JPWO2020031712A1 - Gas barrier laminated film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas barrier laminate film and a laminate laminate which have excellent gas barrier properties, bending resistance and bag breaking resistance even after subjected to moist heat treatment. A gas barrier laminate film comprising at least a base material layer/inorganic thin film layer/protective layer, which satisfies the following conditions (a) to (d). (A) The base material layer is made of a resin composition containing 60% by mass or more of a polybutylene terephthalate resin. (B) The puncture strength is 0.6 N/μm or more. (C) Thermal shrinkage MD=1 to 4%, TD=-1 to 3%. (D) The maximum dimensional change rate (Amax-Amin) in the MD direction is 2% or less in the dimensional variation curve obtained by increasing the temperature from 25°C to 160°C using TMA and then decreasing the temperature to 50°C. [Selection diagram] None

Description

The present invention relates to a laminated laminate used in the field of packaging foods, pharmaceuticals, industrial products and the like. More specifically, it is a laminated laminate comprising a gas barrier laminate film having an inorganic thin film layer and a protective layer in this order on a base material layer and a sealant layer, which is excellent in bag-breaking resistance and retort. The present invention relates to a laminated laminate having excellent gas barrier properties even when used in applications such as sterilization after severe wet heat treatment.

Packaging materials used for foods, pharmaceuticals, etc. should have a property of blocking gas such as oxygen and water vapor, that is, a gas barrier property, for the purpose of suppressing the oxidation of proteins and fats and oils, maintaining taste and freshness, and maintaining the efficacy of pharmaceuticals. It has been demanded. Further, a gas barrier material used for an electronic device such as a solar cell or an organic EL, an electronic component or the like requires a gas barrier property higher than that of a packaging material such as food.

Conventionally, in food applications that require the blocking of various gases such as water vapor and oxygen, on the surface of a base material film made of plastic, a metal thin film made of aluminum or the like, and an inorganic oxide such as silicon oxide or aluminum oxide. A gas-barrier laminated film having an inorganic thin film is generally used.

It has been known that the use of a biaxially stretched nylon film as the base material layer improves the pinhole resistance of the contents and prevents the contents from leaking when the bag is dropped. However, the biaxially stretched nylon film has a large dimensional change when it absorbs moisture, which causes it to curl due to moisture absorption during the processing process, or to deform due to shrinkage when subjected to severe treatment such as retort sterilization. was there.

On the other hand, a polyethylene terephthalate (hereinafter abbreviated as PET) film on which a thin film of an inorganic oxide such as silicon oxide, aluminum oxide, or a mixture thereof is formed is transparent and the contents can be confirmed. Widely used. (For example, Patent Document 1 and Patent Document 2)
PET film is excellent in heat resistance and dimensional stability and can be used even when subjected to a severe treatment such as retort sterilization, but since the PET film is brittle, a bag made of a laminated film using the PET film is There was a problem that the bag was torn or dropped when dropped and the contents packed in the bag leaked.

As a method for solving these problems, a layer having a biaxially stretched multilayer film obtained by biaxially stretching a multilayer film having a polyester resin layer and a polyamide resin layer is used as a base layer of a transparent gas barrier film. Therefore, a technique has been proposed in which a packaging material for boil treatment or retort treatment, which is inexpensive and excellent in low elution and transparency, can be obtained (for example, Patent Document 3).
Such a conventional technique has a problem in that it easily peels off at the interface between the polyester-based resin layer and the polyamide-based resin layer, so that the bag is broken when the bag is dropped and the contents easily leak.

A biaxially stretched PBT-based film comprising at least a polybutylene terephthalate (hereinafter abbreviated as PBT) resin or a polyester-based resin composition in which a PET resin is blended in an amount of 30% by weight or less with respect to a poly-PBT resin. It was known to be used for a base material layer (for example, Patent Document 4).
However, although such a conventional technique improves impact resistance, it also has insufficient gas barrier properties after being processed into a laminated film. Further, there is a problem in the gas barrier property after the retort treatment.

JP-A-6-278240 JP, 11-10725, A JP, 2013-154605, A JP, 2012-214248, A

The present invention has been made against the background of the problems of the related art. That is, on the substrate layer, a gas barrier laminate film having an inorganic thin film layer and a protective layer in this order and a laminate laminate comprising the sealant layer, excellent in bag breaking resistance, flex resistance, Further, it is to provide a gas barrier laminate film and a laminate laminate which have excellent gas barrier properties even when used in applications such as retort sterilization after severe moist heat treatment.

As a means for obtaining excellent gas barrier properties even when used in applications where it has excellent bag-breaking resistance and bending resistance and is subjected to severe moist heat treatment such as retort sterilization, it is possible to use an inorganic film on a PBT film. It was considered preferable to provide a thin film layer and a protective film.
As a method for industrially forming an inorganic thin film layer and a protective film on a film substrate layer, while unwinding a film roll to be a film substrate layer, a step of forming an inorganic thin film layer, a step of subsequently forming a protective film. It is preferable to provide. Particularly in the step of forming the protective film, after the applied coating film is heat-treated at a high temperature of several tens of degrees Celsius to 200° C. for the purpose of drying and curing the coating liquid containing the composition used for the protective film, The film is wound while applying a constant tension mainly in the flow direction.
However, since PBT has a lower glass transition temperature than PET, it has a property that the film is easily stretched when tension is applied at a high temperature. The present inventors obtained as a result of the film base material layer being stretched when the film base material layer is tensioned while being heated in the protective film forming step, and the inorganic thin film layer previously formed is cracked. It was found that the gas barrier property of the gas barrier film is lowered.

Therefore, the inventors of the present invention, in the case of laminating an inorganic thin film layer on a film base material layer containing PBT as a main component to form a gas barrier film, have a heat shrinkage rate and a temperature rising process of a PBT film used as a base material layer. By setting the dimensional change rate in the temperature lowering process within a specific range, it is difficult to deform against the tension applied in the protective film forming process and the heating temperature, and it is possible to suppress damage to the inorganic thin film layer, and to prevent retort sterilization. The inventors have found that good gas barrier properties can be maintained even after severe moist heat treatment, and have solved the above problems.

That is, the present invention has the following configurations. (1) A gas barrier laminated film, which is a laminated film composed of at least a base material layer/an inorganic thin film layer/a protective layer, and which satisfies the following conditions (a) to (d).
(A) The base material layer is made of a resin composition containing 60% by mass or more of a polybutylene terephthalate resin.
(B) The puncture strength is 0.6 N/μm or more.
(C) MD shrinkage at 150° C. is 1 to 4%, and TD shrinkage is -1 to 3%.
(D) Obtained by using a thermal mechanical analyzer to raise the initial load of 0.2 g from 25° C. to 160° C. at a temperature raising rate of 10° C./min, and then lowering the temperature to 50° C. at a temperature lowering rate of −10° C./min. In the MD dimensional variation curve, when the maximum value Amax (%) of the dimensional change rate with respect to the original film length in the temperature rising process and the minimum value Amin (%) of the dimensional change rate with respect to the original film length in the temperature decreasing process, The dimensional change rate (Amax-Amin) is 2% or less.
(2) The gas barrier laminate film according to (1), which has an easy-adhesion layer between the base material layer and the inorganic thin film layer.
(3) The gas barrier laminate film according to (1) or (2), wherein the inorganic thin film layer is a layer made of aluminum oxide or a composite oxide of silicon oxide and aluminum oxide.
(4) The gas barrier laminate film according to (2) or (3), wherein the easy-adhesion layer is made of a resin composition containing a resin having an oxazoline group. (5) The protective layer is aromatic. Alternatively, the gas barrier laminated film according to any one of (1) to (5), which is a urethane resin containing an araliphatic component.
(6) The gas barrier laminate film according to any one of (1) to (5), wherein the protective layer comprises at least a water-soluble polymer, a metal alkoxide, and a hydrolyzate thereof.
(7) The protective layer is formed on a gas barrier laminate film composed of a base material layer/inorganic thin film layer that satisfies the following condition (e), and the protective layer is formed on any one of (1) to (5). A method for producing a gas barrier laminate film.
(E) Using a thermal mechanical analyzer, the gas barrier laminate film before formation of the protective film was heated from 25°C to 160°C at an initial load of 0.2 g at a temperature rising rate of 10°C/minute, and then the temperature lowering rate was -10°C/ Dimensional change curve obtained by lowering the temperature to 50° C. in minutes, the maximum value Amax (%) of the dimensional change rate with respect to the film original length in the temperature rising process, and the minimum value Amin (%) of the dimensional change rate with respect to the film original length in the temperature decreasing process In that case, the maximum dimensional change rate in the MD direction (Amax-Amin) is 0.5 to 3% or less.
(8) Oxygen permeability after retort treatment for 30 minutes at 120° C. comprising the gas barrier laminate film according to any one of (1) to (5) and a sealant layer is 15 ml/m ² ·day·MPa or less, A laminated laminate having a water vapor permeability of 2 g/m ² ·day or less.
(9) The laminated laminate according to (6), wherein the biaxially stretched polyethylene terephthalate film is laminated on the surface of the gas barrier laminated film on the base material layer side.
(10) A packaging bag comprising the laminate laminate according to (7) or (8).
(11) The packaging bag according to (9), which is used for a retort.
(12) The packaging bag according to (9), which is used for heating a microwave oven.
(13) The packaging bag according to (9), which is used for vacuum packaging.

The inventors of the present invention have made such a gas barrier having excellent bag-breaking resistance and bending resistance, and having excellent gas barrier properties even when used in applications such as retort sterilization after severe wet heat treatment. It has become possible to provide a laminated film and a laminated laminate comprising the same and a sealant layer.

Measurement example of maximum dimensional change rate in MD direction

Hereinafter, the present invention will be described in detail.
[Base material layer]
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 properties 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 the dicarboxylic acid component, more preferably 95 mol% or more, and further preferably 98 mol% or more. It is preferably 100 mol %. The glycol component is preferably 1,4-butanediol in an amount of 90 mol% or more, more preferably 95 mol% or more, still more preferably 97 mol% or more, and most preferably 1,4-butane at the time of polymerization. It means that it does not contain other than by-products generated 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 PET, polyethylene naphthalate, polybutylene naphthalate and polypropylene terephthalate, and isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid and sebacic acid. PBT resin copolymerized with at least one dicarboxylic acid selected from the group consisting of, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6 -PBT resin in which at least one diol component selected from the group consisting of hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol and polycarbonate diol is copolymerized.

The upper limit of the addition amount of the polyester resin other than PBT is 40% by mass or less, and 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 reduced. 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 breakage 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-forming property 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 kind of the 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, still more 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.

In the film of the base material layer in the present invention, it is preferable that the resin having the same composition is present over the entire area of the film. In the substrate layer film of the present invention, the lower limit of the thickness of the substrate layer film 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 material layer 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 molten resin sheet contacting the rotating metal roll, by applying a voltage to the electrode installed near the surface opposite to 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 the molten polyester resin is cast 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 layered and cast, and the cooling roll temperature is lowered.

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, 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 multi-layering is performed with a static mixer, the theoretical number of layers can be adjusted by selecting the number of elements of 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 with the number of elements n, the theoretical fluid number N=(2 to the n-th power) of the fluid fluid is formed.

The upper limit of the temperature of the cooling roll when the molten polyester resin is extruded and cast on the 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 lower 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 Material Layer]
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 is unlikely to occur. In addition, 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, straight-line tearability in the vertical direction is improved. Further, the effect of improving the mechanical strength and thickness unevenness is saturated in this range.

Further, in order to keep the maximum dimensional change rate of the laminated film within the range of the present invention, it is preferable to relax the film in the MD direction (longitudinal direction) after the longitudinal stretching. By relaxing the film in the MD direction after the longitudinal stretching, the residual stress in the MD direction of the film generated by the longitudinal stretching can be removed and the shrinkage rate can be reduced. Further, the relaxation in the MD direction can reduce the bowing phenomenon that occurs in the tenter. Furthermore, since the oriented and crystallized components of the film remain oriented, the dimensional change of the film can be reduced while maintaining the piercing strength of the film. The relaxation rate (relaxation rate) in the MD direction is preferably 0% or more and 10% or less. The upper limit of the relaxation rate in the longitudinal direction depends on the raw material used and the longitudinal stretching conditions, and the relaxation cannot be carried out beyond this. The maximum relaxation rate in the MD is about 20%.

The relaxation in the MD direction can be carried out by heating the longitudinally stretched film at a temperature of 65° C. to 100° C. or less and adjusting the speed difference of the rolls. As the heating means, any of rolls, near infrared rays, far infrared rays, hot air heaters and the like can be used. Further, the relaxation in the MD direction may be performed not only immediately after the longitudinal stretching but also in the lateral stretching (including the preheating zone) or the final heat treatment by narrowing the clip interval in the MD direction. In this case, both ends in the film width direction are also relaxed in the longitudinal direction, so that bowing distortion is reduced. After relaxing in the MD direction, it is preferable to cool the film once, and it is preferable to cool it with a cooling roll having a surface temperature of 20 to 40°C.

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. 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. Even if it is larger than 5.0 times, the effect of improving the mechanical strength and the thickness unevenness is saturated, and the breakage of the film tends to increase.

[Heat setting step in base material layer 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.

[Heat relaxation part process in base material layer production]
The lower limit of the relaxation rate in the heat relaxation section process 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, slack of the film is less likely to occur and uneven thickness is less likely to occur.

[Cooling process in base material layer production]
In the cooling step after performing the relaxation in the heat 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 film edge after passing through the cooling step exceeds 80° C., the edge 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 edge 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 of 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 edge of the film.

The lower limit of the orientation degree (ΔNx) in the MD direction of the film of the base material layer in the present invention is preferably 0.04, more preferably 0.045, and further preferably 0.05. Since the orientation is weak when it is less than the above, sufficient impact strength as a base layer film cannot be obtained, and not only bag breaking resistance may decrease, but also an inorganic thin film layer and a protective layer on the base layer film. When it is provided as a laminated film, it easily expands due to the tension and temperature applied during the formation of the protective film, and the inorganic thin film layer is cracked, so that the gas barrier property may deteriorate.

The upper limit of the degree of orientation (ΔNx) in the MD direction of the substrate layer 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 are more preferable. The degree of orientation (ΔNx) in the MD direction is obtained 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, and calculating ΔNx=Nx−(Ny+Nz)/2. Calculated by the formula.

The upper limit of the haze per film thickness of the base material layer 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.

Further, a layer of another material may be laminated on the base film in the present invention, and as a method thereof, the base film may be attached after being produced or may be attached during film formation.

[Easy adhesion layer and method for forming the same]
In the gas barrier laminated film of the present invention, an easy-adhesion layer can be provided between the base layer film and the inorganic thin film layer for the purpose of ensuring gas barrier properties and laminate strength after retort treatment. As the easy-adhesion layer provided between the base layer film and the inorganic thin film layer, urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based resins, epoxy-based, isocyanate-based, Examples include those to which a curing agent such as a melamine type is added. 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, an isocyanate group and the like. The addition of the silane coupling agent further improves the laminate strength after the retort treatment.

Among the resin compositions used for the easily adhesive 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, thus showing a strong adhesion to the inorganic thin film layer. .. Further, 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 cited 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 fed to a stretching process in the perpendicular direction. It is preferable to dry in the preheating zone or the stretching zone of the stretching step, and in such a case, it is usually preferable to set the temperature to about 50 to 250°C.

[Inorganic thin film layer and method for forming the same]
The inorganic thin film layer in the gas barrier laminate film of the present invention and the method for forming the same 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 form 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 such that Al is in the range of 20 to 70 mass% in terms of 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 be hard, and the film may be destroyed during secondary processing such as printing or laminating, and the gas barrier property may be deteriorated. Note that the silicon oxide here is SiO or various silicon oxide or mixtures thereof such as SiO2, and aluminum oxide, an AlO or A1 various aluminum oxides such as ₂ O ₃ or mixtures 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. However, 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 is a known vapor deposition method such as a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a chemical vapor deposition method (CVD method). The law 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 SiO2 and A1 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 the vapor deposition raw material, and 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, water vapor, or the like as the reaction gas, or employ 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 vapor deposition target, the heating/cooling, and the like can be similarly changed when the sputtering method or the CVD method is adopted.

In the present invention, the characteristics of the gas barrier laminate film before the formation of the protective film in which the inorganic thin film layer is laminated on the base material layer are as follows: initial load: 0.2 g, temperature increase rate: 10° C./min, 25° C., using a thermal mechanical analyzer. To 160° C. and then to 50° C. at a temperature lowering rate of −10° C./min. It is preferable that the maximum dimensional change rate in the MD direction (Amax-Amin) is 0.5 to 3% or less, where Amin (%) is the minimum dimensional change rate with respect to the original film length.
In the above measurement, a large dimensional change rate in the temperature rising process indicates that it is easily stretched when heated, and a large dimensional change rate in the temperature lowering process causes shrinkage in the cooling process after heating. , Indicates that the dimensions change. For this reason, the fact that the maximum dimensional change rate represented above is large indicates that the size increases or decreases when the protective film is formed or when food is heated or cooled in a retort process or the like.

The upper limit of the maximum dimensional change rate represented above is preferably 2% or less, more preferably 1.8% or less, and most preferably 1.6% or less. If the maximum dimensional change rate exceeds 2%, the gas barrier property may be damaged and the gas barrier property may be deteriorated after the food product using the laminate laminate as a packaging bag is subjected to the retort sterilization treatment.

[Protective layer and method for forming the same]
The protective layer in the gas barrier laminate film of the present invention and the method for forming the protective layer will be described.
The gas barrier laminate film of the present invention has a protective layer on the inorganic thin film layer. For example, in the case where the inorganic thin film layer is a metal oxide layer, the 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 metal oxide layer, the resin in the protective layer resin composition penetrates into the defective portion of the metal oxide layer, As a result, the effect of stabilizing the gas barrier property can be obtained. In addition, by using a material having a gas barrier property also for the protective layer itself, the gas barrier performance of the gas barrier 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. The thing which added hardening agents, such as a system hardening agent, is mentioned. 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.
Further, as the protective layer, a layer in which the protective layer comprises at least a water-soluble polymer, a metal alkoxide and a hydrolyzate thereof is also preferable.

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 an amorphous portion, so that it is possible to suppress damage to the inorganic thin film layer even when a bending load is applied. It is preferable because it is possible.
The acid value of the urethane resin is preferably within 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 preferably has a glass transition temperature (Tg) of 80° C. or higher, more preferably 90° C. or higher. By setting the Tg to 80° C. or higher, swelling of the protective layer due to molecular motion in the wet heat treatment process (temperature increase-heat retention-temperature decrease) can be reduced.

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 urethane bonds 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 the aromatic diisocyanate or the araliphatic diisocyanate in the urethane resin is preferably in the range of 50 to 100 mol% in 100 mol% of the polyisocyanate component. The proportion of the total amount of the aromatic diisocyanate or the 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.

From the viewpoint of improving the affinity with the inorganic thin film layer, the urethane resin preferably has a carboxylic acid group (carboxyl group). 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 or 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 Examples include N-dialkylalkanolamines such as -alkylmorpholines, N-dimethylethanolamine, and N-diethylethanolamine. These may be used alone or in combination of two or more.

As described above, it is also preferable that the protective layer is composed of at least a water-soluble polymer, a metal alkoxide and a hydrolyzate thereof.
As the metal alkoxide used for forming the protective layer in the present invention, conventionally known ones can be used. For example, the protective layer in the present invention is an aqueous solution or water and alcohol containing a water-soluble polymer having a hydroxyl group and one or more metal alkoxides and/or metal alkoxide hydrolysates as described in JP-A 2007-196550. It can be obtained by coating the inorganic thin film layer side of a film obtained by laminating an inorganic thin film layer on a substrate film with a coating agent using the mixed solution of as a solvent to form a thin film and heating and drying.

The thickness of the protective layer in the present invention is not particularly limited, but if the thickness after heating and drying is less than 0.01 μm, it becomes difficult to obtain a uniform thin film layer, and sufficient gas barrier properties cannot be obtained. There are cases. If the thickness exceeds 50 μm, cracks are likely to occur in the thin film layer. Therefore, the thickness of the protective layer is preferably 0.01 to 50 μm, more preferably 0.1 to 10 μm.

As a method for forming the protective layer, dipping method, roll coating method, gravure coating method, reverse coating method, air knife coating method, comma coating method, die coating method, screen printing method, spray coating method, gravure offset printing, etc. should be adopted. You can

[Gas barrier laminated film (base material layer/inorganic thin film layer/protective layer)]
The upper limit of the heat shrinkage ratio after heating at 150° C. for 15 minutes in the MD direction (longitudinal stretching direction) of the gas barrier laminate film of the present invention is preferably 4.0%, more preferably 3.0%, and It is preferably 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 the gas barrier property may deteriorate, and printing etc. Pitch deviation may occur due to dimensional changes during processing.

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

The upper limit of the heat shrinkage rate after heating at 150° C. for 15 minutes in the TD direction (transverse stretching direction) of the gas barrier laminate film of the present invention is preferably 3.0%, more preferably 2.0%. More preferably, it is 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 the gas barrier property may deteriorate, and printing etc. Pitch deviation may occur due to dimensional changes during processing.

The lower limit of the heat shrinkage ratio after heating at 150° C. for 15 minutes in the TD direction of the gas barrier laminate film of the present invention is preferably −1.0%. If it is less than the above, the improvement effect cannot be obtained any more. Also, it may be mechanically brittle.

The gas barrier laminate film after the formation of the protective layer of the present invention was heated from 25°C to 160°C at an initial load of 0.2 g at a temperature rising rate of 10°C/minute using a thermal mechanical analyzer, and then the temperature lowering rate was -10°C. In the dimensional variation curve obtained by lowering the temperature to 50° C./min, the maximum value Amax (%) of the dimensional change rate with respect to the film original length in the temperature raising process, the minimum value Amin of the dimensional change rate with respect to the film original length in the temperature decreasing process (%), the maximum dimensional change rate (Amax-Amin) in the MD direction is 2% or less.
In the above measurement, a large dimensional change rate in the temperature rising process indicates that it is easily stretched when heated, and a large dimensional change rate in the temperature lowering process causes shrinkage in the cooling process after heating. , Indicates that the dimensions change. For this reason, a large maximum dimensional change rate represented above indicates that the increase or decrease in the size when the protective film forming step during gas barrier film production or when heating or cooling food by retort treatment or the like becomes large. ing.

The upper limit of the maximum dimensional change rate expressed above is preferably 2% or less, more preferably 1.8% or less, and most preferably 1.6% or less. If the maximum dimensional change rate exceeds 2%, the gas barrier property may be damaged and the gas barrier property may be deteriorated after the food product using the laminate laminate as a packaging bag is subjected to the retort sterilization treatment.

The lower limit of the puncture strength of the gas barrier laminate film of the present invention is 0.6 N/μm. When it is 0.6 N/μm or more, the strength is sufficient when it is used as a bag. The upper limit of the puncture strength of the gas barrier laminate film of the present invention is not particularly limited, but is preferably 1.5 N/μm, more preferably 1.0 N/μm, and further preferably 0.74 N/μm. The upper limit of the puncture strength is to keep balance with other properties such as the waist strength of the film.

[Laminate Laminate and Forming Method Thereof]
When the laminated film of the present invention is used as a packaging material, it is preferable to form a heat-sealable resin layer called a sealant. The heat-sealable resin layer is usually provided on the upper side of the inorganic thin film layer, but may be provided on the outer side of the substrate layer film (the surface opposite to the inorganic thin film layer side). The heat-sealable resin layer is usually formed by an extrusion laminating method or a dry laminating method. The thermoplastic polymer that forms the heat-sealable resin layer may be any polymer that can sufficiently exhibit sealant adhesiveness, such as polyethylene resins such as HDPE, LDPE and LLDPE, polypropylene resin, ethylene-vinyl acetate copolymer. , Ethylene-α-olefin random copolymer, ionomer resin and the like can be used.

Furthermore, the laminated laminate of the present invention may have at least one or more printed layers and/or other plastic base materials and/or paper base materials 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 known antistatic agents, light blocking agents, UV absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, cross-linking agents, anti-blocking agents, antioxidants, etc. The additive may be included. The printing method for providing the printing layer is not particularly limited, and a known printing method such as an offset printing method, a gravure printing method, or 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.

From the above, the laminated laminate of the present invention is excellent in bag-breaking resistance and bending resistance, and can be used before and after bag-making processing and after bag-making processing for packaging of hard contents such as dry matter packaging, and retort. It has an excellent gas barrier property even when it is used in applications such as sterilization after severe moist heat treatment.

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]
It was measured using a dial gauge in accordance with JIS K7130-1999 A method.

[Heat Shrinkage of Gas Barrier Laminated Film]
The heat shrinkage of the polyester film was measured by the dimensional change test method described in JIS-C-2151-2006.21, except that the test temperature was 150° C. and the heating time was 15 minutes. The test piece was used as described in 21.1(a).

[Maximum dimensional change in MD direction of gas barrier laminated film before and after formation of protective layer]
Regarding the gas barrier laminate film before forming the protective layer and the gas barrier laminate film after forming the protective layer, the temperature was raised from room temperature to 160° C. using a thermal mechanical analyzer (TMA) manufactured by Shimadzu Corporation, and then from 160° C. to 50° C. The temperature was lowered to 100° C. and the dimensional change of the laminated film was measured. However, the temperature rising/falling rate was 10° C./min, the width of the measurement sample was 4 mm, the length of the measurement sample was 10 mm, and the initial load was 0.2 g. From the obtained temperature-dimensional change curve, the maximum value Amax (%) of the dimensional change rate with respect to the original film length in the temperature rising process and the minimum value Amin (%) of the dimensional change rate with respect to the original film length in the temperature decreasing process were read, and MD was read. The maximum dimensional change rate (Amax-Amin) in the direction was calculated.

[Production of laminated laminate]
On the protective layer side of the gas barrier laminate films shown in Examples 1 to 7 and Comparative Examples 1 to 4 described below, a urethane-based two-component curing adhesive (“Takelac (registered trademark) A525S” and “Takenate” manufactured by Mitsui Chemicals, Inc. (Registered trademark) A50" is blended in a ratio of 13.5:1 (mass ratio) by a dry lamination method as a heat-sealable resin layer having a thickness of 70 μm of an unstretched polypropylene film (“P1147 manufactured by Toyobo Co., Ltd.”). ]) was adhered and aged at 40° C. for 4 days to obtain a laminated laminate for evaluation. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was 4 μm.

[Pinhole resistance of laminate]
The above laminated laminate 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%. 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 circumference of a disk-shaped fixed head of 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 The other end of was fixed to the outer periphery 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 that face each other in parallel, and then is rotated 6.4 cm (without rotating). 2.5-inch) Straight running, 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 the portion of 17.8 cm (7 inches) x 27.9 cm (11 inches) excluding the portion fixed to the outer circumference of the fixed head and the movable head of the tested film was measured (ie, The number of pinholes per 497 cm ² (77 square inches) was measured).

[Bag resistance of laminated laminate]
Cut the above-mentioned laminated laminate into a size of 15 cm square, stack two sheets so that the sealant is on the inside, and heat-seal the three sides at a seal temperature of 160°C and a seal width of 1.0 cm. A 13-cm three-sided sealed bag was obtained. After filling the obtained three-way sealed bag with 250 mL of water, the mouth of the fourth side was closed by heat sealing to prepare a water-filled four-way sealed bag. The obtained four-side sealed bag was dropped onto a concrete plate from a position of 100 cm in height in an environment of room temperature of 5° C. and relative humidity of 35%, and the number of drops until breakage or pinholes was counted.

[Oxygen permeability (OTR) of laminated laminate]
An oxygen permeability measuring device (“OX-TRAN 2/20” manufactured by MOCON Co., Ltd.) was used for the laminated laminate described above in accordance with the electrolytic sensor method (Appendix A) of JIS-K7126-2, and the temperature was 23. The oxygen permeability in the normal state was measured under an atmosphere of °C and a relative humidity of 65%. The oxygen permeability was measured in the direction in which oxygen permeated from the substrate layer film side to the sealant side.

[Oxygen Permeability (OTR) of Laminated Laminate after Retort]
The above-mentioned laminated laminate is subjected to wet heat treatment in hot water at 130° C. for 30 minutes, dried at 40° C. for 1 day (24 hours), and the obtained laminated laminate after the heat treatment is as described above. Similarly, the oxygen permeability was measured.

[Water vapor permeability (WVTR) of laminated laminate]
For the above-mentioned laminated laminate, in accordance with JIS-K7129-1992 B method, using a water vapor permeability measuring device (“PERMATRAN-W1A” manufactured by MOCON), at a temperature of 40° C. and an atmosphere of relative humidity of 90 RH%. The water vapor permeability in the normal state was measured. The water vapor permeability was measured in the direction in which water vapor permeates from the base material layer film side to the sealant side.

[Water vapor permeability (WVTR) of laminated laminate after retort]
The above-mentioned laminated laminate is subjected to wet heat treatment in hot water at 130° C. for 30 minutes, dried at 40° C. for 1 day (24 hours), and the obtained laminated laminate after the heat treatment is as described above. Similarly, the water vapor permeability was measured.

The details of the raw material resins and coating liquids used in the present examples and comparative examples will be described below.
1) PBT resin: 1100-211XG (CHANG CHUN PLASTICS CO., LTD., intrinsic viscosity 1.28 dl/g) was used as the PBT resin used in the film production of base material layers A1 to A11 described later.
2) PET resin: A PET resin manufactured by Toyobo Co., Ltd. having an intrinsic viscosity of 0.62 dl/g was used as the PET resin used in the film formation of the substrate layer films A1 to A11 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 ester copolymer (“Movinyl (registered trademark) 7980” manufactured by Nichigo Movinyl Co., Ltd.) was prepared. The acid value (theoretical value) of this acrylic resin (B) was 4 mgKOH/g.

5) Urethane resin (C) for the easy-adhesion layer: As the 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 total 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; 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. Moreover, the ratio of the aromatic diisocyanate or the araliphatic diisocyanate to the whole polyisocyanate component measured by 1 H-NMR was 85 mol %.

7) Coating liquid 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 mass%

8) Coating liquid 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%

7) Coating liquid 3 used for the protective layer
The following coating agents 1 to 3 were mixed to prepare a coating liquid 3.
<Coating 1>
Hydrochloric acid solution having a solid content of 5% by mass (SiO2 conversion) obtained by adding hydrochloric acid (0.1N) 72 to 18 g of tetraethoxysilane and 10 g of methanol and stirring for 20 minutes for hydrolysis.
<Coating agent 2>
5% by mass water/methanol solution of polyvinyl alcohol (water/methanol mass ratio=95/5).
<Coating agent 3>
Hydrochloric acid (1N) was gradually added to β-(3,4 epoxycyclohexyl)trimethoxysilane and isopropyl alcohol (IPA solution), and the mixture was stirred for 30 minutes for hydrolysis, and then hydrolyzed with water/IPA=1/1 solution. And the solid content was adjusted to 5% by mass (converted to R2Si(OH)3).

The method for producing the base layer film used in each example and comparative example will be described below.
<Production of Base Layer Film; Examples 1-1 and 1-2>
Using a uniaxial extruder, a mixture of 80% by mass of polybutylene terephthalate resin and 20% by mass of polyethylene terephthalate resin was used, and silica particles having an average particle diameter of 2.4 μm as inert particles were used as silica concentration 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 polybutylene terephthalate melt was divided and laminated to obtain a multi-layer melt made of the same raw material. An unstretched sheet was obtained by casting from a T-die of 265° C. and closely contacting it with a cooling roll of 15° C. by an electrostatic contact method.
Then, it was roll-stretched 2.9 times in the MD direction at 60°C. The film immediately after longitudinal stretching was passed through a heating furnace set at 80° C. with a hot air heater, and 5% relaxation treatment was performed in the MD direction by utilizing the speed difference between the rolls at the inlet and outlet of the heating furnace. Then, the longitudinally stretched film was forcibly cooled by a cooling roll set to a surface temperature of 25° C., and then stretched through a tenter at 90° C. in the TD direction by 4.0 times, and at 200° C. for 3 seconds. After performing the heat treatment for tension 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 base 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 drying, and the solvent was volatilized and dried at a preheating temperature of 70°C. Then, stretching, heat treatment and relaxation were carried out in the TD direction under the film forming conditions shown in Tables 1 and 2 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; Examples 1-2 to 1-7, Comparative examples 1-1 to 1-4 and Examples 2-2 to 2-7, Comparative examples 2-1 to 2-4>
Substrate layer films A2 to A11 were produced in the same manner as the substrate layer film 1 except that the MD stretching ratio, MD relaxation rate, and TD direction relaxation rate were changed to the conditions shown in Tables 1 and 2.

The method for forming the inorganic thin film layer in each of Examples and Comparative Examples will be described below.
<Formation of Aluminum Oxide (A1 ₂ O ₃ ) Inorganic Thin Film Layer>
As the inorganic thin film layer M1, aluminum oxide was vapor-deposited on the base material layer films A1 to A5 of the example and the base material layer films A8 to 11 of the comparative example. In the method of vapor-depositing aluminum oxide on the 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 decompressed to 10 ⁻⁴ Torr or less, aluminum alumina crucible was charged with aluminum with a purity of 99.99% from the lower part of the cooling drum, and the aluminum metal was heated and vaporized. 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.

<Composite oxide of aluminum oxide and silicon dioxide _{(SiO 2 / A1 2 O 3} ) Formation of inorganic thin layer>
As the inorganic thin film layer M2, a composite oxide layer of silicon dioxide and aluminum oxide was formed on the base material films A6 and A7 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 complex 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 protective layer 1>
The coating liquid 2 was applied on the inorganic thin film layers formed on the base material layer films A1 to A11 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 0.190 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 protective layer 2>
Coating in which coating material 1, coating material 2 and coating material 3 are mixed on the inorganic thin film layers formed on the base material layer films A1 to A11 so that the compounding ratio (% by mass) is 70/20/10. The engineering liquid 3 was dried at 200° C. for 15 seconds to form a protective layer having a coating amount of 0.190 g/m ² (Dry) after drying.
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.

Tables 1 and 2 show the evaluation results of the gas barrier laminate films obtained in Examples and Comparative Examples.

As shown in Table 1 and Table 2, the gas barrier laminate film obtained by the present invention has the maximum dimensional change as seen in Examples 1-1 to 1-7 and Examples 2-1 to 2-7. By setting the rate within a predetermined range, the inorganic thin film layer is not damaged by the formation of the protective film, good gas barrier properties can be expressed, and even after the retort treatment, there is little dimensional change in the heating-cooling process. Therefore, it can be confirmed that the damage to the gas barrier layer is reduced and the good gas barrier property can be maintained. Furthermore, since it is excellent in bag-breaking resistance and bending pinhole resistance, it can be suitably used as a retort packaging material.

On the other hand, in Comparative Examples 1-1 and 2-1, since the maximum dimensional change rate and the thermal shrinkage rate were large, the gas barrier property after the retort treatment was poor.
In Comparative Examples 1-2 and 2-2, as a result of reducing the heat shrinkage rate only at the heat treatment temperature after transverse stretching as conventionally performed, the piercing strength and the bag-breaking resistance were poor.
In Comparative Examples 1-3 and 2-3, the relaxation rate in the MD direction was too high, and the maximum dimensional change rate and the heat shrinkage rate were too small. As a result, the inorganic thin film layer was damaged during the formation of the protective film, and the normal state was maintained. Had poor gas barrier properties.
In Comparative Examples 1-4 and 2-4, since the ratio of PBT was small, even if the gas barrier property was good, the puncture strength and bag-breaking resistance were poor.

ADVANTAGE OF THE INVENTION According to this invention, it is excellent in gas barrier property, dimensional stability, workability, bending resistance, and bag-breaking resistance, and is also an excellent gas barrier even in applications where severe moist heat treatment such as retort sterilization is performed. It is possible to obtain a gas barrier laminate film having properties and a laminate laminate using the same.
According to the present invention, a gas barrier laminate film having excellent gas barrier properties, bag breakage resistance, and flex resistance, and a laminate laminate using the same, are provided not only in a normal state but also after moist heat treatment. We were able to. Such a gas-barrier laminated film has the advantages that it is easy to manufacture, is excellent in economic efficiency and production stability, and can easily obtain uniform properties. Therefore, such a gas-barrier laminated film is widely applied as a food packaging material. As it can be done, it is expected to make a great contribution to the industrial world. Further, it can be widely used for packaging applications such as pharmaceuticals and industrial products, and industrial applications such as solar cells, electronic papers, organic EL devices, and semiconductor devices.

Claims (13)

A laminated film comprising at least a base material layer/inorganic thin film layer/protective layer, which satisfies the following conditions (a) to (d):
(A) The base material layer is made of a resin composition containing 60% by mass or more of a polybutylene terephthalate resin.
(B) The puncture strength is 0.6 N/μm or more.
(C) MD shrinkage at 150° C. is 1 to 4%, and TD shrinkage is -1 to 3%.
(D) Obtained by using a thermal mechanical analyzer to raise the initial load of 0.2 g from 25° C. to 160° C. at a temperature raising rate of 10° C./min, and then lowering the temperature to 50° C. at a temperature lowering rate of −10° C./min. In the MD dimensional variation curve, the maximum value of the dimensional change rate Amax (%) with respect to the film original length in the temperature rising process and the minimum value Amin (%) of the dimensional change rate with respect to the film original length in the temperature decreasing process are The dimensional change rate (Amax-Amin) is 2% or less. The gas barrier laminate film according to claim 1, comprising an easy-adhesion layer between the base material layer and the inorganic thin film layer. The gas barrier laminate film according to claim 1, wherein the inorganic thin film layer is a layer formed of aluminum oxide or a composite oxide of silicon oxide and aluminum oxide. The gas barrier laminate film according to claim 2 or 3, wherein the easy-adhesion layer is made of a resin composition containing a resin having an oxazoline group. The gas barrier laminate film according to any one of claims 1 to 5, wherein the protective layer is a urethane resin containing an aromatic or araliphatic component. The gas barrier laminate film according to any one of claims 1 to 5, wherein the protective layer comprises at least a water-soluble polymer, a metal alkoxide, and a hydrolyzate thereof. A protective layer is formed on a gas barrier laminate film composed of a base material layer/inorganic thin film layer satisfying the following condition (e), and the gas barrier laminate film according to any one of claims 1 to 5, wherein: Production method.
(E) Using a thermal mechanical analyzer, the gas barrier laminate film before formation of the protective film was heated from 25°C to 160°C at an initial load of 0.2 g at a temperature rising rate of 10°C/minute, and then the temperature lowering rate was -10°C/ Dimensional change curve obtained by lowering the temperature to 50° C. in minutes, the maximum value Amax (%) of the dimensional change rate with respect to the film original length in the temperature rising process, the minimum value Amin (%) of the dimensional change rate with respect to the film original length in the temperature decreasing process In that case, the maximum dimensional change rate in the MD direction (Amax-Amin) is 0.5 to 3% or less. Oxygen permeability after retort treatment at 120° C. for 30 minutes consisting of at least the gas barrier laminate film according to any one of claims 1 to 5 and sealant layer is 15 ml/m ² ·day·MPa or less, and water vapor permeability is 2 g. /M ² ·day or less laminate laminate. The laminated laminate according to claim 6, wherein a biaxially stretched polyethylene terephthalate film is laminated on the surface of the gas barrier laminated film on the side of the base material layer. A packaging bag comprising the laminated laminate according to claim 7. The packaging bag according to claim 9, which is used for a retort. The packaging bag according to claim 9, which is used for heating a microwave oven. The packaging bag according to claim 9, which is used for vacuum packaging.