preferably 0.5 seconds, more preferably 3 seconds. If the time is less than 10 seconds, the film may be easily broken during heat setting, which is not preferable. The upper limit is preferably 10 seconds, and more preferably 8 seconds. If the time is more than 10 seconds, sagging and the like may occur. This may cause unevenness in thickness, which is not preferable.

[0048] If necessary, the lower limit of the temperature when the heat fixation 3 is performed is preferably 205°C, and more preferably The temperature is preferably 220°C. If the temperature is less than 205°C, the heat shrinkage rate will be large, which may cause displacement or shrinkage during processing, and is therefore not very preferable. The upper limit is preferably 240°C, and more preferably 237°C. If the temperature exceeds 240°C, the film will melt, and even if it does not melt, it will become brittle. This can be undesirable.

[0049] If necessary, the lower limit of the time for providing the heat fixation 3 is preferably 0.5 seconds, and more preferably Preferably, it is 3 seconds. If it is less than 0.5 seconds, breakage may occur easily during heat setting, which is not preferable. The upper limit is preferably 10 seconds, and more preferably 8 seconds. If it exceeds 10 seconds, sagging may occur, resulting in thickness unevenness, which is not preferable. .

[0050] TD relaxation can be carried out at any point during heat setting. The lower limit is preferably 0.5%. It is more preferably 3%. If it is less than 0.5%, the thermal shrinkage rate in the lateral direction in particular becomes large, which may lead to displacement or shrinkage during processing, which is not preferred. The upper limit is preferably 10%, more preferably 8%. If it exceeds 10%, sagging may occur, which may lead to thickness unevenness, which is not preferred.

[0051] The lower limit of the slow cooling temperature after TD heat setting is preferably 90° C., more preferably 100° C. If the temperature is lower than 90° C., the film contains isophthalic acid, and therefore, the film may be cooled due to a sudden temperature change. This is not preferable because it may cause uneven thickness or breakage due to shrinkage caused by the slow cooling. The upper limit of the slow cooling temperature is preferably 150°C, more preferably 140°C. If the temperature exceeds this range, sufficient cooling effect may not be obtained, which is not desirable.

[0052] The lower limit of the slow cooling time after heat setting is preferably 2 seconds, more preferably 4 seconds. If the cooling time is less than 20 seconds, a sufficient cooling effect may not be obtained, which is not preferable. The upper limit is preferably 20 seconds, and more preferably 15 seconds. If the cooling time exceeds 20 seconds, it is likely to be disadvantageous in terms of productivity, which is not preferable.

[0053] The upper limit of the haze per thickness of the base film layer in the present invention is preferably 0.66% / μm, more preferably 0.60% / μm, and even more preferably 0.53% / μm. When printing is performed on a base film layer having a haze of 0.66% / μm or less, the quality of the printed characters and images is improved.

[0054] Furthermore, the base film layer in the present invention may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, or surface roughening treatment, and may also be subjected to known anchor coating treatment, printing, decoration, etc., as long as the object of the present invention is not impaired.

[0055] Furthermore, a layer of another material may be laminated on the base film layer of the present invention, and as a method for this, the layer may be laminated after the base film layer is produced, or during film formation.

[0056] [Inorganic thin film layer] The gas barrier laminate film of the present invention has an inorganic thin film layer on the surface of the base film layer. The inorganic thin film layer is a thin film made of a metal or inorganic oxide. There are no particular limitations on the material forming the inorganic thin film layer as long as it can be formed into a thin film. However, from the viewpoint of gas barrier properties, inorganic oxides such as silicon oxide (silica), aluminum oxide (alumina), and a mixture of silicon oxide and aluminum oxide are preferred. In this composite oxide, the mixing ratio of silicon oxide to aluminum oxide is preferably in the range of 20 to 70% by mass of Al relative to the mass of the metal. If the Al concentration is less than 20% by mass, the water vapor barrier properties may be reduced. On the other hand, if the Al concentration exceeds 70% by mass, the inorganic thin film layer tends to become hard, which may result in destruction of the film during secondary processing such as printing or lamination, resulting in reduced gas barrier properties. Furthermore, if the Al concentration is 100% by mass, the water vapor barrier performance is good, but the surface tends to be smooth due to the use of a single material, resulting in poor slipperiness and the likelihood of processing defects (wrinkles, acne, etc.). The silicon oxide referred to here is a variety of silicon oxides such as SiO and SiO2, or a mixture thereof, and the aluminum oxide is a variety of aluminum oxides such as AlO and Al2O3, or a mixture thereof.

[0057] The inorganic thin film layer has a thickness of usually 1 to 100 nm, preferably 5 to 50 nm. If the thickness of the inorganic thin film layer is less than 1 nm, it may be difficult to obtain satisfactory gas barrier properties. On the other hand, even if the thickness is excessively greater than 100 nm, the corresponding improvement in gas barrier properties cannot be obtained and is actually disadvantageous in terms of flex resistance and production costs.

[0058] The method for forming the inorganic thin film layer is not particularly limited, and any known deposition method, such as physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, or chemical vapor deposition (CVD), may be appropriately employed. A typical method for forming an inorganic thin film layer will be described below, taking silicon oxide / aluminum oxide-based thin films as an example. For example, when using vacuum deposition, a mixture of SiO2 and Al2O3 or a mixture of SiO2 and Al is preferably used as the deposition source. These deposition sources are typically particles, and the particle size is preferably large enough to prevent pressure changes during deposition, with a preferred particle diameter of 1 mm to 5 mm. Heating methods include resistance heating, high-frequency induction heating, electron beam heating, and laser heating. Reactive deposition can also be employed, using reactive gases such as oxygen, nitrogen, hydrogen, argon, carbon dioxide, and water vapor, or by adding ozone or ion-assisted deposition. Furthermore, the deposition conditions can be freely modified by applying a bias to the deposition target (the laminated film to be deposited) or by heating or cooling the deposition target. The deposition material, reactive gas, bias of the deposition target, heating / cooling, etc. can be changed in the same way when the sputtering method or the CVD method is adopted.

[0059] [Coating layer] The laminate film of the present invention may have a coating layer between the base film layer and the inorganic thin film layer to ensure gas barrier properties and laminate strength after retort treatment. Resin compositions used for the coating layer between the base film layer and the inorganic thin film layer include resins such as urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, and polybutadiene-based resins to which curing agents such as epoxy-based, isocyanate-based, melamine-based, oxazoline-based, and carbodiimide-based curing agents have been added. The resin compositions used for these coating layers preferably contain a silane coupling agent having at least one organic functional group. Examples of the organic functional group include an alkoxy group, an amino group, an epoxy group, and an isocyanate group. The addition of the silane coupling agent further improves the laminate strength after retort treatment.

[0060] Among the resin compositions used for the coating layer, it is preferable to use a resin containing an oxazoline group or a carbodiimide group, and it is more preferable to use a mixture of an acrylic resin and a urethane resin in addition to these. These functional groups have high affinity with inorganic thin films and can react with oxygen-deficient portions of inorganic oxides or metal hydroxides generated during the formation of the inorganic thin film layer, thereby exhibiting strong adhesion to the inorganic thin film layer. Furthermore, unreacted functional groups present in the coating layer can react with carboxylic acid terminals generated by hydrolysis of the base film layer and the coating layer to form crosslinks.

[0061] In the present invention, the coating weight of the coating layer is 0.010 to 0.200 (g / m 2 ) is preferable. This allows the coating layer to be controlled uniformly, resulting in dense deposition of the inorganic thin film layer. In addition, the cohesive force within the coating layer is improved, and the adhesion between the substrate film, coating layer, and inorganic thin film layer is also increased, thereby improving the water-resistant adhesion of the coating layer. The coating layer preferably has a deposition weight of 0.015 (g / m 2 ) or more, more preferably 0.020 (g / m 2 ) or more, more preferably 0.025 (g / m 2 ) or more, and preferably 0.190 (g / m 2 ) or less, more preferably 0.180 (g / m 2 ) or less, more preferably 0.170 (g / m 2 ) or less. The coating layer adhesion weight is 0.200 (g / m 2 ), the cohesive force inside the coating layer becomes insufficient, and good adhesion may not be achieved. In addition, the uniformity of the coating layer also decreases, which may cause defects in the inorganic thin film layer and reduce the gas barrier properties. Furthermore, if the coating layer is too thick, the flexibility effect of the substrate is reduced, leading to a deterioration in the gas barrier properties. Moreover, the manufacturing cost increases, which is economically disadvantageous. On the other hand, if the coating layer thickness is more than 0.010 (g / m 2 If the thickness is less than 1 / 2 mm, the substrate cannot be sufficiently covered, and there is a risk that sufficient gas barrier properties and interlayer adhesion cannot be obtained.

[0062] The method for forming the coating layer is not particularly limited, and conventionally known methods such as coating methods can be used. Among coating methods, offline coating and in-line coating are preferred. For example, in the case of in-line coating, which is performed in the process of producing a base film layer, the conditions for drying and heat treatment during coating depend on the coating thickness and the conditions of the equipment, but it is preferable to feed the film to a stretching process in the perpendicular direction immediately after coating and dry it in a preheating zone or stretching zone of the stretching process. In such cases, it is usually preferable to use a temperature of about 50 to 250°C. Examples of the solvent to be used when using the coating method include aromatic solvents such as benzene and toluene; alcohol solvents such as methanol and ethanol; ketone solvents such as acetone and methyl ethyl ketone; ester solvents such as ethyl acetate and butyl acetate; and polyhydric alcohol derivatives such as ethylene glycol monomethyl ether.

[0063] [Protective layer] In the present invention, a protective layer is provided on the inorganic thin film layer. The metal oxide layer is not a completely dense film, but has minute defects scattered thereon. By forming a protective layer by coating the metal oxide layer with a specific resin composition for the protective layer, which will be described later, the resin in the resin composition for the protective layer penetrates into the defects in the metal oxide layer, resulting in stable gas barrier properties. In addition, by using a material with gas barrier properties for the protective layer itself, the gas barrier performance of the laminate film is also greatly improved. Furthermore, in the present invention, it has been discovered that the laminate can be easily separated after use by utilizing the fact that the protective layer easily swells in specific solvents.

[0064] The resin composition used in the protective layer formed on the inorganic thin film layer of the laminate film of the present invention is a resin having a urethane skeleton. The inclusion of a urethane resin is preferable because, in addition to the barrier performance due to the high cohesiveness of the urethane bond itself, the polar groups interact with the inorganic thin film layer, and the presence of amorphous portions provides flexibility, thereby reducing damage to the inorganic thin film layer even when subjected to bending loads. Furthermore, due to the solubility parameter of the urethane resin, it has the property of swelling and solubility in alcohol-based solvents, allowing the laminate film to be easily peeled from the laminate using alcohol-based solvents, which are inexpensive organic solvents with relatively low environmental impact. The peeled films become single materials, making them recyclable.

[0065] The surface free energy of the protective layer in the present invention is preferably 45 to 60 mN / m, more preferably 46 to 59 mN / m, and even more preferably 47 to 58 mN / m or more. By setting the surface free energy within the above range, it is possible to achieve both good gas barrier properties and adhesion before and after moist heat treatment such as boiling, as well as the ability of the protective layer to easily swell and be easily peeled off when immersed in alcohol. If the surface free energy is 45 mN / m or less, the protective layer will be hydrophobic, improving moist heat resistance but reducing alcohol swelling resistance. On the other hand, if the surface free energy is 60 mN / m or more, the alcohol swelling resistance will be excellent, but moist heat resistance may be reduced.

[0066] (urethane resin) From the perspective of improving gas barrier properties, it is more preferable to use a urethane resin containing an aromatic or araliphatic diisocyanate component as its main constituent. Among these, it is particularly preferable to use a tolylene diisocyanate or metaxylylene diisocyanate component. By using such a resin, the cohesive strength of the urethane bond can be further enhanced by the stacking effect between aromatic rings, resulting in excellent gas barrier properties. Furthermore, the cohesive strength of the urethane bond is formed by hydrogen bonds, and exposure to highly permeable alcohol-based solvents can lead to dissociation and swelling. As a result, the adhesive strength of the protective layer decreases, allowing for easy peeling of the film via the protective layer. Examples of alcohol-based solvents include ethanol, 2-propanol, and 1-methoxy-2-propanol. These solvents have a solubility parameter (SP) of 9 to 13, which is close to the SP of general urethane resins (approximately 10), making them easily miscible and swollen. 1-Methoxy-2-propanol is particularly suitable, as its SP value is approximately 10, similar to that of urethane.

[0067] In the present invention, the proportion of aromatic or araliphatic diisocyanate in the urethane resin is preferably 50 mol % or more (50 to 100 mol %) based on 100 mol % of the isocyanate component. The total proportion of aromatic or araliphatic diisocyanate is preferably 60 to 100 mol %, more preferably 70 to 100 mol %, and even more preferably 80 to 100 mol %. If the total proportion of aromatic or araliphatic diisocyanate is less than 50 mol %, good gas barrier properties may not be obtained.

[0068] From the viewpoint of improving barrier properties due to cohesive strength, the urethane resin used in the present invention preferably has a glass transition temperature (Tg) of 10°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher. Furthermore, in order to improve adhesion strength and swelling properties in alcohol-based solvents, the glass transition temperature (Tg) is preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. If the Tg is outside the above range, it will be impossible to achieve both cohesive strength and flexibility / swellability, which may result in poor barrier properties or adhesion, and furthermore, easy peeling upon immersion in alcohol-based solvents will not be achieved.

[0069] In the present invention, the amount of the protective layer is set to 0.10 to 0.40 (g / m 2 ) is preferable. This allows the protective layer to be uniformly controlled during coating, resulting in a film with fewer coating irregularities and defects. In addition, the cohesive force of the protective layer itself is improved, and the adhesion between the inorganic thin film layer and the protective layer is also strengthened. The amount of adhesion of the protective layer is preferably 0.13 (g / m 2 ) or more, more preferably 0.16 (g / m 2 ) or more, more preferably 0.19 (g / m 2 ) or more, and preferably 0.37 (g / m 2 ) or less, more preferably 0.34 (g / m 2 ) or less, more preferably 0.31 (g / m 2 ) or less. The protective layer adhesion is 0.400 (g / m 2 ), the gas barrier properties improve, but the cohesive force inside the protective layer becomes insufficient and the uniformity of the protective layer also decreases, which can result in unevenness or defects in the coat appearance and insufficient gas barrier properties and adhesiveness. On the other hand, if the thickness of the protective layer is more than 0.10 (g / m 2 If the thickness is less than 1 / 2 mm, sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0070] The method for applying the resin composition for the protective layer is not particularly limited as long as it is a method that can apply the resin composition for the protective layer to the surface of a film to form a layer. For example, a conventional coating method such as gravure coating, reverse roll coating, wire bar coating, or die coating can be used.

[0071] When forming a protective layer, it is preferable to apply a protective layer resin composition and then heat-dry it. The drying temperature is preferably 110 to 190°C, more preferably 130 to 185°C, and even more preferably 150 to 180°C. Drying temperatures below 110°C can result in insufficient drying of the protective layer, or in a slow progress in film formation of the protective layer, resulting in reduced cohesive strength and water-resistant adhesion, and consequently reduced barrier properties and hand-tearability. On the other hand, drying temperatures above 190°C can result in excessive heat being applied to the film, making it brittle and reducing puncture strength, or shrinking and impairing processability. Drying at 150°C or higher, preferably 160°C or higher, can effectively promote film formation of the protective layer, increasing the adhesive area between the resin of the protective layer and the inorganic thin film layer and improving water-resistant adhesion. It is particularly preferable to first volatilize the solvent at a relatively low temperature of 90 to 110°C immediately after application, and then dry at 150°C or higher, as this results in a uniform film. In addition to drying, additional heat treatment at a temperature as low as possible is also effective in accelerating the formation of the protective layer.

[0072] [Packaging materials] The laminate of the present invention requires the use of a heat-sealable resin layer called a sealant layer. The heat-sealable resin layer is usually provided on an inorganic thin film layer, but may also be provided on the outside of the base film layer (the surface opposite to the surface on which the coating layer is formed). The heat-sealable resin layer is usually formed by extrusion lamination or dry lamination. The thermoplastic polymer forming the heat-sealable resin layer may be any polymer that can sufficiently exhibit sealant adhesion, and examples of such polymers that can be used include polyethylene resins such as HDPE, LDPE, and LLDPE, polypropylene resins, ethylene-vinyl acetate copolymers, ethylene-α-olefin random copolymers, and ionomer resins. Among these, LLDPE or polypropylene resins are particularly preferred because of their high versatility in terms of durability, seal strength, price, etc. The sealant layer The thickness is preferably 20 to 100 μm, more preferably 30 to 90 μm, and even more preferably 40 to 80 μm. If the thickness is thinner than 20 μm, sufficient seal strength may not be obtained, and the bag may lose its stiffness and become difficult to handle. On the other hand, if the thickness exceeds 100 μm, the bag may become too stiff, making it difficult to handle as a bag, and the price may also become high.

[0073] [Adhesive layer] The adhesive layer used in the present invention can be a general-purpose laminating adhesive. For example, solvent-free, aqueous, or hot-melt adhesives based on poly(ester)urethane, polyester, polyamide, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, or casein can be used. Among these, urethane or polyester adhesives are preferred in terms of their moist heat resistance, which can withstand retort treatment, and their flexibility, which can accommodate dimensional changes in each substrate. The adhesive layer can be applied by, for example, direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, fountain coating, or other methods. Since sufficient adhesion is maintained even after moist heat treatment, the coating weight after drying should be 1 to 8 g / m. 2 More preferably, it is 2 to 7 g / m 2 , and more preferably 3 to 6 g / m 2 The coating amount is 1g / m 2 If the coating weight is less than 8 g / m², it becomes difficult to bond the entire surface, and the adhesive strength decreases. If the coating weight is more than 8 g / m², it takes a long time for the film to completely harden, and unreacted material is likely to remain, resulting in a decrease in adhesive strength.

[0074] Furthermore, the laminate film of the present invention may have at least one printed layer or other plastic substrate and / or paper substrate layer laminated between or on the outside of the inorganic thin film layer or substrate film layer and the heat-sealable resin layer.

[0075] As the printing ink for forming the printing layer, aqueous and solvent-based resin-containing printing inks are preferably used. Examples of resins used in printing inks include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. The printing ink may contain known additives such as antistatic agents, light-blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, crosslinking agents, anti-blocking agents, and antioxidants. The printing method for forming the printing layer is not particularly limited, and known printing methods such as offset printing, gravure printing, and screen printing can be used. To dry the solvent after printing, known drying methods such as hot air drying, heat roll drying, and infrared drying can be used.

[0076] The laminate of the present invention has an oxygen permeability of 20 ml / m under conditions of 23°C x 65% RH before and after boiling at 90°C for 30 minutes. 2 In order to achieve good gas barrier properties, it is preferable that the applied amount of the inorganic thin film layer component is 15 ml / m or less. 2 ·d·MPa or less, preferably 10ml / m 2 If the oxygen permeability exceeds 20 ml / m²·d·MPa, it becomes difficult to use the product in applications that require high gas barrier properties. On the other hand, if the oxygen permeability is 1 ml / m² both before and after retort treatment, 2 If the oxygen permeability is less than 1 ml / m, the barrier performance will be excellent, but the residual solvent will not easily permeate to the outside of the bag, which is undesirable as it may result in a relatively increased amount of migration to the contents. 2 ·d·MPa or more.

[0077] The laminate of the present invention preferably has a laminate strength of 1.5 N / 15 mm or more under conditions of 23°C x 65% RH before and after boiling at 90°C for 30 minutes, more preferably 1.8 N / 15 mm or more, and even more preferably 2.0 N / 15 mm or more. If the laminate strength is less than 1.5 N / 15 mm, peeling may occur due to bending load or liquid contents, resulting in deterioration of barrier properties or leakage of contents. Furthermore, hand tearability may also be impaired.

[0078] The laminate of the present invention preferably has a laminate strength of 1.0 N / 15 mm or less, more preferably 0.9 N / 15 mm or less, and even more preferably 0.8 N / 15 mm or less, after immersion in 1-methoxy-2-propanol, an alcoholic solvent, at 40°C for 72 hours. If the laminate strength exceeds 1.0 N / 15 mm, it becomes difficult to easily peel the laminate from the laminate, which may result in poor recyclability. Furthermore, by increasing the immersion temperature or lengthening the immersion time, a further decrease in laminate strength can be expected, making peeling easier.

[0079] The temperature during solvent immersion in the present invention is preferably 10 to 60°C, more preferably 15 to 55°C, and even more preferably 20 to 50°C. If the temperature is lower than 10°C, the solvent may not penetrate the laminate easily, and peeling may not be easy. On the other hand, if the temperature is higher than 60°C, the evaporation of 1-methoxy-2-propanol may be accelerated, and the immersion liquid may be reduced, which is undesirable from the standpoints of economy and safety.

[0080] The humidity during solvent immersion in the present invention is not particularly limited, but in a general environment, it is preferably 10 to 80% RH, more preferably 15 to 75% RH, and even more preferably 20 to 70% RH. To create a humidity environment of less than 10% RH or more than 80% RH, humidity control equipment is required, which may increase management and processing costs.

[0081] In the present invention, the preferred solvent immersion time is 12 to 72 hours, more preferably 24 to 60 hours, and even more preferably 36 to 48 hours. If the immersion time is shorter than 12 hours, the solvent may not fully penetrate the laminate, making it difficult to peel. On the other hand, if the immersion time exceeds 72 hours, the treatment time becomes too long, and the method may not be considered effective in terms of efficiency.

[0082] In the laminate of the present invention, the ratio of recycled PET resin to the total weight of the laminate (recycle ratio) The percentage of the total surface area (hereinafter referred to as the "surface area") is preferably 3% or more, more preferably 5% or more, and even more preferably If the recycled content is less than 3%, the recycled resin content is low and the film may not be environmentally friendly.

[0083] As described above, the laminate of the present invention uses recycled materials, yet has excellent barrier properties and adhesiveness even after severe wet heat treatment, and can provide a film with excellent recyclability that allows the laminate film to be easily peeled off from the laminate. [Example]

[0084] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. The films were evaluated by the following measurement methods. Hereinafter, Example 6 will be read as Reference Example 1, and Example 8 will be read as Reference Example 2, respectively.

[0085] (1) Intrinsic viscosity (IV) of the raw resin and the resin that makes up the film The sample was dried in a vacuum at 130°C overnight, then crushed or cut, and 80 mg of the crushed sample was precisely weighed and dissolved in a mixed solution of phenol / tetrachloroethane = 60 / 40 (volume ratio) at 80°C for 30 minutes by heating. After dissolving by heating at 80°C, the sample was cooled to room temperature, and the mixed solvent prepared in the above ratio was added to a measuring flask to make 20 ml, after which the viscosity was measured at 30°C (unit: dl / g). An Ostwald viscometer was used to measure the intrinsic viscosity.

[0086] (2) Content of terephthalic acid and isophthalic acid components contained in the raw polyester and the polyester that constitutes the film A sample solution was prepared by dissolving the raw polyester resin or polyester film in a solvent containing a 10:1 (volume ratio) mixture of chloroform D (manufactured by Eurisop) and trifluoroacetic acid D1 (manufactured by Eurisop). The sample solution was then subjected to NMR measurement of the protons in the sample solution using an NMR device (Varian GEMINI-200 nuclear magnetic resonance analyzer) at a temperature of 23°C and an accumulation count of 64. In the NMR measurement, the peak intensity of a specific proton was calculated, and the content (mol%) of terephthalic acid and isophthalic acid components in 100 mol% of the acid component was calculated.

[0087] (3) Thickness of the base film Measurement was carried out using a dial gauge in accordance with JIS K7130-1999 Method A.

[0088] (4) Composition and thickness of inorganic thin film layer The film thickness composition of the laminated films (after thin film lamination) obtained in the examples and comparative examples was measured using a fluorescent X-ray analyzer ("ZSX100e" manufactured by Rigaku Corporation) based on a previously prepared calibration curve. The excitation X-ray tube conditions were 50 kV and 70 mA.

[0089] (5) Amount of protective layer attached In each example and comparative example, each laminated film obtained at the stage of laminating a protective layer on a base film was used as a sample, and a 100 mm × 100 mm test piece was cut out from this sample, and the protective layer was wiped off with dimethylformamide. The amount of adhesion was calculated from the change in mass of the film before and after wiping.

[0090] (6) Surface free energy of the protective layer For the laminated films obtained in the examples and comparative examples, water and methylene iodide were dropped onto the films using a contact angle meter (model: CAM200, sold by Altec Alto Co., Ltd., manufactured by KSV Instruments, Finland), and the contact angles were measured. The contact angle was read 5 seconds after the water droplets were dropped onto the films. FAMAS (Kyowa Interface Science Co., Ltd.) was used as the analysis software. Detailed conditions for measurement and analysis are shown below. Temperature and humidity: 23℃, 65% Measurement method: Droplet method (θ / 2 method) Droplet size: 5.0 μL (water), 1.5 μL (methylene iodide) Needle size: 22G, inner diameter 0.4mm Next, using the contact angle θ obtained, the surface free energy was calculated by the Owens-Wendt method. Calculated. First, the surface free energy γ i is the non-polar dispersion force component, γ d and polar hydrogen-bonding components, gamma h Assume that the following equation holds at the AB interface, which is assumed to consist of: gamma i =γ i d +γ i h Next, the interfacial tension γ between A and B AB It is assumed that the following equation of the extended Fowkes model (which expresses the contribution of the decreasing interfacial tension in terms of the contributions of the dispersion force and polar force of intermolecular forces) holds true for gamma AB =γ A +γ B -2(γ A d gamma B d ) 1 / 2 -2(γ A h gamma B h ) 1 / 2 Regarding this, when combining with Young's equation for the case of liquid L and solid S, the following equation holds: do. γL(1+cosθ)=2(γ A d gamma B d ) 1 / 2 +2(γ A h gamma B h ) 1 / 2 The surface free energy of the solid was calculated by measuring theta using liquids (water and methylene iodide) whose surface free energy components are known, and solving simultaneous equations from the measured values.

[0091] [Preparation of laminate a] A polyurethane adhesive (TM569 manufactured by Toyo-Morton Co., Ltd.) was applied to the protective layer surface of the laminated film obtained in the Examples and Comparative Examples so that the thickness after drying treatment at 80°C would be 3 μm. A linear low-density polyethylene film (L4102 manufactured by Toyobo Co., Ltd.; thickness 40 μm; referred to as LL) was then dry-laminated on a metal roll heated to 60°C, and aging was carried out at 40°C for 4 days to obtain a laminate gas barrier laminate for evaluation (hereinafter sometimes referred to as "laminate a").

[0092] [Preparation of laminated body b] A polyurethane adhesive (TM569 manufactured by Toyo-Morton Co., Ltd.) was applied to the protective layer surface of the laminated film obtained in the Examples and Comparative Examples so that the thickness after drying treatment at 80°C would be 3 μm. An unstretched polypropylene film (P1176 manufactured by Toyobo Co., Ltd.; thickness 70 μm; referred to as CPP) was then dry-laminated on a metal roll heated to 60°C, and aging was carried out at 40°C for 4 days to obtain a laminated gas barrier laminate for evaluation (hereinafter sometimes referred to as "laminate laminate b").

[0093] (7) Evaluation method for oxygen permeability Regarding the laminated body prepared in the above [Preparation of laminated body], According to the 7126 B method, oxygen permeability under normal conditions was measured using an oxygen permeability measuring device (MOCON's "OX-TRAN (registered trademark) 1 / 50") under an atmosphere of 23°C and 65% RH. The oxygen permeability measurement was performed in the direction in which oxygen permeated from the substrate film side of the laminate to the heat-sealable resin layer side. The laminate prepared in the above "Preparation of Laminated Laminate" section was subjected to a moist heat treatment by being kept in hot water at 90°C for 30 minutes, and then dried at 40°C for 1 day (24 hours). The resulting moist heat-treated laminate was then measured for oxygen permeability (after boiling) in the same manner as above.

[0094] (8) Evaluation method for lamination strength before and after boiling The laminated body prepared above was cut into a width of 15 mm and a length of 200 mm to prepare a test piece, and the laminate strength (before treatment) was measured using a Tensilon universal testing machine ("Tensilon UMT-II-500" manufactured by Toyo Baldwin Co., Ltd.) under conditions of a temperature of 23°C and a relative humidity of 65%. The laminate strength was measured at a tensile speed of 200 mm / min, and the strength was measured when the laminated film layer and the heat-sealable resin layer of each laminated film obtained in the examples and comparative examples were peeled at a peel angle of 90 degrees. On the other hand, the laminated body prepared above was subjected to a boiling treatment in which it was kept in pressurized hot water at a temperature of 90°C for 30 minutes, and then test pieces were immediately cut out from the resulting laminated body after retort treatment in the same manner as above, and the laminate strength (after boiling treatment) was measured in the same manner as above.

[0095] (9) Evaluation method for laminate strength after immersion in 1-methoxy-2-propanol The laminated body prepared as described above was immersed in 1-methoxy-2-propanol (Wako Pharmaceuticals) under an environment of either 23°C x 65% RH or 40°C x 15% RH for 24 or 48 hours, and then test pieces were immediately cut out from the resulting laminated body in the same manner as described above, and the laminate strength (after immersion) was measured in the same manner as described above.

[0096] (10) Evaluation of peelability after immersion in 1-methoxy-2-propanol When the laminated body immersed under the conditions of (9) above was peeled off, the laminated body that could be easily peeled off the laminated film and sealant by hand was marked with a ◯, and the laminated body that could not be peeled off was marked with an X.

[0097] (11) Calculation of recycling rate For the laminate produced above, the specific gravity of the polyester laminate film was set to 1.4, the specific gravity of the sealant linear low-density polyethylene film was set to 0.92, and the specific gravity of the unstretched polypropylene film was set to 0.91, and the amount of recycled PET resin used relative to the total weight of the laminate was calculated in weight %.

[0098] The coating solutions used in Examples 1 to 11 and Comparative Examples 1 to 4 are shown in Table 1.

[0099] [Carbodiimide crosslinking agent (A)] As a carbodiimide-based crosslinking agent, commercially available "Carbodilite (registered trademark) SV-02" manufactured by Nisshinbo Co., Ltd. (solid content: 40%) was prepared. [Resin (B) having an oxazoline group] A commercially available water-soluble acrylate containing oxazoline groups (Epocross (registered trademark) WS-300, manufactured by Nippon Shokubai Co., Ltd.; solid content: 10%) was prepared as a resin having oxazoline groups. The amount of oxazoline groups in this resin was 7.7 mmol / g.

[0100] [Acrylic resin (C)] As the acrylic resin, a 25% by mass emulsion of a commercially available acrylic acid ester copolymer ("Movinyl (registered trademark) 7980" manufactured by Nichigo Movinyl Co., Ltd.) was prepared.

[0101] [Urethane resin (D)] A commercially available polyester urethane resin dispersion (Mitsui Chemicals' "Takelac (registered trademark) W605"; solid content 30%) was prepared as the urethane resin. The glass transition temperature (Tg) measured by DSC was 100°C. The ratio of aromatic or araliphatic diisocyanate to the total isocyanate components measured by 1H-NMR was 55 mol%. [Silane coupling agent (E)] As a silane coupling agent, a commercially available product "KBM903 (registered trademark)" (solid content 100%) manufactured by Shin-Etsu Chemical Co., Ltd. was prepared. When used, it was diluted with water to give a 2% aqueous solution.

[0102] [Urethane resin (F)] A commercially available polyester urethane resin dispersion (Mitsui Chemicals, Inc.'s "Takelac (registered trademark) WPB341"; solid content 30%) was prepared as the urethane resin. The glass transition temperature (Tg) measured by DSC was 130°C. The proportion of aromatic or araliphatic diisocyanate to the total isocyanate components measured by 1H-NMR was 85 mol%.

[0103] [Urethane resin (G)] A commercially available polyester urethane resin dispersion (DIC "AP201"; solid content 23%) was prepared as the urethane resin. The glass transition temperature (Tg) measured by DSC was 10°C. The ratio of aromatic or araliphatic diisocyanate to the total isocyanate component measured by 1H-NMR was 100 mol%.

[0104] [Gas barrier vinyl alcohol resin (H)] As a vinyl alcohol resin having gas barrier properties, a commercially available water-soluble vinyl alcohol resin (Nichigo G-Polymer (registered trademark) OKS-8049, powder, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was used. was dissolved in water to prepare an aqueous solution with a solid content of 5%.

[0105] [Gas barrier protective layer solution (coating solution 6)] A solution of tetraethoxysilane hydrolyzed with 0.02 mol / L hydrochloric acid was added to a 5 wt % aqueous solution of polyvinyl alcohol resin (PVA) with a saponification degree of 99% and a polymerization degree of 2400 in a weight ratio of SiO2 / PVA = 60 / 40 to prepare a gas barrier protective layer solution (coating solution 6).

[0106] [Coating liquid 1 used for coating layer] The materials were mixed in the following proportions to prepare a coating liquid (resin composition for coating layer). Water 54.40% by mass Isopropanol 25.00% by mass Oxazoline group-containing resin (A) 15.00% by mass Acrylic resin (B) 3.60% by mass Urethane resin (C) 2.00% by mass

[0107] [Coating liquid 2 used for coating layer] The materials were mixed in the following proportions to prepare a coating liquid (resin composition for coating layer). Water 57.80% by mass Isopropanol 25.00% by mass Carbodiimide crosslinking agent (A) 2.10% by mass Urethane resin (F) 8.00% by mass Silane coupling agent (E) 7.10% by mass

[0108] [Coating liquid 3 used for coating protective layer] The following coating materials were mixed to prepare coating liquid 3. Water 30.00% by mass Isopropanol 30.00% by mass Urethane resin (F) 40.00% by mass

[0109] [Coating liquid 4 used for coating protective layer] The following coating materials were mixed to prepare coating liquid 4. Water 17.83% by mass Isopropanol 30.00% by mass Urethane resin (G) 52.17% by mass

[0110] [Coating liquid 5 used for coating protective layer] The following coating agents were mixed to prepare coating liquid 5. Water 20.00% by mass Isopropanol 10.00% by mass Gas barrier vinyl alcohol resin (H) 70.00% by mass

[0111] [Coating liquid 7 used for coating the protective layer] The following coating materials were mixed to prepare coating liquid 7. Water 30.00% by mass Isopropanol 30.00% by mass Urethane resin (D) 40.00% by mass

[0112] [Coating liquid 8 used for coating the protective layer] The following coating materials were mixed to prepare coating liquid 8. Water 22.00% by mass Isopropanol 30.00% by mass Acrylic resin (C) 48.00% by mass

[0113] The methods for producing the laminated films used in each of the Examples and Comparative Examples are described below. The films used in Examples 1 to 11 and Comparative Examples 1 to 4 are shown in Table 1.

[0114] (Preparation of polyester resin recycled from PET bottles) After washing away any remaining beverages and other foreign matter from PET beverage bottles, the resulting flakes were crushed and melted in an extruder. The flakes were filtered twice using successively smaller mesh filters to remove even finer particles, and then filtered a third time using a filter with the smallest mesh size (50 μm) to obtain recycled polyester raw material. The resulting resin had a composition of terephthalic acid / isophthalic acid / ethylene glycol = 97.0 / 3.0 / / 100 (mol%), and the resin's intrinsic viscosity was 0.70 dL / g. This was designated Polyester A.

[0115] (Preparation of base film) Polyester B was a polyethylene terephthalate resin with an intrinsic viscosity of 0.62 dl / g, composed of 100% terephthalic acid / ethylene glycol (mol%) and 100% ethylene glycol (mol%). Polyester C was a masterbatch of polyester B containing 0.3% amorphous silica with an average particle size of 1.5 μm. The raw materials were dried at 125°C for 8 hours under a reduced pressure of 33 Pa. The mixture was mixed in a weight ratio of A / B / C = 70 / 20 / 10 and then fed into a single-screw extruder. The resin temperature was set to 280°C from the extruder through the melt line, filter, and T-die. However, the resin temperature was set to 305°C for 30 seconds from the start of the compression section of the extruder screw, after which it was returned to 280°C.

[0116] The molten material extruded from the T-die was brought into close contact with a cooling roll to form an unstretched sheet. This was then stretched 1.41 times in the machine direction using rolls heated to 118°C with different peripheral speeds (MD1), and further stretched 2.92 times in the machine direction using rolls heated to 128°C with different peripheral speeds (MD2). The machine-stretched sheet was introduced into a tenter, and one side of the film was coated with Coating Solution 1 using a fountain bar coating method. The sheet was introduced into the tenter while drying, preheated to 121°C, and then stretched 4.3 times transversely at 131°C. The heat setting was then performed at 180°C with no relaxation (0%) for 2.5 seconds (TS1), followed by 231°C with 5% relaxation for 3.0 seconds (TS2), followed by 222°C with no relaxation for 2.5 seconds (TS3). Subsequently, the film was cooled at 120° C. for 6.0 seconds in the same tenter, and finally taken up by a winder to obtain a biaxially oriented polyester film having a thickness of 12 μm.

[0117] When preparing the base film layer described in each example and comparative example, laminate films were produced and evaluated in the same manner, except that the blending amounts of resins A / B / C or the coating liquids constituting the coating layer and protective layer were changed as shown in Table 1.

[0118] The method for producing the inorganic thin film layer used in each example and comparative example is described below. The method used in examples 1 to 11 and comparative examples 1 to 4 is shown in Table 1. (Formation of inorganic thin film layer M-1) Aluminum oxide was vapor-deposited onto the base film layer to form the inorganic thin film layer M-1. The method for vapor-depositing aluminum oxide onto the base film layer involved placing the film on the unwinding side of a continuous vacuum deposition machine and running it over a cooled metal drum until the film was wound up. The continuous vacuum deposition machine was then depressurized to 10-4 Torr or less, and 99.99% pure aluminum metal was loaded into an alumina crucible from below the cooling drum. The aluminum metal was then heated and evaporated, and oxygen was supplied to the vapor, causing an oxidation reaction that caused it to adhere and deposit on the film, forming a 10 nm thick aluminum oxide film.

[0119] (Formation of inorganic thin film layer M-2) As the inorganic thin film layer M-2, a composite oxide layer of silicon dioxide and aluminum oxide was formed on the base film layer by electron beam evaporation. The evaporation sources used were 3-5 mm particulate SiO2 (purity 99.9%) and Al2O3 (purity 99.9%). The thickness of the inorganic thin film layer (SiO2 / Al2O3 composite oxide layer) in the film thus obtained (film containing an inorganic thin film layer / coating layer) was 13 nm. The composition of this composite oxide layer was SiO2 / Al2O3 (mass ratio) = 60 / 40.

[0120] (Coating of coating liquid onto vapor-deposited film (lamination of protective layer)) The coating solution prepared above was applied onto the inorganic thin film layer of the obtained vapor-deposited film by gravure roll coating, pre-dried at 110°C, and then dried at 180°C to obtain a protective layer. The coating amount after drying was 0.30 g / m 2 The coating liquid constituting the protective layer was changed as shown in Table 1 for each of the examples and comparative examples.

[0121] In this way, a laminate film having a (coating layer), an inorganic thin film layer, and a protective layer on a substrate film was produced. A laminate was produced from the obtained laminate film and evaluated. The results are shown in Table 1.

[0122] [Table 1] [Industrial Applicability]

[0123] According to the present invention, we have discovered that by using a polyester resin derived from PET bottles, which has a low environmental impact, as a substrate and forming a structure with a specific coating layer or a specific barrier protection layer that has excellent flexibility and adhesion to an inorganic thin film layer, it is possible to improve gas barrier performance before treatment and maintain the barrier properties and adhesion even after severe moist heat treatment. Furthermore, we have discovered that by utilizing the property of the protection layer that dissolves when immersed in a specific solvent, it is possible to easily peel the laminate film from the laminate, thereby completing the present invention. The laminate of the present invention can be easily produced with few processing steps and is highly recyclable, so it is excellent in both economy and production stability, and can provide a gas barrier film with uniform properties.

Claims

1. A laminated body having an inorganic thin film layer directly laminated on one side of a base film, and a sealant layer laminated on one side of a laminated film having a protective layer on the inorganic thin film layer, wherein the laminated body satisfies the following (a) to (d): (a) The base film contains 10% by weight or more of polyester resin recycled from PET bottles. (b) The protective layer of the laminated film contains a urethane resin, and the surface free energy of the protective layer surface is 45 to 60 mN / m. (c) The laminate has a laminate strength of 6.5 N / 15 mm or more, and after immersion in 1-methoxy-2-propanol at 40° C. for 72 hours, the laminate strength is 1.0 N / 15 mm or less. (d) The laminate strength after boiling sterilization at 90°C for 30 minutes is 1.5 N / 15 mm or more.

2. 2. The laminate according to claim 1, wherein the urethane resin contained in the protective layer contains an aromatic component or an aromatic aliphatic component as a constituent component.

3. 3. The laminate according to claim 1, wherein the inorganic thin film layer is an aluminum oxide layer or a layer of a composite oxide of silicon oxide and aluminum oxide.

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