JP6927336B2 - Gas barrier laminated film and its manufacturing method - Google Patents

Description

The present invention relates to a laminated laminate used in the packaging field of foods, pharmaceuticals, industrial products and the like. More specifically, it is a laminated laminate composed of a gas barrier laminated 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 that are subjected to severe moist heat treatment such as sterilization.

Packaging materials used in foods, pharmaceuticals, etc. must have the property of blocking gases such as oxygen and water vapor, that is, gas barrier properties, in order to suppress the oxidation of proteins and fats and oils, maintain the taste and freshness, and maintain the efficacy of pharmaceuticals. It has been demanded. Further, gas barrier materials used for electronic devices such as solar cells and organic EL, electronic parts, etc. require higher gas barrier properties than packaging materials such as foods.

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

It has been known that by using a biaxially stretched nylon film as a base material layer, pinhole resistance due to the contents is improved and leakage of the contents when the bag is dropped is eliminated. However, the biaxially stretched nylon film has a large dimensional change during moisture absorption, and has a problem that it curls due to moisture absorption during the processing process and the shape is deformed due to shrinkage when a harsh treatment such as retort sterilization is applied. 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 has excellent heat resistance and dimensional stability, and can be used even when harsh treatment such as retort sterilization is applied. However, since PET film is brittle, a bag made of a laminated film using this is used. There was a problem that the bag was torn or punctured when it was 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 for a transparent gas barrier film. As a result, a technique has been proposed in which a packaging material for boil treatment or retort treatment, which is inexpensive and has excellent low elution and transparency, can be obtained (for example, Patent Document 3).
Since the conventional technique is easy to peel off at the interface between the polyester resin layer and the polyamide resin layer, there is a problem that the bag is easily broken when the bag is dropped and the contents are easily leaked.

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

Japanese Unexamined Patent Publication No. 6-278240 Japanese Unexamined Patent Publication No. 11-10725 Japanese Unexamined Patent Publication No. 2013-154605 Japanese Unexamined Patent Publication No. 2012-214248

The present invention has been made against the background of the problems of the prior art. That is, it is a laminated laminate composed of a gas barrier laminated film having an inorganic thin film layer and a protective layer in this order on a base material layer and a sealant layer, and is excellent in bag breaking resistance and bending resistance. It is also an object of the present invention to provide a gas barrier laminated film and a laminated laminate having excellent gas barrier properties even when used for applications subject to severe moist heat treatment such as retort sterilization.

Inorganic on PBT film is a means to obtain excellent gas barrier properties even when used in applications where harsh wet heat treatment such as retort sterilization is performed while having excellent bag-breaking resistance and bending resistance. 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 base material layer, a step of forming an inorganic thin film layer while feeding out a film roll to be a film base material layer, and subsequently a step of forming a protective film are performed. It is preferable to provide it. In particular, in the step of forming the protective film, after the applied coating film is heat-treated at a high temperature of about several tens of degrees 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 characteristic that the film tends to stretch when tension is applied under high temperature. The present inventors obtained this as a result of stretching the film base material layer and cracking the previously formed inorganic thin film layer when tension is applied while the film base material layer is heated in the process of forming the protective film. It has been found that the gas barrier property of the gas barrier film is lowered.

Therefore, the present inventor has made a gas barrier film by laminating an inorganic thin film layer on a film base material layer containing PBT as a main component, and the heat shrinkage rate and temperature rise process of the PBT film used as the base material layer. By setting the dimensional change rate in the temperature lowering process within a specific range, it is less likely to be deformed by the tension applied in the protective film forming process and the heating temperature, damage to the inorganic thin film layer can be suppressed, and moreover, such as retort sterilization. We have obtained the finding that good gas barrier properties can be maintained even after harsh wet heat treatment, and have solved the above problems.

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

The present inventors have excellent gas barrier properties such as bag breakage resistance and bending resistance, and also have excellent gas barrier properties even when used in applications such as retort sterilization that are subjected to severe moist heat treatment. It has become possible to provide a laminated laminate composed of a sex laminated film and a sealant layer thereof.

Measurement example of maximum dimensional change rate in MD direction

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

The base material layer used in the present invention can contain a polyester resin other than PBT for the purpose of adjusting the film-forming property at the time of 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, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6, in which at least one dicarboxylic acid selected from the above group is copolymerized. -Examples include a 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 amount of the polyester resin other than PBT added is 40% by mass or less, preferably 30% by mass or less. If the amount of polyester resin other than PBT added exceeds 40% by mass, the mechanical properties of PBT are impaired, impact strength, pinhole resistance, or bag breakage resistance becomes insufficient, and transparency and gas barrier properties are also obtained. 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 puncture strength, impact strength, pinhole resistance, bag breakage resistance, etc. decrease. Then it may become. The upper limit of the intrinsic viscosity of the PBT resin is preferably 1.3 dl / g. If it exceeds the above, the stress at the time of stretching becomes too high, and the film forming property may deteriorate. When PBT having a high intrinsic viscosity is used, it is necessary to raise the extrusion temperature to a high temperature because the melt viscosity of the resin becomes high. However, when the PBT resin is extruded at a higher temperature, decomposition products may be easily generated.

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

As the type 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 that haze is reduced. These can be expressed as transparent and slippery.

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

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

Next, a method for producing a film of a base material layer used in the present invention will be specifically described. It is not limited to these.
[Unstretched sheet molding process in base material layer production]
First, the film raw material is vacuum dried or hot air dried. Next, the raw materials are weighed, mixed, supplied to an extruder, heated and melted, and melt-casted in the form of 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 is a method in which a voltage is applied to an electrode installed in the vicinity of a molten resin sheet in contact with a rotating metal roll and in the vicinity of a surface opposite to the surface of the resin sheet in contact with the rotating metal roll. This is a method in which the resin sheet is charged and the resin sheet and the rotary 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 even more preferably 260 ° C. If it is less than the above, the discharge may become unstable. The upper limit of the resin melting temperature is preferably 280 ° C, more preferably 270 ° C. If it exceeds the above, the resin is decomposed and the film becomes brittle.

When the molten polyester resin is cast on an extruded cooling roll, it is preferable to reduce the difference in crystallinity in the width direction of the unstretched sheet. Specific methods for this include casting the molten raw material resin in multiple layers when extruding and casting the molten polyester resin, and lowering the cooling roll 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 equipment simplicity and maintainability. The number of layers of the molten raw material resin is preferably 60 or more. More preferably, it is 500. If the number of layers is too small, the distance between the 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 is preferably 100,000, more preferably 10,000, and even more preferably 7,000. Even if the number of theoretical stacks is made extremely large, the effect may be saturated.

When multi-layering is performed by 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) without a drive unit, and the fluid entering the mixer is sequentially stirred and mixed by an element. However, when the high-viscosity fluid is passed through the static mixer, the high-viscosity fluid is divided and laminated, and the laminated fluid is formed. Each time it passes through one element of the static mixer, the high viscosity fluid is split into two and then merged and stacked. Therefore, when a high-viscosity fluid is passed through a static mixer having n elements, a laminated fluid having a theoretical stacking number N = (2 to the nth power) is formed.

The upper limit of the cooling roll temperature when casting the molten polyester resin onto the extruded cooling roll is preferably 40 ° C. If it exceeds the above, the crystallinity may become too high and stretching may become difficult. The upper limit of the cooling roll temperature is preferably 25 ° C. When the temperature of the cooling roll is 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 base material layer production]
Next, the stretching method will be described. The stretching method can be either simultaneous biaxial stretching or sequential biaxial stretching, but in order to increase the puncture strength, it is necessary to increase the degree of surface orientation, and the film forming speed is high and the productivity is high. In the above, sequential biaxial stretching is most preferable.

The lower limit of the stretching temperature in the longitudinal stretching direction is preferably 55 ° C., more preferably 60 ° C. Breakage is unlikely to occur at 55 ° C. or higher. Further, since the vertical orientation of the film does not become too strong, the shrinkage stress during the heat fixing treatment can be suppressed, and a film with less distortion of the 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 is not too weak and the mechanical properties of the film are not deteriorated.

The lower limit of the draw 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 degree of surface orientation is increased, the piercing strength of the film is improved, and the thickness accuracy of the film is improved. The upper limit of the draw 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 of the film in the lateral direction does not become too strong, the shrinkage stress during the heat fixing process does not become too large, and the distortion of the molecular orientation in the lateral direction of the film becomes small, resulting in As a result, the vertical tearability is improved. Moreover, the effect of improving the mechanical strength and the 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 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, by relaxing in the MD direction, the Boeing phenomenon that occurs in the tenter can be reduced. Further, since the oriented and crystallized components of the film remain oriented, it is possible to reduce the dimensional change of the film 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 is determined by the raw materials used and the longitudinal stretching conditions, and relaxation cannot be performed beyond this. The upper limit of the relaxation rate in the MD direction is about 20%.

Relaxation in the MD direction can be performed by heating the film after longitudinal stretching at a temperature of 65 ° C. to 100 ° C. or lower and adjusting the speed difference of the rolls. As the heating means, any of roll, near infrared ray, far infrared ray, hot air heater and the like can be used. Further, the relaxation in the MD direction can be performed not immediately after the longitudinal stretching, but also in the lateral stretching (including the preheating zone) or the final heat treatment, for example, 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 Boeing 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 higher, fracture may be less likely 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 lower, the degree of orientation in the transverse direction increases, so that the mechanical properties are improved.

The lower limit of the draw 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 is not too weak, and the mechanical properties and thickness unevenness are improved. The upper limit of the draw 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 made 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 fixing process in base material layer production]
The lower limit of the heat fixing temperature in the heat fixing step is preferably 195 ° C., more preferably 200 ° C. When the temperature is 195 ° C. or higher, the heat shrinkage rate of the film is reduced, and the inorganic thin film layer is not easily damaged even after the retort treatment, so that the gas barrier property is improved. The upper limit of the heat fixing temperature is preferably 220 ° C., and if it is 220 ° C. or lower, the base film layer does not melt and is less likely to become brittle.

[Heat relaxation part process in base material layer production]
The lower limit of the relaxation rate in the heat relaxation section step is preferably 0.5%. If it is 0.5% or more, breakage may be less likely to occur during heat fixing. The upper limit of the relaxation rate is preferably 10%. When it is 10% or less, the shrinkage in the vertical direction at the time of heat fixing becomes small, and as a result, the distortion of the molecular orientation at the edge of the film becomes small, and the straight tearability is improved. In addition, the film is less likely to sag and uneven thickness is less likely to occur.

[Cooling process in base material layer production]
In the cooling step after relaxing in the heat relaxation section step, the temperature of the surface of the edge portion of the polyester film is preferably 80 ° C. or lower. If the temperature of the edge of the film after passing through the cooling process exceeds 80 ° C., the edge is stretched by the tension applied when winding the film, and as a result, the heat shrinkage rate of the edge in the vertical direction becomes high. As a result, the heat shrinkage distribution in the width direction of the roll becomes non-uniform, and when such a roll is heated and conveyed for vapor deposition processing, streaky wrinkles occur, and the final gas barrier is obtained. The physical properties of the film may become non-uniform in the width direction.

In the cooling step, as a method of setting the surface temperature of the film edge to 80 ° C. or lower, in addition to adjusting the temperature and air volume in the cooling step, a shielding plate is provided on the central side in the width direction of the cooling zone to select the edge. A method of cooling the film or a method of locally blowing cold air on the edge of the film can be used.

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

The upper limit of the degree of orientation (ΔNx) of the substrate layer film in the MD direction in the present invention is preferably 0.09, more preferably 0.085, and even more preferably 0.08. Within the above range, the mechanical properties and straight-line tearability of the base film are more preferable. The degree of orientation (ΔNx) in the MD direction is determined 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 ΔNx = Nx− (Ny + Nz) / 2. Calculated by the formula.

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

Further, the base material 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 known anchors. It may be coated, printed, decorated or the like.

Further, a layer of another material may be laminated on the base film of the present invention, and as a method thereof, the base film can be bonded after production or during film formation.

[Easy-adhesive layer and its formation method]
In the gas barrier laminated film of the present invention, an easy-adhesion layer can be provided between the base material layer film and the inorganic thin film layer for the purpose of ensuring the gas barrier property and the lamination strength after the retort treatment. The easy-adhesion layer provided between the base material layer film and the inorganic thin film layer includes urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, and polybutadiene-based resins, as well as epoxy-based, isocyanate-based, and polybutadiene-based resins. Examples include those to which a curing agent such as melamine 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. Such as polyhydric alcohol derivatives and the like. The resin composition used for these adhesion layers preferably contains a silane coupling agent having at least one type of 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. By adding the silane coupling agent, the lamination strength after the retort treatment is further improved.

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-deficient portion of the inorganic oxide generated during the formation of the inorganic thin film layer and the metal hydroxide, and exhibits 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 hydrolysis of the base material layer film and the easy-adhesion layer to form a crosslink.

As a method for forming the easy-adhesion layer, a conventionally known method such as a coating method can be adopted. Among the coating methods, the offline coating method and the inline coating method can be mentioned as preferable 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 at the time of coating depend on the coating thickness and the conditions of the apparatus, but immediately after coating, they are fed into the 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, the temperature is usually preferably about 50 to 250 ° C.

[Inorganic thin film layer and its formation method]
The inorganic thin film layer and the method for forming the inorganic thin film layer in the gas barrier laminated film of the present invention will be described. The inorganic thin film layer is a thin film made of a metal or an inorganic oxide. The material for 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 oxidation such as silicon oxide (silica), aluminum oxide (alumina), and a mixture of silicon oxide and aluminum oxide Things are preferred. 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 the metal content. If the Al concentration is less than 20% by mass, the water vapor barrier property may be lowered. 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 lowered. 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 film thickness of the inorganic thin film layer is usually 1 to 100 nm, preferably 5 to 50 nm. If 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 thickness exceeds 100 nm, the corresponding improvement effect of the gas barrier property can be obtained. This is not possible, and 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 known, for example, a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, or an ion plating method, or a chemical vapor deposition method (CVD method). The method may be adopted as appropriate. Hereinafter, a typical method for forming the inorganic thin film layer will be described by taking a silicon oxide / aluminum oxide thin film as an example. For example, when employing the vacuum evaporation method, a mixture of SiO2 and _A1 2 _{O 3} as evaporation raw material, or SiO2 and a mixture of Al is preferably used. Particles are usually used as these vapor deposition raw materials, but at that time, it is desirable that the size of each particle is such that the pressure at the time of vapor deposition does not change, and the particle size is preferably 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. Further, it is also possible to introduce oxygen, nitrogen, hydrogen, argon, carbon dioxide gas, water vapor or the like as the reaction gas, or to adopt reactive vapor deposition using means such as ozone addition and ion assist. Further, the film forming conditions can be arbitrarily changed, such as applying a bias to the film to be vapor-deposited (laminated film to be subjected to vapor deposition) or heating or cooling the film to be vapor-deposited. Such vapor deposition material, reaction gas, bias of the vapor deposition body, 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 laminated film before forming the protective film in which the inorganic thin film layer is laminated on the base material layer are as follows, using a thermal mechanical analyzer, an initial load of 0.2 g and a temperature rise rate of 10 ° C./min at 25 ° C. Dimensional change curve obtained by raising the temperature from 1 to 160 ° C and then lowering the temperature to 50 ° C at a temperature lowering rate of -10 ° C / min. The maximum dimensional change rate (Amax-Amin) in the MD direction is preferably 0.5 to 3% or less when the minimum value Amin (%) of the dimensional change rate with respect to the original film length is set.
In the above measurement, a large dimensional change rate in the temperature raising process indicates that it is easily stretched when heated, and a large dimensional change rate in the temperature lowering process shrinks in the process of cooling after heating. , Indicates that the dimensions change. Therefore, the fact that the maximum dimensional change rate represented by the above is large indicates that the dimensional increase / decrease when the protective film forming step or the food is heated / cooled by the retort treatment or the like becomes large.

The upper limit of the maximum dimensional change rate represented by the 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 layer may be damaged and the gas barrier property may be deteriorated after the food using the laminated laminate as a packaging bag is retort sterilized.

[Protective layer and its formation method]
The protective layer and the method for forming the protective layer in the gas barrier laminated film of the present invention will be described.
The gas barrier laminated film of the present invention has a protective layer on the inorganic thin film layer. For example, when the inorganic thin film layer is a metal oxide layer, the film is not a completely dense film, and minute defects are scattered. By applying a specific protective layer resin composition described later on the metal oxide layer to form the protective layer, the resin in the protective layer resin composition permeates 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 for the protective layer itself, the gas barrier performance of the gas barrier laminated film can be greatly improved.

The protective layer includes resins such as urethane-based resin, polyester-based resin, acrylic-based resin, titaniumate-based resin, isocyanate-based resin, imine-based resin, and polybutadiene-based resin, and epoxy-based curing agent, isocyanate-based curing agent, and melamine. Examples thereof 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 a polyhydric alcohol derivative solvent such as monomethyl ether.
Further, as the protective layer, a layer in which the protective layer is composed of at least a water-soluble polymer, a metal alkoxide, and a hydrolyzate thereof is also preferable.

In urethane resin, the polar group of the urethane bond interacts with the inorganic thin film layer and also has flexibility due to the presence of amorphous parts, so damage to the inorganic thin film layer can be suppressed even when a bending load is applied. It is preferable because it can be done.
The acid value of the urethane resin is preferably in the range of 10 to 60 mgKOH / g. It is more preferably in the range of 15 to 55 mgKOH / g, and even more preferably in 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, so that the appearance of the coat is good. It 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, the swelling of the protective layer due to molecular motion in the wet heat treatment process (heating-retaining-lowering) can be reduced.

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

In the present invention, the ratio of the aromatic diisocyanate or the aromatic aliphatic 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 the aromatic diisocyanate or the aromatic aliphatic diisocyanate is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, still more preferably 80 to 100 mol%. As such a resin, the "Takelac (registered trademark) WPB" series commercially available from Mitsui Chemicals, Inc. can be preferably used. If the ratio of the total amount of the aromatic diisocyanate or the aromatic aliphatic 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 or dimethylolbutanoic acid may be introduced as a copolymerization component as a polyol component. Further, if the carboxylic acid group-containing urethane resin is synthesized and then neutralized with a salt-forming agent, an aqueous dispersion urethane resin can be obtained. Specific examples of the salt forming agent include trialkylamines such as ammonia, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine and tri-n-butylamine, and N such as N-methylmorpholine and N-ethylmorpholine. Examples thereof include N-dialkylalkanolamines such as -alkylmorpholins, N-dimethylethanolamine and N-diethylethanolamine. These may be used alone or in combination of two or more.

As described above, a layer in which the protective layer is composed of at least a water-soluble polymer, a metal alkoxide, and a hydrolyzate thereof is also preferable.
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 an alcohol containing a water-soluble polymer having a hydroxyl group and one or more kinds of 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 in which an inorganic thin film layer is laminated on a base film with a coating agent using the mixed solution of the above as a solvent to form a thin film and heat-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. In some 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, a dipping method, a roll coating method, a gravure coating method, a reverse coating method, an air knife coating method, a comma coating method, a die coating method, a screen printing method, a spray coating method, a gravure offset printing, etc. shall be adopted. Can be done.

[Gas barrier laminated film (base material layer / inorganic thin film layer / protective layer)]
The upper limit of the heat shrinkage rate after heating the gas barrier laminated film of the present invention at 150 ° C. for 15 minutes in the MD direction (longitudinal stretching direction) is preferably 4.0%, more preferably 3.0%, and further. 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 material layer film that occurs in the process of forming the protective film or in the 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 gas barrier laminated film in the MD direction at 150 ° C. for 15 minutes in the present invention is preferably 1%. If it is less than the above, it tends to be stretched 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 lowered. In addition, it may become mechanically brittle.

The upper limit of the heat shrinkage rate after heating the gas barrier laminated film of the present invention in the TD direction (transverse stretching direction) at 150 ° C. for 15 minutes 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 material layer film that occurs in the process of forming the protective film or in the 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 gas barrier laminated film of the present invention at 150 ° C. for 15 minutes in the TD direction is preferably −1.0%. Even if it is less than the above, the effect of improvement cannot be obtained any more. In addition, it may become mechanically brittle.

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

The upper limit of the maximum dimensional change rate represented by the 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 layer may be damaged and the gas barrier property may be deteriorated after the food using the laminated laminate as a packaging bag is retort sterilized.

The lower limit of the piercing strength of the gas barrier laminated film of the present invention is 0.6 N / μm. If it is 0.6 N / μm or more, the strength becomes sufficient when used as a bag. The upper limit of the piercing strength of the gas barrier laminated film of the present invention is not particularly limited, but is preferably 1.5 N / μm, more preferably 1.0 N / μm, and even more preferably 0.74 N / μm. The upper limit of piercing strength is to balance with other properties such as the strength of the film's waist.

[Laminate laminate and its formation method]
When the laminated film of the present invention is used as a packaging material, it is preferable to form a heat-sealing resin layer called a sealant. The heat-sealing resin layer is usually provided on the upper side of the inorganic thin film layer, but may be provided on the outside of the base material layer film (the surface opposite to the inorganic thin film layer side). The heat-sealing 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 as long as it can sufficiently exhibit sealant adhesiveness, and is a polyethylene resin such as HDPE, LDPE, LLDPE, a polypropylene resin, or an ethylene-vinyl acetate copolymer. , Ethylene-α-olefin random copolymer, ionomer resin and the like can be used.

Further, in the laminated laminate of the present invention, at least one or more printing layers or other plastic base materials and / or paper base materials may be laminated on the outer side and / or between layers thereof. As the printing ink forming the printing layer, water-based and solvent-based resin-containing printing inks can be preferably used. Examples of the resin used for the printing ink include an acrylic resin, a urethane resin, a polyester resin, a vinyl chloride resin, a vinyl acetate copolymer resin, and a mixture thereof. Known printing inks include antistatic agents, light blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, antifoaming agents, cross-linking agents, blocking agents, antioxidants and the like. Additives may be included. The printing method for providing the print 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 drying can be used.

Based on the above, the laminated laminate of the present invention is excellent in bag breaking resistance and bending resistance, and can be used for packaging hard contents such as dry matter packaging before and after bag making, and after bag making, and retort. It has excellent gas barrier properties even when used in applications that are subjected to severe moist heat treatment such as sterilization.

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples. The film was evaluated by the following measurement method.

[Thickness of base film]
It was measured using a dial gauge in accordance with JIS K7130-199 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 rate in the MD direction of the gas barrier laminated film before and after the formation of the protective layer]
The gas barrier laminated film before the protective layer was formed and the gas barrier laminated film after the protective layer was formed were heated from room temperature to 160 ° C using a thermal mechanical analyzer (TMA) manufactured by Shimadzu Corporation, and then 160 ° C to 50 ° C. The temperature was lowered to a degree, and the dimensional change of the laminated film was measured. However, the rate of temperature rise and fall 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 film original length in the temperature raising process and the minimum value Amin (%) of the dimensional change rate with respect to the film original length in the temperature lowering process are read, and MD The maximum dimensional change rate (Amax-Amin) in the direction was calculated.

[Preparation of laminated laminate]
Urethane-based two-component curable adhesive (“Takelac (registered trademark) A525S” manufactured by Mitsui Kagaku Co., Ltd. and “Takenate” are placed on the protective layer side of the gas barrier laminated films shown in Examples 1 to 7 and Comparative Examples 1 to 4, which will be described later. Unstretched polypropylene film with a thickness of 70 μm as a heat-sealable resin layer (“P1147” manufactured by Toyo Boseki Co., Ltd.) by a dry laminating method using (registered trademark) A50 at a ratio of 13.5: 1 (mass ratio). ”) Are laminated 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 laminated laminate]
The above-mentioned laminated laminate is cut into a size of 20.3 cm (8 inches) × 27.9 cm (11 inches), and the cut rectangular test film is subjected to a temperature of 23 ° C. and a relative humidity of 50%. It was left for 24 hours or more for conditioning. After that, 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 is fixed to the outer circumference of the disk-shaped fixing head of a gelboflex tester (manufactured by Rigaku Kogyo Co., Ltd., NO.901 type) (based on the MIL-B-131C standard), and the cylindrical film is fixed. The other end of the tester was fixed to the outer circumference of the disk-shaped movable head of the tester facing the fixed head at a distance of 17.8 cm (7 inches). Then, the movable head is rotated 440 ° in the direction of the fixed head while approaching 7.6 cm (3.5 inches) along the axes of both heads facing each other in parallel, and subsequently 6.4 cm (6.4 cm) without rotation. After going straight (2.5 inches), a one-cycle bending test in which those movements are executed in the opposite directions to return the movable head to the initial position is performed continuously at a speed of 40 cycles per minute for 2000 cycles. Repeated. The implementation was carried out at 5 ° C. After that, the number of pinholes generated in the portion within 17.8 cm (7 inches) × 27.9 cm (11 inches) excluding the fixed head of the tested film and the portion fixed to the outer circumference of the movable head was measured (that is,). The number of pinholes per 497 cm ² (77 square inches) was measured).

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

[Oxygen permeability (OTR) of laminated laminate]
The temperature of the above-mentioned laminated laminate is 23, using an oxygen permeability measuring device (“OX-TRAN 2/20” manufactured by MOCON) according to the electrolytic sensor method (Appendix A) of JIS-K7126-2. The oxygen permeability under normal conditions was measured in an atmosphere of ° C. and a relative humidity of 65%. The oxygen permeability was measured in the direction in which oxygen permeates from the base film side to the sealant side.

[Oxygen permeability (OTR) after retort of laminated laminate]
The above-mentioned laminated laminate was subjected to a wet heat treatment by holding it 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 wet heat treatment was described above. Oxygen permeability was measured in the same manner.

[Moisture vapor transmission rate (WVTR) of laminated laminate]
A water vapor transmission rate measuring device (“PERMATRAN-W1A” manufactured by MOCON) was used for the above-mentioned laminated laminate according to the JIS-K7129-1992 B method, and the temperature was 40 ° C. and the relative humidity was 90 RH%. , The water vapor transmission rate under normal conditions was measured. The water vapor transmission rate was measured in the direction in which water vapor permeated from the base film side to the sealant side.

[Moisture vapor transmission rate (WVTR) after retort of laminated laminate]
The above-mentioned laminated laminate was subjected to a wet heat treatment by holding it 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 wet heat treatment was described above. The water vapor transmission rate was measured in the same manner.

The details of the raw material resin and the coating liquid used in this example and the comparative example are described below.
1) PBT resin: 1100-211XG (CHANGE CHUN PLASTICS CO., LTD., Intrinsic viscosity 1.28 dl / g) was used as the PBT resin used in the production of the base material layer films A1 to A11 described later.
2) PET resin: The PET resin used in the production of the base material layer films A1 to A11 described later was a PET resin manufactured by Toyobo Co., Ltd. and having an intrinsic viscosity of 0.62 dl / g.

3) Resin having an oxazoline group for an easy-adhesion layer (A): As a resin having an oxazoline group, a commercially available water-soluble oxazoline group-containing acrylate (“Epocross (registered trademark) WS-300” manufactured by Nippon Catalyst 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 easy-adhesion layer: As an acrylic resin, a 25% by mass emulsion of a commercially available acrylic acid ester copolymer (“Mobile (registered trademark) 7980” manufactured by Nichigo Vinyl Co., Ltd.) was prepared. The acid value (theoretical value) of this acrylic resin (B) was 4 mgKOH / g.

5) Urethane resin (C) for easy-adhesion layer: As a urethane resin, a dispersion of a commercially available polyester urethane resin (“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 aromatic aliphatic diisocyanate to the entire polyisocyanate component measured by 1H-NMR was 55 mol%.

6) Urethane resin (D) for the protective layer ;: As the urethane resin, a dispersion of a commercially available 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 aromatic aliphatic diisocyanate to the entire polyisocyanate component measured by 1H-NMR was 85 mol%.

7) Coating liquid used for the easy-adhesion layer 1
Each material was mixed at the following blending ratio to prepare a coating liquid (resin composition for easy adhesive layer).
Water 54.40% by mass
Isopropanol 25.00% by mass
Oxazoline group-containing resin (A) 15.00% by mass
Acrylic resin (B) 3.60% by mass
Urethane resin (C) 2.00% by mass

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

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

The method for producing the base material layer film used in each Example and Comparative Example is described below.
<Preparation of Base Material Layer Film; Examples 1-1, 1-2>
Using a uniaxial extruder, 80% by mass of polybutylene terephthalate resin and 20% by mass of polyethylene terephthalate resin are mixed, and silica particles with an average particle size of 2.4 μm as inert particles are used as silica concentrations with respect to the mixed resin. After melting the mixture so as to be 900 ppm at 290 ° C., the melt line was introduced into a 12-element static mixer. As a result, the polybutylene terephthalate melt was divided and laminated to obtain a multilayer melt made of the same raw material. It was cast from a T-die at 265 ° C. and adhered to a cooling roll at 15 ° C. by an electrostatic adhesion method to obtain an unstretched sheet.
Then, the roll was 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 a 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 vertically 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 the tension heat treatment and the relaxation treatment in the TD direction of 9% for 1 second, the grips 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 the film forming conditions, physical properties and evaluation results of the obtained film.
In the film forming step of the biaxially stretched film of the base material layer film, the resin composition for the easy-adhesion layer (coating liquid 1) was applied by the fountain bar coating method after stretching in the MD direction. Then, the solvent was led to a tenter while drying, and the solvent was volatilized and dried at a preheating temperature of 70 ° C. Next, the film was stretched, heat-treated and relaxed in the TD direction under the film-forming conditions shown in Tables 1 and 2 to obtain a laminated film A1 in which an easy-adhesion layer was formed on one side of a PBT film having a thickness of 15 μm.

<Preparation of Base Material Layer Film; Examples 1-2-1-7, Comparative Examples 1-1-1-4 and Examples 2-2-2-7, Comparative Examples 2-1-2-4>
The substrate layer films A2 to A11 were produced in the same manner as the substrate layer film 1 except that the MD stretch ratio, the MD relaxation rate, and the relaxation rate in the TD direction were changed to the conditions shown in Tables 1 and 2.

The method of forming the inorganic thin film layer in each Example and Comparative Example is described below.
<Formation of aluminum oxide _(A1 2 _{O 3)} inorganic thin layer>
As the inorganic thin film layer M1, aluminum oxide was vapor-deposited on the base material layer films A1 to A5 of Examples and the base material layer films A8 to 11 of Comparative Examples. In the method of depositing aluminum oxide on a base film, the film is set on the unwinding side of a continuous vacuum deposition machine and run through a cooling metal drum to wind the film. At this time, the continuous vacuum vapor deposition machine is ^{depressurized to 10 -4} Torr or less, metallic aluminum having a purity of 99.99% is loaded into an alumina crucible from the lower part of the cooling drum, and the metallic aluminum is heated and evaporated into the vapor. An aluminum oxide film having a thickness of 30 nm was formed by adhering and depositing on a film while supplying oxygen and causing an oxidation reaction.

<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 films A6 and A7 of the examples by an electron beam deposition method. _{Particulate SiO 2} (purity 99.9%) and A1 ₂ O ₃ (purity 99.9%) having a thickness of about 3 mm to 5 mm were used as the vapor deposition source. The thickness of the thus obtained films (inorganic thin layer / adhesive layer containing film) inorganic thin layer in the _(SiO 2 / _A1 2 _{O 3} composite oxide layer) 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 laminated film having an easy-adhesion layer / an inorganic thin film layer / a protective layer was produced on the base film.

<Formation of protective layer 2>
A coating material 1, a coating material 2, and a coating material 3 are mixed on the inorganic thin film layers formed on the base material layer films A1 to A11 so that the blending ratio (mass%) is 70/20/10. The working 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 laminated film having an easy-adhesion layer / an inorganic thin film layer / a protective layer was produced on the base film.

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

As shown in Tables 1 and 2, the gas barrier laminated film obtained by the present invention has a maximum dimensional change as seen in Examples 1-1 to 1-7 and Examples 2-1 to 2-7. By setting the ratio within a predetermined range, good gas barrier properties can be exhibited without damaging the inorganic thin film layer due to the formation of the protective film, and there is little dimensional change in the heating-cooling process even after the retort treatment. Therefore, it can be confirmed that the damage received by the gas barrier layer is reduced and good gas barrier properties can be maintained. Furthermore, since it is excellent in bag breakage 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 because the maximum dimensional change rate and the heat 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 lateral 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 under normal conditions. The gas barrier property was poor.
In Comparative Examples 1-4 and 2-4, since the ratio of PBT was small, even if the gas barrier property was good, the piercing strength and the bag breaking resistance were poor.

According to the present invention, the gas barrier is excellent in gas barrier property, dimensional stability, workability, bending resistance, and bag breaking resistance, and is also excellent in applications such as retort sterilization that are subjected to severe moist heat treatment. A gas-barrier laminated film having properties and a laminated laminated body using the same can be obtained.
INDUSTRIAL APPLICABILITY The present invention provides a gas-barrier laminated film having excellent gas barrier properties, as well as bag-breaking resistance and bending resistance, and a laminated laminate using the same, not only in a normal state but also after performing a wet heat treatment. We were able to. Such a gas barrier laminated film has the advantages of being easy to manufacture, excellent in economy and production stability, and easy to obtain homogeneous characteristics. Therefore, such a gas barrier laminated film is widely applied as a food packaging material. Since it can be done, it is expected to greatly contribute 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 elements, and semiconductor elements.

Claims (13)

A laminated film composed of at least a base material layer / an inorganic thin film layer / a protective layer, which satisfies the following conditions (a) to (d).
(A) The base material layer comprises a resin composition containing 60% by mass or more of polybutylene terephthalate resin.
(B) The piercing strength is 0.6 N / μm or more.
(C) The heat shrinkage rate in the MD direction is 1 to 4% and the heat shrinkage rate in the TD direction is -1 to 3% at a test temperature of 150 ° C. and a heating time of 15 minutes.
(D) Obtained by raising the temperature from 25 ° C to 160 ° C at an initial load of 0.2 g and a heating rate of 10 ° C./min using a thermal mechanical analyzer, and then lowering the temperature to 50 ° C. at a temperature lowering rate of -10 ° C./min. In the dimensional change curve in the MD direction, the maximum value of the dimensional change rate with respect to the film original length in the temperature raising process is Amax (%), and the minimum value of the dimensional change rate with respect to the film original length in the temperature lowering process is Amin (%). The dimensional change rate (Amax-Amin) is 2% or less. The gas barrier laminated film according to claim 1, wherein an easy-adhesion layer is provided between the base material layer and the inorganic thin film layer. The gas barrier laminated film according to claim 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. The gas barrier laminated film according to claim 2 or 3, wherein the easy-adhesion layer comprises a resin composition containing a resin having an oxazoline group. The gas barrier laminated film according to any one of claims 1 to 4 , wherein the protective layer is a urethane resin containing an aromatic or aromatic aliphatic component. The gas barrier laminated film according to any one of claims 1 to 5, wherein the protective layer is composed of at least a water-soluble polymer, a metal alkoxide, and a hydrolyzate thereof. Consists satisfy substrate layer / inorganic thin film layer having the following (e), and forming a protective layer on the gas barrier laminate film according to any one of claims 1 to 6, the gas barrier layered Film manufacturing method.
(E) The gas barrier laminated film before forming the protective film is heated from 25 ° C. to 160 ° C. at an initial load of 0.2 g at a heating rate of 10 ° C./min using a thermal mechanical analyzer, and then lowered at a temperature decrease rate of −10 ° C./. Dimensional change curve obtained by lowering the temperature to 50 ° C in minutes Amax (%), the maximum value of the dimensional change rate with respect to the original film length in the temperature raising process, and Amin (%), the minimum value of the dimensional change rate with respect to the original film length in the temperature lowering process. The maximum dimensional change rate (Amax-Amin) in the MD direction is 0.5 to 3% or less. Oxygen permeability after retort treatment at 120 ° C. for 30 minutes, which comprises at least the gas barrier laminated film according to any one of claims 1 to 6 ^{, is 15 ml / m 2} , day, MPa or less, and steam permeability is 2 g. Laminated laminate with / m ² · day or less. The laminated laminate according to claim 8 , wherein a biaxially stretched polyethylene terephthalate film is laminated on the surface of the gas barrier laminated film on the substrate layer side. A packaging bag made of the laminated laminate according to claim 8 or 9. The packaging bag according to claim 10 , wherein the packaging bag is used for retort. The packaging bag according to claim 10, wherein the packaging bag is used for heating in a microwave oven.
The packaging bag according to claim 10 , wherein the packaging bag is used for vacuum packaging.

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