WO2020080131A1 - Layered film - Google Patents

Abstract

[Problem] To provide a layered film suitable for packaging a retort food, or the like, for which the amount of packaging materials can be reduced, which has excellent resistance to bag-tearing, and for which the capacity to stand independently when used as a standing pouch has been sufficiently ensured. [Solution] The layered film comprises at least a base material layer and a sealant layer and is characterized in that: (a) the base material layer is a 9 μm to 25 μm-thick biaxially stretched polyester film containing 70% by mass or more polybutylene terephthalate; (b) the anti-puncture strength of the laminated layered film is 9.0 N or greater; (c) the loop stiffness value X (mN/25mm) of the layered film is 80 or greater; and (e) the total thickness is 59 to 160 μm.

Description

Laminated film

The present invention relates to a laminated film used in the field of packaging foods, pharmaceuticals, industrial products and the like. More specifically, it is a laminated film consisting of a laminated film having an inorganic thin film layer or a metal foil on a base material layer and a sealant layer, instead of using a laminated film of a polyester film and a nylon film as the base material layer. The present invention also relates to a laminated film having excellent puncture resistance and bag puncture resistance even when a single layer of polybutylene terephthalate (hereinafter abbreviated as PBT) film is substituted, and having excellent self-supporting property for a standing pouch.

BACKGROUND ART Conventionally, in order to prevent deterioration of contents such as foods, packaging materials in which various plastic films, papers, base materials such as metal foils are laminated have been developed. In general, a heat-sealing layer is provided on the innermost layer of these packaging materials, and a bag is made into various forms by stacking and sealing them. Next, the packaged product in the final form is completed by filling the contents from the opening and heat-sealing them. Particularly in food applications, retort pouches are widely known as a packaging form that can be stored for a long period of time, and have already been put to practical use in all fields.
Furthermore, in recent years, among the above-mentioned retort pouches, the structure of the retort pouch itself is self-supporting so that it can be displayed at the store as it is without putting it in the outer box for the purpose of reducing the packaging material that becomes waste after use. Standing pouches that have been used are becoming popular.

On the other hand, the basic performance required for retort packaging materials is safety, tasteless and odorless, hot water resistance, light shielding property, aroma retention, discoloration resistance, various gas barrier properties, strength against pressure, impact, puncture, etc. , Flex resistance, and hermeticity, etc., and an optimal laminate structure is designed according to the conditions of heat treatment, the type of contents, the internal capacity, and the like.
For example, biaxially oriented polyethylene terephthalate film (hereinafter abbreviated as OPET), impact resistance, pinhole resistance, and puncture resistance to impart hot water resistance, waist (self-supporting), gloss, printability, and aroma retention. Biaxially stretched nylon film (hereinafter abbreviated as ONy) to impart heat resistance, aluminum foil or aluminum vapor deposition film or gas barrier coating layer to block light, oxygen and water vapor, and unstretched polypropylene film to impart heat sealability. A polyethylene film or the like (hereinafter abbreviated as CPP) is selected, and a retort packaging material is obtained by laminating these materials by dry lamination or the like.

Regarding the laminate structure of the retort packaging material, for example, OPET // ONy // CPP, OPET // AL // CPP, OPET // ONy // AL // CPP, OPET // AL // ONy // CPP A typical structure is a stack of the above. (See Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4).
Although OPET and ONy are generally used as the base material layer of the packaging material for retort, OPET has the advantage of high hot water resistance, but has the weak point of low impact strength, puncture strength, and pinhole resistance. It was On the other hand, although ONy has high impact strength and puncture strength, since the film itself has hygroscopicity, it has a drawback that when contacted with hot water, the strength is lowered by hydrolysis. From the above viewpoints, particularly under severe retort conditions of 130 ° C. or higher, or when high compressive strength and impact resistance are required, in order to compensate for the disadvantages of both base materials, OPET and ONy are used as base material layers. Are used together.

However, by using both base materials together, there were problems in terms of resource saving and impact on environmental load. Further, there is room for improvement in terms of workability because the number of laminating processes increases.
Therefore, in recent years, attempts have been made to supplement the above-mentioned laminated structure of OPET and ONy with a single-layer film.
For example, Patent Documents 6 and 7 disclose biaxially stretched films containing PBT. According to such a technique, since it is excellent in impact resistance and puncture resistance, and can withstand severe heat treatment such as retort treatment, a configuration in which OPET and ONy are used in combination can be replaced with a single-layer film. there is a possibility.
However, when the film laminated with the sealant layer with the base material layer as one layer is processed into a packaging bag such as a standing pouch, the waist feeling of the laminated film is insufficient, and thus the standing pouch lacks independence. There was a problem.

Japanese Utility Model Sho 63-31961 Japanese Patent Laid-Open No. 5-38779 JP, 2002-326306, A JP, 2005-178311, A JP, 2017-094746, A WO2014 / 077197

The present invention has been made against the background of such problems of the conventional technology. That is, the problem of the present invention, it is possible to reduce the packaging material, excellent bag puncture resistance, it is possible to ensure sufficient independence when used as a standing pouch, in packaging such as retort food. It is to provide a suitable laminated film.

The inventors of the present invention set the rigidity of a laminated film obtained by laminating a film base material layer containing polybutylene terephthalate (PBT) as a main component and a sealant layer to a specific range so that even a single base material layer has high water resistance. It has been found that it has excellent impact resistance and can maintain the self-supporting property when processed into a standing pouch.

That is, the present invention has the following configurations.
(1) A laminated film having a total thickness of 59 to 160 μm, comprising at least a base material layer and a sealant layer,
(A) the base material layer is a biaxially stretched polyester film having a thickness of 9 μm to 25 μm and containing 70% by mass or more of polybutylene terephthalate,
(B) The piercing strength of the laminated film is 9.0 N or more,
(C) A laminated film having a numerical value X (mN / 25 mm) of loop stiffness of the laminated film of 80 or more.
(2) The laminated film as described in (1), which has an inorganic thin film layer on at least one surface of the base material layer.
(3) The laminated film as described in (2), wherein the inorganic thin film layer is a layer made of an oxide of silicon oxide and / or aluminum oxide.
(4) The laminated film as described in (2) or (3), which has an adhesion layer between the base material layer and the inorganic thin film layer.
(5) The laminated film according to any one of (2) to (4), which has a protective layer on the inorganic thin film layer.
(6) A packaging bag comprising the laminated film according to any one of (1) to (5) above.
(7) The packaging bag according to (6), which is used as a standing pouch.
(8) The packaging bag according to (7), wherein the content Y (g) of the standing pouch satisfies the following formula (1), where X is a numerical value of the loop stiffness of the laminated film.
1.8X ≤ Y ≤ 3.8X Formula (1)
(9) The packaging bag according to any one of (6) to (8), which is used for a retort.
(10) The packaging bag according to any one of (6) to (8), which is used for heating a microwave oven.

According to the present invention, it is possible to reduce the amount of packaging material, it is excellent in bag puncture resistance, and a laminated film suitable for liquid packaging such as retort foods that can ensure sufficient self-supporting even when used as a standing pouch. And it has become possible to provide a packaging bag.

It is a top view which shows the shape of the standing pouch produced using the laminated film which concerns on this invention. It is a perspective view which shows the shape of the standing pouch produced using the laminated film which concerns on this invention.

1: Storage part 2: Side seal part 3: Top seal part 4: Bottom part 5: Length 6: Width 7: Bottom part fold

Hereinafter, the present invention will be described in detail.
[Substrate layer film]
As the base material layer used in the present invention, a film containing PBT as a main component is used.
The content of PBT in the base material layer is preferably 60% by mass or more, and more preferably 70% by mass or more. If it is less than 60% by mass, the impact strength or the pinhole resistance will be deteriorated and the film characteristics will not be sufficient.
The PBT used as the main constituent component of the base material layer preferably contains 90 mol% or more of terephthalic acid as a dicarboxylic acid component, more preferably 95 mol% or more, and further preferably 98 mol% or more. It is preferably 100 mol%. As the glycol component, 1,4-butanediol is preferably 90 mol% or more, more preferably 95 mol% or more, further preferably 97 mol% or more, and most preferably 1,4-butane at the time of polymerization. This means that it does not contain any byproducts other than those produced by the ether bond of the diol.

The base material layer used in the present invention may contain a polyester resin other than PBT for the purpose of adjusting the film-forming property during stretching and the mechanical properties of the obtained film.
Polyester resins other than PBT include polyethylene terephthalate (hereinafter abbreviated as PET), polyethylene naphthalate, polybutylene naphthalate and polypropylene terephthalate, and isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid. , PBT resin copolymerized with at least one dicarboxylic acid selected from the group consisting of azelaic acid and sebacic acid, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5 -Pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol and polycarbonate At least one diol component selected from the group consisting of diol is copolymerized PBT resin.

The upper limit of the amount of polyester resin other than PBT added is 40% by mass or less, preferably 30% by mass or less. If the addition amount of the polyester resin other than PBT exceeds 40% by mass, the mechanical properties as PBT will be impaired, and impact strength, pinhole resistance, or bag-breaking resistance will be insufficient, and transparency and gas barrier properties will be insufficient. May decrease.

The lower limit of the intrinsic viscosity of the PBT resin used in the present invention is preferably 0.9 dl / g, more preferably 0.95 dl / g, and further preferably 1.0 dl / g.
When the intrinsic viscosity of the raw material PBT resin is less than 0.9 dl / g, the intrinsic viscosity of the film obtained by film formation decreases, and the piercing strength, impact strength, pinhole resistance, or bag puncture resistance decreases. Then it may happen.
The upper limit of the intrinsic viscosity of the PBT resin is preferably 1.3 dl / g. If it exceeds the above range, the stress during stretching becomes too high, and the film formability may deteriorate. When PBT having a high intrinsic viscosity is used, the melt viscosity of the resin becomes high, so that it is necessary to raise the extrusion temperature to a high temperature. However, if the PBT resin is extruded at a higher temperature, a decomposed product may be easily generated.

The PBT resin may contain conventionally known additives such as lubricants, stabilizers, colorants, antistatic agents, and ultraviolet absorbers, if necessary.

As the type of the above-mentioned lubricant, in addition to inorganic lubricants such as silica, calcium carbonate and alumina, organic lubricants are preferable, silica and calcium carbonate are more preferable, and silica is particularly preferable in view of reducing haze. By these, transparency and slipperiness can be exhibited.

The lower limit of the concentration of the lubricant is preferably 100 ppm, more preferably 500 ppm, further preferably 800 ppm. When it is less than the above range, the slipperiness of the base layer film may decrease. The upper limit of the concentration of the lubricant is preferably 20000 ppm, more preferably 10000 ppm, and further preferably 1800 ppm. If it exceeds the above range, the transparency may decrease.

The substrate layer film in the present invention preferably has a resin of the same composition over the entire area of the film.
The lower limit of the thickness of the substrate layer film in the present invention is preferably 3 μm, more preferably 5 μm, and further preferably 8 μm. When the thickness is 3 μm or more, the strength of the base material layer film is sufficient.
The upper limit of the thickness of the base layer film is preferably 100 μm, more preferably 75 μm, and further preferably 50 μm. When it is 100 μm or less, the processing for the purpose of the present invention becomes easier.

Next, the method for producing the base layer film used in the present invention will be specifically described. It is not limited to these.
[Unstretched sheet forming step in base layer film production]
First, the film raw material is vacuum dried or hot air dried. Next, the raw materials are weighed and mixed, supplied to an extruder, heated and melted, and melt cast into a sheet.
Further, the molten resin sheet is brought into close contact with a cooling roll (casting roll) by an electrostatic application method to be cooled and solidified to obtain an unstretched sheet. The electrostatic application method, in the vicinity of the resin sheet in a molten state is in contact with the rotating metal roll, by applying a voltage to the electrode installed in the vicinity of the opposite surface of the surface of the resin sheet in contact with the rotating metal roll, In this method, the resin sheet is charged and the resin sheet and the rotating cooling roll are brought into close contact with each other.

The lower limit of the heating and melting temperature of the resin is preferably 200 ° C, more preferably 250 ° C, and further preferably 260 ° C. If it is less than the above, ejection may be unstable. The upper limit of the resin melting temperature is preferably 280 ° C, more preferably 270 ° C. When it exceeds the above range, the decomposition of the resin proceeds and the film becomes brittle.

When casting a molten polyester resin on an extrusion cooling roll, it is preferable to reduce the difference in crystallinity in the width direction of the unstretched sheet. As a specific method for this, when the molten polyester resin is extruded and cast, the molten raw material resin is multilayered and cast, and the cooling roll temperature is set to a low temperature.

The method for forming the molten raw material resin into multiple layers is not particularly limited, but a static mixer and / or a multi-layer feed block is preferable from the viewpoint of facility simplicity and maintainability.
When the molten raw material resin is formed into multiple layers, the number of layers is preferably 60 or more. It is more preferably 500. If the number of laminated layers is too small, the distance between layer interfaces becomes long and the crystal size becomes too large, the difference in crystallinity in the width direction and the crystallinity near both ends of the sheet increase, and the film formation becomes unstable. The upper limit of the number of layers is not particularly limited, but it is preferably 100,000, more preferably 10,000, and further preferably 7,000. Even if the theoretical number of layers is extremely increased, the effect may be saturated.

When performing multi-layering with a static mixer, the theoretical number of layers can be adjusted by selecting the number of elements in the static mixer. The static mixer is generally known as a static mixer (line mixer) having no driving unit, and the fluid that has entered the mixer is sequentially stirred and mixed by the elements. However, when the high-viscosity fluid is passed through the static mixer, the high-viscosity fluid is divided and laminated, and a laminated fluid is formed. Each time one element of the static mixer is passed, the high-viscosity fluid is divided into two and then merged and laminated. Therefore, when the high-viscosity fluid is passed through the static mixer having the number of elements n, the laminated fluid having the theoretical number of layers N = (2 to the n-th power) is formed.

The upper limit of the cooling roll temperature when the molten polyester resin is cast on the extrusion cooling roll is preferably 40 ° C. If it exceeds the above range, the crystallinity becomes too high, and stretching may be difficult. The upper limit of the cooling roll temperature is preferably 25 ° C. When the temperature of the cooling roll is set within the above range, it is preferable to reduce the humidity of the environment near the cooling roll in order to prevent dew condensation. It is preferable to reduce the temperature difference in the width direction of the cooling roll surface. The lower limit of the cooling roll temperature is preferably -10 ° C. If it is less than the above, the effect of suppressing crystallization may be saturated. The thickness of the unstretched sheet is preferably in the range of 15 to 2500 μm.

[Vertical Stretching Step and Horizontal Stretching Step in Manufacturing Base Layer Film]
Next, the stretching method will be described. The stretching method can be simultaneous biaxial stretching or sequential biaxial stretching, but in order to increase the puncture strength, it is necessary to increase the degree of plane orientation, and in addition, the film forming speed is high and the productivity is high. In the above, sequential biaxial stretching is the most preferable.

The lower limit of the stretching temperature in the longitudinal stretching direction is preferably 55 ° C, more preferably 60 ° C. If the temperature is 55 ° C. or higher, breakage hardly occurs. Further, since the degree of longitudinal orientation of the film does not become too strong, shrinkage stress at the time of heat setting treatment can be suppressed, and a film with little distortion of molecular orientation in the width direction can be obtained. The upper limit of the stretching temperature in the longitudinal stretching direction is preferably 100 ° C, more preferably 95 ° C. When the temperature is 100 ° C. or lower, the orientation of the film does not become too weak and the mechanical properties of the film do not deteriorate.

The lower limit of the stretching ratio in the longitudinal stretching direction is preferably 2.8 times, particularly preferably 3.0 times. When it is 2.8 times or more, the plane orientation degree becomes large, the piercing strength of the film is improved, and the thickness accuracy of the film is improved.
The upper limit of the stretching ratio in the longitudinal stretching direction is preferably 4.3 times, more preferably 4.0 times, and particularly preferably 3.8 times. When it is 4.3 times or less, the degree of orientation in the lateral direction of the film does not become too strong, the shrinkage stress at the time of heat setting treatment does not become too large, and the distortion of the molecular orientation in the lateral direction of the film becomes small. As a result, the straight-line tearability in the vertical direction is improved. In addition, the effect of improving mechanical strength and thickness unevenness is saturated in this range.

The lower limit of the stretching temperature in the transverse stretching direction is preferably 60 ° C, and if it is 60 ° C or more, breakage may be difficult to occur. The upper limit of the stretching temperature in the transverse stretching direction is preferably 100 ° C., and when it is 100 ° C. or less, the degree of orientation in the transverse direction becomes large and the mechanical properties are improved.

The lower limit of the stretching ratio in the transverse stretching direction is preferably 3.5 times, more preferably 3.6 times, and particularly preferably 3.7 times. If it is 3.5 times or more, the degree of orientation in the lateral direction does not become too weak, and the mechanical characteristics and thickness unevenness are improved. The upper limit of the stretching ratio in the transverse stretching direction is preferably 5 times, more preferably 4.5 times, and particularly preferably 4.0 times. When it is 5.0 times or less, the effect of improving mechanical strength and thickness unevenness becomes maximum (saturated) even in this range.

[Heat-setting step in base layer film production]
The lower limit of the heat setting temperature in the heat setting step is preferably 195 ° C, more preferably 200 ° C. When the temperature is 195 ° C. or higher, the heat shrinkage rate of the film becomes small and the inorganic thin film layer is less likely to be damaged even after the retort treatment, so that the gas barrier property is improved. The upper limit of the heat setting temperature is preferably 220 ° C., and when it is 220 ° C. or less, the base film layer does not melt and becomes hard to be brittle.

[Thermal relaxation process in base layer film production]
After the heat setting step, heat relaxation treatment is performed for the purpose of improving thermal dimensional stability.
The lower limit of the temperature in the thermal relaxation step is preferably 180 ° C, more preferably 200 ° C. When the temperature is 180 ° C. or higher, the heat shrinkage rate of the film becomes small, and the inorganic thin film layer is less likely to be damaged even after the retort treatment, so that the gas barrier property is improved. The upper limit of the temperature of the heat relaxation step is preferably 220 ° C., and when it is 220 ° C. or less, the base film layer does not melt and becomes hard to be brittle.
The lower limit of the relaxation rate in the heat relaxation step is preferably 0.5%. If it is 0.5% or more, fracture may be less likely to occur during heat setting. The upper limit of the relaxation rate is preferably 10%. When it is 10% or less, the shrinkage in the longitudinal direction during heat setting becomes small, and as a result, the distortion of the molecular orientation at the end of the film becomes small and the straight-line tearability is improved. In addition, sagging of the film is less likely to occur, and uneven thickness is less likely to occur.

[Cooling process in base layer film production]
In the cooling step after performing the relaxation in the thermal relaxation section step, the temperature of the surface of the end portion of the polyester film is preferably 80 ° C. or lower.
If the temperature of the end portion of the film after passing through the cooling step exceeds 80 ° C., the end portion is stretched by the tension applied when the film is wound, and as a result, the heat shrinkage ratio in the longitudinal direction of the end portion becomes high. As a result, the heat shrinkage distribution in the width direction of the roll becomes uneven, and when such a roll is heated and transported to perform vapor deposition processing, streak-like wrinkles occur and the gas barrier finally obtained. The physical properties of the film may become uneven in the width direction.

In the cooling step, as a method for controlling the surface temperature of the film end portion to 80 ° C. or less, the temperature and air flow rate in the cooling step are adjusted, and a shield plate is provided on the center side in the width direction of the cooling zone to select the end portion. It is possible to use a method of cooling the film or a method of locally blowing cold air to the end portion of the film.

The lower limit of the degree of orientation (ΔNx) in the MD direction of the substrate layer film in the present invention is preferably 0.04, more preferably 0.045, and further preferably 0.05. If it is less than the above range, the orientation is weak, so that sufficient impact strength as a substrate layer film cannot be obtained, and the bag breaking resistance is deteriorated. Further, when the inorganic thin film layer and the protective layer are provided on the substrate layer film to form a laminated film, the tensile strength and temperature applied during the formation of the protective film facilitates elongation, and the inorganic thin film layer is cracked. May decrease.

The upper limit of the degree of orientation (ΔNx) in the MD direction of the substrate film in the present invention is preferably 0.09, more preferably 0.085, and further preferably 0.08. Within the above range, the mechanical properties and linear tearability of the base layer film will be more preferable.
The degree of orientation (ΔNx) in the MD direction is ΔNx = Nx− (Ny + Nz) / 2 by measuring the refractive index Nx in the MD direction, the refractive index Ny in the TD direction, and the refractive index Nz in the thickness direction with an Abbe refractometer. Calculated by the formula.

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

Further, the base layer film in the present invention may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, surface roughening treatment, as long as the object of the present invention is not impaired, and a known anchor. It may be coated, printed, decorated, or the like.

[Easy adhesion layer and method for forming the same]
An easy-adhesion layer can be provided on the base layer film used for the laminated film of the present invention. Particularly when an inorganic thin film layer is formed on the base material layer film, it is preferable to provide an easy adhesion layer between the base material layer film and the inorganic thin film layer in order to secure gas barrier properties and laminate strength after retort treatment. .
As the easy-adhesion layer provided on the substrate layer film, urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based resins, etc., epoxy-based, isocyanate-based, melamine-based curing agents, etc. The thing which added is mentioned. Examples of the solvent 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; ethylene glycol monomethyl ether. And other polyhydric alcohol derivatives. The resin composition used for these adhesion layers preferably contains 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 the retort treatment.

Among the resin compositions used for the easy-adhesion layer, it is preferable to use a mixture of a resin containing an oxazoline group, an acrylic resin and a urethane resin. The oxazoline group has a high affinity with the inorganic thin film, and can react with the oxygen deficiency part of the inorganic oxide generated during the formation of the inorganic thin film layer and the metal hydroxide, and exhibits a strong adhesiveness with the inorganic thin film layer. . The unreacted oxazoline group present in the easy-adhesion layer can react with the carboxylic acid terminal generated by the hydrolysis of the base layer film and the easy-adhesion layer to form a crosslink.

As a method of forming the easily adhesive layer, a conventionally known method such as a coating method can be adopted. Among the coating methods, the offline coating method and the in-line coating method can be mentioned as suitable methods. For example, in the case of the in-line coating method performed in the process of manufacturing the base material layer film, the conditions of drying and heat treatment during coating depend on the coat thickness and the conditions of the apparatus, but immediately after coating, the film is sent to the stretching process in the perpendicular direction. Drying is preferably carried out in the preheating zone or the stretching zone of the stretching step, and in such a case, it is preferable that the temperature is usually about 50 to 250 ° C.

[Inorganic thin film layer and method for forming the same]
A gas barrier layer can be provided on the base material layer of the laminated film of the present invention. The inorganic thin film layer and its forming method will be described.
The inorganic thin film layer is a thin film made of metal or inorganic oxide. The material forming the inorganic thin film layer is not particularly limited as long as it can be formed into a thin film, but 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. The thing is preferably mentioned. In particular, a composite oxide of silicon oxide and aluminum oxide is preferable from the viewpoint of achieving both flexibility and denseness of the thin film layer. In this composite oxide, the mixing ratio of silicon oxide and aluminum oxide is preferably in the range of 20 to 70% by mass of Al in terms of the mass ratio of metal components. If the Al concentration is less than 20% by mass, the water vapor barrier property may decrease. On the other hand, if it exceeds 70% by mass, the inorganic thin film layer tends to become hard, and the film may be destroyed during secondary processing such as printing or laminating, and the gas barrier property may deteriorate. The silicon oxide mentioned here is various silicon oxides such as SiO and SiO ₂ or a mixture thereof, and the aluminum oxide is various aluminum oxides such as AlO and Al ₂ O ₃ or a mixture thereof.

The thickness of the inorganic thin film layer is usually 1 to 100 nm, preferably 5 to 50 nm. When the film thickness of the inorganic thin film layer is less than 1 nm, it may be difficult to obtain a satisfactory gas barrier property. On the other hand, even if the inorganic thin film layer exceeds 100 nm and is excessively thick, a corresponding gas barrier property improving effect is obtained. Therefore, it is rather disadvantageous in terms of bending resistance and manufacturing cost.

The method for forming the inorganic thin film layer is not particularly limited, and known vapor deposition methods such as vacuum vapor deposition method, sputtering method, physical vapor deposition method (PVD method) such as ion plating method, or chemical vapor deposition method (CVD method) are known. The method may be adopted as appropriate. Hereinafter, a typical method of forming an inorganic thin film layer will be described by taking a silicon oxide / aluminum oxide thin film as an example. For example, when the vacuum vapor deposition method is adopted, a mixture of SiO ₂ and Al ₂ O _3, a mixture of SiO ₂ and Al, or the like is preferably used as a vapor deposition material. Particles are usually used as these vapor deposition raw materials. At this time, the size of each particle is preferably such that the pressure during vapor deposition does not change, and the preferable particle diameter is 1 mm to 5 mm. For heating, methods such as resistance heating, high frequency induction heating, electron beam heating, and laser heating can be adopted. It is also possible to introduce oxygen, nitrogen, hydrogen, argon, carbon dioxide gas, water vapor or the like as a reaction gas, or to adopt reactive vapor deposition using means such as ozone addition or ion assist. Furthermore, film forming conditions can be arbitrarily changed, such as applying a bias to the object to be vapor-deposited (laminated film to be subjected to vapor deposition), heating or cooling the object to be vapor-deposited. The vapor deposition material, the reaction gas, the bias of the object to be vapor-deposited, the heating / cooling and the like can be similarly changed when the sputtering method or the CVD method is adopted.

[Protective layer and method for forming the same]
When the gas barrier layer is provided on the base layer film of the laminated film of the present invention, a protective layer can be further provided thereon. The protective layer and the method for forming the protective layer will be described.
When the gas barrier layer is an inorganic thin film layer such as a metal oxide layer, the inorganic thin film is not a completely dense film, and minute defects are scattered. By forming a protective layer by coating a specific protective layer resin composition described below on the inorganic thin film layer, the resin in the protective layer resin composition penetrates into the defective portion of the inorganic thin film layer, resulting in The effect of stabilizing the gas barrier property is obtained. In addition, by using a material having a gas barrier property for the protective layer itself, the gas barrier performance of the laminated film can be greatly improved.

Examples of the protective layer include urethane-based resins, polyester-based resins, acrylic-based resins, titanate-based resins, isocyanate-based resins, imine-based resins, polybutadiene-based resins, epoxy-based curing agents, isocyanate-based curing agents, and melamine. Examples include those to which a curing agent such as a system curing agent is added. Examples of the solvent for the resin 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 ethylene glycol. Examples thereof include polyhydric alcohol derivative-based solvents such as monomethyl ether.
The urethane resin has a polar group of urethane bond interacting with the inorganic thin film layer and also has flexibility due to the presence of the amorphous portion, so that it is possible to suppress damage to the inorganic thin film layer even when a bending load is applied. Therefore, it is preferable.

The acid value of the urethane resin is preferably in the range of 10 to 60 mgKOH / g. It is more preferably within the range of 15 to 55 mgKOH / g, and even more preferably within the range of 20 to 50 mgKOH / g. When the acid value of the urethane resin is within the above range, the liquid stability is improved when it is made into an aqueous dispersion, and the protective layer can be uniformly deposited on the highly polar inorganic thin film, resulting in a good coat appearance. Becomes
The urethane resin has a glass transition temperature (Tg) of preferably 80 ° C. or higher, more preferably 90 ° C. or higher. By setting Tg to 80 ° C. or higher, it is possible to reduce swelling of the protective layer due to molecular motion in the wet heat treatment process (temperature increase-heat retention-temperature decrease).

As the urethane resin, it is more preferable to use a urethane resin containing an aromatic diisocyanate or an araliphatic diisocyanate as a main constituent from the viewpoint of improving gas barrier properties.
Among them, it is particularly preferable to contain the metaxylylene diisocyanate component. By using the above resin, the cohesive force of the urethane bond can be further increased by the stacking effect of aromatic rings, and as a result, good gas barrier properties can be obtained.

In the present invention, the proportion of aromatic diisocyanate or araliphatic diisocyanate in the urethane resin is preferably in the range of 50 to 100 mol% in 100 mol% of the polyisocyanate component. The ratio of the total amount of aromatic diisocyanate or araliphatic diisocyanate is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, and further preferably 80 to 100 mol%. As such a resin, "Takelac (registered trademark) WPB" series commercially available from Mitsui Chemicals, Inc. can be preferably used. When the ratio of the total amount of the aromatic diisocyanate or the araliphatic diisocyanate is less than 50 mol%, good gas barrier properties may not be obtained.

The urethane resin preferably has a carboxylic acid group (carboxyl group) from the viewpoint of improving the affinity with the inorganic thin film layer. In order to introduce a carboxylic acid (salt) group into the urethane resin, for example, a polyol compound having a carboxylic acid group such as dimethylolpropionic acid and dimethylolbutanoic acid may be introduced as a copolymer component. Further, the urethane resin of the water dispersion can be obtained by synthesizing the carboxylic acid group-containing urethane resin and then neutralizing it with a salt forming agent. Specific examples of the salt forming agent include ammonia, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, tri-n-butylamine and other trialkylamines, N-methylmorpholine, N-ethylmorpholine and other N -N-dialkylalkanolamines such as -alkylmorpholines, N-dimethylethanolamine, N-diethylethanolamine and the like can be mentioned. These may be used alone or in combination of two or more.

The upper limit of the heat shrinkage rate after heating the base material layer of the present invention in the MD direction (longitudinal stretching direction) at 150 ° C. for 15 minutes is preferably 4.0%, more preferably 3.0%, and further preferably Is 2%. If the upper limit is exceeded, the inorganic thin film layer may crack due to the dimensional change of the base layer film that occurs in the protective film forming step or high temperature treatment such as retort sterilization treatment, and not only the gas barrier property may deteriorate, but also printing etc. Pitch deviation may occur due to dimensional changes during processing.

The lower limit of the heat shrinkage rate after heating the base material layer in the MD direction at 150 ° C. for 15 minutes in the present invention is preferably 1%. If it is less than the above, the tension tends to increase due to the tension applied in the protective film forming step after forming the inorganic thin film layer, and the gas barrier property may be deteriorated. Further, it may be mechanically brittle.

The upper limit of the heat shrinkage ratio after heating the base material layer in the present invention in the TD direction (transverse stretching direction) at 150 ° C. for 15 minutes is preferably 3.0%, more preferably 2.0%, and It is preferably 1%. If the upper limit is exceeded, the inorganic thin film layer may crack due to the dimensional change of the base layer film that occurs in the protective film forming step or high temperature treatment such as retort sterilization treatment, and not only the gas barrier property may deteriorate, but also printing etc. Pitch deviation may occur due to dimensional changes during processing.

The lower limit of the heat shrinkage ratio after heating the base material layer in the TD direction of the present invention at 150 ° C. for 15 minutes in the TD direction is preferably −1.0%. If it is less than the above, the improvement effect cannot be further obtained. Further, it may be mechanically brittle.

[Laminated film and method for forming the same]
The laminated film of the present invention is a laminated film including at least a base layer film and a sealant layer. That is, it is a film in which a heat-sealable resin layer called a sealant is laminated on a base material layer film.
The heat-sealable resin layer is usually laminated on the substrate layer film by an extrusion laminating method or a dry laminating method.
The heat-sealable resin layer is usually provided on the upper side of the inorganic thin film layer, but it may be provided on the outer side of the base material layer film (the surface opposite to the inorganic thin film layer side).
The thermoplastic polymer that forms the heat-sealable resin layer may be any polymer that can sufficiently exhibit heat-sealability, such as high-density polyethylene (abbreviated as HDPE), low-density polyethylene (abbreviated as LDPE), and linear A polyethylene resin such as low density polyethylene (abbreviated as LLDPE), a polypropylene resin, an ethylene-vinyl acetate copolymer, an ethylene-α-olefin random copolymer, an ionomer resin or the like can be used.

Furthermore, the laminated film of the present invention may have at least one or more printed layers, other plastic base materials and / or paper base materials, and metal foils laminated on the outside and / or between the layers.

As the printing ink for forming the printing layer, water-based and solvent-based resin-containing printing inks can be preferably used. Examples of the resin used in the printing ink here include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. Printing inks include antistatic agents, light blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, crosslinkers, antiblocking agents, antioxidants, etc. The additive may be included. The printing method for providing the printing layer is not particularly limited, and known printing methods such as an offset printing method, a gravure printing method and a screen printing method can be used. For drying the solvent after printing, known drying methods such as hot air drying, hot roll drying and infrared ray drying can be used.

The lower limit of the numerical value X (mN / 25 mm) of loop stiffness of the laminated film of the present invention is preferably 80, more preferably 90, and most preferably 100.
Here, the loop stiffness refers to the repulsive force of the loop measured by forming a loop using a film cut into a strip of a predetermined size and crushing the loop in the radial direction by a predetermined amount, and the rigidity of the film. Is an index representing.
If the loop stiffness of the laminated film is less than the above, it is not possible to secure the self-sustainability of the standing pouch even when the internal capacity is small, and problems such as crushing during display at the store occur. The higher the loop stiffness value, the higher the rigidity of the laminated film. The method for measuring loop stiffness will be described later.

Further, when the content Y (g) of the standing pouch is set within the range of the following formula (1) with respect to the numerical value X of the loop stiffness of the laminated film of the present invention, a packaging bag having good self-standing can be manufactured. .
1.8X ≤ Y ≤ 3.8X Formula (1)

As described above, by using the laminated film of the present invention, even after subjected to wet heat treatment, it has excellent piercing strength, bag puncture resistance, bending resistance, and is sufficient even when used as a standing pouch. Independence can be secured. Conventionally, packaging bags such as standing pouches, which were conventionally made of a laminated film using a base film obtained by laminating OPET and ONy, can be made of a laminated film made of a single layer of the base film, so that it can be used for retort or electronic applications. It can be widely applied as a food packaging material for heating in a microwave oven.

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 film was evaluated by the following measuring methods.

[Thickness of base layer film]
In accordance with JIS K7130-1999 A method, measurement was performed using a dial gauge.

[Pinhole resistance of laminated film]
The laminated film obtained below was cut into a size of 20.3 cm (8 inches) × 27.9 cm (11 inches), and the rectangular test film after the cutting was subjected to a condition of a temperature of 23 ° C. and a relative humidity of 50%. Then, it was conditioned for 24 hours or more. Then, the rectangular test film is wound into a cylindrical shape having a length of 20.32 cm (8 inches). Then, one end of the cylindrical film was fixed to the outer periphery of a disk-shaped fixed head of a Gelbo flex tester (manufactured by Rigaku Kogyo Co., Ltd., NO.901 type) (in accordance with the standard of MIL-B-131C), and the cylindrical film was formed. The other end of was fixed to the outer circumference of the disk-shaped movable head of the tester facing the fixed head with a distance of 17.8 cm (7 inches).
Then, the movable head is rotated 440 ° while approaching the fixed head in the direction of 7.6 cm (3.5 inches) along the axes of the two heads facing each other in parallel, and then is rotated 6.4 cm (without rotating). 2.5-inch) Straight running, and then those operations are performed in the opposite direction to return the movable head to the initial position. A 1-cycle bending test is performed at a speed of 40 cycles per minute and 2000 cycles in succession. I repeated. Implementation was carried out at 5 ° C.
After that, the number of pinholes generated in a portion within 17.8 cm (7 inches) x 27.9 cm (11 inches) excluding the portions fixed to the outer periphery of the fixed head and the movable head of the tested film was measured (that is, The number of pinholes per 497 cm ² (77 square inches) was measured).

[Puncture strength of laminated film]
The obtained laminated film was sampled into a 5 cm square, and a digital force gauge “ZTS-500N” manufactured by Imada Co., Ltd., a motorized measuring stand “MX2-500N” and a piercing jig “TKS-250N” were used in accordance with JIS Z1707. The puncture strength of the film was measured. The unit is indicated by N.

[Loop stiffness of laminated film]
As a sample for loop stiffness measurement, a strip-shaped film having a width of 25.4 mm and a width of 110 mm was cut out from the laminated film prepared in Examples and Comparative Examples. At this time, the longitudinal direction of the strip-shaped film was made to coincide with the measurement target direction. The cut strip-shaped film was set on a loop stiffener tester manufactured by Toyo Seiki Co., Ltd., and the repulsive force was measured. The measurement frequency was 50 Hz. The repulsive force value (mN) obtained by the measurement was used as the loop stiffness.

[Standing pouch independence]
(1) Preparation of Standing Pouch A standing pouch having the shape shown in FIGS. 1 and 2 was prepared using the laminated films shown in Examples, Comparative Examples and Reference Examples described later.
The outer dimensions of the standing pouch body corresponded to the volume of water to be filled and were set to the dimensions shown in Table 1.
The heat seal part on the bottom has a warp curved part on the upper part like the normal standing pouch, the lower side of the curved part is heat-sealed, and at the bottom of the curved part, the length of the pouch to the lower end is 5 mm. The bottom portion was formed by heat-sealing with a pattern having a seal portion, and the body portion was formed by heat-sealing the left and right sides of the pouch with a heat-sealing width of 5 mm.
The unsealed upper part was opened as an opening for filling the contents.
After that, each of the unsealed upper openings was filled with water having the volume shown in Table 1 as a content, and then the openings were degassed and sealed to seal the pouches, thereby producing standing pouches for self-supporting evaluation. .
In addition, the temperature at the time of heat sealing when producing a standing pouch was 160 ° C. × 1 second for LLDPE and 200 ° C. × 1 second for an unstretched polypropylene film.
(2) Evaluation of independence The evaluation of independence was evaluated by ○, △, × according to the following criteria.
・ Independence ○: Independence was maintained without bending the bottom of the standing pouch.
Δ: The standing part was maintained, although the bottom part of the standing pouch was slightly deformed.
X: The bottom of the standing pouch was bent, and the self-supporting state could not be maintained.

 

 

The details of the raw material resins and the coating liquids used in the examples and comparative examples are described below.
1) PBT resin: 1100-211XG (manufactured by CHANG CHUN PLASTICS CO., LTD., Intrinsic viscosity 1.28 dl / g) was used as the PBT resin used in the film production of the base layer films A1 to A3 described later.
2) PET resin: PET resin having a specific viscosity of 0.62 dl / g, manufactured by Toyobo Co., Ltd. was used as the PET resin used in the film production of the substrate layer films A1 to A3 described later.

3) Resin (A) having an oxazoline group for the easy-adhesion layer: As a resin having an oxazoline group, a commercially available water-soluble oxazoline group-containing acrylate (“Epocros (registered trademark) WS-300” manufactured by Nippon Shokubai Co., Ltd .; solid content) 10%) was prepared. The amount of oxazoline groups in this resin was 7.7 mmol / g.

4) Acrylic resin (B) for the easy-adhesion layer: As the acrylic resin, a commercially available 25 mass% emulsion of an acrylic acid ester copolymer (“Movinyl (registered trademark) 7980” manufactured by Nichigo Movinyl Co., Ltd.) was prepared. The acid value (theoretical value) of the acrylic resin (B) was 4 mgKOH / g.

5) Urethane resin (C) for easy-adhesion layer: As a urethane resin, a commercially available polyester urethane resin dispersion (“Takelac (registered trademark) W605” manufactured by Mitsui Chemicals, Inc .; solid content: 30%) was prepared. The acid value of this urethane resin was 25 mgKOH / g, and the glass transition temperature (Tg) measured by DSC was 100 ° C. . The ratio of aromatic diisocyanate or araliphatic diisocyanate to the whole polyisocyanate component measured by 1H-NMR was 55 mol%.

6) Urethane resin (D) for protective layer ;: As a urethane resin, a commercially available dispersion of a metaxylylene group-containing urethane resin (“Takelac (registered trademark) WPB341” manufactured by Mitsui Chemicals, Inc .; solid content: 30%) was prepared. . The acid value of this urethane resin was 25 mgKOH / g, and the glass transition temperature (Tg) measured by DSC was 130 ° C. The ratio of aromatic diisocyanate or araliphatic diisocyanate to the total polyisocyanate component measured by ¹ H-NMR was 85 mol%.

7) Coating liquid 1 (coat 1) used for the easy-adhesion layer
Each material was mixed in the following blending ratio to prepare a coating liquid (resin composition for easy-adhesion layer).
Water 54.40 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

8) Coating liquid 2 (coat 2) used for the protective layer
The following coating materials were mixed to prepare coating liquid 2. Here, the mass ratio of the urethane resin (E) in terms of solid content is as shown in.
Water 60.00 mass%
Isopropanol 30.00 mass%
Urethane resin (D) 10.00 mass%

The method for producing the base layer film used in each example and comparative example will be described below.
<Production of base material layer film; A-1>
Using a single-screw extruder, 80% by mass of PBT resin and 20% by mass of PET resin were mixed, and silica particles having an average particle size of 2.4 μm as inert particles were used as silica concentration of 900 ppm with respect to the mixed resin. After being melted at 290 ° C., the melt line was introduced into a 12-element static mixer. Thus, the molten resin was divided and laminated to obtain a multi-layered melt made of the same raw material resin. A non-stretched sheet was obtained by casting from a T-die at 265 ° C. and closely contacting it with a cooling roll at 15 ° C. by an electrostatic contact method.
Then, it was roll-stretched 2.9 times in the MD direction at 60 ° C. After that, the longitudinally stretched film was forcibly cooled by a cooling roll set to a surface temperature of 25 ° C., then passed through a tenter and stretched 4.0 times in the TD direction at 90 ° C. for 3 seconds at 200 ° C. After performing the tension heat treatment and the relaxation treatment in the TD direction of 9% for 1 second, the grip portions at both ends were cut and removed by 10% to obtain a mill roll of a PBT film having a thickness of 15 μm. Table 1 shows film forming conditions, physical properties and evaluation results of the obtained film.
In the film forming process of the biaxially stretched film of the substrate layer film, the resin composition for easy-adhesion layer (coating liquid 1) was applied by the fountain bar coating method after stretching in the MD direction. Then, it was introduced into a tenter while being dried, stretched in the TD direction under the above-mentioned film forming conditions, heat-treated and relaxed to obtain a laminated film A1 in which an easily adhesive layer was formed on one surface of a PBT film having a thickness of 15 μm.

<Production of base material layer film; A-2>
In the method for producing the base material film A-1 described above, the discharge amount when casting the molten resin from the T-die was adjusted to obtain a PBT film having a thickness of 20 μm.
In the film forming process of the biaxially stretched film of the substrate layer film, the resin composition for easy-adhesion layer (coating liquid 1) was applied by the fountain bar coating method after stretching in the MD direction. Then, it was introduced into a tenter while being dried, and stretched in the TD direction, heat-treated and relaxed under the above-mentioned film forming conditions to obtain a laminated film A2 in which an easy-adhesion layer was formed on one surface of a PBT film having a thickness of 20 μm.

<Production of base material layer film; A-3>
Using a single-screw extruder, 80% by mass of PBT resin and 20% by mass of PET resin were mixed, and silica particles having an average particle size of 2.4 μm as inert particles were used as silica concentration of 900 ppm with respect to the mixed resin. After being melted at 290 ° C., the melt line was introduced into a 12-element static mixer. Thus, the molten resin was divided and laminated to obtain a multi-layered melt made of the same raw material resin. A non-stretched sheet was obtained by casting from a T-die at 265 ° C. and closely contacting it with a cooling roll at 15 ° C. by an electrostatic contact method.
Then, it was roll-stretched 3.8 times in the MD direction at 60 ° C. After that, the longitudinally stretched film was forcibly cooled by a cooling roll set to a surface temperature of 25 ° C., then passed through a tenter and stretched 4.0 times in the TD direction at 90 ° C. for 3 seconds at 210 ° C. After performing the tension heat treatment and the 5% TD direction relaxation treatment for 1 second, the grip portions at both ends were cut and removed by 10% to obtain a mill roll of a PBT film having a thickness of 15 μm. Table 1 shows film forming conditions, physical properties and evaluation results of the obtained film.
In the film forming process of the biaxially stretched film of the substrate layer film, the resin composition for easy-adhesion layer (coating liquid 1) was applied by the fountain bar coating method after stretching in the MD direction. Then, it was introduced into a tenter while being dried, stretched in the TD direction under the above-mentioned film forming conditions, heat-treated and relaxed to obtain a laminated film A1 in which an easily adhesive layer was formed on one surface of a PBT film having a thickness of 15 μm.

The method for forming the inorganic thin film layer in each of Examples and Comparative Examples will be described below.
<Composite oxide of silicon and aluminum oxide dioxide formation _{(SiO 2 / Al 2 O 3} ) inorganic thin layer M1>
As the inorganic thin film layer M1, a composite oxide layer of silicon dioxide and aluminum oxide was formed on the base material films A-1 to A-3 of the example by an electron beam evaporation method. As the vapor deposition source, particulate SiO ₂ (purity 99.9%) and A1 ₂ O ₃ (purity 99.9%) of about 3 mm to 5 mm were used. The film thickness of the inorganic thin film layer (SiO ₂ / A1 ₂ O ₃ composite oxide layer) in the film (inorganic thin film layer / easy-adhesion layer-containing film) thus obtained was 13 nm. The composition of this composite oxide layer was SiO ₂ / A1 ₂ O ₃ (mass ratio) = 60/40.

<Formation of Aluminum Oxide (Al ₂ O ₃ ) Inorganic Thin Film Layer M2>
As the inorganic thin film layer M2, aluminum oxide was vapor-deposited on the base material layer films A-1 and OPET of the comparative example. In the method of vapor-depositing aluminum oxide on a base film, the film is set on the unwinding side of a continuous vacuum vapor deposition machine and is run through a cooling metal drum to wind up the film. At this time, the continuous vacuum vapor deposition machine was depressurized to 10 ⁻⁴ Torr or less, and aluminum alumina crucible was charged with metallic aluminum having a purity of 99.99% from the lower part of the cooling drum to evaporate the metallic aluminum by heating and vaporize it. Oxygen was supplied to carry out an oxidation reaction to deposit and deposit on the film to form an aluminum oxide film having a thickness of 30 nm.

<Formation of protective layer>
The coating liquid 2 was applied on the inorganic thin film layer formed on the base material layer film by a wire bar coating method and dried at 200 ° C. for 15 seconds to obtain a protective layer. The coating amount after drying was 0.19 g / m ² (Dry).
As described above, a gas barrier laminate film having an easily adhesive layer / inorganic thin film layer / protective layer on the substrate layer film was produced.

<Formation of laminated film>
[Example 1]
On the above-prepared base film A-1, coat 1 as an easy-adhesion layer, M1 as an inorganic vapor deposition layer, and coat 2 as a protective layer were laminated in this order to produce a gas barrier film. On the protective layer side of the gas barrier film prepared here, an adhesive (“TM569” manufactured by Toyo Morton Co., Ltd.), a curing agent “CAT-10L”, and ethyl acetate 33.6: 4.0: 62.4 ( (Mass ratio) (blended) and a polyethylene film (“L4102” manufactured by Toyobo Co., Ltd.) having a thickness of 60 μm is attached as a sealant layer by a dry laminating method, and aging is performed at 40 ° C. for 4 days. The laminated film of Example 1 was obtained. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm.

[Example 2]
Lamination of Example 2 in the same manner as in Example 1 except that in the laminated film of Example 1 described above, A-3 was used as the base material and an LLDPE film (Evolew SP2020 made by Prime Polymer, thickness 130 μm) was used as the sealant layer. I got a film. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm.

[Example 3]
On the above-prepared base film A-1, coat 1 as an easy-adhesion layer, M1 as an inorganic vapor deposition layer, and coat 2 as a protective layer were laminated in this order to produce a gas barrier film. On the protective layer side of the gas barrier film, a urethane-based two-component curable adhesive (“Takelac (registered trademark) A525S” and “Takenate (registered trademark) A50” manufactured by Mitsui Chemicals, Inc. in a ratio of 13.5: 1 (mass ratio) is used. Example 3 by adhering a 70 μm thick CPP (“P1147” manufactured by Toyobo Co., Ltd.) as a heat-sealable resin layer by a dry laminating method using a blending ratio) and aging at 40 ° C. for 4 days. A laminated film of was obtained. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm.

[Example 4]
In the laminated film of Example 3 described above, a laminated film of Example 4 was obtained in the same manner as in Example 1 except that the base film was A-2. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm.

[Example 5]
On the base film A-1 obtained above, an aluminum foil (8079 material, thickness 7 μm) is used as a urethane two-component curing adhesive (“Takelac (registered trademark) A525S” and “Takenate” manufactured by Mitsui Chemicals, Inc. (Registered trademark) A50 "was blended in a ratio of 13.5: 1 (mass ratio)) to dry-laminate the substrate film / aluminum foil laminate.
Next, on the aluminum foil side of the base film / aluminum foil laminate obtained above, the same adhesive as above was used, and a CPP having a thickness of 50 μm as a heat-sealable resin layer (“P1147” manufactured by Toyobo Co., Ltd.). Were laminated and aged at 40 ° C. for 4 days to obtain a laminated film of Example 5. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm in all cases.

[Example 6]
The laminated film of Example 6 was the same as Example 5 except that the heat-sealing resin layer was an unstretched polypropylene film having a thickness of 60 μm (“P1147” manufactured by Toyobo Co., Ltd.). I got a film. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm in all cases.

[Comparative Example 1]
Comparative Example 1 was repeated in the same manner as in Example 1 except that the inorganic vapor deposition layer was M2 and the sealant layer was a polyethylene film having a thickness of 40 μm (“L4102” manufactured by Toyobo Co., Ltd.). A laminated film was obtained.

[Comparative Example 2]
In the laminated film of Comparative Example 1 described above, a laminated film of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that the substrate film was OPET having a thickness of 12 μm (“E5102” manufactured by Toyobo Co., Ltd.).

[Comparative Example 3]
As a base film, ONy having a thickness of 15 μm (“N1102” manufactured by Toyobo Co., Ltd.), an adhesive (“TM569” manufactured by Toyo Morton Co., Ltd.), a curing agent “CAT-10L”, and ethyl acetate 33.6: 4. A polyethylene film (“L4102” manufactured by Toyobo Co., Ltd.) having a thickness of 60 μm was stuck as a sealant layer by a dry lamination method using 0: 62.4 (mass ratio), and aged at 40 ° C. for 4 days. By performing the above, a laminated film of Comparative Example 3 was obtained. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm.

[Comparative Example 4]
As a base film, ONy having a thickness of 15 μm (“N1102” manufactured by Toyobo Co., Ltd.), an adhesive (“TM569” manufactured by Toyo Morton Co., Ltd.), a curing agent “CAT-10L”, and ethyl acetate 33.6: 4. A LLDPE film (Evolue SP2020 made by Prime Polymer, thickness 130 μm) as a sealant layer is stuck by a dry lamination method using 0: 62.4 (mass ratio), and aged at 40 ° C. for 4 days. Thereby, a laminated film of Comparative Example 4 was obtained. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm.

[Comparative Example 5]
In the laminated film of Comparative Example 2 described above, the urethane-based two-component curing adhesive (“Takelac (registered trademark) A525S” and “Takenate (registered trademark) A50” manufactured by Mitsui Chemicals, Inc. was used as a 13.5: 1 adhesive. (Blended in the ratio of (mass ratio)), and the heat-sealable resin layer was a non-stretched polypropylene film having a thickness of 70 μm (“P1147” manufactured by Toyobo Co., Ltd.) A laminated film was obtained.

[Comparative Example 6]
In the laminated film of Comparative Example 3 described above, the urethane-based two-component curable adhesive (“Takelac (registered trademark) A525S” and “Takenate (registered trademark) A50” manufactured by Mitsui Chemicals, Inc. was used as a 13.5: 1 adhesive. (Blended in the ratio of (mass ratio)), and the heat-sealable resin layer was a non-stretched polypropylene film having a thickness of 70 μm (“P1147” manufactured by Toyobo Co., Ltd.), and laminated in Comparative Example 6 in the same manner as Comparative Example. I got a film.

[Reference Example 1]
As a base film, OPET having a thickness of 12 μm (“E5102” manufactured by Toyobo Co., Ltd.) was used, and ONy having a thickness of 15 μm (“N1102” manufactured by Toyobo Co., Ltd.) was used as an adhesive (“TM569” manufactured by Toyo Morton Co., Ltd.). The curing agent "CAT-10L" and ethyl acetate were mixed at a ratio of 33.6: 4.0: 62.4 (mass ratio) were used for dry lamination to obtain an OPET / ONy laminated film.
On the ONy side of the OPET / ONy laminate obtained above, an adhesive (“TM569” manufactured by Toyo Morton Co., Ltd.), a curing agent “CAT-10L”, and ethyl acetate 33.6: 4.0: 62. 4 (mass ratio)), a polyethylene film having a thickness of 40 μm (“L4102” manufactured by Toyobo Co., Ltd.) was stuck as a sealant layer, and aged for 4 days at 40 ° C. A laminated film was obtained. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm.

[Reference example 2]
A laminated film of Reference Example 2 was obtained in the same manner as in Reference Example 1 except that the sealant layer in Reference Example 1 was an LLDPE film (Evolew SP2020 made by Prime Polymer, thickness 130 μm).

[Reference Example 3]
In the above-mentioned Reference Example 2, the urethane-based two-component curing adhesive (“Takelac (registered trademark) A525S” and “Takenate (registered trademark) A50” manufactured by Mitsui Chemicals, Inc. was used as a 13.5: 1 (mass ratio). )), And the heat-sealable resin layer was a non-stretched polypropylene film having a thickness of 70 μm (“P1147” manufactured by Toyobo Co., Ltd.), and the laminated film of Reference Example 3 was prepared in the same manner as in Reference Example 2. Obtained.

[Reference Example 4]
As a base film, OPET having a thickness of 12 μm (“E5102” manufactured by Toyobo Co., Ltd.) was used, and ONy having a thickness of 15 μm (“N1102” manufactured by Toyobo Co., Ltd.) was used as an adhesive (“TM569” manufactured by Toyo Morton Co., Ltd.). A curing agent "CAT-10L" and ethyl acetate were mixed at a ratio of 33.6: 4.0: 62.4 (mass ratio) were used for dry lamination to obtain an OPET / ONy laminate.
Then, on the ONy side of the OPET / ONy laminate obtained above, aluminum foil (8079 material, thickness 7 μm) was used as a urethane two-component curing adhesive (“Takelac (registered trademark) A525S” manufactured by Mitsui Chemicals, Inc.). "Takenate (registered trademark) A50" was dry-laminated using 13.5: 1 (mass ratio) to prepare an OPET / ONy / aluminum foil laminate.
Next, on the aluminum foil side of the OPET / ONy / aluminum foil laminate obtained above, the same adhesive as above was used, and a non-stretched polypropylene film having a thickness of 50 μm as a heat-sealable resin layer (manufactured by Toyobo Co., Ltd. P1147 ") was attached and aged at 40 ° C. for 4 days to obtain a laminated film of Reference Example 4. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm in all cases.

The evaluation results of the laminated films obtained in Examples, Comparative Examples and Reference Examples are shown in Table 1, Table 2 and Table 3.

 

 

 

 

 

 

As shown in Table 1, in the laminated films of Examples 1 to 6 obtained by the present invention, since the base film can be one layer, the packaging material can be reduced in weight and the piercing strength is excellent. It was possible to obtain 0.0 N or more, excellent pinhole resistance, and the standing pouch made from it was able to secure sufficient independence.

On the other hand, in Comparative Example 1, since the thickness of the laminated film and the numerical values of the loop stiffness were out of the range of the present invention, the prepared standing pouch was insufficient in self-supporting property.
In Comparative Example 2, since only the conventional OPET film was used as the base material layer, the piercing strength and the pinhole resistance were poor. Further, since the numerical value of the loop stiffness does not satisfy the range of the present invention, the self-reliance as a standing pouch was insufficient.
In Comparative Example 3, since only the conventional ONy was used as the base material layer, although the piercing strength and the pinhole resistance were good, the loop stiffness value did not satisfy the range of the present invention, so that it was used as a standing pouch. Was lacking in independence.
In Comparative Examples 4 and 6, since only the conventional ONy was used as the base material layer, the puncture strength and the pinhole resistance were good. Further, by increasing the thickness of the sealant layer, the numerical value of the loop stiffness was increased, and it had good self-supporting property. However, since the base film is different from that of the present invention, the piercing strength after the retort treatment was significantly reduced.
In Comparative Example 5, by increasing the thickness of the sealant layer, the value of loop stiffness was high and the self-supporting property of the standing pouch was improved, but since OPET was used as the base material layer, the piercing strength and pinhole resistance were improved. The result was inferior.

Reference Examples 1 to 4 show the evaluation results when OPET and ONy, which are excellent in impact resistance and puncture resistance and can withstand heat treatment such as retort treatment, are used as a substrate film by laminating them. It was Comparing the reference example with the example, the laminated film of the present invention of the example is equivalent to the laminated film using two layers of OPET and ONy as the substrate layer, though the substrate layer is one layer. Had performance.

According to the present invention, it is possible to reduce the amount of packaging material, it is excellent in bag puncture resistance, and it is possible to secure sufficient independence even when used as a standing pouch, suitable for liquid packaging such as retort foods. Laminated film can be obtained.
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a laminated film having excellent puncture strength, bag puncture resistance, and bending resistance even after subjected to moist heat treatment. Conventionally, a packaging bag such as a standing pouch, which was conventionally made of a laminated film using a base film obtained by laminating OPET and ONy, can be made of a laminated film made of a single layer of the base film. Widely applicable as.

Claims (10)

A laminated film comprising at least a base material layer and a sealant layer,
(A) the base material layer is a biaxially stretched polyester film having a thickness of 9 μm to 25 μm and containing 70% by mass or more of polybutylene terephthalate,
(B) The piercing strength of the laminated laminated film is 9.0 N or more,
(C) A laminated film characterized in that the numerical value X (mN / 25 mm) of loop stiffness of the laminated film is 80 or more, and (e) the total thickness is 59 to 160 μm. The laminated film according to claim 1, wherein an inorganic thin film layer is provided on at least one surface of the base material layer. The laminated film according to claim 2, wherein the inorganic thin film layer is a layer made of an oxide of silicon oxide and / or aluminum oxide. The laminated film according to claim 2 or 3, wherein an adhesive layer is provided between the base material layer and the inorganic thin film layer. The laminated film according to any one of claims 2 to 4, which has a protective layer on the inorganic thin film layer. A packaging bag made of the laminated film according to any one of claims 1 to 5. The packaging bag according to claim 6, which is used as a standing pouch. The packaging bag according to claim 7, wherein the content Y (g) of the standing pouch satisfies the following formula (1), where X is a numerical value of the loop stiffness of the laminated film.
1.8X ≤ Y ≤ 3.8X Formula (1) The packaging bag according to any one of claims 6 to 8, which is used for a retort. The packaging bag according to any one of claims 6 to 8, which is used for heating a microwave oven.

Images